{"gene":"HGS","run_date":"2026-06-10T01:55:22","timeline":{"discoveries":[{"year":2003,"finding":"Vps27 (HGS ortholog) recruits ESCRT-I to endosomal membranes through direct binding via a PTVP-containing motif in its C-terminus; FYVE domain-mediated binding to phosphatidylinositol 3-phosphate provides compartmental specificity for the MVB sorting reaction, and both interactions are required for ubiquitinated cargo sorting into MVBs.","method":"Yeast genetics, in vivo binding assays, mutational analysis of PTVP motif, lipid-binding assays","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (genetic, biochemical, mutational), replicated across labs in yeast and mammalian systems","pmids":["12900393"],"is_preprint":false},{"year":1995,"finding":"Vps27 controls membrane trafficking through the prevacuolar/endosomal compartment: rapid inactivation of Vps27p causes Golgi recycling proteins (Vps10p) and endocytosed proteins (Ste3p) to accumulate in a class E compartment, and restoration of Vps27p function allows transit to resume, establishing the prevacuolar compartment as a functional intermediate for both biosynthetic and endocytic pathways.","method":"Temperature-sensitive allele of VPS27, fluorescence microscopy, protein trafficking assays","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional loss-of-function with defined molecular phenotypes, multiple cargo proteins tested, replicated by restoration-of-function experiment","pmids":["7593183"],"is_preprint":false},{"year":2003,"finding":"The individual UIMs of Vps27 fold as autonomous alpha-helices that each independently bind ubiquitin via the Leu8-Ile44-Val70 hydrophobic patch; both UIMs are required for efficient ubiquitin interactions and MVB cargo sorting. The binding surface is conserved with other ubiquitin-binding endocytic proteins (S5a, CUE, UBA domains).","method":"NMR solution structure, mutagenesis, in vitro binding assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — NMR structure with mutagenesis validation, defines atomic-level interaction surface","pmids":["12970172"],"is_preprint":false},{"year":2003,"finding":"Vps27 forms a complex with Hse1; together they act as a ubiquitin-sorting receptor at endosomes. Vps27 binds Vps23 (ESCRT-I) directly via two PSDP motifs in its C-terminus. Disruption of Vps27-Hse1 interaction causes severe MVB sorting defects, while loss of Vps27-Vps23 interaction reduces sorting efficiency without abolishing MVB formation. Both the Vps27 and Vps23 ubiquitin-binding surfaces contact the same cargo ubiquitin.","method":"NMR spectroscopy, mutagenesis, yeast genetics, MVB sorting assays","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — NMR mapping combined with genetic epistasis and functional sorting assays, multiple complementary approaches","pmids":["14581452"],"is_preprint":false},{"year":2007,"finding":"Crystal structure of the Vps27/Hse1 complex core at 3.0 Å resolution reveals two intertwined GAT domains (each formed by two helices from one subunit and one from the other) connected by an antiparallel coiled coil forming a 90 Å barbell-like scaffold. This architecture positions domains that recruit ubiquitinated cargo and deubiquitinating enzymes in proximity; Monte Carlo simulations show cooperative binding to lipids and ubiquitinated membrane proteins.","method":"X-ray crystallography (3.0 Å), sedimentation equilibrium, coarse-grained Monte Carlo simulations","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with functional domain placement, single study but rigorous structural method","pmids":["17543868"],"is_preprint":false},{"year":2000,"finding":"HGS (Hgs) binds Smad2 via its C-terminal half and cooperates with SARA to stimulate activin receptor-mediated signaling by efficiently recruiting Smad2 to the TGF-β/activin receptor complex. A C-terminal deletion knock-in mouse is embryonic lethal (E8.5–10.5) and mutant cells show significantly decreased responses to activin and TGF-β stimulation.","method":"Co-immunoprecipitation, gene targeting (knock-in), reporter assays, cell stimulation assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding assays combined with in vivo genetic loss-of-function showing defined signaling phenotype","pmids":["11094085"],"is_preprint":false},{"year":2002,"finding":"HGS localizes to early endosomes via its FYVE/lipid-binding domain, which is necessary for constitutive EGFR endocytosis. The ubiquitin-interacting motif (UIM) of HGS has dual function: it binds ubiquitylated proteins AND recruits Nedd4 ubiquitin ligase to promote self-ubiquitylation of HGS, thereby negatively regulating receptor degradation.","method":"Co-immunoprecipitation, dominant-negative overexpression, immunofluorescence/endosome fractionation, domain deletion analysis","journal":"Traffic (Copenhagen, Denmark)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple functional domains tested with defined phenotypes, single lab, two orthogonal approaches (binding and functional assays)","pmids":["12230472"],"is_preprint":false},{"year":2001,"finding":"HGS physically associates with TAK1 (TGF-β-activated kinase 1) and Pak1 (p21-activated kinase 1), and is required for IL-2-induced activation of the serum-response element and CRE of the c-fos promoter through the TAK1-JNK and Pak1-SRF pathways.","method":"Co-immunoprecipitation, reporter gene assays (SRE, CRE of c-fos), dominant-negative constructs","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — physical interaction confirmed by Co-IP with functional reporter assays, single lab","pmids":["11397816"],"is_preprint":false},{"year":2011,"finding":"HGS is required for phosphorylation of SMAD1/5/8 and TAK1/p38 to transduce BMP signaling during early mouse embryo development. HGS functions to localize TAK1 to the early endosome for its activation; Hgs-mutant embryos show highly down-regulated BMP target genes.","method":"Mouse knockout genetics, western blot (phospho-SMAD1/5/8, phospho-TAK1/p38), immunofluorescence localization of TAK1","journal":"Developmental dynamics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo genetic loss-of-function with biochemical endpoint, single lab","pmids":["21953618"],"is_preprint":false},{"year":2006,"finding":"HGS (Hgs) directly interacts with Smad5 (identified via cDNA library screen and confirmed by co-immunoprecipitation) and overexpression of Hgs attenuates BMP-dependent transcriptional responses, establishing HGS as an inhibitor of BMP signaling.","method":"cDNA expression library screen, co-immunoprecipitation, BMP-responsive reporter gene assay","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP and functional reporter assay, single lab, two orthogonal methods","pmids":["16516194"],"is_preprint":false},{"year":2012,"finding":"Pkh1/Pkh2 kinases (yeast orthologs of PDK1) directly phosphorylate Vps27 at serine 613 both in vivo and in vitro; this phosphorylation is required for proper ESCRT-I (Vps28) recruitment to endosomes. vps27-S613A mutant cells show impaired MVB sorting of Cps1 and Ste2, and ESCRT-I remains mainly cytoplasmic.","method":"In vitro kinase assay, site-directed mutagenesis (S613A), GFP-tagging/fluorescence microscopy, MVB sorting assays","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct in vitro phosphorylation assay with mutagenesis and functional downstream readout, single lab but multiple orthogonal methods","pmids":["22918958"],"is_preprint":false},{"year":2012,"finding":"HRS (HGS) is required for transport of LDL-derived cholesterol from endosomes to the endoplasmic reticulum. This function is distinct from its role in lysosomal receptor degradation: knockdown of other ESCRT proteins does not cause prominent endosomal cholesterol accumulation, and NPC1/NPC2 localization and biochemical properties are unchanged upon HRS knockdown.","method":"siRNA knockdown, filipin staining (cholesterol), fractionation, fluorescence microscopy","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — specific knockdown with defined cholesterol transport phenotype, epistasis to other ESCRT components, single lab","pmids":["22832105"],"is_preprint":false},{"year":2021,"finding":"PI3K complex II-generated PI3P on vacuolar membranes is required for Vps27 recruitment and ESCRT-0 complex formation during microautophagy induction after TORC1 inactivation; forced recruitment of Vps27 to vacuolar membranes rescues microautophagy defects in PI3KCII-deficient cells, establishing the PI3KCII-PI3P-Vps27 axis as critical for microautophagy.","method":"Yeast genetics (deletion mutants), fluorescence microscopy, forced membrane targeting constructs, survival assays under nutrient stress","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — epistasis established by forced-recruitment rescue experiment, single lab","pmids":["34798133"],"is_preprint":false},{"year":2015,"finding":"The teetering (tn) neurological mutation is a single nucleotide substitution in Hgs/HGS. Loss of HGS causes structural