{"gene":"VMP1","run_date":"2026-06-11T09:02:06","timeline":{"discoveries":[{"year":2002,"finding":"VMP1 is a transmembrane protein with six hydrophobic regions that localizes to the Golgi apparatus and endoplasmic reticulum area; overexpression promotes formation of intracytoplasmic vacuoles and is located to the membranes of these vacuoles.","method":"VMP1/EGFP fusion protein localization by fluorescence microscopy; overexpression in cells","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct localization by fluorescence imaging with functional overexpression phenotype, single lab, original characterization paper","pmids":["11785947"],"is_preprint":false},{"year":2010,"finding":"VMP1 interacts with USP9x (a ubiquitin-protease) to mediate selective autophagy of activated zymogen granules (zymophagy) together with the ubiquitin-binding protein p62, preventing pancreatic cell death during pancreatitis.","method":"Co-immunoprecipitation of VMP1 with USP9x; biochemical and cellular characterization; genetic models (engineered mice and cultured acinar cells)","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and functional KD/KO with defined cellular phenotype, single lab","pmids":["21173155"],"is_preprint":false},{"year":2010,"finding":"VMP1 (Vmp1) is an ER-resident protein required for autophagosome formation in Dictyostelium; vmp1-null cells cannot survive starvation, show defects in autophagosome formation (confirmed by Atg8 colocalization), and accumulate ubiquitin-positive protein aggregates containing Atg8 and a p62 homologue.","method":"Dictyostelium vmp1 null mutant; confocal microscopy with GFP-Atg8; transmission electron microscopy; starvation survival assays","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with defined cellular phenotype and multiple orthogonal methods, single lab","pmids":["20009561"],"is_preprint":false},{"year":2013,"finding":"VMP1 induces autophagosome formation through its C-terminal 20-amino-acid hydrophilic domain (VMP1-AtgD), which directly binds the BH3 motif of Beclin 1, promotes formation of the Beclin1/hVps34 Class III PI3K complex at autophagosome formation sites, displaces the autophagy inhibitor Bcl-2 from Beclin 1, and facilitates recruitment of Atg16L1 and LC3 to autophagosomal membranes.","method":"Domain deletion/mutagenesis of VMP1-AtgD; Co-immunoprecipitation of VMP1 with Beclin1, hVps34, and Bcl-2; immunofluorescence colocalization; siRNA knockdown","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — active-site/domain mutagenesis combined with reciprocal Co-IP and cellular phenotype, multiple orthogonal methods in single study","pmids":["23316280"],"is_preprint":false},{"year":2013,"finding":"VMP1 recruits and activates the autophagy-specific Class III PI3K complex at the phagophore assembly site via its VMP1-AtgD domain binding to the BH3 domain of Beclin1, generating PtdIns3P and enabling ATG16L1 association with phagophore membranes.","method":"Co-immunoprecipitation; domain mutagenesis; immunofluorescence","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP with domain mutagenesis, single lab, corroborates concurrent Scientific Reports paper","pmids":["23558782"],"is_preprint":false},{"year":2012,"finding":"KRAS oncogene induces VMP1 expression through a PI3K-AKT1-GLI3-p300 signaling axis: GLI3 binds the VMP1 promoter and complexes with histone acetyltransferase p300 in a Hedgehog-independent manner to drive VMP1 transcription and autophagy; VMP1 is required for KRAS-induced autophagy.","method":"RNAi knockdown of KRAS and VMP1; chromatin immunoprecipitation (ChIP) assay showing GLI3 binding to VMP1 promoter; promoter activity assays; p300 knockdown; in vitro and in vivo models","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — ChIP demonstrating direct promoter binding, RNAi epistasis, promoter activity assays, multiple orthogonal methods in one study","pmids":["22535956"],"is_preprint":false},{"year":2014,"finding":"In Dictyostelium, Vmp1 is not strictly required for PtdIns3P generation but regulates its correct turnover/modulation on the ER; vmp1 null cells show elevated and aberrant PtdIns3P signaling on the ER with persistent recruitment of Atg18. Atg1 functions upstream of Vmp1 in this pathway (loss of Atg1 suppresses the aberrant PtdIns3P distribution and macropinocytosis defects of vmp1 mutants).","method":"Dictyostelium vmp1 null and double mutants (vmp1/atg1); lipid reporters for PtdIns3P; confocal microscopy; epistasis analysis","journal":"Traffic","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with multiple lipid reporter and imaging methods, single lab","pmids":["25131297"],"is_preprint":false},{"year":2016,"finding":"VMP1 localizes to ER micro-domains that are in close proximity to lipid droplets, mitochondria, and endosomes; VMP1-depleted cells display increased ER-mitochondria membrane contact sites and altered mitochondria morphology, demonstrating VMP1 regulates MCS formation.","method":"Live-cell fluorescence imaging in HeLa and Cos-7 cells; VMP1 depletion by siRNA; electron microscopy for MCS quantification","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by live imaging with functional KD phenotype quantifying MCS, single lab","pmids":["27861594"],"is_preprint":false},{"year":2017,"finding":"EPG-3/VMP1 is an ER-localized protein that controls ER-isolation membrane (IM) contacts during autophagosome formation by promoting SERCA (sarco/endoplasmic reticulum Ca2+ ATPase) activity. VMP1 physically interacts with SERCA and prevents formation of the inhibitory SERCA/PLN/SLN complex. Loss of VMP1 causes stable ER-IM association blocking autophagosome formation. Calmodulin acts as a downstream Ca2+ sensor/effector of VMP1/SERCA-mediated ER contacts. VMP1 similarly modulates ER contacts with lipid droplets, mitochondria, and endosomes.","method":"VMP1 KO cells; Co-immunoprecipitation of VMP1 with SERCA, PLN, SLN; SERCA activity assays; thapsigargin inhibitor experiments; calmodulin functional studies; electron microscopy; immunofluorescence","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods (Co-IP, enzymatic activity assay, inhibitor studies, KO phenotypes), replicated across multiple contact site types, single rigorous study","pmids":["28890335"],"is_preprint":false},{"year":2018,"finding":"VMP1/EPG-3 activates SERCA (ATP2A) to control dissociation of ER contacts with the phagophore, lipid droplets, mitochondria, and endolysosomes; calmodulin acts as a downstream Ca2+ effector that modulates PIK3C3/VPS34 PI3-kinase activity to maintain these ER contacts.","method":"VMP1 loss-of-function studies; SERCA activity assays; calmodulin functional experiments; PI3K activity measurements","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — enzymatic activity assays and functional follow-up, single lab, consistent with companion Molecular Cell paper","pmids":["29494262"],"is_preprint":false},{"year":2019,"finding":"VMP1 is required for lipoprotein release from the ER membrane; loss of vmp1 in zebrafish causes lipoprotein accumulation in the intestine and liver, and VMP1 deficiency in mice causes neutral lipid accumulation within the lipid bilayers of the ER membrane, impairing lipoprotein secretion. Other autophagy-related genes do not phenocopy this defect.","method":"Zebrafish vmp1 knockout; mouse Vmp1 knockout; lipid staining and electron microscopy of ER membrane; genetic rescue experiments comparing vmp1 to other ATG genes","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO in two vertebrate species with defined cellular and biochemical phenotypes, multiple methods, independent of autophagy pathway","pmids":["31526472"],"is_preprint":false},{"year":2019,"finding":"TMEM41B and VMP1 are physically and functionally associated; both are ER-localized multi-spanning membrane proteins that share a VTT domain, and TMEM41B functions together with VMP1 in autophagosome formation.","method":"Forward genetic CRISPR-Cas9 screen; Co-immunoprecipitation of TMEM41B and VMP1; autophagic flux reporter assay (GFP-LC3-RFP)","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and genetic screen with autophagic flux reporter, single lab","pmids":["30773971"],"is_preprint":false},{"year":2019,"finding":"The conserved glycine residue in the DedA/PF09335 domain of Vmp1 is essential for its function; substitution to leucine, glutamate, or arginine inactivates the protein, demonstrating functional relationship between VMP1 and bacterial DedA proteins.","method":"Site-directed mutagenesis of conserved glycine in Dictyostelium Vmp1; phenotypic rescue assays for development and lipid homeostasis","journal":"The International journal of developmental biology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — active-site mutagenesis with functional rescue assay, single lab, Dictyostelium model","pmids":["30785211"],"is_preprint":false},{"year":2020,"finding":"E2F1 transcription factor binds the VMP1 promoter and, together with the histone acetyltransferase EP300, regulates VMP1 expression and promoter activity in response to gemcitabine in KRAS-mutant pancreatic cancer cells.","method":"Chromatin immunoprecipitation (ChIP) demonstrating E2F1 binding to VMP1 promoter; promoter