AVEN is an anti-apoptotic regulator that inhibits the intrinsic apoptosis pathway through two complementary mechanisms. First, it binds Apaf-1 and interferes with Apaf-1 self-association, thereby blocking apoptosome assembly and caspase-9 activation. Second, it binds and stabilizes the anti-apoptotic BCL-xL protein, potentiating its pro-survival function. AVEN contains a predicted BH3-like motif (aa 141-153) that mediates BCL-xL interaction. The full anti-apoptotic potential of AVEN is unleashed by cathepsin D cleavage that removes an inhibitory N-terminal domain. AVEN also participates in the DNA damage response, where ATM phosphorylates it at Ser135/Ser138 to promote G2/M checkpoint arrest. AVEN is overexpressed in hematologic malignancies and contributes to chemotherapy resistance.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0010972
negative regulation of G2/M transition of mitotic cell cycle
|
IBA
GO_REF:0000033 |
KEEP AS NON CORE |
Summary: AVEN participates in the DNA damage response and promotes G2/M checkpoint arrest. ATM phosphorylates AVEN at Ser135 and Ser138 upon DNA damage, and these phosphorylation sites are required for AVEN-driven checkpoint function. This IBA annotation is phylogenetically inferred and is consistent with experimental evidence showing AVEN's role in DNA damage checkpoint signaling.
Reason: While AVEN does contribute to G2/M checkpoint arrest via ATM-dependent phosphorylation, this represents a secondary/modulatory function rather than AVEN's core anti-apoptotic role. The primary function of AVEN is inhibition of apoptosome assembly and BCL-xL stabilization. The checkpoint function is mechanistically distinct and should be retained as a non-core annotation.
Supporting Evidence:
file:human/AVEN/AVEN-deep-research-falcon.md
ATM phosphorylates Aven at Ser135 and Ser138, and these sites are required for Aven-driven checkpoint function
|
|
GO:0006915
apoptotic process
|
IEA
GO_REF:0000043 |
MODIFY |
Summary: This IEA annotation is based on the UniProt keyword 'Apoptosis'. AVEN is indeed involved in apoptosis, but as a negative regulator. The term 'apoptotic process' is too general and does not capture AVEN's specific anti-apoptotic function. AVEN inhibits the intrinsic apoptosis pathway by binding Apaf-1 and preventing apoptosome assembly, and by stabilizing BCL-xL.
Reason: The annotation is not wrong (AVEN is involved in the apoptotic process), but it lacks specificity. AVEN specifically negatively regulates apoptosis through direct inhibition of apoptosome assembly and BCL-xL stabilization. A more informative annotation would be 'negative regulation of apoptotic process' (GO:0043066), which is already annotated with IDA evidence.
Proposed replacements:
negative regulation of apoptotic process
Supporting Evidence:
PMID:10949025
Aven interferes with the ability of Apaf-1 to self-associate, suggesting that Aven impairs Apaf-1-mediated activation of caspases. Consistent with this idea, Aven inhibited the proteolytic activation of caspases in a cell-free extract and suppressed apoptosis induced by Apaf-1 plus caspase-9.
|
|
GO:0012505
endomembrane system
|
IEA
GO_REF:0000044 |
ACCEPT |
Summary: This IEA annotation is based on UniProt subcellular location mapping. UniProt states AVEN is "Associated with intracellular membranes" and is a peripheral membrane protein of the endomembrane system. The original Chau et al. 2000 paper showed AVEN localizes to light membrane/vesicular fractions with diffuse nuclear and reticular cytoplasmic staining. Later work showed AVEN co-localizes with cathepsin D in vesicular compartments.
Reason: The annotation is consistent with experimental evidence showing AVEN association with intracellular membranes and vesicular compartments. This localization is functionally relevant as cathepsin D processing of AVEN in vesicular compartments releases its anti-apoptotic potential.
Supporting Evidence:
PMID:10949025
Aven, a novel inhibitor of caspase activation, binds Bcl-xL and Apaf-1
file:human/AVEN/AVEN-deep-research-falcon.md
Aven localizes mainly to light membrane/vesicular fractions, with diffuse nuclear and reticular cytoplasmic staining; it can co-localize with cathepsin D (CathD) in vesicular compartments
|
|
GO:0005515
protein binding
|
IPI
PMID:10949025 Aven, a novel inhibitor of caspase activation, binds Bcl-xL ... |
REMOVE |
Summary: This annotation reflects AVEN's binding to APAF1 (O14727) and BCL2L1/BCL-xL (Q07817). While the interactions are well-documented (AVEN was discovered through yeast two-hybrid screen for BCL-xL interactors), the term 'protein binding' is uninformative. More specific molecular function terms should be used.
Reason: The term 'protein binding' (GO:0005515) is too generic to be informative. AVEN has specific, characterized binding partners (Apaf-1 and BCL-xL) with defined functional consequences. The binding to Apaf-1 inhibits apoptosome assembly, while BCL-xL binding stabilizes and potentiates this anti-apoptotic protein. More specific terms like 'BH domain binding' (GO:0051400) for BCL-xL interaction would be more appropriate, though the core function is better captured by process annotations.
Supporting Evidence:
PMID:10949025
Aven is broadly expressed and is conserved in other mammalian species. Only those mutants of Bcl-x(L)that retain their antiapoptotic activity are capable of binding Aven.
|
|
GO:0005829
cytosol
|
TAS
Reactome:R-HSA-6805507 |
ACCEPT |
Summary: This TAS annotation from Reactome reflects AVEN localization in the cytosol where it can interact with Apaf-1 to inhibit apoptosome assembly. Apoptosome formation occurs in the cytosol following cytochrome c release from mitochondria, so cytosolic localization of AVEN is required for its anti-apoptotic function.
