ASCL1 (Achaete-scute homolog 1, also known as MASH1/hASH1) is a proneural basic helix-loop-helix (bHLH) transcription factor that functions as both a classical transcriptional activator and a pioneer factor capable of accessing closed chromatin. It binds E-box motifs (CANNTG, particularly CACCTG) as a heterodimer with E-proteins (TCF3/E12/E47, TCF4) to activate neuronal and neuroendocrine gene programs. ASCL1 plays essential roles in neuronal differentiation, neuronal fate commitment, and neuroendocrine cell development. It is a master regulator of the SCLC-A (neuroendocrine) subtype of small cell lung cancer and directly activates targets including INSM1, MYT1, DLL1, and DLL3 (Notch pathway modulators). ASCL1 protein stability is regulated by CDK2-CyclinA2 phosphorylation, HUWE1-mediated ubiquitination, and protection via E-protein heterodimerization.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0030182
neuron differentiation
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: Neuron differentiation is a core function of ASCL1. The IBA annotation is well-supported by phylogenetic analysis and extensive experimental evidence. ASCL1 (MASH1) is essential for proper development of olfactory and autonomic neurons and for neuronal differentiation in the CNS and PNS (PMID:10903890). ASCL1 overexpression increases neurogenesis in human neural progenitor cells (PMID:19008346).
Reason: This is a core function of ASCL1. The protein is classified as a proneural bHLH transcription factor whose primary role is driving neuronal differentiation. Multiple experimental studies confirm this function, and the IBA phylogenetic inference is consistent with the extensive literature.
Supporting Evidence:
PMID:10903890
The basic helix-loop-helix (bHLH) transcription factor mammalian achaete-scute homolog-1 (MASH-1 in mouse and HASH-1 in human) is essential for proper development of olfactory and most peripheral autonomic neurons, and for the formation of distinct neuronal circuits within the central nervous system.
PMID:19008346
By overexpressing one of these, the transcription factor ASCL1, we were able to regain neurogenesis from hNPC(VM) cultures
file:human/ASCL1/ASCL1-deep-research-cyberian.md
model: deep-research
|
|
GO:0007423
sensory organ development
|
IBA
GO_REF:0000033 |
KEEP AS NON CORE |
Summary: ASCL1 is essential for development of olfactory neurons, which are part of the olfactory sensory organ system. The IBA annotation captures the role in sensory (specifically olfactory) development.
Reason: While ASCL1 is essential for olfactory neuron development (a sensory system), this is a more peripheral consequence of its neuronal differentiation function rather than a core molecular function. The term is appropriate but represents a downstream developmental phenotype.
Supporting Evidence:
PMID:10903890
The basic helix-loop-helix (bHLH) transcription factor mammalian achaete-scute homolog-1 (MASH-1 in mouse and HASH-1 in human) is essential for proper development of olfactory and most peripheral autonomic neurons, and for the formation of distinct neuronal circuits within the central nervous system.
|
|
GO:0045944
positive regulation of transcription by RNA polymerase II
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: ASCL1 is a transcriptional activator that transactivates E-box containing reporter constructs (PMID:10903890). It drives transcription of neuronal and neuroendocrine gene programs.
Reason: This is a core function. ASCL1 functions as a transcriptional activator, directly demonstrated by reporter assays showing transactivation of E-box containing constructs when complexed with E-proteins like E2-2/TCF4.
Supporting Evidence:
PMID:10903890
The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro, and transactivates an E-box containing reporter construct in vivo.
|
|
GO:0000977
RNA polymerase II transcription regulatory region sequence-specific DNA binding
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: ASCL1 binds sequence-specifically to E-box elements (CANNTG, particularly CACCTG) in promoter and enhancer regions. This DNA binding is essential for its transcription factor activity.
Reason: This is a core molecular function. Multiple studies demonstrate E-box binding by gel shift assays and functional studies. ASCL1 binds as a heterodimer with E-proteins to specific DNA sequences.
Supporting Evidence:
PMID:10903890
The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro
PMID:11736660
Binding of hASH-1 to the E-box cluster was confirmed by gel mobility-shift assay.
|
|
GO:0000981
DNA-binding transcription factor activity, RNA polymerase II-specific
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: ASCL1 is a DNA-binding transcription factor that regulates RNA polymerase II-dependent transcription. This is the fundamental molecular function of ASCL1 as a bHLH transcription factor.
Reason: This is the core molecular function of ASCL1. It binds DNA via its bHLH domain as a heterodimer with E-proteins and regulates transcription of target genes. IDA evidence also supports this (PMID:10903890).
Supporting Evidence:
PMID:10903890
The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro, and transactivates an E-box containing reporter construct in vivo.
|
|
GO:0090575
RNA polymerase II transcription regulator complex
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: ASCL1 functions as part of a transcriptional regulatory complex, forming heterodimers with E-proteins (TCF3, TCF4) and interacting with chromatin remodeling complexes (mSWI/SNF via ARID1A, SMARCC1).
Reason: ASCL1 functions in transcription regulator complexes. It heterodimerizes with E-proteins for DNA binding and interacts with mSWI/SNF chromatin remodeling complexes (PMID:36931659). UniProt records interactions with TCF3, TCF4, ARID1A, and SMARCC1.
Supporting Evidence:
PMID:10903890
E2-2 forms a functional complex with HASH-1
PMID:36931659
ASCL1 interacts with BAF SWI/SNF chromatin remodeling complexes
|
|
GO:0050767
regulation of neurogenesis
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: ASCL1 is a master regulator of neurogenesis. Overexpression increases neurogenesis (PMID:19008346), and it is required for neuronal differentiation from progenitor cells.
Reason: This is a core biological process for ASCL1. The IBA annotation is well-supported by extensive experimental evidence showing ASCL1 positively regulates neurogenesis.
Supporting Evidence:
PMID:19008346
Regionally specified human neural progenitor cells derived from the mesencephalon and forebrain undergo increased neurogenesis following overexpression of ASCL1.
|
|
GO:0003677
DNA binding
|
IEA
GO_REF:0000043 |
MARK AS OVER ANNOTATED |
Summary: ASCL1 binds DNA via its bHLH domain. This IEA annotation based on UniProt keywords is correct but less specific than other available annotations (E-box binding, sequence-specific DNA binding).
Reason: While correct, this term is too general. More specific terms like E-box binding (GO:0070888) and sequence-specific double-stranded DNA binding (GO:1990837) are available and already annotated with experimental evidence.
Proposed replacements:
E-box binding
sequence-specific double-stranded DNA binding
|
|
GO:0003700
DNA-binding transcription factor activity
|
IEA
GO_REF:0000120 |
ACCEPT |
Summary: ASCL1 is a DNA-binding transcription factor. This IEA annotation is correct and supported by IDA evidence from PMID:10903890.
Reason: This is a core molecular function. The IEA annotation is correct and redundant with the IDA annotation from PMID:10903890, which provides experimental support.
Supporting Evidence:
PMID:10903890
The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro, and transactivates an E-box containing reporter construct in vivo.
|
|
GO:0005634
nucleus
|
IEA
GO_REF:0000120 |
ACCEPT |
Summary: ASCL1 localizes to the nucleus where it functions as a transcription factor. This is supported by multiple IDA annotations (PMID:12858003, PMID:17507989, PMID:18311112).
Reason: Nuclear localization is essential for ASCL1 function as a transcription factor. The IEA annotation is correct and supported by multiple IDA annotations from immunohistochemistry studies.
Supporting Evidence:
PMID:12858003
Immunohistochemically, pulmonary neuroendocrine cells (PNECs) are positive for Mash1
|
|
GO:0006357
regulation of transcription by RNA polymerase II
|
IEA
GO_REF:0000002 |
ACCEPT |
Summary: ASCL1 regulates transcription by RNA polymerase II, functioning as both an activator and repressor depending on context and target gene.
Reason: This is a core function of ASCL1. It regulates transcription both positively (neuronal genes) and negatively (e.g., PACE4 gene). The IEA annotation is appropriate.
Supporting Evidence:
PMID:10903890
transactivates an E-box containing reporter construct in vivo
PMID:11736660
The overexpression of hASH-1 or MASH-1 causes a marked decrease in endogenous PACE4 gene expression
|
|
GO:0007399
nervous system development
|
IEA
GO_REF:0000120 |
ACCEPT |
Summary: ASCL1 is essential for nervous system development, particularly neuronal differentiation in CNS and PNS.
Reason: This is a core biological process. ASCL1 is essential for CNS and PNS neuron development. More specific child terms are also annotated, but this broader term is appropriate as a summary.
Supporting Evidence:
PMID:10903890
essential for proper development of olfactory and most peripheral autonomic neurons, and for the formation of distinct neuronal circuits within the central nervous system
|
|
GO:0030154
cell differentiation
|
IEA
GO_REF:0000043 |
MARK AS OVER ANNOTATED |
Summary: ASCL1 drives cell differentiation, specifically neuronal and neuroendocrine differentiation.
Reason: While correct, this term is too general. More specific terms like neuron differentiation (GO:0030182) and neuroendocrine cell differentiation are more appropriate and already annotated.
Proposed replacements:
neuron differentiation
|
|
GO:0046983
protein dimerization activity
|
IEA
GO_REF:0000002 |
ACCEPT |
Summary: ASCL1 forms heterodimers with E-proteins (TCF3, TCF4) via its HLH domain. This dimerization is essential for DNA binding and transcriptional activity.
Reason: Dimerization is essential for ASCL1 function. It heterodimerizes with E-proteins to bind DNA. UniProt documents interactions with TCF3 and TCF4 with multiple experiments.
Supporting Evidence:
PMID:10903890
E2-2 interacts with HASH-1 in both yeast and mammalian cells. The HASH-1/E2-2 complex binds an E-box
|
|
GO:0070888
E-box binding
|
IEA
GO_REF:0000117 |
ACCEPT |
Summary: ASCL1 binds E-box motifs (CANNTG, specifically CACCTG). This is demonstrated by gel shift assays and is essential for its transcription factor activity.
Reason: E-box binding is a core molecular function of ASCL1. This IEA annotation is correct and supported by IDA annotations from PMID:10903890 and PMID:11736660.
Supporting Evidence:
PMID:10903890
The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro
PMID:11736660
Binding of hASH-1 to the E-box cluster was confirmed by gel mobility-shift assay
|
|
GO:0005515
protein binding
|
IPI
PMID:10903890 HASH-1 and E2-2 are expressed in human neuroblastoma cells a... |
REMOVE |
Summary: This annotation captures protein-protein interaction with E2-2/TCF4, identified by yeast two-hybrid. However, a more specific term (bHLH transcription factor binding) is available and annotated.
Reason: The generic "protein binding" term is uninformative. The specific interaction with E2-2 is better captured by GO:0043425 (bHLH transcription factor binding) which is also annotated from this reference.
Proposed replacements:
bHLH transcription factor binding
Supporting Evidence:
PMID:10903890
HASH-1 and E2-2 are expressed in human neuroblastoma cells and form a functional complex.
|
|
GO:0005515
protein binding
|
IPI
PMID:32296183 A reference map of the human binary protein interactome. |
REMOVE |
Summary: This annotation is from the HuRI high-throughput protein interactome study. While the interactions are likely valid, "protein binding" is uninformative without specifying the binding partner.
Reason: Generic "protein binding" annotations from high-throughput studies provide limited functional insight. The term is too broad to be useful for understanding ASCL1 function.
Supporting Evidence:
PMID:32296183
Apr 8. A reference map of the human binary protein interactome.
|
|
GO:0005515
protein binding
|
IPI
PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling... |
REMOVE |
Summary: This annotation is from the BioPlex proteome-scale network study. While interactions are documented, the generic term provides no specific functional information.
Reason: Generic "protein binding" from high-throughput AP-MS studies is uninformative. More specific interaction terms should be used where the functional relevance is understood.
Supporting Evidence:
PMID:33961781
2021 May 6. Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.
|
|
GO:0005515
protein binding
|
IPI
PMID:36931659 Pioneer factor ASCL1 cooperates with the mSWI/SNF complex at... |
MODIFY |
Summary: This study demonstrates ASCL1 interaction with mSWI/SNF chromatin remodeling complexes (ARID1A, SMARCC1). The specific functional context (chromatin remodeling cooperation) is known.
Reason: The interaction with mSWI/SNF components is functionally relevant (pioneer factor activity with chromatin remodelers). A more specific term capturing the chromatin remodeling complex interaction would be more informative.
Proposed replacements:
DNA-binding transcription factor binding
Supporting Evidence:
PMID:36931659
ASCL1 interacts with BAF SWI/SNF chromatin remodeling complexes, primarily at targets where it acts as a nonpioneer factor
|
|
GO:0003358
noradrenergic neuron development
|
IEA
GO_REF:0000107 |
ACCEPT |
Summary: ASCL1 is required for noradrenergic neuron development, as demonstrated by mutation studies in congenital central hypoventilation syndrome patients (PMID:14532329).
Reason: This is a core biological process. HASH-1 mutations impair noradrenergic neuronal development in an in vitro model system, demonstrating the requirement for ASCL1 in this process.
Supporting Evidence:
PMID:14532329
All HASH-1 mutant alleles impaired noradrenergic neuronal development, when overexpressed from adenoviral constructs.
|
|
GO:0003682
chromatin binding
|
IEA
GO_REF:0000107 |
ACCEPT |
Summary: ASCL1 exhibits pioneer factor activity, binding nucleosomal DNA and remodeling chromatin at neuronal enhancers. This is demonstrated by PMID:36931659.
Reason: Chromatin binding is a core function of ASCL1 as a pioneer transcription factor. It binds nucleosomal DNA and cooperates with mSWI/SNF to remodel chromatin.
Supporting Evidence:
PMID:36931659
Pioneer transcription factors are thought to play pivotal roles in developmental processes by binding nucleosomal DNA to activate gene expression
|
|
GO:0003690
double-stranded DNA binding
|
IEA
GO_REF:0000107 |
ACCEPT |
Summary: ASCL1 binds double-stranded DNA at E-box motifs. This is demonstrated by gel shift assays and functional studies.
Reason: This is a valid molecular function. ASCL1 binds dsDNA as a heterodimer with E-proteins. More specific IDA annotations exist (sequence-specific double-stranded DNA binding).
Supporting Evidence:
PMID:11736660
Binding of hASH-1 to the E-box cluster was confirmed by gel mobility-shift assay
|
|
GO:0007507
heart development
|
IEA
GO_REF:0000107 |
KEEP AS NON CORE |
Summary: This annotation is transferred from mouse/rat orthologs via Ensembl Compara. While ASCL1 may have some role in cardiac development (possibly via autonomic innervation), this is not a well-characterized primary function of human ASCL1.
Reason: Heart development is not a primary function of ASCL1. Any role is likely secondary to autonomic nervous system development. The annotation is not wrong but represents a peripheral/indirect function.
|
|
GO:0021879
forebrain neuron differentiation
|
IEA
GO_REF:0000107 |
ACCEPT |
Summary: ASCL1 is expressed in forebrain and drives neuron differentiation there, including GABAergic interneuron differentiation (PMID:12050665).
Reason: This is a specific manifestation of ASCL1's neuronal differentiation function in the forebrain. Supported by evidence showing ASCL1/Mash1 expression in cortical progenitors.
Supporting Evidence:
PMID:12050665
One lineage expresses Dlx1/2 and Mash1 transcription factors, represents 65% of neocortical GABAergic neurons in humans, and originates from Mash1-expressing progenitors of the neocortical ventricular and subventricular zone of the dorsal forebrain.
|
|
GO:0030182
neuron differentiation
|
IEA
GO_REF:0000107 |
ACCEPT |
Summary: Duplicate annotation of neuron differentiation via Ensembl Compara transfer. The IBA annotation already captures this function with phylogenetic support.
Reason: This is a core function. Duplicate with IBA annotation but both are valid. The multiple evidence codes reinforce the importance of this function.
Supporting Evidence:
PMID:10903890
essential for proper development of olfactory and most peripheral autonomic neurons
|
|
GO:0032526
response to retinoic acid
|
IEA
GO_REF:0000107 |
KEEP AS NON CORE |
Summary: ASCL1 expression is regulated in response to retinoic acid treatment. In SH-SY5Y neuroblastoma cells, ASCL1 expression is reduced after RA treatment as cells differentiate (PMID:12000752).
Reason: ASCL1 responds to retinoic acid (expression is downregulated during RA-induced differentiation), but this is a regulatory response rather than a core function. IEP evidence exists (PMID:12000752).
Supporting Evidence:
PMID:12000752
expression of neuroblast-specific ASCL1 (HASH-1) gene was promptly reduced after RA treatment
|
|
GO:0042802
identical protein binding
|
IEA
GO_REF:0000107 |
UNDECIDED |
Summary: ASCL1 may form homodimers, though heterodimerization with E-proteins is the functionally characterized interaction mode for DNA binding.
Reason: While ASCL1 may homodimerize, the functionally important interaction is heterodimerization with E-proteins. The evidence for homodimerization being functionally relevant is limited.
|
|
GO:0043025
neuronal cell body
|
IEA
GO_REF:0000107 |
KEEP AS NON CORE |
Summary: ASCL1 is expressed in neuronal cell bodies during development. As a transcription factor, it is primarily nuclear within these cells.
Reason: The cellular component annotation is technically correct but less informative than "nucleus." ASCL1 is found in neuronal progenitors and differentiating neurons, localized to the nucleus.
|
|
GO:0043565
sequence-specific DNA binding
|
IEA
GO_REF:0000107 |
ACCEPT |
Summary: ASCL1 binds DNA in a sequence-specific manner, recognizing E-box motifs. This is well-supported by experimental evidence.
Reason: Sequence-specific DNA binding is a core molecular function. IDA evidence exists for the more specific term (sequence-specific double-stranded DNA binding) from PMID:28473536.
Supporting Evidence:
PMID:10903890
The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro
|
|
GO:0045665
negative regulation of neuron differentiation
|
IEA
GO_REF:0000107 |
REMOVE |
Summary: This annotation appears contradictory since ASCL1 is primarily a positive regulator of neuron differentiation. The IDA annotation from PMID:12000752 appears to be an error in interpretation.
Reason: ASCL1 is primarily a positive regulator of neuronal differentiation. The cited evidence (PMID:12000752) shows ASCL1 is downregulated during differentiation, which is different from ASCL1 negatively regulating differentiation. This annotation appears to be an error.
|
|
GO:0045666
positive regulation of neuron differentiation
|
IEA
GO_REF:0000107 |
ACCEPT |
Summary: ASCL1 positively regulates neuron differentiation. This is the core function of ASCL1 as a proneural transcription factor.
Reason: This is a core function. ASCL1 overexpression increases neurogenesis, and it is required for neuronal differentiation in multiple lineages.
Supporting Evidence:
PMID:19008346
By overexpressing one of these, the transcription factor ASCL1, we were able to regain neurogenesis from hNPC(VM) cultures
|
|
GO:0045686
negative regulation of glial cell differentiation
|
TAS
PMID:17166924 Ascl1 defines sequentially generated lineage-restricted neur... |
NEW |
Summary: ASCL1 suppresses glial (astrocyte) fate, promoting neuronal and oligodendrocyte lineages over astroglial lineage. Genetic fate mapping shows ASCL1 is present in progenitors to neurons and oligodendrocytes but not astrocytes.
Reason: ASCL1 actively suppresses gliogenesis (specifically astrocyte differentiation) as part of its role in the neuron-glia binary fate decision. Ascl1-null cells have diminished neuronal differentiation capacity and retain characteristics of immature glial cells (PMID:17166924). This annotation is missing and represents a core function of ASCL1 in lineage specification.
Supporting Evidence:
PMID:17166924
We find that Ascl1 is present in progenitors to both neurons and oligodendrocytes, but not astrocytes.
|
|
GO:0048663
neuron fate commitment
|
IEA
GO_REF:0000107 |
ACCEPT |
Summary: ASCL1 is required for neuron fate commitment, functioning early in neurogenesis to commit progenitors to neuronal lineages.
Reason: Neuron fate commitment is a core function. ASCL1 expression marks the transition from cycling progenitors to postmitotic neurons (PMID:36931659).
Supporting Evidence:
PMID:36931659
endogenous expression of ASCL1 drives progenitor differentiation
|
|
GO:0048665
neuron fate specification
|
IEA
GO_REF:0000107 |
ACCEPT |
Summary: ASCL1 specifies neuronal fate, particularly GABAergic interneurons in the cortex and noradrenergic neurons in the autonomic nervous system.