activity assays; siRNA knockdown of E2F1 and EP300","journal":"Frontiers in endocrinology","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — ChIP showing direct promoter binding plus promoter activity assays and functional knockdown, single lab","pmids":["32655498"],"is_preprint":false},{"year":2021,"finding":"In Drosophila, Vmp1 functions upstream of Vps13D and upstream of Marf/Mfn2 in a conserved pathway regulating mitochondria-ER contact sites, mitochondrial size, and clearance by autophagy; loss of marf/MFN2 suppresses vps13d mutant phenotypes including mitochondria-ER contact.","method":"Drosophila vmp1 and vps13d loss-of-function mutants; genetic epistasis (double mutants); human patient fibroblasts with VPS13D mutations; mitochondria-ER contact quantification","journal":"Current biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis in flies with confirmation in human patient cells, multiple orthogonal methods and independent validation","pmids":["34019822"],"is_preprint":false},{"year":2021,"finding":"VMP1 is required for mitophagy during acute pancreatitis; VMP1 redistributes around specific damaged mitochondrial populations, mitochondria are detected in autophagosomes isolated with anti-VMP1 antibodies, and VMP1 downregulation prevents mitochondrial degradation. A DRP1-Parkin1-VMP1 pathway mediates selective mitophagy.","method":"Co-localization studies in rat pancreatitis model; immunoisolation of VMP1-containing autophagosomes; pMITO-RFP-GFP mitophagy reporter; VMP1 knockdown; confocal microscopy","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — immunoisolation of autophagosomes plus reporter assay and KD phenotype, single lab","pmids":["33816487"],"is_preprint":false},{"year":2021,"finding":"VMP1 deficiency in dopaminergic neurons in vivo leads to impaired autophagic flux (increased LC3 puncta and p62 aggregates), large vacuolar-like structures, damaged mitochondria, swollen ER, and ubiquitin-positive aggregates, resulting in progressive loss of dopaminergic neurons and α-synuclein accumulation.","method":"Conditional neuronal VMP1 knockout mice (VMP1fl/fl/DATCreERT2); immunofluorescence; electron microscopy; behavioral assays","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean conditional KO with multiple cellular phenotype readouts in vivo, single lab","pmids":["33483473"],"is_preprint":false},{"year":2021,"finding":"Loss of VMP1 in pancreatic acinar cells leads to defective autophagic degradation, ER stress, and activation of the NFE2L2/Nrf2 pathway; genetic ablation of NFE2L2 attenuates pancreatitis in VMP1-deficient mice, placing NFE2L2 downstream of VMP1 loss.","method":"Pancreatic acinar cell-specific Vmp1 knockout mice; NFE2L2/VMP1 double knockout mice (epistasis); histological and biochemical analysis","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with double KO rescue experiment, clean conditional KO, multiple readouts, single lab","pmids":["34709991"],"is_preprint":false},{"year":2022,"finding":"VMP1 is required for DMV (double-membrane vesicle) biogenesis during β-coronavirus infection; in VMP1 KO cells, the nsp3/nsp4 complex forms normally but the zippered ER fails to close into DMVs. VMP1 regulates cross-membrane phosphatidylserine (PS) distribution, and inhibiting PS synthesis partially rescues DMV defects in VMP1 KO cells.","method":"VMP1 KO cells infected with β-coronavirus or expressing viral nsp3/nsp4; electron microscopy of DMVs; PS synthesis inhibition; comparison with TMEM41B KO cells","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with mechanistic rescue by PS inhibition, electron microscopy, multiple orthogonal approaches, single rigorous study","pmids":["35536318"],"is_preprint":false},{"year":2022,"finding":"VMP1 and TMEM41B possess a DedA domain with two predicted reentrant loops and have lipid scrambling activity; both proteins regulate the formation of ER-derived structures including autophagosomes, lipid droplets, lipoproteins, and DMVs for SARS-CoV-2 replication.","method":"Review and analysis of recent studies; scramblase activity data cited from the literature","journal":"EMBO reports","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — structural domain prediction with experimental lipid scramblase activity data referenced, review article synthesizing multiple studies","pmids":["35044051"],"is_preprint":false},{"year":2022,"finding":"Loss of hepatic VMP1 impairs VLDL secretion through decreased phosphatidylcholine and phosphatidylethanolamine levels and altered phospholipid composition, causing neutral lipid accumulation in the ER bilayer and reduced pre-VLDL assembly, leading to hepatic steatosis and NASH.","method":"Liver-specific Vmp1 knockout mice; metabolomic and transcriptome analyses; lipidomics; VLDL secretion assays; electron microscopy of ER","journal":"Journal of hepatology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean conditional KO with detailed mechanistic characterization using lipidomics, metabolomics, VLDL secretion assays, and EM, multiple methods","pmids":["35452693"],"is_preprint":false},{"year":2022,"finding":"VMP1 deficiency leads to decreased SERCA activity, increased intracellular Ca2+, mitochondrial calcium overload, mitochondrial dysfunction, and release of mitochondrial DNA, resulting in increased NLRP3 inflammasome activation and release of proinflammatory molecules.","method":"CRISPR-Cas9 deletion of VMP1 in monocytic cell line; SERCA activity assay; Ca2+ fluorescence imaging; NLRP3 inflammasome FLICA assay and biosensor; ELISA; RNA sequencing; mitochondrial function assays","journal":"Inflammation research","confidence":"High","confidence_rationale":"Tier 2 / Strong — CRISPR KO with multiple orthogonal biochemical assays (SERCA activity, Ca2+ imaging, inflammasome sensors), mechanistically detailed single study","pmids":["38411635"],"is_preprint":false},{"year":2022,"finding":"TMEM41B facilitates nsp3-nsp4 interaction and ER zippering during β-coronavirus DMV biogenesis (step 1), while VMP1 is required for the subsequent closing of the paired ER into DMVs (step 2), demonstrating the two proteins act at distinct steps.","method":"VMP1 KO and TMEM41B KO cells; electron microscopy; siRNA for PS synthesis (PTDSS1); rescue experiments","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO cells with EM and functional rescue, single lab, consistent with companion JCB paper","pmids":["35900889"],"is_preprint":false},{"year":2023,"finding":"VMP1 D272 (aspartic acid 272) is critical for its ER Ca2+ releasing activity; a D272N knockin mouse demonstrates that all VMP1 functions in T cells (preventing ER Ca2+ overload, ER stress, mitochondrial Ca2+ overload, and naive T cell apoptosis) depend on this Ca2+ regulatory function.","method":"VMP1 conditional KO in T cells; D272N knockin mouse; ER Ca2+ measurements; ER stress assays; mitochondrial Ca2+ measurements; apoptosis assays; in vivo T cell response","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — active-site mutagenesis (knockin mouse) plus clean KO, multiple physiological and biochemical readouts, in vivo validation","pmids":["36971758"],"is_preprint":false},{"year":2023,"finding":"VMP1 differentially modulates the three UPR arms: under basal conditions, Ca2+ binding specifically activates PERK; under ER stress, ER-mitochondria interaction-induced mitochondrial stress cooperates with PERK to suppress IRE1α and ATF6 by decelerating global protein synthesis, protecting cells from chronic ER stress.","method":"VMP1-deficient cells; UPR pathway reporter assays; Ca2+ chelation experiments; ER-mitochondria interaction manipulation; protein synthesis rate measurements","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO cells with multiple UPR arm-specific assays and mechanistic dissection, single lab","pmids":["36870060"],"is_preprint":false},{"year":2023,"finding":"VMP1 undergoes ubiquitination as a post-translational modification throughout autophagosome biogenesis until autolysosome formation, but VMP1 itself is not degraded by autophagy or the proteasome. The E3 ligase complex subunit Cdt2 (substrate recognition subunit of CRL4) is a novel VMP1 interactor mediating VMP1 ubiquitination; CRL4 inhibition decreases VMP1 ubiquitination and impairs VMP1 recruitment and autophagosome formation.","method":"Co-immunoprecipitation; mass spectrometry identification of Cdt2-VMP1 interaction; CRL4 inhibitor MLN4924; Cdt2 overexpression; biochemical ubiquitination assays","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and MS identification of E3 ligase plus pharmacological validation, single lab","pmids":["37629161"],"is_preprint":false},{"year":2024,"finding":"VMP1 and TMEM41B (functioning as lipid scramblases via their DedA domain) are required for primitive endoderm specification; their loss reduces FZD2 (WNT receptor) at the plasma membrane, impairing WNT signaling and XEN cell differentiation; transgenic Fzd2 expression rescues XEN differentiation.","method":"Vmp1/Tmem41b mutant mouse ESCs; WNT signaling gene expression analysis; cell surface proteome profiling; Fzd2 transgenic rescue; XEN differentiation assays","journal":"Cell death and