{"gene":"PARVB","run_date":"2026-06-10T05:19:53","timeline":{"discoveries":[{"year":2003,"finding":"PARVB (beta-parvin) physically interacts with ARHGEF6 (alphaPIX), as demonstrated by yeast two-hybrid screening, co-immunoprecipitation, and GST pull-down assays. Both the N-terminal calponin homology (CH) domain and C-terminal coiled-coil domain of ARHGEF6 are required for the interaction. PARVB and ARHGEF6 co-localize at lamellipodia and ruffles in cells spreading on fibronectin, placing PARVB upstream of Rac1/Cdc42 activation in integrin-mediated signaling.","method":"Yeast two-hybrid, co-immunoprecipitation, GST pull-down, immunofluorescence co-localization, domain-deletion mutagenesis","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding confirmed by three orthogonal methods (Y2H, Co-IP, GST pull-down) plus mutagenesis mapping of required domains and co-localization","pmids":["12499396"],"is_preprint":false},{"year":2024,"finding":"PARVB associates with TAK1 (transforming growth factor-β-activated kinase 1) and prevents its ubiquitination by blocking the E3 ligase ITCH from binding TAK1. Conditional knockout of PARVB in proximal tubular epithelial cells promotes cisplatin-induced TAK1 degradation, inhibits TAK1 downstream signaling, and alleviates tubular cell death and inflammation. Restoration of PARVB or TAK1 in PARVB-deficient cells rescues cisplatin-induced injury, placing PARVB as a regulator of TAK1 protein stability via an ITCH-dependent ubiquitination pathway.","method":"Conditional knockout (Cre-LoxP), co-immunoprecipitation (PARVB-TAK1 and ITCH-TAK1 interaction), ubiquitination assay, rescue experiments with PARVB/TAK1 re-expression, in vivo mouse model","journal":"Cellular and molecular life sciences : CMLS","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean conditional KO with defined cellular phenotype, Co-IP of PARVB-TAK1-ITCH interactions, rescue experiments, and in vivo validation in single rigorous study","pmids":["39235496"],"is_preprint":false},{"year":2024,"finding":"PARVB knockdown in tongue squamous cell carcinoma cells causes decreases in cell migration and wound healing, establishing PARVB as a functionally required driver of cell motility.","method":"siRNA knockdown, cell migration assay, wound healing assay","journal":"British journal of cancer","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — loss-of-function with defined cellular phenotype (migration/wound healing), single lab, two related but not fully orthogonal methods","pmids":["25422907"],"is_preprint":false},{"year":2024,"finding":"In Fascin2 (Fscn2) knockout cochlear cells, PARVB is upregulated and this upregulation is associated with decreased ILK, p-ILK, p-AKT, and Bcl-2 levels and increased cleaved-Caspase9. Knockdown of PARVB in HEI-OC1 cells promotes cell proliferation, migration, and rescues ILK-AKT pathway activity. FSCN2 negatively regulates PARVB expression by inhibiting PPAR-γ nuclear translocation, placing PARVB downstream of FSCN2/PPAR-γ and upstream of the ILK-AKT survival pathway.","method":"Fscn2 knockout mouse model, microarray, siRNA knockdown, PARVB/Fscn2 overexpression, Western blot (ILK, p-ILK, p-AKT, Bcl-2, Caspase9), PPAR-γ inhibitor (GW9662), cell proliferation and migration assays","journal":"Cell death discovery","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO plus pharmacological inhibition plus rescue experiments, single lab, multiple molecular readouts but no direct biochemical reconstitution of PARVB-ILK interaction","pmids":["38374196"],"is_preprint":false},{"year":2024,"finding":"HIF-1α/2α transcription factors elevate PARVB expression under hypoxic conditions by binding to a hypoxia-responsive element in the PARVB promoter. Silencing PARVB reduces melanoma cell proliferation, migration, and invasion in vitro and decelerates tumor growth in vivo.","method":"HIF-1α/2α knockdown, PARVB promoter hypoxia-responsive element analysis, in vitro proliferation/migration/invasion assays, in vivo xenograft","journal":"Translational oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — defined transcriptional regulatory mechanism (HIF binding to promoter) plus loss-of-function with cellular and in vivo phenotype, single lab","pmids":["38301409"],"is_preprint":false},{"year":2021,"finding":"PARVB promotes glioblastoma cell proliferation, migration, and invasion partially through activation of the JAK2/STAT3 pathway and induction of epithelial-mesenchymal transition (EMT), as demonstrated by in vitro functional assays.","method":"In vitro knockdown/overexpression, cell proliferation, migration and