Reason: Cytosolic localization is consistent with AVEN's function as an inhibitor of apoptosome assembly. The Reactome pathway 'APAF1 binds AVEN' documents this interaction in the cytosol. AVEN also associates with membrane fractions, but cytosolic AVEN is the pool that interacts with Apaf-1 to prevent caspase activation.
Supporting Evidence:
Reactome:R-HSA-6805507
The binding of AVEN to apoptotic protease activating factor 1 (APAF1) is thought to interfere with the ability of APAF1 to self-associate during apoptosome assembly
|
|
GO:0016020
membrane
|
IDA
PMID:10949025 Aven, a novel inhibitor of caspase activation, binds Bcl-xL ... |
ACCEPT |
Summary: This IDA annotation indicates AVEN associates with membranes. The original Chau et al. paper showed AVEN localizes to light membrane fractions by subcellular fractionation. UniProt describes AVEN as a peripheral membrane protein of the endomembrane system.
Reason: The membrane localization is experimentally validated and functionally relevant. AVEN co-localizes with cathepsin D in vesicular/membrane compartments where proteolytic processing removes the N-terminal inhibitory domain to unleash AVEN's full anti-apoptotic activity. Both cytosolic and membrane-associated pools of AVEN are physiologically relevant.
Supporting Evidence:
PMID:10949025
Aven, a novel inhibitor of caspase activation, binds Bcl-xL and Apaf-1
file:human/AVEN/AVEN-deep-research-falcon.md
Biochemical fractionation and microscopy place Aven in light membrane/vesicular pools and nucleus/cytoplasm
|
|
GO:0043066
negative regulation of apoptotic process
|
IDA
PMID:10949025 Aven, a novel inhibitor of caspase activation, binds Bcl-xL ... |
ACCEPT |
Summary: This is the core functional annotation for AVEN. AVEN negatively regulates apoptosis through two mechanisms: (1) binding Apaf-1 and interfering with its self-association, thereby blocking apoptosome assembly and caspase-9 activation; (2) binding and stabilizing BCL-xL to potentiate its anti-apoptotic function. Chau et al. demonstrated that AVEN inhibited caspase proteolytic activation in cell-free extracts and suppressed apoptosis induced by Apaf-1 plus caspase-9. AVEN also protected against death in a mouse Sindbis virus infection model.
Reason: This annotation accurately captures AVEN's core function as an anti-apoptotic regulator. The IDA evidence from the original discovery paper is strong, demonstrating both biochemical inhibition of caspase activation and cellular protection from apoptosis. This is a legitimate, evolved anti-apoptotic function, not a downstream metabolic effect.
Supporting Evidence:
PMID:10949025
Aven interferes with the ability of Apaf-1 to self-associate, suggesting that Aven impairs Apaf-1-mediated activation of caspases. Consistent with this idea, Aven inhibited the proteolytic activation of caspases in a cell-free extract and suppressed apoptosis induced by Apaf-1 plus caspase-9.
|
|
GO:1905101
negative regulation of apoptosome assembly
|
IDA
PMID:10949025 Aven, a novel inhibitor of caspase activation, binds Bcl-xL ... |
NEW |
Summary: AVEN directly inhibits apoptosome assembly by binding Apaf-1 and preventing its self-association. This is the specific mechanistic step at which AVEN acts to inhibit apoptosis.
Reason: This term (GO:1905101) more precisely describes AVEN's mechanism of action than the broader 'negative regulation of apoptotic process'. AVEN binds Apaf-1 and interferes with its oligomerization, which is required for apoptosome formation. This is the proximal step that AVEN inhibits to block caspase activation.
Supporting Evidence:
PMID:10949025
Aven interferes with the ability of Apaf-1 to self-associate, suggesting that Aven impairs Apaf-1-mediated activation of caspases.
Reactome:R-HSA-6805507
The binding of AVEN to apoptotic protease activating factor 1 (APAF1) is thought to interfere with the ability of APAF1 to self-associate during apoptosome assembly
|
|
GO:0051400
BH domain binding
|
IDA
PMID:10949025 Aven, a novel inhibitor of caspase activation, binds Bcl-xL ... |
NEW |
Summary: AVEN binds BCL-xL (BCL2L1), an anti-apoptotic BCL-2 family member. AVEN was originally identified by yeast two-hybrid screen for BCL-xL interactors. Computational analysis has identified a predicted BH3-like motif in AVEN (aa 141-153) that may mediate this interaction. Only BCL-xL mutants that retain anti-apoptotic activity can bind AVEN.
Reason: This molecular function annotation would capture AVEN's specific interaction with BCL-xL through the BH domain binding interface. This is more informative than generic 'protein binding' and reflects the BH3-like motif in AVEN that mediates the interaction.
Supporting Evidence:
PMID:10949025
Only those mutants of Bcl-x(L)that retain their antiapoptotic activity are capable of binding Aven.
file:human/AVEN/AVEN-deep-research-falcon.md
Computational/biophysical analyses identified a BH3-like segment in Aven (aa 141-153) predicted to bind BCL-xL with appreciable affinity
|
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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 'AVEN' 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 AVEN (gene ID: AVEN, UniProt: Q9NQS1) 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 'AVEN' 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 AVEN (gene ID: AVEN, UniProt: Q9NQS1) 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.
Research plan and verification
- Identity verification: The target is the human gene AVEN (UniProt: Q9NQS1), encoding “cell death regulator Aven” (also called AVEN). Foundational papers identify human Aven as a novel anti-apoptotic factor that binds BCL-xL (BCL2L1) and Apaf-1, and inhibits caspase activation in human systems, confirming the gene/protein match and organism (Homo sapiens) (chau2000avenanovel pages 1-2, chau2000avenanovel pages 2-3).