differentiation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with proteome profiling and transgenic rescue, single lab, multiple methods","pmids":["39695329"],"is_preprint":false},{"year":2025,"finding":"VMP1 localizes at the mitochondrial-associated membrane (MAM); loss of hepatic VMP1 or TMEM41B reduces mitochondria-ER contact, decreases phosphatidylcholine and phosphatidylethanolamine, accumulates neutral lipids in the ER bilayer, and impairs VLDL secretion more severely than TMEM41B loss alone. Restoring TMEM41B in VMP1 KO mice rescues both VLDL secretion and autophagy, while restoring VMP1 in TMEM41B KO mice does not fully correct hepatic autophagy.","method":"Single and double conditional KO mice for Vmp1 and Tmem41b; lipidomic and metabolomic analyses; VLDL secretion assays; electron microscopy; knockin overexpression mice","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — comprehensive KO and rescue mouse genetics with lipidomics and EM, preprint, single lab","pmids":["40291711"],"is_preprint":true},{"year":2024,"finding":"VMP1 is secreted into the extracellular medium and incorporated into extracellular vesicle (EV) membranes (~150 nm); VMP1-EV secretion decreases with mTOR inhibition and in Atg5-deficient cells; LC3-II is detected in VMP1-EVs; VMP1 downregulation reduces LC3 and p62 secretion, demonstrating that VMP1 drives a secretory autophagy pathway.","method":"Ultracentrifugation and immunoisolation of EVs; TEM and DLS; mTOR inhibitor treatment; Atg5-deficient cells; VMP1 knockdown; rat pancreatitis model","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — EV isolation with multiple characterization methods and functional KD, preprint, single lab","pmids":["bio_10.1101_2024.10.31.615473"],"is_preprint":true},{"year":2021,"finding":"WHSC1L1 suppresses VMP1 transcription through H3K36me2-recruited DNMT3A-mediated epigenetic silencing following HSV-1 infection; VMP1 overexpression enhances mitophagy and suppresses microglial inflammatory activation, effects blocked by autophagy inhibitor 3-methyladenine.","method":"HSV-1 infection model in BV2 microglia and C57BL/6J mice; GSE35943 dataset screening; VMP1 overexpression; WHSC1L1 knockdown; autophagy inhibition; DNMT3A/H3K36me2 ChIP-based mechanistic studies","journal":"Molecular immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — epigenetic writer (WHSC1L1/DNMT3A) identified with functional validation in cells and in vivo, single lab","pmids":["37748280"],"is_preprint":false},{"year":2026,"finding":"VMP1 facilitates the recruitment of CORO1C to late endosomes, promoting Retromer-mediated recycling of the tight junction protein Occludin to the plasma membrane; VMP1 deficiency impairs this recycling, shifting Occludin trafficking toward ESCRT-dependent microautophagic degradation and resulting in tight junction loss and increased epithelial permeability.","method":"VMP1 KO in intestinal epithelial cells; Retromer recycling assays; ESCRT pathway analysis; Co-localization and trafficking studies of CORO1C and Occludin; permeability assays","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO cells with mechanistic pathway dissection (Retromer vs ESCRT trafficking), single lab","pmids":["41757559"],"is_preprint":false}],"current_model":"VMP1 is an ER-resident multi-spanning transmembrane protein with lipid scramblase activity (via its DedA domain) that promotes autophagosome formation by binding Beclin1's BH3 domain to recruit the PI3K complex, regulates ER-organelle membrane contact sites by activating SERCA to control ER calcium levels (with a critical D272 residue), mediates selective autophagy (zymophagy and mitophagy) in conjunction with USP9x/p62 and a DRP1-Parkin1 pathway, is required for lipoprotein release from the ER membrane through maintenance of phospholipid composition, supports DMV biogenesis for coronavirus replication by enabling ER membrane closure, undergoes CRL4/Cdt2-mediated ubiquitination during autophagic flux, and is transcriptionally regulated downstream of KRAS via AKT1-GLI3-p300 and E2F1-EP300 axes."},"narrative":{"mechanistic_narrative":"VMP1 is an endoplasmic reticulum-resident multi-spanning membrane protein that governs the formation and disengagement of ER-derived membranes underlying autophagy, lipid trafficking, and inter-organelle contact sites [PMID:11785947, PMID:20009561, PMID:28890335]. Through a DedA/VTT domain bearing a conserved glycine and reentrant loops, VMP1 acts as a lipid scramblase that controls transbilayer phospholipid distribution in the ER membrane [PMID:30785211, PMID:35044051]. It nucleates autophagosome formation by binding the BH3 motif of Beclin 1 via its C-terminal hydrophilic domain, displacing Bcl-2 and recruiting the Class III PI3K (Beclin1/hVps34) complex to generate PtdIns3P and enable ATG16L1 and LC3 loading at the phagophore [PMID:23316280, PMID:23558782]. A central function is the activation of the ER Ca2+ pump SERCA: VMP1 physically engages SERCA and prevents its inhibitory association with PLN/SLN, lowering local ER Ca2+ to drive dissociation of ER contacts with the isolation membrane, lipid droplets, mitochondria, and endolysosomes, with calmodulin acting as a downstream Ca2+ effector that tunes VPS34 activity [PMID:28890335, PMID:29494262]; this Ca2+-regulatory activity depends on residue D272 and underlies VMP1's protection against ER and mitochondrial Ca2+ overload [PMID:36971758]. Independent of autophagy, VMP1 maintains ER phospholipid composition (phosphatidylcholine and phosphatidylethanolamine) required for lipoprotein/VLDL release, such that its loss causes neutral lipid accumulation in the ER bilayer and hepatic steatosis [PMID:31526472, PMID:35452693]. VMP1 also enables β-coronavirus double-membrane vesicle biogenesis by mediating the closure step of zippered ER, acting downstream of TMEM41B and dependent on phosphatidylserine distribution [PMID:35536318, PMID:35900889]. Through these activities VMP1 mediates selective autophagy programs including zymophagy (with USP9x/p62) and a DRP1-Parkin-dependent mitophagy [PMID:21173155, PMID:33816487], and is transcriptionally induced by oncogenic KRAS via a PI3K-AKT1-GLI3-p300 axis [PMID:22535956]. Loss of VMP1 produces pathological consequences including pancreatitis, dopaminergic neurodegeneration with α-synuclein accumulation, and NLRP3 inflammasome activation [PMID:33483473, PMID:34709991, PMID:38411635].","teleology":[{"year":2002,"claim":"Establishing VMP1 as a transmembrane protein of the Golgi/ER compartment whose overexpression remodels intracellular membranes set the foundation for its role in membrane biogenesis.","evidence":"VMP1/EGFP fusion localization and overexpression-induced vacuole formation in cells","pmids":["11785947"],"confidence":"Medium","gaps":["No molecular function assigned","Endogenous localization vs overexpression artifact not resolved"]},{"year":2010,"claim":"Genetic and biochemical work defined VMP1 as an ER protein essential for autophagosome formation and for selective clearance of damaged organelles, linking it mechanistically to ubiquitin-binding adaptors.","evidence":"Dictyostelium vmp1-null phenotypes with GFP-Atg8/TEM, and Co-IP of VMP1 with USP9x plus p62 in pancreatic acinar models","pmids":["20009561","21173155"],"confidence":"Medium","gaps":["Direct molecular activity of VMP1 in membrane formation unknown","How VMP1 selects cargo not defined"]},{"year":2013,"claim":"Identifying the C-terminal VMP1-AtgD domain that binds Beclin 1's BH3 motif explained how VMP1 recruits and activates the autophagy-specific Class III PI3K complex at phagophore assembly sites.","evidence":"Domain deletion/mutagenesis with reciprocal Co-IP of VMP1 with Beclin1, hVps34, Bcl-2 and immunofluorescence","pmids":["23316280","23558782"],"confidence":"High","gaps":["Structural basis of the VMP1-AtgD/BH3 interface not solved","Does not address VMP1's transmembrane/scramblase contribution"]},{"year":2012,"claim":"Mapping the KRAS-PI3K-AKT1-GLI3-p300 axis onto the VMP1 promoter clarified how oncogenic signaling drives VMP1-dependent autophagy in cancer.","evidence":"RNAi epistasis, ChIP showing GLI3 promoter binding, and promoter activity assays in cancer models","pmids":["22535956"],"confidence":"High","gaps":["Other transcriptional inputs not mapped here","Hedgehog-independent GLI3 recruitment mechanism unresolved"]},{"year":2016,"claim":"Showing VMP1 at ER micro-domains contacting lipid droplets, mitochondria, and endosomes, and that its depletion increases ER-mitochondria contacts, broadened its role beyond autophagy to membrane contact site regulation.","evidence":"Live-cell imaging and EM quantification of MCS in VMP1-depleted HeLa/Cos-7 cells","pmids":["27861594"],"confidence":"Medium","gaps":["Molecular mechanism of contact-site control not yet identified","Causality vs correlation with autophagy defects unclear at this stage"]},{"year":2017,"claim":"Discovery that VMP1 activates SERCA by blocking the inhibitory SERCA/PLN/SLN complex provided the unifying Ca2+-based mechanism for ER contact dissociation during autophagosome formation and at other contact sites.","evidence":"VMP1 KO cells, Co-IP with SERCA/PLN/SLN, SERCA activity and thapsigargin assays, calmodulin