{"gene":"TCIRG1","run_date":"2026-04-28T21:42:58","timeline":{"discoveries":[{"year":2000,"finding":"TCIRG1 encodes the osteoclast-specific 116-kDa subunit (a3) of the vacuolar proton pump (V-ATPase), and loss-of-function mutations in TCIRG1 cause autosomal recessive osteopetrosis by impairing osteoclast function (not differentiation), establishing TCIRG1 as essential for mature osteoclast resorptive activity.","method":"Mutation analysis in osteopetrosis patients; functional correlation with osteoclast presence/absence","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 2 — foundational disease-gene identification, replicated across multiple patient cohorts and confirmed by mouse knockout","pmids":["10888887"],"is_preprint":false},{"year":1999,"finding":"Targeted disruption of Atp6i (mouse ortholog of TCIRG1) results in severe osteopetrosis; Atp6i-/- osteoclasts lose extracellular acidification function but retain intracellular lysosomal proton pump activity, demonstrating that the a3 subunit is specifically required for plasma membrane-directed extracellular acidification by osteoclasts.","method":"Gene knockout mouse model; pH measurement in lysosomes; proton transport assay in kidney microsomes; acid-base balance measurement","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 1 — knockout model with multiple orthogonal functional assays, foundational mechanistic study","pmids":["10581033"],"is_preprint":false},{"year":2004,"finding":"In vitro-differentiated osteoclasts from patients with TCIRG1 compound heterozygous mutations can fuse and attach to bone but fail to acidify the resorption compartment, consistent with TCIRG1 being essential for H+-ATPase assembly at the ruffled border; by contrast, CLCN7 defects impair organic matrix removal rather than acidification.","method":"CD14+ monocyte differentiation into osteoclasts; acid secretion assay; bone pit assay; genotype correlation","journal":"Journal of bone and mineral research","confidence":"High","confidence_rationale":"Tier 2 — direct functional assays in patient-derived cells with genotype-phenotype correlation","pmids":["15231021"],"is_preprint":false},{"year":2004,"finding":"TCIRG1 (ATP6i/a3) mutations cause osteopetrosis with osteoclasts that are morphologically normal (normal actin rings, clear zones, podosomes, αVβ3, c-Src, PYK2) but excavate only faint, shallow pits, confirming the specific role of the a3 subunit in bone acidification rather than osteoclast cytoskeletal organization.","method":"Bone biopsy histology; in vitro osteoclast differentiation from patient CD14+ cells; TRAP activity; bone resorption pit assay; immunostaining","journal":"The American journal of pathology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods in patient-derived cells, confirms functional specificity","pmids":["12507890"],"is_preprint":false},{"year":2003,"finding":"Post-transplant osteoclasts in TCIRG1-deficient patients rescue a3 subunit immunoreactivity, demonstrating that donor-derived osteoclasts restore V-ATPase a3 expression and function, confirming the cell-autonomous nature of the TCIRG1 defect.","method":"Bone marrow transplantation with post-transplant immunostaining for a3 subunit","journal":"The American journal of pathology","confidence":"Medium","confidence_rationale":"Tier 2 — direct rescue experiment, single study","pmids":["12507890"],"is_preprint":false},{"year":1999,"finding":"TCIRG1/TIRC7 are alternative transcripts of the same gene located on chromosome 11q13.4-q13.5; TIRC7 (TV2, 7-transmembrane domain isoform) is expressed in alloactivated T lymphocytes while OC116 (TV1) is the osteoclast-specific V-ATPase subunit, establishing tissue-specific alternative splicing of the locus.","method":"Genomic organization analysis; RT-PCR in human T lymphocytes; exon-intron mapping","journal":"Genomics","confidence":"Medium","confidence_rationale":"Tier 2 — direct molecular characterization of transcript variants","pmids":["10329006"],"is_preprint":false},{"year":1998,"finding":"TIRC7 (the T-cell isoform of TCIRG1) functions as a membrane protein essential for T cell activation; anti-TIRC7 antibodies inhibit human T cell proliferation and IL-2 secretion in vitro, and specifically suppress IFN-γ (Th1) but not IL-4 (Th2) expression; cross-reactive antibody prolonged rat kidney allograft survival in vivo.","method":"In vitro T cell proliferation assay; cytokine ELISA; rat kidney allograft model with anti-TIRC7 antibody treatment","journal":"Immunity","confidence":"Medium","confidence_rationale":"Tier 2 — functional inhibition experiments in vitro and in vivo, single lab","pmids":["9806637"],"is_preprint":false},{"year":2004,"finding":"TIRC7-deficient mice exhibit increased T and B cell proliferation and cytokine production (IL-2, IFN-γ, IL-4), reduced CTLA-4 expression on activated T cells, expanded memory/effector T cells (CD62L↓, CD11a↑, CD44↑), B cell hyperreactivity, and augmented delayed-type hypersensitivity, establishing TIRC7 as a negative regulator of lymphocyte activation.","method":"Gene-targeted TIRC7 knockout mice; in vitro T and B cell proliferation assays; cytokine measurement; flow cytometry; delayed-type hypersensitivity assay","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 — genetic knockout with multiple orthogonal readouts, strong evidence for regulatory role","pmids":["15294947"],"is_preprint":false},{"year":2006,"finding":"Anti-TIRC7 antibody induces early surface expression of CTLA-4; TIRC7 and CTLA-4 colocalize in T cells and both associate with clathrin-coated vesicles sharing intracellular transport systems; TIRC7-mediated inhibition of T cell proliferation is abolished by CTLA-4 blockade or in CTLA-4-deficient mouse splenocytes, placing TIRC7 upstream of CTLA-4 in the T cell inhibitory pathway.","method":"Immunofluorescence colocalization; flow cytometry; CTLA-4 antibody blockade; CTLA-4 knockout splenocyte experiments; transcription activation assay","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 — epistasis established by multiple methods including knockout rescue, mechanistic pathway defined","pmids":["17082597"],"is_preprint":false},{"year":2008,"finding":"HLA-DR alpha 2 domain directly binds TIRC7 on lymphocytes, delivering negative signals that inhibit proliferation and induce apoptosis in CD4+ and CD8+ T cells via the intrinsic apoptotic pathway; this interaction recruits SHP-1 to TIRC7, decreases phosphorylation of STAT4, TCR-zeta chain and ZAP70, and inhibits IFN-γ and FasL expression; HLA-DRα2 and TIRC7 co-localize at the APC–T cell interaction site.","method":"Pulldown/co-localization; SHP-1 recruitment assay; phosphorylation assays; apoptosis assay; in vivo LPS model","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 1-2 — binding partner identified, downstream signaling cascade characterized with multiple orthogonal methods","pmids":["18270567"],"is_preprint":false},{"year":2010,"finding":"In Tcirg1-/- mice, the a3 subunit accumulates in choriocapillary meshwork of uveal tissues; loss of a3 leads to narrowed skull foramina causing optic nerve compression and increased retinal apoptosis; compensatory upregulation of the a4 V-ATPase subunit isoform occurs in mutant choriocapillary meshwork, revealing isoform compensation among V-ATPase a-subunits.","method":"X-ray microtomography; immunohistochemistry for V-ATPase subunit isoforms; apoptosis assay in retina; Tcirg1-/- mouse model","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization and functional consequence demonstrated in knockout model","pmids":["20711468"],"is_preprint":false},{"year":2012,"finding":"Tcirg1 (a3 subunit) is not detectably expressed in mouse maturation-stage ameloblasts despite their use of V-ATPase; Tcirg1-null mice have normal enamel formation and mineral content, demonstrating that the osteoclast-type plasma membrane proton pump using the a3 subunit is not required for ameloblast enamel acidification.","method":"Immunohistochemistry; mineral content analysis; Tcirg1 null mouse model analysis","journal":"Bone","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization with functional consequence in knockout model","pmids":["22245629"],"is_preprint":false},{"year":2013,"finding":"Lentiviral gene transfer of TCIRG1 cDNA into peripheral blood CD34+ cells from infantile malignant osteopetrosis patients restores osteoclast bone resorption to ~70-80% of normal, as measured by Ca2+ release, CTX-I bone degradation product, and resorption pit formation, demonstrating that re-expression of TCIRG1 is sufficient to restore V-ATPase-dependent osteoclast function.","method":"Lentiviral transduction; qPCR; Western blot; Ca2+ release assay; CTX-I ELISA; bone resorption pit assay; NSG mouse engraftment","journal":"Bone","confidence":"High","confidence_rationale":"Tier 2 — functional rescue by gene complementation with multiple orthogonal readouts","pmids":["23907031"],"is_preprint":false},{"year":2013,"finding":"AAV-mediated RNAi knockdown of Atp6i/TCIRG1 in periodontal tissues impairs osteoclast extracellular acidification and bone resorption, and also reduces T-cell infiltration and inflammatory cytokine expression; Atp6i+/- haploinsufficient mice are similarly protected from P. gingivalis-induced bone loss and gingival inflammation, establishing a dual role for Atp6i in bone resorption and tissue inflammation.","method":"AAV-shRNA delivery in vivo; bone resorption quantification; T-cell number measurement; cytokine gene expression; Atp6i+/- haploinsufficiency model","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo loss-of-function with multiple readouts, confirmed by haploinsufficiency model","pmids":["23577057"],"is_preprint":false},{"year":2014,"finding":"TCIRG1 mutations (but not CLCN7 or TNFRSF11A mutations) are specifically associated with severe osteoid accumulation and decreased calcium content in bone matrix (osteomalacia), demonstrating that loss of V-ATPase a3 specifically impairs bone matrix mineralization in addition to bone resorption.","method":"Undecalcified iliac crest biopsy histology; calcium content analysis; genotype-phenotype comparison across osteopetrosis subtypes","journal":"Journal of bone and mineral research","confidence":"High","confidence_rationale":"Tier 2 — direct genotype-phenotype correlation with histological evidence across multiple patients and subtypes","pmids":["24108692"],"is_preprint":false},{"year":2016,"finding":"TCIRG1 protein expression from a bicistronic lentiviral vector is post-transcriptionally regulated: protein accumulates only in mature osteoclasts, not in precursors or macrophages, preventing ectopic overexpression; codon optimization increased mRNA but paradoxically lowered protein and functional rescue, revealing post-transcriptional control of TCIRG1 expression.","method":"Lentiviral vector expression analysis; flow cytometry; Western blot at different differentiation stages; codon