{"gene":"VCP","run_date":"2026-06-11T09:02:06","timeline":{"discoveries":[{"year":2021,"finding":"The Cdc48/p97 ATPase complex with its cofactor Ufd1/Npl4 (UN) recognizes polyubiquitin chains (rather than the substrate directly), cooperatively binds the chain, unfolds one ubiquitin molecule (initiator), then pulls all ubiquitins linked to its C terminus through the central pore of the hexameric double ring, causing transient ubiquitin unfolding; when the ATPase reaches the isopeptide bond, it translocates and unfolds both N- and C-terminal substrate segments, while ubiquitins linked to the branchpoint dissociate from UN and move outside the pore, releasing unfolded polyubiquitinated substrate.","method":"In vitro reconstitution with purified yeast components, hydrogen–deuterium exchange MS, biochemical translocation assays, mutagenesis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstituted in vitro with purified components, multiple orthogonal methods (HDX-MS, translocation assays), mechanistic detail replicated in parallel work","pmids":["34951965"],"is_preprint":false},{"year":2024,"finding":"Bidirectional substrate shuttling between the 26S proteasome and the Cdc48-Ufd1/Npl4 ATPase complex promotes degradation of well-folded substrates. A minimal reconstituted system requires the 26S proteasome, Cdc48-UN complex, proteasome cofactor Rad23, and Cdc48 cofactors Ubx5 and Shp1: Rad23 and Ubx5 stimulate polyubiquitin binding to the proteasome and Cdc48-UN respectively, allowing competition for substrates; Shp1 stimulates protein unfolding by Cdc48-UN rather than substrate recruitment.","method":"In vitro reconstitution with purified yeast components, biochemical degradation assays, yeast genetics confirmation","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — full reconstitution with purified components plus in-vivo genetic confirmation, multiple orthogonal assays","pmids":["38401542"],"is_preprint":false},{"year":2022,"finding":"SUMO modification enhances substrate unfolding by the Ufd1/Npl4/Cdc48 complex: interactions between Ufd1 and SUMO accelerate unfolding of substrates modified by SUMO-polyubiquitin hybrid chains compared to polyubiquitin alone. Cryo-EM structures of the complex with a SUMO-polyubiquitin hybrid-chain substrate reveal features of Ufd1/Npl4/Cdc48 interactions with ubiquitin prior to and during unfolding.","method":"In vitro unfolding assays with purified yeast proteins, single-particle cryo-EM structural analysis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with structural validation by cryo-EM, single lab but two orthogonal methods","pmids":["36574706"],"is_preprint":false},{"year":2009,"finding":"VCP/p97 is required for autophagosome maturation: loss of VCP activity (by RNAi knockdown or dominant-negative overexpression) results in accumulation of immature autophagosomes under basal conditions; these autophagosomes fail to mature into autolysosomes and degrade LC3. Disease-causing IBMPFD mutants (R155H, A232E) cause the same autophagy defect. VCP is selectively required for autophagic degradation of ubiquitinated substrates but not for starvation-induced autophagy.","method":"RNAi knockdown, dominant-negative overexpression, stable dual-tagged LC3 reporter (mCherry-EGFP-LC3), patient-derived myoblasts","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (RNAi, dominant-negative, reporter assay, patient cells), replicated across labs in related papers","pmids":["20008565","20104022"],"is_preprint":false},{"year":2021,"finding":"VCP/p97 regulates autophagy initiation in two Beclin-1-dependent ways: (1) VCP stabilizes Beclin-1 protein levels by promoting the deubiquitinase activity of ataxin-3 (ATXN3) towards Beclin-1; (2) VCP interacts with and promotes assembly and kinase activity of the Beclin-1-containing PI3K complex I, regulating PI(3)P production. Inhibition of VCP ATPase activity impairs starvation-induced PI(3)P production and limits downstream recruitment of WIPI2, ATG16L, and LC3, decreasing autophagosome formation.","method":"Small-molecule VCP ATPase inhibitors, PI(3)P lipid assays, co-immunoprecipitation, deubiquitinase activity assays, WIPI2/ATG16L/LC3 recruitment assays","journal":"Nature chemical biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (inhibitors, co-IP, enzymatic assays, recruitment assays) in single rigorous study","pmids":["33510452","33719912"],"is_preprint":false},{"year":2011,"finding":"Cdc48/p97, together with cofactors Ufd1-Npl4, Ubx4, and Ubx5, mediates UV-dependent turnover of RNA Pol II largest subunit Rpb1: ubiquitinated Rpb1, proteasomes, and Cdc48 accumulate on chromatin in UV-treated cells; in cdc48 mutants, Ub conjugates accumulate on the proteasome, indicating Cdc48 acts to facilitate processive degradation at sites of stalled transcription rather than solely upstream of the proteasome.","method":"Proteasome isolation followed by mass spectrometry, chromatin fractionation, genetic mutant analysis in yeast","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (MS, fractionation, genetics), mechanistic model supported by epistasis data","pmids":["21211725"],"is_preprint":false},{"year":2005,"finding":"IBMPFD disease-causing VCP/p97 mutant R155H has normal ATPase activity and hexameric structure, yet impairs ERAD: it increases overall ubiquitin-conjugated proteins and specifically blocks degradation of the ERAD substrate ΔF508-CFTR, similar to ATPase-deficient VCP. IBMPFD mutants also promote formation of aggregates containing VCP, ubiquitin conjugates, and ER-resident proteins.","method":"Cell-based ERAD substrate degradation assays, ATPase activity measurement, native gel electrophoresis, immunofluorescence/co-localization in cultured cells","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (biochemical, cell-based substrate assays, structural analysis), single lab","pmids":["16321991"],"is_preprint":false},{"year":2011,"finding":"Cdc48/p97-Ufd1-Npl4 complex removes Aurora B from chromatin during mitotic exit in Xenopus egg extracts; in HeLa cells, Ufd1-Npl4 antagonizes Aurora B on chromosomes from prometaphase onwards. Depletion of Ufd1-Npl4 by siRNA causes increased Aurora B levels and activity on chromosomes, chromosome alignment and anaphase defects, and multi-lobed nuclei; low-dose Aurora B inhibitor partially rescues these defects.","method":"siRNA depletion, quantitative immunofluorescence, Aurora B kinase activity assay (CENP-A phosphorylation), genetic epistasis with hesperadin inhibitor in HeLa cells","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal genetic epistasis plus kinase activity readout, replicated across Xenopus and human cell systems","pmids":["21486945","20130676"],"is_preprint":false},{"year":2010,"finding":"In budding yeast, Cdc48-Shp1 complex promotes chromosome bi-orientation by facilitating nuclear localization of the phosphatase Glc7/PP1, which counteracts Ipl1/Aurora B kinase activity at kinetochores. Temperature-sensitive cdc48-3 and Shp1 depletion cause metaphase arrest due to defective bipolar kinetochore attachment and spindle checkpoint activation.","method":"Yeast temperature-sensitive mutants, co-immunoprecipitation, nuclear localization imaging, genetic epistasis with ipl1 mutants and kinase inhibitors","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with biochemical validation, mechanistic pathway clearly defined","pmids":["20483956"],"is_preprint":false},{"year":2018,"finding":"Cdc48/VCP promotes chromosome condensation by releasing condensin from chromatin entrapment via ubiquitin-dependent extraction. Condensin traps itself in its own reaction product during chromatin compaction; Cdc48 acts as the central segregase that promotes ubiquitin-dependent cycling of condensin on mitotic chromatin.","method":"Yeast genetics, in vivo chromatin binding assays, ubiquitin mutant epistasis, condensin-chromatin dynamics assays","journal":"Molecular cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo epistasis and chromatin binding assays, single lab, multiple genetic methods","pmids":["29452641"],"is_preprint":false},{"year":2013,"finding":"In yeast, stress granules can be targeted for autophagic degradation (granulophagy) in a process requiring CDC48/VCP. Genetic screen identified CDC48 alleles as affecting stress granule dynamics; in mammalian cells, depletion or pathogenic mutations in VCP reduce stress granule clearance, an effect also seen with autophagy inhibition.","method":"Yeast genetic screen (125 genes), fluorescence microscopy of stress granule dynamics, RNAi depletion, patient mutation expression in mammalian cells","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — unbiased genetic screen plus mechanistic validation in both yeast and mammalian cells with multiple methods","pmids":["23791177"],"is_preprint":false},{"year":2019,"finding":"ULK1 and ULK2 kinases phosphorylate VCP/p97, thereby increasing VCP's ATPase activity and its ability to disassemble stress granules. ULK1/2 localize to stress granules; disrupted ULK1/2 expression in mice causes a vacuolar myopathy similar to VCP disease with TDP-43-positive inclusions.","method":"Kinase phosphorylation assays, stress granule disassembly assays, VCP ATPase activity measurement, mouse knockout models, ULK1/2 agonist pharmacology","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vitro kinase assay plus ATPase activity measurement plus in vivo mouse model, multiple orthogonal methods","pmids":["30979586"],"is_preprint":false},{"year":2020,"finding":"A p.Asp395Gly mutation in VCP is associated with dementia characterized by neurofibrillary tangles. Wild-type VCP exhibits tau disaggregase activity in vitro, which is impaired by the p.Asp395Gly mutation. Intracerebral microinjection of pathologic tau into p.Asp395Gly VCP knock-in mice leads to increased tau aggregates compared to wild-type mice.","method":"In vitro tau disaggregation assay with purified VCP, VCP knock-in mouse model with intracerebral tau microinjection, neuropathological analysis","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro disaggregation assay with purified protein plus in vivo knock-in mouse model, two orthogonal methods","pmids":["33004675"],"is_preprint":false},{"year":2023,"finding":"In cell culture and neurons, VCP is recruited to ubiquitylated Tau fibrils and efficiently disaggregates them; aggregate clearance depends on functional cooperation of VCP with Hsp70 and the ubiquitin-proteasome machinery. Inhibition of VCP stabilizes large Tau aggregates, whereas VCP-mediated disaggregation generates seeding-active Tau species as a byproduct.","method":"Cell culture Tau aggregate clearance assays, VCP inhibitors, VCP depletion, live-cell imaging, seeding activity assays in neurons","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (inhibitors, depletion, live imaging, seeding assays), replicated in cells and neurons","pmids":["36732333"],"is_preprint":false},{"year":2017,"finding":"Endogenous VCP negatively regulates Mitofusin, which is required for outer mitochondrial membrane fusion. IBMPFD disease mutants of VCP act as hyperactive alleles with respect to Mitofusin regulation; VCP inhibitors suppress mitochondrial fusion and respiratory defects in IBMPFD patient fibroblasts and in a Drosophila IBMPFD muscle model.","method":"Drosophila in vivo IBMPFD muscle model, patient fibroblast assays, VCP inhibitor treatment, mitochondrial morphology/respiration assays","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo model plus patient cell validation, two orthogonal systems, single lab","pmids":["28322724"],"is_preprint":false},{"year":2016,"finding":"VCP, together with cofactor P47 and the ER morphology regulator ATL1, regulates tubular ER formation and controls protein synthesis efficiency to influence dendritic spine formation in neurons. Knockdown or disease mutation knockin of VCP reduces dendritic spine density; leucine supplementation (increasing protein synthesis) rescues spine defects caused by VCP deficiency.","method":"Knockdown, disease-mutation knockin mice, live imaging of ER morphology, protein synthesis measurement, dendritic spine morphometry in neurons","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple genetic approaches plus functional readouts in neurons, single lab","pmids":["26984393"],"is_preprint":false},{"year":2009,"finding":"VCP/p97 is highly modified by phosphorylation and acetylation at numerous sites throughout the protein. Amino acid substitutions at Lys696 and Thr761 (in the D2alpha/VAR domain) profoundly affect VCP ATPase activity, identifying this region as an ATPase regulatory domain. Lys251 and Lys524 (Walker A motifs of D1 and D2 domains) are potential acetylation sites.","method":"Mass spectrometry identification of modification sites, site-directed mutagenesis with ATPase activity measurement","journal":"Genes to cells : devoted to molecular & cellular mechanisms","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — mutagenesis with enzymatic assay, single lab, limited follow-up on regulatory consequences","pmids":["19335618"],"is_preprint":false},{"year":2011,"finding":"The UBX domain protein Ubx4 modulates the Cdc48-Ufd1-Npl4 complex for correct ERAD function. Ubx4 mutants defective in Cdc48 binding lead to defective degradation of ERAD substrates and accumulation of polyubiquitinated proteins bound to Cdc48. Ubx2 and Ubx4 are not found together in one Cdc48 complex, suggesting distinct steps in modulating Cdc48 activity in ERAD.","method":"Yeast genetics with ERAD substrate degradation assays, co-immunoprecipitation, polyubiquitin accumulation assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple genetic and biochemical approaches, single lab, clear substrate phenotype","pmids":["19359248"],"is_preprint":false},{"year":2018,"finding":"In budding yeast, defective RNA polymerase III (Pol III) is negatively regulated by a sequential SUMO–ubiquitin–Cdc48 pathway: Pol III is sumoylated, then ubiquitylated, and subsequently targeted by Cdc48/p97 segregase, leading to proteasomal degradation of Pol III subunits and repression of Pol III transcription.","method":"Yeast genetics, sumoylation and ubiquitylation assays, Cdc48 mutant