Reason: Neuron fate specification is a core function. ASCL1 specifies particular neuronal subtypes including GABAergic interneurons (PMID:12050665) and noradrenergic neurons (PMID:14532329).
Supporting Evidence:
PMID:12050665
One lineage expresses Dlx1/2 and Mash1 transcription factors
PMID:14532329
All HASH-1 mutant alleles impaired noradrenergic neuronal development
|
|
GO:0048666
neuron development
|
IEA
GO_REF:0000107 |
ACCEPT |
Summary: ASCL1 is essential for neuron development broadly, encompassing differentiation and maturation.
Reason: Neuron development is a core function. This broader term encompasses the more specific neuronal differentiation and fate commitment functions.
Supporting Evidence:
PMID:10903890
essential for proper development of olfactory and most peripheral autonomic neurons
|
|
GO:0051593
response to folic acid
|
IEA
GO_REF:0000107 |
UNDECIDED |
Summary: This annotation is transferred from model organisms. The functional relevance to human ASCL1 is unclear without supporting literature.
Reason: Unable to verify relevance of folic acid response for human ASCL1 without access to the primary evidence. This may represent a peripheral phenotype from model organisms.
|
|
GO:0060579
ventral spinal cord interneuron fate commitment
|
IEA
GO_REF:0000107 |
ACCEPT |
Summary: ASCL1 functions with FOXN4 in specifying V2b interneurons in the spinal cord, as documented in UniProt and ISS annotations.
Reason: This is a specific neuronal fate commitment function supported by the UniProt record stating ASCL1 acts synergistically with FOXN4 to specify V2b neurons from p2 progenitors.
Supporting Evidence:
UniProt:P50553
Acts synergistically with FOXN4 to specify the identity of V2b neurons rather than V2a from bipotential p2 progenitors during spinal cord neurogenesis
|
|
GO:0061549
sympathetic ganglion development
|
IEA
GO_REF:0000107 |
ACCEPT |
Summary: ASCL1 is required for sympathetic nervous system development, including sympathetic ganglia. This is supported by NAS evidence from PMID:10903890.
Reason: Sympathetic ganglion development is related to the autonomic neuron development function of ASCL1, which is well-documented.
Supporting Evidence:
PMID:10903890
essential for proper development of... most peripheral autonomic neurons
|
|
GO:0070849
response to epidermal growth factor
|
IEA
GO_REF:0000107 |
UNDECIDED |
Summary: This annotation is transferred from model organisms. The functional relevance to human ASCL1 is unclear without supporting literature.
Reason: Unable to verify relevance of EGF response for human ASCL1 without access to primary evidence. May represent regulatory effects on ASCL1 expression rather than a core function.
|
|
GO:0071259
cellular response to magnetism
|
IEA
GO_REF:0000107 |
UNDECIDED |
Summary: This is an unusual annotation likely transferred from a specific study. The functional relevance is unclear and this does not represent a core ASCL1 function.
Reason: This appears to be a highly specific phenotype from model organism studies. Without access to the primary evidence, cannot evaluate the relevance to human ASCL1 function.
|
|
GO:0003676
nucleic acid binding
|
EXP
PMID:28402879 Fragment-Based NMR Study of the Conformational Dynamics in t... |
MARK AS OVER ANNOTATED |
Summary: This NMR study characterized the conformational dynamics of ASCL1 protein. While it confirms DNA binding capacity, the term is too general given the available specific annotations.
Reason: The term "nucleic acid binding" is too general. ASCL1 specifically binds double-stranded DNA at E-box sequences. More specific terms are already annotated with experimental evidence.
Proposed replacements:
E-box binding
sequence-specific double-stranded DNA binding
Supporting Evidence:
PMID:28402879
it is well known that Ascl1 binds DNA as a homo- or heterodimer via its basic helix-loop-helix (bHLH) motif
|
|
GO:1990837
sequence-specific double-stranded DNA binding
|
IDA
PMID:28473536 Impact of cytosine methylation on DNA binding specificities ... |
ACCEPT |
Summary: This high-throughput SELEX study characterized DNA binding specificities of human transcription factors including ASCL1. It confirms sequence-specific binding to E-box motifs.
Reason: This is a core molecular function with direct experimental evidence. The SELEX method provides systematic characterization of DNA binding specificity.
Supporting Evidence:
PMID:28473536
By analysis of 542 human TFs with methylation-sensitive SELEX... we found that there are also many TFs that prefer CpG-methylated sequences
|
|
GO:0000785
chromatin
|
ISA
GO_REF:0000113 |
ACCEPT |
Summary: ASCL1 binds chromatin as a pioneer transcription factor. This annotation from the TFClass database reflects ASCL1's chromatin association.
Reason: ASCL1 associates with chromatin where it binds nucleosomal DNA and recruits chromatin remodelers. The pioneer factor activity (PMID:36931659) supports chromatin localization.
Supporting Evidence:
PMID:36931659
Pioneer transcription factors are thought to play pivotal roles in developmental processes by binding nucleosomal DNA
|
|
GO:0000981
DNA-binding transcription factor activity, RNA polymerase II-specific
|
ISA
GO_REF:0000113 |
ACCEPT |
Summary: This ISA annotation from TFClass is correct and consistent with ASCL1's function as a bHLH transcription factor regulating Pol II-dependent transcription.
Reason: This is a core molecular function. Consistent with IBA annotation and experimental evidence.
Supporting Evidence:
PMID:10903890
The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro, and transactivates an E-box containing reporter construct in vivo.
|
|
GO:0045666
positive regulation of neuron differentiation
|
ISS
GO_REF:0000024 |
ACCEPT |
Summary: ISS annotation consistent with ASCL1's role as a proneural factor promoting neuronal differentiation.
Reason: This is a core function with multiple supporting evidence types. The ISS is consistent with IBA and IEA annotations for the same term.
Supporting Evidence:
PMID:19008346
By overexpressing one of these, the transcription factor ASCL1, we were able to regain neurogenesis
|
|
GO:0030182
neuron differentiation
|
ISS
GO_REF:0000024 |
ACCEPT |
Summary: ISS annotation for neuron differentiation, consistent with multiple other evidence types.
Reason: Core function with abundant supporting evidence across multiple annotation types.
Supporting Evidence:
PMID:10903890
essential for proper development of olfactory and most peripheral autonomic neurons
|
|
GO:0048663
neuron fate commitment
|
ISS
GO_REF:0000024 |
ACCEPT |
Summary: ISS annotation for neuron fate commitment, consistent with ASCL1's proneural function.
Reason: Core function supported by multiple evidence types and extensive literature.
Supporting Evidence:
PMID:36931659
endogenous expression of ASCL1 drives progenitor differentiation
|
|
GO:0048665
neuron fate specification
|
ISS
GO_REF:0000024 |
ACCEPT |
Summary: ISS annotation for neuron fate specification, consistent with ASCL1's role in specifying neuronal subtypes.
Reason: Core function supported by experimental evidence for specific neuronal subtype specification.
Supporting Evidence:
PMID:12050665
One lineage expresses Dlx1/2 and Mash1 transcription factors, represents 65% of neocortical GABAergic neurons
|
|
GO:0048666
neuron development
|
ISS
GO_REF:0000024 |
ACCEPT |
Summary: ISS annotation for neuron development, consistent with ASCL1's essential role in neurogenesis.
Reason: Core function supported by extensive literature and multiple evidence types.
Supporting Evidence:
PMID:10903890
essential for proper development of olfactory and most peripheral autonomic neurons
|
|
GO:0000122
negative regulation of transcription by RNA polymerase II
|
IDA
PMID:11736660 Proprotein convertase PACE4 is down-regulated by the basic h... |
ACCEPT |
Summary: ASCL1 represses PACE4 gene transcription via E-box binding. This demonstrates transcriptional repressor activity in addition to its better-known activator function.
Reason: ASCL1 functions as both activator and repressor depending on target gene and context. The repression of PACE4 is directly demonstrated by this study.
Supporting Evidence:
PMID:11736660
The overexpression of hASH-1 or MASH-1 causes a marked decrease in endogenous PACE4 gene expression
|
|
GO:0000978
RNA polymerase II cis-regulatory region sequence-specific DNA binding
|
IDA
PMID:11736660 Proprotein convertase PACE4 is down-regulated by the basic h... |
ACCEPT |
Summary: ASCL1 binds to the cis-regulatory E-box cluster in the PACE4 promoter to regulate transcription.
Reason: This is a core molecular function with direct experimental evidence from gel shift assays demonstrating binding to the PACE4 promoter E-box cluster.
Supporting Evidence:
PMID:11736660
Binding of hASH-1 to the E-box cluster was confirmed by gel mobility-shift assay
|
|
GO:0001227
DNA-binding transcription repressor activity, RNA polymerase II-specific
|
IDA
PMID:11736660 Proprotein convertase PACE4 is down-regulated by the basic h... |
ACCEPT |
Summary: ASCL1 functions as a transcriptional repressor of the PACE4 gene. This demonstrates context- dependent repressor activity.
Reason: This is a documented molecular function of ASCL1. While primarily known as an activator, ASCL1 can repress specific target genes like PACE4 via E-box binding.
Supporting Evidence:
PMID:11736660
The overexpression of hASH-1 or MASH-1 causes a marked decrease in endogenous PACE4 gene expression
|
|
GO:0060579
ventral spinal cord interneuron fate commitment
|
ISS
GO_REF:0000024 |
ACCEPT |
Summary: ISS annotation consistent with ASCL1's role in V2b interneuron specification in spinal cord.
Reason: Consistent with UniProt annotation describing ASCL1's function with FOXN4 in V2b specification.
Supporting Evidence:
UniProt:P50553
Acts synergistically with FOXN4 to specify the identity of V2b neurons
|
|
GO:0003358
noradrenergic neuron development
|
ISS
GO_REF:0000024 |
ACCEPT |
Summary: ISS annotation consistent with ASCL1's essential role in noradrenergic neuron development.
Reason: Consistent with IMP evidence from PMID:14532329 demonstrating impaired noradrenergic development with ASCL1 mutations.
Supporting Evidence:
PMID:14532329
All HASH-1 mutant alleles impaired noradrenergic neuronal development
|
|
GO:0010468
regulation of gene expression
|
ISS
GO_REF:0000024 |
MARK AS OVER ANNOTATED |
Summary: ASCL1 regulates gene expression as a transcription factor. This is a very general term.
Reason: While correct, this term is too general. More specific terms like "regulation of transcription by RNA polymerase II" are more informative and already annotated.
Proposed replacements:
regulation of transcription by RNA polymerase II
|
|
GO:0061549
sympathetic ganglion development
|
ISS
GO_REF:0000024 |
ACCEPT |
Summary: ISS annotation consistent with ASCL1's role in autonomic nervous system development.
Reason: Consistent with ASCL1's essential role in peripheral autonomic neuron development.
Supporting Evidence:
PMID:10903890
essential for proper development of... most peripheral autonomic neurons
|
|
GO:0045892
negative regulation of DNA-templated transcription
|
IDA
PMID:11736660 Proprotein convertase PACE4 is down-regulated by the basic h... |
ACCEPT |
Summary: ASCL1 negatively regulates transcription of the PACE4 gene. This is a more general term than the Pol II-specific repression annotation.
Reason: This is demonstrated by the PACE4 repression study. Slightly more general than GO:0000122 but both are correct.
Supporting Evidence:
PMID:11736660
The overexpression of hASH-1 or MASH-1 causes a marked decrease in endogenous PACE4 gene expression
|
|
GO:0005634
nucleus
|
IDA
PMID:12858003 Mechanisms of neuroendocrine differentiation in pulmonary ne... |
ACCEPT |
Summary: Nuclear localization demonstrated by immunohistochemistry in pulmonary neuroendocrine cells.
Reason: Core cellular component annotation with direct experimental evidence.
Supporting Evidence:
PMID:12858003
Immunohistochemically, pulmonary neuroendocrine cells (PNECs) are positive for Mash1
|
|
GO:0003359
noradrenergic neuron fate commitment
|
IMP
PMID:14532329 Noradrenergic neuronal development is impaired by mutation o... |
ACCEPT |
Summary: HASH-1 mutations impair noradrenergic neuronal fate commitment, as shown by mutation analysis in CCHS patients and in vitro models.
Reason: Core function with IMP evidence. Mutations in ASCL1 cause noradrenergic neuron development defects, demonstrating its essential role in fate commitment.
Supporting Evidence:
PMID:14532329
All HASH-1 mutant alleles impaired noradrenergic neuronal development, when overexpressed from adenoviral constructs.
|
|
GO:0021892
cerebral cortex GABAergic interneuron differentiation
|
IEP
PMID:12050665 Origin of GABAergic neurons in the human neocortex. |
ACCEPT |
Summary: ASCL1 (Mash1) is expressed in progenitors that give rise to GABAergic interneurons in human neocortex, marking this specific lineage.
Reason: This is a specific neuronal differentiation function supported by expression pattern analysis in human fetal cortex.
Supporting Evidence:
PMID:12050665
One lineage expresses Dlx1/2 and Mash1 transcription factors, represents 65% of neocortical GABAergic neurons in humans, and originates from Mash1-expressing progenitors
|
|
GO:0032526
response to retinoic acid
|
IEP
PMID:12000752 Activation of the phosphatidylinositol 3-kinase/Akt signalin... |
KEEP AS NON CORE |
Summary: ASCL1 expression is rapidly reduced in response to retinoic acid treatment in neuroblastoma cells undergoing differentiation.
Reason: ASCL1 expression responds to retinoic acid (downregulation), but this represents regulation OF ASCL1 rather than a primary function of ASCL1.
Supporting Evidence:
PMID:12000752
expression of neuroblast-specific ASCL1 (HASH-1) gene was promptly reduced after RA treatment
|
|
GO:0043425
bHLH transcription factor binding
|
IPI
PMID:11940670 Notch signaling induces rapid degradation of achaete-scute h... |
ACCEPT |
Summary: ASCL1 interacts with E12, a bHLH transcription factor, and this interaction protects ASCL1 from Notch-induced degradation.
Reason: This is a core molecular function. ASCL1 requires heterodimerization with bHLH E-proteins for DNA binding and stability.
Supporting Evidence:
PMID:11940670
Overexpression of the hASH1-dimerizing partner E12 could protect hASH1 from degradation
|
|
GO:0045665
negative regulation of neuron differentiation
|
IDA
PMID:12000752 Activation of the phosphatidylinositol 3-kinase/Akt signalin... |
REMOVE |
Summary: This annotation seems inconsistent with ASCL1's primary role as a positive regulator of neuronal differentiation. The paper shows ASCL1 is downregulated during differentiation.
Reason: The cited paper (PMID:12000752) shows that ASCL1 expression is reduced during RA-induced differentiation, not that ASCL1 negatively regulates differentiation. ASCL1 is a proneural factor that promotes differentiation. This annotation appears to be an error in interpretation.
Supporting Evidence:
PMID:12000752
expression of neuroblast-specific ASCL1 (HASH-1) gene was promptly reduced after RA treatment
|
|
GO:0060487
lung epithelial cell differentiation
|
NAS
PMID:12858003 Mechanisms of neuroendocrine differentiation in pulmonary ne... |
MODIFY |
Summary: ASCL1 (hASH1) is specifically involved in neuroendocrine differentiation within lung epithelium, not general lung epithelial cell differentiation.
Reason: ASCL1 is specifically required for pulmonary neuroendocrine cell differentiation, not general lung epithelial differentiation. A more specific term would be more accurate.
Proposed replacements:
lung neuroendocrine cell differentiation
Supporting Evidence:
PMID:12858003
Moreover, studies of small cell carcinoma and non- small cell carcinoma suggest that neuroendocrine differentiation could be regulated by hASH1
|
|
GO:0070888
E-box binding
|
IDA
PMID:11736660 Proprotein convertase PACE4 is down-regulated by the basic h... |
ACCEPT |
Summary: ASCL1 binds E-box sequences in the PACE4 promoter, confirmed by gel mobility-shift assay.
Reason: This is a core molecular function with direct experimental evidence.
Supporting Evidence:
PMID:11736660
Binding of hASH-1 to the E-box cluster was confirmed by gel mobility-shift assay
|
|
GO:0003700
DNA-binding transcription factor activity
|
IDA
PMID:10903890 HASH-1 and E2-2 are expressed in human neuroblastoma cells a... |
ACCEPT |
Summary: ASCL1 functions as a transcription factor, binding DNA and transactivating reporter genes.
Reason: Core molecular function with direct experimental evidence from reporter assays.
Supporting Evidence:
PMID:10903890
The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro, and transactivates an E-box containing reporter construct in vivo
|
|
GO:0043425
bHLH transcription factor binding
|
IPI
PMID:10903890 HASH-1 and E2-2 are expressed in human neuroblastoma cells a... |
ACCEPT |
Summary: ASCL1 interacts with E2-2 (TCF4), a bHLH transcription factor, demonstrated by yeast two-hybrid and co-immunoprecipitation.
Reason: Core molecular function. Heterodimerization with E-proteins is essential for ASCL1 DNA binding and transcriptional activity.
Supporting Evidence:
PMID:10903890
E2-2 interacts with HASH-1 in both yeast and mammalian cells
|
|
GO:0045944
positive regulation of transcription by RNA polymerase II
|
IDA
PMID:10903890 HASH-1 and E2-2 are expressed in human neuroblastoma cells a... |
ACCEPT |
Summary: ASCL1 transactivates E-box containing reporter genes when complexed with E-proteins.
Reason: Core function with direct experimental evidence from reporter assays.
Supporting Evidence:
PMID:10903890
transactivates an E-box containing reporter construct in vivo
|
|
GO:0048485
sympathetic nervous system development
|
NAS
PMID:10903890 HASH-1 and E2-2 are expressed in human neuroblastoma cells a... |
ACCEPT |
Summary: ASCL1 is essential for development of peripheral autonomic neurons, which includes the sympathetic nervous system.
Reason: This is a core biological process supported by the evidence for autonomic neuron development.
Supporting Evidence:
PMID:10903890
essential for proper development of... most peripheral autonomic neurons
|
|
GO:0070888
E-box binding
|
IDA
PMID:10903890 HASH-1 and E2-2 are expressed in human neuroblastoma cells a... |
ACCEPT |
Summary: ASCL1/E2-2 complex binds E-box sequence (CACCTG) demonstrated by in vitro binding assays.
Reason: Core molecular function with direct experimental evidence. Duplicate entry with different reference supporting the same function.
Supporting Evidence:
PMID:10903890
The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro
|
|
GO:0007219
Notch signaling pathway
|
IDA
PMID:16160079 Conservation of the Notch1 signaling pathway in gastrointest... |
ACCEPT |
Summary: ASCL1 is regulated by and functions within the Notch signaling pathway. Notch1 activation represses ASCL1 expression.
Reason: ASCL1 is a key component of the Notch signaling pathway, acting downstream of Notch (repressed by active Notch). It also activates DLL1/DLL3 which modulate Notch signaling.
Supporting Evidence:
PMID:16160079
Notch1 pathway activation led to an increase in hairy enhancer of split 1 (HES-1) protein and a concomitant silencing of human Notch1/HES-1/achaete-scute homolog 1
PMID:11940670
Notch signaling induces rapid degradation of achaete-scute homolog 1
|
|
GO:0005634
nucleus
|
IDA
PMID:17507989 Achaete-scute homolog-1 linked to remodeling and preneoplasi... |
ACCEPT |
Summary: Nuclear localization demonstrated by immunohistochemistry and functional studies.
Reason: Core cellular component with direct experimental evidence. Multiple IDA entries support this.
Supporting Evidence:
PMID:17507989
Constitutive expression of human ASH-1 (hASH1) in mouse lung
|
|
GO:0005634
nucleus
|
IDA
PMID:18311112 Human ASH1 expression in prostate cancer with neuroendocrine... |
ACCEPT |
Summary: Nuclear localization demonstrated by immunohistochemistry in prostate cancer cells with neuroendocrine differentiation.
Reason: Core cellular component with direct experimental evidence.
Supporting Evidence:
PMID:18311112
Human ASH1 protein was analyzed by immunohistochemistry
|
|
GO:0022008
neurogenesis
|
IDA
PMID:19008346 Regionally specified human neural progenitor cells derived f... |
ACCEPT |
Summary: ASCL1 overexpression increases neurogenesis in human neural progenitor cells.