optimization comparison; bone resorption assay","journal":"Calcified tissue international","confidence":"Medium","confidence_rationale":"Tier 2 — direct mechanistic finding on post-transcriptional regulation, single lab","pmids":["27541021"],"is_preprint":false},{"year":2019,"finding":"Transgenic TCIRG1 expression in iPSC-derived osteoclasts from an infantile malignant osteopetrosis patient restores cathepsin K (CTSK) and TRAP expression and rescues pit formation, establishing that TCIRG1 function is required for downstream expression of bone remodeling enzymes in addition to proton pumping.","method":"iPSC generation from patient fibroblasts; osteoclast differentiation; transgenic TCIRG1 rescue; qPCR for CTSK/TRAP; pit formation assay","journal":"The Journal of bone and joint surgery. American volume","confidence":"Medium","confidence_rationale":"Tier 2 — genetic rescue experiment with multiple functional readouts, single lab","pmids":["31567691"],"is_preprint":false},{"year":2020,"finding":"Knockdown of Tcirg1 in mouse bone marrow-derived monocytes inhibits formation of large osteoclasts (>100 μm) by decreasing NFATc1 and IP3R2 expression; reduced IP3R2 lowers intracellular calcium levels, which limits nuclear translocation of NFATc1 during RANKL-induced osteoclastogenesis.","method":"Lentiviral shRNA knockdown; osteoclast size quantification; NFATc1 and IP3R2 expression assay; intracellular calcium measurement; nuclear translocation assay","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — mechanistic pathway defined with multiple readouts, single lab","pmids":["32790690"],"is_preprint":false},{"year":2012,"finding":"A peptide corresponding to the C-terminus of Tirc7 (the T-cell isoform of Atp6v0a3/TCIRG1) induces differentiation of RAW264.7 cells and bone marrow CD11b+ cells into TRAP-positive multinucleated osteoclast-like cells and stimulates an autocrine/paracrine regulatory loop, revealing that the extracellular C-terminus of Tirc7 directly signals to osteoclast precursor cells.","method":"Molecular cloning of Tirc7 C-terminal peptide; treatment of RAW264.7, CD11b+ cells, and primary monocytes; TRAP staining; multinucleation assay; F4/80 immunostaining","journal":"Journal of cellular physiology","confidence":"Medium","confidence_rationale":"Tier 3 — single lab, peptide gain-of-function approach with multiple cell type readouts","pmids":["22015593"],"is_preprint":false},{"year":2023,"finding":"In Atp6i-/- mice, osteoclast dysfunction prevents TGF-β1 release from alveolar bone matrix, impairing TGF-β1/Smad2/3 signaling in radicular odontoblasts and arresting tooth root formation; ectopic TGF-β1 partially rescues root development in Atp6i-/- tooth germ transplants, placing Atp6i-dependent bone resorption upstream of TGF-β1 release required for odontoblast differentiation.","method":"Atp6i-/- mouse model; RNA-seq; qPCR for odontoblast markers; Smad2/3 phosphorylation assay; anti-TGF-β1 neutralization; conditioned medium experiments; kidney capsule transplantation rescue","journal":"International journal of oral science","confidence":"Medium","confidence_rationale":"Tier 2 — epistasis established with multiple orthogonal methods and rescue experiment, single lab","pmids":["37599332"],"is_preprint":false},{"year":2025,"finding":"TCIRG1 deficiency in knockout mice delays osteoarthritis progression; in vitro, Tcirg1 knockdown in osteoclasts inhibits cell fusion and bone resorption by impairing lysosome acidification and peripheral lysosome accumulation, establishing a role for the a3 subunit in lysosomal trafficking to the cell periphery during osteoclast activation.","method":"Tcirg1-knockout OA mouse model (DMM surgery); histology; micro-CT; in vitro osteoclast differentiation with shRNA knockdown; lysosome acidification and distribution assays","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo knockout model plus in vitro mechanistic assays, single study","pmids":["40995561"],"is_preprint":false},{"year":2025,"finding":"iPSCs from congenital neutropenia patients bearing heterozygous TCIRG1 mutations (R736C, R736S, R736P, E722D) show defects in myeloid differentiation and increased cell death; CRISPR/Cas9 correction of R736C restores normal neutrophil differentiation; mutant TCIRG1 protein shows reduced expression and a more diffuse cytosolic distribution instead of normal vesicular/V-ATPase localization.","method":"iPSC generation; in vitro hematopoietic differentiation; CRISPR/Cas9 correction; immunofluorescence for TCIRG1 localization; neutrophil differentiation assay","journal":"Journal of cellular immunology","confidence":"Medium","confidence_rationale":"Tier 2 — CRISPR genetic rescue confirms pathogenicity, localization defect identified, single study","pmids":["40964614"],"is_preprint":false},{"year":2024,"finding":"VMA21 stabilizes TCIRG1 protein by binding to it and inhibiting its ubiquitination-dependent degradation in triple-negative breast cancer cells, establishing VMA21 as a regulator of TCIRG1 protein stability through the ubiquitin-proteasome pathway.","method":"Immunoprecipitation; ubiquitination assay; VMA21 knockdown with TCIRG1 protein level measurement","journal":"American journal of cancer research","confidence":"Low","confidence_rationale":"Tier 3 — single Co-IP/ubiquitination assay in cancer cell line context, not validated in osteoclast biology","pmids":["39267677"],"is_preprint":false},{"year":2004,"finding":"Splicing mutations in TCIRG1 flanking splice sites (c.117+4A>T, c.1673+5G>A, c.504-8G>A) cause aberrant mRNA processing demonstrated in hybrid minigene assays; complementary U1 snRNA corrects the c.117+4A>T 5' splice site defect but not the c.1673+5G>A mutation, revealing mechanistic differences between mutations near invariant GT donor sites and those further from splice junctions.","method":"Hybrid minigene splicing assay; U1 snRNA cotransfection rescue experiments","journal":"Human mutation","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro reconstitution of splicing defect and mechanistic rescue, single lab","pmids":["15300850"],"is_preprint":false},{"year":2019,"finding":"The TCIRG1 c.G630A mutation causes exons 5-6 skipping (ΔE56); the ΔE56 truncated protein lacking part of the cytoplasmic N-terminal domain fails to support V-ATPase-mediated vacuolar acidification in yeast (Vph1p ortholog growth assay on Zn2+-containing plates), demonstrating that exons 5-6 encode a functionally essential domain for V-ATPase activity.","method":"RT-PCR splicing analysis; yeast complementation assay (Vph1p); osteoclast differentiation and bone resorption assay; TCIRG1 Western blot","journal":"Journal of cellular biochemistry","confidence":"Medium","confidence_rationale":"Tier 1-2 — yeast functional assay plus patient osteoclast phenotype, single lab","pmids":["31111556"],"is_preprint":false}],"current_model":"TCIRG1 encodes the a3 subunit (OC-116) of the vacuolar H+-ATPase (V-ATPase), which is essential for osteoclast-mediated extracellular acidification at the ruffled border: the protein is required for plasma membrane-directed proton pumping to dissolve bone mineral, for lysosome acidification and peripheral trafficking during bone resorption, and for downstream expression of bone remodeling enzymes (cathepsin K, TRAP); an alternative transcript (TIRC7) functions as a T-cell co-inhibitory receptor that acts upstream of CTLA-4 through HLA-DRα2 binding, SHP-1 recruitment, and inhibition of TCR-proximal signaling, while its protein stability is regulated by VMA21-mediated protection from ubiquitin-dependent degradation."},"narrative":{"teleology":[{"year":1998,"claim":"Whether the TIRC7 gene product had any functional role in T cells was unknown; antibody-blocking experiments revealed that TIRC7 is a membrane protein required for T cell proliferation, IL-2 secretion, and Th1-skewed cytokine production, and that anti-TIRC7 antibody prolongs allograft survival, establishing the first evidence of an immune-regulatory function at this locus.","evidence":"In vitro T cell proliferation/cytokine assays and rat kidney allograft model with anti-TIRC7 antibody","pmids":["9806637"],"confidence":"Medium","gaps":["Single lab; mechanism of TIRC7 signaling undefined","Relationship between TIRC7 and the osteoclast isoform not yet clarified"]},{"year":1999,"claim":"The molecular identity of the osteoclast-specific V-ATPase a-subunit and its relationship to TIRC7 were unresolved; genomic analysis demonstrated that TCIRG1 and TIRC7 are alternative transcripts of the same gene at 11q13, with the osteoclast isoform (OC116/TV1) and the T-cell isoform (TV2) arising from tissue-specific alternative splicing, and knockout of the mouse ortholog Atp6i caused severe osteopetrosis with loss of extracellular but not lysosomal acidification.","evidence":"Genomic exon-intron mapping; RT-PCR; Atp6i knockout mice with pH and proton transport assays","pmids":["10329006","10581033"],"confidence":"High","gaps":["Whether a3 loss affects V-ATPase assembly versus membrane targeting unclear","Mechanism of isoform-specific plasma membrane versus lysosome localization not defined"]},{"year":2000,"claim":"Whether human osteopetrosis was caused by TCIRG1 mutations was unknown; mutation analysis across patient cohorts identified loss-of-function TCIRG1 mutations as the most common cause of autosomal recessive osteopetrosis, confirming that osteoclasts are present but functionally impaired.","evidence":"Mutation screening in osteopetrosis patient cohorts with genotype-phenotype correlation","pmids":["10888887"],"confidence":"High","gaps":["Molecular basis of individual mutations not characterized","Whether haploinsufficiency causes disease unclear"]},{"year":2004,"claim":"Whether TCIRG1-deficient osteoclasts had broader cytoskeletal or differentiation defects was unknown; detailed phenotyping showed that mutant osteoclasts form normal actin rings, clear zones, and podosomes but specifically fail to acidify the resorption compartment, while bone marrow transplant rescued a3 expression, confirming a cell-autonomous acidification defect.","evidence":"Patient-derived osteoclast differentiation, resorption pit assays, immunostaining for cytoskeletal markers, post-transplant biopsy immunohistochemistry","pmids":["12507890","15231021"],"confidence":"High","gaps":["Whether mutant V-ATPase complexes assemble but mislocalize versus fail to assemble not resolved","Effect on osteoclast secretory pathway not examined"]},{"year":2004,"claim":"Whether TIRC7 was necessary for immune homeostasis in vivo was unresolved; TIRC7-knockout mice showed hyperproliferation of T and B cells, augmented cytokine production, reduced CTLA-4 expression, and enhanced delayed-type hypersensitivity, establishing TIRC7 as a non-redundant negative regulator of lymphocyte activation.","evidence":"Gene-targeted TIRC7 knockout mice; proliferation assays; flow cytometry; DTH