studies, EM","pmids":["28890335","29494262"],"confidence":"High","gaps":["How VMP1 physically displaces PLN/SLN not structurally defined","Link between scramblase activity and SERCA regulation unresolved"]},{"year":2019,"claim":"Defining an autophagy-independent requirement for VMP1 in lipoprotein release, plus the DedA-domain glycine and TMEM41B association, recast VMP1 as a lipid-handling membrane protein.","evidence":"Zebrafish and mouse Vmp1 KO with ER lipid staining/EM and rescue comparisons; DedA glycine mutagenesis; CRISPR screen and Co-IP linking TMEM41B","pmids":["31526472","30785211","30773971"],"confidence":"High","gaps":["Direct demonstration of scramblase catalysis in VMP1 not yet shown at this point","Substrate lipid specificity undefined"]},{"year":2021,"claim":"In vivo loss-of-function across flies, mice, and pancreatitis models tied VMP1 to mitochondria-ER contact regulation, selective mitophagy, neurodegeneration, and downstream NFE2L2 stress signaling.","evidence":"Drosophila vmp1/vps13d epistasis with patient fibroblasts; DRP1-Parkin1-VMP1 mitophagy in rat pancreatitis; conditional neuronal and acinar KO mice with NFE2L2 double KO rescue","pmids":["34019822","33816487","33483473","34709991"],"confidence":"High","gaps":["Hierarchy of VMP1 within VPS13D/MFN2 pathway not fully ordered","Whether neurodegeneration is purely autophagic or also Ca2+/contact-driven unresolved"]},{"year":2022,"claim":"Demonstrating VMP1's role in ER closure for coronavirus DMV biogenesis and its scramblase-driven phospholipid control of VLDL secretion consolidated a lipid-distribution mechanism shared with TMEM41B.","evidence":"VMP1 vs TMEM41B KO cells with EM and PS-synthesis rescue; liver-specific Vmp1 KO with lipidomics and VLDL assays; DedA scramblase domain analysis","pmids":["35536318","35900889","35452693","35044051"],"confidence":"High","gaps":["In vitro reconstitution of VMP1 scramblase activity from purified protein not established","Lipid headgroup selectivity of scrambling not fully resolved"]},{"year":2023,"claim":"Pinpointing residue D272 as essential for VMP1's ER Ca2+-releasing activity, and showing UPR-arm-specific modulation and CRL4/Cdt2-mediated ubiquitination, defined the regulatory machinery controlling VMP1 function.","evidence":"D272N knockin and T-cell conditional KO mice with Ca2+/ER-stress/apoptosis readouts; UPR reporter dissection; Co-IP/MS of Cdt2 with MLN4924 validation","pmids":["36971758","36870060","37629161"],"confidence":"High","gaps":["How D272 mediates Ca2+ flux mechanistically (direct vs SERCA-coupled) not resolved","Functional consequence of VMP1 ubiquitination beyond recruitment unclear"]},{"year":2024,"claim":"Newer work extended VMP1 to developmental WNT-receptor surface delivery, Retromer-mediated tight-junction protein recycling, and secretory autophagy via extracellular vesicles.","evidence":"Vmp1/Tmem41b ESC mutants with Fzd2 rescue; VMP1 KO intestinal cells with CORO1C/Occludin trafficking assays; EV immunoisolation with mTOR/Atg5 dependence (preprint)","pmids":["39695329","41757559","37748280"],"confidence":"Medium","gaps":["Whether these phenotypes are direct or downstream of altered ER lipid/contact biology unclear","Mechanistic link between scramblase activity and endosomal recycling undefined"]},{"year":null,"claim":"It remains unresolved how VMP1's lipid scramblase activity, its SERCA/Ca2+ regulatory role, and its Beclin1-mediated PI3K recruitment are mechanistically integrated at the single-protein level.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No high-resolution structure of human VMP1 in the timeline","In vitro reconstitution coupling scramblase and Ca2+ activities not reported","Whether one domain underlies all functions or activities are separable is unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[8,9,3,4]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[19,18,20,12]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[3,4]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[0,2,7,8,10]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[27,7]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[0]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[30,7]}],"pathway":[{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[2,3,4,11,28]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[10,20,18,27]},{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[8,23,24,21]},{"term_id":"R-HSA-9709957","term_label":"Sensory Perception","supporting_discovery_ids":[18,22]}],"complexes":[],"partners":["BECN1","USP9X","SERCA/ATP2A","TMEM41B","PLN","SLN","CDT2","CORO1C"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q96GC9","full_name":"Vacuole membrane protein 1","aliases":["Transmembrane protein 49"],"length_aa":406,"mass_kda":46.2,"function":"Phospholipid scramblase involved in lipid homeostasis and membrane dynamics processes (PubMed:33850023, PubMed:33929485). Has phospholipid scramblase activity toward cholesterol and phosphatidylserine, as well as phosphatidylethanolamine and phosphatidylcholine (PubMed:33850023, PubMed:33929485). Required for autophagosome formation: participates in early stages of autophagosome biogenesis at the endoplasmic reticulum (ER) membrane by reequilibrating the leaflets of the ER as lipids are extracted by ATG2 (ATG2A or ATG2B) to mediate autophagosome assembly (PubMed:28890335, PubMed:30093494, PubMed:30933966, PubMed:33850023, PubMed:33929485). Regulates ATP2A2 activity to control ER-isolation membrane contacts for autophagosome formation (PubMed:28890335). In addition to autophagy, involved in other processes in which phospholipid scramblase activity is required (PubMed:31526472, PubMed:33850023). Modulates ER contacts with lipid droplets, mitochondria and endosomes (PubMed:28890335). Plays an essential role in formation of cell junctions (PubMed:17724469). Upon stress such as bacterial and viral infection, promotes formation of cytoplasmic vacuoles followed by cell death (By similarity). Involved in the cytoplasmic vacuolization of acinar cells during the early stage of acute pancreatitis (By similarity) (Microbial infection) Host factor required for infection by all flaviviruses tested such as Zika virus and Yellow fever virus (PubMed:33338421). Probably required post-entry of the virus to facilitate the ER membrane remodeling necessary to form replication organelles (PubMed:33338421)","subcellular_location":"Endoplasmic reticulum-Golgi intermediate compartment membrane; Cell membrane; Vacuole membrane; Endoplasmic reticulum membrane","url":"https://www.uniprot.org/uniprotkb/Q96GC9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/VMP1","classification":"Common Essential","n_dependent_lines":1183,"n_total_lines":1208,"dependency_fraction":0.9793046357615894},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000062716","cell_line_id":"CID001855","localizations":[{"compartment":"er","grade":3}],"interactors":[{"gene":"MTOR","stoichiometry":10.0}],"url":"https://opencell.sf.czbiohub.org/target/CID001855","total_profiled":1310},"omim":[{"mim_id":"620271","title":"TRANSMEMBRANE PROTEIN 41B; TMEM41B","url":"https://www.omim.org/entry/620271"},{"mim_id":"611753","title":"VACUOLE MEMBRANE PROTEIN 1; VMP1","url":"https://www.omim.org/entry/611753"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Endoplasmic reticulum","reliability":"Approved"},{"location":"Nucleoli","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/VMP1"},"hgnc":{"alias_symbol":["EPG3","TANGO5"],"prev_symbol":["TMEM49"]},"alphafold":{"accession":"Q96GC9","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96GC9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96GC9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96GC9-F1-predicted_aligned_error_v6.png","plddt_mean":78.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=VMP1","jax_strain_url":"https://www.jax.org/strain/search?query=VMP1"},"sequence":{"accession":"Q96GC9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96GC9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96GC9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96GC9"}},"corpus_meta":[{"pmid":"28890335","id":"PMC_28890335","title":"The ER-Localized Transmembrane Protein EPG-3/VMP1 Regulates SERCA Activity to Control ER-Isolation Membrane Contacts for Autophagosome Formation.","date":"2017","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/28890335","citation_count":186,"is_preprint":false},{"pmid":"21173155","id":"PMC_21173155","title":"Zymophagy, a novel selective autophagy pathway mediated by VMP1-USP9x-p62, prevents pancreatic cell death.","date":"2010","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21173155","citation_count":156,"is_preprint":false},{"pmid":"23316280","id":"PMC_23316280","title":"The VMP1-Beclin 1 interaction regulates autophagy induction.","date":"2013","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/23316280","citation_count":144,"is_preprint":false},{"pmid":"22505577","id":"PMC_22505577","title":"A novel source for miR-21 expression through the alternative polyadenylation of VMP1 gene transcripts.","date":"2012","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/22505577","citation_count":89,"is_preprint":false},{"pmid":"20299819","id":"PMC_20299819","title":"Gemcitabine induces the VMP1-mediated autophagy pathway to promote apoptotic death in human pancreatic cancer cells.","date":"2010","source":"Pancreatology : official journal of the International Association of Pancreatology (IAP) ... 