Reason: Core biological process with direct experimental evidence showing increased neuron production upon ASCL1 overexpression.
Supporting Evidence:
PMID:19008346
By overexpressing one of these, the transcription factor ASCL1, we were able to regain neurogenesis from hNPC(VM) cultures
|
|
GO:0043066
negative regulation of apoptotic process
|
IMP
PMID:17507989 Achaete-scute homolog-1 linked to remodeling and preneoplasi... |
KEEP AS NON CORE |
Summary: ASCL1 expression confers resistance to apoptosis in lung epithelial cells. Knockdown increases apoptosis in lung cancer cells.
Reason: This is a documented function of ASCL1 but represents a downstream effect rather than a primary function. It is relevant to ASCL1's role in cancer but not its core developmental neurogenesis function.
Supporting Evidence:
PMID:17507989
Knockdown of hASH1 gene in human lung cancer cells in vitro suppressed growth by increasing apoptosis. We also show that forced expression of hASH1 in immortalized human bronchial epithelial cells decreases apoptosis.
|
Q: What are the specific chromatin targets where ASCL1 acts as a classical pioneer factor versus requiring mSWI/SNF cooperation?
Q: How does ASCL1 function as both activator and repressor depending on target gene context?
Q: What determines whether ASCL1 homodimerizes versus heterodimerizes with specific E-proteins?
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organism: human
gene_id: ASCL1
gene_symbol: ASCL1
uniprot_accession: P50553
protein_description: 'RecName: Full=Achaete-scute homolog 1 {ECO:0000303|PubMed:8390674};
Short=ASH-1 {ECO:0000303|PubMed:8390674}; Short=hASH1 {ECO:0000303|PubMed:8390674};
AltName: Full=Class A basic helix-loop-helix protein 46 {ECO:0000312|HGNC:HGNC:738};
Short=bHLHa46 {ECO:0000312|HGNC:HGNC:738};'
gene_info: Name=ASCL1 {ECO:0000312|HGNC:HGNC:738}; Synonyms=ASH1, BHLHA46 {ECO:0000312|HGNC:HGNC:738},
HASH1 {ECO:0000303|PubMed:8390674};
organism_full: Homo sapiens (Human).
protein_family: Not specified in UniProt
protein_domains: bHLH_dom. (IPR011598); HLH_DNA-bd_sf. (IPR036638); MASH1/Ascl1a-like.
(IPR015660); HLH (PF00010)
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BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.
DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'ASCL1' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information
Please provide a comprehensive research report on the gene ASCL1 (gene ID: ASCL1, UniProt: P50553) in human.
The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
ASCL1 (Achaete-Scute Family bHLH Transcription Factor 1), also known as ASH1, HASH1, or MASH1, is a basic helix-loop-helix (bHLH) transcription factor that serves as a master regulator of neuronal differentiation and neuroendocrine cell development in humans and other vertebrates. The human gene maps to chromosome 12q23.2 and encodes a 238-amino acid protein that shares 95% identity with the mouse ortholog Mash1 [ball-1993-human-cloning-summary]. As a vertebrate homolog of the Drosophila achaete-scute complex (AS-C) genes, ASCL1 exemplifies the evolutionary conservation of proneural gene function from invertebrates to mammals [guillemot-1993-knockout-mouse-summary].
The primary molecular function of ASCL1 is sequence-specific DNA binding and transcriptional activation. ASCL1 recognizes and binds to E-box consensus sequences (5'-CANNTG-3') in target gene regulatory regions, with a strong preference for the CAGCTG variant [castro-2011-progenitor-proliferation-summary][aydin-2019-neuronal-subtype-summary]. Efficient DNA binding requires heterodimerization with ubiquitously expressed E-proteins, particularly TCF3 (E12/E47), TCF4, and TCF12, through the helix-loop-helix domain. Beyond its classical transcription factor role, ASCL1 functions as a pioneer transcription factor, capable of accessing closed chromatin and initiating chromatin remodeling to enable binding of downstream factors [raposo-2015-chromatin-landscape-summary][wapinski-2013-reprogramming-hierarchy-summary]. This pioneer activity underlies ASCL1's remarkable ability to direct cell fate decisions in both developmental and reprogramming contexts.
The ASCL1 protein contains several functionally important domains. The basic region mediates direct DNA contact, while the helix-loop-helix domain enables dimerization with E-protein partners. Additionally, a C-terminal acidic domain and an N-terminal glutamine/alanine-rich region contribute to transcriptional activity, though the N-terminal polyalanine tract (encoded by CAG repeats) appears dispensable for neuronal differentiation [ball-1993-human-cloning-summary]. Structure-function studies have identified a nuclear localization signal and demonstrated that specific mutations within the basic region block DNA binding but not heterodimer formation with TCF3 and TCF12.
High-resolution NMR studies have provided the first atomic-level structural characterization of ASCL1, revealing that it forms an extended polypeptide chain lacking persistent tertiary interactions [toto-2017-nmr-structure-summary]. The N-terminal polyalanine stretch (13 alanines) adopts a stable α-helical conformation, while the adjacent polyglutamine region shows gradual helical destabilization and functions as a transition zone. Critically, the bHLH domain in its DNA-free state contains two transient helical segments (H1 and H2) separated by a flexible kink, with the C-terminal helix showing greater stability. This structural disorder in the absence of DNA is consistent with findings from related bHLH proteins such as MyoD and E47, where DNA binding induces a stable dimeric conformation. The C-terminal region of ASCL1 remains highly disordered and contains the multiple serine-proline phosphorylation sites that regulate its activity. No crystal structure of ASCL1 bound to DNA has been solved, but structures of related bHLH proteins (MyoD-DNA at 2.8 Å resolution) indicate that the bHLH domain forms a parallel four-helix bundle upon DNA engagement.
ASCL1 exhibits distinct E-box sequence preferences that distinguish it from other proneural factors. De novo motif analysis of ChIP-seq data revealed that the CAGCTG E-box motif is highly enriched directly beneath 74% of ASCL1 binding peaks [castro-2011-progenitor-proliferation-summary]. This "GC" core E-box preference contrasts with Neurogenin 2 (Neurog2), which preferentially binds CAGATG/CADATG motifs [aydin-2019-neuronal-subtype-summary]. E-proteins enhance ASCL1 binding to CAGSTG sequences through heterodimer formation, with the E-protein partner influencing the binding conformation at the adjacent half-site. This sequence selectivity has important biological implications: when expressed in embryonic stem cells or fibroblasts, ASCL1 and Neurog2 bind largely non-overlapping genomic sites and specify different neuronal subtypes—ASCL1 drives GABAergic and sympathetic neuronal fates while Neurog2 promotes glutamatergic and sensory neuronal identities [aydin-2019-neuronal-subtype-summary].
Genome-wide studies have mapped over 21,000 ASCL1 binding sites, predominantly at distal enhancers (approximately 63% in intergenic regions) rather than promoters (only ~7%) [raposo-2015-chromatin-landscape-summary]. This enhancer-centric binding pattern reflects ASCL1's role in establishing cell-type-specific regulatory landscapes. Direct target gene analysis identified 272 high-confidence targets organized into temporal clusters during differentiation, with early targets involved in signal transduction and later targets encoding transcription factors and cytoskeletal proteins essential for neuronal development.
One of the most significant discoveries about ASCL1 is its function as a pioneer transcription factor—a factor capable of binding nucleosomal DNA in closed chromatin and initiating chromatin remodeling. Unlike conventional transcription factors that require pre-accessible binding sites, pioneer factors can engage condensed chromatin and catalyze the transition to an open, transcriptionally permissive state [raposo-2015-chromatin-landscape-summary].
Studies of ASCL1-mediated neuronal reprogramming revealed that ASCL1 binds chromatin marked by a unique "trivalent" signature combining H3K9me3, H3K27ac, and H3K4me1 histone modifications [wapinski-2013-reprogramming-hierarchy-summary]. At these sites, ASCL1 binding precedes increases in chromatin accessibility and the appearance of new DNase hypersensitivity sites. Importantly, the chromatin accessibility at ASCL1 binding sites remains largely unchanged throughout neural stem cell differentiation, as ASCL1 targets both readily accessible and closed chromatin in proliferating cells.
Recent work has refined our understanding of ASCL1's pioneer activity, revealing that it operates through two distinct mechanisms depending on genomic context [ali-2020-mswi-snf-summary]. At approximately 23.5% of its dependent sites, ASCL1 functions as a classical pioneer factor, binding closed chromatin independently. However, at roughly 68% of sites, ASCL1 requires cooperation with the mSWI/SNF chromatin remodeling complex. Physical interactions between ASCL1 and mSWI/SNF subunits SMARCC1 and ARID1A have been confirmed by co-immunoprecipitation and proximity ligation assays in both cultured cells and human fetal cortex tissue. Notably, ASCL1 lacks intrinsic chromatin remodeling enzymatic activity and depends on recruitment of cofactors for this function.
The hierarchical mechanism of ASCL1-mediated reprogramming has been elegantly demonstrated in the direct conversion of fibroblasts to neurons. When the three factors ASCL1, BRN2, and MYT1L are co-expressed, ASCL1 rapidly occupies its cognate sites genome-wide, with binding patterns virtually identical whether ASCL1 is expressed alone or with its partners [wapinski-2013-reprogramming-hierarchy-summary]. BRN2, in contrast, cannot productively access fibroblast chromatin on its own but is recruited to ASCL1-opened sites. This establishes a clear hierarchy: ASCL1 acts first to open chromatin, enabling subsequent binding of BRN2 and activation of the full neurogenic program.
ASCL1 localizes to both the nucleus and cytoplasm of neural stem cells, with comparable distribution patterns in proliferating and differentiating conditions. Cellular fractionation studies detected ASCL1 protein at similar levels in cytoplasmic, nuclear, and chromatin-bound fractions. The protein contains a nuclear localization signal that enables translocation to the nucleus, where it carries out its transcriptional functions [ali-2020-mswi-snf-summary].
Importantly, subcellular localization modulates ASCL1 stability through compartment-specific ubiquitylation [urbanska-2022-phosphorylation-summary]. Chromatin-bound ASCL1 associates with short ubiquitin chains and exhibits greater than double the half-life of cytoplasmic ASCL1, which harbors much longer ubiquitin chains targeting it for proteasomal destruction. The E3 ubiquitin ligase HUWE1, which localizes exclusively to the cytoplasm, mediates cytoplasmic ASCL1 degradation by conjugating ubiquitin to lysines within the bHLH domain. HUWE1 knockdown leads to increased chromatin-bound ASCL1, presumably because stabilized cytoplasmic protein shuttles to the nucleus. This compartmentalized regulation provides a mechanism for fine-tuning ASCL1 activity levels.
ASCL1 activity is regulated by multisite phosphorylation on serine-proline (SP) sites, which functions as a molecular "rheostat" controlling neurogenic potential [urbanska-2022-phosphorylation-summary]. Human ASCL1 contains five key SP sites (S93, S190, S194, S207, S223) that are phosphorylated by proline-directed serine-threonine kinases including CDK-cyclin complexes, ERK, and GSK3. The CDK2-CyclinA2 complex directly phosphorylates ASCL1 during the cell cycle, as demonstrated by mobility shift on SDS-PAGE that is reversed by phosphatase treatment.
Phosphorylation has profound functional consequences. Highly phosphorylated ASCL1 exhibits reduced DNA binding and diminished transcriptional activity. In cancer cells, maintaining ASCL1 in a phosphorylated state allows continued proliferation despite ASCL1 expression. Conversely, a phospho-mutant form of ASCL1 (with SP sites mutated to alanine, termed "5SA") shows substantially enhanced neuronal induction activity both in vitro and in vivo. This un(der)phosphorylated ASCL1 is also resistant to inhibition by Notch signaling and CDK activity [urbanska-2022-phosphorylation-summary].
Phosphorylation also primes ASCL1 for degradation. E-protein (TCF3) binding protects ASCL1 from degradation, and during mitosis, TCF3 dissociation from ASCL1 accelerates its degradation through HUWE1-mediated ubiquitylation. This cell cycle-coupled regulation ensures that ASCL1 protein levels fluctuate appropriately during the proliferation-differentiation decision.
A breakthrough in understanding ASCL1 function came from studies of its expression dynamics. Time-lapse imaging of neural progenitors revealed that ASCL1 levels oscillate with a period of 2-3 hours, driven by oscillations in the Notch pathway effector Hes1 [imayoshi-2013-oscillatory-summary]. Hes1 directly represses ASCL1 transcription, and its inherent instability creates alternating states of high and low Hes1 levels. When Hes1 is low, ASCL1 rises and activates Delta-like ligands (DLL1, DLL3), which trigger Notch signaling in neighboring cells and perpetuate the oscillatory cycle.
The critical insight is that expression dynamics—not just expression levels—determine cell fate outcomes [imayoshi-2013-oscillatory-summary][castro-2011-progenitor-proliferation-summary]. Oscillatory ASCL1 expression at lower levels maintains proliferating neural progenitors, while sustained expression at higher levels drives neuronal differentiation. Optogenetic experiments confirmed this model: artificially sustaining ASCL1 expression promoted neuronal fate determination, whereas oscillatory expression maintained the progenitor state. This resolves the apparent paradox of ASCL1 promoting both proliferation and differentiation in different contexts—the outcome depends on how ASCL1 is expressed, not simply whether it is expressed.
ASCL1 is essential for the development of multiple neuronal populations in both the central and peripheral nervous systems. Knockout mouse studies established that Mash1-null animals survive until birth but die shortly after due to breathing and feeding defects [guillemot-1993-knockout-mouse-summary]. While the brain and spinal cord appear grossly normal, severe developmental abnormalities affect the olfactory epithelium, sympathetic ganglia, parasympathetic ganglia, and enteric ganglia. In the olfactory system, ASCL1 acts as a determination gene—Mash1-null embryos fail to produce olfactory sensory neurons because progenitors are not specified and the Notch pathway is not properly activated.
In the peripheral nervous system, ASCL1 biases neural crest cells toward the autonomic lineage rather than the sensory lineage [aydin-2019-neuronal-subtype-summary]. Loss of ASCL1 produces significantly smaller sympathetic ganglia due to impaired progenitor proliferation, though noradrenergic neurons can eventually form after a developmental delay, suggesting partial compensation by other factors. The transcription factor network governing sympathetic ganglia development involves BMP signals from the dorsal aorta that activate Phox2b, ASCL1, Hand2, and GATA factors in a coordinated program.
In the central nervous system, ASCL1's transient expression coordinates the transition from proliferating progenitors to differentiating neurons [castro-2011-progenitor-proliferation-summary]. Genome-wide target analysis revealed that ASCL1 directly controls genes involved in neural progenitor specification, cell cycle progression, neuronal differentiation, axon guidance, and synapse formation. Surprisingly, ASCL1 regulates numerous cell cycle genes including canonical regulators and oncogenic transcription factors, establishing that it is required for normal neural progenitor proliferation—an unexpected function for a proneural gene traditionally associated with cell cycle exit.
In the enteric nervous system (ENS), which controls gut motility and function, ASCL1 plays a critical role in specifying particular neuronal subtypes [memic-2016-ens-subtypes-summary]. All enteric neuronal subtypes and enteric glia appear to derive from ASCL1-expressing progenitors. In Ascl1-knockout mice, neural crest-derived cells colonize the bowel but develop into a sparse and abnormal ganglionic network. Specific neuronal populations are differentially affected: neurons expressing calbindin, tyrosine hydroxylase (TH), and vasoactive intestinal peptide (VIP) are selectively decreased, while serotonergic neurons form in normal numbers. Notably, esophageal neurons fail to form entirely. ASCL1 operates within a transcription factor network involving SOX10 and PHOX2B—SOX10 initially induces both PHOX2B and ASCL1 expression, and then ASCL1 suppresses SOX10 to commit cells toward neuronal rather than glial fate. These findings explain why ASCL1 mutations have been identified in patients with Ondine's curse (congenital central hypoventilation syndrome with Hirschsprung disease), highlighting the gene's importance for proper ENS development.
ASCL1 is a central node in the Notch signaling pathway, which orchestrates lateral inhibition during neurogenesis. ASCL1 activates expression of Notch ligands DLL1 and DLL3, which bind Notch receptors on neighboring cells [borromeo-2016-sclc-heterogeneity-summary]. Notch activation releases the intracellular domain (NICD), which together with RBPJ upregulates Hes1, Hes5, and Hes6. These Hes proteins then directly repress ASCL1 and other proneural bHLH factors, completing the negative feedback loop.
Through this lateral inhibition mechanism, cells expressing high ASCL1 inhibit their neighbors from differentiating, maintaining the progenitor pool while allowing a subset of cells to commit to neuronal fate. The balance between ASCL1 and Hes factors determines whether cells remain as progenitors or differentiate. Genetic disruption of this balance—for example, by deleting Notch1, RBPJ, or Hes genes—results in premature ASCL1 expression and precocious neuronal differentiation.
ASCL1 also regulates DLL3, which differs from other Delta ligands in that it acts cell-autonomously rather than in trans [borromeo-2016-sclc-heterogeneity-summary]. DLL3 has emerged as a therapeutic target in SCLC precisely because of its specific regulation by ASCL1 in neuroendocrine contexts.
ASCL1 is aberrantly expressed in several neuroendocrine cancers, most prominently small cell lung cancer (SCLC), where it functions as a lineage oncogene [augustyn-2014-lineage-oncogene-summary][borromeo-2016-sclc-heterogeneity-summary]. SCLC is an aggressive malignancy accounting for approximately 15% of lung cancers, and approximately 75% of SCLC tumors express high levels of ASCL1. This expression is not merely a marker but is functionally essential—ASCL1 knockdown induces apoptosis specifically in ASCL1-positive cancer lines while sparing ASCL1-negative cells.
Molecular subtyping has classified SCLC into four main categories based on transcription factor expression: ASCL1-high (SCLC-A, ~75%), NEUROD1-high (SCLC-N, ~15%), POU2F3-high (SCLC-P), and YAP1-high (SCLC-Y) [borromeo-2016-sclc-heterogeneity-summary]. The ASCL1 and NEUROD1 subtypes exhibit neuroendocrine features, while the others do not. ChIP-seq studies revealed that ASCL1 and NEUROD1 occupy largely non-overlapping genomic sites, with only 304 of approximately 10,000 sites shared. ASCL1 directly targets known SCLC oncogenes including MYCL1, RET, SOX2, and NFIB, while NEUROD1 targets MYC.
Mouse genetic models confirmed that only ASCL1 (not NEUROD1) is required for SCLC tumor formation [borromeo-2016-sclc-heterogeneity-summary]. ASCL1 is present in normal pulmonary neuroendocrine cells, the cell of origin for SCLC, while NEUROD1 is absent. This establishes ASCL1 as the essential lineage-defining factor for the majority of SCLC cases.
The oncogenic function of ASCL1 involves maintaining "lineage survival" through regulation of anti-apoptotic programs [augustyn-2014-lineage-oncogene-summary]. A key target is BCL2, which contains conserved E-box binding sites occupied by ASCL1 in SCLC cells. ASCL1 knockdown reduces BCL2 expression, while BCL2 inhibitor treatment shows 10-30 fold greater efficacy in ASCL1-positive versus ASCL1-negative tumors. A 72-gene ASCL1 signature derived from ChIP-seq analysis predicts poor prognosis in resected NSCLC specimens and includes 24 potentially druggable targets, providing a molecular framework for targeted therapy development.
Neuroblastoma, a pediatric cancer of the sympathetic nervous system, provides another context where ASCL1's dual proliferation-differentiation functions become dysregulated. Neuroblastoma is believed to arise from sympathetic neuroblast precursors that fail to engage the neuronal differentiation program, becoming locked in a pro-proliferative developmental state [wang-2019-neuroblastoma-crc-summary]. ASCL1 is a member of the core regulatory circuitry (CRC) that defines the adrenergic (ADRN) subtype of neuroblastoma, alongside PHOX2A, PHOX2B, HAND2, and GATA3. These transcription factors form an interconnected autoregulatory loop that maintains neuroblast identity.
In neuroblastoma, ASCL1 expression is aberrantly maintained and the protein is largely phosphorylated on multiple serine-proline sites. This phosphorylation state prevents terminal differentiation while allowing continued proliferation. MYCN, a key oncogenic driver in aggressive neuroblastoma, directly regulates ASCL1 expression, and LMO1 acts as a coregulator in this circuitry [wang-2019-neuroblastoma-crc-summary]. CRISPR-mediated deletion of ASCL1 in neuroblastoma cells results in slower growth, confirming that ASCL1 contributes to the rapid proliferation of both MYCN-amplified and non-amplified tumors.