assay","pmids":["15294947"],"confidence":"High","gaps":["Signaling pathway downstream of TIRC7 not yet defined","Whether the T-cell phenotype contributes to osteopetrosis pathology unknown"]},{"year":2006,"claim":"How TIRC7 inhibits T cell activation mechanistically was unknown; epistasis experiments showed that TIRC7 promotes early CTLA-4 surface expression, the two proteins colocalize in clathrin-coated vesicles, and TIRC7-mediated inhibition requires intact CTLA-4, placing TIRC7 upstream of CTLA-4 in the co-inhibitory pathway.","evidence":"Immunofluorescence colocalization; CTLA-4 antibody blockade; CTLA-4-deficient splenocyte experiments","pmids":["17082597"],"confidence":"High","gaps":["Direct physical interaction between TIRC7 and CTLA-4 not demonstrated","Molecular basis of CTLA-4 mobilization by TIRC7 unclear"]},{"year":2008,"claim":"The ligand for TIRC7 and its proximal signaling events were unknown; HLA-DRα2 was identified as a direct binding partner that delivers negative signals recruiting SHP-1, suppressing phosphorylation of ZAP70, TCR-ζ, and STAT4, and inducing apoptosis via the intrinsic pathway.","evidence":"Pulldown, co-localization at APC–T cell contacts, SHP-1 recruitment assay, phospho-signaling assays, apoptosis assay","pmids":["18270567"],"confidence":"High","gaps":["Structure of the TIRC7–HLA-DRα2 interface unresolved","Whether SHP-1 directly dephosphorylates TCR-ζ/ZAP70 or acts indirectly not tested"]},{"year":2013,"claim":"Whether TCIRG1 gene transfer could functionally correct patient osteoclasts was untested; lentiviral delivery of TCIRG1 cDNA into patient CD34⁺ cells restored bone resorption to 70–80% of normal, establishing proof-of-concept for gene therapy of TCIRG1-dependent osteopetrosis.","evidence":"Lentiviral transduction of patient CD34⁺ cells; Ca²⁺ release, CTX-I ELISA, pit assay; NSG mouse engraftment","pmids":["23907031"],"confidence":"High","gaps":["Long-term in vivo engraftment and correction not demonstrated","Optimal vector design for clinical translation undefined"]},{"year":2014,"claim":"Whether TCIRG1 loss affected bone matrix quality beyond resorption was unknown; genotype-specific histological analysis revealed that TCIRG1 mutations uniquely cause severe osteoid accumulation and decreased calcium content (osteomalacia), separating this from CLCN7 or TNFRSF11A mutation phenotypes.","evidence":"Undecalcified iliac crest biopsy histology and calcium content analysis across genotyped osteopetrosis subtypes","pmids":["24108692"],"confidence":"High","gaps":["Whether the mineralization defect is secondary to impaired acidification or an independent function of a3 unknown"]},{"year":2019,"claim":"How TCIRG1 expression is controlled at the protein level was unclear; studies revealed that TCIRG1 protein accumulates only in mature osteoclasts despite constitutive mRNA expression, and that specific exon-encoded domains (exons 5–6) are essential for V-ATPase function as demonstrated by yeast complementation.","evidence":"Lentiviral vector expression at different differentiation stages; codon optimization analysis; yeast Vph1p complementation assay","pmids":["27541021","31111556"],"confidence":"Medium","gaps":["Identity of factors controlling post-transcriptional regulation unknown","Structure–function mapping of the N-terminal cytoplasmic domain incomplete"]},{"year":2020,"claim":"Whether TCIRG1 influences osteoclast fusion and differentiation signaling beyond its proton-pumping role was unresolved; knockdown revealed that Tcirg1 promotes large osteoclast formation by sustaining IP3R2 expression and intracellular calcium levels required for NFATc1 nuclear translocation during RANKL-induced osteoclastogenesis.","evidence":"Lentiviral shRNA knockdown in bone marrow monocytes; NFATc1/IP3R2 expression; calcium imaging; nuclear translocation assay","pmids":["32790690"],"confidence":"Medium","gaps":["Whether IP3R2 regulation is direct or secondary to acidification defect not tested","Single lab, not independently confirmed"]},{"year":2023,"claim":"Whether osteoclast dysfunction from Tcirg1 loss impacts neighboring non-osteoclast cell types was unknown; in Atp6i⁻/⁻ mice, failure to release TGF-β1 from bone matrix impaired Smad2/3 signaling in odontoblasts, arresting tooth root formation, and ectopic TGF-β1 partially rescued the phenotype, placing Tcirg1-dependent resorption upstream of paracrine growth factor signaling.","evidence":"Atp6i⁻/⁻ mouse; RNA-seq; Smad2/3 phosphorylation; TGF-β1 neutralization; kidney capsule transplant rescue","pmids":["37599332"],"confidence":"Medium","gaps":["Whether other resorption-released growth factors are similarly affected not examined","Relevance to human dental phenotype not confirmed"]},{"year":2025,"claim":"Whether TCIRG1 controls lysosomal positioning during osteoclast activation and whether heterozygous mutations affect myeloid lineage beyond osteoclasts were open questions; new studies showed that Tcirg1 loss impairs lysosome acidification and peripheral lysosome accumulation during resorption, and that heterozygous TCIRG1 missense mutations cause congenital neutropenia correctable by CRISPR repair.","evidence":"Tcirg1-KO OA mouse model with lysosome distribution assays; iPSC-derived neutrophil differentiation with CRISPR/Cas9 correction of R736C","pmids":["40995561","40964614"],"confidence":"Medium","gaps":["Mechanism linking a3 to peripheral lysosome trafficking not defined","Whether heterozygous mutations cause neutropenia via V-ATPase assembly defects versus dominant-negative effects unclear"]},{"year":null,"claim":"The structural basis of a3-subunit integration into V₀ and its isoform-specific targeting to ruffled border versus lysosomes remains undefined; the molecular mechanism by which TIRC7 mobilizes CTLA-4 to the cell surface and the physiological interplay between the osteoclast and T-cell isoforms in vivo have not been resolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of human a3 in the V₀ complex","Mechanism of isoform-specific membrane targeting unresolved","Whether TIRC7 immune function contributes to osteopetrosis clinical phenotype unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[1,2,3,12]},{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[1,2,12]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[7,8,9]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,2,3]},{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[20]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[8,21]}],"pathway":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[1]},{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[1,2,12]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[7,8,9]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[19]}],"complexes":["V-ATPase (V₀ sector)"],"partners":["VMA21","CTLA4","HLA-DRA","PTPN6","NFATC1"],"other_free_text":[]},"mechanistic_narrative":"TCIRG1 encodes the a3 subunit of the vacuolar H⁺-ATPase (V-ATPase), a proton pump component that is essential for osteoclast-mediated extracellular acidification at the ruffled border and for lysosomal acidification and peripheral trafficking during bone resorption [PMID:10581033, PMID:15231021, PMID:40995561]. Loss-of-function mutations cause autosomal recessive infantile malignant osteopetrosis: TCIRG1-deficient osteoclasts differentiate and polarize normally but fail to acidify the resorption lacuna, and re-expression by lentiviral gene transfer rescues bone resorption to near-normal levels [PMID:10888887, PMID:12507890, PMID:23907031]. An alternative transcript (TIRC7) produces a T-cell co-inhibitory receptor that binds HLA-DRα2, recruits SHP-1, suppresses TCR-proximal signaling (ZAP70, TCR-ζ, STAT4 phosphorylation), and acts upstream of CTLA-4 surface expression to limit lymphocyte activation [PMID:9806637, PMID:15294947, PMID:17082597, PMID:18270567]. TCIRG1 also influences osteoclast fusion through an IP3R2–NFATc1 calcium-signaling axis, promotes downstream expression of bone-remodeling enzymes cathepsin K and TRAP, and its protein stability is regulated by VMA21-mediated protection from ubiquitin-dependent degradation [PMID:32790690, PMID:31567691, PMID:39267677]."},"prefetch_data":{"uniprot":{"accession":"Q13488","full_name":"V-type proton ATPase 116 kDa subunit a 3","aliases":["Osteoclastic proton pump 116 kDa subunit","OC-116 kDa","OC116","T-cell immune regulator 1","T-cell immune response cDNA7 protein","TIRC7","Vacuolar proton translocating ATPase 116 kDa subunit a isoform 3"],"length_aa":830,"mass_kda":93.0,"function":"Subunit of the V0 complex of vacuolar(H+)-ATPase (V-ATPase), a multisubunit enzyme composed of a peripheral complex (V1) that hydrolyzes ATP and a membrane integral complex (V0) that translocates protons (By similarity). V-ATPase is responsible for acidifying and maintaining the pH of intracellular compartments and in some cell types, is targeted to the plasma membrane, where it is responsible for acidifying the extracellular environment (By similarity). Seems to be directly involved in T-cell activation (PubMed:10329006)","subcellular_location":"Membrane","url":"https://www.uniprot.org/uniprotkb/Q13488/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TCIRG1","classification":"Not Classified","n_dependent_lines":10,"n_total_lines":1208,"dependency_fraction":0.008278145695364239},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/TCIRG1","total_profiled":1310},"omim":[{"mim_id":"615198","title":"OSTEOSCLEROTIC METAPHYSEAL DYSPLASIA; OSMD","url":"https://www.omim.org/entry/615198"},{"mim_id":"612301","title":"OSTEOPETROSIS, AUTOSOMAL RECESSIVE 7; OPTB7","url":"https://www.omim.org/entry/612301"},{"mim_id":"610986","title":"LEUCINE-RICH REPEAT KINASE 1; LRRK1","url":"https://www.omim.org/entry/610986"},{"mim_id":"607649","title":"OSTEOPETROSIS-ASSOCIATED TRANSMEMBRANE PROTEIN 1; OSTM1","url":"https://www.omim.org/entry/607649"},{"mim_id":"605239","title":"ATPase, H+ TRANSPORTING, LYSOSOMAL, V0 SUBUNIT A, ISOFORM 4; ATP6V0A4","url":"https://www.omim.org/entry/605239"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Mitochondria","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"pancreas","ntpm":278.3}],"url":"https://www.proteinatlas.org/search/TCIRG1"},"hgnc":{"alias_symbol":["TIRC7","OC-116","OC116","ATP6N1C","Atp6i","a3","ATP6V0A3"],"prev_symbol":[]},"alphafold":{"accession":"Q13488","domains":[{"cath_id":"-","chopping":"18-107_278-312_327-347","consensus_level":"medium","plddt":88.0329,"start":18,"end":347},{"cath_id":"3.30.70.2750","chopping":"120-135_166-272","consensus_level":"medium","plddt":86.4167,"start":120,"end":272},{"cath_id":"-","chopping":"386-475_510-655_711-810","consensus_level":"medium","plddt":89.3697,"start":386,"end":810}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13488","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q13488-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q13488-F1-predicted_aligned_error_v6.png","plddt_mean":83.