RBFOX3 (RNA Binding Protein Fox-1 Homolog 3) is a neuronal-specific RNA-binding protein (~314 amino acids) that regulates alternative splicing in the central nervous system. Also known as NeuN (Neuronal nuclei antigen), it serves as a definitive marker for post-mitotic neurons and is critical for neuronal differentiation, adult neurogenesis, and synaptic function. Contains a highly conserved RNA recognition motif (RRM) that binds to UGCAUG sequences in pre-mRNA. Functions both as an activator and repressor of alternative splicing in a position-dependent manner. Alternative splicing produces nuclear (~46 kDa) and cytoplasmic (~48 kDa) isoforms with distinct functions. Essential for maintaining excitatory/inhibitory balance in neural circuits. RBFOX3 operates as part of the LASR (Large Assembly of Splicing Regulators) complex. Important splicing targets include Tau exon 10 (involved in tauopathy pathogenesis). Loss-of-function mutations in RBFOX3 are associated with rolandic epilepsy, and common variants are linked to sleep latency. Aberrant cytoplasmic mislocalization has been observed in HIV-associated neurocognitive disorders.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000381 regulation of alternative mRNA splicing, via spliceosome | IEA GO_REF:0000002 | ACCEPT | Summary: Automated annotation based on protein family membership Reason: Core function of RBFOX3 - well-documented regulation of alternative splicing through position-dependent binding to (U)GCAUG motifs Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research-falcon.md RBFOX3 is a member of the RBFOX family of splicing regulators that share a single central **RNA-recognition motif (RRM)** and preferentially bind the cis-element **(U)GCAUG**, using a **position-dependent** mechanism to activate or repress alternative exons. |
| GO:0003676 nucleic acid binding | IEA GO_REF:0000120 | MODIFY | Summary: Automated annotation based on RNA-binding domain Reason: Too general - RBFOX3 specifically binds RNA, not DNA. More specific RNA binding terms are available Proposed replacements: RNA binding |
| GO:0003723 RNA binding | IEA GO_REF:0000120 | ACCEPT | Summary: Automated annotation based on RNA recognition motif Reason: Accurate and well-supported - RBFOX3 contains RRM domain and binds specific RNA sequences (PMID:21747913, file:human/RBFOX3/RBFOX3-bioinformatics/rbfox3_analysis/RESULTS.md) Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research-falcon.md RBFOX3/NeuN is an RNA-binding protein that contains a **single central RRM/RBD** typical of RBFOX proteins, supporting its primary role as a sequence-specific regulator of RNA processing. |
| GO:0007399 nervous system development | IEA GO_REF:0000002 | ACCEPT | Summary: Automated and inferred annotation based on neuronal expression Reason: Well-supported - RBFOX3 is essential for neuronal differentiation and CNS development (PMID:23420872, file:human/RBFOX3/RBFOX3-deep-research.md) Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research-falcon.md RBFOX3 is implicated in neurogenesis and post-mitotic neuronal differentiation by controlling splicing choices in key developmental regulators |
| GO:0043484 regulation of RNA splicing | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: Automated annotation based on splicing regulator function Reason: Accurate but less specific than 'regulation of alternative mRNA splicing' - alternative splicing is RBFOX3's core function (PMID:21747913) |
| GO:0005634 nucleus | IEA GO_REF:0000120 | ACCEPT | Summary: Automated annotation and phylogenetic inference Reason: RBFOX3 nuclear isoforms are well-documented and functionally important (PMID:21747913). Nuclear localization is accurate for the relevant isoforms. Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research-falcon.md RBFOX3v2 is mainly nuclear and RBFOX3v3 is mainly cytoplasmic; the cytoplasmic isoform may still access the nucleus (potential shuttling), allowing it to regulate splicing. |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: Automated annotation and phylogenetic inference Reason: RBFOX3 cytoplasmic isoforms are well-documented with distinct functions (PMID:21747913). Cytoplasmic localization is accurate for the relevant isoforms. Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research-falcon.md Alternative splicing can generate isoforms with nuclear versus cytoplasmic distribution |