invasion assays, JAK2/STAT3 pathway analysis","journal":"Frontiers in oncology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — in vitro functional assays with partial pathway analysis, single lab, no direct biochemical or structural validation of PARVB-JAK2/STAT3 interaction","pmids":["34568031"],"is_preprint":false},{"year":2025,"finding":"PARVB is upregulated in PALB2-mutated breast epithelial cells and knockdown of PARVB reduces cell migration and morphological abnormalities of PALB2-mutated spheroids. Furthermore, macropinocytosis is enhanced in PALB2-mutated cells in a PARVB-dependent manner.","method":"siRNA knockdown, cell migration assay, 3D spheroid morphology, macropinocytosis assay (dextran uptake)","journal":"Biochemical and biophysical research communications","confidence":"Low","confidence_rationale":"Tier 3 / Weak — loss-of-function with cellular phenotype, single lab, no direct mechanistic pathway placement for PARVB action downstream of PALB2","pmids":["40730089"],"is_preprint":false},{"year":2025,"finding":"PARVB activates the SMAD signaling axis leading to upregulation of TNFSF13, which promotes M2 macrophage polarization; this PARVB-SMAD3-TNFSF13 axis enhances immunosuppressive interactions and drives tumor proliferation, as supported by functional assays and multiplex immunohistochemistry in cervical cancer.","method":"Transcriptomic/single-cell RNA-seq analysis, functional assays, multiplex immunohistochemistry","journal":"Laboratory investigation; a journal of technical methods and pathology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — pathway inference primarily from transcriptomic data and IHC with limited direct biochemical validation of PARVB-SMAD3 interaction, single lab","pmids":["40744226"],"is_preprint":false}],"current_model":"PARVB (beta-parvin) is a focal adhesion actin-binding protein that acts as a scaffold linking integrin signaling to Rho GTPase activation: it directly binds ARHGEF6 (alphaPIX) via its CH and coiled-coil domains to couple integrin engagement to Rac1/Cdc42 activation at lamellipodia, regulates cell survival by stabilizing TAK1 protein through prevention of ITCH-mediated ubiquitination, and negatively modulates the ILK-AKT survival pathway; its expression is transcriptionally induced under hypoxia via HIF-1α/2α binding to its promoter, and its overexpression promotes cell migration, invasion, and EMT in multiple cancer contexts."},"narrative":{"mechanistic_narrative":"PARVB (beta-parvin) is a focal adhesion adaptor that couples integrin engagement to Rho-family GTPase signaling and cell motility [PMID:12499396]. It physically interacts with the guanine nucleotide exchange factor ARHGEF6 (alphaPIX) through both the CH and coiled-coil domains of ARHGEF6, and the two proteins co-localize at lamellipodia and ruffles in cells spreading on fibronectin, placing PARVB upstream of Rac1/Cdc42 activation [PMID:12499396]. PARVB also operates as a regulator of cell survival: it associates with the kinase TAK1 and protects it from degradation by blocking the E3 ligase ITCH from binding and ubiquitinating TAK1, so that loss of PARVB promotes TAK1 degradation and sensitizes proximal tubular epithelial cells to cisplatin-induced death and inflammation [PMID:39235496]. In a separate survival axis, PARVB acts downstream of FSCN2/PPAR-γ and negatively modulates the ILK–AKT pathway, with PARVB knockdown restoring ILK-AKT activity and promoting proliferation and migration [PMID:38374196]. PARVB expression is transcriptionally induced under hypoxia through HIF-1α/2α binding to a hypoxia-responsive element in its promoter, and its function as a driver of cell migration, invasion, and proliferation has been demonstrated across melanoma and tongue squamous cell carcinoma models [PMID:25422907, PMID:38301409].","teleology":[{"year":2003,"claim":"Established the first direct molecular partner of PARVB, linking it physically to the integrin-to-GTPase signaling machinery rather than treating it as a generic adhesion protein.","evidence":"Yeast two-hybrid, reciprocal Co-IP, GST pull-down, domain-deletion mapping, and immunofluorescence co-localization on fibronectin","pmids":["12499396"],"confidence":"High","gaps":["Whether PARVB directly modulates ARHGEF6 GEF activity toward Rac1/Cdc42 was not measured","No structural detail of the PARVB-ARHGEF6 interface"]},{"year":2024,"claim":"Defined a survival role for PARVB by showing it stabilizes TAK1 protein through competitive blockade of ITCH-mediated ubiquitination, explaining how PARVB loss sensitizes cells to injury.","evidence":"Conditional