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TCIRG1","jax_strain_url":"https://www.jax.org/strain/search?query=TCIRG1"},"sequence":{"accession":"Q13488","fasta_url":"https://rest.uniprot.org/uniprotkb/Q13488.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q13488/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13488"}},"corpus_meta":[{"pmid":"10888887","id":"PMC_10888887","title":"Defects in TCIRG1 subunit of the vacuolar proton pump are responsible for a subset of human autosomal recessive osteopetrosis.","date":"2000","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/10888887","citation_count":521,"is_preprint":false},{"pmid":"10581033","id":"PMC_10581033","title":"Atp6i-deficient mice exhibit severe osteopetrosis due to loss of osteoclast-mediated extracellular acidification.","date":"1999","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/10581033","citation_count":382,"is_preprint":false},{"pmid":"15300850","id":"PMC_15300850","title":"TCIRG1-dependent recessive osteopetrosis: mutation analysis, functional identification of the splicing defects, and in vitro rescue by U1 snRNA.","date":"2004","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/15300850","citation_count":84,"is_preprint":false},{"pmid":"12507890","id":"PMC_12507890","title":"Genotype-phenotype relationship in human ATP6i-dependent autosomal recessive osteopetrosis.","date":"2003","source":"The American journal of pathology","url":"https://pubmed.ncbi.nlm.nih.gov/12507890","citation_count":83,"is_preprint":false},{"pmid":"10329006","id":"PMC_10329006","title":"Genomic organization of the gene coding for TIRC7, a novel membrane protein essential for T cell activation.","date":"1999","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/10329006","citation_count":67,"is_preprint":false},{"pmid":"9806637","id":"PMC_9806637","title":"Prevention of acute allograft rejection by antibody targeting of TIRC7, a novel T cell membrane protein.","date":"1998","source":"Immunity","url":"https://pubmed.ncbi.nlm.nih.gov/9806637","citation_count":60,"is_preprint":false},{"pmid":"12552563","id":"PMC_12552563","title":"Novel mutations in the TCIRG1 gene encoding the a3 subunit of the vacuolar proton pump in patients affected by infantile malignant osteopetrosis.","date":"2003","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/12552563","citation_count":47,"is_preprint":false},{"pmid":"24108692","id":"PMC_24108692","title":"CLCN7 and TCIRG1 mutations differentially affect bone matrix mineralization in osteopetrotic individuals.","date":"2014","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/24108692","citation_count":38,"is_preprint":false},{"pmid":"24753205","id":"PMC_24753205","title":"TCIRG1-associated congenital neutropenia.","date":"2014","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/24753205","citation_count":36,"is_preprint":false},{"pmid":"22231430","id":"PMC_22231430","title":"Autosomal recessive osteopetrosis: report of 41 novel mutations in the TCIRG1 gene and diagnostic implications.","date":"2012","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/22231430","citation_count":35,"is_preprint":false},{"pmid":"25829125","id":"PMC_25829125","title":"Buried in the Middle but Guilty: Intronic Mutations in the TCIRG1 Gene Cause Human Autosomal Recessive Osteopetrosis.","date":"2015","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/25829125","citation_count":35,"is_preprint":false},{"pmid":"23577057","id":"PMC_23577057","title":"RNAi-mediated silencing of Atp6i and Atp6i haploinsufficiency prevents both bone loss and inflammation in a mouse model of periodontal disease.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23577057","citation_count":34,"is_preprint":false},{"pmid":"19172990","id":"PMC_19172990","title":"Genetic analysis of autosomal recessive osteopetrosis in Chuvashiya: the unique splice site mutation in TCIRG1 gene spread by the founder effect.","date":"2009","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/19172990","citation_count":32,"is_preprint":false},{"pmid":"11295466","id":"PMC_11295466","title":"Monitoring of intragraft and peripheral blood TIRC7 expression as a diagnostic tool for acute cardiac rejection in humans.","date":"2001","source":"Human immunology","url":"https://pubmed.ncbi.nlm.nih.gov/11295466","citation_count":29,"is_preprint":false},{"pmid":"23166162","id":"PMC_23166162","title":"RNA interference-mediated silencing of Atp6i prevents both periapical bone erosion and inflammation in the mouse model of endodontic disease.","date":"2013","source":"Infection and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/23166162","citation_count":29,"is_preprint":false},{"pmid":"15231021","id":"PMC_15231021","title":"In vitro differentiation of CD14 cells from osteopetrotic subjects: contrasting phenotypes with TCIRG1, CLCN7, and attachment defects.","date":"2004","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/15231021","citation_count":28,"is_preprint":false},{"pmid":"31949009","id":"PMC_31949009","title":"Expanded circulating hematopoietic stem/progenitor cells as novel cell source for the treatment of TCIRG1 osteopetrosis.","date":"2021","source":"Haematologica","url":"https://pubmed.ncbi.nlm.nih.gov/31949009","citation_count":25,"is_preprint":false},{"pmid":"15294947","id":"PMC_15294947","title":"TIRC7 deficiency causes in vitro and in vivo augmentation of T and B cell activation and cytokine response.","date":"2004","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/15294947","citation_count":24,"is_preprint":false},{"pmid":"14523594","id":"PMC_14523594","title":"Association between a polymorphism affecting an AP1 binding site in the promoter of the TCIRG1 gene and bone mass in women.","date":"2003","source":"Calcified tissue international","url":"https://pubmed.ncbi.nlm.nih.gov/14523594","citation_count":22,"is_preprint":false},{"pmid":"17082597","id":"PMC_17082597","title":"TIRC7 inhibits T cell proliferation by modulation of CTLA-4 expression.","date":"2006","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/17082597","citation_count":21,"is_preprint":false},{"pmid":"30537558","id":"PMC_30537558","title":"Sclerosing bone dysplasias with hallmarks of dysosteosclerosis in four patients carrying mutations in SLC29A3 and TCIRG1.","date":"2018","source":"Bone","url":"https://pubmed.ncbi.nlm.nih.gov/30537558","citation_count":21,"is_preprint":false},{"pmid":"24535816","id":"PMC_24535816","title":"As little as needed: the extraordinary case of a mild recessive osteopetrosis owing to a novel splicing hypomorphic mutation in the TCIRG1 gene.","date":"2014","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/24535816","citation_count":21,"is_preprint":false},{"pmid":"20711468","id":"PMC_20711468","title":"Optic nerve compression and retinal degeneration in Tcirg1 mutant mice lacking the vacuolar-type H-ATPase a3 subunit.","date":"2010","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/20711468","citation_count":21,"is_preprint":false},{"pmid":"15023142","id":"PMC_15023142","title":"Monoclonal antibody specific for TIRC7 induces donor-specific anergy and prevents rejection of cardiac allografts in mice.","date":"2004","source":"American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons","url":"https://pubmed.ncbi.nlm.nih.gov/15023142","citation_count":19,"is_preprint":false},{"pmid":"18648057","id":"PMC_18648057","title":"Ovocleidin (OC 116) is present in avian skeletal tissues.","date":"2008","source":"Poultry science","url":"https://pubmed.ncbi.nlm.nih.gov/18648057","citation_count":18,"is_preprint":false},{"pmid":"37649034","id":"PMC_37649034","title":"Glycolysis-related biomarker TCIRG1 participates in regulation of renal cell carcinoma progression and tumor immune microenvironment by affecting aerobic glycolysis and AKT/mTOR signaling pathway.","date":"2023","source":"Cancer cell international","url":"https://pubmed.ncbi.nlm.nih.gov/37649034","citation_count":18,"is_preprint":false},{"pmid":"35981697","id":"PMC_35981697","title":"Osteoclast rich osteopetrosis due to defects in the TCIRG1 gene.","date":"2022","source":"Bone","url":"https://pubmed.ncbi.nlm.nih.gov/35981697","citation_count":17,"is_preprint":false},{"pmid":"18424726","id":"PMC_18424726","title":"Characterization of IL-10-secreting T cells derived from regulatory CD4+CD25+ cells by the TIRC7 surface marker.","date":"2008","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/18424726","citation_count":17,"is_preprint":false},{"pmid":"16542376","id":"PMC_16542376","title":"Antibody targeting of TIRC7 results in significant therapeutic effects on collagen-induced arthritis in mice.","date":"2006","source":"Clinical and experimental immunology","url":"https://pubmed.ncbi.nlm.nih.gov/16542376","citation_count":17,"is_preprint":false},{"pmid":"12161516","id":"PMC_12161516","title":"Sibling pair linkage and association studies between peak bone mineral density and the gene locus for the osteoclast-specific subunit (OC116) of the vacuolar proton pump on chromosome 11p12-13.","date":"2002","source":"The Journal of clinical endocrinology and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/12161516","citation_count":17,"is_preprint":false},{"pmid":"35573728","id":"PMC_35573728","title":"Novel Disease-Associated Missense Single-Nucleotide Polymorphisms Variants Predication by Algorithms Tools and Molecular Dynamics Simulation of Human TCIRG1 Gene Causing Congenital Neutropenia and Osteopetrosis.","date":"2022","source":"Frontiers in molecular biosciences","url":"https://pubmed.ncbi.nlm.nih.gov/35573728","citation_count":17,"is_preprint":false},{"pmid":"23907031","id":"PMC_23907031","title":"Lentiviral gene transfer of TCIRG1 into peripheral blood CD34(+) cells restores osteoclast function in infantile malignant osteopetrosis.","date":"2013","source":"Bone","url":"https://pubmed.ncbi.nlm.nih.gov/23907031","citation_count":16,"is_preprint":false},{"pmid":"22245629","id":"PMC_22245629","title":"Murine ameloblasts are immunonegative for Tcirg1, the v-H-ATPase subunit essential for the osteoclast plasma proton pump.","date":"2012","source":"Bone","url":"https://pubmed.ncbi.nlm.nih.gov/22245629","citation_count":16,"is_preprint":false},{"pmid":"28816234","id":"PMC_28816234","title":"Novel mutations of TCIRG1 cause a malignant and mild phenotype of autosomal recessive osteopetrosis (ARO) in four Chinese families.","date":"2017","source":"Acta pharmacologica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/28816234","citation_count":16,"is_preprint":false},{"pmid":"20665709","id":"PMC_20665709","title":"OC-116, the chicken ortholog of mammalian MEPE found in eggshell, is also expressed in bone cells.","date":"2010","source":"Journal of experimental zoology. Part B, Molecular and developmental evolution","url":"https://pubmed.ncbi.nlm.nih.gov/20665709","citation_count":16,"is_preprint":false},{"pmid":"31111556","id":"PMC_31111556","title":"Novel