| GO:0006397 mRNA processing | IEA GO_REF:0000043 | MODIFY | Summary: Automated annotation based on RNA processing function Reason: Too general - RBFOX3 specifically regulates alternative splicing, not general mRNA processing (file:human/RBFOX3/RBFOX3-bioinformatics/rbfox3_analysis/RESULTS.md). Falcon deep research notes RBFOX3 does have a distinct non-splicing mRNA-related role in pri-miRNA processing, but its core pre-mRNA role is alternative splicing regulation. Proposed replacements: regulation of alternative mRNA splicing, via spliceosome Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research-falcon.md RBFOX3 regulates alternative splicing programs characteristic of neuronal differentiation and mature neuronal identity |
| GO:0008380 RNA splicing | IEA GO_REF:0000043 | MODIFY | Summary: Automated annotation based on splicing function Reason: Less specific than RBFOX3's actual function - it regulates alternative splicing, not general splicing (PMID:21747913) Proposed replacements: regulation of alternative mRNA splicing, via spliceosome Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research-falcon.md binding downstream of an alternative exon tends to enhance exon inclusion, whereas binding upstream tends to repress inclusion |
| GO:0003729 mRNA binding | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference based on ortholog functions Reason: Accurate and specific - RBFOX3 binds to specific mRNA sequences through its RRM domain (file:human/RBFOX3/RBFOX3-bioinformatics/rbfox3_analysis/RESULTS.md) Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research-falcon.md RBFOX family proteins (including RBFOX3) preferentially bind the canonical RNA element **(U)GCAUG** |
| GO:0005634 nucleus | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference of nuclear localization Reason: RBFOX3 nuclear isoforms are well-documented and functionally important (PMID:21747913) |
| GO:0007399 nervous system development | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference based on neuronal development role Reason: RBFOX3 is essential for neuronal differentiation and CNS development (file:human/RBFOX3/RBFOX3-deep-research.md) |
| GO:0000381 regulation of alternative mRNA splicing, via spliceosome | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference of alternative splicing regulation Reason: Core function - RBFOX3 regulates alternative splicing through position-dependent binding (PMID:21747913, file:human/RBFOX3/RBFOX3-deep-research.md) Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research-falcon.md RBFOX3 binds a **conserved upstream intronic UGCAUG element** near an alternative exon and represses its inclusion. In vivo and in-development loss-of-function experiments support that RBFOX3-dependent Numb splicing promotes neuronal differentiation. |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference of cytoplasmic localization Reason: RBFOX3 cytoplasmic isoforms are well-documented with distinct functions (PMID:21747913) |
| GO:0032228 regulation of synaptic transmission, GABAergic | ISS file:human/RBFOX3/RBFOX3-deep-research.md | NEW | Summary: RBFOX3 regulates GABAergic synaptic transmission through alternative splicing of GABAergic pathway genes, maintaining excitatory/inhibitory balance. Reason: Co-expression network analyses link RBFOX3 to GABAergic pathway genes. Loss of RBFOX3 disrupts excitatory/inhibitory balance in neural circuits. Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research.md co-expression network analyses in humans have linked RBFOX3 to genes involved in neurotransmitter release (including GABAergic pathways) |
| GO:0045773 positive regulation of axon extension | ISS file:human/RBFOX3/RBFOX3-deep-research.md | NEW | Summary: RBFOX3 promotes neurite outgrowth and axonal extension during neuronal differentiation. Reason: Knockdown of RBFOX3 impairs neurite outgrowth, while normal RBFOX3 expression promotes neuronal maturation including axon development. Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research.md Knockdown of RBFOX3 impairs neuron differentiation (e.g., reduced neurite outgrowth and delayed expression of neuronal markers) |