alterations at the neuromuscular junction (swellings, ultra-terminal sprouting, increased endosomes/MVBs), a reduction in spontaneous and evoked acetylcholine release, elevated ubiquitinated proteins in synaptosomes, and both hypermyelinated and dysmyelinated axons. TrkB levels were only modestly decreased in sciatic nerve, and RTK levels in CNS were unchanged.","method":"Positional cloning, electron microscopy, electrophysiology (NMJ recordings), western blot, immunofluorescence","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — positional cloning plus multiple independent readouts (electrophysiology, EM, biochemistry) in a well-characterized genetic model","pmids":["26115514"],"is_preprint":false},{"year":2015,"finding":"HGS plays a dual role in HBV biology: it suppresses HBV transcription/replication at aberrant levels, and promotes secretion of naked capsids through a ubiquitin-independent association with HBV core protein (HBc). HBc colocalizes with HGS near the cell periphery rather than at punctate endosomes. Mutant core (HBc 1-147 lacking ARD) can still secrete empty naked capsids promoted by HGS, but not empty virions.","method":"siRNA knockdown, overexpression, hydrodynamic delivery in mouse model, co-immunoprecipitation, confocal microscopy, virion/capsid quantification","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple methods (siRNA, OE, Co-IP, in vivo), single lab","pmids":["26431433"],"is_preprint":false},{"year":2021,"finding":"HRS/HGS depletion in myoblasts impairs differentiation by (1) upregulating MEK/ERK signaling, (2) downregulating Akt2 signaling, (3) activating myogenic repressors FOXO1 and GSK3β, and (4) inhibiting functional autophagy required for myogenesis. Pharmacological inhibition of MEK/ERK (U0126) or GSK3β (azakenpaullone) significantly restores differentiation in Hrs-depleted cells.","method":"siRNA/shRNA knockdown, pharmacological rescue experiments, western blot, differentiation assays in C2C12 and human myoblasts","journal":"BMC biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with pharmacological rescue identifying specific pathways, single lab, multiple readouts","pmids":["34330273"],"is_preprint":false},{"year":2022,"finding":"Cardiomyocyte-specific Hgs knockout mice develop restrictive cardiomyopathy (RCM)-like phenotype. HGS deficiency impairs lysosomal homeostasis, disrupts cholesterol transport and lysosomal integrity causing lysosomal storage disorder, and leads to aberrant autophagosome accumulation and protein aggregation. Suppression of protein aggregation by doxycycline treatment attenuates cardiac fibrosis and diastolic dysfunction.","method":"Conditional gene knockout (Cre/lox), proteomic analysis, electron microscopy, doxycycline pharmacological rescue, cardiac function measurements","journal":"International journal of biological sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — tissue-specific KO with proteomic and functional rescue evidence, single lab","pmids":["34330273","35342336"],"is_preprint":false},{"year":2015,"finding":"HGS depletion selectively induces apoptosis in hepatoblastoma and colorectal cancer cells with active oncogenic β-catenin signaling (CTNNB1 mutation) but spares cells with low β-catenin activity, establishing a synthetic lethal relationship between HGS function and oncogenic CTNNB1 in two independent cancer cell contexts.","method":"Kinome-wide siRNA screen, isogenic cell line pairs with inducible shRNA against CTNNB1, apoptosis measurement by flow cytometry and immunoblotting","journal":"BMC cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genome-wide screen validated in isogenic pairs with two cancer types, single lab","pmids":["26715116"],"is_preprint":false},{"year":2015,"finding":"Smooth muscle-specific Hgs deficiency causes progressive esophageal dilation with thinning muscle layer, decreased contractile responsiveness to KCl and acetylcholine, increased inhibitory neurites, T lymphocyte infiltration, and altered expression of neurotrophin and inflammation genes, indicating that HGS in SMCs is required for normal esophageal motility.","method":"Conditional knockout (SMC-specific), organ bath contractility assays, immunohistochemistry, gene expression analysis","journal":"International journal of biological sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — tissue-specific genetic loss-of-function with defined physiological and molecular phenotypes, single lab","pmids":["26078721"],"is_preprint":false},{"year":2016,"finding":"TP53 regulates HGS expression, and HGS levels control exosome size: low HGS (in TP53-KO or TP53-mutant R273H cells) leads to smaller exosomes compared to TP53-WT cells. Functional studies demonstrate that HGS-dependent exosome formation is downstream of TP53 status.","method":"iTRAQ-2D-LC-MS/MS proteomics, HGS knockdown/overexpression, nanoparticle tracking analysis, isogenic TP53 cell lines","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — proteomic discovery validated with functional knockdown/overexpression in isogenic cells, single lab","pmids":["27312428"],"is_preprint":false},{"year":2025,"finding":"HGS interacts with the coronavirus membrane (M) protein and facilitates M protein trafficking to the ER-Golgi intermediate compartment (ERGIC) for virion assembly. HGS deficiency causes M protein retention in the ER and blocks virion assembly. M-derived peptides and the drug riboflavin tetrabutyrate (RTB) bind HGS and disrupt HGS-M protein interaction, blocking coronavirus assembly.","method":"Genome-wide CRISPRi screen, co-immunoprecipitation, subcellular fractionation/immunofluorescence, in vitro and in vivo antiviral assays, peptide design and drug screening","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — CRISPRi screen validated with Co-IP, localization, pharmacological disruption, and in vivo rescue; multiple orthogonal methods","pmids":["41401029"],"is_preprint":false},{"year":2025,"finding":"Coronavirus infection induces HGS to form enlarged vesicular compartments (distinct from normal endosomes) that serve as sites of virion assembly at later infection stages. Viral structural proteins colocalize with these HGS+ compartments. APEX2-EM and cryo-CLEM confirm assembled virions within HGS+ compartments. HGS deficiency abolishes these compartments and markedly reduces assembled virions. HGS+ vesicular compartments are rearranged from Golgi and endosome/lysosome by coronavirus infection.","method":"Confocal microscopy, live-cell super-resolution microscopy, APEX2-based electron microscopy, immuno-EM, cryo-CLEM, whole-cell volume EM, HGS knockdown","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple EM modalities and live imaging in a single preprint study; not yet peer reviewed","pmids":["bio_10.1101_2025.10.25.684511"],"is_preprint":true},{"year":2025,"finding":"Salmonella effector SopB directly interacts with the ubiquitin-binding domains of the ESCRT-0 subunit HGS, and promotes ESCRT-0 recruitment to the Salmonella-containing vacuole (SCV) where HGS colocalizes with SopB.","method":"Virotrap mass spectrometry, co-immunoprecipitation with ubiquitin-binding domain constructs, immunofluorescence colocalization","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single preprint, interaction demonstrated but pathway placement is proposed rather than fully established","pmids":["bio_10.1101_2025.08.19.669813"],"is_preprint":true},{"year":2007,"finding":"Sst4p (fission yeast Vps27/HGS ortholog) localizes adjacent to forespore membranes during sporulation in a FYVE domain- and PI3-kinase-dependent manner, interacts with Hse1p, and is required for proper spore formation. UIM mutations in the Sst4p/Hse1p complex cause abnormal spore morphology.","method":"Fluorescence microscopy of GFP fusions, yeast two-hybrid/co-immunoprecipitation, deletion and UIM mutant analysis, spore viability assays","journal":"Eukaryotic cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization with functional consequence, domain mutants, single lab","pmids":["17951524"],"is_preprint":false},{"year":2025,"finding":"HGS overexpression induces epithelial-mesenchymal transition (EMT) and anchorage-independent growth in MDCK and cancer cells, while overexpression of the HGS coiled-coil domain suppresses HGF-induced EMT and anchorage-independent growth. An oligopeptide from the coiled-coil domain (OP12-462) suppresses tumor growth in vivo.","method":"Overexpression in MDCK/B16/COLO205 cells, soft agar colony formation assay, mouse xenograft tumor growth assay","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — functional OE/domain dissection with in vivo tumor growth readout, single lab","pmids":["39859488"],"is_preprint":false},{"year":2024,"finding":"Sit4 (yeast PP2A-like phosphatase) genetically interacts with Vps27 in a negative manner: sit4Δvps27Δ double mutants have shortened lifespan compared to single mutants. Vps27 is critical for iron homeostasis and mitochondrial