c.G630A TCIRG1 mutation causes aberrant splicing resulting in an unusually mild form of autosomal recessive osteopetrosis.","date":"2019","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/31111556","citation_count":13,"is_preprint":false},{"pmid":"15809087","id":"PMC_15809087","title":"Identification of new alternative splice events in the TCIRG1 gene in different human tissues.","date":"2005","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/15809087","citation_count":13,"is_preprint":false},{"pmid":"27229898","id":"PMC_27229898","title":"Association Between Absolute Neutrophil Count and Variation at TCIRG1: The NHLBI Exome Sequencing Project.","date":"2016","source":"Genetic epidemiology","url":"https://pubmed.ncbi.nlm.nih.gov/27229898","citation_count":13,"is_preprint":false},{"pmid":"27541021","id":"PMC_27541021","title":"Regulation and Function of Lentiviral Vector-Mediated TCIRG1 Expression in Osteoclasts from Patients with Infantile Malignant Osteopetrosis: Implications for Gene Therapy.","date":"2016","source":"Calcified tissue international","url":"https://pubmed.ncbi.nlm.nih.gov/27541021","citation_count":13,"is_preprint":false},{"pmid":"17138060","id":"PMC_17138060","title":"TIRC7 is induced in rejected human kidneys and anti-TIRC7 mAb with FK506 prolongs survival of kidney allografts in rats.","date":"2006","source":"Transplant immunology","url":"https://pubmed.ncbi.nlm.nih.gov/17138060","citation_count":12,"is_preprint":false},{"pmid":"18270567","id":"PMC_18270567","title":"HLA-DR alpha 2 mediates negative signalling via binding to Tirc7 leading to anti-inflammatory and apoptotic effects in lymphocytes in vitro and in vivo.","date":"2008","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/18270567","citation_count":12,"is_preprint":false},{"pmid":"32790690","id":"PMC_32790690","title":"Knockdown of Tcirg1 inhibits large-osteoclast generation by down-regulating NFATc1 and IP3R2 expression.","date":"2020","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/32790690","citation_count":12,"is_preprint":false},{"pmid":"31938717","id":"PMC_31938717","title":"Generation of an immunodeficient mouse model of tcirg1-deficient autosomal recessive osteopetrosis.","date":"2020","source":"Bone reports","url":"https://pubmed.ncbi.nlm.nih.gov/31938717","citation_count":11,"is_preprint":false},{"pmid":"23412864","id":"PMC_23412864","title":"A case of autosomal dominant osteopetrosis type II with a novel TCIRG1 gene mutation.","date":"2013","source":"Journal of pediatric endocrinology & metabolism : JPEM","url":"https://pubmed.ncbi.nlm.nih.gov/23412864","citation_count":11,"is_preprint":false},{"pmid":"24898387","id":"PMC_24898387","title":"Epiregulin (EREG) and human V-ATPase (TCIRG1): genetic variation, ethnicity and pulmonary tuberculosis susceptibility in Guinea-Bissau and The Gambia.","date":"2014","source":"Genes and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/24898387","citation_count":10,"is_preprint":false},{"pmid":"21472218","id":"PMC_21472218","title":"Fluid shear stress changes cell morphology and regulates the expression of ATP6V1A and TCIRG1 mRNA in rat osteoclasts.","date":"2010","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/21472218","citation_count":10,"is_preprint":false},{"pmid":"30898715","id":"PMC_30898715","title":"TCIRG1 and SNX10 gene mutations in the patients with autosomal recessive osteopetrosis.","date":"2019","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/30898715","citation_count":9,"is_preprint":false},{"pmid":"24535484","id":"PMC_24535484","title":"Identification of TCIRG1 and CLCN7 gene mutations in a patient with autosomal recessive osteopetrosis.","date":"2014","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/24535484","citation_count":9,"is_preprint":false},{"pmid":"21042819","id":"PMC_21042819","title":"Novel mutation of TCIRG1 and clinical pictures of two infantile malignant osteopetrosis patients.","date":"2010","source":"Journal of bone and mineral metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/21042819","citation_count":9,"is_preprint":false},{"pmid":"30084437","id":"PMC_30084437","title":"Autosomal recessive osteopetrosis type I: description of pathogenic variant of TCIRG1 gene.","date":"2018","source":"Boletin medico del Hospital Infantil de Mexico","url":"https://pubmed.ncbi.nlm.nih.gov/30084437","citation_count":9,"is_preprint":false},{"pmid":"18715141","id":"PMC_18715141","title":"Characterization of a novel Alu-Alu recombination-mediated genomic deletion in the TCIRG1 gene in five osteopetrotic patients.","date":"2009","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/18715141","citation_count":9,"is_preprint":false},{"pmid":"31567691","id":"PMC_31567691","title":"TCIRG1 Transgenic Rescue of Osteoclast Function Using Induced Pluripotent Stem Cells Derived from Patients with Infantile Malignant Autosomal Recessive Osteopetrosis.","date":"2019","source":"The Journal of bone and joint surgery. American volume","url":"https://pubmed.ncbi.nlm.nih.gov/31567691","citation_count":9,"is_preprint":false},{"pmid":"37599332","id":"PMC_37599332","title":"Atp6i deficient mouse model uncovers transforming growth factor-β1 /Smad2/3 as a key signaling pathway regulating odontoblast differentiation and tooth root formation.","date":"2023","source":"International journal of oral science","url":"https://pubmed.ncbi.nlm.nih.gov/37599332","citation_count":7,"is_preprint":false},{"pmid":"12687885","id":"PMC_12687885","title":"Osteoclast morphology in autosomal recessive malignant osteopetrosis due to a TCIRG1 gene mutation.","date":"2003","source":"Pediatric pathology & molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/12687885","citation_count":7,"is_preprint":false},{"pmid":"28844534","id":"PMC_28844534","title":"Eggshell matrix proteins OC-116, OC-17 and OCX36 in hen's sperm storage tubules.","date":"2017","source":"Animal reproduction science","url":"https://pubmed.ncbi.nlm.nih.gov/28844534","citation_count":7,"is_preprint":false},{"pmid":"24989235","id":"PMC_24989235","title":"A founder mutation in the TCIRG1 gene causes osteopetrosis in the Ashkenazi Jewish population.","date":"2014","source":"Clinical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/24989235","citation_count":6,"is_preprint":false},{"pmid":"30539151","id":"PMC_30539151","title":"Ophthalmic phenotype of TCIRG1 gene mutations in Chinese infantile malignant osteopetrosis.","date":"2018","source":"BMJ open ophthalmology","url":"https://pubmed.ncbi.nlm.nih.gov/30539151","citation_count":6,"is_preprint":false},{"pmid":"15883619","id":"PMC_15883619","title":"TIRC7 pathway as a target for preventing allograft rejection.","date":"2005","source":"Drug news & perspectives","url":"https://pubmed.ncbi.nlm.nih.gov/15883619","citation_count":6,"is_preprint":false},{"pmid":"31794943","id":"PMC_31794943","title":"Generation of 3 clones of induced pluripotent stem cells (iPSCs) from a patient affected by Autosomal Recessive Osteopetrosis due to mutations in TCIRG1 gene.","date":"2019","source":"Stem cell research","url":"https://pubmed.ncbi.nlm.nih.gov/31794943","citation_count":6,"is_preprint":false},{"pmid":"32319655","id":"PMC_32319655","title":"TIRC7 inhibits Th1 cells by upregulating the expression of CTLA‑4 and STAT3 in mice with acute graft‑versus‑host disease.","date":"2020","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/32319655","citation_count":5,"is_preprint":false},{"pmid":"30431110","id":"PMC_30431110","title":"CLCN7 and TCIRG1 mutations in a single family: Evidence for digenic inheritance of osteopetrosis.","date":"2018","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/30431110","citation_count":5,"is_preprint":false},{"pmid":"38261998","id":"PMC_38261998","title":"Autosomal Dominant Osteopetrosis (ADO) Caused by a Missense Variant in the TCIRG1 Gene.","date":"2024","source":"The Journal of clinical endocrinology and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/38261998","citation_count":5,"is_preprint":false},{"pmid":"22280207","id":"PMC_22280207","title":"A novel TCIRG1 gene mutation leads to severe osteopetrosis with altered content of monocytes/macrophages in several organs.","date":"2012","source":"Pediatric and developmental pathology : the official journal of the Society for Pediatric Pathology and the Paediatric Pathology Society","url":"https://pubmed.ncbi.nlm.nih.gov/22280207","citation_count":4,"is_preprint":false},{"pmid":"24526664","id":"PMC_24526664","title":"TIRC7 and HLA-DR axis contributes to inflammation in multiple sclerosis.","date":"2014","source":"Multiple sclerosis (Houndmills, Basingstoke, England)","url":"https://pubmed.ncbi.nlm.nih.gov/24526664","citation_count":4,"is_preprint":false},{"pmid":"28604959","id":"PMC_28604959","title":"[Analysis of TCIRG1 gene mutation in a Chinese family affected with infantile malignant osteopetrosis].","date":"2017","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/28604959","citation_count":3,"is_preprint":false},{"pmid":"22015593","id":"PMC_22015593","title":"Monocytes differentiation upon treatment with a peptide corresponding to the C-terminus of activated T cell-expressed Tirc7 protein.","date":"2012","source":"Journal of cellular physiology","url":"https://pubmed.ncbi.nlm.nih.gov/22015593","citation_count":2,"is_preprint":false},{"pmid":"29723947","id":"PMC_29723947","title":"[Identification of new mutations in TCIRG1 as a cause of infantile malignant osteopetrosis in two Mexican patients].","date":"2018","source":"Revista alergia Mexico (Tecamachalco, Puebla, Mexico : 1993)","url":"https://pubmed.ncbi.nlm.nih.gov/29723947","citation_count":2,"is_preprint":false},{"pmid":"40995561","id":"PMC_40995561","title":"Tcirg1 deficiency delays osteoarthritis progression by impairing lysosome acidification and peripheral accumulation in osteoclasts.","date":"2025","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/40995561","citation_count":1,"is_preprint":false},{"pmid":"34210262","id":"PMC_34210262","title":"Two novel mutations in TCIRG1 induced infantile malignant osteopetrosis: a case report.","date":"2021","source":"BMC pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/34210262","citation_count":1,"is_preprint":false},{"pmid":"37107657","id":"PMC_37107657","title":"Outlining the Clinical Profile of TCIRG1 14 Variants including 5 Novels with Overview of ARO Phenotype and Ethnic Impact in 20 Egyptian Families.","date":"2023","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/37107657","citation_count":1,"is_preprint":false},{"pmid":"39267677","id":"PMC_39267677","title":"VMA21: unveiling a novel oncogene that facilitates immune evasion in triple-negative breast cancer through TCIRG1 protein stability regulation.","date":"2024","source":"American journal of cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/39267677","citation_count":0,"is_preprint":false},{"pmid":"41673363","id":"PMC_41673363","title":"Single-Cell Multiomics Decoding of TCIRG1-Mediated Cuproptosis Circuitry Rewiring Immune-Metabolic Landscape in Ischemic Stroke.","date":"2026","source":"Translational stroke research","url":"https://pubmed.ncbi.nlm.nih.gov/41673363","citation_count":0,"is_preprint":false},{"pmid":"40964614","id":"PMC_40964614","title":"Modeling TCIRG1 Neutropenia by Utilizing Patient Derived Induced Pluripotent Stem Cells.","date":"2025","source":"Journal of cellular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/40964614","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":37539,"output_tokens":6158,"usd":0.102494},"stage2":{"model":"claude-opus-4-6","input_tokens":9786,"output_tokens":3840,"usd":0.217395},"total_usd":0.319889,"stage1_batch_id":"msgbatch_01RPbVc9PDH9zQmYK5Hs6srm","stage2_batch_id":"msgbatch_01JVbVLzeKN2yVrsGp3zC8aM","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2000,\n      \"finding\": \"TCIRG1 encodes the osteoclast-specific 116-kDa subunit (a3) of the vacuolar proton pump (V-ATPase), and loss-of-function mutations in TCIRG1 cause autosomal recessive osteopetrosis by impairing osteoclast function (not differentiation), establishing TCIRG1 as essential for mature osteoclast resorptive activity.