Cre-LoxP knockout in proximal tubular epithelium, Co-IP of PARVB-TAK1 and ITCH-TAK1, ubiquitination assay, and PARVB/TAK1 rescue plus in vivo cisplatin model","pmids":["39235496"],"confidence":"High","gaps":["Whether PARVB occludes the ITCH binding site directly or allosterically is unresolved","Generalizability beyond renal tubular cells untested"]},{"year":2024,"claim":"Positioned PARVB within the FSCN2/PPAR-γ axis as a negative modulator of the ILK-AKT survival pathway in cochlear cells.","evidence":"Fscn2 knockout mouse, microarray, siRNA knockdown, overexpression rescue, PPAR-γ inhibition, and Western blot of ILK/p-AKT/Bcl-2/Caspase9","pmids":["38374196"],"confidence":"Medium","gaps":["No direct biochemical reconstitution of a PARVB-ILK interaction","Mechanism by which PARVB suppresses ILK activity unclear"]},{"year":2024,"claim":"Identified hypoxia as an upstream transcriptional driver of PARVB and tied its expression to tumor cell motility and growth.","evidence":"HIF-1α/2α knockdown, promoter hypoxia-responsive element analysis, in vitro proliferation/migration/invasion assays, and melanoma xenograft","pmids":["38301409"],"confidence":"Medium","gaps":["Direct HIF binding to the PARVB promoter element not shown by ChIP","Downstream effectors of PARVB in melanoma not defined"]},{"year":2024,"claim":"Confirmed PARVB as a functionally required driver of cell motility in a second cancer context.","evidence":"siRNA knockdown with migration and wound-healing assays in tongue squamous cell carcinoma cells","pmids":["25422907"],"confidence":"Medium","gaps":["No molecular pathway linking PARVB to migration in this model","Single lab, related rather than orthogonal assays"]},{"year":2025,"claim":"Extended PARVB's pro-tumor role to additional contexts and candidate effector pathways (JAK2/STAT3 and EMT, PALB2-dependent macropinocytosis, and a SMAD3-TNFSF13 immunosuppressive axis).","evidence":"In vitro knockdown/overexpression, 3D spheroid and macropinocytosis assays, transcriptomic/scRNA-seq and multiplex IHC across glioblastoma, PALB2-mutated breast, and cervical cancer","pmids":["34568031","40730089","40744226"],"confidence":"Low","gaps":["No direct biochemical validation of PARVB-JAK2/STAT3 or PARVB-SMAD3 interactions","Mechanism placing PARVB downstream of PALB2 unresolved","Pathway links inferred largely from transcriptomic/IHC correlation"]},{"year":null,"claim":"How PARVB integrates its distinct roles—ARHGEF6/GTPase scaffolding, TAK1 stabilization, and ILK-AKT modulation—into a unified mechanism, and which domains govern each, remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of PARVB defining domain-specific partner binding","Whether the survival and migration functions are mechanistically coupled is unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[1,3]}],"complexes":[],"partners":["ARHGEF6","TAK1","ITCH"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9HBI1","full_name":"Beta-parvin","aliases":["Affixin"],"length_aa":364,"mass_kda":41.7,"function":"Adapter protein that plays a role in integrin signaling via ILK and in activation of the GTPases CDC42 and RAC1 by guanine exchange factors, such as ARHGEF6. Is involved in the reorganization of the actin cytoskeleton and formation of lamellipodia. Plays a role in cell adhesion, cell spreading, establishment or maintenance of cell polarity, and cell migration","subcellular_location":"Cell junction, focal adhesion; Cell membrane; Cytoplasm, cytoskeleton; Cell projection, lamellipodium; Cytoplasm, myofibril, sarcomere; Cytoplasm, myofibril, sarcomere, Z line","url":"https://www.uniprot.org/uniprotkb/Q9HBI1/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PARVB","classification":"Not Classified","n_dependent_lines":4,"n_total_lines":1208,"dependency_fraction":0.0033112582781456954},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"ILK","stoichiometry":10.0},{"gene":"HMGN2","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/PARVB","total_profiled":1310},"omim":[{"mim_id":"619100","title":"COILED-COIL DOMAIN-CONTAINING PROTEIN 25; CCDC25","url":"https://www.omim.org/entry/619100"},{"mim_id":"608682","title":"ADRENOMEDULLIN 2; ADM2","url":"https://www.omim.org/entry/608682"},{"mim_id":"608122","title":"PARVIN, GAMMA; PARVG","url":"https://www.omim.org/entry/608122"},{"mim_id":"608121","title":"PARVIN, BETA; PARVB","url":"https://www.omim.org/entry/608121"},{"mim_id":"606232","title":"PHELAN-MCDERMID SYNDROME; PHMDS","url":"https://www.omim.org/entry/606232"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Plasma membrane","reliability":"Supported"},{"location":"Actin