{"gene":"OSR2","run_date":"2026-06-10T05:19:53","timeline":{"discoveries":[{"year":2004,"finding":"Targeted null mutation of Osr2 in mice causes reduced palatal mesenchyme proliferation specifically in the medial halves of downward-growing palatal shelves at E13.5, resulting in cleft palate. Osr2 loss also alters expression of Osr1, Pax9, and Tgfb3 in the developing palate, identifying Osr2 as a key intrinsic regulator of palatal shelf growth and patterning.","method":"Targeted null mutation (gene knockout) in mice with histological and molecular marker analyses (in situ hybridization for Osr1, Pax9, Tgfb3)","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with defined cellular proliferation phenotype and multiple molecular markers, replicated in subsequent studies","pmids":["15175245"],"is_preprint":false},{"year":2009,"finding":"Osr2-deficient mice develop supernumerary teeth lingual to molars due to expansion of the odontogenic field. Osr2 is expressed in a lingual-to-buccal gradient and restricts expression of Bmp4 in the developing tooth mesenchyme. Expansion of the odontogenic field in Osr2-deficient mice requires Msx1 (a feedback activator of Bmp4), placing Osr2 as an antagonist of the Bmp4-Msx1 pathway in tooth field patterning.","method":"Genetic knockout mice, in situ hybridization for Bmp4, double-mutant (Osr2-/-; Msx1-/-) epistasis analysis","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO phenotype, molecular marker analysis, and genetic epistasis in double mutants, independently corroborated by follow-up studies","pmids":["19251632"],"is_preprint":false},{"year":2011,"finding":"Osr2 forms stable protein complexes with the Msx1 transcription factor and interacts weakly with Pax9 in co-transfected cells. Osr2 acts downstream of Pax9 in the tooth mesenchyme, and its expression from the Pax9 locus (knockin) is sufficient to suppress supernumerary tooth formation in Osr2-/- mice. Endogenous Osr2 mRNA expression is significantly downregulated in Pax9-null tooth mesenchyme.","method":"Co-transfection and protein complex assay (co-IP) in cells; Pax9-Osr2 knockin mouse strain; in situ hybridization","journal":"Developmental biology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — protein interaction shown by co-IP in co-transfected cells (single lab), supported by genetic rescue experiments in vivo","pmids":["21420399"],"is_preprint":false},{"year":2011,"finding":"Osr1 and Osr2 function redundantly to control synovial joint formation in mice. Tissue-specific inactivation of Osr1 in the limb mesenchyme of Osr2-/- mice causes fusion of multiple joints. Osr1/Osr2 are required to maintain expression of Gdf5, Wnt4, and Wnt9b in joint cells, and joint cells in double mutants fail to upregulate the articular cartilage marker Prg4.","method":"Conditional double knockout mice (limb-specific Osr1 deletion in Osr2-/- background), in situ hybridization for Gdf5, Wnt4, Wnt9b, Prg4","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean double-KO genetic epistasis with defined joint fusion phenotype and multiple molecular markers","pmids":["21262216"],"is_preprint":false},{"year":2009,"finding":"Osr1 protein can functionally substitute for Osr2 in palate and cranial skeletal development when expressed from the Osr2 locus (knockin), demonstrating that Osr1 and Osr2 have equivalent biochemical activities. The distinct in vivo functions of Osr1 and Osr2 arise from evolutionary divergence of their cis-regulatory sequences rather than differences in protein function. Osr2 controls eyelid development through regulation of the Fgf10-Fgfr2 signaling pathway.","method":"Knockin mouse strains (Osr1 cDNA or Osr2A cDNA replacing endogenous Osr2 coding region); molecular marker analysis for Fgf10 expression","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockin rescue with multiple readouts demonstrates functional equivalence and identifies Fgf10-Fgfr2 as downstream pathway","pmids":["19389375"],"is_preprint":false},{"year":2012,"finding":"In Xenopus, Osr1 and Osr2 act as zinc-finger transcriptional repressors that suppress Bmp4 expression in the foregut lateral plate mesoderm. This repression is required for Wnt2/Wnt2b-mediated lung specification. FGF and RA signals are required upstream for robust osr1/osr2 expression; depletion of both Osr genes results in lung, trachea, and esophagus agenesis and failure to specify Nkx2.1+ progenitors.","method":"Morpholino knockdown of Osr1/Osr2 in Xenopus embryos; epistasis with BMP and Wnt pathway manipulation; in situ hybridization for wnt2, wnt2b, raldh2, Nkx2.1","journal":"Development (Cambridge, England)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — morpholino loss-of-function with epistasis in Xenopus, single lab, multiple pathway markers","pmids":["22791896"],"is_preprint":false},{"year":2013,"finding":"Pax9 regulates a molecular network upstream of Osr2 in the palatal mesenchyme; Bmp4, Fgf10, Msx1, and Osr2 expression are significantly downregulated in Pax9-null palatal mesenchyme. Critically, knockin restoration of Osr2 expression in the early palatal mesenchyme from the Pax9 locus (Pax9Osr2KI) rescues posterior palate morphogenesis in the absence of Pax9, placing Osr2 genetically downstream of Pax9. Pax9 also affects Shh expression