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[et al.]","url":"https://pubmed.ncbi.nlm.nih.gov/12649568","citation_count":31,"is_preprint":false},{"pmid":"34019822","id":"PMC_34019822","title":"Vmp1, Vps13D, and Marf/Mfn2 function in a conserved pathway to regulate mitochondria and ER contact in development and disease.","date":"2021","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/34019822","citation_count":31,"is_preprint":false},{"pmid":"36870060","id":"PMC_36870060","title":"VMP1 affects endoplasmic reticulum stress sensitivity via differential modulation of the three unfolded protein response arms.","date":"2023","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/36870060","citation_count":29,"is_preprint":false},{"pmid":"33483473","id":"PMC_33483473","title":"Essential role for autophagy protein VMP1 in maintaining neuronal homeostasis and preventing axonal degeneration.","date":"2021","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/33483473","citation_count":28,"is_preprint":false},{"pmid":"24549370","id":"PMC_24549370","title":"Inactivation of von Hippel-Lindau increases ovarian cancer cell aggressiveness through the HIF1α/miR-210/VMP1 signaling pathway.","date":"2014","source":"International journal of molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/24549370","citation_count":28,"is_preprint":false},{"pmid":"36971758","id":"PMC_36971758","title":"VMP1 prevents Ca2+ overload in endoplasmic reticulum and maintains naive T cell survival.","date":"2023","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/36971758","citation_count":26,"is_preprint":false},{"pmid":"33816487","id":"PMC_33816487","title":"Mitochondrial Dynamics and VMP1-Related Selective Mitophagy in Experimental Acute Pancreatitis.","date":"2021","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/33816487","citation_count":26,"is_preprint":false},{"pmid":"22971212","id":"PMC_22971212","title":"Novel roles of Vmp1: inhibition metastasis and proliferation of hepatocellular carcinoma.","date":"2012","source":"Cancer science","url":"https://pubmed.ncbi.nlm.nih.gov/22971212","citation_count":26,"is_preprint":false},{"pmid":"24365149","id":"PMC_24365149","title":"VMP1 related autophagy and apoptosis in colorectal cancer cells: VMP1 regulates cell death.","date":"2013","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/24365149","citation_count":22,"is_preprint":false},{"pmid":"26328607","id":"PMC_26328607","title":"Downregulation of VMP1 confers aggressive properties to colorectal cancer.","date":"2015","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/26328607","citation_count":22,"is_preprint":false},{"pmid":"19077458","id":"PMC_19077458","title":"Autophagy and VMP1 expression are early cellular events in experimental diabetes.","date":"2008","source":"Pancreatology : official journal of the International Association of Pancreatology (IAP) ... 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overexpression promotes formation of intracytoplasmic vacuoles and is located to the membranes of these vacuoles.\",\n      \"method\": \"VMP1/EGFP fusion protein localization by fluorescence microscopy; overexpression in cells\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct localization by fluorescence imaging with functional overexpression phenotype, single lab, original characterization paper\",\n      \"pmids\": [\"11785947\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"VMP1 interacts with USP9x (a ubiquitin-protease) to mediate selective autophagy of activated zymogen granules (zymophagy) together with the ubiquitin-binding protein p62, preventing pancreatic cell death during pancreatitis.\",\n      \"method\": \"Co-immunoprecipitation of VMP1 with USP9x; biochemical and cellular characterization; genetic models (engineered mice and cultured acinar cells)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and functional KD/KO with defined cellular phenotype, single lab\",\n      \"pmids\": [\"21173155\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"VMP1 (Vmp1) is an ER-resident protein required for autophagosome formation in Dictyostelium; vmp1-null cells cannot survive starvation, show defects in autophagosome formation (confirmed by Atg8 colocalization), and accumulate ubiquitin-positive protein aggregates containing Atg8 and a p62 homologue.\",\n      \"method\": \"Dictyostelium vmp1 null mutant; confocal microscopy with GFP-Atg8; transmission electron microscopy; starvation survival assays\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with defined cellular phenotype and multiple orthogonal methods, single lab\",\n      \"pmids\": [\"20009561\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"VMP1 induces autophagosome formation through its C-terminal 20-amino-acid hydrophilic domain (VMP1-AtgD), which directly binds the BH3 motif of Beclin 1, promotes formation of the Beclin1/hVps34 Class III PI3K complex at autophagosome formation sites, displaces the autophagy inhibitor Bcl-2 from Beclin 1, and facilitates recruitment of Atg16L1 and LC3 to autophagosomal membranes.\",\n      \"method\": \"Domain deletion/mutagenesis of VMP1-AtgD; Co-immunoprecipitation of VMP1 with Beclin1, hVps34, and Bcl-2; immunofluorescence colocalization; siRNA knockdown\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — active-site/domain mutagenesis combined with reciprocal Co-IP and cellular phenotype, multiple orthogonal methods in single study\",\n      \"pmids\": [\"23316280\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"VMP1 recruits and activates the autophagy-specific Class III PI3K complex at the phagophore assembly site via its VMP1-AtgD domain binding to the BH3 domain of Beclin1, generating PtdIns3P and enabling ATG16L1 association with phagophore membranes.\",\n      \"method\": \"Co-immunoprecipitation; domain mutagenesis; immunofluorescence\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP with domain mutagenesis, single lab, corroborates concurrent Scientific Reports paper\",\n      \"pmids\": [\"23558782\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"KRAS oncogene induces VMP1 expression through a PI3K-AKT1-GLI3-p300 signaling axis: GLI3 binds the VMP1 promoter and complexes with histone acetyltransferase p300 in a Hedgehog-independent manner to drive VMP1 transcription and autophagy; VMP1 is required for KRAS-induced autophagy.\",\n      \"method\": \"RNAi knockdown of KRAS and VMP1; chromatin immunoprecipitation (ChIP) assay showing GLI3 binding to VMP1 promoter; promoter activity assays; p300 knockdown; in vitro and in vivo models\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — ChIP demonstrating direct promoter binding, RNAi epistasis, promoter activity assays, multiple orthogonal methods in one study\",\n      \"pmids\": [\"22535956\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"In Dictyostelium, Vmp1 is not strictly required for PtdIns3P generation but regulates its correct turnover/modulation on the ER; vmp1 null cells show elevated and aberrant PtdIns3P signaling on the ER with persistent recruitment of Atg18. Atg1 functions upstream of Vmp1 in this pathway (loss of Atg1 suppresses the aberrant PtdIns3P distribution and macropinocytosis defects of vmp1 mutants).\",\n      \"method\": \"Dictyostelium vmp1 null and double mutants (vmp1/atg1); lipid reporters for PtdIns3P; confocal microscopy; epistasis analysis\",\n      \"journal\": \"Traffic\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with multiple lipid reporter and imaging methods, single lab\",\n      \"pmids\": [\"25131297\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"VMP1 localizes to ER micro-domains that are in close proximity to lipid droplets, mitochondria, and endosomes; VMP1-depleted cells display increased ER-mitochondria membrane contact sites and altered mitochondria morphology, demonstrating VMP1 regulates MCS formation.\",\n      \"method\": \"Live-cell fluorescence imaging in HeLa and Cos-7 cells; VMP1 depletion by siRNA; electron microscopy for MCS quantification\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by live imaging with functional KD phenotype quantifying MCS, single lab\",\n      \"pmids\": [\"27861594\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"EPG-3/VMP1 is an ER-localized protein that controls ER-isolation membrane (IM) contacts during autophagosome formation by promoting SERCA (sarco/endoplasmic reticulum Ca2+ ATPase) activity. VMP1 physically interacts with SERCA and prevents formation of the inhibitory SERCA/PLN/SLN complex. Loss of VMP1 causes stable ER-IM association blocking autophagosome formation. Calmodulin acts as a downstream Ca2+ sensor/effector of VMP1/SERCA-mediated ER contacts. VMP1 similarly modulates ER contacts with lipid droplets, mitochondria, and endosomes.