- Scope of this report: mechanistic function, interaction partners, subcellular localization, pathway placement, disease links, and translational context, with URLs and publication years for each cited source.
1) Key concepts and definitions
- Definition and discovery: Aven is an anti-apoptotic protein first identified by yeast two-hybrid screening for interactors of BCL-xL; it also binds Apaf-1 and can block Apaf-1 self-association, thereby inhibiting apoptosome formation and caspase-9 activation downstream of mitochondrial cytochrome c release (intrinsic apoptosis) (Molecular Cell, 2000; https://doi.org/10.1016/S1097-2765(05)00021-3) (chau2000avenanovel pages 1-2, chau2000avenanovel pages 2-3).
- Mechanistic role: Aven prevents Apaf-1-driven apoptosome assembly/activation and can stabilize the pro-survival Bcl-2 family protein BCL-xL, collectively dampening caspase activation and apoptosis signals (Eur J Cancer, 2010; https://doi.org/10.1016/j.ejca.2010.06.011; Cell Death Differ, 2012; https://doi.org/10.1038/cdd.2012.17) (kutuk2010avenblocksdna pages 1-2, melzer2012theapaf1bindingprotein pages 1-2).
- Cellular distribution: Aven localizes mainly to light membrane/vesicular fractions, with diffuse nuclear and reticular cytoplasmic staining; it can co-localize with cathepsin D (CathD) in vesicular compartments, consistent with proteolytic processing in endolysosomal-derived environments (Molecular Cell, 2000; Cell Death Differ, 2012) (https://doi.org/10.1016/S1097-2765(05)00021-3; https://doi.org/10.1038/cdd.2012.17) (chau2000avenanovel pages 1-2, melzer2012theapaf1bindingprotein pages 1-2).
2) Mechanisms, interactions, and structural/biochemical details
- Apaf-1 interaction and apoptosome inhibition: Aven binds Apaf-1 at/near regions encompassing the CARD-containing portion of Apaf-1 and impairs Apaf-1 self-association, inhibiting Apaf-1–mediated caspase activation in cell-free systems and in cells (Molecular Cell, 2000; Cell Death Differ, 2012) (https://doi.org/10.1016/S1097-2765(05)00021-3; https://doi.org/10.1038/cdd.2012.17) (chau2000avenanovel pages 8-9, chau2000avenanovel pages 1-2, melzer2012theapaf1bindingprotein pages 1-2).
- BCL-xL interaction and stabilization: Aven forms complexes with BCL-xL in untreated breast cancer cells. Enforced Aven expression protects against UV-, SN-38–, and cisplatin-induced apoptosis, whereas Aven knockdown enhances apoptosis. Critically, loss of BCL-xL abrogates Aven’s protection, indicating Aven’s pro-survival function requires BCL-xL; Aven acts in part by stabilizing BCL-xL (Eur J Cancer, 2010; https://doi.org/10.1016/j.ejca.2010.06.011) (kutuk2010avenblocksdna pages 1-2).
- N-terminal inhibitory domain and cathepsin D activation: Aven harbors an N-terminal inhibitory segment whose proteolytic removal “unleashes” anti-apoptotic activity. Cathepsin D cleaves human Aven in vitro at mapped sites around amino acids ~144/145 and ~196/197; N-terminally truncated Aven retains Apaf-1 binding but exhibits enhanced anti-apoptotic function. Aven co-localizes with CathD in vesicular compartments, supporting physiological processing (Cell Death Differ, 2012; https://doi.org/10.1038/cdd.2012.17) (melzer2012theapaf1bindingprotein pages 1-2, melzer2012theapaf1bindingprotein pages 7-8).
- Putative BH3-like element and binding model: Computational/biophysical analyses identified a BH3-like segment in Aven (aa 141–153) predicted to bind BCL-xL with appreciable affinity, rationalizing the original yeast two-hybrid result and selective binding to anti-apoptotic Bcl-2 proteins (Open Biology Journal, 2012; https://doi.org/10.2174/1874196701205010006) (hawley2012anintegratedbioinformatics pages 4-5).
- DNA damage and checkpoint signaling: Aven contributes to the DNA damage response, promoting ATM-dependent G2/M checkpoint arrest; ATM phosphorylates Aven at Ser135 and Ser138, and these sites are required for Aven-driven checkpoint function (Eur J Cancer, 2010; https://doi.org/10.1016/j.ejca.2010.06.011; Open Biology Journal, 2012; https://doi.org/10.2174/1874196701205010006) (kutuk2010avenblocksdna pages 1-2, hawley2012anintegratedbioinformatics pages 4-5).
3) Pathway and subcellular context
- Pathway placement: Aven functions within the intrinsic apoptosis pathway at a post-mitochondrial checkpoint by directly inhibiting Apaf-1/apoptosome formation and by bolstering BCL-xL function, thereby reducing caspase-9 activation and executioner caspase processing (Molecular Cell, 2000; Cell Death Differ, 2012) (https://doi.org/10.1016/S1097-2765(05)00021-3; https://doi.org/10.1038/cdd.2012.17) (chau2000avenanovel pages 1-2, melzer2012theapaf1bindingprotein pages 1-2).
- Localization: Biochemical fractionation and microscopy place Aven in light membrane/vesicular pools and nucleus/cytoplasm; co-localization with CathD suggests endolysosomal/vesicular processing contributes to functional regulation (Molecular Cell, 2000; Cell Death Differ, 2012) (https://doi.org/10.1016/S1097-2765(05)00021-3; https://doi.org/10.1038/cdd.2012.17) (chau2000avenanovel pages 1-2, melzer2012theapaf1bindingprotein pages 1-2).