in palatal epithelium, indicating a role in mesenchyme-epithelium interactions.","method":"Pax9 conditional knockout; Pax9Osr2KI knockin allele rescue experiment; in situ hybridization for Shh, Bmp4, Fgf10, Msx1, Osr2","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis via knockin rescue, multiple orthogonal molecular markers, defines pathway position of Osr2","pmids":["24173808"],"is_preprint":false},{"year":2016,"finding":"Bmp4-Msx1 signaling and Osr2 have opposite effects on expression of secreted Wnt antagonists (Dkk2, Sfrp2) in the tooth bud mesenchyme. Osr2-dependent preferential expression of Dkk2 and Sfrp2 on the lingual side of the tooth bud mesenchyme was demonstrated by RNA-seq and ISH. Pharmacological activation of canonical Wnt signaling (LiCl or DKK inhibition) rescues mandibular molar morphogenesis in Bmp4ncko/ncko mice, revealing that Bmp4-Msx1 and Osr2 control tooth organogenesis through antagonistic regulation of Wnt antagonist expression.","method":"RNA-seq of tooth mesenchyme from mutant and wildtype embryos; in situ hybridization; in utero pharmacological treatment (LiCl, DKK inhibitors); genetic inactivation of Sfrp2/Sfrp3 in Msx1-/- background","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — RNA-seq, ISH, pharmacological rescue, and genetic epistasis across multiple mutant backgrounds in a single rigorous study","pmids":["27713059"],"is_preprint":false},{"year":2017,"finding":"Osr2 directly binds to the promoter regions of Sema3a and Sema3d genes in embryonic palatal mesenchyme (shown by chromatin immunoprecipitation). Osr2 expression represses transcription from Sema3a and Sema3d promoters in co-transfected cells. Osr2-/- embryos show significantly increased and expanded expression of osteogenic pathway genes (Bmp3, Bmp5, Bmp7, Mef2c, Sox6, Sp7) and ectopic activation of Sema3a, Sema3d, and Sema3e in palatal mesenchyme.","method":"RNA-seq of palatal mesenchyme; chromatin immunoprecipitation (ChIP) followed by RT-PCR; co-transfection transcriptional repression assay; quantitative RT-PCR and in situ hybridization validation","journal":"Journal of dental research","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — ChIP demonstrating direct promoter binding plus co-transfection transcriptional assay plus RNA-seq, multiple orthogonal methods in single lab","pmids":["28731788"],"is_preprint":false},{"year":2024,"finding":"Osr2 expression is selectively induced in terminally exhausted tumor-specific CD8+ T cells by coupled TCR signaling and biomechanical stress via the Piezo1/calcium/CREB axis. Osr2 recruits HDAC3 to rewire the epigenetic program, suppressing cytotoxic gene expression and promoting CD8+ T cell exhaustion. Depletion of Osr2 alleviates exhaustion of tumor-specific CD8+ T cells and CAR-T cells, while forced Osr2 expression aggravates exhaustion in solid tumor models.","method":"Genetic depletion and forced overexpression of Osr2 in CD8+ T cells in solid tumor mouse models; identification of Piezo1/calcium/CREB induction axis; Osr2-HDAC3 interaction assay; epigenetic reprogramming analysis","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function and gain-of-function experiments, identification of upstream induction pathway and downstream HDAC3 recruitment mechanism, published in high-impact journal with multiple orthogonal approaches","pmids":["38744281"],"is_preprint":false},{"year":2015,"finding":"Runx2 expression is expanded in the tooth bud mesenchyme in Osr2-/- embryos. In Osr2-/-Runx2-/- compound mutants, mandibular and maxillary molar tooth germs progress to the early bell stage with rescued Msx1 and Bmp4 expression in the dental papilla, partially rescuing the Runx2-/- developmental arrest phenotype. However, Fgf3 and Fgf10 expression in the dental papilla remained absent and cell proliferation was significantly deficient, showing Runx2 controls continued tooth growth beyond the cap stage through Fgf3 and Fgf10.","method":"Osr2-/-Runx2-/- double mutant mice; in situ hybridization for Runx2, Msx1, Bmp4, Fgf3, Fgf10, Shh, p21; cell proliferation analysis","journal":"Journal of dental research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with double-KO mice and multiple molecular markers, single lab","pmids":["25916343"],"is_preprint":false},{"year":2022,"finding":"MAX directly targets the OSR2 promoter (shown by ChIP-seq and CUT&RUN-seq) and activates OSR2 transcription (validated by dual-luciferase reporter assay). MAX knockdown impairs human endometrial stromal cell decidualization, and OSR2 knockdown phenocopies this defect. OSR2 overexpression can partially rescue IGFBP1 expression (a decidualization marker) in MAX-knockdown cells.","method":"ChIP-seq and CUT&RUN-seq for MAX; dual-luciferase reporter assay for MAX→OSR2 transcriptional activation; RNA-seq; siRNA knockdown of OSR2 and MAX; OSR2 overexpression rescue","journal":"Cell and tissue research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP-seq plus reporter assay demonstrate direct transcriptional regulation, knockdown and rescue functional experiments, single lab","pmids":["35146559"],"is_preprint":false},{"year":2025,"finding":"SOX8 activates OSR2 transcription (identified by RNA-seq, GTRD analysis, and validated by dual-luciferase reporter assays). OSR2 