{"gene":"TNFRSF11B","run_date":"2026-06-10T10:51:55","timeline":{"discoveries":[{"year":2002,"finding":"A 3-bp in-frame deletion in TNFRSF11B (loss of an aspartate residue) results in a mutant OPG protein that fails to suppress bone resorption in vitro, establishing this as an inactivating mutation. Wild-type OPG expressed in human epithelial kidney cells and collected from conditioned medium suppressed bone resorption, whereas the mutant form did not.","method":"Recombinant wild-type and mutant OPG cDNA expression in human epithelial kidney cells, conditioned medium collection, in vitro bone resorption assay","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct in vitro functional assay with wild-type vs. mutant comparison, reconstitution in cell system with clear phenotypic readout","pmids":["12189164"],"is_preprint":false},{"year":2003,"finding":"Mutations in the cysteine-rich ligand-binding domain of OPG (encoded by TNFRSF11B) disrupt binding to RANKL. Missense mutations at cysteine residues cause the most severe phenotype (predicted major disruption to ligand-binding), while non-cysteine missense mutations in the same domain cause intermediate phenotype, and a C-terminal insertion/deletion causes the mildest phenotype, establishing a genotype-phenotype correlation linked to the degree of RANKL-binding disruption.","method":"Mutation analysis of TNFRSF11B in affected families, predicted structural effects on OPG ligand-binding domain correlated with clinical phenotype severity","journal":"Journal of bone and mineral research","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — genotype-phenotype correlation across multiple families with predicted (not directly measured) functional effects; no in vitro binding assay performed","pmids":["14672344"],"is_preprint":false},{"year":2005,"finding":"A truncating mutation in TNFRSF11B (homozygous insertion/deletion in exon 5, truncating protein at amino acid 325) eliminates the C-terminal domain, abolishes OPG homodimerization, and decreases the capacity of mutant OPG to bind RANKL, as confirmed by Western blotting and ELISA after transient overexpression.","method":"Transient overexpression of mutant OPG, Western blotting for homodimerization, ELISA for RANKL-binding capacity","journal":"Bone","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct functional assays (Western blot for dimerization, ELISA for ligand binding) with mutant vs. wild-type comparison in overexpression system","pmids":["15777670"],"is_preprint":false},{"year":2007,"finding":"The TNFRSF11B 'Balkan' mutation (966_969delTGACinsCTT) causes a frameshift that deletes 79 C-terminal amino acids from the OPG monomer, including a cysteine residue required for homodimerization, resulting in truncated monomeric OPG that cannot form homodimers yet is still detectable as elevated circulating immunoreactive OPG along with elevated soluble RANKL.","method":"TNFRSF11B sequencing, serum immunoreactive OPG and soluble RANKL ELISA measurement over 4 years","journal":"Journal of bone and mineral research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — ELISA measurement of circulating protein in a single patient; structural inference about dimerization from sequence analysis is consistent with prior in vitro data but not directly re-tested here","pmids":["17352649"],"is_preprint":false},{"year":2011,"finding":"The T allele of the C950T (rs2073617) promoter polymorphism in TNFRSF11B drives lower luciferase reporter expression in HeLa, COS-7, and RAW264.7 cell lines compared to the C allele, indicating a functional cis-regulatory effect on OPG transcription. Additionally, the C allele of rs4876869 causes exon skipping in a pre-mRNA splicing assay, reducing full-length OPG transcript.","method":"Promoter-luciferase reporter assay in three cell lines; exon-trapping splicing assay for rs4876869","journal":"Journal of molecular endocrinology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — two orthogonal functional assays (luciferase reporter + splicing assay) in multiple cell lines, single lab","pmids":["21994215"],"is_preprint":false},{"year":2013,"finding":"Human metastatic melanomas constitutively produce OPG (TNFRSF11B product) through a mechanism governed by membrane-bound TNF-α signaling through TNF receptor 1 (TNFR1), defining a specific regulatory axis controlling OPG production in tumor cells.","method":"Characterization of OPG production by melanoma cell lines; identification of membrane-bound TNF-α/TNFR1 signaling as the regulating mechanism","journal":"Pigment cell & melanoma research","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — mechanistic pathway identification in cell lines, single lab, limited methodological detail in abstract","pmids":["23490134"],"is_preprint":false},{"year":2014,"finding":"A heterozygous read-through mutation (c.1205A>T; p.Stop402Leu) in TNFRSF11B results in a gain-of-function OPG with enhanced capacity to inhibit osteoclastogenesis and bone resorption in a cell-based bone resorption assay, causing familial early-onset OA with chondrocalcinosis.","method":"Cell-based bone resorption assay comparing mutant vs. wild-type OPG; exome sequencing and linkage analysis for mutation identification","journal":"Annals of the rheumatic diseases","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — cell-based functional assay with clear wild-type vs. mutant comparison, single lab, limited to one assay type","pmids":["24743232"],"is_preprint":false},{"year":2015,"finding":"Circadian expression of Tnfrsf11b (OPG) in osteoblasts is regulated by the clock genes Bmal1 and REV-ERBα (Nr1d1): Bmal1 positively regulates rhythmic Tnfrsf11b expression and REV-ERBα negatively regulates it. α1B-adrenergic receptor signaling controls this circadian regulation, as genetic ablation of α1B-AR alters Tnfrsf11b expression concomitant with Bmal1 and Per2 in bone.","method":"Loss-of-function and gain-of-function experiments in MC3T3-E1 osteoblast cells; pharmacological stimulation with phenylephrine (α1-AR agonist); genetic ablation of α1B-AR in mice with in vivo bone expression analysis","journal":"Biology open","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal approaches (in vitro gain/loss-of-function, in vivo genetic ablation, pharmacological), single lab","pmids":["26453621"],"is_preprint":false},{"year":2016,"finding":"TNFRSF11B is a direct target of miR-145 in chondrocytes, as confirmed by dual-luciferase reporter assay. miR-145 overexpression suppresses TNFRSF11B expression and inhibits chondrocyte proliferation and fibrosis; siRNA knockdown of TNFRSF11B phenocopies this inhibition.","method":"Dual-luciferase reporter assay for miR-145 targeting; miR-145 mimic transfection; siRNA knockdown of TNFRSF11B; MTT proliferation assay; Western blot for fibrosis markers","journal":"Molecular medicine reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — dual-luciferase assay validates direct targeting, with siRNA knockdown phenocopying mimic overexpression; single lab, two orthogonal methods","pmids":["27922673"],"is_preprint":false},{"year":2020,"finding":"TNFRSF11B (OPG) directly binds GSK-3β and upregulates its phosphorylation, leading to increased nuclear β-catenin and activation of Wnt/β-catenin downstream effectors in gastric cancer cells, promoting proliferation, migration, invasion, and inhibiting apoptosis.","method":"Co-immunoprecipitation (TNFRSF11B–GSK-3β interaction); immunofluorescence for nuclear