function in sit4Δ cells, as double mutants show high iron levels and impaired mitochondrial respiration.","method":"Yeast genetics (double mutant analysis), proteomic analysis of vacuolar fractions, mitochondrial respiration assays, chronological lifespan measurement","journal":"Cells","confidence":"Low","confidence_rationale":"Tier 3 / Weak — genetic interaction established, but mechanistic link to iron/mitochondria is correlative, single lab","pmids":["38667270"],"is_preprint":false},{"year":2003,"finding":"SARA and HGS (Hgs) attenuate TGF-β1 susceptibility in human CD4+ T cells: both molecules are down-regulated in antigen-stimulated T cells, and overexpression of SARA or HGS dose-dependently decreases TGF-β1-responsive reporter gene expression, demonstrating an inhibitory function on TGF-β1 signaling in T cells.","method":"mRNA quantification, reporter gene assay, overexpression experiments in primary T cells","journal":"FASEB journal","confidence":"Low","confidence_rationale":"Tier 3 / Weak — reporter assay in T cells, no direct biochemical mechanism established beyond reduced reporter output, single lab","pmids":["12554698"],"is_preprint":false}],"current_model":"HGS (mammalian Vps27/Hrs) is an ESCRT-0 component that anchors to early endosomal membranes via its FYVE domain binding to PI3P, recruits ESCRT-I through PSDP/PTVP motifs in its C-terminus, and uses tandem UIMs to capture ubiquitinated transmembrane cargo for sorting into multivesicular bodies (MVBs); beyond its canonical endosomal sorting role, HGS acts as a scaffold for TGF-β/BMP/activin signaling by localizing Smad2, Smad5, and TAK1 to early endosomes, regulates endosomal cholesterol trafficking, promotes exosome biogenesis downstream of TP53, maintains neuromuscular junction structure and synaptic transmission, supports myogenesis and cardiac proteostasis, and interacts with the coronavirus M protein to facilitate virion assembly at HGS+ vesicular compartments."},"narrative":{"mechanistic_narrative":"HGS (mammalian Vps27/Hrs) is the core ESCRT-0 component that initiates sorting of ubiquitinated transmembrane cargo into multivesicular bodies (MVBs) at the early/prevacuolar endosome [PMID:12900393, PMID:7593183]. It achieves compartmental specificity through a FYVE domain that binds phosphatidylinositol 3-phosphate (PI3P), couples this to ubiquitin recognition via tandem UIMs that each fold as autonomous helices engaging the Ile44 hydrophobic patch of ubiquitin, and recruits downstream ESCRT-I through PSDP/PTVP C-terminal motifs that contact Vps23 [PMID:12900393, PMID:12970172, PMID:14581452]. HGS partners with Hse1 to form a barbell-like scaffold built from intertwined GAT domains and an antiparallel coiled coil that juxtaposes the cargo-, ubiquitin-, and deubiquitinase-binding surfaces for cooperative recognition of ubiquitinated membrane proteins [PMID:14581452, PMID:17543868]. PI3P-dependent recruitment and PDK1-family (Pkh1/Pkh2) phosphorylation at a conserved serine gate the membrane recruitment of HGS and downstream ESCRT-I assembly, linking HGS function to both MVB sorting and microautophagy [PMID:22918958, PMID:34798133]. Beyond cargo degradation, HGS scaffolds TGF-β/activin and BMP signaling by recruiting Smad2 and Smad5 and by localizing TAK1 to early endosomes for activation, with a C-terminal-deletion knock-in being embryonic lethal [PMID:11094085, PMID:21953618, PMID:16516194]. HGS also directs endosome-to-ER cholesterol transport independently of other ESCRT subunits, controls exosome size downstream of TP53, and is required for myoblast differentiation and cardiac proteostasis through autophagy and lysosomal homeostasis [PMID:22832105, PMID:27312428, PMID:34330273, PMID:35342336]. A point mutation in mouse Hgs (teetering) disrupts neuromuscular junction structure and synaptic transmission, establishing an in vivo neuronal requirement [PMID:26115514]. HGS is exploited during infection: it traffics the coronavirus M protein to the ERGIC and forms enlarged HGS+ compartments that serve as virion assembly sites, and a small molecule disrupting the HGS–M interaction blocks assembly [PMID:41401029].","teleology":[{"year":1995,"claim":"Established that the HGS ortholog Vps27 is a functional gatekeeper of the prevacuolar/endosomal compartment used by both biosynthetic and endocytic traffic, defining the cellular compartment at which HGS acts.","evidence":"temperature-sensitive VPS27 allele with trafficking and restoration assays in yeast","pmids":["7593183"],"confidence":"High","gaps":["Did not define the molecular interactions through which Vps27 acts","Mammalian relevance not yet established"]},{"year":2000,"claim":"Showed HGS is not solely an endosomal sorting factor but a signaling scaffold that recruits Smad2 to TGF-β/activin receptors, with in vivo essentiality demonstrated by an embryonic-lethal knock-in.","evidence":"Co-IP, knock-in mouse genetics, and reporter assays","pmids":["11094085"],"confidence":"High","gaps":["Spatial coupling of Smad recruitment to endosomes not yet shown","Whether scaffolding and ESCRT functions are separable unresolved"]},{"year":2001,"claim":"Extended HGS scaffolding to stress/MAPK signaling by linking it to TAK1 and Pak1 and to IL-2-induced c-fos promoter activation.","evidence":"Co-IP and SRE/CRE reporter assays with dominant-negative constructs","pmids":["11397816"],"confidence":"Medium","gaps":["Single lab, no structural mapping of interactions","Endosomal dependence of TAK1/Pak1 activation not tested here"]},{"year":2002,"claim":"Defined the molecular basis of HGS membrane targeting (FYVE/PI3P) and revealed a UIM-dependent autoregulatory loop in which HGS recruits Nedd4 to self-ubiquitylate and limit receptor degradation.","evidence":"Co-IP, domain deletion, dominant-negative overexpression, endosome fractionation","pmids":["12230472"],"confidence":"Medium","gaps":["Single lab","Stoichiometry and physiological scope of self-ubiquitylation unresolved"]},{"year":2003,"claim":"Resolved the atomic logic of cargo capture: tandem UIMs independently bind ubiquitin, the C-terminal PTVP/PSDP motifs directly recruit ESCRT-I, and Vps27 forms a ubiquitin-sorting receptor with Hse1, with FYVE-PI3P providing compartmental specificity.","evidence":"NMR structures, mutagenesis, lipid-binding and MVB sorting assays in yeast","pmids":["12900393","12970172","14581452"],"confidence":"High","gaps":["Higher-order architecture of the assembled receptor not yet resolved","Quantitative cargo handoff kinetics to ESCRT-I not defined"]},{"year":2003,"claim":"Showed HGS acts as an inhibitor of TGF-β1 signaling in primary T cells, indicating context-dependent signaling outcomes.","evidence":"mRNA quantification, reporter assays, overexpression in primary CD4+ T cells","pmids":["12554698"],"confidence":"Low","gaps":["No direct biochemical mechanism beyond reduced reporter output","Single lab, not independently confirmed"]},{"year":2006,"claim":"Identified Smad5 as a direct HGS partner and positioned HGS as a negative regulator of BMP transcriptional responses.","evidence":"cDNA library screen, Co-IP, BMP reporter assays","pmids":["16516194"],"confidence":"Medium","gaps":["Inhibitory versus required role for BMP signaling not reconciled with later in vivo data","Single lab"]},{"year":2007,"claim":"Provided the structural scaffold model: the Vps27/Hse1 core forms intertwined GAT domains joined by a coiled coil into a barbell that positions cargo- and DUB-binding modules for cooperative recognition.","evidence":"3.0 Å crystal structure, sedimentation equilibrium, Monte Carlo simulations","pmids":["17543868"],"confidence":"High","gaps":["Membrane-bound assembly not captured experimentally","Dynamics of cooperative ubiquitin/lipid binding inferred from simulation"]},{"year":2007,"claim":"Demonstrated conservation of HGS function in membrane biogenesis beyond MVB sorting, showing the fission yeast ortholog is required for forespore membrane formation in a FYVE/PI3K- and Hse1-dependent manner.","evidence":"GFP localization, two-hybrid/Co-IP, UIM mutants, spore viability assays","pmids":["17951524"],"confidence":"Medium","gaps":["Mammalian counterpart of sporulation role undefined","Single organism"]},{"year":2011,"claim":"Connected HGS scaffolding to developmental BMP output in vivo by showing HGS localizes TAK1 to early endosomes to enable SMAD1/5/8 and TAK1/p38 phosphorylation.","evidence":"mouse knockout, phospho-immunoblotting, TAK1 localization imaging","pmids":["21953618"],"confidence":"Medium","gaps":["Reconciliation with HGS as a BMP inhibitor not addressed","Direct kinase-scaffold contacts at endosome not structurally mapped"]},{"year":2012,"claim":"Separated HGS's cholesterol-transport role from its degradative role, showing HGS specifically routes LDL-derived cholesterol from endosomes to the ER.","evidence":"siRNA knockdown, filipin staining, fractionation in mammalian cells","pmids":["22832105"],"confidence":"Medium","gaps":["Molecular