knockdown negates the inhibitory effects of SOX8 overexpression on osteogenic differentiation of ligament fibroblasts, placing OSR2 downstream of SOX8 in the TRIM25/SOX8/OSR2 axis regulating ectopic ossification.","method":"RNA-seq; GTRD transcription factor binding analysis; dual-luciferase reporter assay; OSR2 siRNA knockdown; SOX8 overexpression/knockdown rescue experiments; ALP/Alizarin Red staining for osteogenic differentiation","journal":"JOR spine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reporter assay and genetic epistasis (rescue experiments), multiple orthogonal methods, single lab","pmids":["40918640"],"is_preprint":false},{"year":2025,"finding":"Heterozygous loss-of-function variants in OSR2 (including a 383-kb deletion, two nonsense variants, and two missense variants) cause radioulnar synostosis and ancillary skeletal malformations in humans. Functional studies show that missense variants impair nuclear localization of the OSR2 protein (demonstrated by immunofluorescence) and nonsense variants produce absent or truncated protein (Western blot), confirming loss-of-function mechanisms.","method":"Chromosomal microarray, exome sequencing; Western blot; immunofluorescence for nuclear localization; structural modeling","journal":"Genetics in medicine : official journal of the American College of Medical Genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Western blot and immunofluorescence functional validation of variants, multiple families, single study","pmids":["41424369"],"is_preprint":false},{"year":2001,"finding":"The Osr2 gene encodes a zinc-finger protein related to Drosophila Odd-skipped. The OSR2 protein shares 65% amino acid sequence identity overall and 98% identity in the zinc finger region with OSR1. Osr2 is expressed at sites of epithelial-mesenchymal interactions during tooth, kidney, palate, limb, and craniofacial development.","method":"Gene cloning, sequence analysis, and in situ hybridization expression profiling during mouse embryogenesis","journal":"Mechanisms of development","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — protein characterization by sequence analysis and expression mapping, foundational gene identification, independently replicated","pmids":["11520675"],"is_preprint":false}],"current_model":"OSR2 is a zinc-finger transcriptional repressor (and in some contexts activator) that acts downstream of Pax9 and upstream of BMP4/Msx1 signaling to pattern tooth development and palate morphogenesis, directly binding the promoters of Sema3a and Sema3d; it functions redundantly with OSR1 to maintain synovial joint formation via Gdf5/Wnt4/Wnt9b signaling; it regulates eyelid development through the Fgf10-Fgfr2 pathway; it is transcriptionally activated by MAX and SOX8; and in CD8+ T cells it is induced by Piezo1/calcium/CREB-mediated biomechanical stress, whereupon it recruits HDAC3 to suppress cytotoxic gene expression and promote terminal T cell exhaustion."},"narrative":{"mechanistic_narrative":"OSR2 encodes an Odd-skipped-related zinc-finger transcription factor that functions predominantly as a sequence-specific repressor at sites of epithelial-mesenchymal interaction during craniofacial, skeletal, and visceral organogenesis [PMID:11520675, PMID:28731788]. In tooth development it is expressed in a lingual-to-buccal gradient and restricts the odontogenic field by antagonizing the Bmp4-Msx1 pathway, an epistatic relationship established by the supernumerary-tooth phenotype of Osr2-null mice and its Msx1-dependence [PMID:19251632]; this antagonism is enacted through opposing control of secreted Wnt antagonists (Dkk2, Sfrp2) across the tooth bud mesenchyme [PMID:27713059]. OSR2 acts genetically downstream of Pax9, with which it forms protein complexes alongside Msx1, and knockin expression of Osr2 from the Pax9 locus rescues both palate morphogenesis and supernumerary teeth in the respective mutants [PMID:21420399, PMID:24173808]. In the palate, Osr2 loss reduces medial mesenchyme proliferation to cause cleft palate and de-represses semaphorin and osteogenic programs, including direct binding and repression of the Sema3a and Sema3d promoters [PMID:15175245, PMID:28731788]. OSR2 is functionally redundant and biochemically equivalent to OSR1, the two acting together to maintain synovial joint formation via Gdf5/Wnt4/Wnt9b, with their distinct in vivo roles arising from divergent cis-regulation rather than protein function [PMID:21262216, PMID:19389375]. Beyond development, OSR2 is induced in tumor-specific CD8+ T cells by Piezo1/calcium/CREB biomechanical signaling and recruits HDAC3 to suppress cytotoxic genes and drive terminal exhaustion [PMID:38744281]. Heterozygous loss-of-function OSR2 variants cause radioulnar synostosis and skeletal malformations in humans, with missense alleles disrupting nuclear localization [PMID:41424369].","teleology":[{"year":2001,"claim":"Establishing the molecular identity of OSR2 was the first step: defining it as an Odd-skipped-related zinc-finger protein expressed at epithelial-mesenchymal interfaces framed all subsequent functional work.","evidence":"gene cloning, sequence analysis, and in situ expression profiling in mouse embryos","pmids":["11520675"],"confidence":"Medium","gaps":["DNA-binding specificity