\",\n      \"method\": \"Mutation analysis in osteopetrosis patients; functional correlation with osteoclast presence/absence\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — foundational disease-gene identification, replicated across multiple patient cohorts and confirmed by mouse knockout\",\n      \"pmids\": [\"10888887\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Targeted disruption of Atp6i (mouse ortholog of TCIRG1) results in severe osteopetrosis; Atp6i-/- osteoclasts lose extracellular acidification function but retain intracellular lysosomal proton pump activity, demonstrating that the a3 subunit is specifically required for plasma membrane-directed extracellular acidification by osteoclasts.\",\n      \"method\": \"Gene knockout mouse model; pH measurement in lysosomes; proton transport assay in kidney microsomes; acid-base balance measurement\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — knockout model with multiple orthogonal functional assays, foundational mechanistic study\",\n      \"pmids\": [\"10581033\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"In vitro-differentiated osteoclasts from patients with TCIRG1 compound heterozygous mutations can fuse and attach to bone but fail to acidify the resorption compartment, consistent with TCIRG1 being essential for H+-ATPase assembly at the ruffled border; by contrast, CLCN7 defects impair organic matrix removal rather than acidification.\",\n      \"method\": \"CD14+ monocyte differentiation into osteoclasts; acid secretion assay; bone pit assay; genotype correlation\",\n      \"journal\": \"Journal of bone and mineral research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct functional assays in patient-derived cells with genotype-phenotype correlation\",\n      \"pmids\": [\"15231021\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"TCIRG1 (ATP6i/a3) mutations cause osteopetrosis with osteoclasts that are morphologically normal (normal actin rings, clear zones, podosomes, αVβ3, c-Src, PYK2) but excavate only faint, shallow pits, confirming the specific role of the a3 subunit in bone acidification rather than osteoclast cytoskeletal organization.\",\n      \"method\": \"Bone biopsy histology; in vitro osteoclast differentiation from patient CD14+ cells; TRAP activity; bone resorption pit assay; immunostaining\",\n      \"journal\": \"The American journal of pathology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods in patient-derived cells, confirms functional specificity\",\n      \"pmids\": [\"12507890\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Post-transplant osteoclasts in TCIRG1-deficient patients rescue a3 subunit immunoreactivity, demonstrating that donor-derived osteoclasts restore V-ATPase a3 expression and function, confirming the cell-autonomous nature of the TCIRG1 defect.\",\n      \"method\": \"Bone marrow transplantation with post-transplant immunostaining for a3 subunit\",\n      \"journal\": \"The American journal of pathology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct rescue experiment, single study\",\n      \"pmids\": [\"12507890\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"TCIRG1/TIRC7 are alternative transcripts of the same gene located on chromosome 11q13.4-q13.5; TIRC7 (TV2, 7-transmembrane domain isoform) is expressed in alloactivated T lymphocytes while OC116 (TV1) is the osteoclast-specific V-ATPase subunit, establishing tissue-specific alternative splicing of the locus.\",\n      \"method\": \"Genomic organization analysis; RT-PCR in human T lymphocytes; exon-intron mapping\",\n      \"journal\": \"Genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct molecular characterization of transcript variants\",\n      \"pmids\": [\"10329006\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"TIRC7 (the T-cell isoform of TCIRG1) functions as a membrane protein essential for T cell activation; anti-TIRC7 antibodies inhibit human T cell proliferation and IL-2 secretion in vitro, and specifically suppress IFN-γ (Th1) but not IL-4 (Th2) expression; cross-reactive antibody prolonged rat kidney allograft survival in vivo.\",\n      \"method\": \"In vitro T cell proliferation assay; cytokine ELISA; rat kidney allograft model with anti-TIRC7 antibody treatment\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional inhibition experiments in vitro and in vivo, single lab\",\n      \"pmids\": [\"9806637\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"TIRC7-deficient mice exhibit increased T and B cell proliferation and cytokine production (IL-2, IFN-γ, IL-4), reduced CTLA-4 expression on activated T cells, expanded memory/effector T cells (CD62L↓, CD11a↑, CD44↑), B cell hyperreactivity, and augmented delayed-type hypersensitivity, establishing TIRC7 as a negative regulator of lymphocyte activation.\",\n      \"method\": \"Gene-targeted TIRC7 knockout mice; in vitro T and B cell proliferation assays; cytokine measurement; flow cytometry; delayed-type hypersensitivity assay\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic knockout with multiple orthogonal readouts, strong evidence for regulatory role\",\n      \"pmids\": [\"15294947\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Anti-TIRC7 antibody induces early surface expression of CTLA-4; TIRC7 and CTLA-4 colocalize in T cells and both associate with clathrin-coated vesicles sharing intracellular transport systems; TIRC7-mediated inhibition of T cell proliferation is abolished by CTLA-4 blockade or in CTLA-4-deficient mouse splenocytes, placing TIRC7 upstream of CTLA-4 in the T cell inhibitory pathway.\",\n      \"method\": \"Immunofluorescence colocalization; flow cytometry; CTLA-4 antibody blockade; CTLA-4 knockout splenocyte experiments; transcription activation assay\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — epistasis established by multiple methods including knockout rescue, mechanistic pathway defined\",\n      \"pmids\": [\"17082597\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"HLA-DR alpha 2 domain directly binds TIRC7 on lymphocytes, delivering negative signals that inhibit proliferation and induce apoptosis in CD4+ and CD8+ T cells via the intrinsic apoptotic pathway; this interaction recruits SHP-1 to TIRC7, decreases phosphorylation of STAT4, TCR-zeta chain and ZAP70, and inhibits IFN-γ and FasL expression; HLA-DRα2 and TIRC7 co-localize at the APC–T cell interaction site.\",\n      \"method\": \"Pulldown/co-localization; SHP-1 recruitment assay; phosphorylation assays; apoptosis assay; in vivo LPS model\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — binding partner identified, downstream signaling cascade characterized with multiple orthogonal methods\",\n      \"pmids\": [\"18270567\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"In Tcirg1-/- mice, the a3 subunit accumulates in choriocapillary meshwork of uveal tissues; loss of a3 leads to narrowed skull foramina causing optic nerve compression and increased retinal apoptosis; compensatory upregulation of the a4 V-ATPase subunit isoform occurs in mutant choriocapillary meshwork, revealing isoform compensation among V-ATPase a-subunits.\",\n      \"method\": \"X-ray microtomography; immunohistochemistry for V-ATPase subunit isoforms; apoptosis assay in retina; Tcirg1-/- mouse model\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization and functional consequence demonstrated in knockout model\",\n      \"pmids\": [\"20711468\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Tcirg1 (a3 subunit) is not detectably expressed in mouse maturation-stage ameloblasts despite their use of V-ATPase; Tcirg1-null mice have normal enamel formation and mineral content, demonstrating that the osteoclast-type plasma membrane proton pump using the a3 subunit is not required for ameloblast enamel acidification.\",\n      \"method\": \"Immunohistochemistry; mineral content analysis; Tcirg1 null mouse model analysis\",\n      \"journal\": \"Bone\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization with functional consequence in knockout model\",\n      \"pmids\": [\"22245629\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Lentiviral gene transfer of TCIRG1 cDNA into peripheral blood CD34+ cells from infantile malignant osteopetrosis patients restores osteoclast bone resorption to ~70-80% of normal, as measured by Ca2+ release, CTX-I bone degradation product, and resorption pit formation, demonstrating that re-expression of TCIRG1 is sufficient to restore V-ATPase-dependent osteoclast function.\",\n      \"method\": \"Lentiviral transduction; qPCR; Western blot; Ca2+ release assay; CTX-I ELISA; bone resorption pit assay; NSG mouse engraftment\",\n      \"journal\": \"Bone\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — functional rescue by gene complementation with multiple orthogonal readouts\",\n      \"pmids\": [\"23907031\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"AAV-mediated RNAi knockdown of Atp6i/TCIRG1 in periodontal tissues impairs osteoclast extracellular acidification and bone resorption, and also reduces T-cell infiltration and inflammatory cytokine expression; Atp6i+/- haploinsufficient mice are similarly protected from P. gingivalis-induced bone loss and gingival inflammation, establishing a dual role for Atp6i in bone resorption and tissue inflammation.