\",\n      \"method\": \"VMP1 KO cells; Co-immunoprecipitation of VMP1 with SERCA, PLN, SLN; SERCA activity assays; thapsigargin inhibitor experiments; calmodulin functional studies; electron microscopy; immunofluorescence\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods (Co-IP, enzymatic activity assay, inhibitor studies, KO phenotypes), replicated across multiple contact site types, single rigorous study\",\n      \"pmids\": [\"28890335\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"VMP1/EPG-3 activates SERCA (ATP2A) to control dissociation of ER contacts with the phagophore, lipid droplets, mitochondria, and endolysosomes; calmodulin acts as a downstream Ca2+ effector that modulates PIK3C3/VPS34 PI3-kinase activity to maintain these ER contacts.\",\n      \"method\": \"VMP1 loss-of-function studies; SERCA activity assays; calmodulin functional experiments; PI3K activity measurements\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — enzymatic activity assays and functional follow-up, single lab, consistent with companion Molecular Cell paper\",\n      \"pmids\": [\"29494262\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"VMP1 is required for lipoprotein release from the ER membrane; loss of vmp1 in zebrafish causes lipoprotein accumulation in the intestine and liver, and VMP1 deficiency in mice causes neutral lipid accumulation within the lipid bilayers of the ER membrane, impairing lipoprotein secretion. Other autophagy-related genes do not phenocopy this defect.\",\n      \"method\": \"Zebrafish vmp1 knockout; mouse Vmp1 knockout; lipid staining and electron microscopy of ER membrane; genetic rescue experiments comparing vmp1 to other ATG genes\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO in two vertebrate species with defined cellular and biochemical phenotypes, multiple methods, independent of autophagy pathway\",\n      \"pmids\": [\"31526472\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"TMEM41B and VMP1 are physically and functionally associated; both are ER-localized multi-spanning membrane proteins that share a VTT domain, and TMEM41B functions together with VMP1 in autophagosome formation.\",\n      \"method\": \"Forward genetic CRISPR-Cas9 screen; Co-immunoprecipitation of TMEM41B and VMP1; autophagic flux reporter assay (GFP-LC3-RFP)\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and genetic screen with autophagic flux reporter, single lab\",\n      \"pmids\": [\"30773971\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The conserved glycine residue in the DedA/PF09335 domain of Vmp1 is essential for its function; substitution to leucine, glutamate, or arginine inactivates the protein, demonstrating functional relationship between VMP1 and bacterial DedA proteins.\",\n      \"method\": \"Site-directed mutagenesis of conserved glycine in Dictyostelium Vmp1; phenotypic rescue assays for development and lipid homeostasis\",\n      \"journal\": \"The International journal of developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — active-site mutagenesis with functional rescue assay, single lab, Dictyostelium model\",\n      \"pmids\": [\"30785211\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"E2F1 transcription factor binds the VMP1 promoter and, together with the histone acetyltransferase EP300, regulates VMP1 expression and promoter activity in response to gemcitabine in KRAS-mutant pancreatic cancer cells.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP) demonstrating E2F1 binding to VMP1 promoter; promoter activity assays; siRNA knockdown of E2F1 and EP300\",\n      \"journal\": \"Frontiers in endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — ChIP showing direct promoter binding plus promoter activity assays and functional knockdown, single lab\",\n      \"pmids\": [\"32655498\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In Drosophila, Vmp1 functions upstream of Vps13D and upstream of Marf/Mfn2 in a conserved pathway regulating mitochondria-ER contact sites, mitochondrial size, and clearance by autophagy; loss of marf/MFN2 suppresses vps13d mutant phenotypes including mitochondria-ER contact.\",\n      \"method\": \"Drosophila vmp1 and vps13d loss-of-function mutants; genetic epistasis (double mutants); human patient fibroblasts with VPS13D mutations; mitochondria-ER contact quantification\",\n      \"journal\": \"Current biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis in flies with confirmation in human patient cells, multiple orthogonal methods and independent validation\",\n      \"pmids\": [\"34019822\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"VMP1 is required for mitophagy during acute pancreatitis; VMP1 redistributes around specific damaged mitochondrial populations, mitochondria are detected in autophagosomes isolated with anti-VMP1 antibodies, and VMP1 downregulation prevents mitochondrial degradation. A DRP1-Parkin1-VMP1 pathway mediates selective mitophagy.\",\n      \"method\": \"Co-localization studies in rat pancreatitis model; immunoisolation of VMP1-containing autophagosomes; pMITO-RFP-GFP mitophagy reporter; VMP1 knockdown; confocal microscopy\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — immunoisolation of autophagosomes plus reporter assay and KD phenotype, single lab\",\n      \"pmids\": [\"33816487\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"VMP1 deficiency in dopaminergic neurons in vivo leads to impaired autophagic flux (increased LC3 puncta and p62 aggregates), large vacuolar-like structures, damaged mitochondria, swollen ER, and ubiquitin-positive aggregates, resulting in progressive loss of dopaminergic neurons and α-synuclein accumulation.\",\n      \"method\": \"Conditional neuronal VMP1 knockout mice (VMP1fl/fl/DATCreERT2); immunofluorescence; electron microscopy; behavioral assays\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean conditional KO with multiple cellular phenotype readouts in vivo, single lab\",\n      \"pmids\": [\"33483473\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Loss of VMP1 in pancreatic acinar cells leads to defective autophagic degradation, ER stress, and activation of the NFE2L2/Nrf2 pathway; genetic ablation of NFE2L2 attenuates pancreatitis in VMP1-deficient mice, placing NFE2L2 downstream of VMP1 loss.\",\n      \"method\": \"Pancreatic acinar cell-specific Vmp1 knockout mice; NFE2L2/VMP1 double knockout mice (epistasis); histological and biochemical analysis\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with double KO rescue experiment, clean conditional KO, multiple readouts, single lab\",\n      \"pmids\": [\"34709991\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"VMP1 is required for DMV (double-membrane vesicle) biogenesis during β-coronavirus infection; in VMP1 KO cells, the nsp3/nsp4 complex forms normally but the zippered ER fails to close into DMVs. VMP1 regulates cross-membrane phosphatidylserine (PS) distribution, and inhibiting PS synthesis partially rescues DMV defects in VMP1 KO cells.\",\n      \"method\": \"VMP1 KO cells infected with β-coronavirus or expressing viral nsp3/nsp4; electron microscopy of DMVs; PS synthesis inhibition; comparison with TMEM41B KO cells\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with mechanistic rescue by PS inhibition, electron microscopy, multiple orthogonal approaches, single rigorous study\",\n      \"pmids\": [\"35536318\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"VMP1 and TMEM41B possess a DedA domain with two predicted reentrant loops and have lipid scrambling activity; both proteins regulate the formation of ER-derived structures including autophagosomes, lipid droplets, lipoproteins, and DMVs for SARS-CoV-2 replication.\",\n      \"method\": \"Review and analysis of recent studies; scramblase activity data cited from the literature\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — structural domain prediction with experimental lipid scramblase activity data referenced, review article synthesizing multiple studies\",\n      \"pmids\": [\"35044051\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Loss of hepatic VMP1 impairs VLDL secretion through decreased phosphatidylcholine and phosphatidylethanolamine levels and altered phospholipid composition, causing neutral lipid accumulation in the ER bilayer and reduced pre-VLDL assembly, leading to hepatic steatosis and NASH.\",\n      \"method\": \"Liver-specific Vmp1 knockout mice; metabolomic and transcriptome analyses; lipidomics; VLDL secretion assays; electron microscopy of ER\",\n      \"journal\": \"Journal of hepatology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean conditional KO with detailed mechanistic characterization using lipidomics, metabolomics, VLDL secretion assays, and EM, multiple methods\",\n      \"pmids\": [\"35452693\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"VMP1 deficiency leads to decreased SERCA activity, increased intracellular Ca2+, mitochondrial calcium overload, mitochondrial dysfunction, and release of mitochondrial DNA, resulting in increased NLRP3 inflammasome activation and release of proinflammatory molecules.