4) Disease associations and translational relevance
- Hematologic malignancy: AVEN is overexpressed in acute leukemias, correlating with adverse outcomes (e.g., poor prognosis in childhood ALL). In T-cell–specific transgenic models, AVEN overexpression cooperates with p53 haploinsufficiency to accelerate T-cell lymphomagenesis. In human leukemia lines (MOLT-4, CCRF-CEM, Kasumi-1), AVEN knockdown increases apoptosis and limits growth, supporting an oncoprotein role (Oncogene, 2013; https://doi.org/10.1038/onc.2012.263) (eissmann2013overexpressionofthe pages 1-2).
- Solid tumors and chemotherapy response: In breast cancer models, Aven promotes survival after DNA damage by stabilizing BCL-xL; Aven depletion sensitizes cells to DNA-damaging agents (Eur J Cancer, 2010; https://doi.org/10.1016/j.ejca.2010.06.011) (kutuk2010avenblocksdna pages 1-2).
- In vivo antiviral/apoptosis model: Human Aven reduced organismal death in a mouse Sindbis virus infection model, illustrating potent anti-apoptotic function in vivo (Molecular Cell, 2000; https://doi.org/10.1016/S1097-2765(05)00021-3) (chau2000avenanovel pages 2-3).
5) Quantitative and experimental highlights
- Interaction and function assays: Aven–BCL-xL and Aven–Apaf-1 interactions were shown by yeast two-hybrid and co-immunoprecipitation. Functional inhibition of the apoptosome was demonstrated in cell-free reconstitutions and in cells, with reduced caspase-9/-3 activation. Tissue fractionation and confocal microscopy delineated subcellular pools (Molecular Cell, 2000; https://doi.org/10.1016/S1097-2765(05)00021-3) (chau2000avenanovel pages 1-2).
- Cathepsin D processing sites: In vitro mapping implicated cleavage near aa 144/145 and 196/197. N-terminally truncated Aven (ΔN-Aven) retains Apaf-1 binding with enhanced anti-apoptotic effect, supporting a protease-activation switch (Cell Death Differ, 2012; https://doi.org/10.1038/cdd.2012.17) (melzer2012theapaf1bindingprotein pages 7-8).
- Dependency on BCL-xL: In breast cancer cells, Aven’s cytoprotection against DNA damage required BCL-xL; siRNA depletion of BCL-xL negated Aven’s protective effect (Eur J Cancer, 2010; https://doi.org/10.1016/j.ejca.2010.06.011) (kutuk2010avenblocksdna pages 1-2).
- Expression breadth: Northern blotting detected an ~1.7 kb AVEN transcript broadly in adult human tissues, with notable expression in heart, skeletal muscle, kidney, liver, pancreas, and testis (Molecular Cell, 2000; https://doi.org/10.1016/S1097-2765(05)00021-3) (chau2000avenanovel pages 2-3).
6) Recent developments (2023–2024)
- Targeted 2023–2024 literature searches did not retrieve AVEN-specific primary studies or authoritative reviews with novel mechanistic updates beyond the established interaction with BCL-xL/Apaf-1, CathD-mediated activation, and oncogenic roles summarized above. Current translational activity around intrinsic apoptosis more broadly (e.g., BCL-xL pharmacology) remains active, but AVEN-focused advances in 2023–2024 were not identified in our evidence set. This highlights a potential evidence gap and opportunity for updated functional/structural studies of AVEN in human disease contexts (kutuk2010avenblocksdna pages 1-2).
7) Expert perspectives and open questions
- The foundational and mechanistic studies collectively support AVEN as a node at the apoptosome checkpoint and a BCL-xL-cooperative survival factor. Key open questions include: structural resolution of the Aven–Apaf-1 interface; definitive mapping of domains/motifs governing BCL-xL binding in full-length Aven; the extent of protease-mediated activation in vivo across tumor types; and whether AVEN status can stratify response to DNA-damaging therapy or BCL-xL–targeted approaches (Molecular Cell, 2000; Eur J Cancer, 2010; Cell Death Differ, 2012) (chau2000avenanovel pages 1-2, kutuk2010avenblocksdna pages 1-2, melzer2012theapaf1bindingprotein pages 1-2).