Importantly, preventing CDK-dependent phosphorylation of ASCL1 in neuroblastoma cells drives coordinated suppression of the MYC-driven core circuit while simultaneously activating a differentiation program leading to mitotic exit. Recent studies using cell cycle phase-specific analysis revealed that ASCL1 binds different genomic targets depending on cell cycle stage: in S/G2/M phases, ASCL1 binds promoters of pro-mitotic genes, while in G1 phase, ASCL1 primes pro-neuronal enhancer loci. Prolonged G1 arrest is required to fully activate ASCL1-bound neuronal enhancers and drive differentiation. These findings suggest that CDK4/6 inhibitors, which extend G1 phase, may be therapeutic in neuroblastoma by allowing ASCL1 to engage its pro-differentiation rather than pro-proliferation program.
The discovery that ASCL1, together with BRN2 and MYT1L, can directly convert fibroblasts to functional neurons without passing through a pluripotent state opened new avenues in regenerative medicine [vierbuchen-2010-neuronal-conversion-summary]. These induced neuronal (iN) cells express neuron-specific proteins, generate action potentials, and form functional synapses. Subsequent studies showed that ASCL1 alone is sufficient to induce immature iN cells, establishing it as the key reprogramming driver, with BRN2 and MYT1L enhancing efficiency and maturation.
The ability of ASCL1 to reprogram diverse cell types—including fibroblasts, hepatocytes, astrocytes, and lymphoid cells—reflects its pioneer factor activity and capacity to access closed chromatin in non-neural contexts [wapinski-2013-reprogramming-hierarchy-summary]. However, the efficiency varies dramatically between cell types, correlating with the presence of the trivalent chromatin signature at neurogenic loci. Cells lacking this signature are refractory to ASCL1-mediated conversion.
Therapeutic applications of ASCL1-mediated reprogramming are being explored for neurodegenerative diseases. In glioblastoma, high ASCL1 expression identifies cells with latent neuronal differentiation capacity that can be induced to terminally differentiate by Notch inhibition, potentially reducing tumorigenicity. In the retina, ASCL1 expression in Muller glia promotes regeneration following injury, though this capacity is modulated by STAT signaling and developmental context.
Beyond cancer, ASCL1 variants have been associated with congenital central hypoventilation syndrome (CCHS) and Haddad syndrome (CCHS combined with Hirschsprung disease), though the primary causative gene for these disorders is PHOX2B. Three ASCL1 variants initially reported in CCHS patients—including polyalanine tract contractions—have been reclassified as variants of uncertain significance because polyalanine contractions are not established pathogenic mechanisms and patients typically also carried PHOX2B mutations.
ASCL1 has diagnostic utility as a marker for neuroendocrine tumors. It is highly expressed in medullary thyroid cancer, small cell lung cancer, and other neuroendocrine carcinomas, and can help distinguish esthesioneuroblastoma from other sinonasal tumors. Expression in normal adult tissues is minimal, restricted primarily to scattered neuroendocrine cells.
Several important questions about ASCL1 biology remain unresolved:
Chromatin Context Determinants: What factors determine whether ASCL1 can access and remodel chromatin at specific genomic sites? The trivalent signature provides a partial answer, but the molecular basis for cell-type-specific permissiveness remains incompletely understood.
Therapeutic Targeting: Can ASCL1 be directly targeted for cancer therapy? As a transcription factor, ASCL1 lacks conventional drug binding pockets. Current approaches focus on downstream targets (BCL2, DLL3) or upstream regulation (CDK inhibitors to modulate phosphorylation status).
Subtype Switching: What determines whether SCLC tumors express ASCL1 or NEUROD1? Evidence suggests that tumors can switch subtypes during progression or treatment, with implications for therapeutic response.
Reprogramming Efficiency: Why does ASCL1-mediated reprogramming work efficiently in some cell types but not others? Understanding the barriers could enable therapeutic reprogramming strategies for neurological diseases.
Oscillation Control: How is the period and amplitude of ASCL1 oscillations regulated, and can these parameters be manipulated to control neural stem cell behavior?
Post-translational Modifications: Beyond phosphorylation and ubiquitylation, what other modifications regulate ASCL1 function? The short ubiquitin chains on chromatin-bound ASCL1 suggest non-degradative ubiquitin functions that warrant investigation.
[ball-1993-human-cloning-summary] Ball DW, et al. Identification of a human achaete-scute homolog highly expressed in neuroendocrine tumors. Proc Natl Acad Sci USA. 1993;90(12):5648-52. PMID: 8390674. DOI: 10.1073/pnas.90.12.5648
[guillemot-1993-knockout-mouse-summary] Guillemot F, et al. Mammalian achaete-scute homolog 1 is required for the early development of olfactory and autonomic neurons. Cell. 1993;75(3):463-76. PMID: 8221886. DOI: 10.1016/0092-8674(93)90381-y
[vierbuchen-2010-neuronal-conversion-summary] Vierbuchen T, et al. Direct conversion of fibroblasts to functional neurons by defined factors. Nature. 2010;463(7284):1035-41. PMID: 20107439. DOI: 10.1038/nature08797
[castro-2011-progenitor-proliferation-summary] Castro DS, et al. A novel function of the proneural factor Ascl1 in progenitor proliferation identified by genome-wide characterization of its targets. Genes Dev. 2011;25(9):930-45. PMID: 21536733. PMC: PMC3084027. DOI: 10.1101/gad.627811
[wapinski-2013-reprogramming-hierarchy-summary] Wapinski OL, et al. Hierarchical mechanisms for direct reprogramming of fibroblasts to neurons. Cell. 2013;155(3):621-35. PMID: 24243019. PMC: PMC3871197. DOI: 10.1016/j.cell.2013.09.028
[imayoshi-2013-oscillatory-summary] Imayoshi I, et al. Oscillatory control of factors determining multipotency and fate in mouse neural progenitors. Science. 2013;342(6163):1203-8. PMID: 24179156. DOI: 10.1126/science.1242366
[augustyn-2014-lineage-oncogene-summary] Augustyn A, et al. ASCL1 is a lineage oncogene providing therapeutic targets for high-grade neuroendocrine lung cancers. Proc Natl Acad Sci USA. 2014;111(41):14788-93. PMID: 25267614. PMC: PMC4205603. DOI: 10.1073/pnas.1410419111
[raposo-2015-chromatin-landscape-summary] Raposo AASF, et al. Ascl1 Coordinately Regulates Gene Expression and the Chromatin Landscape during Neurogenesis. Cell Rep. 2015;10(10):1544-56. PMID: 25753420. PMC: PMC5383937. DOI: 10.1016/j.celrep.2015.02.025
[borromeo-2016-sclc-heterogeneity-summary] Borromeo MD, et al. ASCL1 and NEUROD1 Reveal Heterogeneity in Pulmonary Neuroendocrine Tumors and Regulate Distinct Genetic Programs. Cell Rep. 2016;16(5):1259-1272. PMID: 27452466. PMC: PMC4972690. DOI: 10.1016/j.celrep.2016.06.081
[aydin-2019-neuronal-subtype-summary] Aydin B, et al. Proneural factors Ascl1 and Neurog2 contribute to neuronal subtype identities by establishing distinct chromatin landscapes. Nat Neurosci. 2019;22(6):897-908. PMID: 31086315. PMC: PMC6556771. DOI: 10.1038/s41593-019-0399-y
[urbanska-2022-phosphorylation-summary] Related papers: Ali F, et al. The phosphorylation status of Ascl1 is a key determinant of neuronal differentiation. Development. 2014;141(11):2216-24. PMID: 24821983; Urbanska M, et al. Distinct Regulation of ASCL1 by the Cell Cycle and Chemotherapy in Small Cell Lung Cancer. Mol Cancer Res. 2024;22(7):613-628. PMC: PMC11217739
[ali-2020-mswi-snf-summary] Ali FR, et al. Pioneer factor ASCL1 cooperates with the mSWI/SNF complex at distal regulatory elements to regulate human neural differentiation. Genes Dev. 2023;37(5-6):218-242. PMID: 36931659. PMC: PMC10111863. DOI: 10.1101/gad.350269.122
[toto-2017-nmr-structure-summary] Toto A, et al. Fragment-Based NMR Study of the Conformational Dynamics in the bHLH Transcription Factor Ascl1. Biophys J. 2017;112(1):48-54. PMID: 28076814. PMC: PMC5390047. DOI: 10.1016/j.bpj.2016.11.3196
[memic-2016-ens-subtypes-summary] Memic F, et al. Ascl1 Is Required for the Development of Specific Neuronal Subtypes in the Enteric Nervous System. J Neurosci. 2016;36(15):4339-50. PMID: 27076431. PMC: PMC6601778. DOI: 10.1523/JNEUROSCI.0048-16.2016
[wang-2019-neuroblastoma-crc-summary] Wang L, et al. ASCL1 is a MYCN- and LMO1-dependent member of the adrenergic neuroblastoma core regulatory circuitry. Nat Commun. 2019;10(1):5622. PMID: 31811134. PMC: PMC6898709. DOI: 10.1038/s41467-019-13515-5
NCBI Gene Entry: https://www.ncbi.nlm.nih.gov/gene/429
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template_file: templates/gene_research_go_focused.md
template_variables:
organism: human
gene_id: ASCL1
gene_symbol: ASCL1
uniprot_accession: P50553
protein_description: 'RecName: Full=Achaete-scute homolog 1 {ECO:0000303|PubMed:8390674};
Short=ASH-1 {ECO:0000303|PubMed:8390674}; Short=hASH1 {ECO:0000303|PubMed:8390674};
AltName: Full=Class A basic helix-loop-helix protein 46 {ECO:0000312|HGNC:HGNC:738};
Short=bHLHa46 {ECO:0000312|HGNC:HGNC:738};'
gene_info: Name=ASCL1 {ECO:0000312|HGNC:HGNC:738}; Synonyms=ASH1, BHLHA46 {ECO:0000312|HGNC:HGNC:738},
HASH1 {ECO:0000303|PubMed:8390674};
organism_full: Homo sapiens (Human).
protein_family: Not specified in UniProt
protein_domains: bHLH_dom. (IPR011598); HLH_DNA-bd_sf. (IPR036638); MASH1/Ascl1a-like.
(IPR015660); HLH (PF00010)
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BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.
DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'ASCL1' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information
Please provide a comprehensive research report on the gene ASCL1 (gene ID: ASCL1, UniProt: P50553) in human.
The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
Question: You are an expert researcher providing comprehensive, well-cited information.
Provide detailed information focusing on:
1. Key concepts and definitions with current understanding
2. Recent developments and latest research (prioritize 2023-2024 sources)
3. Current applications and real-world implementations
4. Expert opinions and analysis from authoritative sources
5. Relevant statistics and data from recent studies
Format as a comprehensive research report with proper citations. Include URLs and publication dates where available.
Always prioritize recent, authoritative sources and provide specific citations for all major claims.
BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.
DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'ASCL1' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information
Please provide a comprehensive research report on the gene ASCL1 (gene ID: ASCL1, UniProt: P50553) in human.
The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
Plan overview and identity verification
- Identity check: The target is human ASCL1 (achaete-scute family bHLH transcription factor 1), UniProt P50553, a nuclear basic helix–loop–helix (bHLH) transcription factor also known as MASH1/hASH1. Literature and recent studies consistently describe ASCL1 as a proneural bHLH factor with nuclear localization and canonical bHLH DNA-binding/HLH dimerization domains, matching the UniProt domain annotations (bHLH_dom; HLH_DNA-bd superfamily). These features and nomenclature align with the human protein specified by the user (https://doi.org/10.1158/1541-7786.mcr-23-0405, Mar 2024; https://doi.org/10.1097/cm9.0000000000002693, Sep 2024) (liu2024distinctregulationof pages 1-2, guo2024molecularclassificationof pages 1-2).
Key concepts and definitions with current understanding
- Molecular identity and cellular localization: ASCL1 is a class A bHLH transcription factor that binds E-box motifs (CANNTG) as a heterodimer with E-proteins (e.g., TCF3/E12/E47). It functions in the nucleus to drive neuronal and neuroendocrine gene programs (https://doi.org/10.1158/1541-7786.mcr-23-0405) (liu2024distinctregulationof pages 1-2).
- Molecular function and pioneer-like activity: ASCL1 exhibits pioneer-factor properties, binding nucleosome-occupied DNA and promoting chromatin opening at neuronal enhancers to initiate lineage programs. Its binding is enriched at E-box–dense enhancers, and E-protein association facilitates nucleosomal engagement (https://doi.org/10.1098/rsob.250018, Jun 2025) (lundiebrown2025cellfateacquisition pages 9-11, lundiebrown2025cellfateacquisition pages 11-12).
- Direct transcriptional targets and pathway positioning: ASCL1 directly activates neuroendocrine/neural effectors including INSM1, MYT1, and multiple neuroendocrine markers, and it transcriptionally upregulates Notch-modulatory ligands such as DLL1/DLL3. This places ASCL1 upstream of Notch repression in neuroendocrine lineages, where DLL3 acts as an inhibitory Notch ligand (https://doi.org/10.1172/jci175217, Jul 2024; https://doi.org/10.1158/2767-9764.crc-24-0501, Feb 2025) (ku2024notchsignalingsuppresses pages 1-2, lozada2025expressionpatternsof pages 1-2). Additional ASCL1 targets frequently cited in SCLC include CHGA, CALCB, and RET (OpenTargets summary of curated evidence) (OpenTargets Search: Small cell lung cancer,Neuroblastoma-ASCL1).
- Biological roles: In development, ASCL1 is a proneural factor required for neuronal differentiation and neuroendocrine lineage specification. In cancer, it is a lineage-defining oncoprotein that maintains neuroendocrine identity and survival programs, particularly in the ASCL1-dominant subtype of small cell lung cancer (SCLC-A) (https://doi.org/10.1097/cm9.0000000000002693) (guo2024molecularclassificationof pages 1-2).
Recent developments and latest research (prioritize 2023–2024)
- Post-translational and cell-cycle regulation (2024): In SCLC, ASCL1 protein abundance is dynamically regulated by the cell cycle. CDK2–CyclinA2 phosphorylates ASCL1, promoting proteasome-mediated degradation during mitosis via the E3 ligase HUWE1; interaction with the E-protein TCF3 protects ASCL1 from degradation, and chemotherapy decreases ASCL1 transcription while ASCL1 depletion sensitizes cells to chemotherapy (https://doi.org/10.1158/1541-7786.mcr-23-0405, Mar 2024) (liu2024distinctregulationof pages 1-2). Broader mechanistic syntheses similarly emphasize HUWE1-mediated ubiquitination and E-protein–dependent stabilization as central regulatory nodes (Molecules review, 2025) (huang2025molecularsubtypesand pages 6-7).
- Oncogenic lineage role and subtype prevalence (2024): Molecular classification work consolidates ASCL1 as the dominant lineage-defining TF in SCLC-A, with reported prevalence around 70–75% of tumors. This classification corresponds to distinct biology, microenvironment features, and therapeutic vulnerabilities (https://doi.org/10.1097/cm9.0000000000002693, Sep 2024) (guo2024molecularclassificationof pages 1-2). OpenTargets curation likewise highlights subtype-specific dependency on ASCL1 in SCLC models (OpenTargets Search: Small cell lung cancer,Neuroblastoma-ASCL1).
- ASCL1–Notch axis across neuroendocrine cancers (2024): In advanced prostate cancer, activation of Notch suppresses neuroendocrine differentiation; DLL3 is an inhibitory Notch ligand transcriptionally activated by ASCL1, reinforcing the conserved ASCL1–DLL3–Notch axis in neuroendocrine states (https://doi.org/10.1172/jci175217, Jul 2024) (ku2024notchsignalingsuppresses pages 1-2).
- Drug tolerance and plasticity (2024): In EGFR-mutant lung adenocarcinoma PDXs, osimertinib treatment can induce ASCL1 upregulation in residual disease, where ASCL1 drives an EMT-like program conferring drug tolerance in permissive cellular contexts. This connects ASCL1 to therapy-induced lineage plasticity beyond classical SCLC (https://doi.org/10.1158/0008-5472.can-23-0438, Feb 2024) (hu2024ascl1drivestolerance pages 1-3).
- Tumor evolution under therapy (2024): Longitudinal multi-region sequencing in SCLC reveals branched evolution and relapse from ancestral clones under therapy. While genomic states dominated the analysis, these data contextualize how lineage programs (including ASCL1-driven states) are embedded within evolving clonal architectures (https://doi.org/10.1038/s41586-024-07177-7, Mar 2024) (ku2024notchsignalingsuppresses pages 1-2).
- Multi-omics trajectories (2024): Recent multi-omics analyses of neuroendocrine trans-differentiation identify ASCL1 as a master regulator with bifurcating lineage endpoints and reciprocal relationships with other lineage TFs (e.g., ASCL2/POU2F3), consistent with ASCL1’s role in shaping neuroendocrine states (2024 study) (chen2024multiomicstranscriptionalprofiling pages 74-78).
Current applications and real-world implementations
- Subtype classification and biomarker use: ASCL1 immunohistochemistry/RNA profiling is used to classify SCLC into lineage subtypes; ASCL1-high (SCLC-A) tumors display neuroendocrine programs and distinct vulnerabilities. Estimates place SCLC-A at ~70–75% of SCLC, with NEUROD1, POU2F3, and immune-inflamed subtypes comprising the remainder (https://doi.org/10.1097/cm9.0000000000002693) (guo2024molecularclassificationof pages 1-2).
- DLL3-targeted therapies linked to ASCL1 programs: DLL3, commonly activated by ASCL1 and serving as a Notch inhibitor, is widely expressed in neuroendocrine malignancies. Tarlatamab, a DLL3×CD3 bispecific T-cell engager (BiTE), achieved objective responses around 40% in previously treated SCLC in phase II and received FDA approval in 2024 for chemotherapy-refractory extensive-stage SCLC, illustrating rapid clinical translation of ASCL1→DLL3 biology (Cancer Research Communications, 2025; Frontiers in Immunology, 2025; see also JCI 2024 for ASCL1→DLL3 regulation) (https://doi.org/10.1158/2767-9764.crc-24-0501; https://doi.org/10.3389/fimmu.2025.1592291; https://doi.org/10.1172/jci175217) (lozada2025expressionpatternsof pages 2-3, lozada2025expressionpatternsof pages 1-2, ji2025harnessingdeltalikeligand pages 1-2, ku2024notchsignalingsuppresses pages 1-2, ji2025harnessingdeltalikeligand pages 5-6).
- Broader modalities: DLL3-targeted strategies under investigation include next-generation bispecifics (e.g., HPN328), CAR T/NK constructs, radioimmunoconjugates, and photoimmunotherapy, with early clinical signals of activity and evolving safety profiles (https://doi.org/10.3389/fimmu.2025.1592291) (ji2025harnessingdeltalikeligand pages 5-6). Historical DLL3 ADCs (rovalpituzumab tesirine) showed response enrichment in DLL3-high tumors but were discontinued due to toxicity and inferior survival in later studies, informing current modality choices (https://doi.org/10.1158/2767-9764.crc-24-0501) (lozada2025expressionpatternsof pages 6-7).
Expert opinions and analysis from authoritative sources
- Nature/clinical oncology synthesis: A 2024 Nature Reviews Clinical Oncology perspective emphasizes the centrality of lineage-defining TFs (ASCL1, NEUROD1, POU2F3) in SCLC biology, the existence of plasticity between subtypes, and the therapeutic implications for patient stratification and resistance management (https://doi.org/10.1038/s41571-024-00914-x, Jul 2024) (huang2025molecularsubtypesand pages 6-7). The Nature 2024 tumor-evolution study further underscores the complexity of relapse and the need to integrate lineage programs with clonal dynamics to optimize therapy (https://doi.org/10.1038/s41586-024-07177-7, Mar 2024) (ku2024notchsignalingsuppresses pages 1-2).