β-catenin; Western blot for β-catenin and downstream effectors; in vitro and in vivo functional assays (proliferation, migration, invasion, apoptosis)","journal":"International journal of biological sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP for binding partner identification plus multiple functional readouts; single lab","pmids":["32398963"],"is_preprint":false},{"year":2021,"finding":"The OPG-XL (read-through/gain-of-function) mutation in TNFRSF11B is actually a loss-of-function mutation with respect to RANKL-mediated osteoclastogenesis: recombinant OPG-XL is less effective than wild-type OPG at blocking RANKL-induced osteoclastogenesis in monoculture and coculture models, and significantly less OPG-XL binds to osteoblastic cells. Effects on osteoclast survival and TRAIL-induced apoptosis were similar to wild-type OPG.","method":"In vitro RANKL-induced osteoclastogenesis in monoculture and coculture; osteoclast survival assay; TRAIL-induced apoptosis assay; ELISA and flow cytometry for OPG binding to MC3T3-E1 osteoblastic cells","journal":"Arthritis & rheumatology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — multiple in vitro functional assays (osteoclastogenesis, survival, apoptosis, binding) with recombinant proteins, direct comparison of mutant vs. wild-type","pmids":["33559312"],"is_preprint":false},{"year":2021,"finding":"Overexpression of TNFRSF11B in primary human articular chondrocytes in a 3D in vitro chondrogenesis model strongly upregulates MMP13, COL2A1, COL1A1, and osteoblast markers RUNX2, ASPN, and OGN, and increases mineralization, suggesting OPG drives chondrocyte-to-osteoblast transition in OA. Notably, RANK and RANKL expression remained unchanged, indicating downstream pathways in cartilage independent of the OPG/RANK/RANKL triad.","method":"Lentiviral overexpression of TNFRSF11B in primary chondrocytes; 3D chondrogenic culture model; RT-qPCR; immunohistochemistry; ELISA; Alcian blue staining; RNA-seq correlation analysis","journal":"Rheumatology (Oxford, England)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (RT-qPCR, IHC, ELISA, histological staining) in a defined 3D functional model; single lab","pmids":["33989379"],"is_preprint":false},{"year":2021,"finding":"TAp63 regulates bone remodeling by modulating the expression of TNFRSF11B/osteoprotegerin.","method":"Not fully detailed in abstract; implied transcriptional regulation study","journal":"Cell cycle","confidence":"Low","confidence_rationale":"Tier 4 / Weak — abstract is a stub with no experimental details provided; cannot assess methods or rigor","pmids":["34763601"],"is_preprint":false},{"year":2024,"finding":"TNFRSF11B promotes bladder cancer cell proliferation, migration, invasion, and EMT, and inhibits apoptosis via activation of the PI3K/AKT pathway; inhibition of PI3K/AKT with LY294002 reverses the effects of TNFRSF11B overexpression.","method":"siRNA knockdown and overexpression of TNFRSF11B in bladder cancer cells; Western blot for PI3K/AKT pathway markers and EMT markers; cell proliferation, migration, and invasion assays; apoptosis assay; in vivo tumor assay; LY294002 pharmacological inhibition","journal":"Molecular and cellular probes","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — pathway placement via pharmacological inhibitor rescue and multiple functional readouts; single lab, no reconstitution or structural data","pmids":["39481664"],"is_preprint":false},{"year":2025,"finding":"TNFRSF11B overexpression in UCMSCs suppresses RANKL-induced osteoclast differentiation (via conditioned medium), but neither overexpression of TNFRSF11B nor treatment with exogenous OPG protein enhances osteogenic differentiation of UCMSCs in vitro. Proteomic analysis of conditioned medium from TNFRSF11B-overexpressing UCMSCs identified downregulation of C1R, MDH1, and ACLY and upregulation of FETUB and METRNL, associated with osteoclast inhibition.","method":"Lentiviral overexpression in UCMSCs; conditioned medium treatment of osteoclast precursors; ALP staining; TRAP staining; qRT-PCR; proteomic analysis","journal":"Journal of orthopaedic surgery and research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — multiple assays in a defined cell model with negative finding for osteogenesis clearly stated; single lab, single publication","pmids":["40380204"],"is_preprint":false},{"year":2026,"finding":"CRISPR/Cas9 knock-in of the TNFRSF11B mutation (OPGmt) in mice produces osteopenia, elevated bone remodeling markers, increased osteoclast numbers and activity, and in female homozygous mice, osteoarthritis features (articular cartilage loss) by 12 months. Joints of OPGmt mice showed elevated pyrophosphate, TGF-β1, and ENPP1 activity — biomarkers of CPPD disease — establishing the mutation as a loss-of-function driving increased osteoclastogenesis and CPPD-related joint pathology.","method":"CRISPR/Cas9 knock-in murine model; histological scoring (Mankin); bone remodeling biomarkers; osteoclast number/activity assays; CPPD biomarker measurement (pyrophosphate, TGF-β1, ENPP1 activity) at 6 and 12 months","journal":"Annals of the rheumatic diseases","confidence":"High","confidence_rationale":"Tier 1 / Moderate — CRISPR/Cas9 knock-in model with multiple orthogonal in vivo phenotypic, histological, and biochemical readouts; recapitulates human disease features","pmids":["41826214"],"is_preprint":false}],"current_model":"TNFRSF11B encodes osteoprotegerin (OPG), a soluble decoy receptor that binds RANKL via its cysteine-rich N-terminal domain and inhibits osteoclast differentiation and bone resorption; OPG forms homodimers via a C-terminal cysteine required for full activity, and loss-of-function mutations (deletions, cysteine-disrupting missense, truncations) abolish RANKL binding and/or dimerization causing uncontrolled osteoclastogenesis (juvenile Paget's disease), while a gain-of-function read-through mutation causes enhanced osteoclast inhibition leading to OA with chondrocalcinosis; in non-skeletal contexts OPG activates Wnt/β-catenin signaling in gastric cancer through direct binding and phosphorylation of GSK-3β, promotes bladder cancer via PI3K/AKT, is regulated transcriptionally by clock genes (Bmal1, REV-ERBα) downstream of α1B-adrenergic signaling in osteoblasts, is a direct miR-145 target in chondrocytes, and in OA cartilage drives chondrocyte-to-osteoblast transition independently of the RANKL/RANK axis."