{"gene":"STARD3NL","run_date":"2026-06-10T07:46:42","timeline":{"discoveries":[{"year":2002,"finding":"STARD3NL (MENTHO) is a late endosomal membrane protein synthesized as two isoforms (alpha: 234 aa, beta: 227 aa) that can be phosphorylated. It localizes to the membrane of late endosomes with its amino and carboxyl-terminal extremities projecting toward the cytoplasm. Overexpression leads to accumulation of enlarged endosomes, indicating an intrinsic biological function in endocytic transport beyond protein anchoring.","method":"cDNA cloning, subcellular fractionation/localization, overexpression with morphological readout","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — direct localization experiments with functional morphological consequence, single lab, multiple methods","pmids":["12393907"],"is_preprint":false},{"year":2005,"finding":"The MENTAL domain of STARD3NL (MENTHO) binds cholesterol in vivo, mediates homo-interaction of MENTHO, and mediates hetero-interaction between MENTHO and MLN64 (STARD3). GST pull-down and co-immunoprecipitation confirmed direct protein–protein interactions. FRET imaging with YFP/CFP fusion proteins in living cells confirmed MENTHO homo-interaction and interaction with MLN64 in late endosomal membranes.","method":"In vivo photocholesterol binding assay, GST pull-down, co-immunoprecipitation, FRET imaging with fluorescent fusion proteins","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal methods (in vivo cholesterol binding assay, GST pulldown, Co-IP, live-cell FRET) in single rigorous study","pmids":["15718238"],"is_preprint":false},{"year":2006,"finding":"STARD3NL (MENTHO) and MLN64 share the MENTAL domain (four transmembrane helices), which targets both proteins to late endosomes, mediates homo- and hetero-interactions, and binds cholesterol in vivo, defining discrete cholesterol-containing subdomains within late endosomal membranes where they may function in cholesterol transport.","method":"Review/synthesis citing prior experimental data from the same group (cholesterol binding, Co-IP, localization)","journal":"Biochemical Society transactions","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — consolidates prior experimental findings; review article but grounded in published experimental data","pmids":["16709157"],"is_preprint":false},{"year":2016,"finding":"STARD3NL, anchored on the limiting membrane of late endosomes, interacts directly with ER-anchored VAP proteins (VAP-A and VAP-B) to form ER–late endosome membrane contact sites (MCSs). These contacts affect endosome dynamics and are implicated in cholesterol transport.","method":"Protein interaction studies (implied by review citing primary data); membrane contact site characterization","journal":"Biochemical Society transactions","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — review article summarizing interaction data with VAP proteins and functional consequences on endosome dynamics; single lab","pmids":["27068960"],"is_preprint":false},{"year":2022,"finding":"STARD3NL binds directly to Annexin A2 (ANXA2) and suppresses β-catenin expression, leading to inactivation of Wnt/β-catenin signaling and inhibition of osteogenic differentiation. Inhibition of Stard3nl induced nuclear translocation of β-catenin and activated Wnt signaling. In vivo, AAV9-mediated silencing of Stard3nl reversed bone loss in OVX-induced osteoporotic mice.","method":"Co-immunoprecipitation (Stard3nl–Anxa2 binding), loss-of-function (siRNA/shRNA knockdown), β-catenin nuclear translocation assay, Wnt reporter assay, in vivo AAV9 gene silencing in OVX mouse model","journal":"Journal of cellular and molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — Co-IP for binding, functional KD with defined signaling readout, in vivo validation; single lab","pmids":["35098646"],"is_preprint":false},{"year":2026,"finding":"FBXO6 (an E3 ubiquitin ligase) interacts with STARD3NL and promotes its destabilization (ubiquitin-mediated degradation). STARD3NL knockdown attenuated the impaired osteogenesis caused by FBXO6 silencing, placing STARD3NL downstream of FBXO6 in a pathway regulating osteoblast differentiation via Wnt/β-catenin signaling.","method":"Label-free quantitative proteomics, co-immunoprecipitation (FBXO6–STARD3NL), siRNA knockdown, osteogenic differentiation assays (ALP activity, calcium nodule formation), genetic epistasis (STARD3NL KD rescues FBXO6 KD phenotype)","journal":"Biochemical pharmacology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — proteomics identification plus Co-IP and epistasis rescue experiment; single lab, single study","pmids":["41483826"],"is_preprint":false}],"current_model":"STARD3NL (MENTHO) is a late endosomal membrane protein whose MENTAL domain binds cholesterol in vivo, mediates homo- and hetero-interactions with MLN64 (STARD3), and interacts with ER-resident VAP proteins to form ER–endosome membrane contact sites involved in cholesterol transport; in the context of bone biology, STARD3NL binds Annexin A2 to suppress Wnt/β-catenin signaling and inhibit osteogenesis, and is itself destabilized by the E3 ubiquitin ligase FBXO6."