analysis, proteasomal degradation assays","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic and biochemical epistasis, single lab, multiple modifications characterized","pmids":["30192228"],"is_preprint":false},{"year":2022,"finding":"WIPI2 binds VCP/p97 and promotes its recruitment to damaged mitochondria during PINK1-PRKN-mediated mitophagy. WIPI2 depletion blunts VCP recruitment to damaged mitochondria, leading to reduced degradation of outer mitochondrial membrane proteins and impaired mitophagy.","method":"Co-immunoprecipitation, RNAi depletion, mitophagy flux assays, OMM protein degradation assays, cell death assays","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP plus functional depletion assays with defined substrate readout, single lab","pmids":["35389758"],"is_preprint":false},{"year":2021,"finding":"VCP cofactor UBXN1/SAKS1 translocates to mitochondria upon depolarization in a PRKN-dependent manner and facilitates MFN2 removal from the outer mitochondrial membrane; loss of UBXN1 impairs VCP and PRKN translocation to mitochondria and reduces mitophagic flux. UBXN1 physically interacts with PRKN in a UBX domain-dependent manner.","method":"Co-immunoprecipitation, siRNA depletion, mitophagy flux assays, immunofluorescence imaging of mitochondrial translocation, domain mapping","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP with domain mapping plus functional depletion assays, single lab","pmids":["33966597"],"is_preprint":false},{"year":2022,"finding":"Polo-like kinase 1 (Plk1) phosphorylates VCP/p97 at Thr76, recruiting VCP to the centrosome from prophase to anaphase and regulating centrosome orientation. Dephosphorylation of Thr76 by PTEN is required for VCP and Eg5 enrichment at the mitotic spindle, ensuring proper spindle architecture and chromosome segregation. Cryo-EM structures of phosphomimetic (T76E) and phospho-deficient (T76A) VCP revealed that Thr76 phosphorylation alters inter-domain/inter-subunit interactions and the nucleotide-binding pocket conformation.","method":"Kinase assay, phospho-mutant cell biology, siRNA depletion, cryo-EM structural analysis, co-localization imaging, xenograft tumor growth assay","journal":"Cell death and differentiation","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay with structural cryo-EM validation and multiple cell-biology readouts, single lab with orthogonal methods","pmids":["35430615"],"is_preprint":false},{"year":2024,"finding":"VCP/p97 is UFMylated at K109 by the E3 ligase UFL1; this modification promotes BECN1 stabilization through ATXN3-mediated deubiquitination and facilitates assembly of the BECN1-containing PI3K complex, thereby promoting autophagy initiation. UFMylation-defective VCP mutant cannot rescue VCP depletion-induced LC3B accumulation. Several pathogenic VCP mutations are associated with reduced UFMylation.","method":"Mass spectrometry identification of UFMylation site, site-directed mutagenesis, co-immunoprecipitation, BECN1 stability assays, LC3B reporter assays","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — MS site identification plus mutagenesis plus functional rescue assays, single lab","pmids":["38762759"],"is_preprint":false},{"year":2023,"finding":"DUSP1 phosphatase interacts with VCP on mitochondria and dephosphorylates VCP at Ser784. LPS-induced endotoxemia promotes VCP Ser784 phosphorylation; DUSP1 overexpression prevents this, preserving mitochondrial quality control. A phosphomimetic VCP S784E mutant abolishes DUSP1's protective effects on mitochondrial dynamics, mitophagy, and cardiomyocyte contractility.","method":"Co-immunoprecipitation, phospho-specific antibodies, site-directed mutagenesis (phosphomimetic), DUSP1 transgenic mice and HL-1 cell transfection, mitochondrial function assays","journal":"Cellular and molecular life sciences : CMLS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus mutagenesis plus in vivo transgenic model, single lab, multiple readouts","pmids":["37464072"],"is_preprint":false},{"year":2022,"finding":"PTP4A2 phosphatase dephosphorylates VCP/p97 at Tyr805; this dephosphorylation enables VCP to associate with its C-terminal cofactors UBXN6/UBXD1 and PLAA, which are components of the ELDR complex responsible for lysophagy (autophagic clearance of damaged lysosomes). Loss of PTP4A2 compromises recovery from acute kidney injury due to impaired lysophagy.","method":"Substrate trapping and mass spectrometry, biochemical dephosphorylation assays, co-immunoprecipitation, lysophagy assays, Ptp4a2 knockout mice","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 1 / Moderate — unbiased substrate trapping + MS identification + biochemical validation + in vivo knockout model, multiple orthogonal methods, single lab","pmids":["36300783"],"is_preprint":false},{"year":2021,"finding":"VCP's cofactor FAF1 facilitates VCP-dependent extraction of SUMOylated and ubiquitylated proteins accumulating on chromatin after DNA replication blocks; this VCP(FAF1) activity cooperates with the deubiquitylase USP7 (which maintains a SUMO-high/ubiquitin-low environment at active replication forks). Inactivation of USP7 and FAF1 is synthetically lethal in C. elegans and mammalian cells.","method":"Co-immunoprecipitation, chromatin fractionation, C. elegans and mammalian cell genetics, synthetic lethality assays, VCP and USP7 inhibitor synergy","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis plus biochemical chromatin fractionation, replicated from worm to mammalian cells, single main lab","pmids":["34644576"],"is_preprint":false},{"year":2023,"finding":"The p97/VCP UFD1-NPLOC4 segregase complex is required for arsenic-induced degradation of PML and PML-RARA. p97/VCP localizes to PML bodies after arsenic treatment; pharmacological p97 inhibition or siRNA depletion of UFD1/NPLOC4 blocks arsenic-induced degradation of PML-RARA, accumulates SUMO- and ubiquitin-modified PML, and alters PML body number, morphology, and size.","method":"Proteomic analysis of PML bodies, pharmacological p97 inhibition, siRNA depletion, immunofluorescence, biochemical PML modification analysis","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (proteomics, inhibitors, siRNA, imaging), single lab","pmids":["36880596"],"is_preprint":false},{"year":2024,"finding":"Inhibited WRN helicase is trapped on chromatin and requires p97/VCP for extraction and proteasomal degradation in microsatellite-instability-high (MSI-H) cancer cells. The PIAS4-RNF4 SUMO-ubiquitin axis is responsible for generating the SUMOylated/ubiquitylated WRN signal recognized by p97/VCP for chromatin extraction.","method":"Single-molecule tracking in living cells, pharmacological WRN inhibition, p97 inhibition, PIAS4 and RNF4 genetic epistasis, chromatin fractionation","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — single-molecule tracking plus genetic epistasis plus biochemical fractionation, single lab, novel method combination","pmids":["39025847"],"is_preprint":false},{"year":2023,"finding":"Ubx5-Cdc48 assists the protease Wss1 in clearing DNA-protein crosslinks (DPCs): Ubx5 accumulates at persistent DPC lesions in the absence of Wss1; abolishing Cdc48 binding by Ubx5 or complete Ubx5 loss suppresses wss1Δ sensitivity to DPC-inducing agents by favoring alternate repair pathways. Ubx5-Cdc48 and Wss1 cooperate in genotoxin-induced degradation of RNA Pol II at DPC lesions.","method":"Yeast genetics, inducible site-specific crosslink assay, chromatin immunoprecipitation, genetic epistasis, RNAPII degradation assays","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple genetic and biochemical approaches with inducible model system, single lab","pmids":["37144685"],"is_preprint":false},{"year":1993,"finding":"VCP forms a stoichiometric complex with clathrin and Hsc70 in mammalian cell lysates within 15 min of synthesis, identifying VCP as a ubiquitous clathrin-binding protein and suggesting a role in modulating protein-protein interactions in membrane transport processes.","method":"Biochemical co-purification, co-immunoprecipitation, stoichiometric complex analysis from mammalian cell lysates","journal":"Nature","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-purification/co-IP establishing complex formation, no functional mechanism assayed, replicated in multiple cell types","pmids":["8413590"],"is_preprint":false},{"year":2012,"finding":"Both Cdc48 and its cofactor Vms1 (but not Ufd1 or Ufd2) are required for degradation of the telomere regulator Cdc13; this degradation involves both autophagy and the proteasome under non-stress conditions.","method":"Yeast deletion mutant analysis, Cdc13 stability assays, autophagy and proteasome inhibition genetics","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with defined substrate, single lab, multiple pathway interrogation","pmids":["22718752"],"is_preprint":false},{"year":2013,"finding":"In IBMPFD, all twelve pathogenic p97/VCP missense mutants cause ERAD substrate accumulation. Most IBMPFD mutants show enhanced binding to cofactors p47 and Ufd1-Npl4. However, the P137L mutant uniquely abolishes interactions with Ufd1, Npl4, and p47 while retaining gp78-VIM binding, and shows a distinct solubility profile and subcellular localization compared to other IBMPFD mutants.","method":"ERAD substrate degradation assays, in vitro protein-protein binding assays with recombinant proteins, co-immunoprecipitation, subcellular fractionation, immunofluorescence","journal":"The international journal of biochemistry & cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple methods (in vitro binding, co-IP, cell assays, fractionation), single lab, comprehensive mutant panel","pmids":["23333620"],"is_preprint":false},{"year":2015,"finding":"An ALS-disease-associated aspartate mutation in the pore-2 loop of the D2 ring of Cdc48/p97 impairs 20S proteasome binding and proteolytic communication but does not affect hexamer stability, ATP hydrolysis rate, or protein unfolding activity, identifying the pore-2 loop as a critical element for direct Cdc48–20S proteasome interaction.","method":"In vitro binding assays between purified archaeal/human Cdc48 variants and 20S proteasome, ATPase activity measurement, protein unfolding assays, hexamer stability analysis, site-directed mutagenesis","journal":"Protein science : a publication of the Protein Society","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro biochemical reconstitution with mutagenesis, single lab, multiple functional readouts","pmids":["26134898"],"is_preprint":false},{"year":2014,"finding":"Archaeal Cdc48 and 20S proteasome form a stable, enzymatically active coaxial complex stabilized by site-specific cross-linking. The N-terminal domain of Cdc48 packs against the D1 ring in a coplanar fashion in this complex, and the structure demonstrates that coaxial alignment without AAA+ wobbling is sufficient for function.","method":"Site-specific chemical cross-linking, single-particle electron microscopy structure determination, in vitro proteolytic activity assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Moderate — EM structure with biochemical reconstitution and activity validation, single study","pmids":["24711419"],"is_preprint":false},{"year":2019,"finding":"VCP inactivation in skeletal muscle of adult mice (conditional knockout) causes lysosomal membrane damage, persistent TFEB nuclear localization, and a necrotic myopathy distinct from ATG5 knockout, identifying VCP as a central mediator of both lysosomal clearance and TFEB-regulated lysosomal biogenesis in differentiated muscle.","method":"Conditional muscle-specific knockout mice, lysosomal damage markers (LGALS3), TFEB localization by immunofluorescence, comparison with ATG5 knockout mice, chemical lysosomal membrane permeabilization","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional knockout mouse model plus multiple cellular readouts, comparison with another autophagy gene knockout as control, single lab","pmids":["30654731"],"is_preprint":false},{"year":2023,"finding":"Nuclear VCP binds to HDAC1 and facilitates its degradation, thereby promoting transcription of FAO genes including CPT1A, upregulating fatty acid oxidation in colorectal cancer cells.","method":"Co-immunoprecipitation, VCP inhibitor and knockdown experiments, chromatin-based transcription assays, HDAC1 stability assays, cancer cell functional assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus functional knockdown/inhibitor assays with transcriptional readout, single lab","pmids":["37788309"],"is_preprint":false},{"year":2025,"finding":"VCP is a top hit in a proximity-labeling screen for proteins that control tau seed amplification within 5 h of seed exposure. VCP knockdown reduces tau seeding; two VCP inhibitors (ML-240 and NMS-873) have opposing effects on seeding, with effects only observed within 8 h of seed exposure. Screening 30 VCP cofactors identified ATXN3, NSFL1C, UBE4B, NGLY1, OTUB1, and NPLOC4 as suppressors of tau seeding, while FAF2 reduction increases seeding.","method":"Split-APEX2 proximity labeling screen, CRISPR/siRNA cofactor screen, tau seeding biosensor assays in HEK293T cells and human neurons, VCP inhibitor pharmacology","journal":"Molecular neurodegeneration","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — unbiased proximity screen plus cofactor epistasis screen plus pharmacology, single lab, multiple complementary methods","pmids":["39773263"],"is_preprint":false},{"year":2021,"finding":"Neuronal VCP loss of function (conditional knockout in postnatal forebrain neurons) causes cortical atrophy, neuronal loss, autophagolysosomal dysfunction, and TDP-43 inclusions resembling FTLD-TDP pathology. A single disease-associated VCP-R155C mutation in a VCP null background similarly recapitulates VCP inactivation features, suggesting the R155C MSP mutation is hypomorphic (loss-of-function rather than dominant-negative).","method":"Conditional neuronal knockout mice, VCP-R155C knock-in in null background, transcriptomic and proteomic analysis, TDP-43 immunohistochemistry","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional knockout mouse model with genetic epistasis (rescue by single mutant allele), single lab","pmids":["34289347"],"is_preprint":false}],"current_model":"VCP/p97 (CDC48) is a hexameric AAA+ ATPase that uses ATP hydrolysis—primarily in the D2 domain—to thread polyubiquitinated client proteins through its central pore, unfolding substrates and extracting them from membranes, protein complexes, and chromatin; it acts together with a large network of cofactors (principally Ufd1-Npl4 for ubiquitin-modified substrates, and SEP-domain adaptors for ubiquitin-independent targeting) to deliver clients to the proteasome or autophagy pathway, and it additionally regulates autophagy initiation via Beclin-1 stabilization (through ATXN3 deubiquitinase activity) and PI3K complex assembly, stress granule disassembly (activated by ULK1/2-mediated phosphorylation), chromosome segregation (by removing Aurora B from chromatin), ERAD retrotranslocation, tau/aggregate disaggregation, and mitochondrial quality control, with its activity further tuned by post-translational modifications including phosphorylation (Thr76 by Plk1/PTEN; Ser784 by DUSP1; Tyr805 by PTP4A2), acetylation, and UFMylation (K109 by UFL1)."