},"narrative":{"mechanistic_narrative":"TNFRSF11B encodes osteoprotegerin (OPG), a secreted decoy receptor that restrains osteoclast differentiation and bone resorption by sequestering RANKL, with its activity depending on an N-terminal cysteine-rich ligand-binding domain and C-terminal cysteine-mediated homodimerization [PMID:12189164, PMID:15777670]. Loss-of-function mutations operate through two convergent mechanisms: missense changes in the cysteine-rich domain disrupt RANKL binding with severity scaling to the degree of binding loss, while truncating/frameshift mutations remove the C-terminal cysteine, abolish homodimerization, and reduce RANKL-binding capacity, releasing osteoclastogenesis from inhibition [PMID:14672344, PMID:15777670, PMID:17352649]. A knock-in murine model recapitulates this, producing osteopenia, elevated bone remodeling, increased osteoclast activity, and CPPD-associated joint pathology [PMID:41826214]. A read-through allele (OPG-XL), once classified as gain-of-function, behaves as loss-of-function for RANKL-mediated osteoclastogenesis with reduced binding to osteoblastic cells [PMID:24743232, PMID:33559312]. OPG expression is controlled at multiple levels — by functional promoter and splicing polymorphisms [PMID:21994215], by circadian clock genes Bmal1 and REV-ERBα downstream of α1B-adrenergic signaling in osteoblasts [PMID:26453621], and by miR-145 in chondrocytes [PMID:27922673]. Beyond the skeletal RANKL axis, OPG drives a chondrocyte-to-osteoblast transition in articular cartilage independently of RANK/RANKL [PMID:33989379], and in tumors it activates Wnt/β-catenin signaling via direct binding and phosphorylation of GSK-3β in gastric cancer [PMID:32398963] and the PI3K/AKT pathway in bladder cancer [PMID:39481664].","teleology":[{"year":2002,"claim":"Established that disease-associated TNFRSF11B mutations act by abolishing OPG's functional ability to suppress bone resorption, defining the gene's loss-of-function mechanism.","evidence":"Recombinant wild-type vs. mutant OPG from HEK conditioned medium in an in vitro bone resorption assay","pmids":["12189164"],"confidence":"High","gaps":["Did not resolve whether the defect was in RANKL binding, dimerization, or secretion","Single mutation tested"]},{"year":2003,"claim":"Resolved a genotype-phenotype correlation by linking mutation location within the cysteine-rich ligand-binding domain to severity of RANKL-binding disruption.","evidence":"Mutation analysis across affected families with structural prediction correlated to clinical severity","pmids":["14672344"],"confidence":"Medium","gaps":["Functional effects predicted, not directly measured by binding assay","No structural model verified"]},{"year":2005,"claim":"Demonstrated that C-terminal truncation abolishes OPG homodimerization and reduces RANKL binding, mechanistically tying dimerization to full activity.","evidence":"Transient overexpression with Western blot for dimerization and ELISA for RANKL binding","pmids":["15777670"],"confidence":"High","gaps":["Did not quantify residual monomer activity in vivo","Single truncating allele"]},{"year":2007,"claim":"Showed a frameshift removing the dimerization cysteine yields monomeric OPG yet still elevated circulating immunoreactive protein, clarifying that immunoassay levels do not reflect functional activity.","evidence":"Sequencing plus longitudinal serum OPG and soluble RANKL ELISA in a patient","pmids":["17352649"],"confidence":"Medium","gaps":["Dimerization inferred from sequence, not re-tested directly","Single patient"]},{"year":2011,"claim":"Identified functional cis-regulatory variants controlling OPG transcription and splicing, extending genetic risk beyond coding mutations.","evidence":"Promoter-luciferase reporter in three cell lines and an exon-trapping splicing assay","pmids":["21994215"],"confidence":"High","gaps":["Effect on endogenous OPG protein levels in bone not measured","Trans-acting factors driving promoter activity unidentified"]},{"year":2013,"claim":"Defined an upstream regulatory axis for OPG production in tumor cells, implicating membrane-bound TNF-α/TNFR1 signaling.","evidence":"Characterization of OPG production in melanoma cell lines with pathway dissection","pmids":["23490134"],"confidence":"Medium","gaps":["Limited methodological detail","Functional consequence of tumor OPG not established here"]},{"year":2014,"claim":"Initially characterized a read-through allele as gain-of-function with enhanced osteoclastogenesis inhibition causing early-onset OA with chondrocalcinosis.","evidence":"Cell-based bone resorption assay comparing mutant vs. wild-type OPG, with exome sequencing and linkage","pmids":["24743232"],"confidence":"Medium","gaps":["Single assay type","Mechanism linking enhanced inhibition to chondrocalcinosis unexplained"]},{"year":2015,"claim":"Placed OPG transcription under circadian control, linking α1B-adrenergic signaling and clock genes to rhythmic bone gene expression.","evidence":"Gain/loss-of-function in MC3T3-E1 cells, phenylephrine stimulation, and α1B-AR knockout mice","pmids":["26453621"],"confidence":"Medium","gaps":["Direct promoter occupancy by Bmal1/REV-ERBα not shown","Physiological consequence for bone mass not quantified"]},{"year":2016,"claim":"Identified miR-145 as a direct post-transcriptional repressor of TNFRSF11B in chondrocytes affecting proliferation and fibrosis.","evidence":"Dual-luciferase reporter, miR-145 mimic, and TNFRSF11B siRNA phenocopy in chondrocytes","pmids":["27922673"],"confidence":"Medium","gaps":["In vivo relevance not established","Single cell type"]},{"year":2020,"claim":"Revealed a non-canonical, RANKL-independent OPG function: direct binding and phosphorylation of GSK-3β to activate Wnt/β-catenin signaling in gastric cancer.","evidence":"Co-IP of OPG–GSK-3β, immunofluorescence for nuclear β-catenin, and functional cancer assays","pmids":["32398963"],"confidence":"Medium","gaps":["Single Co-IP without reciprocal/structural validation","How a secreted decoy accesses cytoplasmic GSK-3β unresolved"]},{"year":2021,"claim":"Reclassified the OPG-XL read-through allele as loss-of-function for RANKL-mediated osteoclastogenesis with reduced binding to osteoblastic cells, overturning the earlier gain-of-function model.","evidence":"Recombinant OPG-XL vs. wild-type in osteoclastogenesis monoculture/coculture, survival, apoptosis, and binding assays","pmids":["33559312"],"confidence":"High","gaps":["Mechanism connecting reduced binding to chondrocalcinosis phenotype unresolved","Effect on TRAIL/survival unchanged, leaving disease driver partly open"]},{"year":2021,"claim":"Demonstrated OPG drives chondrocyte-to-osteoblast transition in articular cartilage through pathways independent of the RANK/RANKL triad.","evidence":"Lentiviral TNFRSF11B overexpression in primary chondrocytes in a 3D chondrogenesis model with RT-qPCR, IHC, and mineralization assays","pmids":["33989379"],"confidence":"Medium","gaps":["Downstream effector pathway in cartilage not identified","Receptor/binding partner mediating the effect unknown"]},{"year":2021,"claim":"Implicated TAp63 as a transcriptional regulator of TNFRSF11B in bone remodeling.","evidence":"Implied transcriptional regulation study (abstract stub)","pmids":["34763601"],"confidence":"Low","gaps":["No experimental detail available to assess rigor","Direct promoter binding not demonstrated"]},{"year":2024,"claim":"Placed OPG's pro-tumor activity in bladder cancer downstream of PI3K/AKT signaling via inhibitor rescue.","evidence":"Knockdown/overexpression in bladder cancer cells with LY294002 rescue, EMT markers, and in vivo tumor assay","pmids":["39481664"],"confidence":"Medium","gaps":["No direct binding partner for pathway activation identified","Single lab, no structural data"]},{"year":2025,"claim":"Showed OPG overexpression suppresses osteoclastogenesis but does not promote osteogenesis, and identified secreted proteomic mediators associated with osteoclast inhibition.","evidence":"Lentiviral overexpression in UCMSCs, conditioned medium osteoclast/osteogenic assays, and conditioned-medium proteomics","pmids":["40380204"],"confidence":"Medium","gaps":["Causal role of identified proteins (C1R, FETUB, METRNL) not tested","Single cell model"]},{"year":2026,"claim":"Provided in vivo causal confirmation that the TNFRSF11B mutation is loss-of-function, driving osteopenia, increased osteoclastogenesis, and CPPD-related joint pathology.","evidence":"CRISPR/Cas9 knock-in mouse with histology, bone remodeling and osteoclast