},"narrative":{"mechanistic_narrative":"STARD3NL (MENTHO) is a late endosomal membrane protein that organizes cholesterol-containing subdomains of the endosomal limiting membrane and contributes to inter-organelle cholesterol transport [PMID:12393907, PMID:16709157]. It is anchored by a four-transmembrane MENTAL domain that both targets the protein to late endosomes and binds cholesterol in vivo; through this domain STARD3NL self-associates and forms hetero-interactions with the related protein MLN64/STARD3 within late endosomal membranes [PMID:15718238, PMID:16709157]. STARD3NL further bridges late endosomes to the endoplasmic reticulum by binding directly to the ER-anchored VAP proteins VAP-A and VAP-B, establishing ER–late endosome membrane contact sites that influence endosome dynamics [PMID:27068960]. Independent of its endosomal role, STARD3NL acts in bone biology as a negative regulator of osteogenesis: it binds Annexin A2 (ANXA2) and suppresses β-catenin, thereby inactivating Wnt/β-catenin signaling and inhibiting osteogenic differentiation, with loss of STARD3NL activating Wnt signaling and reversing bone loss in vivo [PMID:35098646]. STARD3NL protein levels are controlled by the E3 ubiquitin ligase FBXO6, which interacts with STARD3NL and promotes its ubiquitin-mediated degradation, placing STARD3NL downstream of FBXO6 in the control of osteoblast differentiation [PMID:41483826].","teleology":[{"year":2002,"claim":"Established STARD3NL as a bona fide late endosomal membrane protein with an intrinsic role in endocytic transport rather than a passive membrane anchor.","evidence":"cDNA cloning, subcellular fractionation/localization, and overexpression with a morphological (enlarged endosome) readout","pmids":["12393907"],"confidence":"Medium","gaps":["Molecular mechanism by which overexpression enlarges endosomes not defined","Functional consequence of the two phosphorylated isoforms unknown"]},{"year":2005,"claim":"Defined the MENTAL domain as the functional unit, showing it binds cholesterol in vivo and mediates STARD3NL homo-interaction and hetero-interaction with MLN64/STARD3 in endosomal membranes.","evidence":"In vivo photocholesterol binding, GST pull-down, co-immunoprecipitation, and live-cell FRET with fluorescent fusion proteins","pmids":["15718238"],"confidence":"High","gaps":["Stoichiometry and structural basis of cholesterol binding not resolved","Functional output of the STARD3NL–MLN64 hetero-complex not established"]},{"year":2006,"claim":"Consolidated the MENTAL domain model in which STARD3NL and MLN64 define discrete cholesterol-rich endosomal subdomains potentially functioning in cholesterol transport.","evidence":"Review synthesizing prior cholesterol-binding, Co-IP, and localization data from the same group","pmids":["16709157"],"confidence":"Medium","gaps":["Direct demonstration of cholesterol transport activity absent","No reconstitution of the proposed transport function"]},{"year":2016,"claim":"Positioned STARD3NL as a tether linking late endosomes to the ER via direct binding to VAP-A and VAP-B, forming membrane contact sites that govern endosome dynamics.","evidence":"Protein interaction and membrane contact site characterization (review citing primary data)","pmids":["27068960"],"confidence":"Medium","gaps":["FFAT-like motif mediating VAP binding not mapped in the timeline","Quantitative contribution of these contacts to cholesterol flux unmeasured"]},{"year":2022,"claim":"Revealed a distinct signaling role in bone, where STARD3NL binds Annexin A2 to suppress β-catenin and inhibit Wnt-driven osteogenesis, with in vivo relevance to osteoporosis.","evidence":"Co-IP, siRNA/shRNA knockdown, β-catenin nuclear translocation and Wnt reporter assays, and AAV9 silencing in an OVX osteoporotic mouse model","pmids":["35098646"],"confidence":"Medium","gaps":["Mechanistic link between ANXA2 binding and β-catenin suppression unresolved","Whether this signaling role depends on STARD3NL's endosomal/cholesterol functions unknown"]},{"year":2026,"claim":"Identified upstream control of STARD3NL abundance, showing FBXO6 targets it for ubiquitin-mediated degradation in a pathway regulating osteoblast differentiation.","evidence":"Label-free proteomics, FBXO6–STARD3NL Co-IP, knockdown, osteogenic differentiation assays, and epistasis rescue","pmids":["41483826"],"confidence":"Medium","gaps":["Ubiquitination site(s) on STARD3NL not mapped","Whether FBXO6 regulates the endosomal/cholesterol functions of STARD3NL untested"]},{"year":null,"claim":"How STARD3NL's endosomal cholesterol-transport function mechanistically relates to its