},"narrative":{"mechanistic_narrative":"VCP/p97 (yeast Cdc48) is a hexameric AAA+ ATPase segregase that uses ATP hydrolysis to extract and unfold ubiquitinated client proteins from membranes, chromatin, and protein complexes, delivering them to the proteasome or autophagy machinery [PMID:34951965, PMID:38401542]. With its core cofactor Ufd1-Npl4, VCP cooperatively engages polyubiquitin chains rather than the substrate directly, unfolds an initiator ubiquitin, and threads the linked chain and substrate segments through its central pore [PMID:34951965]; SUMO-polyubiquitin hybrid chains accelerate this unfolding through Ufd1-SUMO contacts [PMID:36574706]. Substrate handoff to the 26S proteasome is bidirectional and depends on adaptor cofactors (Rad23, Ubx5/Shp1) that partition polyubiquitin binding and stimulate unfolding [PMID:38401542], and direct Cdc48-20S coaxial coupling occurs through the D2-ring pore-2 loop [PMID:26134898, PMID:24711419]. VCP performs ubiquitin-dependent chromatin extraction across diverse contexts: removing Aurora B during mitotic exit [PMID:21486945, PMID:20130676], cycling condensin during chromosome condensation [PMID:29452641], degrading stalled/damaged RNA polymerases [PMID:21211725, PMID:30192228], and extracting SUMO-ubiquitin-marked factors at replication forks and DNA-protein crosslinks (FAF1, Ubx5/Wss1) [PMID:34644576, PMID:37144685]. VCP is also central to protein quality control: it drives ERAD retrotranslocation [PMID:16321991, PMID:19359248], stress-granule disassembly upon ULK1/2 phosphorylation [PMID:23791177, PMID:30979586], lysosomal clearance and TFEB-regulated lysosomal biogenesis [PMID:30654731], mitochondrial quality control via Mitofusin/MFN2 removal and PINK1-PRKN mitophagy [PMID:28322724, PMID:35389758, PMID:33966597], and Hsp70-assisted disaggregation of ubiquitylated tau fibrils [PMID:33004675, PMID:36732333]. VCP additionally regulates autophagy initiation by stabilizing Beclin-1 through ATXN3 deubiquitinase activity and promoting PI3K complex I assembly [PMID:33510452, PMID:33719912]. Its activity is tuned by post-translational modifications including UFMylation at K109 by UFL1 [PMID:38762759], phosphorylation at Thr76 (Plk1/PTEN), Ser784 (DUSP1), and Tyr805 (PTP4A2, gating UBXD1/PLAA-dependent lysophagy) [PMID:35430615, PMID:37464072, PMID:36300783], and acetylation [PMID:19335618]. Disease-causing IBMPFD/MSP and dementia mutations (R155H, A232E, R155C, D395G) impair ERAD, autophagosome maturation, and tau disaggregation, establishing VCP as causal in multisystem proteinopathy and tauopathy [PMID:20008565, PMID:20104022, PMID:16321991, PMID:33004675, PMID:34289347].","teleology":[{"year":1993,"claim":"Established VCP's first physical association in membrane traffic, showing it stoichiometrically binds clathrin and Hsc70 and might modulate protein-protein interactions in transport.","evidence":"Biochemical co-purification and co-immunoprecipitation from mammalian cell lysates","pmids":["8413590"],"confidence":"Medium","gaps":["No functional mechanism assayed","Role of ATPase activity in clathrin/Hsc70 complex not tested"]},{"year":2005,"claim":"Linked IBMPFD disease mutations to a loss of ERAD function, showing R155H impairs degradation of an ERAD substrate despite normal ATPase activity and hexamer structure.","evidence":"Cell-based ERAD substrate degradation assays, ATPase measurement, native gel, immunofluorescence","pmids":["16321991"],"confidence":"High","gaps":["Molecular basis of substrate-handling defect with intact ATPase unresolved","Did not establish whether mutation is gain or loss of function"]},{"year":2009,"claim":"Defined VCP as required for autophagosome maturation, distinguishing ubiquitin-dependent autophagy of substrates from starvation-induced autophagy and tying disease mutants to the defect.","evidence":"RNAi, dominant-negative overexpression, mCherry-EGFP-LC3 reporter, patient myoblasts","pmids":["20008565","20104022"],"confidence":"High","gaps":["Did not resolve which maturation step VCP acts on","Cofactor requirements not defined"]},{"year":2009,"claim":"Mapped VCP as heavily phosphorylated/acetylated and identified a D2alpha/VAR regulatory region controlling ATPase activity.","evidence":"Mass spectrometry of modification sites plus site-directed mutagenesis with ATPase assays","pmids":["19335618"],"confidence":"Medium","gaps":["Physiological enzymes and consequences of most modifications not established","Limited follow-up on regulatory outcomes"]},{"year":2011,"claim":"Extended VCP function to chromatin, showing it acts at sites of stalled transcription to facilitate processive proteasomal degradation of ubiquitinated Rpb1 after UV.","evidence":"Proteasome isolation/MS, chromatin fractionation, yeast genetics","pmids":["21211725"],"confidence":"High","gaps":["Precise extraction step at chromatin not visualized","Generalization beyond Pol II unclear at the time"]},{"year":2010,"claim":"Connected VCP to chromosome bi-orientation via Cdc48-Shp1-driven nuclear localization of PP1, counteracting Aurora B at kinetochores.","evidence":"Yeast ts mutants, co-IP, localization imaging, genetic epistasis with ipl1","pmids":["20483956"],"confidence":"High","gaps":["Direct substrate of Cdc48 in this pathway not identified","Conservation to human kinetochores not tested here"]},{"year":2011,"claim":"Demonstrated direct Cdc48-Ufd1-Npl4 removal of Aurora B from chromatin during mitotic exit across Xenopus and human systems, defining a mitotic role for the segregase.","evidence":"siRNA, quantitative IF, Aurora B kinase activity assay, epistasis with hesperadin","pmids":["21486945","20130676"],"confidence":"High","gaps":["Whether Aurora B is a direct VCP substrate not shown biochemically","Ubiquitin ligase upstream unidentified"]},{"year":2011,"claim":"Showed the UBX cofactor Ubx4 modulates Cdc48-Ufd1-Npl4 for ERAD, defining distinct cofactor-dependent steps in substrate handling.","evidence":"Yeast genetics, ERAD substrate assays, co-IP, polyubiquitin accumulation","pmids":["19359248"],"confidence":"Medium","gaps":["Mechanistic step controlled by Ubx4 vs Ubx2 not fully defined","Mammalian relevance untested"]},{"year":2012,"claim":"Identified a Vms1-dependent, Ufd1/Ufd2-independent Cdc48 route degrading the telomere regulator Cdc13 via both autophagy and proteasome.","evidence":"Yeast deletion mutants, Cdc13 stability assays, pathway inhibition genetics","pmids":["22718752"],"confidence":"Medium","gaps":["Direct extraction mechanism not shown","Choice between autophagy and proteasome unexplained"]},{"year":2013,"claim":"Established granulophagy, a CDC48/VCP-dependent autophagic clearance of stress granules conserved from yeast to mammals and sensitive to disease mutations.","evidence":"Unbiased yeast genetic screen, fluorescence microscopy, RNAi, patient mutation expression","pmids":["23791177"],"confidence":"High","gaps":["Substrate within stress granules targeted by VCP unidentified","Trigger for VCP recruitment unclear"]},{"year":2013,"claim":"Characterized a comprehensive IBMPFD mutant panel, showing all cause ERAD substrate accumulation and most enhance Ufd1-Npl4/p47 binding, with P137L as a distinct cofactor-binding-deficient outlier.","evidence":"ERAD assays, in vitro binding, co-IP, fractionation, IF","pmids":["23333620"],"confidence":"Medium","gaps":["How enhanced cofactor binding causes dysfunction not resolved","Functional uniqueness of P137L mechanistically unexplained"]},{"year":2014,"claim":"Provided structural proof that Cdc48 and the 20S proteasome form a stable coaxial complex, showing coplanar N-D1 packing is sufficient for function.","evidence":"Site-specific cross-linking, single-particle EM, in vitro proteolysis (archaeal)","pmids":["24711419"],"confidence":"High","gaps":["Relevance of archaeal coupling to eukaryotic 26S not established","Substrate handoff geometry not resolved"]},{"year":2015,"claim":"Pinpointed the D2-ring pore-2 loop as the element mediating Cdc48-20S interaction, separating proteasome communication from unfolding/ATPase activity, and linked an ALS mutation to this surface.","evidence":"In vitro binding of purified Cdc48 variants and 20S, ATPase, unfolding, hexamer stability assays","pmids":["26134898"],"confidence":"Medium","gaps":["In-cell consequence of impaired 20S coupling not measured","Disease mechanism in neurons not tested"]},{"year":2016,"claim":"Revealed a neuronal role for VCP-p47-ATL1 in tubular ER formation and protein synthesis controlling dendritic spine density, with rescue by leucine.","evidence":"Knockdown, disease-mutation knockin mice, ER live imaging, protein synthesis and spine morphometry","pmids":["26984393"],"confidence":"Medium","gaps":["Direct VCP substrate linking ER shape to translation unknown","Single lab"]},{"year":2017,"claim":"Identified Mitofusin as a target negatively regulated by VCP, with IBMPFD mutants as hyperactive alleles suppressible by VCP inhibitors in patient and fly models.","evidence":"Drosophila IBMPFD muscle model, patient fibroblasts, VCP inhibitors, mitochondrial morphology/respiration","pmids":["28322724"],"confidence":"Medium","gaps":["Direct extraction of Mitofusin not biochemically reconstituted","Cofactor dependence unclear"]},{"year":2018,"claim":"Defined a sequential SUMO-ubiquitin-Cdc48 pathway degrading defective RNA Pol III, broadening VCP's transcriptional quality-control role.","evidence":"Yeast genetics, sumoylation/ubiquitylation assays, Cdc48 mutant and degradation analysis","pmids":["30192228"],"confidence":"Medium","gaps":["Ligases and recognition determinants partially defined","Mammalian conservation untested"]},{"year":2018,"claim":"Showed Cdc48 acts as the segregase releasing self-entrapped condensin from chromatin to enable chromosome condensation.","evidence":"Yeast genetics, chromatin binding assays, ubiquitin mutant epistasis","pmids":["29452641"],"confidence":"Medium","gaps":["Direct condensin ubiquitination/extraction not biochemically reconstituted","Single lab"]},{"year":2019,"claim":"Demonstrated ULK1/2 phosphorylate VCP to boost its ATPase activity and stress-granule disassembly, linking the kinases to VCP-disease-like myopathy with TDP-43 inclusions.","evidence":"Kinase assays, SG disassembly assays, VCP ATPase measurement, mouse knockouts, ULK agonists","pmids":["30979586"],"confidence":"High","gaps":["Phosphosite(s) and structural mechanism of activation not mapped here","Substrate extracted from SGs unidentified"]},{"year":2019,"claim":"Established VCP as a central mediator of lysosomal clearance and TFEB-regulated lysosomal biogenesis in adult muscle, causing a necrotic myopathy distinct from ATG5 loss.","evidence":"Conditional muscle knockout mice, lysosomal damage markers, TFEB localization, ATG5-KO comparison","pmids":["30654731"],"confidence":"High","gaps":["Molecular substrate at damaged lysosomes not defined here","Link to TFEB regulation mechanistically open"]},{"year":2020,"claim":"Identified VCP as a tau disaggregase whose activity is impaired by a dementia-associated D395G mutation, directly linking VCP to neurofibrillary tangle pathology.","evidence":"In vitro tau disaggregation with purified VCP, D395G knock-in mice with intracerebral tau injection","pmids":["33004675"],"confidence":"High","gaps":["Cofactor requirements for in vivo disaggregation not defined here","Fate of disaggregated tau unresolved"]},{"year":2021,"claim":"Resolved the core unfolding mechanism: Cdc48-Ufd1/Npl4 recognizes the polyubiquitin chain, unfolds an initiator ubiquitin, and threads chain plus substrate through the pore to release unfolded client.","evidence":"In vitro reconstitution with purified yeast components, HDX-MS, translocation assays, mutagenesis","pmids":["34951965"],"confidence":"High","gaps":["Cofactor-specific modulation of this cycle not fully mapped","Membrane-embedded substrate extraction not addressed"]},{"year":2021,"claim":"Defined a dual mechanism for VCP in autophagy initiation: stabilizing Beclin-1 via ATXN3 deubiquitination and promoting PI3K complex I assembly and PI(3)P production.","evidence":"VCP ATPase inhibitors, PI(3)P assays, co-IP, DUB activity, WIPI2/ATG16L/LC3 recruitment","pmids":["33510452","33719912"],"confidence":"High","gaps":["Whether VCP directly extracts a ubiquitin from Beclin-1 unresolved","Structural basis of PI3K-complex assembly role unknown"]},{"year":2021,"claim":"Defined VCP(FAF1) chromatin extraction of SUMO/ubiquitin-modified proteins at blocked replication forks, cooperating with USP7 in a synthetic-lethal relationship.","evidence":"Co-IP, chromatin fractionation, C. elegans and mammalian genetics, synthetic lethality, inhibitor synergy","pmids":["34644576"],"confidence":"Medium","gaps":["Identity of extracted fork-associated substrates partial","Single main lab"]},{"year":2021,"claim":"Established UBXN1/SAKS1 as the cofactor coupling VCP to PRKN-dependent mitophagy, facilitating MFN2 removal from the OMM.","evidence":"Co-IP, siRNA, mitophagy flux, IF translocation, domain mapping","pmids":["33966597"],"confidence":"Medium","gaps":["Direct extraction of MFN2 