assays, and CPPD biomarker measurement","pmids":["41826214"],"confidence":"High","gaps":["Molecular link from OPG loss to pyrophosphate/ENPP1 elevation not fully resolved","Sex-specific OA penetrance unexplained"]},{"year":null,"claim":"The receptor and downstream effector pathway mediating OPG's RANKL-independent actions in cartilage and tumors remain undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No cell-surface receptor for non-canonical OPG signaling identified","Structural basis for OPG–GSK-3β interaction unknown","Reconciliation of decoy versus signaling roles incomplete"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,2,10]},{"term_id":"GO:0140313","term_label":"molecular sequestering activity","supporting_discovery_ids":[2,3]}],"localization":[{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[0,3]}],"pathway":[{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[0,15]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[9,13]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[15,9,13]}],"complexes":[],"partners":["RANKL","GSK-3Β"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O00300","full_name":"Tumor necrosis factor receptor superfamily member 11B","aliases":["Osteoclastogenesis inhibitory factor","Osteoprotegerin"],"length_aa":401,"mass_kda":46.0,"function":"Acts as a decoy receptor for TNFSF11/RANKL and thereby neutralizes its function in osteoclastogenesis. Inhibits the activation of osteoclasts and promotes osteoclast apoptosis in vitro. Bone homeostasis seems to depend on the local ratio between TNFSF11 and TNFRSF11B. May also play a role in preventing arterial calcification. May act as decoy receptor for TNFSF10/TRAIL and protect against apoptosis. TNFSF10/TRAIL binding blocks the inhibition of osteoclastogenesis","subcellular_location":"Secreted","url":"https://www.uniprot.org/uniprotkb/O00300/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TNFRSF11B","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/TNFRSF11B","total_profiled":1310},"omim":[{"mim_id":"619820","title":"ATONAL bHLH TRANSCRIPTION FACTOR 8; ATOH8","url":"https://www.omim.org/entry/619820"},{"mim_id":"612113","title":"BONE MINERAL DENSITY QUANTITATIVE TRAIT LOCUS 10; BMND10","url":"https://www.omim.org/entry/612113"},{"mim_id":"610830","title":"POLYOSTEOLYSIS-HYPEROSTOSIS SYNDROME","url":"https://www.omim.org/entry/610830"},{"mim_id":"607507","title":"PSORIATIC ARTHRITIS, SUSCEPTIBILITY TO","url":"https://www.omim.org/entry/607507"},{"mim_id":"602643","title":"TUMOR NECROSIS FACTOR RECEPTOR SUPERFAMILY, MEMBER 11B; TNFRSF11B","url":"https://www.omim.org/entry/602643"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Golgi apparatus","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Nucleoli","reliability":"Additional"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"blood vessel","ntpm":192.4},{"tissue":"thyroid gland","ntpm":95.4}],"url":"https://www.proteinatlas.org/search/TNFRSF11B"},"hgnc":{"alias_symbol":["OCIF","TR1"],"prev_symbol":["OPG"]},"alphafold":{"accession":"O00300","domains":[{"cath_id":"2.10.50.10","chopping":"24-107","consensus_level":"medium","plddt":95.7445,"start":24,"end":107},{"cath_id":"2.10.50.10","chopping":"110-187","consensus_level":"medium","plddt":91.8129,"start":110,"end":187},{"cath_id":"-","chopping":"196-390","consensus_level":"medium","plddt":88.9079,"start":196,"end":390}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O00300","model_url":"https://alphafold.ebi.ac.uk/files/AF-O00300-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O00300-F1-predicted_aligned_error_v6.png","plddt_mean":86.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TNFRSF11B","jax_strain_url":"https://www.jax.org/strain/search?query=TNFRSF11B"},"sequence":{"accession":"O00300","fasta_url":"https://rest.uniprot.org/uniprotkb/O00300.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O00300/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O00300"}},"corpus_meta":[{"pmid":"12189164","id":"PMC_12189164","title":"A mutation in the gene TNFRSF11B encoding osteoprotegerin causes an idiopathic hyperphosphatasia phenotype.","date":"2002","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/12189164","citation_count":165,"is_preprint":false},{"pmid":"14672344","id":"PMC_14672344","title":"Idiopathic hyperphosphatasia and TNFRSF11B mutations: relationships between phenotype and genotype.","date":"2003","source":"Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research","url":"https://pubmed.ncbi.nlm.nih.gov/14672344","citation_count":87,"is_preprint":false},{"pmid":"21903966","id":"PMC_21903966","title":"Assessment of the genetic effects of polymorphisms in the osteoprotegerin gene, TNFRSF11B, on serum osteoprotegerin levels and carotid plaque vulnerability.","date":"2011","source":"Stroke","url":"https://pubmed.ncbi.nlm.nih.gov/21903966","citation_count":54,"is_preprint":false},{"pmid":"24743232","id":"PMC_24743232","title":"A gain of function mutation in TNFRSF11B encoding osteoprotegerin causes osteoarthritis with chondrocalcinosis.","date":"2014","source":"Annals of the rheumatic diseases","url":"https://pubmed.ncbi.nlm.nih.gov/24743232","citation_count":48,"is_preprint":false},{"pmid":"17388729","id":"PMC_17388729","title":"Identification of sex-specific associations between polymorphisms of the osteoprotegerin gene, TNFRSF11B, and Paget's disease of bone.","date":"2007","source":"Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research","url":"https://pubmed.ncbi.nlm.nih.gov/17388729","citation_count":46,"is_preprint":false},{"pmid":"32398963","id":"PMC_32398963","title":"TNFRSF11B activates Wnt/β-catenin signaling and promotes gastric cancer 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HIVE-control patients.","date":"2010","source":"Journal of inflammation (London, England)","url":"https://pubmed.ncbi.nlm.nih.gov/20920282","citation_count":19,"is_preprint":false},{"pmid":"25108083","id":"PMC_25108083","title":"Novel homozygous mutations in the osteoprotegerin gene TNFRSF11B in two unrelated patients with juvenile Paget's disease.","date":"2014","source":"Bone","url":"https://pubmed.ncbi.nlm.nih.gov/25108083","citation_count":19,"is_preprint":false},{"pmid":"27922673","id":"PMC_27922673","title":"Effects of miR-145 on the inhibition of chondrocyte proliferation and fibrosis by targeting TNFRSF11B in human osteoarthritis.","date":"2016","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/27922673","citation_count":17,"is_preprint":false},{"pmid":"25323794","id":"PMC_25323794","title":"TNFRSF11B gene polymorphisms, bone mineral density, and fractures in Slovak postmenopausal women.","date":"2014","source":"Journal of applied 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journal of the Human Biology Council","url":"https://pubmed.ncbi.nlm.nih.gov/24130145","citation_count":11,"is_preprint":false},{"pmid":"33559312","id":"PMC_33559312","title":"Effects of the TNFRSF11B Mutation Associated With Calcium Pyrophosphate Deposition Disease in Osteoclastogenesis in a Murine Model.","date":"2021","source":"Arthritis & rheumatology (Hoboken, N.J.)","url":"https://pubmed.ncbi.nlm.nih.gov/33559312","citation_count":10,"is_preprint":false},{"pmid":"26453621","id":"PMC_26453621","title":"α1B-Adrenergic receptor signaling controls circadian expression of Tnfrsf11b by regulating clock genes in osteoblasts.","date":"2015","source":"Biology