not defined","no direct target genes identified at this stage"]},{"year":2004,"claim":"The first loss-of-function model answered whether OSR2 is required for morphogenesis, showing it intrinsically drives medial palatal mesenchyme proliferation and patterns the palate.","evidence":"targeted null mutation in mice with histology and in situ markers (Osr1, Pax9, Tgfb3)","pmids":["15175245"],"confidence":"High","gaps":["direct transcriptional targets in the palate not identified","mechanism linking Osr2 to proliferation unresolved"]},{"year":2009,"claim":"Tooth and eyelid studies clarified OSR2's developmental logic, defining it as an antagonist of the Bmp4-Msx1 pathway that confines the odontogenic field and a regulator of Fgf10-Fgfr2 in eyelid formation.","evidence":"knockout mice, Bmp4 in situ, Osr2-/-;Msx1-/- epistasis; Osr1/Osr2A knockin rescue with Fgf10 markers","pmids":["19251632","19389375"],"confidence":"High","gaps":["whether Bmp4 repression is direct not shown","Osr1/Osr2 equivalence is biochemical inference, not in vitro DNA-binding comparison"]},{"year":2011,"claim":"Placement of OSR2 within signaling hierarchies advanced when it was shown to sit downstream of Pax9 (forming complexes with Msx1) and to act redundantly with Osr1 in joint formation.","evidence":"co-IP in co-transfected cells and Pax9-Osr2 knockin rescue; limb-specific Osr1 deletion in Osr2-/- with Gdf5/Wnt4/Wnt9b/Prg4 markers","pmids":["21420399","21262216"],"confidence":"Medium","gaps":["Osr2-Msx1 interaction shown only by co-IP in transfected cells","no reciprocal endogenous validation of the complex"]},{"year":2013,"claim":"A knockin rescue formalized OSR2 as a critical effector of Pax9, demonstrating restored Osr2 expression alone can rescue posterior palate morphogenesis in Pax9-null embryos.","evidence":"Pax9 conditional knockout and Pax9Osr2KI rescue with Shh/Bmp4/Fgf10/Msx1 in situ","pmids":["24173808"],"confidence":"High","gaps":["mechanism by which Pax9 activates Osr2 not defined","anterior palate not rescued, implying additional Pax9 effectors"]},{"year":2015,"claim":"Compound mutant analysis positioned OSR2 relative to Runx2, showing Osr2 loss expands Runx2 and that removing Runx2 partially rescues Osr2-related tooth defects while Runx2 independently drives Fgf3/Fgf10-dependent growth.","evidence":"Osr2-/-Runx2-/- double mutant mice with multiple in situ markers and proliferation analysis","pmids":["25916343"],"confidence":"Medium","gaps":["whether Osr2 directly represses Runx2 not established","single-lab epistasis"]},{"year":2016,"claim":"The molecular output of the Osr2/Bmp4-Msx1 antagonism was resolved as opposing control of secreted Wnt antagonists, integrating tooth patterning around canonical Wnt signaling.","evidence":"RNA-seq, ISH, in utero LiCl/DKK-inhibitor rescue, and genetic epistasis across mutant backgrounds","pmids":["27713059"],"confidence":"High","gaps":["whether Osr2 directly binds Dkk2/Sfrp2 promoters not shown here"]},{"year":2017,"claim":"Direct target identification confirmed OSR2 as a transcriptional repressor, binding and silencing the Sema3a/Sema3d promoters and restraining osteogenic programs in palatal mesenchyme.","evidence":"palatal mesenchyme RNA-seq, ChIP-PCR, and co-transfection repression assays","pmids":["28731788"],"confidence":"High","gaps":["consensus binding motif not defined","co-repressor machinery in palate not identified"]},{"year":2022,"claim":"Upstream transcriptional control of OSR2 in a non-developmental context emerged with the demonstration that MAX directly activates OSR2 to support endometrial stromal decidualization.","evidence":"ChIP-seq/CUT&RUN, dual-luciferase reporter, siRNA knockdown, and OSR2 rescue in human cells","pmids":["35146559"],"confidence":"Medium","gaps":["OSR2 downstream targets in decidualization not mapped","single-lab human cell-line data"]},{"year":2024,"claim":"A mechanistically distinct immune role was uncovered: biomechanical stress via Piezo1/calcium/CREB induces OSR2, which recruits HDAC3 to epigenetically suppress cytotoxicity and enforce CD8+ T cell exhaustion.","evidence":"loss- and gain-of-function in CD8+/CAR-T cells in solid tumor models with induction-axis and HDAC3-interaction assays","pmids":["38744281"],"confidence":"High","gaps":["direct OSR2-bound exhaustion loci not enumerated","structural basis of OSR2-HDAC3 interaction unknown"]},{"year":2025,"claim":"Human genetics and an additional upstream regulator extended OSR2 biology, establishing it as a haploinsufficient skeletal-malformation gene and a SOX8 effector in ectopic ossification.","evidence":"exome/microarray with Western blot and nuclear-localization immunofluorescence; SOX8 reporter assays and OSR2 knockdown rescue in ligament fibroblasts","pmids":["41424369","40918640"],"confidence":"Medium","gaps":["genotype-phenotype mechanism for radioulnar synostosis not resolved at target-gene level","SOX8/OSR2 axis based on single-lab in vitro rescue"]},{"year":null,"claim":"The OSR2 DNA-binding consensus and the co-repressor complexes it assembles across its developmental and immune contexts remain to be unified into a single mechanistic model.","evidence":"","pmids":[],"confidence":"Medium","gaps":["no defined consensus binding motif across tissues","whether HDAC3 