by VCP not reconstituted","Single lab"]},{"year":2021,"claim":"Showed neuronal VCP loss recapitulates FTLD-TDP pathology and that disease mutant R155C behaves as a hypomorphic loss-of-function allele.","evidence":"Conditional neuronal knockout mice, R155C knock-in in null background, omics, TDP-43 IHC","pmids":["34289347"],"confidence":"Medium","gaps":["Whether all MSP mutations are loss-of-function not generalized","Molecular driver of TDP-43 inclusions unclear"]},{"year":2022,"claim":"Showed SUMO modification of substrates accelerates VCP-mediated unfolding via Ufd1-SUMO contacts, with cryo-EM capturing the hybrid-chain engaged complex.","evidence":"In vitro unfolding with purified yeast proteins, single-particle cryo-EM","pmids":["36574706"],"confidence":"High","gaps":["Generality of SUMO acceleration across substrates unclear","Physiological SUMO-Ub hybrid substrates in cells not enumerated"]},{"year":2022,"claim":"Defined Plk1 phosphorylation of VCP at Thr76 (reversed by PTEN) as a switch positioning VCP at the centrosome versus spindle, with cryo-EM showing nucleotide-pocket conformational changes.","evidence":"Kinase assay, phospho-mutant cell biology, siRNA, cryo-EM, co-localization, xenograft","pmids":["35430615"],"confidence":"High","gaps":["Substrates extracted at centrosome/spindle not identified","Single lab"]},{"year":2022,"claim":"Established WIPI2 as the factor recruiting VCP to damaged mitochondria during PINK1-PRKN mitophagy for OMM protein degradation.","evidence":"Co-IP, RNAi, mitophagy flux, OMM degradation, cell death assays","pmids":["35389758"],"confidence":"Medium","gaps":["Mechanism of WIPI2-VCP coupling structurally undefined","Single lab"]},{"year":2022,"claim":"Showed PTP4A2 dephosphorylation of VCP at Tyr805 enables binding of C-terminal cofactors UBXD1/PLAA (ELDR complex) for lysophagy, with in vivo relevance to kidney injury recovery.","evidence":"Substrate trapping/MS, dephosphorylation assays, co-IP, lysophagy assays, Ptp4a2-KO mice","pmids":["36300783"],"confidence":"High","gaps":["Kinase that phosphorylates Tyr805 unidentified","Direct lysophagy substrate of VCP not defined"]},{"year":2023,"claim":"Showed VCP disaggregates ubiquitylated tau fibrils in neurons in cooperation with Hsp70 and the ubiquitin-proteasome system, but generates seeding-active byproducts.","evidence":"Cell/neuron clearance assays, VCP inhibitors, depletion, live imaging, seeding assays","pmids":["36732333"],"confidence":"High","gaps":["Determinants partitioning clearance versus seed generation unclear","In vivo relevance of seeding byproducts untested"]},{"year":2023,"claim":"Identified DUSP1-mediated dephosphorylation of VCP at Ser784 as preserving mitochondrial quality control during endotoxemia in cardiomyocytes.","evidence":"Co-IP, phospho-antibodies, phosphomimetic mutagenesis, DUSP1 transgenic mice, HL-1 cells, mitochondrial assays","pmids":["37464072"],"confidence":"Medium","gaps":["Kinase phosphorylating Ser784 not identified","Structural effect of Ser784 modification unknown"]},{"year":2023,"claim":"Showed nuclear VCP degrades HDAC1 to drive transcription of fatty-acid-oxidation genes (CPT1A) in colorectal cancer, defining a transcriptional/metabolic role.","evidence":"Co-IP, VCP inhibitor/knockdown, transcription assays, HDAC1 stability, cancer functional assays","pmids":["37788309"],"confidence":"Medium","gaps":["Ubiquitin-dependence of HDAC1 extraction not fully defined","Cofactor involvement unknown"]},{"year":2023,"claim":"Defined VCP-UFD1-NPLOC4 as required for arsenic-induced degradation of PML/PML-RARA at PML bodies, recognizing SUMO/ubiquitin-modified PML.","evidence":"PML-body proteomics, p97 inhibition, siRNA, IF, PML modification analysis","pmids":["36880596"],"confidence":"Medium","gaps":["Direct extraction kinetics not measured","Single lab"]},{"year":2023,"claim":"Showed Ubx5-Cdc48 assists Wss1 protease in clearing DNA-protein crosslinks and degrading RNA Pol II at lesions, defining a genotoxin-induced DPC repair role.","evidence":"Yeast genetics, inducible crosslink system, ChIP, epistasis, RNAPII degradation","pmids":["37144685"],"confidence":"Medium","gaps":["Mammalian conservation untested","Order of Cdc48 versus Wss1 action partial"]},{"year":2024,"claim":"Resolved bidirectional substrate shuttling between the 26S proteasome and Cdc48-UN, defining cofactor roles (Rad23, Ubx5, Shp1) in partitioning polyubiquitin binding and stimulating unfolding.","evidence":"Minimal in vitro reconstitution with purified yeast components, degradation assays, yeast genetics","pmids":["38401542"],"confidence":"High","gaps":["Regulatory logic determining handoff direction in cells unclear","Mammalian cofactor equivalents not tested"]},{"year":2024,"claim":"Identified UFMylation of VCP at K109 by UFL1 as a modification promoting BECN1 stabilization, PI3K complex assembly, and autophagy initiation, linking pathogenic mutations to reduced UFMylation.","evidence":"MS site ID, mutagenesis, co-IP, BECN1 stability and LC3B reporter assays","pmids":["38762759"],"confidence":"Medium","gaps":["Structural consequence of K109 UFMylation unknown","How UFMylation affects ATPase cycle untested"]},{"year":2024,"claim":"Showed inhibited WRN helicase is extracted by p97/VCP for degradation in MSI-H cancer cells via a PIAS4-RNF4 SUMO-ubiquitin signal, extending segregase function to a synthetic-lethal vulnerability.","evidence":"Single-molecule tracking, WRN/p97 inhibition, PIAS4/RNF4 epistasis, chromatin fractionation","pmids":["39025847"],"confidence":"Medium","gaps":["Cofactors mediating WRN extraction not defined","Single lab"]},{"year":2025,"claim":"Identified VCP and a defined set of its cofactors as controllers of tau seed amplification, with opposing inhibitor effects and cofactor-specific suppression/enhancement of seeding.","evidence":"Split-APEX2 proximity labeling, CRISPR/siRNA cofactor screen, tau seeding biosensors, inhibitor pharmacology","pmids":["39773263"],"confidence":"Medium","gaps":["Mechanism distinguishing suppressor versus enhancer cofactors unresolved","Why two inhibitors act oppositely unexplained"]},{"year":null,"claim":"How VCP's full cofactor network and post-translational modification code combine to dictate substrate choice, the clearance-versus-seeding outcome of aggregate disaggregation, and the unified mechanism by which disease mutations span ERAD, autophagy, mitochondrial, and tau pathologies remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No single framework reconciles loss-of-function versus hyperactive disease-mutant behaviors","Substrate-selection logic across the cofactor repertoire not systematically defined","Structural basis for most regulatory PTMs unmapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[0,1,2,16,21,32]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,12,13]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[4,7,9,14]},{"term_id":"GO:0140313","term_label":"molecular sequestering activity","supporting_discovery_ids":[5,7,25,27]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[5,7,25,35]},{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[5,7,9,25,27,28]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[6,15,17]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[14,19,20,23]},{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[21]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0,10]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,1,6,17,32]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[3,4,10,19,22,24,34]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[7,8,9,21]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[25,27,28]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[5,18,35]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[3,6,12,37]}],"complexes":["Cdc48-Ufd1-Npl4 (VCP-UFD1-NPLOC4) segregase","Cdc48-20S proteasome coaxial complex","VCP-clathrin-Hsc70 complex","ELDR lysophagy complex (VCP-UBXD1-PLAA)"],"partners":["UFD1","NPLOC4","ATXN3","FAF1","UBXN1","WIPI2","UFL1","HDAC1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P55072","full_name":"Transitional endoplasmic reticulum ATPase","aliases":["15S Mg(2+)-ATPase p97 subunit","Valosin-containing protein","VCP"],"length_aa":806,"mass_kda":89.3,"function":"Necessary for the fragmentation of Golgi stacks during mitosis and for their reassembly after mitosis. Involved in the formation of the transitional endoplasmic reticulum (tER). The transfer of membranes from the endoplasmic reticulum to the Golgi apparatus occurs via 50-70 nm transition vesicles which derive from part-rough, part-smooth transitional elements of the endoplasmic reticulum (tER). Vesicle budding from the tER is an ATP-dependent process. The ternary complex containing UFD1, VCP and NPLOC4 binds ubiquitinated proteins and is necessary for the export of misfolded proteins from the ER to the cytoplasm, where they are degraded by the proteasome. The NPLOC4-UFD1-VCP complex regulates spindle disassembly at the end of mitosis and is necessary for the formation of a closed nuclear envelope. Regulates E3 ubiquitin-protein ligase activity of RNF19A. Component of the VCP/p97-AMFR/gp78 complex that participates in the final step of the sterol-mediated ubiquitination and endoplasmic reticulum-associated degradation (ERAD) of HMGCR. Mediates the endoplasmic reticulum-associated degradation of CHRNA3 in cortical neurons as part of the STUB1-VCP-UBXN2A complex (PubMed:26265139). Involved in endoplasmic reticulum stress-induced pre-emptive quality control, a mechanism that selectively attenuates the translocation of newly synthesized proteins into the endoplasmic reticulum and reroutes them to the cytosol for proteasomal degradation (PubMed:26565908). Involved in clearance process by mediating G3BP1 extraction from stress granules (PubMed:29804830, PubMed:34739333). Also involved in DNA damage response: recruited to double-strand breaks (DSBs) sites in a RNF8- and RNF168-dependent manner and promotes the recruitment of TP53BP1 at DNA damage sites (PubMed:22020440, PubMed:22120668). Recruited to stalled replication forks by SPRTN: may act by mediating extraction of DNA polymerase eta (POLH) to prevent excessive translesion DNA synthesis and limit the incidence of mutations induced by DNA damage (PubMed:23042605, PubMed:23042607). Together with SPRTN metalloprotease, involved in the repair of covalent DNA-protein cross-links (DPCs) during DNA synthesis (PubMed:32152270). Involved in interstrand cross-link repair in response to replication stress by mediating unloading of the ubiquitinated CMG helicase complex (By similarity). Mediates extraction of PARP1 trapped to chromatin: recognizes and binds ubiquitinated PARP1 and promotes its removal (PubMed:35013556). Required for cytoplasmic retrotranslocation of stressed/damaged mitochondrial outer-membrane proteins and their subsequent proteasomal degradation (PubMed:16186510, PubMed:21118995). Essential for the maturation of ubiquitin-containing autophagosomes and the clearance of ubiquitinated protein by autophagy (PubMed:20104022, PubMed:27753622, PubMed:38762759). Acts as a negative regulator of type I interferon production by interacting with RIGI: interaction takes place when RIGI is ubiquitinated via 'Lys-63'-linked ubiquitin on its CARD domains, leading to recruit RNF125 and promote ubiquitination and degradation of RIGI (PubMed:26471729). May play a role in the ubiquitin-dependent sorting of membrane proteins to lysosomes where they undergo degradation (PubMed:21822278). May more particularly play a role in caveolins sorting in cells (PubMed:21822278, PubMed:23335559). By controlling the steady-state expression of the IGF1R receptor, indirectly regulates the insulin-like growth factor receptor signaling pathway (PubMed:26692333)","subcellular_location":"Cytoplasm, cytosol; Endoplasmic reticulum; Nucleus; Cytoplasm, Stress granule","url":"https://www.uniprot.org/uniprotkb/P55072/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/VCP","classification":"Common Essential","n_dependent_lines":1208,"n_total_lines":1208,"dependency_fraction":1.0},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000165280","cell_line_id":"CID000364","localizations":[{"compartment":"cytoplasmic","grade":3},{"compartment":"nucleoplasm","grade":3},{"compartment":"chromatin","grade":2},{"compartment":"cytoskeleton","grade":1},{"compartment":"er","grade":1}],"interactors":[{"gene":"PTDSS1","stoichiometry":10.0},{"gene":"PSMD2","stoichiometry":4.0},{"gene":"PSMD3","stoichiometry":4.0},{"gene":"CANX","stoichiometry":0.2},{"gene":"DNAJC11","stoichiometry":0.2},{"gene":"HSF1","stoichiometry":0.2},{"gene":"PGRMC1","stoichiometry":0.2},{"gene":"PSMC4","stoichiometry":0.2},{"gene":"PSMD12","stoichiometry":0.2},{"gene":"SAR1B","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000364","total_profiled":1310},"omim":[{"mim_id":"621109","title":"VCP NUCLEAR COFACTOR FAMILY, MEMBER 1; VCF1","url":"https://www.omim.org/entry/621109"},{"mim_id":"620965","title":"SMALL VCP-INTERACTING PROTEIN; SVIP","url":"https://www.omim.org/entry/620965"},{"mim_id":"620608","title":"TESTIS-EXPRESSED GENE 264; TEX264","url":"https://www.omim.org/entry/620608"},{"mim_id":"620529","title":"RING FINGER PROTEIN 121; RNF121","url":"https://www.omim.org/entry/620529"},{"mim_id":"620273","title":"ENDOPLASMIC RETICULUM MEMBRANE PROTEIN COMPLEX, SUBUNIT 3; EMC3","url":"https://www.omim.org/entry/620273"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Cytosol","reliability":"Supported"},{"location":"Mitotic spindle","reliability":"Additional"},{"location":"Primary cilium tip","reliability":"Additional"},{"location":"Primary cilium transition zone","reliability":"Additional"},{"location":"Basal body","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/VCP"},"hgnc":{"alias_symbol":["IBMPFD","p97","CDC48","TERA"],"prev_symbol":[]},"alphafold":{"accession":"P55072","domains":[{"cath_id":"2.40.40.20","chopping":"21-103","consensus_level":"high","plddt":91.2048,"start":21,"end":103},{"cath_id":"3.10.330.10","chopping":"112-182","consensus_level":"high","plddt":89.3854,"start":112,"end":182},{"cath_id":"3.40.50.300","chopping":"202-367","consensus_level":"high","plddt":87.0689,"start":202,"end":367},{"cath_id":"1.10.8.60","chopping":"373-457","consensus_level":"high","plddt":86.2592,"start":373,"end":457},{"cath_id":"3.40.50.300","chopping":"468-587_595-643","consensus_level":"high","plddt":83.2895,"start":468,"end":643},{"cath_id":"1.10.8.60","chopping":"649-712_730-740","consensus_level":"high","plddt":92.4344,"start":649,"end":740}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P55072","model_url":"https://alphafold.ebi.ac.uk/files/AF-P55072-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P55072-F1-predicted_aligned_error_v6.png","plddt_mean":82.