\",\n      \"method\": \"CRISPR-Cas9 deletion of VMP1 in monocytic cell line; SERCA activity assay; Ca2+ fluorescence imaging; NLRP3 inflammasome FLICA assay and biosensor; ELISA; RNA sequencing; mitochondrial function assays\",\n      \"journal\": \"Inflammation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — CRISPR KO with multiple orthogonal biochemical assays (SERCA activity, Ca2+ imaging, inflammasome sensors), mechanistically detailed single study\",\n      \"pmids\": [\"38411635\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TMEM41B facilitates nsp3-nsp4 interaction and ER zippering during β-coronavirus DMV biogenesis (step 1), while VMP1 is required for the subsequent closing of the paired ER into DMVs (step 2), demonstrating the two proteins act at distinct steps.\",\n      \"method\": \"VMP1 KO and TMEM41B KO cells; electron microscopy; siRNA for PS synthesis (PTDSS1); rescue experiments\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO cells with EM and functional rescue, single lab, consistent with companion JCB paper\",\n      \"pmids\": [\"35900889\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"VMP1 D272 (aspartic acid 272) is critical for its ER Ca2+ releasing activity; a D272N knockin mouse demonstrates that all VMP1 functions in T cells (preventing ER Ca2+ overload, ER stress, mitochondrial Ca2+ overload, and naive T cell apoptosis) depend on this Ca2+ regulatory function.\",\n      \"method\": \"VMP1 conditional KO in T cells; D272N knockin mouse; ER Ca2+ measurements; ER stress assays; mitochondrial Ca2+ measurements; apoptosis assays; in vivo T cell response\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — active-site mutagenesis (knockin mouse) plus clean KO, multiple physiological and biochemical readouts, in vivo validation\",\n      \"pmids\": [\"36971758\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"VMP1 differentially modulates the three UPR arms: under basal conditions, Ca2+ binding specifically activates PERK; under ER stress, ER-mitochondria interaction-induced mitochondrial stress cooperates with PERK to suppress IRE1α and ATF6 by decelerating global protein synthesis, protecting cells from chronic ER stress.\",\n      \"method\": \"VMP1-deficient cells; UPR pathway reporter assays; Ca2+ chelation experiments; ER-mitochondria interaction manipulation; protein synthesis rate measurements\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO cells with multiple UPR arm-specific assays and mechanistic dissection, single lab\",\n      \"pmids\": [\"36870060\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"VMP1 undergoes ubiquitination as a post-translational modification throughout autophagosome biogenesis until autolysosome formation, but VMP1 itself is not degraded by autophagy or the proteasome. The E3 ligase complex subunit Cdt2 (substrate recognition subunit of CRL4) is a novel VMP1 interactor mediating VMP1 ubiquitination; CRL4 inhibition decreases VMP1 ubiquitination and impairs VMP1 recruitment and autophagosome formation.\",\n      \"method\": \"Co-immunoprecipitation; mass spectrometry identification of Cdt2-VMP1 interaction; CRL4 inhibitor MLN4924; Cdt2 overexpression; biochemical ubiquitination assays\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and MS identification of E3 ligase plus pharmacological validation, single lab\",\n      \"pmids\": [\"37629161\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"VMP1 and TMEM41B (functioning as lipid scramblases via their DedA domain) are required for primitive endoderm specification; their loss reduces FZD2 (WNT receptor) at the plasma membrane, impairing WNT signaling and XEN cell differentiation; transgenic Fzd2 expression rescues XEN differentiation.\",\n      \"method\": \"Vmp1/Tmem41b mutant mouse ESCs; WNT signaling gene expression analysis; cell surface proteome profiling; Fzd2 transgenic rescue; XEN differentiation assays\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with proteome profiling and transgenic rescue, single lab, multiple methods\",\n      \"pmids\": [\"39695329\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"VMP1 localizes at the mitochondrial-associated membrane (MAM); loss of hepatic VMP1 or TMEM41B reduces mitochondria-ER contact, decreases phosphatidylcholine and phosphatidylethanolamine, accumulates neutral lipids in the ER bilayer, and impairs VLDL secretion more severely than TMEM41B loss alone. Restoring TMEM41B in VMP1 KO mice rescues both VLDL secretion and autophagy, while restoring VMP1 in TMEM41B KO mice does not fully correct hepatic autophagy.\",\n      \"method\": \"Single and double conditional KO mice for Vmp1 and Tmem41b; lipidomic and metabolomic analyses; VLDL secretion assays; electron microscopy; knockin overexpression mice\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — comprehensive KO and rescue mouse genetics with lipidomics and EM, preprint, single lab\",\n      \"pmids\": [\"40291711\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"VMP1 is secreted into the extracellular medium and incorporated into extracellular vesicle (EV) membranes (~150 nm); VMP1-EV secretion decreases with mTOR inhibition and in Atg5-deficient cells; LC3-II is detected in VMP1-EVs; VMP1 downregulation reduces LC3 and p62 secretion, demonstrating that VMP1 drives a secretory autophagy pathway.\",\n      \"method\": \"Ultracentrifugation and immunoisolation of EVs; TEM and DLS; mTOR inhibitor treatment; Atg5-deficient cells; VMP1 knockdown; rat pancreatitis model\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — EV isolation with multiple characterization methods and functional KD, preprint, single lab\",\n      \"pmids\": [\"bio_10.1101_2024.10.31.615473\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"WHSC1L1 suppresses VMP1 transcription through H3K36me2-recruited DNMT3A-mediated epigenetic silencing following HSV-1 infection; VMP1 overexpression enhances mitophagy and suppresses microglial inflammatory activation, effects blocked by autophagy inhibitor 3-methyladenine.\",\n      \"method\": \"HSV-1 infection model in BV2 microglia and C57BL/6J mice; GSE35943 dataset screening; VMP1 overexpression; WHSC1L1 knockdown; autophagy inhibition; DNMT3A/H3K36me2 ChIP-based mechanistic studies\",\n      \"journal\": \"Molecular immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — epigenetic writer (WHSC1L1/DNMT3A) identified with functional validation in cells and in vivo, single lab\",\n      \"pmids\": [\"37748280\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"VMP1 facilitates the recruitment of CORO1C to late endosomes, promoting Retromer-mediated recycling of the tight junction protein Occludin to the plasma membrane; VMP1 deficiency impairs this recycling, shifting Occludin trafficking toward ESCRT-dependent microautophagic degradation and resulting in tight junction loss and increased epithelial permeability.\",\n      \"method\": \"VMP1 KO in intestinal epithelial cells; Retromer recycling assays; ESCRT pathway analysis; Co-localization and trafficking studies of CORO1C and Occludin; permeability assays\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO cells with mechanistic pathway dissection (Retromer vs ESCRT trafficking), single lab\",\n      \"pmids\": [\"41757559\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"VMP1 is an ER-resident multi-spanning transmembrane protein with lipid scramblase activity (via its DedA domain) that promotes autophagosome formation by binding Beclin1's BH3 domain to recruit the PI3K complex, regulates ER-organelle membrane contact sites by activating SERCA to control ER calcium levels (with a critical D272 residue), mediates selective autophagy (zymophagy and mitophagy) in conjunction with USP9x/p62 and a DRP1-Parkin1 pathway, is required for lipoprotein release from the ER membrane through maintenance of phospholipid composition, supports DMV biogenesis for coronavirus replication by enabling ER membrane closure, undergoes CRL4/Cdt2-mediated ubiquitination during autophagic flux, and is transcriptionally regulated downstream of KRAS via AKT1-GLI3-p300 and E2F1-EP300 axes.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"VMP1 is an endoplasmic reticulum-resident multi-spanning membrane protein that governs the formation and disengagement of ER-derived membranes underlying autophagy, lipid trafficking, and inter-organelle contact sites [#0, #2, #8]. Through a DedA/VTT domain bearing a conserved glycine and reentrant loops, VMP1 acts as a lipid scramblase that controls transbilayer phospholipid distribution in the ER membrane [#12, #19]. It nucleates autophagosome formation by binding the BH3 motif of Beclin 1 via its C-terminal hydrophilic domain, displacing Bcl-2 and recruiting the Class III PI3K (Beclin1/hVps34) complex to generate PtdIns3P and enable ATG16L1 and LC3 loading at the phagophore [#3, #4]. A central function is the activation of the ER Ca2+ pump SERCA: VMP1 physically engages SERCA and prevents its inhibitory association with PLN/SLN, lowering local ER Ca2+ to drive dissociation of ER contacts with the isolation membrane, lipid droplets, mitochondria, and endolysosomes, with calmodulin acting as a downstream Ca2+ effector that tunes VPS34 activity [#8, #9]; this Ca2+-regulatory activity depends on residue D272 and underlies VMP1's protection against ER and mitochondrial Ca2+ overload [#23]. Independent of autophagy, VMP1 maintains ER phospholipid composition (phosphatidylcholine and phosphatidylethanolamine) required for lipoprotein/VLDL release, such that its loss causes neutral lipid accumulation in the ER bilayer and hepatic steatosis [#10, #20]. VMP1 also enables β-coronavirus double-membrane vesicle biogenesis by mediating the closure step of zippered ER, acting downstream of TMEM41B and dependent on phosphatidylserine distribution [#18, #22]. Through these activities VMP1 mediates selective autophagy programs including zymophagy (with USP9x/p62) and a DRP1-Parkin-dependent mitophagy [#1, #15], and is transcriptionally induced by oncogenic KRAS via a PI3K-AKT1-GLI3-p300 axis [#5]. Loss of VMP1 produces pathological consequences including pancreatitis, dopaminergic neurodegeneration with α-synuclein accumulation, and NLRP3 inflammasome activation [#16, #17, #21].