recruitment operates in developmental contexts is untested","structural data on the zinc-finger DNA interface absent"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[8,14]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[8,1,5]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[13]}],"pathway":[{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[0,1,3,6]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[8,9]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[9]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[9]}],"complexes":[],"partners":["MSX1","PAX9","HDAC3","OSR1","MAX","SOX8"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8N2R0","full_name":"Protein odd-skipped-related 2","aliases":[],"length_aa":312,"mass_kda":35.5,"function":"May be involved in the development of the mandibular molar tooth germ at the bud stage","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q8N2R0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/OSR2","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/OSR2","total_profiled":1310},"omim":[{"mim_id":"611297","title":"ODD-SKIPPED-RELATED TRANSCRIPTION FACTOR 2; OSR2","url":"https://www.omim.org/entry/611297"},{"mim_id":"608996","title":"PREMATURE OVARIAN FAILURE 3; POF3","url":"https://www.omim.org/entry/608996"},{"mim_id":"608891","title":"ODD-SKIPPED-RELATED TRANSCRIPTION FACTOR 1; OSR1","url":"https://www.omim.org/entry/608891"},{"mim_id":"605597","title":"FORKHEAD TRANSCRIPTION FACTOR FOXL2; FOXL2","url":"https://www.omim.org/entry/605597"},{"mim_id":"142983","title":"MSH HOMEOBOX 1; MSX1","url":"https://www.omim.org/entry/142983"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Plasma membrane","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"cervix","ntpm":149.8},{"tissue":"endometrium 1","ntpm":161.9},{"tissue":"fallopian tube","ntpm":151.8}],"url":"https://www.proteinatlas.org/search/OSR2"},"hgnc":{"alias_symbol":["FLJ90037"],"prev_symbol":[]},"alphafold":{"accession":"Q8N2R0","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8N2R0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8N2R0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8N2R0-F1-predicted_aligned_error_v6.png","plddt_mean":60.66},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=OSR2","jax_strain_url":"https://www.jax.org/strain/search?query=OSR2"},"sequence":{"accession":"Q8N2R0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8N2R0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8N2R0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8N2R0"}},"corpus_meta":[{"pmid":"15175245","id":"PMC_15175245","title":"Odd-skipped related 2 (Osr2) encodes a key intrinsic regulator of secondary palate growth and morphogenesis.","date":"2004","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/15175245","citation_count":139,"is_preprint":false},{"pmid":"38744281","id":"PMC_38744281","title":"Osr2 functions as a biomechanical checkpoint to aggravate CD8+ T cell exhaustion in tumor.","date":"2024","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/38744281","citation_count":133,"is_preprint":false},{"pmid":"19251632","id":"PMC_19251632","title":"Antagonistic actions of Msx1 and Osr2 pattern mammalian teeth into a single row.","date":"2009","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/19251632","citation_count":98,"is_preprint":false},{"pmid":"11520675","id":"PMC_11520675","title":"Osr2, a new mouse gene related to Drosophila odd-skipped, exhibits dynamic expression patterns during craniofacial, limb, and kidney development.","date":"2001","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/11520675","citation_count":91,"is_preprint":false},{"pmid":"24173808","id":"PMC_24173808","title":"Pax9 regulates a molecular network involving Bmp4, Fgf10, Shh signaling and the Osr2 transcription factor to control palate morphogenesis.","date":"2013","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/24173808","citation_count":84,"is_preprint":false},{"pmid":"22791896","id":"PMC_22791896","title":"Suppression of Bmp4 signaling by the zinc-finger repressors Osr1 and Osr2 is required for Wnt/β-catenin-mediated lung specification in Xenopus.","date":"2012","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/22791896","citation_count":46,"is_preprint":false},{"pmid":"21262216","id":"PMC_21262216","title":"The zinc finger transcription factors Osr1 and Osr2 control synovial joint formation.","date":"2011","source":"Developmental 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biology","url":"https://pubmed.ncbi.nlm.nih.gov/21420399","citation_count":37,"is_preprint":false},{"pmid":"19389375","id":"PMC_19389375","title":"Functional equivalence of the zinc finger transcription factors Osr1 and Osr2 in mouse development.","date":"2009","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/19389375","citation_count":33,"is_preprint":false},{"pmid":"28731788","id":"PMC_28731788","title":"Identification of Osr2 Transcriptional Target Genes in Palate Development.","date":"2017","source":"Journal of dental research","url":"https://pubmed.ncbi.nlm.nih.gov/28731788","citation_count":28,"is_preprint":false},{"pmid":"22129829","id":"PMC_22129829","title":"The Osr1 and Osr2 genes act in the pronephric anlage downstream of retinoic acid signaling