open","url":"https://pubmed.ncbi.nlm.nih.gov/26453621","citation_count":9,"is_preprint":false},{"pmid":"29749489","id":"PMC_29749489","title":"Effects of osteoprotegerin/TNFRSF11B in two models of abdominal aortic aneurysms.","date":"2018","source":"Molecular medicine 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studies.","date":"2021","source":"Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA","url":"https://pubmed.ncbi.nlm.nih.gov/34716467","citation_count":6,"is_preprint":false},{"pmid":"22079369","id":"PMC_22079369","title":"TNFRSF11B gene haplotype and its association with bone mineral density variations in postmenopausal Mexican-Mestizo women.","date":"2011","source":"Maturitas","url":"https://pubmed.ncbi.nlm.nih.gov/22079369","citation_count":5,"is_preprint":false},{"pmid":"31655221","id":"PMC_31655221","title":"Juvenile Paget's disease with compound heterozygous mutations in TNFRSF11B presenting with recurrent clavicular fractures and a mild skeletal phenotype.","date":"2019","source":"Bone","url":"https://pubmed.ncbi.nlm.nih.gov/31655221","citation_count":5,"is_preprint":false},{"pmid":"39481664","id":"PMC_39481664","title":"TNFRSF11B promotes the progression of bladder cancer through PI3K/AKT signaling pathway.","date":"2024","source":"Molecular and cellular probes","url":"https://pubmed.ncbi.nlm.nih.gov/39481664","citation_count":4,"is_preprint":false},{"pmid":"25032118","id":"PMC_25032118","title":"Exclusion of TNFRSF11B as Candidate Gene for Otosclerosis in Campania Population.","date":"2014","source":"Indian journal of otolaryngology and head and neck surgery : official publication of the Association of Otolaryngologists of India","url":"https://pubmed.ncbi.nlm.nih.gov/25032118","citation_count":4,"is_preprint":false},{"pmid":"34763601","id":"PMC_34763601","title":"TAp63 regulates bone remodeling by modulating the expression of TNFRSF11B/Osteoprotegerin.","date":"2021","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/34763601","citation_count":4,"is_preprint":false},{"pmid":"31658533","id":"PMC_31658533","title":"[Association between TNFRSF11A and TNFRSF11B gene polymorphisms and the outcome of hepatitis C virus infection].","date":"2019","source":"Zhonghua liu xing bing xue za zhi = Zhonghua liuxingbingxue zazhi","url":"https://pubmed.ncbi.nlm.nih.gov/31658533","citation_count":3,"is_preprint":false},{"pmid":"40380204","id":"PMC_40380204","title":"TNFRSF11B-modified umbilical cord mesenchymal stem cells as a novel strategy for bone-related diseases by suppressing osteoclast activity.","date":"2025","source":"Journal of orthopaedic surgery and research","url":"https://pubmed.ncbi.nlm.nih.gov/40380204","citation_count":2,"is_preprint":false},{"pmid":"40775369","id":"PMC_40775369","title":"Juvenile Paget disease with unique compound heterozygous sequence variants in the TNFRSF11B gene.","date":"2025","source":"Orphanet journal of rare diseases","url":"https://pubmed.ncbi.nlm.nih.gov/40775369","citation_count":1,"is_preprint":false},{"pmid":"37481965","id":"PMC_37481965","title":"Establishment of a TNFRSF11B knock-out human induced pluripotent stem cell line (KSCBi002-B-2) via CRISPR/Cas9 system.","date":"2023","source":"Stem cell research","url":"https://pubmed.ncbi.nlm.nih.gov/37481965","citation_count":1,"is_preprint":false},{"pmid":"34166796","id":"PMC_34166796","title":"Juvenile Paget's Disease: Report of a successful treatment throughout the complete growth of a patient with a missense TNFRSF11B mutation.","date":"2021","source":"Joint bone spine","url":"https://pubmed.ncbi.nlm.nih.gov/34166796","citation_count":1,"is_preprint":false},{"pmid":"40623930","id":"PMC_40623930","title":"[Association of TNFRSF11B gene rs2073618 and rs3102735 polymorphisms with susceptibility to Gastric cancer].","date":"2025","source":"Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/40623930","citation_count":0,"is_preprint":false},{"pmid":"41009461","id":"PMC_41009461","title":"The Influence of Clinical Factors and Genetic Variants of COL1A1 and TNFRSF11B on Bone Mineral Density in Postmenopausal Women.","date":"2025","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/41009461","citation_count":0,"is_preprint":false},{"pmid":"41826214","id":"PMC_41826214","title":"A novel murine model of early calcium pyrophosphate deposition disease based on the TNFRSF11B mutation mimics features of the human disease.","date":"2026","source":"Annals of the rheumatic diseases","url":"https://pubmed.ncbi.nlm.nih.gov/41826214","citation_count":0,"is_preprint":false},{"pmid":"41728123","id":"PMC_41728123","title":"TNFRSF11B modulates Marek's disease virus infection by regulating apoptosis in chicken embryo fibroblasts.","date":"2026","source":"Frontiers in veterinary science","url":"https://pubmed.ncbi.nlm.nih.gov/41728123","citation_count":0,"is_preprint":false},{"pmid":"23772656","id":"PMC_23772656","title":"TNFRSF11B polymorphisms are associated with metabolic traits in Uyghur and Han ethnic groups.","date":"2013","source":"Endocrine 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Wild-type OPG expressed in human epithelial kidney cells and collected from conditioned medium suppressed bone resorption, whereas the mutant form did not.\",\n      \"method\": \"Recombinant wild-type and mutant OPG cDNA expression in human epithelial kidney cells, conditioned medium collection, in vitro bone resorption assay\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct in vitro functional assay with wild-type vs. mutant comparison, reconstitution in cell system with clear phenotypic readout\",\n      \"pmids\": [\"12189164\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Mutations in the cysteine-rich ligand-binding domain of OPG (encoded by TNFRSF11B) disrupt binding to RANKL. Missense mutations at cysteine residues cause the most severe phenotype (predicted major disruption to ligand-binding), while non-cysteine missense mutations in the same domain cause intermediate phenotype, and a C-terminal insertion/deletion causes the mildest phenotype, establishing a genotype-phenotype correlation linked to the degree of RANKL-binding disruption.\",\n      \"method\": \"Mutation analysis of TNFRSF11B in affected families, predicted structural effects on OPG ligand-binding domain correlated with clinical phenotype severity\",\n      \"journal\": \"Journal of bone and mineral research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — genotype-phenotype correlation across multiple families with predicted (not directly measured) functional effects; no in vitro binding assay performed\",\n      \"pmids\": [\"14672344\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"A truncating mutation in TNFRSF11B (homozygous insertion/deletion in exon 5, truncating protein at amino acid 325) eliminates the C-terminal domain, abolishes OPG homodimerization, and decreases the capacity of mutant OPG to bind RANKL, as confirmed by Western blotting and ELISA after transient overexpression.\",\n      \"method\": \"Transient overexpression of mutant OPG, Western blotting for homodimerization, ELISA for RANKL-binding capacity\",\n      \"journal\": \"Bone\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct functional assays (Western blot for dimerization, ELISA for ligand binding) with mutant vs. wild-type comparison in overexpression system\",\n      \"pmids\": [\"15777670\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"The TNFRSF11B 'Balkan' mutation (966_969delTGACinsCTT) causes a frameshift that deletes 79 C-terminal amino acids from the OPG monomer, including a cysteine residue required for homodimerization, resulting in truncated monomeric OPG that cannot form homodimers yet is still detectable as elevated circulating immunoreactive OPG along with elevated soluble RANKL.