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=VCP","jax_strain_url":"https://www.jax.org/strain/search?query=VCP"},"sequence":{"accession":"P55072","fasta_url":"https://rest.uniprot.org/uniprotkb/P55072.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P55072/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P55072"}},"corpus_meta":[{"pmid":"23791177","id":"PMC_23791177","title":"Eukaryotic 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DNA-protein crosslink sites in yeast.","date":"2023","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/37144685","citation_count":14,"is_preprint":false},{"pmid":"33719912","id":"PMC_33719912","title":"VCP/p97 modulates PtdIns3P production and autophagy initiation.","date":"2021","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/33719912","citation_count":14,"is_preprint":false},{"pmid":"35430615","id":"PMC_35430615","title":"The phosphorylation and dephosphorylation switch of VCP/p97 regulates the architecture of centrosome and spindle.","date":"2022","source":"Cell death and differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/35430615","citation_count":14,"is_preprint":false},{"pmid":"20130676","id":"PMC_20130676","title":"A role for Cdc48/p97 and Aurora B in controlling chromatin condensation during exit from mitosis.","date":"2010","source":"Biochemistry and cell biology = Biochimie et biologie 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involved in Cdc13 protein degradation.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22718752","citation_count":13,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":44195,"output_tokens":10048,"usd":0.141652,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":20590,"output_tokens":10137,"usd":0.178187,"stage2_stop_reason":"end_turn"},"total_usd":0.319839,"stage1_batch_id":"msgbatch_01UT1AahFPCAyn2uVweS7A9z","stage2_batch_id":"msgbatch_01HuKWtKNT4Pqj1bc8eEP5RV","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2021,\n      \"finding\": \"The Cdc48/p97 ATPase complex with its cofactor Ufd1/Npl4 (UN) recognizes polyubiquitin chains (rather than the substrate directly), cooperatively binds the chain, unfolds one ubiquitin molecule (initiator), then pulls all ubiquitins linked to its C terminus through the central pore of the hexameric double ring, causing transient ubiquitin unfolding; when the ATPase reaches the isopeptide bond, it translocates and unfolds both N- and C-terminal substrate segments, while ubiquitins linked to the branchpoint dissociate from UN and move outside the pore, releasing unfolded polyubiquitinated substrate.\",\n      \"method\": \"In vitro reconstitution with purified yeast components, hydrogen–deuterium exchange MS, biochemical translocation assays, mutagenesis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstituted in vitro with purified components, multiple orthogonal methods (HDX-MS, translocation assays), mechanistic detail replicated in parallel work\",\n      \"pmids\": [\"34951965\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Bidirectional substrate shuttling between the 26S proteasome and the Cdc48-Ufd1/Npl4 ATPase complex promotes degradation of well-folded substrates. A minimal reconstituted system requires the 26S proteasome, Cdc48-UN complex, proteasome cofactor Rad23, and Cdc48 cofactors Ubx5 and Shp1: Rad23 and Ubx5 stimulate polyubiquitin binding to the proteasome and Cdc48-UN respectively, allowing competition for substrates; Shp1 stimulates protein unfolding by Cdc48-UN rather than substrate recruitment.\",\n      \"method\": \"In vitro reconstitution with purified yeast components, biochemical degradation assays, yeast genetics confirmation\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — full reconstitution with purified components plus in-vivo genetic confirmation, multiple orthogonal assays\",\n      \"pmids\": [\"38401542\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"SUMO modification enhances substrate unfolding by the Ufd1/Npl4/Cdc48 complex: interactions between Ufd1 and SUMO accelerate unfolding of substrates modified by SUMO-polyubiquitin hybrid chains compared to polyubiquitin alone. Cryo-EM structures of the complex with a SUMO-polyubiquitin hybrid-chain substrate reveal features of Ufd1/Npl4/Cdc48 interactions with ubiquitin prior to and during unfolding.\",\n      \"method\": \"In vitro unfolding assays with purified yeast proteins, single-particle cryo-EM structural analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with structural validation by cryo-EM, single lab but two orthogonal methods\",\n      \"pmids\": [\"36574706\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"VCP/p97 is required for autophagosome maturation: loss of VCP activity (by RNAi knockdown or dominant-negative overexpression) results in accumulation of immature autophagosomes under basal conditions; these autophagosomes fail to mature into autolysosomes and degrade LC3. Disease-causing IBMPFD mutants (R155H, A232E) cause the same autophagy defect. VCP is selectively required for autophagic degradation of ubiquitinated substrates but not for starvation-induced autophagy.\",\n      \"method\": \"RNAi knockdown, dominant-negative overexpression, stable dual-tagged LC3 reporter (mCherry-EGFP-LC3), patient-derived myoblasts\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (RNAi, dominant-negative, reporter assay, patient cells), replicated across labs in related papers\",\n      \"pmids\": [\"20008565\", \"20104022\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"VCP/p97 regulates autophagy initiation in two Beclin-1-dependent ways: (1) VCP stabilizes Beclin-1 protein levels by promoting the deubiquitinase activity of ataxin-3 (ATXN3) towards Beclin-1; (2) VCP interacts with and promotes assembly and kinase activity of the Beclin-1-containing PI3K complex I, regulating PI(3)P production. Inhibition of VCP ATPase activity impairs starvation-induced PI(3)P production and limits downstream recruitment of WIPI2, ATG16L, and LC3, decreasing autophagosome formation.\",\n      \"method\": \"Small-molecule VCP ATPase inhibitors, PI(3)P lipid assays, co-immunoprecipitation, deubiquitinase activity assays, WIPI2/ATG16L/LC3 recruitment assays\",\n      \"journal\": \"Nature chemical biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (inhibitors, co-IP, enzymatic assays, recruitment assays) in single rigorous study\",\n      \"pmids\": [\"33510452\", \"33719912\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Cdc48/p97, together with cofactors Ufd1-Npl4, Ubx4, and Ubx5, mediates UV-dependent turnover of RNA Pol II largest subunit Rpb1: ubiquitinated Rpb1, proteasomes, and Cdc48 accumulate on chromatin in UV-treated cells; in cdc48 mutants, Ub conjugates accumulate on the proteasome, indicating Cdc48 acts to facilitate processive degradation at sites of stalled transcription rather than solely upstream of the proteasome.\",\n      \"method\": \"Proteasome isolation followed by mass spectrometry, chromatin fractionation, genetic mutant analysis in yeast\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (MS, fractionation, genetics), mechanistic model supported by epistasis data\",\n      \"pmids\": [\"21211725\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"IBMPFD disease-causing VCP/p97 mutant R155H has normal ATPase activity and hexameric structure, yet impairs ERAD: it increases overall ubiquitin-conjugated proteins and specifically blocks degradation of the ERAD substrate ΔF508-CFTR, similar to ATPase-deficient VCP. IBMPFD mutants also promote formation of aggregates containing VCP, ubiquitin conjugates, and ER-resident proteins.\",\n      \"method\": \"Cell-based ERAD substrate degradation assays, ATPase activity measurement, native gel electrophoresis, immunofluorescence/co-localization in cultured cells\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (biochemical, cell-based substrate assays, structural analysis), single lab\",\n      \"pmids\": [\"16321991\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Cdc48/p97-Ufd1-Npl4 complex removes Aurora B from chromatin during mitotic exit in Xenopus egg extracts; in HeLa cells, Ufd1-Npl4 antagonizes Aurora B on chromosomes from prometaphase onwards. Depletion of Ufd1-Npl4 by siRNA causes increased Aurora B levels and activity on chromosomes, chromosome alignment and anaphase defects, and multi-lobed nuclei; low-dose Aurora B inhibitor partially rescues these defects.\",\n      \"method\": \"siRNA depletion, quantitative immunofluorescence, Aurora B kinase activity assay (CENP-A phosphorylation), genetic epistasis with hesperadin inhibitor in HeLa cells\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal genetic epistasis plus kinase activity readout, replicated across Xenopus and human cell systems\",\n      \"pmids\": [\"21486945\", \"20130676\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"In budding yeast, Cdc48-Shp1 complex promotes chromosome bi-orientation by facilitating nuclear localization of the phosphatase Glc7/PP1, which counteracts Ipl1/Aurora B kinase activity at kinetochores. Temperature-sensitive cdc48-3 and Shp1 depletion cause metaphase arrest due to defective bipolar kinetochore attachment and spindle checkpoint activation.\",\n      \"method\": \"Yeast temperature-sensitive mutants, co-immunoprecipitation, nuclear localization imaging, genetic epistasis with ipl1 mutants and kinase inhibitors\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with biochemical validation, mechanistic pathway clearly defined\",\n      \"pmids\": [\"20483956\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Cdc48/VCP promotes chromosome condensation by releasing condensin from chromatin entrapment via ubiquitin-dependent extraction. Condensin traps itself in its own reaction product during chromatin compaction; Cdc48 acts as the central segregase that promotes ubiquitin-dependent cycling of condensin on mitotic chromatin.\",\n      \"method\": \"Yeast genetics, in vivo chromatin binding assays, ubiquitin mutant epistasis, condensin-chromatin dynamics assays\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo epistasis and chromatin binding assays, single lab, multiple genetic methods\",\n      \"pmids\": [\"29452641\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"In yeast, stress granules can be targeted for autophagic degradation (granulophagy) in a process requiring CDC48/VCP. Genetic screen identified CDC48 alleles as affecting stress granule dynamics; in mammalian cells, depletion or pathogenic mutations in VCP reduce stress granule clearance, an effect also seen with autophagy inhibition.\",\n      \"method\": \"Yeast genetic screen (125 genes), fluorescence microscopy of stress granule dynamics, RNAi depletion, patient mutation expression in mammalian cells\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — unbiased genetic screen plus mechanistic validation in both yeast and mammalian cells with multiple methods\",\n      \"pmids\": [\"23791177\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"ULK1 and ULK2 kinases phosphorylate VCP/p97, thereby increasing VCP's ATPase activity and its ability to disassemble stress granules. ULK1/2 localize to stress granules; disrupted ULK1/2 expression in mice causes a vacuolar myopathy similar to VCP disease with TDP-43-positive inclusions.\",\n      \"method\": \"Kinase phosphorylation assays, stress granule disassembly assays, VCP ATPase activity measurement, mouse knockout models, ULK1/2 agonist pharmacology\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vitro kinase assay plus ATPase activity measurement plus in vivo mouse model, multiple orthogonal methods\",\n      \"pmids\": [\"30979586\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"A p.Asp395Gly mutation in VCP is associated with dementia characterized by neurofibrillary tangles. Wild-type VCP exhibits tau disaggregase activity in vitro, which is impaired by the p.Asp395Gly mutation. Intracerebral microinjection of pathologic tau into p.Asp395Gly VCP knock-in mice leads to increased tau aggregates compared to wild-type mice.\",\n      \"method\": \"In vitro tau disaggregation assay with purified VCP, VCP knock-in mouse model with intracerebral tau microinjection, neuropathological analysis\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro disaggregation assay with purified protein plus in vivo knock-in mouse model, two orthogonal methods\",\n      \"pmids\": [\"33004675\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In cell culture and neurons, VCP is recruited to ubiquitylated Tau fibrils and efficiently disaggregates them; aggregate clearance depends on functional cooperation of VCP with Hsp70 and the ubiquitin-proteasome machinery. Inhibition of VCP stabilizes large Tau aggregates, whereas VCP-mediated disaggregation generates seeding-active Tau species as a byproduct.\",\n      \"method\": \"Cell culture Tau aggregate clearance assays, VCP inhibitors, VCP depletion, live-cell imaging, seeding activity assays in neurons\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (inhibitors, depletion, live imaging, seeding assays), replicated in cells and neurons\",\n      \"pmids\": [\"36732333\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Endogenous VCP negatively regulates Mitofusin, which is required for outer mitochondrial membrane fusion. IBMPFD disease mutants of VCP act as hyperactive alleles with respect to Mitofusin regulation; VCP inhibitors suppress mitochondrial fusion and respiratory defects in IBMPFD patient fibroblasts and in a Drosophila IBMPFD muscle model.