filaments","reliability":"Supported"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"skeletal muscle","ntpm":183.6},{"tissue":"tongue","ntpm":159.4}],"url":"https://www.proteinatlas.org/search/PARVB"},"hgnc":{"alias_symbol":["CGI-56"],"prev_symbol":[]},"alphafold":{"accession":"Q9HBI1","domains":[{"cath_id":"1.10.418.10","chopping":"78-204_227-234","consensus_level":"high","plddt":90.4636,"start":78,"end":234},{"cath_id":"1.10.418.10","chopping":"238-362","consensus_level":"high","plddt":93.1763,"start":238,"end":362}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9HBI1","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9HBI1-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9HBI1-F1-predicted_aligned_error_v6.png","plddt_mean":81.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PARVB","jax_strain_url":"https://www.jax.org/strain/search?query=PARVB"},"sequence":{"accession":"Q9HBI1","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9HBI1.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9HBI1/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9HBI1"}},"corpus_meta":[{"pmid":"23535911","id":"PMC_23535911","title":"Genome-wide scan revealed that polymorphisms in the PNPLA3, SAMM50, and PARVB genes are associated with development and progression of nonalcoholic fatty liver disease in Japan.","date":"2013","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23535911","citation_count":165,"is_preprint":false},{"pmid":"12499396","id":"PMC_12499396","title":"Interaction of alphaPIX (ARHGEF6) with beta-parvin (PARVB) suggests an involvement of alphaPIX in integrin-mediated signaling.","date":"2003","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/12499396","citation_count":104,"is_preprint":false},{"pmid":"25776890","id":"PMC_25776890","title":"Targeted-bisulfite sequence analysis of the methylation of CpG islands in genes encoding PNPLA3, SAMM50, and PARVB of patients with non-alcoholic fatty liver disease.","date":"2015","source":"Journal of hepatology","url":"https://pubmed.ncbi.nlm.nih.gov/25776890","citation_count":70,"is_preprint":false},{"pmid":"25422907","id":"PMC_25422907","title":"PARVB overexpression increases cell migration capability and defines high risk for endophytic growth and metastasis in tongue squamous cell carcinoma.","date":"2014","source":"British journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/25422907","citation_count":30,"is_preprint":false},{"pmid":"24621583","id":"PMC_24621583","title":"Targeted next-generation sequencing and fine linkage disequilibrium mapping reveals association of PNPLA3 and PARVB with the severity of nonalcoholic fatty liver disease.","date":"2014","source":"Journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/24621583","citation_count":18,"is_preprint":false},{"pmid":"34568031","id":"PMC_34568031","title":"Construction of Novel Methylation-Driven Gene Model and Investigation of PARVB Function in Glioblastoma.","date":"2021","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/34568031","citation_count":12,"is_preprint":false},{"pmid":"26343796","id":"PMC_26343796","title":"Association of rs5764455 and rs6006473 polymorphisms in PARVB with liver damage of nonalcoholic fatty liver disease in Han Chinese population.","date":"2015","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/26343796","citation_count":11,"is_preprint":false},{"pmid":"35528982","id":"PMC_35528982","title":"Interaction of SAMM50-rs738491, PARVB-rs5764455 and PNPLA3-rs738409 Increases Susceptibility to Nonalcoholic Steatohepatitis.","date":"2021","source":"Journal of clinical and translational hepatology","url":"https://pubmed.ncbi.nlm.nih.gov/35528982","citation_count":10,"is_preprint":false},{"pmid":"23950981","id":"PMC_23950981","title":"Pathway analysis using genome-wide association study data for coronary restenosis--a potential role for the PARVB gene.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23950981","citation_count":9,"is_preprint":false},{"pmid":"38301409","id":"PMC_38301409","title":"PARVB promotes malignant melanoma progression and is enhanced by hypoxic conditions.","date":"2024","source":"Translational oncology","url":"https://pubmed.ncbi.nlm.nih.gov/38301409","citation_count":3,"is_preprint":false},{"pmid":"39235496","id":"PMC_39235496","title":"PARVB deficiency alleviates cisplatin-induced tubular injury by inhibiting TAK1 signaling.","date":"2024","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/39235496","citation_count":3,"is_preprint":false},{"pmid":"38374196","id":"PMC_38374196","title":"Inhibition of the ILK-AKT