Wnt/osteogenic signaling role, and whether the two are coupled, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model linking cholesterol/MCS function to Wnt regulation","Direct cholesterol-transport activity not biochemically demonstrated","Structural data on the MENTAL domain and its ligand/partner interfaces absent"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[1,2]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[4]}],"localization":[{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[0,1,3]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[3]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[4]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[4,5]}],"complexes":[],"partners":["STARD3","VAPA","VAPB","ANXA2","FBXO6"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O95772","full_name":"STARD3 N-terminal-like protein","aliases":["MLN64 N-terminal domain homolog"],"length_aa":234,"mass_kda":26.7,"function":"Tethering protein that creates contact site between the endoplasmic reticulum and late endosomes: localizes to late endosome membranes and contacts the endoplasmic reticulum via interaction with VAPA and VAPB (PubMed:24105263)","subcellular_location":"Late endosome membrane","url":"https://www.uniprot.org/uniprotkb/O95772/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/STARD3NL","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"TMEM106B","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/STARD3NL","total_profiled":1310},"omim":[{"mim_id":"611759","title":"STARD3 N-TERMINAL-LIKE; STARD3NL","url":"https://www.omim.org/entry/611759"},{"mim_id":"607048","title":"START DOMAIN-CONTAINING PROTEIN 3; STARD3","url":"https://www.omim.org/entry/607048"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Vesicles","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/STARD3NL"},"hgnc":{"alias_symbol":["MENTHO","MGC3251"],"prev_symbol":[]},"alphafold":{"accession":"O95772","domains":[{"cath_id":"-","chopping":"50-196","consensus_level":"high","plddt":67.879,"start":50,"end":196}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O95772","model_url":"https://alphafold.ebi.ac.uk/files/AF-O95772-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O95772-F1-predicted_aligned_error_v6.png","plddt_mean":62.16},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=STARD3NL","jax_strain_url":"https://www.jax.org/strain/search?query=STARD3NL"},"sequence":{"accession":"O95772","fasta_url":"https://rest.uniprot.org/uniprotkb/O95772.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O95772/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O95772"}},"corpus_meta":[{"pmid":"23628605","id":"PMC_23628605","title":"Steroid hormone synthesis in mitochondria.","date":"2013","source":"Molecular and cellular endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/23628605","citation_count":350,"is_preprint":false},{"pmid":"30890710","id":"PMC_30890710","title":"Genome-scale Capture C promoter interactions implicate effector genes at GWAS loci for bone mineral density.","date":"2019","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/30890710","citation_count":117,"is_preprint":false},{"pmid":"29284707","id":"PMC_29284707","title":"Structural Alterations of MET Trigger Response to MET Kinase Inhibition in Lung Adenocarcinoma Patients.","date":"2017","source":"Clinical cancer research : an official journal of the American Association for Cancer Research","url":"https://pubmed.ncbi.nlm.nih.gov/29284707","citation_count":75,"is_preprint":false},{"pmid":"15718238","id":"PMC_15718238","title":"Functional characterization of the MENTAL domain.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15718238","citation_count":55,"is_preprint":false},{"pmid":"12393907","id":"PMC_12393907","title":"MENTHO, a MLN64 homologue devoid of the START domain.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12393907","citation_count":45,"is_preprint":false},{"pmid":"16709157","id":"PMC_16709157","title":"MLN64 and MENTHO, two mediators of endosomal cholesterol transport.","date":"2006","source":"Biochemical Society transactions","url":"https://pubmed.ncbi.nlm.nih.gov/16709157","citation_count":41,"is_preprint":false},{"pmid":"31190075","id":"PMC_31190075","title":"Sepsis in the era of data-driven medicine: personalizing risks, diagnoses, treatments and prognoses.","date":"2020","source":"Briefings in bioinformatics","url":"https://pubmed.ncbi.nlm.nih.gov/31190075","citation_count":41,"is_preprint":false},{"pmid":"19539375","id":"PMC_19539375","title":"The deduced structure of the T cell receptor gamma locus in Canis lupus familiaris.","date":"2009","source":"Molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/19539375","citation_count":39,"is_preprint":false},{"pmid":"33751861","id":"PMC_33751861","title":"Exposure to violence, chronic stress, nasal DNA methylation, and atopic asthma in children.","date":"2021","source":"Pediatric pulmonology","url":"https://pubmed.ncbi.nlm.nih.gov/33751861","citation_count":33,"is_preprint":false},{"pmid":"22514632","id":"PMC_22514632","title":"MLN64 transport to the late endosome is regulated by binding to 14-3-3 via a non-canonical binding site.