\",\n      \"method\": \"Drosophila in vivo IBMPFD muscle model, patient fibroblast assays, VCP inhibitor treatment, mitochondrial morphology/respiration assays\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo model plus patient cell validation, two orthogonal systems, single lab\",\n      \"pmids\": [\"28322724\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"VCP, together with cofactor P47 and the ER morphology regulator ATL1, regulates tubular ER formation and controls protein synthesis efficiency to influence dendritic spine formation in neurons. Knockdown or disease mutation knockin of VCP reduces dendritic spine density; leucine supplementation (increasing protein synthesis) rescues spine defects caused by VCP deficiency.\",\n      \"method\": \"Knockdown, disease-mutation knockin mice, live imaging of ER morphology, protein synthesis measurement, dendritic spine morphometry in neurons\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple genetic approaches plus functional readouts in neurons, single lab\",\n      \"pmids\": [\"26984393\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"VCP/p97 is highly modified by phosphorylation and acetylation at numerous sites throughout the protein. Amino acid substitutions at Lys696 and Thr761 (in the D2alpha/VAR domain) profoundly affect VCP ATPase activity, identifying this region as an ATPase regulatory domain. Lys251 and Lys524 (Walker A motifs of D1 and D2 domains) are potential acetylation sites.\",\n      \"method\": \"Mass spectrometry identification of modification sites, site-directed mutagenesis with ATPase activity measurement\",\n      \"journal\": \"Genes to cells : devoted to molecular & cellular mechanisms\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — mutagenesis with enzymatic assay, single lab, limited follow-up on regulatory consequences\",\n      \"pmids\": [\"19335618\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The UBX domain protein Ubx4 modulates the Cdc48-Ufd1-Npl4 complex for correct ERAD function. Ubx4 mutants defective in Cdc48 binding lead to defective degradation of ERAD substrates and accumulation of polyubiquitinated proteins bound to Cdc48. Ubx2 and Ubx4 are not found together in one Cdc48 complex, suggesting distinct steps in modulating Cdc48 activity in ERAD.\",\n      \"method\": \"Yeast genetics with ERAD substrate degradation assays, co-immunoprecipitation, polyubiquitin accumulation assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple genetic and biochemical approaches, single lab, clear substrate phenotype\",\n      \"pmids\": [\"19359248\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"In budding yeast, defective RNA polymerase III (Pol III) is negatively regulated by a sequential SUMO–ubiquitin–Cdc48 pathway: Pol III is sumoylated, then ubiquitylated, and subsequently targeted by Cdc48/p97 segregase, leading to proteasomal degradation of Pol III subunits and repression of Pol III transcription.\",\n      \"method\": \"Yeast genetics, sumoylation and ubiquitylation assays, Cdc48 mutant analysis, proteasomal degradation assays\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic and biochemical epistasis, single lab, multiple modifications characterized\",\n      \"pmids\": [\"30192228\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"WIPI2 binds VCP/p97 and promotes its recruitment to damaged mitochondria during PINK1-PRKN-mediated mitophagy. WIPI2 depletion blunts VCP recruitment to damaged mitochondria, leading to reduced degradation of outer mitochondrial membrane proteins and impaired mitophagy.\",\n      \"method\": \"Co-immunoprecipitation, RNAi depletion, mitophagy flux assays, OMM protein degradation assays, cell death assays\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP plus functional depletion assays with defined substrate readout, single lab\",\n      \"pmids\": [\"35389758\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"VCP cofactor UBXN1/SAKS1 translocates to mitochondria upon depolarization in a PRKN-dependent manner and facilitates MFN2 removal from the outer mitochondrial membrane; loss of UBXN1 impairs VCP and PRKN translocation to mitochondria and reduces mitophagic flux. UBXN1 physically interacts with PRKN in a UBX domain-dependent manner.\",\n      \"method\": \"Co-immunoprecipitation, siRNA depletion, mitophagy flux assays, immunofluorescence imaging of mitochondrial translocation, domain mapping\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP with domain mapping plus functional depletion assays, single lab\",\n      \"pmids\": [\"33966597\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Polo-like kinase 1 (Plk1) phosphorylates VCP/p97 at Thr76, recruiting VCP to the centrosome from prophase to anaphase and regulating centrosome orientation. Dephosphorylation of Thr76 by PTEN is required for VCP and Eg5 enrichment at the mitotic spindle, ensuring proper spindle architecture and chromosome segregation. Cryo-EM structures of phosphomimetic (T76E) and phospho-deficient (T76A) VCP revealed that Thr76 phosphorylation alters inter-domain/inter-subunit interactions and the nucleotide-binding pocket conformation.\",\n      \"method\": \"Kinase assay, phospho-mutant cell biology, siRNA depletion, cryo-EM structural analysis, co-localization imaging, xenograft tumor growth assay\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay with structural cryo-EM validation and multiple cell-biology readouts, single lab with orthogonal methods\",\n      \"pmids\": [\"35430615\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"VCP/p97 is UFMylated at K109 by the E3 ligase UFL1; this modification promotes BECN1 stabilization through ATXN3-mediated deubiquitination and facilitates assembly of the BECN1-containing PI3K complex, thereby promoting autophagy initiation. UFMylation-defective VCP mutant cannot rescue VCP depletion-induced LC3B accumulation. Several pathogenic VCP mutations are associated with reduced UFMylation.\",\n      \"method\": \"Mass spectrometry identification of UFMylation site, site-directed mutagenesis, co-immunoprecipitation, BECN1 stability assays, LC3B reporter assays\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — MS site identification plus mutagenesis plus functional rescue assays, single lab\",\n      \"pmids\": [\"38762759\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"DUSP1 phosphatase interacts with VCP on mitochondria and dephosphorylates VCP at Ser784. LPS-induced endotoxemia promotes VCP Ser784 phosphorylation; DUSP1 overexpression prevents this, preserving mitochondrial quality control. A phosphomimetic VCP S784E mutant abolishes DUSP1's protective effects on mitochondrial dynamics, mitophagy, and cardiomyocyte contractility.\",\n      \"method\": \"Co-immunoprecipitation, phospho-specific antibodies, site-directed mutagenesis (phosphomimetic), DUSP1 transgenic mice and HL-1 cell transfection, mitochondrial function assays\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus mutagenesis plus in vivo transgenic model, single lab, multiple readouts\",\n      \"pmids\": [\"37464072\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PTP4A2 phosphatase dephosphorylates VCP/p97 at Tyr805; this dephosphorylation enables VCP to associate with its C-terminal cofactors UBXN6/UBXD1 and PLAA, which are components of the ELDR complex responsible for lysophagy (autophagic clearance of damaged lysosomes). Loss of PTP4A2 compromises recovery from acute kidney injury due to impaired lysophagy.\",\n      \"method\": \"Substrate trapping and mass spectrometry, biochemical dephosphorylation assays, co-immunoprecipitation, lysophagy assays, Ptp4a2 knockout mice\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — unbiased substrate trapping + MS identification + biochemical validation + in vivo knockout model, multiple orthogonal methods, single lab\",\n      \"pmids\": [\"36300783\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"VCP's cofactor FAF1 facilitates VCP-dependent extraction of SUMOylated and ubiquitylated proteins accumulating on chromatin after DNA replication blocks; this VCP(FAF1) activity cooperates with the deubiquitylase USP7 (which maintains a SUMO-high/ubiquitin-low environment at active replication forks). Inactivation of USP7 and FAF1 is synthetically lethal in C. elegans and mammalian cells.\",\n      \"method\": \"Co-immunoprecipitation, chromatin fractionation, C. elegans and mammalian cell genetics, synthetic lethality assays, VCP and USP7 inhibitor synergy\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis plus biochemical chromatin fractionation, replicated from worm to mammalian cells, single main lab\",\n      \"pmids\": [\"34644576\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"The p97/VCP UFD1-NPLOC4 segregase complex is required for arsenic-induced degradation of PML and PML-RARA. p97/VCP localizes to PML bodies after arsenic treatment; pharmacological p97 inhibition or siRNA depletion of UFD1/NPLOC4 blocks arsenic-induced degradation of PML-RARA, accumulates SUMO- and ubiquitin-modified PML, and alters PML body number, morphology, and size.\",\n      \"method\": \"Proteomic analysis of PML bodies, pharmacological p97 inhibition, siRNA depletion, immunofluorescence, biochemical PML modification analysis\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (proteomics, inhibitors, siRNA, imaging), single lab\",\n      \"pmids\": [\"36880596\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Inhibited WRN helicase is trapped on chromatin and requires p97/VCP for extraction and proteasomal degradation in microsatellite-instability-high (MSI-H) cancer cells. The PIAS4-RNF4 SUMO-ubiquitin axis is responsible for generating the SUMOylated/ubiquitylated WRN signal recognized by p97/VCP for chromatin extraction.\",\n      \"method\": \"Single-molecule tracking in living cells, pharmacological WRN inhibition, p97 inhibition, PIAS4 and RNF4 genetic epistasis, chromatin fractionation\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — single-molecule tracking plus genetic epistasis plus biochemical fractionation, single lab, novel method combination\",\n      \"pmids\": [\"39025847\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Ubx5-Cdc48 assists the protease Wss1 in clearing DNA-protein crosslinks (DPCs): Ubx5 accumulates at persistent DPC lesions in the absence of Wss1; abolishing Cdc48 binding by Ubx5 or complete Ubx5 loss suppresses wss1Δ sensitivity to DPC-inducing agents by favoring alternate repair pathways. Ubx5-Cdc48 and Wss1 cooperate in genotoxin-induced degradation of RNA Pol II at DPC lesions.\",\n      \"method\": \"Yeast genetics, inducible site-specific crosslink assay, chromatin immunoprecipitation, genetic epistasis, RNAPII degradation assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple genetic and biochemical approaches with inducible model system, single lab\",\n      \"pmids\": [\"37144685\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1993,\n      \"finding\": \"VCP forms a stoichiometric complex with clathrin and Hsc70 in mammalian cell lysates within 15 min of synthesis, identifying VCP as a ubiquitous clathrin-binding protein and suggesting a role in modulating protein-protein interactions in membrane transport processes.\",\n      \"method\": \"Biochemical co-purification, co-immunoprecipitation, stoichiometric complex analysis from mammalian cell lysates\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-purification/co-IP establishing complex formation, no functional mechanism assayed, replicated in multiple cell types\",\n      \"pmids\": [\"8413590\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Both Cdc48 and its cofactor Vms1 (but not Ufd1 or Ufd2) are required for degradation of the telomere regulator Cdc13; this degradation involves both autophagy and the proteasome under non-stress conditions.\",\n      \"method\": \"Yeast deletion mutant analysis, Cdc13 stability assays, autophagy and proteasome inhibition genetics\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with defined substrate, single lab, multiple pathway interrogation\",\n      \"pmids\": [\"22718752\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"In IBMPFD, all twelve pathogenic p97/VCP missense mutants cause ERAD substrate accumulation. Most IBMPFD mutants show enhanced binding to cofactors p47 and Ufd1-Npl4. However, the P137L mutant uniquely abolishes interactions with Ufd1, Npl4, and p47 while retaining gp78-VIM binding, and shows a distinct solubility profile and subcellular localization compared to other IBMPFD mutants.\",\n      \"method\": \"ERAD substrate degradation assays, in vitro protein-protein binding assays with recombinant proteins, co-immunoprecipitation, subcellular fractionation, immunofluorescence\",\n      \"journal\": \"The international journal of biochemistry & cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple methods (in vitro binding, co-IP, cell assays, fractionation), single lab, comprehensive mutant panel\",\n      \"pmids\": [\"23333620\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"An ALS-disease-associated aspartate mutation in the pore-2 loop of the D2 ring of Cdc48/p97 impairs 20S proteasome binding and proteolytic communication but does not affect hexamer stability, ATP hydrolysis rate, or protein unfolding activity, identifying the pore-2 loop as a critical element for direct Cdc48–20S proteasome interaction.\",\n      \"method\": \"In vitro binding assays between purified archaeal/human Cdc48 variants and 20S proteasome, ATPase activity measurement, protein unfolding assays, hexamer stability analysis, site-directed mutagenesis\",\n      \"journal\": \"Protein science : a publication of the Protein Society\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro biochemical reconstitution with mutagenesis, single lab, multiple functional readouts\",\n      \"pmids\": [\"26134898\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Archaeal Cdc48 and 20S proteasome form a stable, enzymatically active coaxial complex stabilized by site-specific cross-linking. The N-terminal domain of Cdc48 packs against the D1 ring in a coplanar fashion in this complex, and the structure demonstrates that coaxial alignment without AAA+ wobbling is sufficient for function.