- Mechanistic regulation consensus: Experimental work (MCR 2024) and synthesis (Open Biology 2025) converge on a model where ASCL1’s function is tuned by multi-site phosphorylation (CDK/ERK pathways), ubiquitin-mediated turnover (HUWE1), chromatin engagement that is stabilized by E-proteins (TCF3), and feedback with Notch signaling via DLL ligands (https://doi.org/10.1158/1541-7786.mcr-23-0405; https://doi.org/10.1098/rsob.250018) (liu2024distinctregulationof pages 1-2, lundiebrown2025cellfateacquisition pages 11-12).
Relevant statistics and recent quantitative data
- Prevalence of ASCL1-high SCLC: Approximately 70–75% of SCLC classified as SCLC-A/ASCL1-dominant, based on recent clinical-molecular reviews (Sep 2024) (https://doi.org/10.1097/cm9.0000000000002693) (guo2024molecularclassificationof pages 1-2). OpenTargets curation corroborates high frequency of ASCL1 dependency in SCLC models (OpenTargets Search: Small cell lung cancer,Neuroblastoma-ASCL1).
- DLL3 prevalence: DLL3 overexpression in neuroendocrine tumors is common (~70–80% in SCLC); high DLL3 correlates with aggressive histology and adverse outcomes in multiple NEN sites, supporting biomarker-driven selection (Cancer Research Communications 2025; Frontiers in Immunology 2025) (https://doi.org/10.1158/2767-9764.crc-24-0501; https://doi.org/10.3389/fimmu.2025.1592291) (lozada2025expressionpatternsof pages 1-2, lozada2025expressionpatternsof pages 2-3, ji2025harnessingdeltalikeligand pages 1-2).
- SCLC survival context: SCLC remains highly lethal with very low 5-year overall survival (often <7%), underscoring the need for subtype- and biomarker-driven therapeutics such as DLL3-directed agents (Frontiers in Immunology 2025) (https://doi.org/10.3389/fimmu.2025.1592291) (ji2025harnessingdeltalikeligand pages 5-6).
- Clinical activity of DLL3 BiTE: Tarlatamab has shown approximately 40% objective response rates in previously treated SCLC in phase II, forming the basis for regulatory approval and ongoing integration into practice (CRC 2025) (https://doi.org/10.1158/2767-9764.crc-24-0501) (lozada2025expressionpatternsof pages 2-3).
Mechanistic details: pathways, targets, and regulation
- Pathways and targets: ASCL1 directly activates neuroendocrine transcriptional modules (e.g., INSM1, MYT1) and induces DLL1/DLL3, which modulate Notch signaling to support neuroendocrine differentiation; ASCL1 also co-regulates programs with other TFs in pulmonary neuroendocrine cells and SCLC-A (e.g., NKX2-1, PROX1 reported in curated compendia) (JCI 2024; OpenTargets) (https://doi.org/10.1172/jci175217) (ku2024notchsignalingsuppresses pages 1-2, OpenTargets Search: Small cell lung cancer,Neuroblastoma-ASCL1).
- Post-translational control: CDK2–CyclinA2-mediated phosphorylation and HUWE1-dependent ubiquitination regulate ASCL1 turnover during mitosis; E-protein (TCF3) association protects ASCL1 from degradation and coordinates DNA binding. Chemotherapy downregulates ASCL1 transcription, and genetic depletion enhances chemosensitivity in SCLC models (MCR 2024) (https://doi.org/10.1158/1541-7786.mcr-23-0405) (liu2024distinctregulationof pages 1-2). Phosphorylation status modulates chromatin opening and reprogramming potency, linking ASCL1 function to kinase signaling (Open Biology 2025) (https://doi.org/10.1098/rsob.250018) (lundiebrown2025cellfateacquisition pages 11-12).
- Chromatin engagement: ASCL1 binds nucleosomal DNA and remodels chromatin to pioneer neuronal/neuroendocrine enhancers, with E-proteins enhancing nucleosome affinity and occupancy at E-box-rich regions (Open Biology 2025) (https://doi.org/10.1098/rsob.250018) (lundiebrown2025cellfateacquisition pages 9-11, lundiebrown2025cellfateacquisition pages 11-12).
Clinical and translational implications
- Diagnostic and stratification use: ASCL1 expression supports SCLC molecular subtyping (SCLC-A), which correlates with neuroendocrine marker expression (INSM1, SYP, CHGA) and potential therapeutic vulnerabilities. Subtype-aware management is increasingly incorporated in trials and translational pipelines (https://doi.org/10.1097/cm9.0000000000002693) (guo2024molecularclassificationof pages 1-2).
- DLL3 as a therapeutic conduit of ASCL1 programs: ASCL1-driven DLL3 expression provides a tumor-restricted target across neuroendocrine malignancies. Tarlatamab’s 2024 approval in refractory SCLC and observed ~40% response rate in trials exemplify biomarker-guided immunotherapy based on ASCL1 biology. Alternative platforms (HPN328 TriTAC, CAR T/NK, RIT) are being refined to optimize efficacy/safety and address resistance mechanisms such as DLL3 loss (https://doi.org/10.1158/2767-9764.crc-24-0501; https://doi.org/10.3389/fimmu.2025.1592291) (lozada2025expressionpatternsof pages 2-3, lozada2025expressionpatternsof pages 6-7, ji2025harnessingdeltalikeligand pages 5-6).
- Therapy resistance/plasticity: ASCL1-driven gene programs can contribute to drug tolerance and lineage plasticity under targeted therapy pressure (osimertinib in EGFR-mutant tumors), suggesting that intercepting ASCL1 function or its downstream programs may mitigate residual disease (https://doi.org/10.1158/0008-5472.can-23-0438) (hu2024ascl1drivestolerance pages 1-3).
Structured summary
| Aspect | Key points (1–2 sentences) | Recent sources (Year; journal; DOI/URL) |
|---|---|---|
| Identity / domain & localization | Human ASCL1 (UniProt P50553) is a nuclear basic helix–loop–helix (bHLH) proneural transcription factor with canonical bHLH/MASH1 family features and nuclear localization. | Liu 2024; Molecular Cancer Research; https://doi.org/10.1158/1541-7786.mcr-23-0405 (Mar 2024) (liu2024distinctregulationof pages 1-2), Guo 2024; Chinese Medical Journal; https://doi.org/10.1097/cm9.0000000000002693 (Sep 2024) (guo2024molecularclassificationof pages 1-2), Open Targets summary (OpenTargets Search: Small cell lung cancer,Neuroblastoma-ASCL1) |
| Molecular function & pioneer activity | ASCL1 functions as a proneural bHLH transcription factor and exhibits pioneer-like chromatin engagement: binds E-box motifs, accesses nucleosomal DNA, and can open chromatin to activate neuronal programs. | Lundie-Brown 2025; Open Biology; https://doi.org/10.1098/rsob.250018 (lundiebrown2025cellfateacquisition pages 9-11, lundiebrown2025cellfateacquisition pages 11-12) |
| Direct targets & pathways (INSM1, MYT1, DLL1/DLL3; Notch axis) | ASCL1 activates neuroendocrine/neural programs including INSM1 and MYT1 and drives expression of Notch-modulatory ligands (DLL1, DLL3), placing ASCL1 upstream of Notch repression in NE lineages. | Ku 2024; J Clin Invest; https://doi.org/10.1172/jci175217 (Jul 2024) (ku2024notchsignalingsuppresses pages 1-2), Chen 2024; multi-omics SCLC study (chen2024multiomicstranscriptionalprofiling pages 74-78), Open Targets summary (OpenTargets Search: Small cell lung cancer,Neuroblastoma-ASCL1) |
| Regulation (cell cycle, phosphorylation, ubiquitination, E-proteins) | ASCL1 is cell-cycle regulated: CDK2–CyclinA2 phosphorylation and HUWE1-mediated ubiquitination control mitotic degradation; heterodimerization with E-proteins (e.g., TCF3) stabilizes DNA-bound ASCL1. | Liu 2024; Molecular Cancer Research; https://doi.org/10.1158/1541-7786.mcr-23-0405 (liu2024distinctregulationof pages 1-2), Lundie-Brown 2025; Open Biology (lundiebrown2025cellfateacquisition pages 11-12) |
| Role in SCLC (subtypes, prevalence, dependency) | ASCL1 defines the SCLC-A (neuroendocrine) lineage and is required for tumor initiation/survival in ASCL1-high tumors; reported prevalence for ASCL1-dominant SCLC is ~70–75%. | Guo 2024; Chinese Medical Journal; https://doi.org/10.1097/cm9.0000000000002693 (guo2024molecularclassificationof pages 1-2), Liu 2024; MCR (liu2024distinctregulationof pages 1-2), Open Targets summary (OpenTargets Search: Small cell lung cancer,Neuroblastoma-ASCL1) |
| Plasticity / therapy resistance (EGFR-mutant tolerance) | ASCL1 upregulation can drive drug-tolerant states and lineage plasticity (e.g., EMT-like programs) and has been implicated in tolerance to EGFR TKI osimertinib in permissive contexts. | Hu 2024; Cancer Research; https://doi.org/10.1158/0008-5472.can-23-0438 (Feb 2024) (hu2024ascl1drivestolerance pages 1-3), Chen 2024 multi-omics (chen2024multiomicstranscriptionalprofiling pages 74-78) |
| Clinical / translational applications (biomarker, DLL3 targeting, tarlatamab) | ASCL1 stratifies SCLC subtypes and correlates with DLL3 expression; DLL3-directed therapies (BiTEs/CARs) advanced clinically — tarlatamab (DLL3×CD3 BiTE) reported strong activity in refractory SCLC (~ORR ≈40% in phase II) and regulatory progress in 2024. | Lozada 2025; Cancer Res Commun; https://doi.org/10.1158/2767-9764.crc-24-0501 (Feb 2025) (lozada2025expressionpatternsof pages 2-3, lozada2025expressionpatternsof pages 1-2), Ji 2025; Frontiers Immunology; https://doi.org/10.3389/fimmu.2025.1592291 (May 2025) (ji2025harnessingdeltalikeligand pages 5-6), Open Targets summary (OpenTargets Search: Small cell lung cancer,Neuroblastoma-ASCL1) |
| Quantitative statistics | Reported metrics: DLL3 expression in NE tumors ~70–80%; SCLC-A accounts for ~70–75% of SCLC cases; SCLC 5‑year overall survival remains very low (<~7% reported in recent reviews). | DLL3 prevalence & DLL3–clinical data: Lozada 2025 (lozada2025expressionpatternsof pages 1-2, lozada2025expressionpatternsof pages 2-3), SCLC-A prevalence: Liu 2024 (liu2024distinctregulationof pages 1-2), Guo 2024 (guo2024molecularclassificationof pages 1-2); SCLC survival context: Ji 2025 / reviews (ji2025harnessingdeltalikeligand pages 5-6) |
Table: Compact 2023–2024–focused evidence summary for human ASCL1 (UniProt P50553) summarizing identity, mechanisms, pathways, regulation, role in SCLC, plasticity, clinical applications and key quantitative stats with primary recent sources cited for each item.
Conclusion
Human ASCL1 (UniProt P50553) is a nuclear bHLH transcription factor with pioneer-like chromatin activity that drives neuronal and neuroendocrine programs. It directly upregulates neuroendocrine effectors (e.g., INSM1, MYT1) and Notch-modulatory ligands (DLL1/DLL3), establishing a regulatory axis in which ASCL1 promotes neuroendocrine differentiation while repressing Notch signaling via DLL3. In cancer, ASCL1 defines the dominant SCLC-A lineage (~70–75%) and is essential for tumor maintenance in ASCL1-high models. Recent studies (2023–2024) clarify its cell-cycle/post-translational control (CDK2–CyclinA2 phosphorylation; HUWE1 ubiquitination; TCF3 stabilization), its role in therapy-induced plasticity, and its translational linkage to DLL3-targeted immunotherapies, including the 2024 FDA approval of tarlatamab for refractory SCLC. These advances underscore ASCL1’s centrality in neuroendocrine biology and its value as a biomarker and mechanistic anchor for emerging precision therapies (liu2024distinctregulationof pages 1-2, lundiebrown2025cellfateacquisition pages 9-11, huang2025molecularsubtypesand pages 6-7, chen2024multiomicstranscriptionalprofiling pages 74-78, hu2024ascl1drivestolerance pages 1-3, lundiebrown2025cellfateacquisition pages 11-12, guo2024molecularclassificationof pages 1-2, lozada2025expressionpatternsof pages 2-3, lozada2025expressionpatternsof pages 6-7, lozada2025expressionpatternsof pages 1-2, ji2025harnessingdeltalikeligand pages 1-2, ku2024notchsignalingsuppresses pages 1-2, ji2025harnessingdeltalikeligand pages 5-6).
References
(liu2024distinctregulationof pages 1-2): Yuning Liu, Qingzhe Wu, Bin Jiang, Tingting Hou, Chuanqiang Wu, Ming Wu, and Hai Song. Distinct regulation of ascl1 by the cell cycle and chemotherapy in small cell lung cancer. Molecular Cancer Research, 22:613-624, Mar 2024. URL: https://doi.org/10.1158/1541-7786.mcr-23-0405, doi:10.1158/1541-7786.mcr-23-0405. This article has 7 citations and is from a peer-reviewed journal.
(guo2024molecularclassificationof pages 1-2): Hanfei Guo, Wenqian Li, Ye Guo, Naifei Chen, and Jiuwei Cui. Molecular classification of small cell lung cancer subtypes: characteristics, prognostic factors, and clinical translation. Chinese Medical Journal, 137:130-139, Sep 2024. URL: https://doi.org/10.1097/cm9.0000000000002693, doi:10.1097/cm9.0000000000002693. This article has 5 citations and is from a peer-reviewed journal.
(lundiebrown2025cellfateacquisition pages 9-11): Jethro Lundie-Brown, Francesca Puletti, Anna Philpott, and Roberta Azzarelli. Cell fate acquisition and reprogramming by the proneural transcription factor ascl1. Open Biology, Jun 2025. URL: https://doi.org/10.1098/rsob.250018, doi:10.1098/rsob.250018. This article has 3 citations and is from a peer-reviewed journal.
(lundiebrown2025cellfateacquisition pages 11-12): Jethro Lundie-Brown, Francesca Puletti, Anna Philpott, and Roberta Azzarelli. Cell fate acquisition and reprogramming by the proneural transcription factor ascl1. Open Biology, Jun 2025. URL: https://doi.org/10.1098/rsob.250018, doi:10.1098/rsob.250018. This article has 3 citations and is from a peer-reviewed journal.
(ku2024notchsignalingsuppresses pages 1-2): Sheng-Yu Ku, Yanqing Wang, Maria Mica Garcia, Yasutaka Yamada, Kei Mizuno, Mark D. Long, Spencer Rosario, Meenalakshmi Chinnam, Majd Al Assaad, Loredana Puca, Min Jin Kim, Martin K. Bakht, Varadha Balaji Venkadakrishnan, Brian D. Robinson, Andrés M. Acosta, Kristine M. Wadosky, Juan Miguel Mosquera, David W. Goodrich, and Himisha Beltran. Notch signaling suppresses neuroendocrine differentiation and alters the immune microenvironment in advanced prostate cancer. The Journal of Clinical Investigation, Jul 2024. URL: https://doi.org/10.1172/jci175217, doi:10.1172/jci175217. This article has 29 citations.
(lozada2025expressionpatternsof pages 1-2): John R. Lozada, Andrew Elliott, Mark G. Evans, James Wacker, Kathleen M. Storey, Emily A. Egusa, Nicholas A. Zorko, Akhilesh Kumar, Anthony Crymes, Elisabeth I. Heath, Benedito A. Carneiro, Heloisa P. Soares, Frank Cichocki, Jeffrey S. Miller, Emil Lou, Himisha Beltran, Emmanuel S. Antonarakis, Charles J. Ryan, and Justin H. Hwang. Expression patterns of dll3 across neuroendocrine and non-neuroendocrine neoplasms reveal broad opportunities for therapeutic targeting. Cancer Research Communications, 5:318-326, Feb 2025. URL: https://doi.org/10.1158/2767-9764.crc-24-0501, doi:10.1158/2767-9764.crc-24-0501. This article has 8 citations and is from a peer-reviewed journal.
(OpenTargets Search: Small cell lung cancer,Neuroblastoma-ASCL1): Open Targets Query (Small cell lung cancer,Neuroblastoma-ASCL1, 4 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.
(huang2025molecularsubtypesand pages 6-7): Daoyuan Huang, Jingchao Wang, Li Chen, Weiwei Jiang, Hiroyuki Inuzuka, David K. Simon, and Wenyi Wei. Molecular subtypes and targeted therapeutic strategies in small cell lung cancer: advances, challenges, and future perspectives. Molecules, 30:1731, Apr 2025. URL: https://doi.org/10.3390/molecules30081731, doi:10.3390/molecules30081731. This article has 12 citations and is from a poor quality or predatory journal.
(hu2024ascl1drivestolerance pages 1-3): Bomiao Hu, Marc Wiesehöfer, Fernando J. de Miguel, Zongzhi Liu, Lok-Hei Chan, Jungmin Choi, Mary Ann Melnick, Anna Arnal Estape, Zenta Walther, Dejian Zhao, Francesc Lopez-Giraldez, Anna Wurtz, Guoping Cai, Rong Fan, Scott Gettinger, Andrew Xiao, Qin Yan, Robert Homer, Don X. Nguyen, and Katerina Politi. Ascl1 drives tolerance to osimertinib in egfr mutant lung cancer in permissive cellular contexts. Cancer research, 84:1303-1319, Feb 2024. URL: https://doi.org/10.1158/0008-5472.can-23-0438, doi:10.1158/0008-5472.can-23-0438. This article has 25 citations and is from a highest quality peer-reviewed journal.
(chen2024multiomicstranscriptionalprofiling pages 74-78): CC Chen. Multi-omics transcriptional profiling of neuroendocrine trans-differentiation in small cell carcinoma. Unknown journal, 2024.
(lozada2025expressionpatternsof pages 2-3): John R. Lozada, Andrew Elliott, Mark G. Evans, James Wacker, Kathleen M. Storey, Emily A. Egusa, Nicholas A. Zorko, Akhilesh Kumar, Anthony Crymes, Elisabeth I. Heath, Benedito A. Carneiro, Heloisa P. Soares, Frank Cichocki, Jeffrey S. Miller, Emil Lou, Himisha Beltran, Emmanuel S. Antonarakis, Charles J. Ryan, and Justin H. Hwang. Expression patterns of dll3 across neuroendocrine and non-neuroendocrine neoplasms reveal broad opportunities for therapeutic targeting. Cancer Research Communications, 5:318-326, Feb 2025. URL: https://doi.org/10.1158/2767-9764.crc-24-0501, doi:10.1158/2767-9764.crc-24-0501. This article has 8 citations and is from a peer-reviewed journal.
(ji2025harnessingdeltalikeligand pages 1-2): Kangkang Ji, Lin Guo, Dianbao Zuo, Mingqian Feng, Xin Chen, Zhenggang Zhao, Jing Tang, and Guoping Chen. Harnessing delta-like ligand 3: bridging biomarker discovery to next-generation immunotherapies in refractory small cell lung cancer. Frontiers in Immunology, May 2025. URL: https://doi.org/10.3389/fimmu.2025.1592291, doi:10.3389/fimmu.2025.1592291. This article has 2 citations and is from a peer-reviewed journal.
(ji2025harnessingdeltalikeligand pages 5-6): Kangkang Ji, Lin Guo, Dianbao Zuo, Mingqian Feng, Xin Chen, Zhenggang Zhao, Jing Tang, and Guoping Chen. Harnessing delta-like ligand 3: bridging biomarker discovery to next-generation immunotherapies in refractory small cell lung cancer. Frontiers in Immunology, May 2025. URL: https://doi.org/10.3389/fimmu.2025.1592291, doi:10.3389/fimmu.2025.1592291. This article has 2 citations and is from a peer-reviewed journal.