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22514632","citation_count":24,"is_preprint":false},{"pmid":"27068960","id":"PMC_27068960","title":"Touché! STARD3 and STARD3NL tether the ER to endosomes.","date":"2016","source":"Biochemical Society transactions","url":"https://pubmed.ncbi.nlm.nih.gov/27068960","citation_count":20,"is_preprint":false},{"pmid":"31047110","id":"PMC_31047110","title":"The role of microRNAs in chronic pseudomonas lung infection in Cystic fibrosis.","date":"2019","source":"Respiratory medicine","url":"https://pubmed.ncbi.nlm.nih.gov/31047110","citation_count":18,"is_preprint":false},{"pmid":"34532616","id":"PMC_34532616","title":"CRISPR-Cas9-Mediated Genome Editing Confirms EPDR1 as an Effector Gene at the BMD GWAS-Implicated 'STARD3NL' Locus.","date":"2021","source":"JBMR plus","url":"https://pubmed.ncbi.nlm.nih.gov/34532616","citation_count":14,"is_preprint":false},{"pmid":"31962062","id":"PMC_31962062","title":"Comprehensive genomic analysis of the dromedary T cell receptor gamma (TRG) locus and identification of a functional TRGC5 cassette.","date":"2020","source":"Developmental and comparative immunology","url":"https://pubmed.ncbi.nlm.nih.gov/31962062","citation_count":12,"is_preprint":false},{"pmid":"36534332","id":"PMC_36534332","title":"Association Between IL10 Polymorphisms and the Susceptibility to Sepsis: A Meta-Analysis.","date":"2022","source":"Biochemical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/36534332","citation_count":11,"is_preprint":false},{"pmid":"24116192","id":"PMC_24116192","title":"Atenolol induced HDL-C change in the pharmacogenomic evaluation of antihypertensive responses (PEAR) study.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24116192","citation_count":11,"is_preprint":false},{"pmid":"35098646","id":"PMC_35098646","title":"STARD3NL inhibits the osteogenic differentiation by inactivating the Wnt/β-catenin pathway via binding to Annexin A2 in osteoporosis.","date":"2022","source":"Journal of cellular and molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35098646","citation_count":6,"is_preprint":false},{"pmid":"33173928","id":"PMC_33173928","title":"Exposure to violence, chronic stress, nasal DNA methylation, and atopic asthma in children.","date":"2020","source":"medRxiv : the preprint server for health sciences","url":"https://pubmed.ncbi.nlm.nih.gov/33173928","citation_count":5,"is_preprint":false},{"pmid":"41895166","id":"PMC_41895166","title":"Integrated bioinformatics and machine learning, research on specific biomarkers for large-artery atherosclerosis stroke.","date":"2026","source":"Computational biology and chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/41895166","citation_count":0,"is_preprint":false},{"pmid":"41483826","id":"PMC_41483826","title":"Accelerating bone healing in femoral defect model using FBXO6-modified bone marrow-derived mesenchymal stem cells on a collagen scaffold.","date":"2026","source":"Biochemical pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/41483826","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":12024,"output_tokens":1692,"usd":0.030726,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8540,"output_tokens":2526,"usd":0.052925,"stage2_stop_reason":"end_turn"},"total_usd":0.083651,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"STARD3NL (MENTHO) is a late endosomal membrane protein synthesized as two isoforms (alpha: 234 aa, beta: 227 aa) that can be phosphorylated. It localizes to the membrane of late endosomes with its amino and carboxyl-terminal extremities projecting toward the cytoplasm. Overexpression leads to accumulation of enlarged endosomes, indicating an intrinsic biological function in endocytic transport beyond protein anchoring.\",\n      \"method\": \"cDNA cloning, subcellular fractionation/localization, overexpression with morphological readout\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — direct localization experiments with functional morphological consequence, single lab, multiple methods\",\n      \"pmids\": [\"12393907\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The MENTAL domain of STARD3NL (MENTHO) binds cholesterol in vivo, mediates homo-interaction of MENTHO, and mediates hetero-interaction between MENTHO and MLN64 (STARD3). GST pull-down and co-immunoprecipitation confirmed direct protein–protein interactions. FRET imaging with YFP/CFP fusion proteins in living cells confirmed MENTHO homo-interaction and interaction with MLN64 in late endosomal membranes.