Embedded evidence summary
| Aspect | Key finding | Experimental evidence / assay | Model / system | URL | Year | Citation ID |
|---|---|---|---|---|---:|---|
| Discovery and identity | AVEN identified as a novel inhibitor of caspase activation that binds BCL-xL and APAF-1; broadly expressed transcript (~1.7 kb). | Yeast two-hybrid discovery, co-immunoprecipitation, cell-free apoptosome inhibition assays, in vivo protection (Sindbis virus mouse model). | Human cDNAs, transfected BHK cells, cell-free extracts, mouse infection model. | https://doi.org/10.1016/s1097-2765(05)00021-3 | 2000 | (chau2000avenanovel pages 2-3) |
| Binding to BCL-xL | AVEN binds anti-apoptotic BCL-xL; contains a BH3-like region predicted to mediate binding. | Yeast two-hybrid, co-IP, peptide modeling and binding assays; functional dependency shown by loss-of-function experiments. | Human cell lines, peptide assays, computational modeling. | https://doi.org/10.1016/s1097-2765(05)00021-3 , https://doi.org/10.1016/j.ejca.2010.06.011 | 2000, 2010 | (chau2000avenanovel pages 2-3, kutuk2010avenblocksdna pages 1-2) |
| Binding to APAF-1 and apoptosome inhibition | AVEN binds APAF-1 and interferes with APAF-1 self-association, inhibiting apoptosome formation and downstream caspase-9/-3 activation. | Co-immunoprecipitation, cell-free apoptosome reconstitution and caspase activity assays. | Cell-free extracts, human cells. | https://doi.org/10.1016/s1097-2765(05)00021-3 , https://doi.org/10.1038/cdd.2012.17 | 2000, 2012 | (chau2000avenanovel pages 2-3, melzer2012theapaf1bindingprotein pages 1-2) |
| Subcellular localization | Predominantly in light-membrane/vesicular fractions; shows diffuse nuclear and reticular cytoplasmic staining; colocalizes with Cathepsin D in vesicular compartments. | Subcellular fractionation, immunofluorescence/confocal microscopy, co-localization studies. | Transfected BHK cells, MCF-7 breast cancer cells. | https://doi.org/10.1016/s1097-2765(05)00021-3 , https://doi.org/10.1038/cdd.2012.17 | 2000, 2012 | (chau2000avenanovel pages 2-3, melzer2012theapaf1bindingprotein pages 1-2) |
| Stabilization of BCL-xL & effect on DNA-damage apoptosis | AVEN stabilizes BCL-xL and protects cells from DNA-damage–induced apoptosis; BCL-xL is required for AVEN's prosurvival effect (BCL-xL depletion abrogates protection). | Overexpression and RNAi knockdown, Annexin V, DEVDase/caspase activity assays, tissue microarray analysis. | Human breast cancer cell lines (e.g., MCF-7); clinical tissue arrays. | https://doi.org/10.1016/j.ejca.2010.06.011 | 2010 | (kutuk2010avenblocksdna pages 1-2) |
| ATM-related phosphorylation notes | AVEN participates in DNA-damage response: ATM phosphorylates AVEN (Ser135/Ser138), required for G2/M checkpoint function. | Phosphorylation assays, checkpoint assays, mutational analysis of phosphorylation sites. | Human cell lines subjected to DNA damage. | https://doi.org/10.1016/j.ejca.2010.06.011 , https://doi.org/10.2174/1874196701205010006 | 2010, 2012 | (kutuk2010avenblocksdna pages 1-2, hawley2012anintegratedbioinformatics pages 4-5) |
| Cathepsin D cleavage sites & activation of anti-apoptotic function | Cathepsin D (CathD) cleaves AVEN N-terminus (mapped in vitro to ~aa144/145 and aa196/197); N-terminal removal "unleashes" AVEN's anti-apoptotic activity while truncated AVEN still binds APAF-1. | In vitro CathD cleavage assays, western blot mapping of cleavage, co-IP of truncated constructs, colocalization with CathD. | Human cancer cell lines (e.g., MCF-7), biochemical assays. | https://doi.org/10.1038/cdd.2012.17 | 2012 | (melzer2012theapaf1bindingprotein pages 1-2) |
| Oncogenic overexpression in hematologic malignancies & functional effects | AVEN is overexpressed in acute leukemias (correlates with poor prognosis); AVEN overexpression promotes lymphomagenesis in transgenic mice (cooperates with p53 loss); AVEN knockdown reduces leukemia cell growth via apoptosis. | Patient mRNA expression profiling, transgenic mouse models, xenografts, RNAi-mediated knockdown, proliferation/apoptosis assays. | Human T-ALL patient samples, transgenic mice, human leukemia cell lines (MOLT-4, CCRF-CEM, Kasumi-1). | https://doi.org/10.1038/onc.2012.263 | 2013 | (eissmann2013overexpressionofthe pages 1-2) |
Table: Concise, source-linked experimental evidence summary for human AVEN (Q9NQS1), listing key functional findings, assays, models, exact URLs, years, and internal citation IDs to support functional annotation and translational context.
Conclusions
- Human AVEN (Q9NQS1) is a non-enzymatic anti-apoptotic regulator that binds BCL-xL and Apaf-1, inhibits apoptosome formation and caspase activation, and promotes cell survival after genotoxic stress, at least partly by stabilizing BCL-xL. Its anti-apoptotic potential is enhanced by N‑terminal removal via cathepsin D. AVEN is broadly expressed and is overexpressed in leukemias with functional oncogenic effects in vivo and in cell models, highlighting biomarker and therapeutic relevance. While the core biology is well established, recent AVEN-specific updates (2023–2024) appear limited in the retrieved literature, underscoring a need for renewed investigation into its structure–function relationships and translational exploitation (chau2000avenanovel pages 1-2, chau2000avenanovel pages 2-3, kutuk2010avenblocksdna pages 1-2, melzer2012theapaf1bindingprotein pages 1-2, eissmann2013overexpressionofthe pages 1-2).
References
(chau2000avenanovel pages 1-2): BN Chau, EHY Cheng, DA Kerr, and JM Hardwick. Aven, a novel inhibitor of caspase activation, binds bcl-xl and apaf-1. Molecular cell, 6 1:31-40, Jul 2000. URL: https://doi.org/10.1016/s1097-2765(05)00021-3, doi:10.1016/s1097-2765(05)00021-3. This article has 305 citations and is from a highest quality peer-reviewed journal.
(chau2000avenanovel pages 2-3): BN Chau, EHY Cheng, DA Kerr, and JM Hardwick. Aven, a novel inhibitor of caspase activation, binds bcl-xl and apaf-1. Molecular cell, 6 1:31-40, Jul 2000. URL: https://doi.org/10.1016/s1097-2765(05)00021-3, doi:10.1016/s1097-2765(05)00021-3. This article has 305 citations and is from a highest quality peer-reviewed journal.