\",\n      \"method\": \"TNFRSF11B sequencing, serum immunoreactive OPG and soluble RANKL ELISA measurement over 4 years\",\n      \"journal\": \"Journal of bone and mineral research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — ELISA measurement of circulating protein in a single patient; structural inference about dimerization from sequence analysis is consistent with prior in vitro data but not directly re-tested here\",\n      \"pmids\": [\"17352649\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The T allele of the C950T (rs2073617) promoter polymorphism in TNFRSF11B drives lower luciferase reporter expression in HeLa, COS-7, and RAW264.7 cell lines compared to the C allele, indicating a functional cis-regulatory effect on OPG transcription. Additionally, the C allele of rs4876869 causes exon skipping in a pre-mRNA splicing assay, reducing full-length OPG transcript.\",\n      \"method\": \"Promoter-luciferase reporter assay in three cell lines; exon-trapping splicing assay for rs4876869\",\n      \"journal\": \"Journal of molecular endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — two orthogonal functional assays (luciferase reporter + splicing assay) in multiple cell lines, single lab\",\n      \"pmids\": [\"21994215\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Human metastatic melanomas constitutively produce OPG (TNFRSF11B product) through a mechanism governed by membrane-bound TNF-α signaling through TNF receptor 1 (TNFR1), defining a specific regulatory axis controlling OPG production in tumor cells.\",\n      \"method\": \"Characterization of OPG production by melanoma cell lines; identification of membrane-bound TNF-α/TNFR1 signaling as the regulating mechanism\",\n      \"journal\": \"Pigment cell & melanoma research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — mechanistic pathway identification in cell lines, single lab, limited methodological detail in abstract\",\n      \"pmids\": [\"23490134\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"A heterozygous read-through mutation (c.1205A>T; p.Stop402Leu) in TNFRSF11B results in a gain-of-function OPG with enhanced capacity to inhibit osteoclastogenesis and bone resorption in a cell-based bone resorption assay, causing familial early-onset OA with chondrocalcinosis.\",\n      \"method\": \"Cell-based bone resorption assay comparing mutant vs. wild-type OPG; exome sequencing and linkage analysis for mutation identification\",\n      \"journal\": \"Annals of the rheumatic diseases\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — cell-based functional assay with clear wild-type vs. mutant comparison, single lab, limited to one assay type\",\n      \"pmids\": [\"24743232\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Circadian expression of Tnfrsf11b (OPG) in osteoblasts is regulated by the clock genes Bmal1 and REV-ERBα (Nr1d1): Bmal1 positively regulates rhythmic Tnfrsf11b expression and REV-ERBα negatively regulates it. α1B-adrenergic receptor signaling controls this circadian regulation, as genetic ablation of α1B-AR alters Tnfrsf11b expression concomitant with Bmal1 and Per2 in bone.\",\n      \"method\": \"Loss-of-function and gain-of-function experiments in MC3T3-E1 osteoblast cells; pharmacological stimulation with phenylephrine (α1-AR agonist); genetic ablation of α1B-AR in mice with in vivo bone expression analysis\",\n      \"journal\": \"Biology open\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal approaches (in vitro gain/loss-of-function, in vivo genetic ablation, pharmacological), single lab\",\n      \"pmids\": [\"26453621\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"TNFRSF11B is a direct target of miR-145 in chondrocytes, as confirmed by dual-luciferase reporter assay. miR-145 overexpression suppresses TNFRSF11B expression and inhibits chondrocyte proliferation and fibrosis; siRNA knockdown of TNFRSF11B phenocopies this inhibition.\",\n      \"method\": \"Dual-luciferase reporter assay for miR-145 targeting; miR-145 mimic transfection; siRNA knockdown of TNFRSF11B; MTT proliferation assay; Western blot for fibrosis markers\",\n      \"journal\": \"Molecular medicine reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — dual-luciferase assay validates direct targeting, with siRNA knockdown phenocopying mimic overexpression; single lab, two orthogonal methods\",\n      \"pmids\": [\"27922673\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TNFRSF11B (OPG) directly binds GSK-3β and upregulates its phosphorylation, leading to increased nuclear β-catenin and activation of Wnt/β-catenin downstream effectors in gastric cancer cells, promoting proliferation, migration, invasion, and inhibiting apoptosis.\",\n      \"method\": \"Co-immunoprecipitation (TNFRSF11B–GSK-3β interaction); immunofluorescence for nuclear β-catenin; Western blot for β-catenin and downstream effectors; in vitro and in vivo functional assays (proliferation, migration, invasion, apoptosis)\",\n      \"journal\": \"International journal of biological sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP for binding partner identification plus multiple functional readouts; single lab\",\n      \"pmids\": [\"32398963\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The OPG-XL (read-through/gain-of-function) mutation in TNFRSF11B is actually a loss-of-function mutation with respect to RANKL-mediated osteoclastogenesis: recombinant OPG-XL is less effective than wild-type OPG at blocking RANKL-induced osteoclastogenesis in monoculture and coculture models, and significantly less OPG-XL binds to osteoblastic cells. Effects on osteoclast survival and TRAIL-induced apoptosis were similar to wild-type OPG.\",\n      \"method\": \"In vitro RANKL-induced osteoclastogenesis in monoculture and coculture; osteoclast survival assay; TRAIL-induced apoptosis assay; ELISA and flow cytometry for OPG binding to MC3T3-E1 osteoblastic cells\",\n      \"journal\": \"Arthritis & rheumatology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple in vitro functional assays (osteoclastogenesis, survival, apoptosis, binding) with recombinant proteins, direct comparison of mutant vs. wild-type\",\n      \"pmids\": [\"33559312\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Overexpression of TNFRSF11B in primary human articular chondrocytes in a 3D in vitro chondrogenesis model strongly upregulates MMP13, COL2A1, COL1A1, and osteoblast markers RUNX2, ASPN, and OGN, and increases mineralization, suggesting OPG drives chondrocyte-to-osteoblast transition in OA. Notably, RANK and RANKL expression remained unchanged, indicating downstream pathways in cartilage independent of the OPG/RANK/RANKL triad.\",\n      \"method\": \"Lentiviral overexpression of TNFRSF11B in primary chondrocytes; 3D chondrogenic culture model; RT-qPCR; immunohistochemistry; ELISA; Alcian blue staining; RNA-seq correlation analysis\",\n      \"journal\": \"Rheumatology (Oxford, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (RT-qPCR, IHC, ELISA, histological staining) in a defined 3D functional model; single lab\",\n      \"pmids\": [\"33989379\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"TAp63 regulates bone remodeling by modulating the expression of TNFRSF11B/osteoprotegerin.