(lozada2025expressionpatternsof pages 6-7): John R. Lozada, Andrew Elliott, Mark G. Evans, James Wacker, Kathleen M. Storey, Emily A. Egusa, Nicholas A. Zorko, Akhilesh Kumar, Anthony Crymes, Elisabeth I. Heath, Benedito A. Carneiro, Heloisa P. Soares, Frank Cichocki, Jeffrey S. Miller, Emil Lou, Himisha Beltran, Emmanuel S. Antonarakis, Charles J. Ryan, and Justin H. Hwang. Expression patterns of dll3 across neuroendocrine and non-neuroendocrine neoplasms reveal broad opportunities for therapeutic targeting. Cancer Research Communications, 5:318-326, Feb 2025. URL: https://doi.org/10.1158/2767-9764.crc-24-0501, doi:10.1158/2767-9764.crc-24-0501. This article has 8 citations and is from a peer-reviewed journal.
id: P50553
gene_symbol: ASCL1
product_type: PROTEIN
status: COMPLETE
taxon:
id: NCBITaxon:9606
label: Homo sapiens
description: >-
ASCL1 (Achaete-scute homolog 1, also known as MASH1/hASH1) is a proneural basic
helix-loop-helix (bHLH)
transcription factor that functions as both a classical transcriptional activator
and a pioneer factor
capable of accessing closed chromatin. It binds E-box motifs (CANNTG, particularly
CACCTG) as a heterodimer
with E-proteins (TCF3/E12/E47, TCF4) to activate neuronal and neuroendocrine gene
programs. ASCL1 plays
essential roles in neuronal differentiation, neuronal fate commitment, and neuroendocrine
cell development.
It is a master regulator of the SCLC-A (neuroendocrine) subtype of small cell lung
cancer and directly
activates targets including INSM1, MYT1, DLL1, and DLL3 (Notch pathway modulators).
ASCL1 protein
stability is regulated by CDK2-CyclinA2 phosphorylation, HUWE1-mediated ubiquitination,
and protection
via E-protein heterodimerization.
existing_annotations:
- term:
id: GO:0030182
label: neuron differentiation
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
Neuron differentiation is a core function of ASCL1. The IBA annotation is
well-supported by phylogenetic
analysis and extensive experimental evidence. ASCL1 (MASH1) is essential for
proper development of
olfactory and autonomic neurons and for neuronal differentiation in the CNS
and PNS (PMID:10903890).
ASCL1 overexpression increases neurogenesis in human neural progenitor cells
(PMID:19008346).
action: ACCEPT
reason: >-
This is a core function of ASCL1. The protein is classified as a proneural
bHLH transcription factor
whose primary role is driving neuronal differentiation. Multiple experimental
studies confirm this
function, and the IBA phylogenetic inference is consistent with the extensive
literature.
supported_by:
- reference_id: PMID:10903890
supporting_text: "The basic helix-loop-helix (bHLH) transcription factor
mammalian achaete-scute homolog-1 (MASH-1 in mouse and HASH-1 in human)
is essential for proper development of olfactory and most peripheral autonomic
neurons, and for the formation of distinct neuronal circuits within the
central nervous system."
- reference_id: PMID:19008346
supporting_text: "By overexpressing one of these, the transcription factor
ASCL1, we were able to regain neurogenesis from hNPC(VM) cultures"
- reference_id: file:human/ASCL1/ASCL1-deep-research-cyberian.md
supporting_text: 'model: deep-research'
- term:
id: GO:0007423
label: sensory organ development
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
ASCL1 is essential for development of olfactory neurons, which are part of
the olfactory sensory
organ system. The IBA annotation captures the role in sensory (specifically
olfactory) development.
action: KEEP_AS_NON_CORE
reason: >-
While ASCL1 is essential for olfactory neuron development (a sensory system),
this is a more peripheral
consequence of its neuronal differentiation function rather than a core molecular
function. The term
is appropriate but represents a downstream developmental phenotype.
supported_by:
- reference_id: PMID:10903890
supporting_text: "The basic helix-loop-helix (bHLH) transcription factor
mammalian achaete-scute homolog-1 (MASH-1 in mouse and HASH-1 in human)
is essential for proper development of olfactory and most peripheral autonomic
neurons, and for the formation of distinct neuronal circuits within the
central nervous system."
- term:
id: GO:0045944
label: positive regulation of transcription by RNA polymerase II
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
ASCL1 is a transcriptional activator that transactivates E-box containing
reporter constructs
(PMID:10903890). It drives transcription of neuronal and neuroendocrine gene
programs.
action: ACCEPT
reason: >-
This is a core function. ASCL1 functions as a transcriptional activator, directly
demonstrated
by reporter assays showing transactivation of E-box containing constructs
when complexed with
E-proteins like E2-2/TCF4.
supported_by:
- reference_id: PMID:10903890
supporting_text: "The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro,
and transactivates an E-box containing reporter construct in vivo."
- term:
id: GO:0000977
label: RNA polymerase II transcription regulatory region sequence-specific
DNA binding
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
ASCL1 binds sequence-specifically to E-box elements (CANNTG, particularly
CACCTG) in promoter
and enhancer regions. This DNA binding is essential for its transcription
factor activity.
action: ACCEPT
reason: >-
This is a core molecular function. Multiple studies demonstrate E-box binding
by gel shift assays
and functional studies. ASCL1 binds as a heterodimer with E-proteins to specific
DNA sequences.
supported_by:
- reference_id: PMID:10903890
supporting_text: "The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro"
- reference_id: PMID:11736660
supporting_text: "Binding of hASH-1 to the E-box cluster was confirmed by
gel mobility-shift assay."
- term:
id: GO:0000981
label: DNA-binding transcription factor activity, RNA polymerase
II-specific
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
ASCL1 is a DNA-binding transcription factor that regulates RNA polymerase
II-dependent transcription.
This is the fundamental molecular function of ASCL1 as a bHLH transcription
factor.
action: ACCEPT
reason: >-
This is the core molecular function of ASCL1. It binds DNA via its bHLH domain
as a heterodimer
with E-proteins and regulates transcription of target genes. IDA evidence
also supports this
(PMID:10903890).
supported_by:
- reference_id: PMID:10903890
supporting_text: "The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro,
and transactivates an E-box containing reporter construct in vivo."
- term:
id: GO:0090575
label: RNA polymerase II transcription regulator complex
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
ASCL1 functions as part of a transcriptional regulatory complex, forming heterodimers
with E-proteins
(TCF3, TCF4) and interacting with chromatin remodeling complexes (mSWI/SNF
via ARID1A, SMARCC1).
action: ACCEPT
reason: >-
ASCL1 functions in transcription regulator complexes. It heterodimerizes with
E-proteins for DNA
binding and interacts with mSWI/SNF chromatin remodeling complexes (PMID:36931659).
UniProt records
interactions with TCF3, TCF4, ARID1A, and SMARCC1.
supported_by:
- reference_id: PMID:10903890
supporting_text: "E2-2 forms a functional complex with HASH-1"
- reference_id: PMID:36931659
supporting_text: "ASCL1 interacts with BAF SWI/SNF chromatin remodeling
complexes"
- term:
id: GO:0050767
label: regulation of neurogenesis
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
ASCL1 is a master regulator of neurogenesis. Overexpression increases neurogenesis
(PMID:19008346),
and it is required for neuronal differentiation from progenitor cells.
action: ACCEPT
reason: >-
This is a core biological process for ASCL1. The IBA annotation is well-supported
by extensive
experimental evidence showing ASCL1 positively regulates neurogenesis.
supported_by:
- reference_id: PMID:19008346
supporting_text: "Regionally specified human neural progenitor cells derived
from the mesencephalon and forebrain undergo increased neurogenesis following
overexpression of ASCL1."
- term:
id: GO:0003677
label: DNA binding
evidence_type: IEA
original_reference_id: GO_REF:0000043
review:
summary: >-
ASCL1 binds DNA via its bHLH domain. This IEA annotation based on UniProt
keywords is correct
but less specific than other available annotations (E-box binding, sequence-specific
DNA binding).
action: MARK_AS_OVER_ANNOTATED
reason: >-
While correct, this term is too general. More specific terms like E-box binding
(GO:0070888) and
sequence-specific double-stranded DNA binding (GO:1990837) are available and
already annotated
with experimental evidence.
proposed_replacement_terms:
- id: GO:0070888
label: E-box binding
- id: GO:1990837
label: sequence-specific double-stranded DNA binding
- term:
id: GO:0003700
label: DNA-binding transcription factor activity
evidence_type: IEA
original_reference_id: GO_REF:0000120
review:
summary: >-
ASCL1 is a DNA-binding transcription factor. This IEA annotation is correct
and supported by
IDA evidence from PMID:10903890.
action: ACCEPT
reason: >-
This is a core molecular function. The IEA annotation is correct and redundant
with the IDA
annotation from PMID:10903890, which provides experimental support.
supported_by:
- reference_id: PMID:10903890
supporting_text: "The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro,
and transactivates an E-box containing reporter construct in vivo."
- term:
id: GO:0005634
label: nucleus
evidence_type: IEA
original_reference_id: GO_REF:0000120
review:
summary: >-
ASCL1 localizes to the nucleus where it functions as a transcription factor.
This is supported
by multiple IDA annotations (PMID:12858003, PMID:17507989, PMID:18311112).
action: ACCEPT
reason: >-
Nuclear localization is essential for ASCL1 function as a transcription factor.
The IEA annotation
is correct and supported by multiple IDA annotations from immunohistochemistry
studies.
supported_by:
- reference_id: PMID:12858003
supporting_text: "Immunohistochemically, pulmonary neuroendocrine cells
(PNECs) are positive for Mash1"
- term:
id: GO:0006357
label: regulation of transcription by RNA polymerase II
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: >-
ASCL1 regulates transcription by RNA polymerase II, functioning as both an
activator and repressor
depending on context and target gene.
action: ACCEPT
reason: >-
This is a core function of ASCL1. It regulates transcription both positively
(neuronal genes) and
negatively (e.g., PACE4 gene). The IEA annotation is appropriate.
supported_by:
- reference_id: PMID:10903890
supporting_text: "transactivates an E-box containing reporter construct
in vivo"
- reference_id: PMID:11736660
supporting_text: "The overexpression of hASH-1 or MASH-1 causes a marked
decrease in endogenous PACE4 gene expression"
- term:
id: GO:0007399
label: nervous system development
evidence_type: IEA
original_reference_id: GO_REF:0000120
review:
summary: >-
ASCL1 is essential for nervous system development, particularly neuronal differentiation
in CNS and PNS.
action: ACCEPT
reason: >-
This is a core biological process. ASCL1 is essential for CNS and PNS neuron
development.
More specific child terms are also annotated, but this broader term is appropriate
as a summary.
supported_by:
- reference_id: PMID:10903890
supporting_text: "essential for proper development of olfactory and most
peripheral autonomic neurons, and for the formation of distinct neuronal
circuits within the central nervous system"
- term:
id: GO:0030154
label: cell differentiation
evidence_type: IEA
original_reference_id: GO_REF:0000043
review:
summary: >-
ASCL1 drives cell differentiation, specifically neuronal and neuroendocrine
differentiation.
action: MARK_AS_OVER_ANNOTATED
reason: >-
While correct, this term is too general. More specific terms like neuron differentiation
(GO:0030182)
and neuroendocrine cell differentiation are more appropriate and already annotated.
proposed_replacement_terms:
- id: GO:0030182
label: neuron differentiation
- term:
id: GO:0046983
label: protein dimerization activity
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: >-
ASCL1 forms heterodimers with E-proteins (TCF3, TCF4) via its HLH domain.
This dimerization is
essential for DNA binding and transcriptional activity.
action: ACCEPT
reason: >-
Dimerization is essential for ASCL1 function. It heterodimerizes with E-proteins
to bind DNA.
UniProt documents interactions with TCF3 and TCF4 with multiple experiments.
supported_by:
- reference_id: PMID:10903890
supporting_text: "E2-2 interacts with HASH-1 in both yeast and mammalian
cells. The HASH-1/E2-2 complex binds an E-box"
- term:
id: GO:0070888
label: E-box binding
evidence_type: IEA
original_reference_id: GO_REF:0000117
review:
summary: >-
ASCL1 binds E-box motifs (CANNTG, specifically CACCTG). This is demonstrated
by gel shift assays
and is essential for its transcription factor activity.
action: ACCEPT
reason: >-
E-box binding is a core molecular function of ASCL1. This IEA annotation is
correct and supported
by IDA annotations from PMID:10903890 and PMID:11736660.
supported_by:
- reference_id: PMID:10903890
supporting_text: "The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro"
- reference_id: PMID:11736660
supporting_text: "Binding of hASH-1 to the E-box cluster was confirmed by
gel mobility-shift assay"
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:10903890
review:
summary: >-
This annotation captures protein-protein interaction with E2-2/TCF4, identified
by yeast two-hybrid.
However, a more specific term (bHLH transcription factor binding) is available
and annotated.
action: REMOVE
reason: >-
The generic "protein binding" term is uninformative. The specific interaction
with E2-2 is better
captured by GO:0043425 (bHLH transcription factor binding) which is also annotated
from this reference.
proposed_replacement_terms:
- id: GO:0043425
label: bHLH transcription factor binding
supported_by:
- reference_id: PMID:10903890
supporting_text: HASH-1 and E2-2 are expressed in human neuroblastoma
cells and form a functional complex.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:32296183
review:
summary: >-
This annotation is from the HuRI high-throughput protein interactome study.
While the interactions
are likely valid, "protein binding" is uninformative without specifying the
binding partner.
action: REMOVE
reason: >-
Generic "protein binding" annotations from high-throughput studies provide
limited functional
insight. The term is too broad to be useful for understanding ASCL1 function.
supported_by:
- reference_id: PMID:32296183
supporting_text: Apr 8. A reference map of the human binary protein
interactome.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:33961781
review:
summary: >-
This annotation is from the BioPlex proteome-scale network study. While interactions
are documented,
the generic term provides no specific functional information.
action: REMOVE
reason: >-
Generic "protein binding" from high-throughput AP-MS studies is uninformative.
More specific
interaction terms should be used where the functional relevance is understood.
supported_by:
- reference_id: PMID:33961781
supporting_text: 2021 May 6. Dual proteome-scale networks reveal
cell-specific remodeling of the human interactome.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:36931659
review:
summary: >-
This study demonstrates ASCL1 interaction with mSWI/SNF chromatin remodeling
complexes (ARID1A,
SMARCC1). The specific functional context (chromatin remodeling cooperation)
is known.
action: MODIFY
reason: >-
The interaction with mSWI/SNF components is functionally relevant (pioneer
factor activity with
chromatin remodelers). A more specific term capturing the chromatin remodeling
complex interaction
would be more informative.
proposed_replacement_terms:
- id: GO:0140297
label: DNA-binding transcription factor binding
additional_reference_ids:
- PMID:36931659
supported_by:
- reference_id: PMID:36931659
supporting_text: "ASCL1 interacts with BAF SWI/SNF chromatin remodeling
complexes, primarily at targets where it acts as a nonpioneer factor"
- term:
id: GO:0003358
label: noradrenergic neuron development
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
ASCL1 is required for noradrenergic neuron development, as demonstrated by
mutation studies in
congenital central hypoventilation syndrome patients (PMID:14532329).
action: ACCEPT
reason: >-
This is a core biological process. HASH-1 mutations impair noradrenergic neuronal
development
in an in vitro model system, demonstrating the requirement for ASCL1 in this
process.
supported_by:
- reference_id: PMID:14532329
supporting_text: "All HASH-1 mutant alleles impaired noradrenergic neuronal
development, when overexpressed from adenoviral constructs."
- term:
id: GO:0003682
label: chromatin binding
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
ASCL1 exhibits pioneer factor activity, binding nucleosomal DNA and remodeling
chromatin at
neuronal enhancers. This is demonstrated by PMID:36931659.
action: ACCEPT
reason: >-
Chromatin binding is a core function of ASCL1 as a pioneer transcription factor.
It binds
nucleosomal DNA and cooperates with mSWI/SNF to remodel chromatin.
supported_by:
- reference_id: PMID:36931659
supporting_text: "Pioneer transcription factors are thought to play pivotal
roles in developmental processes by binding nucleosomal DNA to activate
gene expression"
- term:
id: GO:0003690
label: double-stranded DNA binding
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
ASCL1 binds double-stranded DNA at E-box motifs. This is demonstrated by gel
shift assays and
functional studies.
action: ACCEPT
reason: >-
This is a valid molecular function. ASCL1 binds dsDNA as a heterodimer with
E-proteins. More
specific IDA annotations exist (sequence-specific double-stranded DNA binding).
supported_by:
- reference_id: PMID:11736660
supporting_text: "Binding of hASH-1 to the E-box cluster was confirmed by
gel mobility-shift assay"
- term:
id: GO:0007507
label: heart development
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
This annotation is transferred from mouse/rat orthologs via Ensembl Compara.
While ASCL1 may
have some role in cardiac development (possibly via autonomic innervation),
this is not a
well-characterized primary function of human ASCL1.
action: KEEP_AS_NON_CORE
reason: >-
Heart development is not a primary function of ASCL1. Any role is likely secondary
to autonomic
nervous system development. The annotation is not wrong but represents a peripheral/indirect
function.
- term:
id: GO:0021879
label: forebrain neuron differentiation
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
ASCL1 is expressed in forebrain and drives neuron differentiation there, including
GABAergic
interneuron differentiation (PMID:12050665).
action: ACCEPT
reason: >-
This is a specific manifestation of ASCL1's neuronal differentiation function
in the forebrain.
Supported by evidence showing ASCL1/Mash1 expression in cortical progenitors.
supported_by:
- reference_id: PMID:12050665
supporting_text: "One lineage expresses Dlx1/2 and Mash1 transcription factors,
represents 65% of neocortical GABAergic neurons in humans, and originates
from Mash1-expressing progenitors of the neocortical ventricular and subventricular
zone of the dorsal forebrain."
- term:
id: GO:0030182
label: neuron differentiation
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
Duplicate annotation of neuron differentiation via Ensembl Compara transfer.
The IBA annotation
already captures this function with phylogenetic support.
action: ACCEPT
reason: >-
This is a core function. Duplicate with IBA annotation but both are valid.
The multiple evidence
codes reinforce the importance of this function.
supported_by:
- reference_id: PMID:10903890
supporting_text: "essential for proper development of olfactory and most
peripheral autonomic neurons"
- term:
id: GO:0032526
label: response to retinoic acid
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
ASCL1 expression is regulated in response to retinoic acid treatment. In SH-SY5Y
neuroblastoma
cells, ASCL1 expression is reduced after RA treatment as cells differentiate
(PMID:12000752).
action: KEEP_AS_NON_CORE
reason: >-
ASCL1 responds to retinoic acid (expression is downregulated during RA-induced
differentiation),
but this is a regulatory response rather than a core function. IEP evidence
exists (PMID:12000752).
supported_by:
- reference_id: PMID:12000752
supporting_text: "expression of neuroblast-specific ASCL1 (HASH-1) gene
was promptly reduced after RA treatment"
- term:
id: GO:0042802
label: identical protein binding
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
ASCL1 may form homodimers, though heterodimerization with E-proteins is the
functionally
characterized interaction mode for DNA binding.
action: UNDECIDED
reason: >-
While ASCL1 may homodimerize, the functionally important interaction is heterodimerization
with E-proteins. The evidence for homodimerization being functionally relevant
is limited.
- term:
id: GO:0043025
label: neuronal cell body
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
ASCL1 is expressed in neuronal cell bodies during development. As a transcription
factor,
it is primarily nuclear within these cells.
action: KEEP_AS_NON_CORE
reason: >-
The cellular component annotation is technically correct but less informative
than "nucleus."
ASCL1 is found in neuronal progenitors and differentiating neurons, localized
to the nucleus.
- term:
id: GO:0043565
label: sequence-specific DNA binding
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
ASCL1 binds DNA in a sequence-specific manner, recognizing E-box motifs. This
is well-supported
by experimental evidence.
action: ACCEPT
reason: >-
Sequence-specific DNA binding is a core molecular function. IDA evidence exists
for the more
specific term (sequence-specific double-stranded DNA binding) from PMID:28473536.
supported_by:
- reference_id: PMID:10903890
supporting_text: "The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro"
- term:
id: GO:0045665
label: negative regulation of neuron differentiation
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
This annotation appears contradictory since ASCL1 is primarily a positive
regulator of neuron
differentiation. The IDA annotation from PMID:12000752 appears to be an error
in interpretation.
action: REMOVE
reason: >-
ASCL1 is primarily a positive regulator of neuronal differentiation. The cited
evidence
(PMID:12000752) shows ASCL1 is downregulated during differentiation, which
is different from
ASCL1 negatively regulating differentiation. This annotation appears to be
an error.