(kutuk2010avenblocksdna pages 1-2): Ozgur Kutuk, Sehime Gulsun Temel, Sahsine Tolunay, and Huveyda Basaga. Aven blocks dna damage-induced apoptosis by stabilising bcl-xl. European journal of cancer, 46 13:2494-505, Sep 2010. URL: https://doi.org/10.1016/j.ejca.2010.06.011, doi:10.1016/j.ejca.2010.06.011. This article has 55 citations and is from a domain leading peer-reviewed journal.
(melzer2012theapaf1bindingprotein pages 1-2): I. Melzer, Sbm Fernández, S. Bösser, K. Lohrig, U. Lewandrowski, D. Wolters, S. Kehrloesser, Marie-Luise Brezniceanu, Alexander C. Theos, PM Irusta, Francis Impens, K. Gevaert, and M. Zörnig. The apaf-1-binding protein aven is cleaved by cathepsin d to unleash its anti-apoptotic potential. Cell Death and Differentiation, 19:1435-1445, Mar 2012. URL: https://doi.org/10.1038/cdd.2012.17, doi:10.1038/cdd.2012.17. This article has 39 citations and is from a domain leading peer-reviewed journal.
(chau2000avenanovel pages 8-9): BN Chau, EHY Cheng, DA Kerr, and JM Hardwick. Aven, a novel inhibitor of caspase activation, binds bcl-xl and apaf-1. Molecular cell, 6 1:31-40, Jul 2000. URL: https://doi.org/10.1016/s1097-2765(05)00021-3, doi:10.1016/s1097-2765(05)00021-3. This article has 305 citations and is from a highest quality peer-reviewed journal.
(melzer2012theapaf1bindingprotein pages 7-8): I. Melzer, Sbm Fernández, S. Bösser, K. Lohrig, U. Lewandrowski, D. Wolters, S. Kehrloesser, Marie-Luise Brezniceanu, Alexander C. Theos, PM Irusta, Francis Impens, K. Gevaert, and M. Zörnig. The apaf-1-binding protein aven is cleaved by cathepsin d to unleash its anti-apoptotic potential. Cell Death and Differentiation, 19:1435-1445, Mar 2012. URL: https://doi.org/10.1038/cdd.2012.17, doi:10.1038/cdd.2012.17. This article has 39 citations and is from a domain leading peer-reviewed journal.
(hawley2012anintegratedbioinformatics pages 4-5): Robert G. Hawley, Yuzhong Chen, Irene Riz, and Chen Zeng. An integrated bioinformatics and computational biology approach identifies new bh3-only protein candidates. The open biology journal, 5:6-16, May 2012. URL: https://doi.org/10.2174/1874196701205010006, doi:10.2174/1874196701205010006. This article has 22 citations.
(eissmann2013overexpressionofthe pages 1-2): M. Eissmann, I. Melzer, S. B. M. Fernández, G. Michel, M. H. Angelis, G. Hoefler, P. Finkenwirth, A. Jauch, B. Schoell, M. Grez, M. Schmidt, C. Bartholomae, S. Newrzela, Nadine Haetscher, M. Rieger, C. Zachskorn, M. Mittelbronn, and M. Zörnig. Overexpression of the anti-apoptotic protein aven contributes to increased malignancy in hematopoietic neoplasms. Oncogene, 32:2586-2591, May 2013. URL: https://doi.org/10.1038/onc.2012.263, doi:10.1038/onc.2012.263. This article has 33 citations and is from a domain leading peer-reviewed journal.
id: Q9NQS1
gene_symbol: AVEN
product_type: PROTEIN
status: COMPLETE
taxon:
id: NCBITaxon:9606
label: Homo sapiens
description: >-
AVEN is an anti-apoptotic regulator that inhibits the intrinsic apoptosis pathway through two
complementary mechanisms. First, it binds Apaf-1 and interferes with Apaf-1 self-association,
thereby blocking apoptosome assembly and caspase-9 activation. Second, it binds and stabilizes
the anti-apoptotic BCL-xL protein, potentiating its pro-survival function. AVEN contains a
predicted BH3-like motif (aa 141-153) that mediates BCL-xL interaction. The full anti-apoptotic
potential of AVEN is unleashed by cathepsin D cleavage that removes an inhibitory N-terminal
domain. AVEN also participates in the DNA damage response, where ATM phosphorylates it at
Ser135/Ser138 to promote G2/M checkpoint arrest. AVEN is overexpressed in hematologic
malignancies and contributes to chemotherapy resistance.
existing_annotations:
- term:
id: GO:0010972
label: negative regulation of G2/M transition of mitotic cell cycle
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
AVEN participates in the DNA damage response and promotes G2/M checkpoint arrest. ATM
phosphorylates AVEN at Ser135 and Ser138 upon DNA damage, and these phosphorylation
sites are required for AVEN-driven checkpoint function. This IBA annotation is
phylogenetically inferred and is consistent with experimental evidence showing AVEN's
role in DNA damage checkpoint signaling.
action: KEEP_AS_NON_CORE
reason: >-
While AVEN does contribute to G2/M checkpoint arrest via ATM-dependent phosphorylation,
this represents a secondary/modulatory function rather than AVEN's core anti-apoptotic
role. The primary function of AVEN is inhibition of apoptosome assembly and BCL-xL
stabilization. The checkpoint function is mechanistically distinct and should be
retained as a non-core annotation.
supported_by:
- reference_id: file:human/AVEN/AVEN-deep-research-falcon.md
supporting_text: "ATM phosphorylates Aven at Ser135 and Ser138, and these sites are required for Aven-driven checkpoint function"
- term:
id: GO:0006915
label: apoptotic process
evidence_type: IEA
original_reference_id: GO_REF:0000043
review:
summary: >-
This IEA annotation is based on the UniProt keyword 'Apoptosis'. AVEN is indeed involved
in apoptosis, but as a negative regulator. The term 'apoptotic process' is too general
and does not capture AVEN's specific anti-apoptotic function. AVEN inhibits the intrinsic
apoptosis pathway by binding Apaf-1 and preventing apoptosome assembly, and by stabilizing
BCL-xL.