machinery linking HGS to ER cholesterol delivery unknown","Single lab"]},{"year":2012,"claim":"Established phospho-regulation and a PI3P-dependent recruitment axis for HGS recruitment and ESCRT-I assembly, extending its role to microautophagy.","evidence":"in vitro kinase assays, S613A mutant, forced-membrane-targeting rescue in yeast","pmids":["22918958","34798133"],"confidence":"Medium","gaps":["Mammalian HGS phosphosite regulation not demonstrated","Direct kinase identity in mammals unknown"]},{"year":2015,"claim":"Demonstrated an in vivo neuronal requirement: a point mutation in mouse Hgs disrupts NMJ structure, synaptic transmission, and protein/myelin homeostasis.","evidence":"positional cloning, EM, NMJ electrophysiology, western blot","pmids":["26115514"],"confidence":"High","gaps":["Which HGS cargo defects drive the synaptic phenotype unresolved","Cell-autonomous versus systemic contributions not separated"]},{"year":2015,"claim":"Revealed tissue-specific physiological roles and a cancer-context dependency, showing HGS is required for esophageal smooth-muscle motility and is synthetic lethal with oncogenic CTNNB1.","evidence":"SMC-specific KO with contractility assays; kinome siRNA screen with isogenic CTNNB1 pairs","pmids":["26078721","26715116"],"confidence":"Medium","gaps":["Mechanism linking HGS loss to apoptosis in β-catenin-active cells undefined","Single labs"]},{"year":2015,"claim":"Identified a ubiquitin-independent role for HGS in viral egress, promoting HBV naked-capsid secretion while suppressing HBV replication.","evidence":"siRNA/overexpression, in vivo hydrodynamic delivery, Co-IP, confocal microscopy","pmids":["26431433"],"confidence":"Medium","gaps":["Molecular basis of the ubiquitin-independent HBc association unclear","Single lab"]},{"year":2016,"claim":"Linked HGS expression to exosome biogenesis under TP53 control, showing HGS levels set exosome size downstream of TP53 status.","evidence":"iTRAQ proteomics, HGS knockdown/overexpression, nanoparticle tracking in isogenic TP53 cells","pmids":["27312428"],"confidence":"Medium","gaps":["Direct transcriptional regulation of HGS by TP53 not shown","Functional consequence of altered exosome size undefined"]},{"year":2021,"claim":"Connected HGS to muscle differentiation and proteostasis, showing HGS depletion blocks myogenesis via MEK/ERK, Akt2, FOXO1/GSK3β dysregulation and impaired autophagy, with pathway inhibitors rescuing differentiation.","evidence":"knockdown with pharmacological rescue in C2C12 and human myoblasts","pmids":["34330273"],"confidence":"Medium","gaps":["How loss of endosomal sorting feeds into these signaling changes unclear","Single lab"]},{"year":2022,"claim":"Demonstrated that cardiomyocyte HGS maintains lysosomal homeostasis and proteostasis, with loss causing a restrictive-cardiomyopathy phenotype reversible by suppressing protein aggregation.","evidence":"cardiomyocyte-specific KO, proteomics, EM, doxycycline rescue, cardiac function assays","pmids":["35342336"],"confidence":"Medium","gaps":["Causal hierarchy between cholesterol/lysosomal defects and aggregation not resolved","Single lab"]},{"year":2025,"claim":"Established HGS as a host factor co-opted for coronavirus assembly, trafficking the M protein to the ERGIC and forming enlarged HGS+ compartments as virion assembly sites, druggable by disrupting the HGS–M interaction.","evidence":"genome-wide CRISPRi screen, Co-IP, fractionation/imaging, APEX2-EM/cryo-CLEM, in vivo antiviral and drug/peptide assays (one report a preprint)","pmids":["41401029","bio_10.1101_2025.10.25.684511"],"confidence":"High","gaps":["Whether ESCRT-0 sorting activity is required for M trafficking unresolved","Origin/membrane identity of HGS+ assembly compartments only partly defined"]},{"year":2025,"claim":"Reported HGS as a target of pathogen effectors, with Salmonella SopB binding HGS ubiquitin-binding domains and recruiting ESCRT-0 to the Salmonella-containing vacuole.","evidence":"Virotrap mass spectrometry, Co-IP with UIM constructs, colocalization (preprint)","pmids":["bio_10.1101_2025.08.19.669813"],"confidence":"Low","gaps":["Single preprint; functional consequence on intracellular survival not established","Pathway placement proposed rather than demonstrated"]},{"year":null,"claim":"It remains unresolved how HGS's single biochemical core (PI3P/ubiquitin/ESCRT-I recognition) is partitioned among its many cellular outputs — MVB sorting, Smad/TAK1 signaling, cholesterol transport, exosome biogenesis, and viral assembly — and whether these reflect separable molecular activities or one shared mechanism deployed in different compartments.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No study dissects which HGS molecular surface drives each non-canonical role","Mammalian structural model of the assembled cargo receptor on membranes lacking","Mechanistic basis of context-dependent signaling (activating vs inhibitory) unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[0,6,12]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[3,4,5]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[2,6]}],"localization":[{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[1,6,11]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[10]},{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[16]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0,1]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[5,8,9]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[12,15,16]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[14,20]}],"complexes":["ESCRT-0 (HGS/Hse1-STAM)"],"partners":["STAM","SMAD2","SMAD5","TAK1","PAK1","NEDD4","TSG101"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O14964","full_name":"Hepatocyte growth factor-regulated tyrosine kinase substrate","aliases":["Hrs","Protein pp110"],"length_aa":777,"mass_kda":86.2,"function":"Involved in intracellular signal transduction mediated by cytokines and growth factors. 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UIM-1-Ubiquitin complex.","date":"2013","source":"Journal of molecular graphics & modelling","url":"https://pubmed.ncbi.nlm.nih.gov/24316938","citation_count":2,"is_preprint":false},{"pmid":"38667270","id":"PMC_38667270","title":"Sit4 Genetically Interacts with Vps27 to Regulate Mitochondrial Function and Lifespan in Saccharomyces cerevisiae.","date":"2024","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/38667270","citation_count":1,"is_preprint":false},{"pmid":"32638798","id":"PMC_32638798","title":"Effects of β-HgS on cell viability and intracellular oxidative stress in PC-12 cells.","date":"2020","source":"Metallomics : integrated biometal science","url":"https://pubmed.ncbi.nlm.nih.gov/32638798","citation_count":1,"is_preprint":false},{"pmid":"37204652","id":"PMC_37204652","title":"Development and Validation of Hindu Gratitude Scale (HGS-15): A Rnas Perspective.","date":"2023","source":"Journal of religion and health","url":"https://pubmed.ncbi.nlm.nih.gov/37204652","citation_count":1,"is_preprint":false},{"pmid":"39859488","id":"PMC_39859488","title":"HGS Promotes Tumor Growth, Whereas the Coiled-Coil Domain and Its Oligopeptide of HGS Suppress It.","date":"2025","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/39859488","citation_count":1,"is_preprint":false},{"pmid":"40303971","id":"PMC_40303971","title":"Thermal Decomposition of Metacinnabar (β-HgS) during Monoethylene Glycol Regeneration in Natural Gas Processing.","date":"2025","source":"Energy & fuels : an American Chemical Society journal","url":"https://pubmed.ncbi.nlm.nih.gov/40303971","citation_count":1,"is_preprint":false},{"pmid":"42235392","id":"PMC_42235392","title":"Unveiling HgS nanoparticle formation in Hg(II)-dissolved organic matter systems at low nanomolar to submicromolar levels: A comprehensive characterization via combined liquid chromatography-ICP-MS and single particle 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Cohorts","date":"2025-08-14","source":"bioRxiv","url":"https://doi.org/10.1101/2025.08.07.25333195","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.08.18.25333644","title":"The modified 30-second chair stand test (m-30s-CST) is more sensitive than handgrip strength in detecting muscle strength changes and predicting physical performance and mortality in hospitalized geriatric patients","date":"2025-08-21","source":"bioRxiv","url":"https://doi.org/10.1101/2025.08.18.25333644","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.07.16.665060","title":"Association of handgrip strength asymmetry and weakness with successful aging among older adults in China","date":"2025-07-25","source":"bioRxiv","url":"https://doi.org/10.1101/2025.07.16.665060","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.11.20.25340648","title":"Comparing Fourteen Consensus Biomarkers of Aging: Epigenetic Pace of Aging as the Strongest Predictor of Mortality in