pathway by upregulation of PARVB contributes to the cochlear cell death in Fascin2 gene knockout mice.","date":"2024","source":"Cell death discovery","url":"https://pubmed.ncbi.nlm.nih.gov/38374196","citation_count":3,"is_preprint":false},{"pmid":"40744226","id":"PMC_40744226","title":"Potential Role of PARVB in Macrophage-Mediated Immunosuppression and Cervical Cancer Progression.","date":"2025","source":"Laboratory investigation; a journal of technical methods and pathology","url":"https://pubmed.ncbi.nlm.nih.gov/40744226","citation_count":0,"is_preprint":false},{"pmid":"40730089","id":"PMC_40730089","title":"PALB2 mutations increase oncogenic properties of breast epithelial cells by enhancing JAM3 and PARVB expression.","date":"2025","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/40730089","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10445,"output_tokens":2340,"usd":0.033217,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9436,"output_tokens":2528,"usd":0.05519,"stage2_stop_reason":"end_turn"},"total_usd":0.088407,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"PARVB (beta-parvin) physically interacts with ARHGEF6 (alphaPIX), as demonstrated by yeast two-hybrid screening, co-immunoprecipitation, and GST pull-down assays. Both the N-terminal calponin homology (CH) domain and C-terminal coiled-coil domain of ARHGEF6 are required for the interaction. PARVB and ARHGEF6 co-localize at lamellipodia and ruffles in cells spreading on fibronectin, placing PARVB upstream of Rac1/Cdc42 activation in integrin-mediated signaling.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, GST pull-down, immunofluorescence co-localization, domain-deletion mutagenesis\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding confirmed by three orthogonal methods (Y2H, Co-IP, GST pull-down) plus mutagenesis mapping of required domains and co-localization\",\n      \"pmids\": [\"12499396\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"PARVB associates with TAK1 (transforming growth factor-β-activated kinase 1) and prevents its ubiquitination by blocking the E3 ligase ITCH from binding TAK1. Conditional knockout of PARVB in proximal tubular epithelial cells promotes cisplatin-induced TAK1 degradation, inhibits TAK1 downstream signaling, and alleviates tubular cell death and inflammation. Restoration of PARVB or TAK1 in PARVB-deficient cells rescues cisplatin-induced injury, placing PARVB as a regulator of TAK1 protein stability via an ITCH-dependent ubiquitination pathway.\",\n      \"method\": \"Conditional knockout (Cre-LoxP), co-immunoprecipitation (PARVB-TAK1 and ITCH-TAK1 interaction), ubiquitination assay, rescue experiments with PARVB/TAK1 re-expression, in vivo mouse model\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean conditional KO with defined cellular phenotype, Co-IP of PARVB-TAK1-ITCH interactions, rescue experiments, and in vivo validation in single rigorous study\",\n      \"pmids\": [\"39235496\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"PARVB knockdown in tongue squamous cell carcinoma cells causes decreases in cell migration and wound healing, establishing PARVB as a functionally required driver of cell motility.\",\n      \"method\": \"siRNA knockdown, cell migration assay, wound healing assay\",\n      \"journal\": \"British journal of cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — loss-of-function with defined cellular phenotype (migration/wound healing), single lab, two related but not fully orthogonal methods\",\n      \"pmids\": [\"25422907\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In Fascin2 (Fscn2) knockout cochlear cells, PARVB is upregulated and this upregulation is associated with decreased ILK, p-ILK, p-AKT, and Bcl-2 levels and increased cleaved-Caspase9. Knockdown of PARVB in HEI-OC1 cells promotes cell proliferation, migration, and rescues ILK-AKT pathway activity. FSCN2 negatively regulates PARVB expression by inhibiting PPAR-γ nuclear translocation, placing PARVB downstream of FSCN2/PPAR-γ and upstream of the ILK-AKT survival pathway.\",\n      \"method\": \"Fscn2 knockout mouse model, microarray, siRNA knockdown, PARVB/Fscn2 overexpression, Western blot (ILK, p-ILK, p-AKT, Bcl-2, Caspase9), PPAR-γ inhibitor (GW9662), cell proliferation and migration assays\",\n      \"journal\": \"Cell death discovery\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO plus pharmacological inhibition plus rescue experiments, single lab, multiple molecular readouts but no direct biochemical reconstitution of PARVB-ILK interaction\",\n      \"pmids\": [\"38374196\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"HIF-1α/2α transcription factors elevate PARVB expression under hypoxic conditions by binding to a hypoxia-responsive element in the PARVB promoter. Silencing PARVB reduces melanoma cell proliferation, migration, and invasion in vitro and decelerates tumor growth in vivo.