\",\n      \"method\": \"In vivo photocholesterol binding assay, GST pull-down, co-immunoprecipitation, FRET imaging with fluorescent fusion proteins\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal methods (in vivo cholesterol binding assay, GST pulldown, Co-IP, live-cell FRET) in single rigorous study\",\n      \"pmids\": [\"15718238\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"STARD3NL (MENTHO) and MLN64 share the MENTAL domain (four transmembrane helices), which targets both proteins to late endosomes, mediates homo- and hetero-interactions, and binds cholesterol in vivo, defining discrete cholesterol-containing subdomains within late endosomal membranes where they may function in cholesterol transport.\",\n      \"method\": \"Review/synthesis citing prior experimental data from the same group (cholesterol binding, Co-IP, localization)\",\n      \"journal\": \"Biochemical Society transactions\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — consolidates prior experimental findings; review article but grounded in published experimental data\",\n      \"pmids\": [\"16709157\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"STARD3NL, anchored on the limiting membrane of late endosomes, interacts directly with ER-anchored VAP proteins (VAP-A and VAP-B) to form ER–late endosome membrane contact sites (MCSs). These contacts affect endosome dynamics and are implicated in cholesterol transport.\",\n      \"method\": \"Protein interaction studies (implied by review citing primary data); membrane contact site characterization\",\n      \"journal\": \"Biochemical Society transactions\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — review article summarizing interaction data with VAP proteins and functional consequences on endosome dynamics; single lab\",\n      \"pmids\": [\"27068960\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"STARD3NL binds directly to Annexin A2 (ANXA2) and suppresses β-catenin expression, leading to inactivation of Wnt/β-catenin signaling and inhibition of osteogenic differentiation. Inhibition of Stard3nl induced nuclear translocation of β-catenin and activated Wnt signaling. In vivo, AAV9-mediated silencing of Stard3nl reversed bone loss in OVX-induced osteoporotic mice.\",\n      \"method\": \"Co-immunoprecipitation (Stard3nl–Anxa2 binding), loss-of-function (siRNA/shRNA knockdown), β-catenin nuclear translocation assay, Wnt reporter assay, in vivo AAV9 gene silencing in OVX mouse model\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — Co-IP for binding, functional KD with defined signaling readout, in vivo validation; single lab\",\n      \"pmids\": [\"35098646\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"FBXO6 (an E3 ubiquitin ligase) interacts with STARD3NL and promotes its destabilization (ubiquitin-mediated degradation). STARD3NL knockdown attenuated the impaired osteogenesis caused by FBXO6 silencing, placing STARD3NL downstream of FBXO6 in a pathway regulating osteoblast differentiation via Wnt/β-catenin signaling.\",\n      \"method\": \"Label-free quantitative proteomics, co-immunoprecipitation (FBXO6–STARD3NL), siRNA knockdown, osteogenic differentiation assays (ALP activity, calcium nodule formation), genetic epistasis (STARD3NL KD rescues FBXO6 KD phenotype)\",\n      \"journal\": \"Biochemical pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — proteomics identification plus Co-IP and epistasis rescue experiment; single lab, single study\",\n      \"pmids\": [\"41483826\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"STARD3NL (MENTHO) is a late endosomal membrane protein whose MENTAL domain binds cholesterol in vivo, mediates homo- and hetero-interactions with MLN64 (STARD3), and interacts with ER-resident VAP proteins to form ER–endosome membrane contact sites involved in cholesterol transport; in the context of bone biology, STARD3NL binds Annexin A2 to suppress Wnt/β-catenin signaling and inhibit osteogenesis, and is itself destabilized by the E3 ubiquitin ligase FBXO6.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"STARD3NL (MENTHO) is a late endosomal membrane protein that organizes cholesterol-containing subdomains of the endosomal limiting membrane and contributes to inter-organelle cholesterol transport [#0, #2]. It is anchored by a four-transmembrane MENTAL domain that both targets the protein to late endosomes and binds cholesterol in vivo; through this domain STARD3NL self-associates and forms hetero-interactions with the related protein MLN64/STARD3 within late endosomal membranes [#1, #2]. STARD3NL further bridges late endosomes to the endoplasmic reticulum by binding directly to the ER-anchored VAP proteins VAP-A and VAP-B, establishing ER\\u2013late endosome membrane contact sites that influence endosome dynamics [#3]. Independent of its endosomal role, STARD3NL acts in bone biology as a negative regulator of osteogenesis: it binds Annexin A2 (ANXA2) and suppresses \\u03b2-catenin, thereby inactivating Wnt/\\u03b2-catenin signaling and inhibiting osteogenic differentiation, with loss of STARD3NL activating Wnt signaling and reversing bone loss in vivo [#4]. STARD3NL protein levels are controlled by the E3 ubiquitin ligase FBXO6, which interacts with STARD3NL and promotes its ubiquitin-mediated degradation, placing STARD3NL downstream of FBXO6 in the control of osteoblast differentiation [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established STARD3NL as a bona fide late endosomal membrane protein with an intrinsic role in endocytic transport rather than a passive membrane anchor.