\",\n      \"method\": \"Site-specific chemical cross-linking, single-particle electron microscopy structure determination, in vitro proteolytic activity assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — EM structure with biochemical reconstitution and activity validation, single study\",\n      \"pmids\": [\"24711419\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"VCP inactivation in skeletal muscle of adult mice (conditional knockout) causes lysosomal membrane damage, persistent TFEB nuclear localization, and a necrotic myopathy distinct from ATG5 knockout, identifying VCP as a central mediator of both lysosomal clearance and TFEB-regulated lysosomal biogenesis in differentiated muscle.\",\n      \"method\": \"Conditional muscle-specific knockout mice, lysosomal damage markers (LGALS3), TFEB localization by immunofluorescence, comparison with ATG5 knockout mice, chemical lysosomal membrane permeabilization\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional knockout mouse model plus multiple cellular readouts, comparison with another autophagy gene knockout as control, single lab\",\n      \"pmids\": [\"30654731\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Nuclear VCP binds to HDAC1 and facilitates its degradation, thereby promoting transcription of FAO genes including CPT1A, upregulating fatty acid oxidation in colorectal cancer cells.\",\n      \"method\": \"Co-immunoprecipitation, VCP inhibitor and knockdown experiments, chromatin-based transcription assays, HDAC1 stability assays, cancer cell functional assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus functional knockdown/inhibitor assays with transcriptional readout, single lab\",\n      \"pmids\": [\"37788309\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"VCP is a top hit in a proximity-labeling screen for proteins that control tau seed amplification within 5 h of seed exposure. VCP knockdown reduces tau seeding; two VCP inhibitors (ML-240 and NMS-873) have opposing effects on seeding, with effects only observed within 8 h of seed exposure. Screening 30 VCP cofactors identified ATXN3, NSFL1C, UBE4B, NGLY1, OTUB1, and NPLOC4 as suppressors of tau seeding, while FAF2 reduction increases seeding.\",\n      \"method\": \"Split-APEX2 proximity labeling screen, CRISPR/siRNA cofactor screen, tau seeding biosensor assays in HEK293T cells and human neurons, VCP inhibitor pharmacology\",\n      \"journal\": \"Molecular neurodegeneration\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — unbiased proximity screen plus cofactor epistasis screen plus pharmacology, single lab, multiple complementary methods\",\n      \"pmids\": [\"39773263\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Neuronal VCP loss of function (conditional knockout in postnatal forebrain neurons) causes cortical atrophy, neuronal loss, autophagolysosomal dysfunction, and TDP-43 inclusions resembling FTLD-TDP pathology. A single disease-associated VCP-R155C mutation in a VCP null background similarly recapitulates VCP inactivation features, suggesting the R155C MSP mutation is hypomorphic (loss-of-function rather than dominant-negative).\",\n      \"method\": \"Conditional neuronal knockout mice, VCP-R155C knock-in in null background, transcriptomic and proteomic analysis, TDP-43 immunohistochemistry\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional knockout mouse model with genetic epistasis (rescue by single mutant allele), single lab\",\n      \"pmids\": [\"34289347\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"VCP/p97 (CDC48) is a hexameric AAA+ ATPase that uses ATP hydrolysis—primarily in the D2 domain—to thread polyubiquitinated client proteins through its central pore, unfolding substrates and extracting them from membranes, protein complexes, and chromatin; it acts together with a large network of cofactors (principally Ufd1-Npl4 for ubiquitin-modified substrates, and SEP-domain adaptors for ubiquitin-independent targeting) to deliver clients to the proteasome or autophagy pathway, and it additionally regulates autophagy initiation via Beclin-1 stabilization (through ATXN3 deubiquitinase activity) and PI3K complex assembly, stress granule disassembly (activated by ULK1/2-mediated phosphorylation), chromosome segregation (by removing Aurora B from chromatin), ERAD retrotranslocation, tau/aggregate disaggregation, and mitochondrial quality control, with its activity further tuned by post-translational modifications including phosphorylation (Thr76 by Plk1/PTEN; Ser784 by DUSP1; Tyr805 by PTP4A2), acetylation, and UFMylation (K109 by UFL1).\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"VCP/p97 (yeast Cdc48) is a hexameric AAA+ ATPase segregase that uses ATP hydrolysis to extract and unfold ubiquitinated client proteins from membranes, chromatin, and protein complexes, delivering them to the proteasome or autophagy machinery [#0, #1]. With its core cofactor Ufd1-Npl4, VCP cooperatively engages polyubiquitin chains rather than the substrate directly, unfolds an initiator ubiquitin, and threads the linked chain and substrate segments through its central pore [#0]; SUMO-polyubiquitin hybrid chains accelerate this unfolding through Ufd1-SUMO contacts [#2]. Substrate handoff to the 26S proteasome is bidirectional and depends on adaptor cofactors (Rad23, Ubx5/Shp1) that partition polyubiquitin binding and stimulate unfolding [#1], and direct Cdc48-20S coaxial coupling occurs through the D2-ring pore-2 loop [#32, #33]. VCP performs ubiquitin-dependent chromatin extraction across diverse contexts: removing Aurora B during mitotic exit [#7], cycling condensin during chromosome condensation [#9], degrading stalled/damaged RNA polymerases [#5, #18], and extracting SUMO-ubiquitin-marked factors at replication forks and DNA-protein crosslinks (FAF1, Ubx5/Wss1) [#25, #28]. VCP is also central to protein quality control: it drives ERAD retrotranslocation [#6, #17], stress-granule disassembly upon ULK1/2 phosphorylation [#10, #11], lysosomal clearance and TFEB-regulated lysosomal biogenesis [#34], mitochondrial quality control via Mitofusin/MFN2 removal and PINK1-PRKN mitophagy [#14, #19, #20], and Hsp70-assisted disaggregation of ubiquitylated tau fibrils [#12, #13]. VCP additionally regulates autophagy initiation by stabilizing Beclin-1 through ATXN3 deubiquitinase activity and promoting PI3K complex I assembly [#4]. Its activity is tuned by post-translational modifications including UFMylation at K109 by UFL1 [#22], phosphorylation at Thr76 (Plk1/PTEN), Ser784 (DUSP1), and Tyr805 (PTP4A2, gating UBXD1/PLAA-dependent lysophagy) [#21, #23, #24], and acetylation [#16]. Disease-causing IBMPFD/MSP and dementia mutations (R155H, A232E, R155C, D395G) impair ERAD, autophagosome maturation, and tau disaggregation, establishing VCP as causal in multisystem proteinopathy and tauopathy [#3, #6, #12, #37].\",\n  \"teleology\": [\n    {\n      \"year\": 1993,\n      \"claim\": \"Established VCP's first physical association in membrane traffic, showing it stoichiometrically binds clathrin and Hsc70 and might modulate protein-protein interactions in transport.\",\n      \"evidence\": \"Biochemical co-purification and co-immunoprecipitation from mammalian cell lysates\",\n      \"pmids\": [\"8413590\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional mechanism assayed\", \"Role of ATPase activity in clathrin/Hsc70 complex not tested\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Linked IBMPFD disease mutations to a loss of ERAD function, showing R155H impairs degradation of an ERAD substrate despite normal ATPase activity and hexamer structure.\",\n      \"evidence\": \"Cell-based ERAD substrate degradation assays, ATPase measurement, native gel, immunofluorescence\",\n      \"pmids\": [\"16321991\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of substrate-handling defect with intact ATPase unresolved\", \"Did not establish whether mutation is gain or loss of function\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Defined VCP as required for autophagosome maturation, distinguishing ubiquitin-dependent autophagy of substrates from starvation-induced autophagy and tying disease mutants to the defect.\",\n      \"evidence\": \"RNAi, dominant-negative overexpression, mCherry-EGFP-LC3 reporter, patient myoblasts\",\n      \"pmids\": [\"20008565\", \"20104022\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve which maturation step VCP acts on\", \"Cofactor requirements not defined\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Mapped VCP as heavily phosphorylated/acetylated and identified a D2alpha/VAR regulatory region controlling ATPase activity.\",\n      \"evidence\": \"Mass spectrometry of modification sites plus site-directed mutagenesis with ATPase assays\",\n      \"pmids\": [\"19335618\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological enzymes and consequences of most modifications not established\", \"Limited follow-up on regulatory outcomes\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Extended VCP function to chromatin, showing it acts at sites of stalled transcription to facilitate processive proteasomal degradation of ubiquitinated Rpb1 after UV.\",\n      \"evidence\": \"Proteasome isolation/MS, chromatin fractionation, yeast genetics\",\n      \"pmids\": [\"21211725\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Precise extraction step at chromatin not visualized\", \"Generalization beyond Pol II unclear at the time\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Connected VCP to chromosome bi-orientation via Cdc48-Shp1-driven nuclear localization of PP1, counteracting Aurora B at kinetochores.\",\n      \"evidence\": \"Yeast ts mutants, co-IP, localization imaging, genetic epistasis with ipl1\",\n      \"pmids\": [\"20483956\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct substrate of Cdc48 in this pathway not identified\", \"Conservation to human kinetochores not tested here\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Demonstrated direct Cdc48-Ufd1-Npl4 removal of Aurora B from chromatin during mitotic exit across Xenopus and human systems, defining a mitotic role for the segregase.\",\n      \"evidence\": \"siRNA, quantitative IF, Aurora B kinase activity assay, epistasis with hesperadin\",\n      \"pmids\": [\"21486945\", \"20130676\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Aurora B is a direct VCP substrate not shown biochemically\", \"Ubiquitin ligase upstream unidentified\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Showed the UBX cofactor Ubx4 modulates Cdc48-Ufd1-Npl4 for ERAD, defining distinct cofactor-dependent steps in substrate handling.\",\n      \"evidence\": \"Yeast genetics, ERAD substrate assays, co-IP, polyubiquitin accumulation\",\n      \"pmids\": [\"19359248\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic step controlled by Ubx4 vs Ubx2 not fully defined\", \"Mammalian relevance untested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified a Vms1-dependent, Ufd1/Ufd2-independent Cdc48 route degrading the telomere regulator Cdc13 via both autophagy and proteasome.\",\n      \"evidence\": \"Yeast deletion mutants, Cdc13 stability assays, pathway inhibition genetics\",\n      \"pmids\": [\"22718752\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct extraction mechanism not shown\", \"Choice between autophagy and proteasome unexplained\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Established granulophagy, a CDC48/VCP-dependent autophagic clearance of stress granules conserved from yeast to mammals and sensitive to disease mutations.\",\n      \"evidence\": \"Unbiased yeast genetic screen, fluorescence microscopy, RNAi, patient mutation expression\",\n      \"pmids\": [\"23791177\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Substrate within stress granules targeted by VCP unidentified\", \"Trigger for VCP recruitment unclear\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Characterized a comprehensive IBMPFD mutant panel, showing all cause ERAD substrate accumulation and most enhance Ufd1-Npl4/p47 binding, with P137L as a distinct cofactor-binding-deficient outlier.\",\n      \"evidence\": \"ERAD assays, in vitro binding, co-IP, fractionation, IF\",\n      \"pmids\": [\"23333620\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How enhanced cofactor binding causes dysfunction not resolved\", \"Functional uniqueness of P137L mechanistically unexplained\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Provided structural proof that Cdc48 and the 20S proteasome form a stable coaxial complex, showing coplanar N-D1 packing is sufficient for function.\",\n      \"evidence\": \"Site-specific cross-linking, single-particle EM, in vitro proteolysis (archaeal)\",\n      \"pmids\": [\"24711419\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relevance of archaeal coupling to eukaryotic 26S not established\", \"Substrate handoff geometry not resolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Pinpointed the D2-ring pore-2 loop as the element mediating Cdc48-20S interaction, separating proteasome communication from unfolding/ATPase activity, and linked an ALS mutation to this surface.\",\n      \"evidence\": \"In vitro binding of purified Cdc48 variants and 20S, ATPase, unfolding, hexamer stability assays\",\n      \"pmids\": [\"26134898\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In-cell consequence of impaired 20S coupling not measured\", \"Disease mechanism in neurons not tested\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Revealed a neuronal role for VCP-p47-ATL1 in tubular ER formation and protein synthesis controlling dendritic spine density, with rescue by leucine.\",\n      \"evidence\": \"Knockdown, disease-mutation knockin mice, ER live imaging, protein synthesis and spine morphometry\",\n      \"pmids\": [\"26984393\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct VCP substrate linking ER shape to translation unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identified Mitofusin as a target negatively regulated by VCP, with IBMPFD mutants as hyperactive alleles suppressible by VCP inhibitors in patient and fly models.