| GO:0048870 cell motility | ISS file:human/RBFOX3/RBFOX3-deep-research.md | NEW | Summary: RBFOX3 regulates neuronal migration through alternative splicing of cell motility genes including NUMB. Reason: RBFOX3-mediated splicing of NUMB affects cell fate decisions and neuronal migration during development. Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research.md alternative splicing of key developmental regulators like Numb, as well as other targets that influence cell fate decisions |
| GO:0005681 spliceosomal complex | IEA file:human/RBFOX3/RBFOX3-deep-research.md | NEW | Summary: RBFOX3 functions as part of large spliceosomal regulatory complexes Reason: RBFOX proteins assemble into the LASR (Large Assembly of Splicing Regulators) complex via their C-terminal domains, interacting with other splicing co-factors to regulate exon inclusion. This places RBFOX3 functionally within spliceosomal regulatory complexes. Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research.md RBFOX proteins are known to function as part of a large spliceosomal assembly (the Large Assembly of Splicing Regulators) via their C-termini, interacting with other splicing co-factors file:human/RBFOX3/RBFOX3-deep-research-falcon.md summarizes the position-dependent mechanism and network-level operation of RBFOX proteins (including LASR association and noncanonical recruitment) |
| GO:0005829 cytosol | IEA file:human/RBFOX3/RBFOX3-deep-research.md | NEW | Summary: Cytoplasmic isoform of RBFOX3 localizes to cytosol Reason: The larger 48 kDa RBFOX3 isoform is predominantly cytoplasmic, where it may regulate mRNA stability and nonsense-mediated decay. Alternative splicing produces both nuclear and cytoplasmic variants with distinct functions. Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research.md the ~46 kDa form is largely nuclear, whereas the slightly larger ~48 kDa isoform is found predominantly in the cytoplasm file:human/RBFOX3/RBFOX3-deep-research-falcon.md RBFOX3v2 is mainly nuclear and RBFOX3v3 is mainly cytoplasmic; the cytoplasmic isoform may still access the nucleus (potential shuttling), allowing it to regulate splicing. |
| GO:0043025 neuronal cell body | IEA file:human/RBFOX3/RBFOX3-deep-research.md | NEW | Summary: RBFOX3/NeuN is concentrated in neuronal cell bodies Reason: Immunostaining with NeuN antibody shows strong labeling in neuronal nuclei and perikarya (cell bodies). RBFOX3 is present throughout the neuronal cell body with nuclear concentration, making it a definitive marker for neuronal soma. Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research.md RBFOX3 concentrates in the neuronal nucleus (often excluding the nucleolus) and can also be detected in perikarya – reflecting its presence in the neuronal cell body file:human/RBFOX3/RBFOX3-deep-research-falcon.md RBFOX3 is largely neuron-restricted, whereas RBFOX1 is expressed in neurons as well as muscle/heart and RBFOX2 has broader expression across tissues/cell types. |
| GO:0045666 positive regulation of neuron differentiation | IEA file:human/RBFOX3/RBFOX3-deep-research.md | NEW | Summary: RBFOX3 drives neuronal maturation and differentiation Reason: Loss-of-function studies demonstrate RBFOX3 is essential for neuronal differentiation. Knockdown impairs neurite outgrowth and delays neuronal marker expression, while normal RBFOX3 promotes the transition of immature neurons to fully differentiated states through alternative splicing of developmental regulators like Numb. Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research.md Knockdown of RBFOX3 impairs neuron differentiation (e.g., reduced neurite outgrowth and delayed expression of neuronal markers), whereas normal RBFOX3 promotes the transition of immature neurons into fully differentiated states file:human/RBFOX3/RBFOX3-deep-research-falcon.md RBFOX3 binds a **conserved upstream intronic UGCAUG element** near an alternative exon and represses its inclusion. In vivo and in-development loss-of-function experiments support that RBFOX3-dependent Numb splicing promotes neuronal differentiation. |