\",\n      \"method\": \"AAV-shRNA delivery in vivo; bone resorption quantification; T-cell number measurement; cytokine gene expression; Atp6i+/- haploinsufficiency model\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo loss-of-function with multiple readouts, confirmed by haploinsufficiency model\",\n      \"pmids\": [\"23577057\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"TCIRG1 mutations (but not CLCN7 or TNFRSF11A mutations) are specifically associated with severe osteoid accumulation and decreased calcium content in bone matrix (osteomalacia), demonstrating that loss of V-ATPase a3 specifically impairs bone matrix mineralization in addition to bone resorption.\",\n      \"method\": \"Undecalcified iliac crest biopsy histology; calcium content analysis; genotype-phenotype comparison across osteopetrosis subtypes\",\n      \"journal\": \"Journal of bone and mineral research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct genotype-phenotype correlation with histological evidence across multiple patients and subtypes\",\n      \"pmids\": [\"24108692\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"TCIRG1 protein expression from a bicistronic lentiviral vector is post-transcriptionally regulated: protein accumulates only in mature osteoclasts, not in precursors or macrophages, preventing ectopic overexpression; codon optimization increased mRNA but paradoxically lowered protein and functional rescue, revealing post-transcriptional control of TCIRG1 expression.\",\n      \"method\": \"Lentiviral vector expression analysis; flow cytometry; Western blot at different differentiation stages; codon optimization comparison; bone resorption assay\",\n      \"journal\": \"Calcified tissue international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct mechanistic finding on post-transcriptional regulation, single lab\",\n      \"pmids\": [\"27541021\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Transgenic TCIRG1 expression in iPSC-derived osteoclasts from an infantile malignant osteopetrosis patient restores cathepsin K (CTSK) and TRAP expression and rescues pit formation, establishing that TCIRG1 function is required for downstream expression of bone remodeling enzymes in addition to proton pumping.\",\n      \"method\": \"iPSC generation from patient fibroblasts; osteoclast differentiation; transgenic TCIRG1 rescue; qPCR for CTSK/TRAP; pit formation assay\",\n      \"journal\": \"The Journal of bone and joint surgery. American volume\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic rescue experiment with multiple functional readouts, single lab\",\n      \"pmids\": [\"31567691\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Knockdown of Tcirg1 in mouse bone marrow-derived monocytes inhibits formation of large osteoclasts (>100 μm) by decreasing NFATc1 and IP3R2 expression; reduced IP3R2 lowers intracellular calcium levels, which limits nuclear translocation of NFATc1 during RANKL-induced osteoclastogenesis.\",\n      \"method\": \"Lentiviral shRNA knockdown; osteoclast size quantification; NFATc1 and IP3R2 expression assay; intracellular calcium measurement; nuclear translocation assay\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — mechanistic pathway defined with multiple readouts, single lab\",\n      \"pmids\": [\"32790690\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"A peptide corresponding to the C-terminus of Tirc7 (the T-cell isoform of Atp6v0a3/TCIRG1) induces differentiation of RAW264.7 cells and bone marrow CD11b+ cells into TRAP-positive multinucleated osteoclast-like cells and stimulates an autocrine/paracrine regulatory loop, revealing that the extracellular C-terminus of Tirc7 directly signals to osteoclast precursor cells.\",\n      \"method\": \"Molecular cloning of Tirc7 C-terminal peptide; treatment of RAW264.7, CD11b+ cells, and primary monocytes; TRAP staining; multinucleation assay; F4/80 immunostaining\",\n      \"journal\": \"Journal of cellular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single lab, peptide gain-of-function approach with multiple cell type readouts\",\n      \"pmids\": [\"22015593\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In Atp6i-/- mice, osteoclast dysfunction prevents TGF-β1 release from alveolar bone matrix, impairing TGF-β1/Smad2/3 signaling in radicular odontoblasts and arresting tooth root formation; ectopic TGF-β1 partially rescues root development in Atp6i-/- tooth germ transplants, placing Atp6i-dependent bone resorption upstream of TGF-β1 release required for odontoblast differentiation.\",\n      \"method\": \"Atp6i-/- mouse model; RNA-seq; qPCR for odontoblast markers; Smad2/3 phosphorylation assay; anti-TGF-β1 neutralization; conditioned medium experiments; kidney capsule transplantation rescue\",\n      \"journal\": \"International journal of oral science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — epistasis established with multiple orthogonal methods and rescue experiment, single lab\",\n      \"pmids\": [\"37599332\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"TCIRG1 deficiency in knockout mice delays osteoarthritis progression; in vitro, Tcirg1 knockdown in osteoclasts inhibits cell fusion and bone resorption by impairing lysosome acidification and peripheral lysosome accumulation, establishing a role for the a3 subunit in lysosomal trafficking to the cell periphery during osteoclast activation.\",\n      \"method\": \"Tcirg1-knockout OA mouse model (DMM surgery); histology; micro-CT; in vitro osteoclast differentiation with shRNA knockdown; lysosome acidification and distribution assays\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo knockout model plus in vitro mechanistic assays, single study\",\n      \"pmids\": [\"40995561\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"iPSCs from congenital neutropenia patients bearing heterozygous TCIRG1 mutations (R736C, R736S, R736P, E722D) show defects in myeloid differentiation and increased cell death; CRISPR/Cas9 correction of R736C restores normal neutrophil differentiation; mutant TCIRG1 protein shows reduced expression and a more diffuse cytosolic distribution instead of normal vesicular/V-ATPase localization.\",\n      \"method\": \"iPSC generation; in vitro hematopoietic differentiation; CRISPR/Cas9 correction; immunofluorescence for TCIRG1 localization; neutrophil differentiation assay\",\n      \"journal\": \"Journal of cellular immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — CRISPR genetic rescue confirms pathogenicity, localization defect identified, single study\",\n      \"pmids\": [\"40964614\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"VMA21 stabilizes TCIRG1 protein by binding to it and inhibiting its ubiquitination-dependent degradation in triple-negative breast cancer cells, establishing VMA21 as a regulator of TCIRG1 protein stability through the ubiquitin-proteasome pathway.\",\n      \"method\": \"Immunoprecipitation; ubiquitination assay; VMA21 knockdown with TCIRG1 protein level measurement\",\n      \"journal\": \"American journal of cancer research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single Co-IP/ubiquitination assay in cancer cell line context, not validated in osteoclast biology\",\n      \"pmids\": [\"39267677\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Splicing mutations in TCIRG1 flanking splice sites (c.117+4A>T, c.1673+5G>A, c.504-8G>A) cause aberrant mRNA processing demonstrated in hybrid minigene assays; complementary U1 snRNA corrects the c.117+4A>T 5' splice site defect but not the c.1673+5G>A mutation, revealing mechanistic differences between mutations near invariant GT donor sites and those further from splice junctions.\",\n      \"method\": \"Hybrid minigene splicing assay; U1 snRNA cotransfection rescue experiments\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution of splicing defect and mechanistic rescue, single lab\",\n      \"pmids\": [\"15300850\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The TCIRG1 c.G630A mutation causes exons 5-6 skipping (ΔE56); the ΔE56 truncated protein lacking part of the cytoplasmic N-terminal domain fails to support V-ATPase-mediated vacuolar acidification in yeast (Vph1p ortholog growth assay on Zn2+-containing plates), demonstrating that exons 5-6 encode a functionally essential domain for V-ATPase activity.\",\n      \"method\": \"RT-PCR splicing analysis; yeast complementation assay (Vph1p); osteoclast differentiation and bone resorption assay; TCIRG1 Western blot\",\n      \"journal\": \"Journal of cellular biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 — yeast functional assay plus patient osteoclast phenotype, single lab\",\n      \"pmids\": [\"31111556\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TCIRG1 encodes the a3 subunit (OC-116) of the vacuolar H+-ATPase (V-ATPase), which is essential for osteoclast-mediated extracellular acidification at the ruffled border: the protein is required for plasma membrane-directed proton pumping to dissolve bone mineral, for lysosome acidification and peripheral trafficking during bone resorption, and for downstream expression of bone remodeling enzymes (cathepsin K, TRAP); an alternative transcript (TIRC7) functions as a T-cell co-inhibitory receptor that acts upstream of CTLA-4 through HLA-DRα2 binding, SHP-1 recruitment, and inhibition of TCR-proximal signaling, while its protein stability is regulated by VMA21-mediated protection from ubiquitin-dependent degradation.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"TCIRG1 encodes the a3 subunit of the vacuolar H⁺-ATPase (V-ATPase), a proton pump component that is essential for osteoclast-mediated extracellular acidification at the ruffled border and for lysosomal acidification and peripheral trafficking during bone resorption [PMID:10581033, PMID:15231021, PMID:40995561]. Loss-of-function mutations cause autosomal recessive infantile malignant osteopetrosis: TCIRG1-deficient osteoclasts differentiate and polarize normally but fail to acidify the resorption lacuna, and re-expression by lentiviral gene transfer rescues bone resorption to near-normal levels [PMID:10888887, PMID:12507890, PMID:23907031]. An alternative transcript (TIRC7) produces a T-cell co-inhibitory receptor that binds HLA-DRα2, recruits SHP-1, suppresses TCR-proximal signaling (ZAP70, TCR-ζ, STAT4 phosphorylation), and acts upstream of CTLA-4 surface expression to limit lymphocyte activation [PMID:9806637, PMID:15294947, PMID:17082597, PMID:18270567]. TCIRG1 also influences osteoclast fusion through an IP3R2–NFATc1 calcium-signaling axis, promotes downstream expression of bone-remodeling enzymes cathepsin K and TRAP, and its protein stability is regulated by VMA21-mediated protection from ubiquitin-dependent degradation [PMID:32790690, PMID:31567691, PMID:39267677].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Whether the TIRC7 gene product had any functional role in T cells was unknown; antibody-blocking experiments revealed that TIRC7 is a membrane protein required for T cell proliferation, IL-2 secretion, and Th1-skewed cytokine production, and that anti-TIRC7 antibody prolongs allograft survival, establishing the first evidence of an immune-regulatory function at this locus.