BASE-II","date":"2025-11-21","source":"bioRxiv","url":"https://doi.org/10.1101/2025.11.20.25340648","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.08.07.669084","title":"Dynamic structural changes in wheat vegetative development as an adaptive response to drought stress","date":"2025-08-07","source":"bioRxiv","url":"https://doi.org/10.1101/2025.08.07.669084","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.08.26.25334502","title":"Heart failure with physical frailty is associated with inflammation, insulin resistance, GDF-15 and impaired energy and amino acid metabolism","date":"2025-08-28","source":"bioRxiv","url":"https://doi.org/10.1101/2025.08.26.25334502","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.05.22.25328126","title":"Co-relation of Quadriceps Muscle index (QMI) with Hand Grip Strength (HGS) and Model for End Stage Liver Disease (MELD) score and cut offs for predicting sarcopenia in patients with cirrhosis: A Cross-Sectional study","date":"2025-05-27","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.22.25328126","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":42164,"output_tokens":6729,"usd":0.113713,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":15793,"output_tokens":5932,"usd":0.113632,"stage2_stop_reason":"end_turn"},"total_usd":0.227345,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"Vps27 (HGS ortholog) recruits ESCRT-I to endosomal membranes through direct binding via a PTVP-containing motif in its C-terminus; FYVE domain-mediated binding to phosphatidylinositol 3-phosphate provides compartmental specificity for the MVB sorting reaction, and both interactions are required for ubiquitinated cargo sorting into MVBs.\",\n      \"method\": \"Yeast genetics, in vivo binding assays, mutational analysis of PTVP motif, lipid-binding assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (genetic, biochemical, mutational), replicated across labs in yeast and mammalian systems\",\n      \"pmids\": [\"12900393\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Vps27 controls membrane trafficking through the prevacuolar/endosomal compartment: rapid inactivation of Vps27p causes Golgi recycling proteins (Vps10p) and endocytosed proteins (Ste3p) to accumulate in a class E compartment, and restoration of Vps27p function allows transit to resume, establishing the prevacuolar compartment as a functional intermediate for both biosynthetic and endocytic pathways.\",\n      \"method\": \"Temperature-sensitive allele of VPS27, fluorescence microscopy, protein trafficking assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional loss-of-function with defined molecular phenotypes, multiple cargo proteins tested, replicated by restoration-of-function experiment\",\n      \"pmids\": [\"7593183\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The individual UIMs of Vps27 fold as autonomous alpha-helices that each independently bind ubiquitin via the Leu8-Ile44-Val70 hydrophobic patch; both UIMs are required for efficient ubiquitin interactions and MVB cargo sorting. The binding surface is conserved with other ubiquitin-binding endocytic proteins (S5a, CUE, UBA domains).\",\n      \"method\": \"NMR solution structure, mutagenesis, in vitro binding assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — NMR structure with mutagenesis validation, defines atomic-level interaction surface\",\n      \"pmids\": [\"12970172\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Vps27 forms a complex with Hse1; together they act as a ubiquitin-sorting receptor at endosomes. Vps27 binds Vps23 (ESCRT-I) directly via two PSDP motifs in its C-terminus. Disruption of Vps27-Hse1 interaction causes severe MVB sorting defects, while loss of Vps27-Vps23 interaction reduces sorting efficiency without abolishing MVB formation. Both the Vps27 and Vps23 ubiquitin-binding surfaces contact the same cargo ubiquitin.\",\n      \"method\": \"NMR spectroscopy, mutagenesis, yeast genetics, MVB sorting assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — NMR mapping combined with genetic epistasis and functional sorting assays, multiple complementary approaches\",\n      \"pmids\": [\"14581452\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Crystal structure of the Vps27/Hse1 complex core at 3.0 Å resolution reveals two intertwined GAT domains (each formed by two helices from one subunit and one from the other) connected by an antiparallel coiled coil forming a 90 Å barbell-like scaffold. This architecture positions domains that recruit ubiquitinated cargo and deubiquitinating enzymes in proximity; Monte Carlo simulations show cooperative binding to lipids and ubiquitinated membrane proteins.\",\n      \"method\": \"X-ray crystallography (3.0 Å), sedimentation equilibrium, coarse-grained Monte Carlo simulations\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with functional domain placement, single study but rigorous structural method\",\n      \"pmids\": [\"17543868\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"HGS (Hgs) binds Smad2 via its C-terminal half and cooperates with SARA to stimulate activin receptor-mediated signaling by efficiently recruiting Smad2 to the TGF-β/activin receptor complex. A C-terminal deletion knock-in mouse is embryonic lethal (E8.5–10.5) and mutant cells show significantly decreased responses to activin and TGF-β stimulation.\",\n      \"method\": \"Co-immunoprecipitation, gene targeting (knock-in), reporter assays, cell stimulation assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding assays combined with in vivo genetic loss-of-function showing defined signaling phenotype\",\n      \"pmids\": [\"11094085\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"HGS localizes to early endosomes via its FYVE/lipid-binding domain, which is necessary for constitutive EGFR endocytosis. The ubiquitin-interacting motif (UIM) of HGS has dual function: it binds ubiquitylated proteins AND recruits Nedd4 ubiquitin ligase to promote self-ubiquitylation of HGS, thereby negatively regulating receptor degradation.\",\n      \"method\": \"Co-immunoprecipitation, dominant-negative overexpression, immunofluorescence/endosome fractionation, domain deletion analysis\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple functional domains tested with defined phenotypes, single lab, two orthogonal approaches (binding and functional assays)\",\n      \"pmids\": [\"12230472\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"HGS physically associates with TAK1 (TGF-β-activated kinase 1) and Pak1 (p21-activated kinase 1), and is required for IL-2-induced activation of the serum-response element and CRE of the c-fos promoter through the TAK1-JNK and Pak1-SRF pathways.\",\n      \"method\": \"Co-immunoprecipitation, reporter gene assays (SRE, CRE of c-fos), dominant-negative constructs\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — physical interaction confirmed by Co-IP with functional reporter assays, single lab\",\n      \"pmids\": [\"11397816\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"HGS is required for phosphorylation of SMAD1/5/8 and TAK1/p38 to transduce BMP signaling during early mouse embryo development. HGS functions to localize TAK1 to the early endosome for its activation; Hgs-mutant embryos show highly down-regulated BMP target genes.\",\n      \"method\": \"Mouse knockout genetics, western blot (phospho-SMAD1/5/8, phospho-TAK1/p38), immunofluorescence localization of TAK1\",\n      \"journal\": \"Developmental dynamics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo genetic loss-of-function with biochemical endpoint, single lab\",\n      \"pmids\": [\"21953618\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"HGS (Hgs) directly interacts with Smad5 (identified via cDNA library screen and confirmed by co-immunoprecipitation) and overexpression of Hgs attenuates BMP-dependent transcriptional responses, establishing HGS as an inhibitor of BMP signaling.\",\n      \"method\": \"cDNA expression library screen, co-immunoprecipitation, BMP-responsive reporter gene assay\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP and functional reporter assay, single lab, two orthogonal methods\",\n      \"pmids\": [\"16516194\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Pkh1/Pkh2 kinases (yeast orthologs of PDK1) directly phosphorylate Vps27 at serine 613 both in vivo and in vitro; this phosphorylation is required for proper ESCRT-I (Vps28) recruitment to endosomes. vps27-S613A mutant cells show impaired MVB sorting of Cps1 and Ste2, and ESCRT-I remains mainly cytoplasmic.\",\n      \"method\": \"In vitro kinase assay, site-directed mutagenesis (S613A), GFP-tagging/fluorescence microscopy, MVB sorting assays\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct in vitro phosphorylation assay with mutagenesis and functional downstream readout, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"22918958\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"HRS (HGS) is required for transport of LDL-derived cholesterol from endosomes to the endoplasmic reticulum. This function is distinct from its role in lysosomal receptor degradation: knockdown of other ESCRT proteins does not cause prominent endosomal cholesterol accumulation, and NPC1/NPC2 localization and biochemical properties are unchanged upon HRS knockdown.