- term:
id: GO:0045666
label: positive regulation of neuron differentiation
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
ASCL1 positively regulates neuron differentiation. This is the core function
of ASCL1 as a
proneural transcription factor.
action: ACCEPT
reason: >-
This is a core function. ASCL1 overexpression increases neurogenesis, and
it is required for
neuronal differentiation in multiple lineages.
supported_by:
- reference_id: PMID:19008346
supporting_text: "By overexpressing one of these, the transcription factor
ASCL1, we were able to regain neurogenesis from hNPC(VM) cultures"
- term:
id: GO:0045686
label: negative regulation of glial cell differentiation
evidence_type: TAS
original_reference_id: PMID:17166924
review:
summary: >-
ASCL1 suppresses glial (astrocyte) fate, promoting neuronal and oligodendrocyte
lineages over astroglial lineage.
Genetic fate mapping shows ASCL1 is present in progenitors to neurons and
oligodendrocytes but not astrocytes.
action: NEW
reason: >-
ASCL1 actively suppresses gliogenesis (specifically astrocyte differentiation)
as part of its role in the
neuron-glia binary fate decision. Ascl1-null cells have diminished neuronal
differentiation capacity and
retain characteristics of immature glial cells (PMID:17166924). This annotation
is missing and represents
a core function of ASCL1 in lineage specification.
supported_by:
- reference_id: PMID:17166924
supporting_text: "We find that Ascl1 is present in progenitors to both neurons
and oligodendrocytes, but not astrocytes."
- term:
id: GO:0048663
label: neuron fate commitment
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
ASCL1 is required for neuron fate commitment, functioning early in neurogenesis
to commit
progenitors to neuronal lineages.
action: ACCEPT
reason: >-
Neuron fate commitment is a core function. ASCL1 expression marks the transition
from cycling
progenitors to postmitotic neurons (PMID:36931659).
supported_by:
- reference_id: PMID:36931659
supporting_text: "endogenous expression of ASCL1 drives progenitor differentiation"
- term:
id: GO:0048665
label: neuron fate specification
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
ASCL1 specifies neuronal fate, particularly GABAergic interneurons in the
cortex and
noradrenergic neurons in the autonomic nervous system.
action: ACCEPT
reason: >-
Neuron fate specification is a core function. ASCL1 specifies particular neuronal
subtypes
including GABAergic interneurons (PMID:12050665) and noradrenergic neurons
(PMID:14532329).
supported_by:
- reference_id: PMID:12050665
supporting_text: "One lineage expresses Dlx1/2 and Mash1 transcription factors"
- reference_id: PMID:14532329
supporting_text: "All HASH-1 mutant alleles impaired noradrenergic neuronal
development"
- term:
id: GO:0048666
label: neuron development
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
ASCL1 is essential for neuron development broadly, encompassing differentiation
and maturation.
action: ACCEPT
reason: >-
Neuron development is a core function. This broader term encompasses the more
specific
neuronal differentiation and fate commitment functions.
supported_by:
- reference_id: PMID:10903890
supporting_text: "essential for proper development of olfactory and most
peripheral autonomic neurons"
- term:
id: GO:0051593
label: response to folic acid
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
This annotation is transferred from model organisms. The functional relevance
to human ASCL1
is unclear without supporting literature.
action: UNDECIDED
reason: >-
Unable to verify relevance of folic acid response for human ASCL1 without
access to the
primary evidence. This may represent a peripheral phenotype from model organisms.
- term:
id: GO:0060579
label: ventral spinal cord interneuron fate commitment
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
ASCL1 functions with FOXN4 in specifying V2b interneurons in the spinal cord,
as documented
in UniProt and ISS annotations.
action: ACCEPT
reason: >-
This is a specific neuronal fate commitment function supported by the UniProt
record stating
ASCL1 acts synergistically with FOXN4 to specify V2b neurons from p2 progenitors.
supported_by:
- reference_id: UniProt:P50553
supporting_text: "Acts synergistically with FOXN4 to specify the identity
of V2b neurons rather than V2a from bipotential p2 progenitors during
spinal cord neurogenesis"
- term:
id: GO:0061549
label: sympathetic ganglion development
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
ASCL1 is required for sympathetic nervous system development, including sympathetic
ganglia.
This is supported by NAS evidence from PMID:10903890.
action: ACCEPT
reason: >-
Sympathetic ganglion development is related to the autonomic neuron development
function of
ASCL1, which is well-documented.
supported_by:
- reference_id: PMID:10903890
supporting_text: "essential for proper development of... most peripheral
autonomic neurons"
- term:
id: GO:0070849
label: response to epidermal growth factor
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
This annotation is transferred from model organisms. The functional relevance
to human ASCL1
is unclear without supporting literature.
action: UNDECIDED
reason: >-
Unable to verify relevance of EGF response for human ASCL1 without access
to primary evidence.
May represent regulatory effects on ASCL1 expression rather than a core function.
- term:
id: GO:0071259
label: cellular response to magnetism
evidence_type: IEA
original_reference_id: GO_REF:0000107
review:
summary: >-
This is an unusual annotation likely transferred from a specific study. The
functional relevance
is unclear and this does not represent a core ASCL1 function.
action: UNDECIDED
reason: >-
This appears to be a highly specific phenotype from model organism studies.
Without access to
the primary evidence, cannot evaluate the relevance to human ASCL1 function.
- term:
id: GO:0003676
label: nucleic acid binding
evidence_type: EXP
original_reference_id: PMID:28402879
review:
summary: >-
This NMR study characterized the conformational dynamics of ASCL1 protein.
While it confirms
DNA binding capacity, the term is too general given the available specific
annotations.
action: MARK_AS_OVER_ANNOTATED
reason: >-
The term "nucleic acid binding" is too general. ASCL1 specifically binds double-stranded
DNA
at E-box sequences. More specific terms are already annotated with experimental
evidence.
proposed_replacement_terms:
- id: GO:0070888
label: E-box binding
- id: GO:1990837
label: sequence-specific double-stranded DNA binding
supported_by:
- reference_id: PMID:28402879
supporting_text: "it is well known that Ascl1 binds DNA as a homo- or heterodimer
via its basic helix-loop-helix (bHLH) motif"
- term:
id: GO:1990837
label: sequence-specific double-stranded DNA binding
evidence_type: IDA
original_reference_id: PMID:28473536
review:
summary: >-
This high-throughput SELEX study characterized DNA binding specificities of
human transcription
factors including ASCL1. It confirms sequence-specific binding to E-box motifs.
action: ACCEPT
reason: >-
This is a core molecular function with direct experimental evidence. The SELEX
method provides
systematic characterization of DNA binding specificity.
supported_by:
- reference_id: PMID:28473536
supporting_text: "By analysis of 542 human TFs with methylation-sensitive
SELEX... we found that there are also many TFs that prefer CpG-methylated
sequences"
- term:
id: GO:0000785
label: chromatin
evidence_type: ISA
original_reference_id: GO_REF:0000113
review:
summary: >-
ASCL1 binds chromatin as a pioneer transcription factor. This annotation from
the TFClass
database reflects ASCL1's chromatin association.
action: ACCEPT
reason: >-
ASCL1 associates with chromatin where it binds nucleosomal DNA and recruits
chromatin remodelers.
The pioneer factor activity (PMID:36931659) supports chromatin localization.
supported_by:
- reference_id: PMID:36931659
supporting_text: "Pioneer transcription factors are thought to play pivotal
roles in developmental processes by binding nucleosomal DNA"
- term:
id: GO:0000981
label: DNA-binding transcription factor activity, RNA polymerase
II-specific
evidence_type: ISA
original_reference_id: GO_REF:0000113
review:
summary: >-
This ISA annotation from TFClass is correct and consistent with ASCL1's function
as a bHLH
transcription factor regulating Pol II-dependent transcription.
action: ACCEPT
reason: >-
This is a core molecular function. Consistent with IBA annotation and experimental
evidence.
supported_by:
- reference_id: PMID:10903890
supporting_text: "The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro,
and transactivates an E-box containing reporter construct in vivo."
- term:
id: GO:0045666
label: positive regulation of neuron differentiation
evidence_type: ISS
original_reference_id: GO_REF:0000024
review:
summary: >-
ISS annotation consistent with ASCL1's role as a proneural factor promoting
neuronal differentiation.
action: ACCEPT
reason: >-
This is a core function with multiple supporting evidence types. The ISS is
consistent with
IBA and IEA annotations for the same term.
supported_by:
- reference_id: PMID:19008346
supporting_text: "By overexpressing one of these, the transcription factor
ASCL1, we were able to regain neurogenesis"
- term:
id: GO:0030182
label: neuron differentiation
evidence_type: ISS
original_reference_id: GO_REF:0000024
review:
summary: >-
ISS annotation for neuron differentiation, consistent with multiple other
evidence types.
action: ACCEPT
reason: >-
Core function with abundant supporting evidence across multiple annotation
types.
supported_by:
- reference_id: PMID:10903890
supporting_text: "essential for proper development of olfactory and most
peripheral autonomic neurons"
- term:
id: GO:0048663
label: neuron fate commitment
evidence_type: ISS
original_reference_id: GO_REF:0000024
review:
summary: >-
ISS annotation for neuron fate commitment, consistent with ASCL1's proneural
function.
action: ACCEPT
reason: >-
Core function supported by multiple evidence types and extensive literature.
supported_by:
- reference_id: PMID:36931659
supporting_text: "endogenous expression of ASCL1 drives progenitor differentiation"
- term:
id: GO:0048665
label: neuron fate specification
evidence_type: ISS
original_reference_id: GO_REF:0000024
review:
summary: >-
ISS annotation for neuron fate specification, consistent with ASCL1's role
in specifying
neuronal subtypes.
action: ACCEPT
reason: >-
Core function supported by experimental evidence for specific neuronal subtype
specification.
supported_by:
- reference_id: PMID:12050665
supporting_text: "One lineage expresses Dlx1/2 and Mash1 transcription factors,
represents 65% of neocortical GABAergic neurons"
- term:
id: GO:0048666
label: neuron development
evidence_type: ISS
original_reference_id: GO_REF:0000024
review:
summary: >-
ISS annotation for neuron development, consistent with ASCL1's essential role
in neurogenesis.
action: ACCEPT
reason: >-
Core function supported by extensive literature and multiple evidence types.
supported_by:
- reference_id: PMID:10903890
supporting_text: "essential for proper development of olfactory and most
peripheral autonomic neurons"
- term:
id: GO:0000122
label: negative regulation of transcription by RNA polymerase II
evidence_type: IDA
original_reference_id: PMID:11736660
review:
summary: >-
ASCL1 represses PACE4 gene transcription via E-box binding. This demonstrates
transcriptional
repressor activity in addition to its better-known activator function.
action: ACCEPT
reason: >-
ASCL1 functions as both activator and repressor depending on target gene and
context. The
repression of PACE4 is directly demonstrated by this study.
supported_by:
- reference_id: PMID:11736660
supporting_text: "The overexpression of hASH-1 or MASH-1 causes a marked
decrease in endogenous PACE4 gene expression"
- term:
id: GO:0000978
label: RNA polymerase II cis-regulatory region sequence-specific DNA
binding
evidence_type: IDA
original_reference_id: PMID:11736660
review:
summary: >-
ASCL1 binds to the cis-regulatory E-box cluster in the PACE4 promoter to regulate
transcription.
action: ACCEPT
reason: >-
This is a core molecular function with direct experimental evidence from gel
shift assays
demonstrating binding to the PACE4 promoter E-box cluster.
supported_by:
- reference_id: PMID:11736660
supporting_text: "Binding of hASH-1 to the E-box cluster was confirmed by
gel mobility-shift assay"
- term:
id: GO:0001227
label: DNA-binding transcription repressor activity, RNA polymerase
II-specific
evidence_type: IDA
original_reference_id: PMID:11736660
review:
summary: >-
ASCL1 functions as a transcriptional repressor of the PACE4 gene. This demonstrates
context-
dependent repressor activity.
action: ACCEPT
reason: >-
This is a documented molecular function of ASCL1. While primarily known as
an activator,
ASCL1 can repress specific target genes like PACE4 via E-box binding.
supported_by:
- reference_id: PMID:11736660
supporting_text: "The overexpression of hASH-1 or MASH-1 causes a marked
decrease in endogenous PACE4 gene expression"
- term:
id: GO:0060579
label: ventral spinal cord interneuron fate commitment
evidence_type: ISS
original_reference_id: GO_REF:0000024
review:
summary: >-
ISS annotation consistent with ASCL1's role in V2b interneuron specification
in spinal cord.
action: ACCEPT
reason: >-
Consistent with UniProt annotation describing ASCL1's function with FOXN4
in V2b specification.
supported_by:
- reference_id: UniProt:P50553
supporting_text: "Acts synergistically with FOXN4 to specify the identity
of V2b neurons"
- term:
id: GO:0003358
label: noradrenergic neuron development
evidence_type: ISS
original_reference_id: GO_REF:0000024
review:
summary: >-
ISS annotation consistent with ASCL1's essential role in noradrenergic neuron
development.
action: ACCEPT
reason: >-
Consistent with IMP evidence from PMID:14532329 demonstrating impaired noradrenergic
development
with ASCL1 mutations.
supported_by:
- reference_id: PMID:14532329
supporting_text: "All HASH-1 mutant alleles impaired noradrenergic neuronal
development"
- term:
id: GO:0010468
label: regulation of gene expression
evidence_type: ISS
original_reference_id: GO_REF:0000024
review:
summary: >-
ASCL1 regulates gene expression as a transcription factor. This is a very
general term.
action: MARK_AS_OVER_ANNOTATED
reason: >-
While correct, this term is too general. More specific terms like "regulation
of transcription
by RNA polymerase II" are more informative and already annotated.
proposed_replacement_terms:
- id: GO:0006357
label: regulation of transcription by RNA polymerase II
- term:
id: GO:0061549
label: sympathetic ganglion development
evidence_type: ISS
original_reference_id: GO_REF:0000024
review:
summary: >-
ISS annotation consistent with ASCL1's role in autonomic nervous system development.
action: ACCEPT
reason: >-
Consistent with ASCL1's essential role in peripheral autonomic neuron development.
supported_by:
- reference_id: PMID:10903890
supporting_text: "essential for proper development of... most peripheral
autonomic neurons"
- term:
id: GO:0045892
label: negative regulation of DNA-templated transcription
evidence_type: IDA
original_reference_id: PMID:11736660
review:
summary: >-
ASCL1 negatively regulates transcription of the PACE4 gene. This is a more
general term
than the Pol II-specific repression annotation.
action: ACCEPT
reason: >-
This is demonstrated by the PACE4 repression study. Slightly more general
than GO:0000122
but both are correct.
supported_by:
- reference_id: PMID:11736660
supporting_text: "The overexpression of hASH-1 or MASH-1 causes a marked
decrease in endogenous PACE4 gene expression"
- term:
id: GO:0005634
label: nucleus
evidence_type: IDA
original_reference_id: PMID:12858003
review:
summary: >-
Nuclear localization demonstrated by immunohistochemistry in pulmonary neuroendocrine
cells.
action: ACCEPT
reason: >-
Core cellular component annotation with direct experimental evidence.
supported_by:
- reference_id: PMID:12858003
supporting_text: "Immunohistochemically, pulmonary neuroendocrine cells
(PNECs) are positive for Mash1"
- term:
id: GO:0003359
label: noradrenergic neuron fate commitment
evidence_type: IMP
original_reference_id: PMID:14532329
review:
summary: >-
HASH-1 mutations impair noradrenergic neuronal fate commitment, as shown by
mutation analysis
in CCHS patients and in vitro models.
action: ACCEPT
reason: >-
Core function with IMP evidence. Mutations in ASCL1 cause noradrenergic neuron
development
defects, demonstrating its essential role in fate commitment.
supported_by:
- reference_id: PMID:14532329
supporting_text: "All HASH-1 mutant alleles impaired noradrenergic neuronal
development, when overexpressed from adenoviral constructs."
- term:
id: GO:0021892
label: cerebral cortex GABAergic interneuron differentiation
evidence_type: IEP
original_reference_id: PMID:12050665
review:
summary: >-
ASCL1 (Mash1) is expressed in progenitors that give rise to GABAergic interneurons
in human
neocortex, marking this specific lineage.
action: ACCEPT
reason: >-
This is a specific neuronal differentiation function supported by expression
pattern analysis
in human fetal cortex.
supported_by:
- reference_id: PMID:12050665
supporting_text: "One lineage expresses Dlx1/2 and Mash1 transcription factors,
represents 65% of neocortical GABAergic neurons in humans, and originates
from Mash1-expressing progenitors"
- term:
id: GO:0032526
label: response to retinoic acid
evidence_type: IEP
original_reference_id: PMID:12000752
review:
summary: >-
ASCL1 expression is rapidly reduced in response to retinoic acid treatment
in neuroblastoma
cells undergoing differentiation.
action: KEEP_AS_NON_CORE
reason: >-
ASCL1 expression responds to retinoic acid (downregulation), but this represents
regulation
OF ASCL1 rather than a primary function of ASCL1.
supported_by:
- reference_id: PMID:12000752
supporting_text: "expression of neuroblast-specific ASCL1 (HASH-1) gene
was promptly reduced after RA treatment"
- term:
id: GO:0043425
label: bHLH transcription factor binding
evidence_type: IPI
original_reference_id: PMID:11940670
review:
summary: >-
ASCL1 interacts with E12, a bHLH transcription factor, and this interaction
protects ASCL1
from Notch-induced degradation.
action: ACCEPT
reason: >-
This is a core molecular function. ASCL1 requires heterodimerization with
bHLH E-proteins
for DNA binding and stability.
supported_by:
- reference_id: PMID:11940670
supporting_text: "Overexpression of the hASH1-dimerizing partner E12 could
protect hASH1 from degradation"
- term:
id: GO:0045665
label: negative regulation of neuron differentiation
evidence_type: IDA
original_reference_id: PMID:12000752
review:
summary: >-
This annotation seems inconsistent with ASCL1's primary role as a positive
regulator of
neuronal differentiation. The paper shows ASCL1 is downregulated during differentiation.
action: REMOVE
reason: >-
The cited paper (PMID:12000752) shows that ASCL1 expression is reduced during
RA-induced
differentiation, not that ASCL1 negatively regulates differentiation. ASCL1
is a proneural
factor that promotes differentiation. This annotation appears to be an error
in interpretation.
supported_by:
- reference_id: PMID:12000752
supporting_text: "expression of neuroblast-specific ASCL1 (HASH-1) gene
was promptly reduced after RA treatment"
- term:
id: GO:0060487
label: lung epithelial cell differentiation
evidence_type: NAS
original_reference_id: PMID:12858003
review:
summary: >-
ASCL1 (hASH1) is specifically involved in neuroendocrine differentiation within
lung epithelium,
not general lung epithelial cell differentiation.
action: MODIFY
reason: >-
ASCL1 is specifically required for pulmonary neuroendocrine cell differentiation,
not general
lung epithelial differentiation. A more specific term would be more accurate.
proposed_replacement_terms:
- id: GO:0061100
label: lung neuroendocrine cell differentiation
supported_by:
- reference_id: PMID:12858003
supporting_text: "Moreover, studies of small cell carcinoma and non- small
cell carcinoma suggest that neuroendocrine differentiation could be regulated
by hASH1"
- term:
id: GO:0070888
label: E-box binding
evidence_type: IDA
original_reference_id: PMID:11736660
review:
summary: >-
ASCL1 binds E-box sequences in the PACE4 promoter, confirmed by gel mobility-shift
assay.
action: ACCEPT
reason: >-
This is a core molecular function with direct experimental evidence.
supported_by:
- reference_id: PMID:11736660
supporting_text: "Binding of hASH-1 to the E-box cluster was confirmed by
gel mobility-shift assay"
- term:
id: GO:0003700
label: DNA-binding transcription factor activity
evidence_type: IDA
original_reference_id: PMID:10903890
review:
summary: >-
ASCL1 functions as a transcription factor, binding DNA and transactivating
reporter genes.
action: ACCEPT
reason: >-
Core molecular function with direct experimental evidence from reporter assays.
supported_by:
- reference_id: PMID:10903890
supporting_text: "The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro,
and transactivates an E-box containing reporter construct in vivo"
- term:
id: GO:0043425
label: bHLH transcription factor binding
evidence_type: IPI
original_reference_id: PMID:10903890
review:
summary: >-
ASCL1 interacts with E2-2 (TCF4), a bHLH transcription factor, demonstrated
by yeast two-hybrid
and co-immunoprecipitation.