\",\n      \"evidence\": \"In vitro T cell proliferation/cytokine assays and rat kidney allograft model with anti-TIRC7 antibody\",\n      \"pmids\": [\"9806637\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; mechanism of TIRC7 signaling undefined\", \"Relationship between TIRC7 and the osteoclast isoform not yet clarified\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"The molecular identity of the osteoclast-specific V-ATPase a-subunit and its relationship to TIRC7 were unresolved; genomic analysis demonstrated that TCIRG1 and TIRC7 are alternative transcripts of the same gene at 11q13, with the osteoclast isoform (OC116/TV1) and the T-cell isoform (TV2) arising from tissue-specific alternative splicing, and knockout of the mouse ortholog Atp6i caused severe osteopetrosis with loss of extracellular but not lysosomal acidification.\",\n      \"evidence\": \"Genomic exon-intron mapping; RT-PCR; Atp6i knockout mice with pH and proton transport assays\",\n      \"pmids\": [\"10329006\", \"10581033\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether a3 loss affects V-ATPase assembly versus membrane targeting unclear\", \"Mechanism of isoform-specific plasma membrane versus lysosome localization not defined\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Whether human osteopetrosis was caused by TCIRG1 mutations was unknown; mutation analysis across patient cohorts identified loss-of-function TCIRG1 mutations as the most common cause of autosomal recessive osteopetrosis, confirming that osteoclasts are present but functionally impaired.\",\n      \"evidence\": \"Mutation screening in osteopetrosis patient cohorts with genotype-phenotype correlation\",\n      \"pmids\": [\"10888887\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of individual mutations not characterized\", \"Whether haploinsufficiency causes disease unclear\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Whether TCIRG1-deficient osteoclasts had broader cytoskeletal or differentiation defects was unknown; detailed phenotyping showed that mutant osteoclasts form normal actin rings, clear zones, and podosomes but specifically fail to acidify the resorption compartment, while bone marrow transplant rescued a3 expression, confirming a cell-autonomous acidification defect.\",\n      \"evidence\": \"Patient-derived osteoclast differentiation, resorption pit assays, immunostaining for cytoskeletal markers, post-transplant biopsy immunohistochemistry\",\n      \"pmids\": [\"12507890\", \"15231021\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether mutant V-ATPase complexes assemble but mislocalize versus fail to assemble not resolved\", \"Effect on osteoclast secretory pathway not examined\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Whether TIRC7 was necessary for immune homeostasis in vivo was unresolved; TIRC7-knockout mice showed hyperproliferation of T and B cells, augmented cytokine production, reduced CTLA-4 expression, and enhanced delayed-type hypersensitivity, establishing TIRC7 as a non-redundant negative regulator of lymphocyte activation.\",\n      \"evidence\": \"Gene-targeted TIRC7 knockout mice; proliferation assays; flow cytometry; DTH assay\",\n      \"pmids\": [\"15294947\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Signaling pathway downstream of TIRC7 not yet defined\", \"Whether the T-cell phenotype contributes to osteopetrosis pathology unknown\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"How TIRC7 inhibits T cell activation mechanistically was unknown; epistasis experiments showed that TIRC7 promotes early CTLA-4 surface expression, the two proteins colocalize in clathrin-coated vesicles, and TIRC7-mediated inhibition requires intact CTLA-4, placing TIRC7 upstream of CTLA-4 in the co-inhibitory pathway.\",\n      \"evidence\": \"Immunofluorescence colocalization; CTLA-4 antibody blockade; CTLA-4-deficient splenocyte experiments\",\n      \"pmids\": [\"17082597\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct physical interaction between TIRC7 and CTLA-4 not demonstrated\", \"Molecular basis of CTLA-4 mobilization by TIRC7 unclear\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"The ligand for TIRC7 and its proximal signaling events were unknown; HLA-DRα2 was identified as a direct binding partner that delivers negative signals recruiting SHP-1, suppressing phosphorylation of ZAP70, TCR-ζ, and STAT4, and inducing apoptosis via the intrinsic pathway.\",\n      \"evidence\": \"Pulldown, co-localization at APC–T cell contacts, SHP-1 recruitment assay, phospho-signaling assays, apoptosis assay\",\n      \"pmids\": [\"18270567\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure of the TIRC7–HLA-DRα2 interface unresolved\", \"Whether SHP-1 directly dephosphorylates TCR-ζ/ZAP70 or acts indirectly not tested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Whether TCIRG1 gene transfer could functionally correct patient osteoclasts was untested; lentiviral delivery of TCIRG1 cDNA into patient CD34⁺ cells restored bone resorption to 70–80% of normal, establishing proof-of-concept for gene therapy of TCIRG1-dependent osteopetrosis.\",\n      \"evidence\": \"Lentiviral transduction of patient CD34⁺ cells; Ca²⁺ release, CTX-I ELISA, pit assay; NSG mouse engraftment\",\n      \"pmids\": [\"23907031\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Long-term in vivo engraftment and correction not demonstrated\", \"Optimal vector design for clinical translation undefined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Whether TCIRG1 loss affected bone matrix quality beyond resorption was unknown; genotype-specific histological analysis revealed that TCIRG1 mutations uniquely cause severe osteoid accumulation and decreased calcium content (osteomalacia), separating this from CLCN7 or TNFRSF11A mutation phenotypes.\",\n      \"evidence\": \"Undecalcified iliac crest biopsy histology and calcium content analysis across genotyped osteopetrosis subtypes\",\n      \"pmids\": [\"24108692\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the mineralization defect is secondary to impaired acidification or an independent function of a3 unknown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"How TCIRG1 expression is controlled at the protein level was unclear; studies revealed that TCIRG1 protein accumulates only in mature osteoclasts despite constitutive mRNA expression, and that specific exon-encoded domains (exons 5–6) are essential for V-ATPase function as demonstrated by yeast complementation.\",\n      \"evidence\": \"Lentiviral vector expression at different differentiation stages; codon optimization analysis; yeast Vph1p complementation assay\",\n      \"pmids\": [\"27541021\", \"31111556\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Identity of factors controlling post-transcriptional regulation unknown\", \"Structure–function mapping of the N-terminal cytoplasmic domain incomplete\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Whether TCIRG1 influences osteoclast fusion and differentiation signaling beyond its proton-pumping role was unresolved; knockdown revealed that Tcirg1 promotes large osteoclast formation by sustaining IP3R2 expression and intracellular calcium levels required for NFATc1 nuclear translocation during RANKL-induced osteoclastogenesis.\",\n      \"evidence\": \"Lentiviral shRNA knockdown in bone marrow monocytes; NFATc1/IP3R2 expression; calcium imaging; nuclear translocation assay\",\n      \"pmids\": [\"32790690\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether IP3R2 regulation is direct or secondary to acidification defect not tested\", \"Single lab, not independently confirmed\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Whether osteoclast dysfunction from Tcirg1 loss impacts neighboring non-osteoclast cell types was unknown; in Atp6i⁻/⁻ mice, failure to release TGF-β1 from bone matrix impaired Smad2/3 signaling in odontoblasts, arresting tooth root formation, and ectopic TGF-β1 partially rescued the phenotype, placing Tcirg1-dependent resorption upstream of paracrine growth factor signaling.\",\n      \"evidence\": \"Atp6i⁻/⁻ mouse; RNA-seq; Smad2/3 phosphorylation; TGF-β1 neutralization; kidney capsule transplant rescue\",\n      \"pmids\": [\"37599332\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether other resorption-released growth factors are similarly affected not examined\", \"Relevance to human dental phenotype not confirmed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Whether TCIRG1 controls lysosomal positioning during osteoclast activation and whether heterozygous mutations affect myeloid lineage beyond osteoclasts were open questions; new studies showed that Tcirg1 loss impairs lysosome acidification and peripheral lysosome accumulation during resorption, and that heterozygous TCIRG1 missense mutations cause congenital neutropenia correctable by CRISPR repair.\",\n      \"evidence\": \"Tcirg1-KO OA mouse model with lysosome distribution assays; iPSC-derived neutrophil differentiation with CRISPR/Cas9 correction of R736C\",\n      \"pmids\": [\"40995561\", \"40964614\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking a3 to peripheral lysosome trafficking not defined\", \"Whether heterozygous mutations cause neutropenia via V-ATPase assembly defects versus dominant-negative effects unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The structural basis of a3-subunit integration into V₀ and its isoform-specific targeting to ruffled border versus lysosomes remains undefined; the molecular mechanism by which TIRC7 mobilizes CTLA-4 to the cell surface and the physiological interplay between the osteoclast and T-cell isoforms in vivo have not been resolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of human a3 in the V₀ complex\", \"Mechanism of isoform-specific membrane targeting unresolved\", \"Whether TIRC7 immune function contributes to osteopetrosis clinical phenotype unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [1, 2, 3, 12]},\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [1, 2, 12]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [7, 8, 9]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 2, 3]},\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [20]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [8, 21]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [1, 2, 12]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [7, 8, 9]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [19]}\n    ],\n    \"complexes\": [\n      \"V-ATPase (V₀ sector)\"\n    ],\n    \"partners\": [\n      \"VMA21\",\n      \"CTLA4\",\n      \"HLA-DRA\",\n      \"PTPN6\",\n      \"NFATC1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}