and upstream of Wnt2b to maintain pectoral fin development.","date":"2011","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/22129829","citation_count":26,"is_preprint":false},{"pmid":"21281489","id":"PMC_21281489","title":"The nephrogenic potential of the transcription factors osr1, osr2, hnf1b, lhx1 and pax8 assessed in Xenopus animal caps.","date":"2011","source":"BMC developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/21281489","citation_count":25,"is_preprint":false},{"pmid":"27143812","id":"PMC_27143812","title":"Detection of OSR2, VAV3, and PPFIA3 Methylation in the Serum of Patients with Gastric Cancer.","date":"2016","source":"Disease markers","url":"https://pubmed.ncbi.nlm.nih.gov/27143812","citation_count":21,"is_preprint":false},{"pmid":"35146559","id":"PMC_35146559","title":"MAX deficiency impairs human endometrial decidualization through down-regulating OSR2 in women with recurrent spontaneous abortion.","date":"2022","source":"Cell and tissue research","url":"https://pubmed.ncbi.nlm.nih.gov/35146559","citation_count":20,"is_preprint":false},{"pmid":"23238298","id":"PMC_23238298","title":"The odd-skipped related genes Osr1 and Osr2 are induced by 1,25-dihydroxyvitamin D3.","date":"2012","source":"The Journal of steroid biochemistry and molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/23238298","citation_count":11,"is_preprint":false},{"pmid":"25916343","id":"PMC_25916343","title":"Deletion of Osr2 Partially Rescues Tooth Development in Runx2 Mutant Mice.","date":"2015","source":"Journal of dental research","url":"https://pubmed.ncbi.nlm.nih.gov/25916343","citation_count":11,"is_preprint":false},{"pmid":"40067293","id":"PMC_40067293","title":"Long Non-Coding RNA Osr2 Promotes Fusarium solani Keratitis Inflammation via the miR-30a-3p/ Xcr1 Axis.","date":"2025","source":"Investigative ophthalmology & visual science","url":"https://pubmed.ncbi.nlm.nih.gov/40067293","citation_count":2,"is_preprint":false},{"pmid":"40918640","id":"PMC_40918640","title":"TRIM25-Mediated Ubiquitination and Degradation of SOX8 Promotes Ligament Fibroblast Osteogenic Differentiation and Regulates OPLL Progression by Inhibiting OSR2 Transcription.","date":"2025","source":"JOR spine","url":"https://pubmed.ncbi.nlm.nih.gov/40918640","citation_count":0,"is_preprint":false},{"pmid":"41424369","id":"PMC_41424369","title":"Heterozygous loss of OSR2 can cause radioulnar synostosis with ancillary skeletal manifestations.","date":"2025","source":"Genetics in medicine : official journal of the American College of Medical Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/41424369","citation_count":0,"is_preprint":false},{"pmid":"42112349","id":"PMC_42112349","title":"Pan-cancer analysis of OSR2 with a focus on underlying mechanisms and therapeutic implications in lung adenocarcinoma.","date":"2026","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/42112349","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":13458,"output_tokens":4617,"usd":0.054815,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12565,"output_tokens":3800,"usd":0.078912,"stage2_stop_reason":"end_turn"},"total_usd":0.133727,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2004,\n      \"finding\": \"Targeted null mutation of Osr2 in mice causes reduced palatal mesenchyme proliferation specifically in the medial halves of downward-growing palatal shelves at E13.5, resulting in cleft palate. Osr2 loss also alters expression of Osr1, Pax9, and Tgfb3 in the developing palate, identifying Osr2 as a key intrinsic regulator of palatal shelf growth and patterning.\",\n      \"method\": \"Targeted null mutation (gene knockout) in mice with histological and molecular marker analyses (in situ hybridization for Osr1, Pax9, Tgfb3)\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with defined cellular proliferation phenotype and multiple molecular markers, replicated in subsequent studies\",\n      \"pmids\": [\"15175245\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Osr2-deficient mice develop supernumerary teeth lingual to molars due to expansion of the odontogenic field. Osr2 is expressed in a lingual-to-buccal gradient and restricts expression of Bmp4 in the developing tooth mesenchyme. Expansion of the odontogenic field in Osr2-deficient mice requires Msx1 (a feedback activator of Bmp4), placing Osr2 as an antagonist of the Bmp4-Msx1 pathway in tooth field patterning.\",\n      \"method\": \"Genetic knockout mice, in situ hybridization for Bmp4, double-mutant (Osr2-/-; Msx1-/-) epistasis analysis\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO phenotype, molecular marker analysis, and genetic epistasis in double mutants, independently corroborated by follow-up studies\",\n      \"pmids\": [\"19251632\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Osr2 forms stable protein complexes with the Msx1 transcription factor and interacts weakly with Pax9 in co-transfected cells. Osr2 acts downstream of Pax9 in the tooth mesenchyme, and its expression from the Pax9 locus (knockin) is sufficient to suppress supernumerary tooth formation in Osr2-/- mice. Endogenous Osr2 mRNA expression is significantly downregulated in Pax9-null tooth mesenchyme.