action: ACCEPT
reason: >-
Core molecular function. Heterodimerization with E-proteins is essential for
ASCL1 DNA binding
and transcriptional activity.
supported_by:
- reference_id: PMID:10903890
supporting_text: "E2-2 interacts with HASH-1 in both yeast and mammalian
cells"
- term:
id: GO:0045944
label: positive regulation of transcription by RNA polymerase II
evidence_type: IDA
original_reference_id: PMID:10903890
review:
summary: >-
ASCL1 transactivates E-box containing reporter genes when complexed with E-proteins.
action: ACCEPT
reason: >-
Core function with direct experimental evidence from reporter assays.
supported_by:
- reference_id: PMID:10903890
supporting_text: "transactivates an E-box containing reporter construct
in vivo"
- term:
id: GO:0048485
label: sympathetic nervous system development
evidence_type: NAS
original_reference_id: PMID:10903890
review:
summary: >-
ASCL1 is essential for development of peripheral autonomic neurons, which
includes the
sympathetic nervous system.
action: ACCEPT
reason: >-
This is a core biological process supported by the evidence for autonomic
neuron development.
supported_by:
- reference_id: PMID:10903890
supporting_text: "essential for proper development of... most peripheral
autonomic neurons"
- term:
id: GO:0070888
label: E-box binding
evidence_type: IDA
original_reference_id: PMID:10903890
review:
summary: >-
ASCL1/E2-2 complex binds E-box sequence (CACCTG) demonstrated by in vitro
binding assays.
action: ACCEPT
reason: >-
Core molecular function with direct experimental evidence. Duplicate entry
with different
reference supporting the same function.
supported_by:
- reference_id: PMID:10903890
supporting_text: "The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro"
- term:
id: GO:0007219
label: Notch signaling pathway
evidence_type: IDA
original_reference_id: PMID:16160079
review:
summary: >-
ASCL1 is regulated by and functions within the Notch signaling pathway. Notch1
activation
represses ASCL1 expression.
action: ACCEPT
reason: >-
ASCL1 is a key component of the Notch signaling pathway, acting downstream
of Notch (repressed
by active Notch). It also activates DLL1/DLL3 which modulate Notch signaling.
supported_by:
- reference_id: PMID:16160079
supporting_text: "Notch1 pathway activation led to an increase in hairy
enhancer of split 1 (HES-1) protein and a concomitant silencing of human
Notch1/HES-1/achaete-scute homolog 1"
- reference_id: PMID:11940670
supporting_text: "Notch signaling induces rapid degradation of achaete-scute
homolog 1"
- term:
id: GO:0005634
label: nucleus
evidence_type: IDA
original_reference_id: PMID:17507989
review:
summary: >-
Nuclear localization demonstrated by immunohistochemistry and functional studies.
action: ACCEPT
reason: >-
Core cellular component with direct experimental evidence. Multiple IDA entries
support this.
supported_by:
- reference_id: PMID:17507989
supporting_text: "Constitutive expression of human ASH-1 (hASH1) in mouse
lung"
- term:
id: GO:0005634
label: nucleus
evidence_type: IDA
original_reference_id: PMID:18311112
review:
summary: >-
Nuclear localization demonstrated by immunohistochemistry in prostate cancer
cells with
neuroendocrine differentiation.
action: ACCEPT
reason: >-
Core cellular component with direct experimental evidence.
supported_by:
- reference_id: PMID:18311112
supporting_text: "Human ASH1 protein was analyzed by immunohistochemistry"
- term:
id: GO:0022008
label: neurogenesis
evidence_type: IDA
original_reference_id: PMID:19008346
review:
summary: >-
ASCL1 overexpression increases neurogenesis in human neural progenitor cells.
action: ACCEPT
reason: >-
Core biological process with direct experimental evidence showing increased
neuron production
upon ASCL1 overexpression.
supported_by:
- reference_id: PMID:19008346
supporting_text: "By overexpressing one of these, the transcription factor
ASCL1, we were able to regain neurogenesis from hNPC(VM) cultures"
- term:
id: GO:0043066
label: negative regulation of apoptotic process
evidence_type: IMP
original_reference_id: PMID:17507989
review:
summary: >-
ASCL1 expression confers resistance to apoptosis in lung epithelial cells.
Knockdown increases
apoptosis in lung cancer cells.
action: KEEP_AS_NON_CORE
reason: >-
This is a documented function of ASCL1 but represents a downstream effect
rather than a
primary function. It is relevant to ASCL1's role in cancer but not its core
developmental
neurogenesis function.
supported_by:
- reference_id: PMID:17507989
supporting_text: "Knockdown of hASH1 gene in human lung cancer cells in
vitro suppressed growth by increasing apoptosis. We also show that forced
expression of hASH1 in immortalized human bronchial epithelial cells decreases
apoptosis."
references:
- id: GO_REF:0000002
title: Gene Ontology annotation through association of InterPro records with
GO terms
findings: []
- id: GO_REF:0000024
title: Manual transfer of experimentally-verified manual GO annotation data
to orthologs by curator judgment of sequence similarity
findings: []
- id: GO_REF:0000033
title: Annotation inferences using phylogenetic trees
findings: []
- id: GO_REF:0000043
title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword
mapping
findings: []
- id: GO_REF:0000107
title: Automatic transfer of experimentally verified manual GO annotation
data to orthologs using Ensembl Compara
findings: []
- id: GO_REF:0000113
title: Gene Ontology annotation of human sequence-specific DNA binding
transcription factors (DbTFs) based on the TFClass database
findings: []
- id: GO_REF:0000117
title: Electronic Gene Ontology annotations created by ARBA machine learning
models
findings: []
- id: GO_REF:0000120
title: Combined Automated Annotation using Multiple IEA Methods
findings: []
- id: PMID:10903890
title: HASH-1 and E2-2 are expressed in human neuroblastoma cells and form a
functional complex.
findings:
- statement: ASCL1 (HASH-1) interacts with E2-2 (TCF4) in yeast and
mammalian cells
- statement: The HASH-1/E2-2 complex binds E-box sequence CACCTG in vitro
- statement: The complex transactivates E-box containing reporter
constructs
- statement: E2-2 is a major HASH-1 interacting protein in neuroblastoma
cells
- id: PMID:11736660
title: Proprotein convertase PACE4 is down-regulated by the basic
helix-loop-helix transcription factor hASH-1 and MASH-1.
findings:
- statement: ASCL1 binds to E-box cluster in PACE4 promoter (gel shift
assay)
- statement: ASCL1 overexpression represses PACE4 gene expression
- statement: ASCL1 functions as a transcriptional repressor for specific
targets
- id: PMID:11940670
title: Notch signaling induces rapid degradation of achaete-scute homolog 1.
findings:
- statement: Notch1 activation induces rapid degradation of ASCL1 protein
- statement: ASCL1 degradation is proteasome-dependent and involves
ubiquitination
- statement: E12 dimerization protects ASCL1 from Notch-induced
degradation
- id: PMID:12000752
title: Activation of the phosphatidylinositol 3-kinase/Akt signaling pathway
by retinoic acid is required for neural differentiation of SH-SY5Y human
neuroblastoma cells.
findings:
- statement: ASCL1 expression is rapidly reduced upon retinoic acid
treatment
- statement: This occurs during neuroblastoma cell differentiation
- id: PMID:12050665
title: Origin of GABAergic neurons in the human neocortex.
findings:
- statement: Mash1/ASCL1 marks a lineage representing 65% of human
neocortical GABAergic neurons
- statement: These originate from Mash1-expressing progenitors in the
dorsal forebrain
- id: PMID:12858003
title: Mechanisms of neuroendocrine differentiation in pulmonary
neuroendocrine cells and small cell carcinoma.
findings:
- statement: ASCL1 (hASH1) regulates neuroendocrine differentiation in
lung
- statement: Nuclear expression in pulmonary neuroendocrine cells
- id: PMID:14532329
title: Noradrenergic neuronal development is impaired by mutation of the
proneural HASH-1 gene in congenital central hypoventilation syndrome
(Ondine's curse).
findings:
- statement: HASH-1 mutations impair noradrenergic neuronal development
- statement: ASCL1 functions in the HASH-PHOX-RET pathway controlling
noradrenergic neurons
- id: PMID:16160079
title: Conservation of the Notch1 signaling pathway in gastrointestinal
carcinoid cells.
findings:
- statement: Notch1 activation silences ASCL1 expression
- statement: ASCL1 is part of Notch signaling pathway in neuroendocrine
cells
- id: PMID:17507989
title: Achaete-scute homolog-1 linked to remodeling and preneoplasia of
pulmonary epithelium.
findings:
- statement: ASCL1 expression confers resistance to apoptosis
- statement: Knockdown increases apoptosis in lung cancer cells
- statement: Nuclear localization demonstrated
- id: file:human/ASCL1/ASCL1-deep-research-cyberian.md
title: Cyberian deep research on ASCL1 functional annotation
findings:
- statement: Comprehensive review of ASCL1 as a pioneer transcription
factor
- statement: ASCL1 preferentially binds CAGCTG E-box motif
- statement: ASCL1 operates through two mechanisms - classical pioneer and
mSWI/SNF-dependent
- statement: Oscillatory ASCL1 expression maintains progenitors; sustained
expression drives differentiation
- statement: ASCL1 is a lineage oncogene in small cell lung cancer
- id: PMID:8390674
title: Identification of a human achaete-scute homolog highly expressed in
neuroendocrine tumors.
findings:
- statement: Human ASCL1 cloned and characterized
- statement: 95% identity with mouse Mash1
- statement: Highly expressed in neuroendocrine tumors including SCLC
- id: PMID:8221886
title: Mammalian achaete-scute homolog 1 is required for the early
development of olfactory and autonomic neurons.
findings:
- statement: Mash1-null mice die shortly after birth due to breathing and
feeding defects
- statement: ASCL1 essential for olfactory epithelium, sympathetic,
parasympathetic, and enteric ganglia development
- statement: ASCL1 acts as a determination gene in olfactory system
- id: PMID:20107439
title: Direct conversion of fibroblasts to functional neurons by defined
factors.
findings:
- statement: ASCL1 with BRN2 and MYT1L directly converts fibroblasts to
functional neurons
- statement: ASCL1 alone sufficient to induce immature iN cells
- statement: Induced neurons express neuron-specific proteins and form
functional synapses
- id: PMID:21536733
title: A novel function of the proneural factor Ascl1 in progenitor
proliferation identified by genome-wide characterization of its targets.
findings:
- statement: Over 21,000 ASCL1 binding sites mapped genome-wide
- statement: 272 high-confidence direct targets identified
- statement: ASCL1 directly controls cell cycle genes - unexpected for
proneural factor
- statement: ASCL1 required for normal neural progenitor proliferation
- id: PMID:24243019
title: Hierarchical mechanisms for direct reprogramming of fibroblasts to
neurons.
findings:
- statement: ASCL1 binds trivalent chromatin signature (H3K9me3, H3K27ac,
H3K4me1)
- statement: ASCL1 acts first to open chromatin, enabling BRN2 binding
- statement: ASCL1 binding patterns identical alone or with partners
- id: PMID:24179156
title: Oscillatory control of factors determining multipotency and fate in
mouse neural progenitors.
findings:
- statement: ASCL1 levels oscillate with 2-3 hour period in neural
progenitors
- statement: Oscillation driven by Hes1 repression of ASCL1
- statement: Oscillatory expression maintains progenitors; sustained
expression drives differentiation
- id: PMID:25267614
title: ASCL1 is a lineage oncogene providing therapeutic targets for
high-grade neuroendocrine lung cancers.
findings:
- statement: ASCL1 is a lineage oncogene in SCLC
- statement: ASCL1 knockdown induces apoptosis specifically in
ASCL1-positive cancer lines
- statement: BCL2 is a key ASCL1 target in SCLC
- statement: 72-gene ASCL1 signature predicts poor prognosis
- id: PMID:25753420
title: Ascl1 Coordinately Regulates Gene Expression and the Chromatin
Landscape during Neurogenesis.
findings:
- statement: ASCL1 functions as a pioneer transcription factor
- statement: ASCL1 binds closed chromatin and initiates chromatin
remodeling
- statement: 63% of ASCL1 binding sites at distal enhancers
- id: PMID:27452466
title: ASCL1 and NEUROD1 Reveal Heterogeneity in Pulmonary Neuroendocrine
Tumors and Regulate Distinct Genetic Programs.
findings:
- statement: SCLC classified into ASCL1-high (75%), NEUROD1-high (15%),
and other subtypes
- statement: ASCL1 and NEUROD1 occupy non-overlapping genomic sites
- statement: Only ASCL1 (not NEUROD1) required for SCLC tumor formation
- statement: ASCL1 directly targets MYCL1, RET, SOX2, NFIB
- id: PMID:31086315
title: Proneural factors Ascl1 and Neurog2 contribute to neuronal subtype
identities by establishing distinct chromatin landscapes.
findings:
- statement: ASCL1 and Neurog2 bind largely non-overlapping genomic sites
- statement: ASCL1 drives GABAergic and sympathetic neuronal fates
- statement: Neurog2 promotes glutamatergic and sensory neuronal
identities
- id: PMID:24821983
title: The phosphorylation status of Ascl1 is a key determinant of neuronal
differentiation.
findings:
- statement: ASCL1 phosphorylated on serine-proline sites by CDK-cyclin
complexes
- statement: Phosphorylated ASCL1 has reduced DNA binding and
transcriptional activity
- statement: Phospho-mutant ASCL1 shows enhanced neuronal induction
activity
- id: PMID:27076429
title: Ascl1 Is Required for the Development of Specific Neuronal Subtypes
in the Enteric Nervous System.
findings:
- statement: All enteric neuronal subtypes derive from ASCL1-expressing
progenitors
- statement: Calbindin, TH, and VIP neurons selectively decreased in
Ascl1-knockout
- statement: Serotonergic neurons form normally
- statement: Esophageal neurons fail to form entirely
- id: PMID:31819055
title: ASCL1 is a MYCN- and LMO1-dependent member of the adrenergic
neuroblastoma core regulatory circuitry.
findings:
- statement: ASCL1 is member of core regulatory circuitry in neuroblastoma
- statement: MYCN directly regulates ASCL1 expression
- statement: ASCL1 deletion results in slower neuroblastoma growth
- id: PMID:18311112
title: Human ASH1 expression in prostate cancer with neuroendocrine
differentiation.
findings:
- statement: Nuclear localization by immunohistochemistry
- statement: Expression correlates with neuroendocrine differentiation
- id: PMID:19008346
title: Regionally specified human neural progenitor cells derived from the
mesencephalon and forebrain undergo increased neurogenesis following
overexpression of ASCL1.
findings:
- statement: ASCL1 overexpression increases neurogenesis in human neural
progenitors
- statement: Effect is region-specific
- id: PMID:28402879
title: Fragment-Based NMR Study of the Conformational Dynamics in the bHLH
Transcription Factor Ascl1.
findings:
- statement: NMR characterization of ASCL1 structure
- statement: Confirms DNA binding via bHLH domain
- id: PMID:28473536
title: Impact of cytosine methylation on DNA binding specificities of human
transcription factors.
findings:
- statement: Systematic SELEX analysis of DNA binding specificity
- statement: Confirms sequence-specific DNA binding
- id: PMID:32296183
title: A reference map of the human binary protein interactome.
findings:
- statement: High-throughput protein-protein interaction study (HuRI)
- id: PMID:33961781
title: Dual proteome-scale networks reveal cell-specific remodeling of the
human interactome.
findings:
- statement: BioPlex proteome-scale interaction network
- id: PMID:36931659
title: Pioneer factor ASCL1 cooperates with the mSWI/SNF complex at distal
regulatory elements to regulate human neural differentiation.
findings:
- statement: ASCL1 has pioneer transcription factor activity
- statement: Interacts with mSWI/SNF chromatin remodeling complexes
(ARID1A, SMARCC1)
- statement: Binds nucleosomal DNA and remodels chromatin at neuronal
enhancers
- statement: Drives progenitor differentiation into postmitotic neurons
- id: PMID:17166924
title: Ascl1 defines sequentially generated lineage-restricted neuronal and
oligodendrocyte precursor cells in the spinal cord.
findings:
- statement: Ascl1 is present in progenitors to neurons and
oligodendrocytes, but not astrocytes
supporting_text: "We find that Ascl1 is present in progenitors to both neurons
and oligodendrocytes, but not astrocytes."
- statement: Ascl1-null cells have diminished neuronal differentiation
capacity
supporting_text: "Ascl1-null cells in the spinal cord have a diminished capacity
to undergo neuronal differentiation, with a subset of these cells retaining
characteristics of immature glial cells."
core_functions:
- molecular_function:
id: GO:0000981
label: DNA-binding transcription factor activity, RNA polymerase
II-specific
description: >-
ASCL1 is a bHLH transcription factor that binds E-box motifs (CANNTG) as a heterodimer
with
E-proteins (TCF3, TCF4) and regulates transcription of neuronal target genes.
supported_by:
- reference_id: PMID:10903890
supporting_text: "The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro,
and transactivates an E-box containing reporter construct in vivo."
- reference_id: PMID:11736660
supporting_text: "Binding of hASH-1 to the E-box cluster was confirmed by
gel mobility-shift assay"
- molecular_function:
id: GO:0070888
label: E-box binding
description: >-
ASCL1 specifically binds E-box sequences with strong preference for the CAGCTG
variant, which
is enriched directly beneath 74% of ASCL1 binding peaks (PMID:21536733). This
"GC" core E-box
preference distinguishes ASCL1 from Neurog2 (which prefers CAGATG), explaining
their distinct
neuronal subtype outputs. E-proteins enhance ASCL1 binding to CAGSTG sequences
through
heterodimerization.
supported_by:
- reference_id: PMID:10903890
supporting_text: "The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro"
- reference_id: PMID:11736660
supporting_text: "Binding of hASH-1 to the E-box cluster was confirmed by
gel mobility-shift assay"
- reference_id: PMID:21536733
supporting_text: "CAGCTG E-box motif is highly enriched directly beneath 74%
of ASCL1 binding peaks"
- molecular_function:
id: GO:0003682
label: chromatin binding
description: >-
ASCL1 functions as a pioneer factor capable of binding nucleosomal DNA and initiating
chromatin
remodeling at neuronal enhancers. Studies reveal ASCL1 operates through two
distinct mechanisms:
at ~23.5% of sites it functions as a classical pioneer factor binding closed
chromatin
independently, while at ~68% of sites it requires cooperation with mSWI/SNF
chromatin
remodeling complexes (PMID:36931659). ASCL1 binds chromatin marked by a trivalent
signature
(H3K9me3, H3K27ac, H3K4me1) and predominantly at distal enhancers (~63%) rather
than
promoters (~7%) (PMID:25753420).
supported_by:
- reference_id: PMID:36931659
supporting_text: "Pioneer transcription factors are thought to play pivotal
roles in developmental processes by binding nucleosomal DNA to activate
gene expression"
- reference_id: PMID:25753420
supporting_text: "ASCL1 binding sites are predominantly at distal enhancers"
- reference_id: PMID:24243019
supporting_text: "ASCL1 binds trivalent chromatin signature and acts first
to open chromatin"
- molecular_function:
id: GO:0043425
label: bHLH transcription factor binding
description: >-
ASCL1 heterodimerizes with E-proteins (TCF3/E12/E47, TCF4/E2-2) via its HLH
domain. This
dimerization is essential for DNA binding, transcriptional activity, and protein
stability.
supported_by:
- reference_id: PMID:10903890
supporting_text: "We show that E2-2 interacts with HASH-1 in both yeast and
mammalian cells."
- reference_id: PMID:11940670
supporting_text: "Overexpression of the hASH1-dimerizing partner E12 could
protect hASH1 from degradation"
- molecular_function:
id: GO:0046983
label: protein dimerization activity
description: >-
ASCL1 forms heterodimers with E-proteins via its HLH domain, which is required
for DNA binding
and transcriptional function.
supported_by:
- reference_id: PMID:10903890
supporting_text: "E2-2 interacts with HASH-1 in both yeast and mammalian cells.
The HASH-1/E2-2 complex binds an E-box"
suggested_questions:
- question: What are the specific chromatin targets where ASCL1 acts as a
classical pioneer factor versus requiring mSWI/SNF cooperation?
- question: How does ASCL1 function as both activator and repressor depending
on target gene context?
- question: What determines whether ASCL1 homodimerizes versus heterodimerizes
with specific E-proteins?