| GO:0048167 regulation of synaptic plasticity | IEA file:human/RBFOX3/RBFOX3-deep-research.md | NEW | Summary: RBFOX3 regulates synaptic plasticity in hippocampal circuits Reason: RBFOX3 knockout mice show defects in long-term synaptic plasticity (LTP/LTD) and altered neurotransmitter release probability. RBFOX3 controls splicing of ion channels, neurotransmitter receptors, and synaptic proteins that govern neurotransmission and plasticity. Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research.md RBFOX3 knockout leads to altered expression of synapse-related gene isoforms, a decrease in long-term synaptic plasticity, and an increase in dendritic spine density |
| GO:0050769 positive regulation of neurogenesis | IEA file:human/RBFOX3/RBFOX3-deep-research.md | NEW | Summary: RBFOX3 promotes adult hippocampal neurogenesis Reason: Mice lacking RBFOX3 show deficits in adult hippocampal neurogenesis, with reduced proliferation or survival of newborn neurons in the dentate gyrus. RBFOX3 is required for proper generation and integration of new neurons in the adult brain. Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research.md Mice lacking RBFOX3 show deficits in adult hippocampal neurogenesis, evidenced by reduced proliferation or survival of newborn neurons in the dentate gyrus file:human/RBFOX3/RBFOX3-deep-research-falcon.md RBFOX3 is implicated in neurogenesis and post-mitotic neuronal differentiation by controlling splicing choices in key developmental regulators |
| GO:0050804 modulation of chemical synaptic transmission | IEA file:human/RBFOX3/RBFOX3-deep-research.md | NEW | Summary: RBFOX3 modulates synaptic transmission and neurotransmitter release Reason: RBFOX3-null mice exhibit defective synaptic transmission with increased frequency of spontaneous excitatory events and elevated neurotransmitter release probability. RBFOX3 maintains excitatory/inhibitory balance through splicing control of synaptic proteins. Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research.md Electrophysiological studies in RBFOX3-null mice reveal defective synaptic transmission and an increased frequency of spontaneous excitatory events, associated with an elevated neurotransmitter release probability |
| GO:0050808 synapse organization | IEA file:human/RBFOX3/RBFOX3-deep-research.md | NEW | Summary: RBFOX3 regulates synaptogenesis and synaptic structure Reason: RBFOX3 knockout mice show abnormalities in synaptogenesis with increased dendritic spine density indicative of aberrant synapse formation. RBFOX3 controls alternative splicing of synapse-related gene isoforms essential for proper synapse organization. Supporting Evidence: file:human/RBFOX3/RBFOX3-deep-research.md RBFOX3 knockout leads to altered expression of synapse-related gene isoforms, a decrease in long-term synaptic plasticity, and an increase in dendritic spine density (indicative of aberrant synapse formation) |
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Download this section (compressed HTML)Q: How do the nuclear and cytoplasmic isoforms of RBFOX3 coordinate to regulate both alternative splicing and mRNA localization in post-mitotic neurons?
Q: What determines the specificity of RBFOX3 binding to UGCAUG motifs and how does binding position relative to exons influence splicing outcomes?
Q: How does RBFOX3 expression and activity change during neuronal differentiation and maturation, and what role does this play in establishing neuronal identity?
Q: What are the mechanisms by which RBFOX3 maintains the balance between excitatory and inhibitory neurotransmission at the molecular level?
Experiment: Single-cell RNA sequencing combined with RBFOX3 ChIP-seq to map tissue-specific and cell-type-specific alternative splicing programs in different brain regions
Experiment: Super-resolution microscopy to visualize the subcellular localization and dynamics of RBFOX3 isoforms during neuronal activity and synaptic plasticity
Experiment: CRISPR-Cas13 mediated knockdown of specific RBFOX3 isoforms to dissect their individual contributions to neuronal function and splicing regulation
Experiment: Proteomics analysis using proximity labeling to identify RBFOX3 interacting partners in nuclear versus cytoplasmic compartments during neuronal development
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Download this section (compressed HTML)📊 View Pathway Visualization Interactive pathway diagram with detailed annotations