\",\n      \"method\": \"Co-transfection and protein complex assay (co-IP) in cells; Pax9-Osr2 knockin mouse strain; in situ hybridization\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — protein interaction shown by co-IP in co-transfected cells (single lab), supported by genetic rescue experiments in vivo\",\n      \"pmids\": [\"21420399\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Osr1 and Osr2 function redundantly to control synovial joint formation in mice. Tissue-specific inactivation of Osr1 in the limb mesenchyme of Osr2-/- mice causes fusion of multiple joints. Osr1/Osr2 are required to maintain expression of Gdf5, Wnt4, and Wnt9b in joint cells, and joint cells in double mutants fail to upregulate the articular cartilage marker Prg4.\",\n      \"method\": \"Conditional double knockout mice (limb-specific Osr1 deletion in Osr2-/- background), in situ hybridization for Gdf5, Wnt4, Wnt9b, Prg4\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean double-KO genetic epistasis with defined joint fusion phenotype and multiple molecular markers\",\n      \"pmids\": [\"21262216\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Osr1 protein can functionally substitute for Osr2 in palate and cranial skeletal development when expressed from the Osr2 locus (knockin), demonstrating that Osr1 and Osr2 have equivalent biochemical activities. The distinct in vivo functions of Osr1 and Osr2 arise from evolutionary divergence of their cis-regulatory sequences rather than differences in protein function. Osr2 controls eyelid development through regulation of the Fgf10-Fgfr2 signaling pathway.\",\n      \"method\": \"Knockin mouse strains (Osr1 cDNA or Osr2A cDNA replacing endogenous Osr2 coding region); molecular marker analysis for Fgf10 expression\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockin rescue with multiple readouts demonstrates functional equivalence and identifies Fgf10-Fgfr2 as downstream pathway\",\n      \"pmids\": [\"19389375\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In Xenopus, Osr1 and Osr2 act as zinc-finger transcriptional repressors that suppress Bmp4 expression in the foregut lateral plate mesoderm. This repression is required for Wnt2/Wnt2b-mediated lung specification. FGF and RA signals are required upstream for robust osr1/osr2 expression; depletion of both Osr genes results in lung, trachea, and esophagus agenesis and failure to specify Nkx2.1+ progenitors.\",\n      \"method\": \"Morpholino knockdown of Osr1/Osr2 in Xenopus embryos; epistasis with BMP and Wnt pathway manipulation; in situ hybridization for wnt2, wnt2b, raldh2, Nkx2.1\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — morpholino loss-of-function with epistasis in Xenopus, single lab, multiple pathway markers\",\n      \"pmids\": [\"22791896\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Pax9 regulates a molecular network upstream of Osr2 in the palatal mesenchyme; Bmp4, Fgf10, Msx1, and Osr2 expression are significantly downregulated in Pax9-null palatal mesenchyme. Critically, knockin restoration of Osr2 expression in the early palatal mesenchyme from the Pax9 locus (Pax9Osr2KI) rescues posterior palate morphogenesis in the absence of Pax9, placing Osr2 genetically downstream of Pax9. Pax9 also affects Shh expression in palatal epithelium, indicating a role in mesenchyme-epithelium interactions.\",\n      \"method\": \"Pax9 conditional knockout; Pax9Osr2KI knockin allele rescue experiment; in situ hybridization for Shh, Bmp4, Fgf10, Msx1, Osr2\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis via knockin rescue, multiple orthogonal molecular markers, defines pathway position of Osr2\",\n      \"pmids\": [\"24173808\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Bmp4-Msx1 signaling and Osr2 have opposite effects on expression of secreted Wnt antagonists (Dkk2, Sfrp2) in the tooth bud mesenchyme. Osr2-dependent preferential expression of Dkk2 and Sfrp2 on the lingual side of the tooth bud mesenchyme was demonstrated by RNA-seq and ISH. Pharmacological activation of canonical Wnt signaling (LiCl or DKK inhibition) rescues mandibular molar morphogenesis in Bmp4ncko/ncko mice, revealing that Bmp4-Msx1 and Osr2 control tooth organogenesis through antagonistic regulation of Wnt antagonist expression.\",\n      \"method\": \"RNA-seq of tooth mesenchyme from mutant and wildtype embryos; in situ hybridization; in utero pharmacological treatment (LiCl, DKK inhibitors); genetic inactivation of Sfrp2/Sfrp3 in Msx1-/- background\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — RNA-seq, ISH, pharmacological rescue, and genetic epistasis across multiple mutant backgrounds in a single rigorous study\",\n      \"pmids\": [\"27713059\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Osr2 directly binds to the promoter regions of Sema3a and Sema3d genes in embryonic palatal mesenchyme (shown by chromatin immunoprecipitation). Osr2 expression represses transcription from Sema3a and Sema3d promoters in co-transfected cells. Osr2-/- embryos show significantly increased and expanded expression of osteogenic pathway genes (Bmp3, Bmp5, Bmp7, Mef2c, Sox6, Sp7) and ectopic activation of Sema3a, Sema3d, and Sema3e in palatal mesenchyme.