\",\n      \"method\": \"siRNA knockdown, filipin staining (cholesterol), fractionation, fluorescence microscopy\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — specific knockdown with defined cholesterol transport phenotype, epistasis to other ESCRT components, single lab\",\n      \"pmids\": [\"22832105\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PI3K complex II-generated PI3P on vacuolar membranes is required for Vps27 recruitment and ESCRT-0 complex formation during microautophagy induction after TORC1 inactivation; forced recruitment of Vps27 to vacuolar membranes rescues microautophagy defects in PI3KCII-deficient cells, establishing the PI3KCII-PI3P-Vps27 axis as critical for microautophagy.\",\n      \"method\": \"Yeast genetics (deletion mutants), fluorescence microscopy, forced membrane targeting constructs, survival assays under nutrient stress\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — epistasis established by forced-recruitment rescue experiment, single lab\",\n      \"pmids\": [\"34798133\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The teetering (tn) neurological mutation is a single nucleotide substitution in Hgs/HGS. Loss of HGS causes structural alterations at the neuromuscular junction (swellings, ultra-terminal sprouting, increased endosomes/MVBs), a reduction in spontaneous and evoked acetylcholine release, elevated ubiquitinated proteins in synaptosomes, and both hypermyelinated and dysmyelinated axons. TrkB levels were only modestly decreased in sciatic nerve, and RTK levels in CNS were unchanged.\",\n      \"method\": \"Positional cloning, electron microscopy, electrophysiology (NMJ recordings), western blot, immunofluorescence\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — positional cloning plus multiple independent readouts (electrophysiology, EM, biochemistry) in a well-characterized genetic model\",\n      \"pmids\": [\"26115514\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"HGS plays a dual role in HBV biology: it suppresses HBV transcription/replication at aberrant levels, and promotes secretion of naked capsids through a ubiquitin-independent association with HBV core protein (HBc). HBc colocalizes with HGS near the cell periphery rather than at punctate endosomes. Mutant core (HBc 1-147 lacking ARD) can still secrete empty naked capsids promoted by HGS, but not empty virions.\",\n      \"method\": \"siRNA knockdown, overexpression, hydrodynamic delivery in mouse model, co-immunoprecipitation, confocal microscopy, virion/capsid quantification\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple methods (siRNA, OE, Co-IP, in vivo), single lab\",\n      \"pmids\": [\"26431433\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HRS/HGS depletion in myoblasts impairs differentiation by (1) upregulating MEK/ERK signaling, (2) downregulating Akt2 signaling, (3) activating myogenic repressors FOXO1 and GSK3β, and (4) inhibiting functional autophagy required for myogenesis. Pharmacological inhibition of MEK/ERK (U0126) or GSK3β (azakenpaullone) significantly restores differentiation in Hrs-depleted cells.\",\n      \"method\": \"siRNA/shRNA knockdown, pharmacological rescue experiments, western blot, differentiation assays in C2C12 and human myoblasts\",\n      \"journal\": \"BMC biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with pharmacological rescue identifying specific pathways, single lab, multiple readouts\",\n      \"pmids\": [\"34330273\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cardiomyocyte-specific Hgs knockout mice develop restrictive cardiomyopathy (RCM)-like phenotype. HGS deficiency impairs lysosomal homeostasis, disrupts cholesterol transport and lysosomal integrity causing lysosomal storage disorder, and leads to aberrant autophagosome accumulation and protein aggregation. Suppression of protein aggregation by doxycycline treatment attenuates cardiac fibrosis and diastolic dysfunction.\",\n      \"method\": \"Conditional gene knockout (Cre/lox), proteomic analysis, electron microscopy, doxycycline pharmacological rescue, cardiac function measurements\",\n      \"journal\": \"International journal of biological sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — tissue-specific KO with proteomic and functional rescue evidence, single lab\",\n      \"pmids\": [\"34330273\", \"35342336\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"HGS depletion selectively induces apoptosis in hepatoblastoma and colorectal cancer cells with active oncogenic β-catenin signaling (CTNNB1 mutation) but spares cells with low β-catenin activity, establishing a synthetic lethal relationship between HGS function and oncogenic CTNNB1 in two independent cancer cell contexts.\",\n      \"method\": \"Kinome-wide siRNA screen, isogenic cell line pairs with inducible shRNA against CTNNB1, apoptosis measurement by flow cytometry and immunoblotting\",\n      \"journal\": \"BMC cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genome-wide screen validated in isogenic pairs with two cancer types, single lab\",\n      \"pmids\": [\"26715116\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Smooth muscle-specific Hgs deficiency causes progressive esophageal dilation with thinning muscle layer, decreased contractile responsiveness to KCl and acetylcholine, increased inhibitory neurites, T lymphocyte infiltration, and altered expression of neurotrophin and inflammation genes, indicating that HGS in SMCs is required for normal esophageal motility.\",\n      \"method\": \"Conditional knockout (SMC-specific), organ bath contractility assays, immunohistochemistry, gene expression analysis\",\n      \"journal\": \"International journal of biological sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — tissue-specific genetic loss-of-function with defined physiological and molecular phenotypes, single lab\",\n      \"pmids\": [\"26078721\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"TP53 regulates HGS expression, and HGS levels control exosome size: low HGS (in TP53-KO or TP53-mutant R273H cells) leads to smaller exosomes compared to TP53-WT cells. Functional studies demonstrate that HGS-dependent exosome formation is downstream of TP53 status.\",\n      \"method\": \"iTRAQ-2D-LC-MS/MS proteomics, HGS knockdown/overexpression, nanoparticle tracking analysis, isogenic TP53 cell lines\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — proteomic discovery validated with functional knockdown/overexpression in isogenic cells, single lab\",\n      \"pmids\": [\"27312428\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HGS interacts with the coronavirus membrane (M) protein and facilitates M protein trafficking to the ER-Golgi intermediate compartment (ERGIC) for virion assembly. HGS deficiency causes M protein retention in the ER and blocks virion assembly. M-derived peptides and the drug riboflavin tetrabutyrate (RTB) bind HGS and disrupt HGS-M protein interaction, blocking coronavirus assembly.\",\n      \"method\": \"Genome-wide CRISPRi screen, co-immunoprecipitation, subcellular fractionation/immunofluorescence, in vitro and in vivo antiviral assays, peptide design and drug screening\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — CRISPRi screen validated with Co-IP, localization, pharmacological disruption, and in vivo rescue; multiple orthogonal methods\",\n      \"pmids\": [\"41401029\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Coronavirus infection induces HGS to form enlarged vesicular compartments (distinct from normal endosomes) that serve as sites of virion assembly at later infection stages. Viral structural proteins colocalize with these HGS+ compartments. APEX2-EM and cryo-CLEM confirm assembled virions within HGS+ compartments. HGS deficiency abolishes these compartments and markedly reduces assembled virions. HGS+ vesicular compartments are rearranged from Golgi and endosome/lysosome by coronavirus infection.\",\n      \"method\": \"Confocal microscopy, live-cell super-resolution microscopy, APEX2-based electron microscopy, immuno-EM, cryo-CLEM, whole-cell volume EM, HGS knockdown\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple EM modalities and live imaging in a single preprint study; not yet peer reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.10.25.684511\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Salmonella effector SopB directly interacts with the ubiquitin-binding domains of the ESCRT-0 subunit HGS, and promotes ESCRT-0 recruitment to the Salmonella-containing vacuole (SCV) where HGS colocalizes with SopB.