action: MODIFY
reason: >-
The annotation is not wrong (AVEN is involved in the apoptotic process), but it lacks
specificity. AVEN specifically negatively regulates apoptosis through direct inhibition
of apoptosome assembly and BCL-xL stabilization. A more informative annotation would be
'negative regulation of apoptotic process' (GO:0043066), which is already annotated
with IDA evidence.
proposed_replacement_terms:
- id: GO:0043066
label: negative regulation of apoptotic process
supported_by:
- reference_id: PMID:10949025
supporting_text: "Aven interferes with the ability of Apaf-1 to self-associate, suggesting that Aven impairs Apaf-1-mediated activation of caspases. Consistent with this idea, Aven inhibited the proteolytic activation of caspases in a cell-free extract and suppressed apoptosis induced by Apaf-1 plus caspase-9."
- term:
id: GO:0012505
label: endomembrane system
evidence_type: IEA
original_reference_id: GO_REF:0000044
review:
summary: >-
This IEA annotation is based on UniProt subcellular location mapping. UniProt states AVEN
is "Associated with intracellular membranes" and is a peripheral membrane protein of the
endomembrane system. The original Chau et al. 2000 paper showed AVEN localizes to light
membrane/vesicular fractions with diffuse nuclear and reticular cytoplasmic staining.
Later work showed AVEN co-localizes with cathepsin D in vesicular compartments.
action: ACCEPT
reason: >-
The annotation is consistent with experimental evidence showing AVEN association with
intracellular membranes and vesicular compartments. This localization is functionally
relevant as cathepsin D processing of AVEN in vesicular compartments releases its
anti-apoptotic potential.
supported_by:
- reference_id: PMID:10949025
supporting_text: "Aven, a novel inhibitor of caspase activation, binds Bcl-xL and Apaf-1"
- reference_id: file:human/AVEN/AVEN-deep-research-falcon.md
supporting_text: "Aven localizes mainly to light membrane/vesicular fractions, with diffuse nuclear and reticular cytoplasmic staining; it can co-localize with cathepsin D (CathD) in vesicular compartments"
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:10949025
review:
summary: >-
This annotation reflects AVEN's binding to APAF1 (O14727) and BCL2L1/BCL-xL (Q07817).
While the interactions are well-documented (AVEN was discovered through yeast two-hybrid
screen for BCL-xL interactors), the term 'protein binding' is uninformative. More specific
molecular function terms should be used.
action: REMOVE
reason: >-
The term 'protein binding' (GO:0005515) is too generic to be informative. AVEN has
specific, characterized binding partners (Apaf-1 and BCL-xL) with defined functional
consequences. The binding to Apaf-1 inhibits apoptosome assembly, while BCL-xL binding
stabilizes and potentiates this anti-apoptotic protein. More specific terms like
'BH domain binding' (GO:0051400) for BCL-xL interaction would be more appropriate,
though the core function is better captured by process annotations.
supported_by:
- reference_id: PMID:10949025
supporting_text: "Aven is broadly expressed and is conserved in other mammalian species. Only those mutants of Bcl-x(L)that retain their antiapoptotic activity are capable of binding Aven."
- term:
id: GO:0005829
label: cytosol
evidence_type: TAS
original_reference_id: Reactome:R-HSA-6805507
review:
summary: >-
This TAS annotation from Reactome reflects AVEN localization in the cytosol where it
can interact with Apaf-1 to inhibit apoptosome assembly. Apoptosome formation occurs
in the cytosol following cytochrome c release from mitochondria, so cytosolic
localization of AVEN is required for its anti-apoptotic function.
action: ACCEPT
reason: >-
Cytosolic localization is consistent with AVEN's function as an inhibitor of
apoptosome assembly. The Reactome pathway 'APAF1 binds AVEN' documents this
interaction in the cytosol. AVEN also associates with membrane fractions, but
cytosolic AVEN is the pool that interacts with Apaf-1 to prevent caspase activation.
supported_by:
- reference_id: Reactome:R-HSA-6805507
supporting_text: "The binding of AVEN to apoptotic protease activating factor 1 (APAF1) is thought to interfere with the ability of APAF1 to self-associate during apoptosome assembly"
- term:
id: GO:0016020
label: membrane
evidence_type: IDA
original_reference_id: PMID:10949025
review:
summary: >-
This IDA annotation indicates AVEN associates with membranes. The original Chau et al.
paper showed AVEN localizes to light membrane fractions by subcellular fractionation.
UniProt describes AVEN as a peripheral membrane protein of the endomembrane system.
action: ACCEPT
reason: >-
The membrane localization is experimentally validated and functionally relevant.
AVEN co-localizes with cathepsin D in vesicular/membrane compartments where
proteolytic processing removes the N-terminal inhibitory domain to unleash AVEN's
full anti-apoptotic activity. Both cytosolic and membrane-associated pools of AVEN
are physiologically relevant.
supported_by:
- reference_id: PMID:10949025
supporting_text: "Aven, a novel inhibitor of caspase activation, binds Bcl-xL and Apaf-1"
- reference_id: file:human/AVEN/AVEN-deep-research-falcon.md
supporting_text: "Biochemical fractionation and microscopy place Aven in light membrane/vesicular pools and nucleus/cytoplasm"
- term:
id: GO:0043066
label: negative regulation of apoptotic process
evidence_type: IDA
original_reference_id: PMID:10949025
review:
summary: >-
This is the core functional annotation for AVEN. AVEN negatively regulates apoptosis
through two mechanisms: (1) binding Apaf-1 and interfering with its self-association,
thereby blocking apoptosome assembly and caspase-9 activation; (2) binding and
stabilizing BCL-xL to potentiate its anti-apoptotic function. Chau et al. demonstrated
that AVEN inhibited caspase proteolytic activation in cell-free extracts and suppressed
apoptosis induced by Apaf-1 plus caspase-9. AVEN also protected against death in a
mouse Sindbis virus infection model.
action: ACCEPT
reason: >-
This annotation accurately captures AVEN's core function as an anti-apoptotic regulator.