\",\n      \"method\": \"HIF-1α/2α knockdown, PARVB promoter hypoxia-responsive element analysis, in vitro proliferation/migration/invasion assays, in vivo xenograft\",\n      \"journal\": \"Translational oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — defined transcriptional regulatory mechanism (HIF binding to promoter) plus loss-of-function with cellular and in vivo phenotype, single lab\",\n      \"pmids\": [\"38301409\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PARVB promotes glioblastoma cell proliferation, migration, and invasion partially through activation of the JAK2/STAT3 pathway and induction of epithelial-mesenchymal transition (EMT), as demonstrated by in vitro functional assays.\",\n      \"method\": \"In vitro knockdown/overexpression, cell proliferation, migration and invasion assays, JAK2/STAT3 pathway analysis\",\n      \"journal\": \"Frontiers in oncology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — in vitro functional assays with partial pathway analysis, single lab, no direct biochemical or structural validation of PARVB-JAK2/STAT3 interaction\",\n      \"pmids\": [\"34568031\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PARVB is upregulated in PALB2-mutated breast epithelial cells and knockdown of PARVB reduces cell migration and morphological abnormalities of PALB2-mutated spheroids. Furthermore, macropinocytosis is enhanced in PALB2-mutated cells in a PARVB-dependent manner.\",\n      \"method\": \"siRNA knockdown, cell migration assay, 3D spheroid morphology, macropinocytosis assay (dextran uptake)\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — loss-of-function with cellular phenotype, single lab, no direct mechanistic pathway placement for PARVB action downstream of PALB2\",\n      \"pmids\": [\"40730089\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PARVB activates the SMAD signaling axis leading to upregulation of TNFSF13, which promotes M2 macrophage polarization; this PARVB-SMAD3-TNFSF13 axis enhances immunosuppressive interactions and drives tumor proliferation, as supported by functional assays and multiplex immunohistochemistry in cervical cancer.\",\n      \"method\": \"Transcriptomic/single-cell RNA-seq analysis, functional assays, multiplex immunohistochemistry\",\n      \"journal\": \"Laboratory investigation; a journal of technical methods and pathology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — pathway inference primarily from transcriptomic data and IHC with limited direct biochemical validation of PARVB-SMAD3 interaction, single lab\",\n      \"pmids\": [\"40744226\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PARVB (beta-parvin) is a focal adhesion actin-binding protein that acts as a scaffold linking integrin signaling to Rho GTPase activation: it directly binds ARHGEF6 (alphaPIX) via its CH and coiled-coil domains to couple integrin engagement to Rac1/Cdc42 activation at lamellipodia, regulates cell survival by stabilizing TAK1 protein through prevention of ITCH-mediated ubiquitination, and negatively modulates the ILK-AKT survival pathway; its expression is transcriptionally induced under hypoxia via HIF-1α/2α binding to its promoter, and its overexpression promotes cell migration, invasion, and EMT in multiple cancer contexts.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PARVB (beta-parvin) is a focal adhesion adaptor that couples integrin engagement to Rho-family GTPase signaling and cell motility [#0]. It physically interacts with the guanine nucleotide exchange factor ARHGEF6 (alphaPIX) through both the CH and coiled-coil domains of ARHGEF6, and the two proteins co-localize at lamellipodia and ruffles in cells spreading on fibronectin, placing PARVB upstream of Rac1/Cdc42 activation [#0]. PARVB also operates as a regulator of cell survival: it associates with the kinase TAK1 and protects it from degradation by blocking the E3 ligase ITCH from binding and ubiquitinating TAK1, so that loss of PARVB promotes TAK1 degradation and sensitizes proximal tubular epithelial cells to cisplatin-induced death and inflammation [#1]. In a separate survival axis, PARVB acts downstream of FSCN2/PPAR-\\u03b3 and negatively modulates the ILK\\u2013AKT pathway, with PARVB knockdown restoring ILK-AKT activity and promoting proliferation and migration [#3]. PARVB expression is transcriptionally induced under hypoxia through HIF-1\\u03b1/2\\u03b1 binding to a hypoxia-responsive element in its promoter, and its function as a driver of cell migration, invasion, and proliferation has been demonstrated across melanoma and tongue squamous cell carcinoma models [#2, #4].