\",\n      \"method\": \"Virotrap mass spectrometry, co-immunoprecipitation with ubiquitin-binding domain constructs, immunofluorescence colocalization\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single preprint, interaction demonstrated but pathway placement is proposed rather than fully established\",\n      \"pmids\": [\"bio_10.1101_2025.08.19.669813\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Sst4p (fission yeast Vps27/HGS ortholog) localizes adjacent to forespore membranes during sporulation in a FYVE domain- and PI3-kinase-dependent manner, interacts with Hse1p, and is required for proper spore formation. UIM mutations in the Sst4p/Hse1p complex cause abnormal spore morphology.\",\n      \"method\": \"Fluorescence microscopy of GFP fusions, yeast two-hybrid/co-immunoprecipitation, deletion and UIM mutant analysis, spore viability assays\",\n      \"journal\": \"Eukaryotic cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization with functional consequence, domain mutants, single lab\",\n      \"pmids\": [\"17951524\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HGS overexpression induces epithelial-mesenchymal transition (EMT) and anchorage-independent growth in MDCK and cancer cells, while overexpression of the HGS coiled-coil domain suppresses HGF-induced EMT and anchorage-independent growth. An oligopeptide from the coiled-coil domain (OP12-462) suppresses tumor growth in vivo.\",\n      \"method\": \"Overexpression in MDCK/B16/COLO205 cells, soft agar colony formation assay, mouse xenograft tumor growth assay\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — functional OE/domain dissection with in vivo tumor growth readout, single lab\",\n      \"pmids\": [\"39859488\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Sit4 (yeast PP2A-like phosphatase) genetically interacts with Vps27 in a negative manner: sit4Δvps27Δ double mutants have shortened lifespan compared to single mutants. Vps27 is critical for iron homeostasis and mitochondrial function in sit4Δ cells, as double mutants show high iron levels and impaired mitochondrial respiration.\",\n      \"method\": \"Yeast genetics (double mutant analysis), proteomic analysis of vacuolar fractions, mitochondrial respiration assays, chronological lifespan measurement\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — genetic interaction established, but mechanistic link to iron/mitochondria is correlative, single lab\",\n      \"pmids\": [\"38667270\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"SARA and HGS (Hgs) attenuate TGF-β1 susceptibility in human CD4+ T cells: both molecules are down-regulated in antigen-stimulated T cells, and overexpression of SARA or HGS dose-dependently decreases TGF-β1-responsive reporter gene expression, demonstrating an inhibitory function on TGF-β1 signaling in T cells.\",\n      \"method\": \"mRNA quantification, reporter gene assay, overexpression experiments in primary T cells\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — reporter assay in T cells, no direct biochemical mechanism established beyond reduced reporter output, single lab\",\n      \"pmids\": [\"12554698\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"HGS (mammalian Vps27/Hrs) is an ESCRT-0 component that anchors to early endosomal membranes via its FYVE domain binding to PI3P, recruits ESCRT-I through PSDP/PTVP motifs in its C-terminus, and uses tandem UIMs to capture ubiquitinated transmembrane cargo for sorting into multivesicular bodies (MVBs); beyond its canonical endosomal sorting role, HGS acts as a scaffold for TGF-β/BMP/activin signaling by localizing Smad2, Smad5, and TAK1 to early endosomes, regulates endosomal cholesterol trafficking, promotes exosome biogenesis downstream of TP53, maintains neuromuscular junction structure and synaptic transmission, supports myogenesis and cardiac proteostasis, and interacts with the coronavirus M protein to facilitate virion assembly at HGS+ vesicular compartments.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"HGS (mammalian Vps27/Hrs) is the core ESCRT-0 component that initiates sorting of ubiquitinated transmembrane cargo into multivesicular bodies (MVBs) at the early/prevacuolar endosome [#0, #1]. It achieves compartmental specificity through a FYVE domain that binds phosphatidylinositol 3-phosphate (PI3P), couples this to ubiquitin recognition via tandem UIMs that each fold as autonomous helices engaging the Ile44 hydrophobic patch of ubiquitin, and recruits downstream ESCRT-I through PSDP/PTVP C-terminal motifs that contact Vps23 [#0, #2, #3]. HGS partners with Hse1 to form a barbell-like scaffold built from intertwined GAT domains and an antiparallel coiled coil that juxtaposes the cargo-, ubiquitin-, and deubiquitinase-binding surfaces for cooperative recognition of ubiquitinated membrane proteins [#3, #4]. PI3P-dependent recruitment and PDK1-family (Pkh1/Pkh2) phosphorylation at a conserved serine gate the membrane recruitment of HGS and downstream ESCRT-I assembly, linking HGS function to both MVB sorting and microautophagy [#10, #12]. Beyond cargo degradation, HGS scaffolds TGF-\\u03b2/activin and BMP signaling by recruiting Smad2 and Smad5 and by localizing TAK1 to early endosomes for activation, with a C-terminal-deletion knock-in being embryonic lethal [#5, #8, #9]. HGS also directs endosome-to-ER cholesterol transport independently of other ESCRT subunits, controls exosome size downstream of TP53, and is required for myoblast differentiation and cardiac proteostasis through autophagy and lysosomal homeostasis [#11, #19, #15, #16]. A point mutation in mouse Hgs (teetering) disrupts neuromuscular junction structure and synaptic transmission, establishing an in vivo neuronal requirement [#13]. HGS is exploited during infection: it traffics the coronavirus M protein to the ERGIC and forms enlarged HGS+ compartments that serve as virion assembly sites, and a small molecule disrupting the HGS\\u2013M interaction blocks assembly [#20].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Established that the HGS ortholog Vps27 is a functional gatekeeper of the prevacuolar/endosomal compartment used by both biosynthetic and endocytic traffic, defining the cellular compartment at which HGS acts.\",\n      \"evidence\": \"temperature-sensitive VPS27 allele with trafficking and restoration assays in yeast\",\n      \"pmids\": [\"7593183\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the molecular interactions through which Vps27 acts\", \"Mammalian relevance not yet established\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Showed HGS is not solely an endosomal sorting factor but a signaling scaffold that recruits Smad2 to TGF-\\u03b2/activin receptors, with in vivo essentiality demonstrated by an embryonic-lethal knock-in.\",\n      \"evidence\": \"Co-IP, knock-in mouse genetics, and reporter assays\",\n      \"pmids\": [\"11094085\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Spatial coupling of Smad recruitment to endosomes not yet shown\", \"Whether scaffolding and ESCRT functions are separable unresolved\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Extended HGS scaffolding to stress/MAPK signaling by linking it to TAK1 and Pak1 and to IL-2-induced c-fos promoter activation.\",\n      \"evidence\": \"Co-IP and SRE/CRE reporter assays with dominant-negative constructs\",\n      \"pmids\": [\"11397816\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, no structural mapping of interactions\", \"Endosomal dependence of TAK1/Pak1 activation not tested here\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Defined the molecular basis of HGS membrane targeting (FYVE/PI3P) and revealed a UIM-dependent autoregulatory loop in which HGS recruits Nedd4 to self-ubiquitylate and limit receptor degradation.\",\n      \"evidence\": \"Co-IP, domain deletion, dominant-negative overexpression, endosome fractionation\",\n      \"pmids\": [\"12230472\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Stoichiometry and physiological scope of self-ubiquitylation unresolved\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Resolved the atomic logic of cargo capture: tandem UIMs independently bind ubiquitin, the C-terminal PTVP/PSDP motifs directly recruit ESCRT-I, and Vps27 forms a ubiquitin-sorting receptor with Hse1, with FYVE-PI3P providing compartmental specificity.\",\n      \"evidence\": \"NMR structures, mutagenesis, lipid-binding and MVB sorting assays in yeast\",\n      \"pmids\": [\"12900393\", \"12970172\", \"14581452\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Higher-order architecture of the assembled receptor not yet resolved\", \"Quantitative cargo handoff kinetics to ESCRT-I not defined\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Showed HGS acts as an inhibitor of TGF-\\u03b21 signaling in primary T cells, indicating context-dependent signaling outcomes.