The IDA evidence from the original discovery paper is strong, demonstrating both
biochemical inhibition of caspase activation and cellular protection from apoptosis.
This is a legitimate, evolved anti-apoptotic function, not a downstream metabolic effect.
supported_by:
- reference_id: PMID:10949025
supporting_text: "Aven interferes with the ability of Apaf-1 to self-associate, suggesting that Aven impairs Apaf-1-mediated activation of caspases. Consistent with this idea, Aven inhibited the proteolytic activation of caspases in a cell-free extract and suppressed apoptosis induced by Apaf-1 plus caspase-9."
- term:
id: GO:1905101
label: negative regulation of apoptosome assembly
evidence_type: IDA
original_reference_id: PMID:10949025
review:
summary: >-
AVEN directly inhibits apoptosome assembly by binding Apaf-1 and preventing its
self-association. This is the specific mechanistic step at which AVEN acts to
inhibit apoptosis.
action: NEW
reason: >-
This term (GO:1905101) more precisely describes AVEN's mechanism of action than
the broader 'negative regulation of apoptotic process'. AVEN binds Apaf-1 and
interferes with its oligomerization, which is required for apoptosome formation.
This is the proximal step that AVEN inhibits to block caspase activation.
supported_by:
- reference_id: PMID:10949025
supporting_text: "Aven interferes with the ability of Apaf-1 to self-associate, suggesting that Aven impairs Apaf-1-mediated activation of caspases."
- reference_id: Reactome:R-HSA-6805507
supporting_text: "The binding of AVEN to apoptotic protease activating factor 1 (APAF1) is thought to interfere with the ability of APAF1 to self-associate during apoptosome assembly"
- term:
id: GO:0051400
label: BH domain binding
evidence_type: IDA
original_reference_id: PMID:10949025
review:
summary: >-
AVEN binds BCL-xL (BCL2L1), an anti-apoptotic BCL-2 family member. AVEN was originally
identified by yeast two-hybrid screen for BCL-xL interactors. Computational analysis
has identified a predicted BH3-like motif in AVEN (aa 141-153) that may mediate
this interaction. Only BCL-xL mutants that retain anti-apoptotic activity can bind AVEN.
action: NEW
reason: >-
This molecular function annotation would capture AVEN's specific interaction with
BCL-xL through the BH domain binding interface. This is more informative than
generic 'protein binding' and reflects the BH3-like motif in AVEN that mediates
the interaction.
supported_by:
- reference_id: PMID:10949025
supporting_text: "Only those mutants of Bcl-x(L)that retain their antiapoptotic activity are capable of binding Aven."
- reference_id: file:human/AVEN/AVEN-deep-research-falcon.md
supporting_text: "Computational/biophysical analyses identified a BH3-like segment in Aven (aa 141-153) predicted to bind BCL-xL with appreciable affinity"
references:
- 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:0000044
title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
vocabulary mapping, accompanied by conservative changes to GO terms applied by
UniProt
findings: []
- id: PMID:10949025
title: Aven, a novel inhibitor of caspase activation, binds Bcl-xL and Apaf-1.
findings:
- statement: AVEN was identified by yeast two-hybrid screen for BCL-xL interactors
- statement: AVEN binds both BCL-xL and Apaf-1
- statement: AVEN interferes with Apaf-1 self-association
- statement: AVEN inhibits caspase proteolytic activation in cell-free extracts
- statement: AVEN suppresses apoptosis induced by Apaf-1 plus caspase-9
- statement: AVEN is broadly expressed and conserved in mammals
- statement: AVEN localizes to light membrane/vesicular fractions
- id: Reactome:R-HSA-6805507
title: APAF1 binds AVEN
findings:
- statement: AVEN binding to APAF1 interferes with APAF1 self-association during apoptosome assembly
- statement: Anti-apoptotic function of AVEN may require proteolytic removal of inhibitory N-terminus
- id: file:human/AVEN/AVEN-deep-research-falcon.md
title: Deep research synthesis for AVEN
findings:
- statement: AVEN binds and stabilizes BCL-xL, potentiating its anti-apoptotic function
- statement: Cathepsin D cleaves AVEN N-terminus at aa 144/145 and 196/197 to unleash anti-apoptotic activity
- statement: AVEN contains a predicted BH3-like motif (aa 141-153) for BCL-xL interaction
- statement: ATM phosphorylates AVEN at Ser135/Ser138 for G2/M checkpoint function
- statement: AVEN is overexpressed in acute leukemias with adverse outcomes
core_functions:
- molecular_function:
id: GO:0051400
label: BH domain binding
description: >-
AVEN binds BCL-xL through a predicted BH3-like motif (aa 141-153), stabilizing BCL-xL
and potentiating its anti-apoptotic function. Only BCL-xL mutants retaining
anti-apoptotic activity can bind AVEN.
directly_involved_in:
- id: GO:0043066
label: negative regulation of apoptotic process
- id: GO:1905101
label: negative regulation of apoptosome assembly
locations:
- id: GO:0005829
label: cytosol
- id: GO:0016020
label: membrane