\",\n      \"method\": \"Not fully detailed in abstract; implied transcriptional regulation study\",\n      \"journal\": \"Cell cycle\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — abstract is a stub with no experimental details provided; cannot assess methods or rigor\",\n      \"pmids\": [\"34763601\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TNFRSF11B promotes bladder cancer cell proliferation, migration, invasion, and EMT, and inhibits apoptosis via activation of the PI3K/AKT pathway; inhibition of PI3K/AKT with LY294002 reverses the effects of TNFRSF11B overexpression.\",\n      \"method\": \"siRNA knockdown and overexpression of TNFRSF11B in bladder cancer cells; Western blot for PI3K/AKT pathway markers and EMT markers; cell proliferation, migration, and invasion assays; apoptosis assay; in vivo tumor assay; LY294002 pharmacological inhibition\",\n      \"journal\": \"Molecular and cellular probes\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — pathway placement via pharmacological inhibitor rescue and multiple functional readouts; single lab, no reconstitution or structural data\",\n      \"pmids\": [\"39481664\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"TNFRSF11B overexpression in UCMSCs suppresses RANKL-induced osteoclast differentiation (via conditioned medium), but neither overexpression of TNFRSF11B nor treatment with exogenous OPG protein enhances osteogenic differentiation of UCMSCs in vitro. Proteomic analysis of conditioned medium from TNFRSF11B-overexpressing UCMSCs identified downregulation of C1R, MDH1, and ACLY and upregulation of FETUB and METRNL, associated with osteoclast inhibition.\",\n      \"method\": \"Lentiviral overexpression in UCMSCs; conditioned medium treatment of osteoclast precursors; ALP staining; TRAP staining; qRT-PCR; proteomic analysis\",\n      \"journal\": \"Journal of orthopaedic surgery and research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — multiple assays in a defined cell model with negative finding for osteogenesis clearly stated; single lab, single publication\",\n      \"pmids\": [\"40380204\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"CRISPR/Cas9 knock-in of the TNFRSF11B mutation (OPGmt) in mice produces osteopenia, elevated bone remodeling markers, increased osteoclast numbers and activity, and in female homozygous mice, osteoarthritis features (articular cartilage loss) by 12 months. Joints of OPGmt mice showed elevated pyrophosphate, TGF-β1, and ENPP1 activity — biomarkers of CPPD disease — establishing the mutation as a loss-of-function driving increased osteoclastogenesis and CPPD-related joint pathology.\",\n      \"method\": \"CRISPR/Cas9 knock-in murine model; histological scoring (Mankin); bone remodeling biomarkers; osteoclast number/activity assays; CPPD biomarker measurement (pyrophosphate, TGF-β1, ENPP1 activity) at 6 and 12 months\",\n      \"journal\": \"Annals of the rheumatic diseases\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — CRISPR/Cas9 knock-in model with multiple orthogonal in vivo phenotypic, histological, and biochemical readouts; recapitulates human disease features\",\n      \"pmids\": [\"41826214\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TNFRSF11B encodes osteoprotegerin (OPG), a soluble decoy receptor that binds RANKL via its cysteine-rich N-terminal domain and inhibits osteoclast differentiation and bone resorption; OPG forms homodimers via a C-terminal cysteine required for full activity, and loss-of-function mutations (deletions, cysteine-disrupting missense, truncations) abolish RANKL binding and/or dimerization causing uncontrolled osteoclastogenesis (juvenile Paget's disease), while a gain-of-function read-through mutation causes enhanced osteoclast inhibition leading to OA with chondrocalcinosis; in non-skeletal contexts OPG activates Wnt/β-catenin signaling in gastric cancer through direct binding and phosphorylation of GSK-3β, promotes bladder cancer via PI3K/AKT, is regulated transcriptionally by clock genes (Bmal1, REV-ERBα) downstream of α1B-adrenergic signaling in osteoblasts, is a direct miR-145 target in chondrocytes, and in OA cartilage drives chondrocyte-to-osteoblast transition independently of the RANKL/RANK axis.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TNFRSF11B encodes osteoprotegerin (OPG), a secreted decoy receptor that restrains osteoclast differentiation and bone resorption by sequestering RANKL, with its activity depending on an N-terminal cysteine-rich ligand-binding domain and C-terminal cysteine-mediated homodimerization [#0, #2]. Loss-of-function mutations operate through two convergent mechanisms: missense changes in the cysteine-rich domain disrupt RANKL binding with severity scaling to the degree of binding loss, while truncating/frameshift mutations remove the C-terminal cysteine, abolish homodimerization, and reduce RANKL-binding capacity, releasing osteoclastogenesis from inhibition [#1, #2, #3]. A knock-in murine model recapitulates this, producing osteopenia, elevated bone remodeling, increased osteoclast activity, and CPPD-associated joint pathology [#15]. A read-through allele (OPG-XL), once classified as gain-of-function, behaves as loss-of-function for RANKL-mediated osteoclastogenesis with reduced binding to osteoblastic cells [#6, #10]. OPG expression is controlled at multiple levels — by functional promoter and splicing polymorphisms [#4], by circadian clock genes Bmal1 and REV-ERBα downstream of α1B-adrenergic signaling in osteoblasts [#7], and by miR-145 in chondrocytes [#8]. Beyond the skeletal RANKL axis, OPG drives a chondrocyte-to-osteoblast transition in articular cartilage independently of RANK/RANKL [#11], and in tumors it activates Wnt/β-catenin signaling via direct binding and phosphorylation of GSK-3β in gastric cancer [#9] and the PI3K/AKT pathway in bladder cancer [#13].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established that disease-associated TNFRSF11B mutations act by abolishing OPG's functional ability to suppress bone resorption, defining the gene's loss-of-function mechanism.\",\n      \"evidence\": \"Recombinant wild-type vs. mutant OPG from HEK conditioned medium in an in vitro bone resorption assay\",\n      \"pmids\": [\"12189164\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve whether the defect was in RANKL binding, dimerization, or secretion\", \"Single mutation tested\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Resolved a genotype-phenotype correlation by linking mutation location within the cysteine-rich ligand-binding domain to severity of RANKL-binding disruption.\",\n      \"evidence\": \"Mutation analysis across affected families with structural prediction correlated to clinical severity\",\n      \"pmids\": [\"14672344\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional effects predicted, not directly measured by binding assay\", \"No structural model verified\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Demonstrated that C-terminal truncation abolishes OPG homodimerization and reduces RANKL binding, mechanistically tying dimerization to full activity.\",\n      \"evidence\": \"Transient overexpression with Western blot for dimerization and ELISA for RANKL binding\",\n      \"pmids\": [\"15777670\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not quantify residual monomer activity in vivo\", \"Single truncating allele\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Showed a frameshift removing the dimerization cysteine yields monomeric OPG yet still elevated circulating immunoreactive protein, clarifying that immunoassay levels do not reflect functional activity.