\",\n      \"evidence\": \"mRNA quantification, reporter assays, overexpression in primary CD4+ T cells\",\n      \"pmids\": [\"12554698\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No direct biochemical mechanism beyond reduced reporter output\", \"Single lab, not independently confirmed\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identified Smad5 as a direct HGS partner and positioned HGS as a negative regulator of BMP transcriptional responses.\",\n      \"evidence\": \"cDNA library screen, Co-IP, BMP reporter assays\",\n      \"pmids\": [\"16516194\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Inhibitory versus required role for BMP signaling not reconciled with later in vivo data\", \"Single lab\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Provided the structural scaffold model: the Vps27/Hse1 core forms intertwined GAT domains joined by a coiled coil into a barbell that positions cargo- and DUB-binding modules for cooperative recognition.\",\n      \"evidence\": \"3.0 \\u00c5 crystal structure, sedimentation equilibrium, Monte Carlo simulations\",\n      \"pmids\": [\"17543868\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Membrane-bound assembly not captured experimentally\", \"Dynamics of cooperative ubiquitin/lipid binding inferred from simulation\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstrated conservation of HGS function in membrane biogenesis beyond MVB sorting, showing the fission yeast ortholog is required for forespore membrane formation in a FYVE/PI3K- and Hse1-dependent manner.\",\n      \"evidence\": \"GFP localization, two-hybrid/Co-IP, UIM mutants, spore viability assays\",\n      \"pmids\": [\"17951524\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mammalian counterpart of sporulation role undefined\", \"Single organism\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Connected HGS scaffolding to developmental BMP output in vivo by showing HGS localizes TAK1 to early endosomes to enable SMAD1/5/8 and TAK1/p38 phosphorylation.\",\n      \"evidence\": \"mouse knockout, phospho-immunoblotting, TAK1 localization imaging\",\n      \"pmids\": [\"21953618\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Reconciliation with HGS as a BMP inhibitor not addressed\", \"Direct kinase-scaffold contacts at endosome not structurally mapped\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Separated HGS's cholesterol-transport role from its degradative role, showing HGS specifically routes LDL-derived cholesterol from endosomes to the ER.\",\n      \"evidence\": \"siRNA knockdown, filipin staining, fractionation in mammalian cells\",\n      \"pmids\": [\"22832105\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular machinery linking HGS to ER cholesterol delivery unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Established phospho-regulation and a PI3P-dependent recruitment axis for HGS recruitment and ESCRT-I assembly, extending its role to microautophagy.\",\n      \"evidence\": \"in vitro kinase assays, S613A mutant, forced-membrane-targeting rescue in yeast\",\n      \"pmids\": [\"22918958\", \"34798133\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mammalian HGS phosphosite regulation not demonstrated\", \"Direct kinase identity in mammals unknown\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Demonstrated an in vivo neuronal requirement: a point mutation in mouse Hgs disrupts NMJ structure, synaptic transmission, and protein/myelin homeostasis.\",\n      \"evidence\": \"positional cloning, EM, NMJ electrophysiology, western blot\",\n      \"pmids\": [\"26115514\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which HGS cargo defects drive the synaptic phenotype unresolved\", \"Cell-autonomous versus systemic contributions not separated\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Revealed tissue-specific physiological roles and a cancer-context dependency, showing HGS is required for esophageal smooth-muscle motility and is synthetic lethal with oncogenic CTNNB1.\",\n      \"evidence\": \"SMC-specific KO with contractility assays; kinome siRNA screen with isogenic CTNNB1 pairs\",\n      \"pmids\": [\"26078721\", \"26715116\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking HGS loss to apoptosis in \\u03b2-catenin-active cells undefined\", \"Single labs\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identified a ubiquitin-independent role for HGS in viral egress, promoting HBV naked-capsid secretion while suppressing HBV replication.\",\n      \"evidence\": \"siRNA/overexpression, in vivo hydrodynamic delivery, Co-IP, confocal microscopy\",\n      \"pmids\": [\"26431433\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of the ubiquitin-independent HBc association unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Linked HGS expression to exosome biogenesis under TP53 control, showing HGS levels set exosome size downstream of TP53 status.\",\n      \"evidence\": \"iTRAQ proteomics, HGS knockdown/overexpression, nanoparticle tracking in isogenic TP53 cells\",\n      \"pmids\": [\"27312428\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct transcriptional regulation of HGS by TP53 not shown\", \"Functional consequence of altered exosome size undefined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Connected HGS to muscle differentiation and proteostasis, showing HGS depletion blocks myogenesis via MEK/ERK, Akt2, FOXO1/GSK3\\u03b2 dysregulation and impaired autophagy, with pathway inhibitors rescuing differentiation.\",\n      \"evidence\": \"knockdown with pharmacological rescue in C2C12 and human myoblasts\",\n      \"pmids\": [\"34330273\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How loss of endosomal sorting feeds into these signaling changes unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrated that cardiomyocyte HGS maintains lysosomal homeostasis and proteostasis, with loss causing a restrictive-cardiomyopathy phenotype reversible by suppressing protein aggregation.\",\n      \"evidence\": \"cardiomyocyte-specific KO, proteomics, EM, doxycycline rescue, cardiac function assays\",\n      \"pmids\": [\"35342336\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal hierarchy between cholesterol/lysosomal defects and aggregation not resolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Established HGS as a host factor co-opted for coronavirus assembly, trafficking the M protein to the ERGIC and forming enlarged HGS+ compartments as virion assembly sites, druggable by disrupting the HGS\\u2013M interaction.\",\n      \"evidence\": \"genome-wide CRISPRi screen, Co-IP, fractionation/imaging, APEX2-EM/cryo-CLEM, in vivo antiviral and drug/peptide assays (one report a preprint)\",\n      \"pmids\": [\"41401029\", \"bio_10.1101_2025.10.25.684511\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether ESCRT-0 sorting activity is required for M trafficking unresolved\", \"Origin/membrane identity of HGS+ assembly compartments only partly defined\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Reported HGS as a target of pathogen effectors, with Salmonella SopB binding HGS ubiquitin-binding domains and recruiting ESCRT-0 to the Salmonella-containing vacuole.\",\n      \"evidence\": \"Virotrap mass spectrometry, Co-IP with UIM constructs, colocalization (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.08.19.669813\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single preprint; functional consequence on intracellular survival not established\", \"Pathway placement proposed rather than demonstrated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how HGS's single biochemical core (PI3P/ubiquitin/ESCRT-I recognition) is partitioned among its many cellular outputs \\u2014 MVB sorting, Smad/TAK1 signaling, cholesterol transport, exosome biogenesis, and viral assembly \\u2014 and whether these reflect separable molecular activities or one shared mechanism deployed in different compartments.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No study dissects which HGS molecular surface drives each non-canonical role\", \"Mammalian structural model of the assembled cargo receptor on membranes lacking\", \"Mechanistic basis of context-dependent signaling (activating vs inhibitory) unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [0, 6, 12]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [3, 4, 5]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [2, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [1, 6, 11]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [10]},\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [5, 8, 9]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [12, 15, 16]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [14, 20]}\n    ],\n    \"complexes\": [\"ESCRT-0 (HGS/Hse1-STAM)\"],\n    \"partners\": [\"STAM\", \"Smad2\", \"Smad5\", \"TAK1\", \"PAK1\", \"NEDD4\", \"TSG101\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}