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Established the first direct molecular partner of PARVB, linking it physically to the integrin-to-GTPase signaling machinery rather than treating it as a generic adhesion protein.\",\n      \"evidence\": \"Yeast two-hybrid, reciprocal Co-IP, GST pull-down, domain-deletion mapping, and immunofluorescence co-localization on fibronectin\",\n      \"pmids\": [\"12499396\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PARVB directly modulates ARHGEF6 GEF activity toward Rac1/Cdc42 was not measured\", \"No structural detail of the PARVB-ARHGEF6 interface\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined a survival role for PARVB by showing it stabilizes TAK1 protein through competitive blockade of ITCH-mediated ubiquitination, explaining how PARVB loss sensitizes cells to injury.\",\n      \"evidence\": \"Conditional Cre-LoxP knockout in proximal tubular epithelium, Co-IP of PARVB-TAK1 and ITCH-TAK1, ubiquitination assay, and PARVB/TAK1 rescue plus in vivo cisplatin model\",\n      \"pmids\": [\"39235496\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PARVB occludes the ITCH binding site directly or allosterically is unresolved\", \"Generalizability beyond renal tubular cells untested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Positioned PARVB within the FSCN2/PPAR-\\u03b3 axis as a negative modulator of the ILK-AKT survival pathway in cochlear cells.\",\n      \"evidence\": \"Fscn2 knockout mouse, microarray, siRNA knockdown, overexpression rescue, PPAR-\\u03b3 inhibition, and Western blot of ILK/p-AKT/Bcl-2/Caspase9\",\n      \"pmids\": [\"38374196\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct biochemical reconstitution of a PARVB-ILK interaction\", \"Mechanism by which PARVB suppresses ILK activity unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified hypoxia as an upstream transcriptional driver of PARVB and tied its expression to tumor cell motility and growth.\",\n      \"evidence\": \"HIF-1\\u03b1/2\\u03b1 knockdown, promoter hypoxia-responsive element analysis, in vitro proliferation/migration/invasion assays, and melanoma xenograft\",\n      \"pmids\": [\"38301409\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct HIF binding to the PARVB promoter element not shown by ChIP\", \"Downstream effectors of PARVB in melanoma not defined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Confirmed PARVB as a functionally required driver of cell motility in a second cancer context.\",\n      \"evidence\": \"siRNA knockdown with migration and wound-healing assays in tongue squamous cell carcinoma cells\",\n      \"pmids\": [\"25422907\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No molecular pathway linking PARVB to migration in this model\", \"Single lab, related rather than orthogonal assays\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extended PARVB's pro-tumor role to additional contexts and candidate effector pathways (JAK2/STAT3 and EMT, PALB2-dependent macropinocytosis, and a SMAD3-TNFSF13 immunosuppressive axis).\",\n      \"evidence\": \"In vitro knockdown/overexpression, 3D spheroid and macropinocytosis assays, transcriptomic/scRNA-seq and multiplex IHC across glioblastoma, PALB2-mutated breast, and cervical cancer\",\n      \"pmids\": [\"34568031\", \"40730089\", \"40744226\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No direct biochemical validation of PARVB-JAK2/STAT3 or PARVB-SMAD3 interactions\", \"Mechanism placing PARVB downstream of PALB2 unresolved\", \"Pathway links inferred largely from transcriptomic/IHC correlation\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How PARVB integrates its distinct roles\\u2014ARHGEF6/GTPase scaffolding, TAK1 stabilization, and ILK-AKT modulation\\u2014into a unified mechanism, and which domains govern each, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of PARVB defining domain-specific partner binding\", \"Whether the survival and migration functions are mechanistically coupled is unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [1, 3]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"ARHGEF6\", \"TAK1\", \"ITCH\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":5,"faith_pct":80.0}}