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Establishing VMP1 as a transmembrane protein of the Golgi/ER compartment whose overexpression remodels intracellular membranes set the foundation for its role in membrane biogenesis.\",\n      \"evidence\": \"VMP1/EGFP fusion localization and overexpression-induced vacuole formation in cells\",\n      \"pmids\": [\"11785947\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No molecular function assigned\", \"Endogenous localization vs overexpression artifact not resolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Genetic and biochemical work defined VMP1 as an ER protein essential for autophagosome formation and for selective clearance of damaged organelles, linking it mechanistically to ubiquitin-binding adaptors.\",\n      \"evidence\": \"Dictyostelium vmp1-null phenotypes with GFP-Atg8/TEM, and Co-IP of VMP1 with USP9x plus p62 in pancreatic acinar models\",\n      \"pmids\": [\"20009561\", \"21173155\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular activity of VMP1 in membrane formation unknown\", \"How VMP1 selects cargo not defined\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identifying the C-terminal VMP1-AtgD domain that binds Beclin 1's BH3 motif explained how VMP1 recruits and activates the autophagy-specific Class III PI3K complex at phagophore assembly sites.\",\n      \"evidence\": \"Domain deletion/mutagenesis with reciprocal Co-IP of VMP1 with Beclin1, hVps34, Bcl-2 and immunofluorescence\",\n      \"pmids\": [\"23316280\", \"23558782\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the VMP1-AtgD/BH3 interface not solved\", \"Does not address VMP1's transmembrane/scramblase contribution\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Mapping the KRAS-PI3K-AKT1-GLI3-p300 axis onto the VMP1 promoter clarified how oncogenic signaling drives VMP1-dependent autophagy in cancer.\",\n      \"evidence\": \"RNAi epistasis, ChIP showing GLI3 promoter binding, and promoter activity assays in cancer models\",\n      \"pmids\": [\"22535956\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Other transcriptional inputs not mapped here\", \"Hedgehog-independent GLI3 recruitment mechanism unresolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showing VMP1 at ER micro-domains contacting lipid droplets, mitochondria, and endosomes, and that its depletion increases ER-mitochondria contacts, broadened its role beyond autophagy to membrane contact site regulation.\",\n      \"evidence\": \"Live-cell imaging and EM quantification of MCS in VMP1-depleted HeLa/Cos-7 cells\",\n      \"pmids\": [\"27861594\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular mechanism of contact-site control not yet identified\", \"Causality vs correlation with autophagy defects unclear at this stage\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Discovery that VMP1 activates SERCA by blocking the inhibitory SERCA/PLN/SLN complex provided the unifying Ca2+-based mechanism for ER contact dissociation during autophagosome formation and at other contact sites.\",\n      \"evidence\": \"VMP1 KO cells, Co-IP with SERCA/PLN/SLN, SERCA activity and thapsigargin assays, calmodulin studies, EM\",\n      \"pmids\": [\"28890335\", \"29494262\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How VMP1 physically displaces PLN/SLN not structurally defined\", \"Link between scramblase activity and SERCA regulation unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defining an autophagy-independent requirement for VMP1 in lipoprotein release, plus the DedA-domain glycine and TMEM41B association, recast VMP1 as a lipid-handling membrane protein.\",\n      \"evidence\": \"Zebrafish and mouse Vmp1 KO with ER lipid staining/EM and rescue comparisons; DedA glycine mutagenesis; CRISPR screen and Co-IP linking TMEM41B\",\n      \"pmids\": [\"31526472\", \"30785211\", \"30773971\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct demonstration of scramblase catalysis in VMP1 not yet shown at this point\", \"Substrate lipid specificity undefined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"In vivo loss-of-function across flies, mice, and pancreatitis models tied VMP1 to mitochondria-ER contact regulation, selective mitophagy, neurodegeneration, and downstream NFE2L2 stress signaling.\",\n      \"evidence\": \"Drosophila vmp1/vps13d epistasis with patient fibroblasts; DRP1-Parkin1-VMP1 mitophagy in rat pancreatitis; conditional neuronal and acinar KO mice with NFE2L2 double KO rescue\",\n      \"pmids\": [\"34019822\", \"33816487\", \"33483473\", \"34709991\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Hierarchy of VMP1 within VPS13D/MFN2 pathway not fully ordered\", \"Whether neurodegeneration is purely autophagic or also Ca2+/contact-driven unresolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrating VMP1's role in ER closure for coronavirus DMV biogenesis and its scramblase-driven phospholipid control of VLDL secretion consolidated a lipid-distribution mechanism shared with TMEM41B.\",\n      \"evidence\": \"VMP1 vs TMEM41B KO cells with EM and PS-synthesis rescue; liver-specific Vmp1 KO with lipidomics and VLDL assays; DedA scramblase domain analysis\",\n      \"pmids\": [\"35536318\", \"35900889\", \"35452693\", \"35044051\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vitro reconstitution of VMP1 scramblase activity from purified protein not established\", \"Lipid headgroup selectivity of scrambling not fully resolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Pinpointing residue D272 as essential for VMP1's ER Ca2+-releasing activity, and showing UPR-arm-specific modulation and CRL4/Cdt2-mediated ubiquitination, defined the regulatory machinery controlling VMP1 function.\",\n      \"evidence\": \"D272N knockin and T-cell conditional KO mice with Ca2+/ER-stress/apoptosis readouts; UPR reporter dissection; Co-IP/MS of Cdt2 with MLN4924 validation\",\n      \"pmids\": [\"36971758\", \"36870060\", \"37629161\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How D272 mediates Ca2+ flux mechanistically (direct vs SERCA-coupled) not resolved\", \"Functional consequence of VMP1 ubiquitination beyond recruitment unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Newer work extended VMP1 to developmental WNT-receptor surface delivery, Retromer-mediated tight-junction protein recycling, and secretory autophagy via extracellular vesicles.\",\n      \"evidence\": \"Vmp1/Tmem41b ESC mutants with Fzd2 rescue; VMP1 KO intestinal cells with CORO1C/Occludin trafficking assays; EV immunoisolation with mTOR/Atg5 dependence (preprint)\",\n      \"pmids\": [\"39695329\", \"41757559\", \"37748280\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether these phenotypes are direct or downstream of altered ER lipid/contact biology unclear\", \"Mechanistic link between scramblase activity and endosomal recycling undefined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how VMP1's lipid scramblase activity, its SERCA/Ca2+ regulatory role, and its Beclin1-mediated PI3K recruitment are mechanistically integrated at the single-protein level.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No high-resolution structure of human VMP1 in the timeline\", \"In vitro reconstitution coupling scramblase and Ca2+ activities not reported\", \"Whether one domain underlies all functions or activities are separable is unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [8, 9, 3, 4]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [19, 18, 20, 12]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [3, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [0, 2, 7, 8, 10]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [27, 7]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [30, 7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [2, 3, 4, 11, 28]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [10, 20, 18, 27]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [8, 23, 24, 21]},\n      {\"term_id\": \"R-HSA-9709957\", \"supporting_discovery_ids\": [18, 22]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"BECN1\", \"USP9x\", \"SERCA/ATP2A\", \"TMEM41B\", \"PLN\", \"SLN\", \"Cdt2\", \"CORO1C\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}