\",\n      \"evidence\": \"cDNA cloning, subcellular fractionation/localization, and overexpression with a morphological (enlarged endosome) readout\",\n      \"pmids\": [\"12393907\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Molecular mechanism by which overexpression enlarges endosomes not defined\",\n        \"Functional consequence of the two phosphorylated isoforms unknown\"\n      ]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Defined the MENTAL domain as the functional unit, showing it binds cholesterol in vivo and mediates STARD3NL homo-interaction and hetero-interaction with MLN64/STARD3 in endosomal membranes.\",\n      \"evidence\": \"In vivo photocholesterol binding, GST pull-down, co-immunoprecipitation, and live-cell FRET with fluorescent fusion proteins\",\n      \"pmids\": [\"15718238\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Stoichiometry and structural basis of cholesterol binding not resolved\",\n        \"Functional output of the STARD3NL\\u2013MLN64 hetero-complex not established\"\n      ]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Consolidated the MENTAL domain model in which STARD3NL and MLN64 define discrete cholesterol-rich endosomal subdomains potentially functioning in cholesterol transport.\",\n      \"evidence\": \"Review synthesizing prior cholesterol-binding, Co-IP, and localization data from the same group\",\n      \"pmids\": [\"16709157\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct demonstration of cholesterol transport activity absent\",\n        \"No reconstitution of the proposed transport function\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Positioned STARD3NL as a tether linking late endosomes to the ER via direct binding to VAP-A and VAP-B, forming membrane contact sites that govern endosome dynamics.\",\n      \"evidence\": \"Protein interaction and membrane contact site characterization (review citing primary data)\",\n      \"pmids\": [\"27068960\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"FFAT-like motif mediating VAP binding not mapped in the timeline\",\n        \"Quantitative contribution of these contacts to cholesterol flux unmeasured\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Revealed a distinct signaling role in bone, where STARD3NL binds Annexin A2 to suppress \\u03b2-catenin and inhibit Wnt-driven osteogenesis, with in vivo relevance to osteoporosis.\",\n      \"evidence\": \"Co-IP, siRNA/shRNA knockdown, \\u03b2-catenin nuclear translocation and Wnt reporter assays, and AAV9 silencing in an OVX osteoporotic mouse model\",\n      \"pmids\": [\"35098646\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanistic link between ANXA2 binding and \\u03b2-catenin suppression unresolved\",\n        \"Whether this signaling role depends on STARD3NL's endosomal/cholesterol functions unknown\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Identified upstream control of STARD3NL abundance, showing FBXO6 targets it for ubiquitin-mediated degradation in a pathway regulating osteoblast differentiation.\",\n      \"evidence\": \"Label-free proteomics, FBXO6\\u2013STARD3NL Co-IP, knockdown, osteogenic differentiation assays, and epistasis rescue\",\n      \"pmids\": [\"41483826\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Ubiquitination site(s) on STARD3NL not mapped\",\n        \"Whether FBXO6 regulates the endosomal/cholesterol functions of STARD3NL untested\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How STARD3NL's endosomal cholesterol-transport function mechanistically relates to its Wnt/osteogenic signaling role, and whether the two are coupled, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No unified model linking cholesterol/MCS function to Wnt regulation\",\n        \"Direct cholesterol-transport activity not biochemically demonstrated\",\n        \"Structural data on the MENTAL domain and its ligand/partner interfaces absent\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [0, 1, 3]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [4, 5]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"STARD3\", \"VAPA\", \"VAPB\", \"ANXA2\", \"FBXO6\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}