\",\n      \"evidence\": \"Drosophila IBMPFD muscle model, patient fibroblasts, VCP inhibitors, mitochondrial morphology/respiration\",\n      \"pmids\": [\"28322724\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct extraction of Mitofusin not biochemically reconstituted\", \"Cofactor dependence unclear\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined a sequential SUMO-ubiquitin-Cdc48 pathway degrading defective RNA Pol III, broadening VCP's transcriptional quality-control role.\",\n      \"evidence\": \"Yeast genetics, sumoylation/ubiquitylation assays, Cdc48 mutant and degradation analysis\",\n      \"pmids\": [\"30192228\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Ligases and recognition determinants partially defined\", \"Mammalian conservation untested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed Cdc48 acts as the segregase releasing self-entrapped condensin from chromatin to enable chromosome condensation.\",\n      \"evidence\": \"Yeast genetics, chromatin binding assays, ubiquitin mutant epistasis\",\n      \"pmids\": [\"29452641\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct condensin ubiquitination/extraction not biochemically reconstituted\", \"Single lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstrated ULK1/2 phosphorylate VCP to boost its ATPase activity and stress-granule disassembly, linking the kinases to VCP-disease-like myopathy with TDP-43 inclusions.\",\n      \"evidence\": \"Kinase assays, SG disassembly assays, VCP ATPase measurement, mouse knockouts, ULK agonists\",\n      \"pmids\": [\"30979586\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphosite(s) and structural mechanism of activation not mapped here\", \"Substrate extracted from SGs unidentified\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Established VCP as a central mediator of lysosomal clearance and TFEB-regulated lysosomal biogenesis in adult muscle, causing a necrotic myopathy distinct from ATG5 loss.\",\n      \"evidence\": \"Conditional muscle knockout mice, lysosomal damage markers, TFEB localization, ATG5-KO comparison\",\n      \"pmids\": [\"30654731\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular substrate at damaged lysosomes not defined here\", \"Link to TFEB regulation mechanistically open\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identified VCP as a tau disaggregase whose activity is impaired by a dementia-associated D395G mutation, directly linking VCP to neurofibrillary tangle pathology.\",\n      \"evidence\": \"In vitro tau disaggregation with purified VCP, D395G knock-in mice with intracerebral tau injection\",\n      \"pmids\": [\"33004675\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cofactor requirements for in vivo disaggregation not defined here\", \"Fate of disaggregated tau unresolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Resolved the core unfolding mechanism: Cdc48-Ufd1/Npl4 recognizes the polyubiquitin chain, unfolds an initiator ubiquitin, and threads chain plus substrate through the pore to release unfolded client.\",\n      \"evidence\": \"In vitro reconstitution with purified yeast components, HDX-MS, translocation assays, mutagenesis\",\n      \"pmids\": [\"34951965\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cofactor-specific modulation of this cycle not fully mapped\", \"Membrane-embedded substrate extraction not addressed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defined a dual mechanism for VCP in autophagy initiation: stabilizing Beclin-1 via ATXN3 deubiquitination and promoting PI3K complex I assembly and PI(3)P production.\",\n      \"evidence\": \"VCP ATPase inhibitors, PI(3)P assays, co-IP, DUB activity, WIPI2/ATG16L/LC3 recruitment\",\n      \"pmids\": [\"33510452\", \"33719912\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether VCP directly extracts a ubiquitin from Beclin-1 unresolved\", \"Structural basis of PI3K-complex assembly role unknown\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defined VCP(FAF1) chromatin extraction of SUMO/ubiquitin-modified proteins at blocked replication forks, cooperating with USP7 in a synthetic-lethal relationship.\",\n      \"evidence\": \"Co-IP, chromatin fractionation, C. elegans and mammalian genetics, synthetic lethality, inhibitor synergy\",\n      \"pmids\": [\"34644576\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Identity of extracted fork-associated substrates partial\", \"Single main lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Established UBXN1/SAKS1 as the cofactor coupling VCP to PRKN-dependent mitophagy, facilitating MFN2 removal from the OMM.\",\n      \"evidence\": \"Co-IP, siRNA, mitophagy flux, IF translocation, domain mapping\",\n      \"pmids\": [\"33966597\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct extraction of MFN2 by VCP not reconstituted\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Showed neuronal VCP loss recapitulates FTLD-TDP pathology and that disease mutant R155C behaves as a hypomorphic loss-of-function allele.\",\n      \"evidence\": \"Conditional neuronal knockout mice, R155C knock-in in null background, omics, TDP-43 IHC\",\n      \"pmids\": [\"34289347\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether all MSP mutations are loss-of-function not generalized\", \"Molecular driver of TDP-43 inclusions unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Showed SUMO modification of substrates accelerates VCP-mediated unfolding via Ufd1-SUMO contacts, with cryo-EM capturing the hybrid-chain engaged complex.\",\n      \"evidence\": \"In vitro unfolding with purified yeast proteins, single-particle cryo-EM\",\n      \"pmids\": [\"36574706\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Generality of SUMO acceleration across substrates unclear\", \"Physiological SUMO-Ub hybrid substrates in cells not enumerated\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined Plk1 phosphorylation of VCP at Thr76 (reversed by PTEN) as a switch positioning VCP at the centrosome versus spindle, with cryo-EM showing nucleotide-pocket conformational changes.\",\n      \"evidence\": \"Kinase assay, phospho-mutant cell biology, siRNA, cryo-EM, co-localization, xenograft\",\n      \"pmids\": [\"35430615\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Substrates extracted at centrosome/spindle not identified\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Established WIPI2 as the factor recruiting VCP to damaged mitochondria during PINK1-PRKN mitophagy for OMM protein degradation.\",\n      \"evidence\": \"Co-IP, RNAi, mitophagy flux, OMM degradation, cell death assays\",\n      \"pmids\": [\"35389758\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of WIPI2-VCP coupling structurally undefined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Showed PTP4A2 dephosphorylation of VCP at Tyr805 enables binding of C-terminal cofactors UBXD1/PLAA (ELDR complex) for lysophagy, with in vivo relevance to kidney injury recovery.\",\n      \"evidence\": \"Substrate trapping/MS, dephosphorylation assays, co-IP, lysophagy assays, Ptp4a2-KO mice\",\n      \"pmids\": [\"36300783\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase that phosphorylates Tyr805 unidentified\", \"Direct lysophagy substrate of VCP not defined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Showed VCP disaggregates ubiquitylated tau fibrils in neurons in cooperation with Hsp70 and the ubiquitin-proteasome system, but generates seeding-active byproducts.\",\n      \"evidence\": \"Cell/neuron clearance assays, VCP inhibitors, depletion, live imaging, seeding assays\",\n      \"pmids\": [\"36732333\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Determinants partitioning clearance versus seed generation unclear\", \"In vivo relevance of seeding byproducts untested\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified DUSP1-mediated dephosphorylation of VCP at Ser784 as preserving mitochondrial quality control during endotoxemia in cardiomyocytes.\",\n      \"evidence\": \"Co-IP, phospho-antibodies, phosphomimetic mutagenesis, DUSP1 transgenic mice, HL-1 cells, mitochondrial assays\",\n      \"pmids\": [\"37464072\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Kinase phosphorylating Ser784 not identified\", \"Structural effect of Ser784 modification unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Showed nuclear VCP degrades HDAC1 to drive transcription of fatty-acid-oxidation genes (CPT1A) in colorectal cancer, defining a transcriptional/metabolic role.\",\n      \"evidence\": \"Co-IP, VCP inhibitor/knockdown, transcription assays, HDAC1 stability, cancer functional assays\",\n      \"pmids\": [\"37788309\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Ubiquitin-dependence of HDAC1 extraction not fully defined\", \"Cofactor involvement unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined VCP-UFD1-NPLOC4 as required for arsenic-induced degradation of PML/PML-RARA at PML bodies, recognizing SUMO/ubiquitin-modified PML.\",\n      \"evidence\": \"PML-body proteomics, p97 inhibition, siRNA, IF, PML modification analysis\",\n      \"pmids\": [\"36880596\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct extraction kinetics not measured\", \"Single lab\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Showed Ubx5-Cdc48 assists Wss1 protease in clearing DNA-protein crosslinks and degrading RNA Pol II at lesions, defining a genotoxin-induced DPC repair role.\",\n      \"evidence\": \"Yeast genetics, inducible crosslink system, ChIP, epistasis, RNAPII degradation\",\n      \"pmids\": [\"37144685\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mammalian conservation untested\", \"Order of Cdc48 versus Wss1 action partial\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Resolved bidirectional substrate shuttling between the 26S proteasome and Cdc48-UN, defining cofactor roles (Rad23, Ubx5, Shp1) in partitioning polyubiquitin binding and stimulating unfolding.\",\n      \"evidence\": \"Minimal in vitro reconstitution with purified yeast components, degradation assays, yeast genetics\",\n      \"pmids\": [\"38401542\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Regulatory logic determining handoff direction in cells unclear\", \"Mammalian cofactor equivalents not tested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified UFMylation of VCP at K109 by UFL1 as a modification promoting BECN1 stabilization, PI3K complex assembly, and autophagy initiation, linking pathogenic mutations to reduced UFMylation.\",\n      \"evidence\": \"MS site ID, mutagenesis, co-IP, BECN1 stability and LC3B reporter assays\",\n      \"pmids\": [\"38762759\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural consequence of K109 UFMylation unknown\", \"How UFMylation affects ATPase cycle untested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Showed inhibited WRN helicase is extracted by p97/VCP for degradation in MSI-H cancer cells via a PIAS4-RNF4 SUMO-ubiquitin signal, extending segregase function to a synthetic-lethal vulnerability.\",\n      \"evidence\": \"Single-molecule tracking, WRN/p97 inhibition, PIAS4/RNF4 epistasis, chromatin fractionation\",\n      \"pmids\": [\"39025847\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cofactors mediating WRN extraction not defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified VCP and a defined set of its cofactors as controllers of tau seed amplification, with opposing inhibitor effects and cofactor-specific suppression/enhancement of seeding.\",\n      \"evidence\": \"Split-APEX2 proximity labeling, CRISPR/siRNA cofactor screen, tau seeding biosensors, inhibitor pharmacology\",\n      \"pmids\": [\"39773263\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism distinguishing suppressor versus enhancer cofactors unresolved\", \"Why two inhibitors act oppositely unexplained\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How VCP's full cofactor network and post-translational modification code combine to dictate substrate choice, the clearance-versus-seeding outcome of aggregate disaggregation, and the unified mechanism by which disease mutations span ERAD, autophagy, mitochondrial, and tau pathologies remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No single framework reconciles loss-of-function versus hyperactive disease-mutant behaviors\", \"Substrate-selection logic across the cofactor repertoire not systematically defined\", \"Structural basis for most regulatory PTMs unmapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [0, 1, 2, 16, 21, 32]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 12, 13]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [4, 7, 9, 14]},\n      {\"term_id\": \"GO:0140313\", \"supporting_discovery_ids\": [5, 7, 25, 27]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [5, 7, 25, 35]},\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [5, 7, 9, 25, 27, 28]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [6, 15, 17]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [14, 19, 20, 23]},\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [21]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0, 10]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 1, 6, 17, 32]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [3, 4, 10, 19, 22, 24, 34]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [7, 8, 9, 21]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [25, 27, 28]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [5, 18, 35]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [3, 6, 12, 37]}\n    ],\n    \"complexes\": [\n      \"Cdc48-Ufd1-Npl4 (VCP-UFD1-NPLOC4) segregase\",\n      \"Cdc48-20S proteasome coaxial complex\",\n      \"VCP-clathrin-Hsc70 complex\",\n      \"ELDR lysophagy complex (VCP-UBXD1-PLAA)\"\n    ],\n    \"partners\": [\n      \"UFD1\",\n      \"NPLOC4\",\n      \"ATXN3\",\n      \"FAF1\",\n      \"UBXN1\",\n      \"WIPI2\",\n      \"UFL1\",\n      \"HDAC1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}