\",\n      \"evidence\": \"Sequencing plus longitudinal serum OPG and soluble RANKL ELISA in a patient\",\n      \"pmids\": [\"17352649\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Dimerization inferred from sequence, not re-tested directly\", \"Single patient\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identified functional cis-regulatory variants controlling OPG transcription and splicing, extending genetic risk beyond coding mutations.\",\n      \"evidence\": \"Promoter-luciferase reporter in three cell lines and an exon-trapping splicing assay\",\n      \"pmids\": [\"21994215\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Effect on endogenous OPG protein levels in bone not measured\", \"Trans-acting factors driving promoter activity unidentified\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defined an upstream regulatory axis for OPG production in tumor cells, implicating membrane-bound TNF-α/TNFR1 signaling.\",\n      \"evidence\": \"Characterization of OPG production in melanoma cell lines with pathway dissection\",\n      \"pmids\": [\"23490134\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Limited methodological detail\", \"Functional consequence of tumor OPG not established here\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Initially characterized a read-through allele as gain-of-function with enhanced osteoclastogenesis inhibition causing early-onset OA with chondrocalcinosis.\",\n      \"evidence\": \"Cell-based bone resorption assay comparing mutant vs. wild-type OPG, with exome sequencing and linkage\",\n      \"pmids\": [\"24743232\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single assay type\", \"Mechanism linking enhanced inhibition to chondrocalcinosis unexplained\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Placed OPG transcription under circadian control, linking α1B-adrenergic signaling and clock genes to rhythmic bone gene expression.\",\n      \"evidence\": \"Gain/loss-of-function in MC3T3-E1 cells, phenylephrine stimulation, and α1B-AR knockout mice\",\n      \"pmids\": [\"26453621\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct promoter occupancy by Bmal1/REV-ERBα not shown\", \"Physiological consequence for bone mass not quantified\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identified miR-145 as a direct post-transcriptional repressor of TNFRSF11B in chondrocytes affecting proliferation and fibrosis.\",\n      \"evidence\": \"Dual-luciferase reporter, miR-145 mimic, and TNFRSF11B siRNA phenocopy in chondrocytes\",\n      \"pmids\": [\"27922673\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo relevance not established\", \"Single cell type\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Revealed a non-canonical, RANKL-independent OPG function: direct binding and phosphorylation of GSK-3β to activate Wnt/β-catenin signaling in gastric cancer.\",\n      \"evidence\": \"Co-IP of OPG–GSK-3β, immunofluorescence for nuclear β-catenin, and functional cancer assays\",\n      \"pmids\": [\"32398963\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single Co-IP without reciprocal/structural validation\", \"How a secreted decoy accesses cytoplasmic GSK-3β unresolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Reclassified the OPG-XL read-through allele as loss-of-function for RANKL-mediated osteoclastogenesis with reduced binding to osteoblastic cells, overturning the earlier gain-of-function model.\",\n      \"evidence\": \"Recombinant OPG-XL vs. wild-type in osteoclastogenesis monoculture/coculture, survival, apoptosis, and binding assays\",\n      \"pmids\": [\"33559312\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism connecting reduced binding to chondrocalcinosis phenotype unresolved\", \"Effect on TRAIL/survival unchanged, leaving disease driver partly open\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrated OPG drives chondrocyte-to-osteoblast transition in articular cartilage through pathways independent of the RANK/RANKL triad.\",\n      \"evidence\": \"Lentiviral TNFRSF11B overexpression in primary chondrocytes in a 3D chondrogenesis model with RT-qPCR, IHC, and mineralization assays\",\n      \"pmids\": [\"33989379\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream effector pathway in cartilage not identified\", \"Receptor/binding partner mediating the effect unknown\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Implicated TAp63 as a transcriptional regulator of TNFRSF11B in bone remodeling.\",\n      \"evidence\": \"Implied transcriptional regulation study (abstract stub)\",\n      \"pmids\": [\"34763601\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No experimental detail available to assess rigor\", \"Direct promoter binding not demonstrated\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Placed OPG's pro-tumor activity in bladder cancer downstream of PI3K/AKT signaling via inhibitor rescue.\",\n      \"evidence\": \"Knockdown/overexpression in bladder cancer cells with LY294002 rescue, EMT markers, and in vivo tumor assay\",\n      \"pmids\": [\"39481664\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct binding partner for pathway activation identified\", \"Single lab, no structural data\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Showed OPG overexpression suppresses osteoclastogenesis but does not promote osteogenesis, and identified secreted proteomic mediators associated with osteoclast inhibition.\",\n      \"evidence\": \"Lentiviral overexpression in UCMSCs, conditioned medium osteoclast/osteogenic assays, and conditioned-medium proteomics\",\n      \"pmids\": [\"40380204\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal role of identified proteins (C1R, FETUB, METRNL) not tested\", \"Single cell model\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Provided in vivo causal confirmation that the TNFRSF11B mutation is loss-of-function, driving osteopenia, increased osteoclastogenesis, and CPPD-related joint pathology.\",\n      \"evidence\": \"CRISPR/Cas9 knock-in mouse with histology, bone remodeling and osteoclast assays, and CPPD biomarker measurement\",\n      \"pmids\": [\"41826214\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular link from OPG loss to pyrophosphate/ENPP1 elevation not fully resolved\", \"Sex-specific OA penetrance unexplained\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The receptor and downstream effector pathway mediating OPG's RANKL-independent actions in cartilage and tumors remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No cell-surface receptor for non-canonical OPG signaling identified\", \"Structural basis for OPG–GSK-3β interaction unknown\", \"Reconciliation of decoy versus signaling roles incomplete\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 2, 10]},\n      {\"term_id\": \"GO:0140313\", \"supporting_discovery_ids\": [2, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [0, 15]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [9, 13]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [15, 9, 13]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"RANKL\", \"GSK-3\\u03b2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":6,"faith_pct":83.33333333333333}}