\",\n      \"method\": \"RNA-seq of palatal mesenchyme; chromatin immunoprecipitation (ChIP) followed by RT-PCR; co-transfection transcriptional repression assay; quantitative RT-PCR and in situ hybridization validation\",\n      \"journal\": \"Journal of dental research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — ChIP demonstrating direct promoter binding plus co-transfection transcriptional assay plus RNA-seq, multiple orthogonal methods in single lab\",\n      \"pmids\": [\"28731788\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Osr2 expression is selectively induced in terminally exhausted tumor-specific CD8+ T cells by coupled TCR signaling and biomechanical stress via the Piezo1/calcium/CREB axis. Osr2 recruits HDAC3 to rewire the epigenetic program, suppressing cytotoxic gene expression and promoting CD8+ T cell exhaustion. Depletion of Osr2 alleviates exhaustion of tumor-specific CD8+ T cells and CAR-T cells, while forced Osr2 expression aggravates exhaustion in solid tumor models.\",\n      \"method\": \"Genetic depletion and forced overexpression of Osr2 in CD8+ T cells in solid tumor mouse models; identification of Piezo1/calcium/CREB induction axis; Osr2-HDAC3 interaction assay; epigenetic reprogramming analysis\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function and gain-of-function experiments, identification of upstream induction pathway and downstream HDAC3 recruitment mechanism, published in high-impact journal with multiple orthogonal approaches\",\n      \"pmids\": [\"38744281\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Runx2 expression is expanded in the tooth bud mesenchyme in Osr2-/- embryos. In Osr2-/-Runx2-/- compound mutants, mandibular and maxillary molar tooth germs progress to the early bell stage with rescued Msx1 and Bmp4 expression in the dental papilla, partially rescuing the Runx2-/- developmental arrest phenotype. However, Fgf3 and Fgf10 expression in the dental papilla remained absent and cell proliferation was significantly deficient, showing Runx2 controls continued tooth growth beyond the cap stage through Fgf3 and Fgf10.\",\n      \"method\": \"Osr2-/-Runx2-/- double mutant mice; in situ hybridization for Runx2, Msx1, Bmp4, Fgf3, Fgf10, Shh, p21; cell proliferation analysis\",\n      \"journal\": \"Journal of dental research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with double-KO mice and multiple molecular markers, single lab\",\n      \"pmids\": [\"25916343\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"MAX directly targets the OSR2 promoter (shown by ChIP-seq and CUT&RUN-seq) and activates OSR2 transcription (validated by dual-luciferase reporter assay). MAX knockdown impairs human endometrial stromal cell decidualization, and OSR2 knockdown phenocopies this defect. OSR2 overexpression can partially rescue IGFBP1 expression (a decidualization marker) in MAX-knockdown cells.\",\n      \"method\": \"ChIP-seq and CUT&RUN-seq for MAX; dual-luciferase reporter assay for MAX→OSR2 transcriptional activation; RNA-seq; siRNA knockdown of OSR2 and MAX; OSR2 overexpression rescue\",\n      \"journal\": \"Cell and tissue research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP-seq plus reporter assay demonstrate direct transcriptional regulation, knockdown and rescue functional experiments, single lab\",\n      \"pmids\": [\"35146559\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SOX8 activates OSR2 transcription (identified by RNA-seq, GTRD analysis, and validated by dual-luciferase reporter assays). OSR2 knockdown negates the inhibitory effects of SOX8 overexpression on osteogenic differentiation of ligament fibroblasts, placing OSR2 downstream of SOX8 in the TRIM25/SOX8/OSR2 axis regulating ectopic ossification.\",\n      \"method\": \"RNA-seq; GTRD transcription factor binding analysis; dual-luciferase reporter assay; OSR2 siRNA knockdown; SOX8 overexpression/knockdown rescue experiments; ALP/Alizarin Red staining for osteogenic differentiation\",\n      \"journal\": \"JOR spine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reporter assay and genetic epistasis (rescue experiments), multiple orthogonal methods, single lab\",\n      \"pmids\": [\"40918640\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Heterozygous loss-of-function variants in OSR2 (including a 383-kb deletion, two nonsense variants, and two missense variants) cause radioulnar synostosis and ancillary skeletal malformations in humans. Functional studies show that missense variants impair nuclear localization of the OSR2 protein (demonstrated by immunofluorescence) and nonsense variants produce absent or truncated protein (Western blot), confirming loss-of-function mechanisms.\",\n      \"method\": \"Chromosomal microarray, exome sequencing; Western blot; immunofluorescence for nuclear localization; structural modeling\",\n      \"journal\": \"Genetics in medicine : official journal of the American College of Medical Genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Western blot and immunofluorescence functional validation of variants, multiple families, single study\",\n      \"pmids\": [\"41424369\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"The Osr2 gene encodes a zinc-finger protein related to Drosophila Odd-skipped. The OSR2 protein shares 65% amino acid sequence identity overall and 98% identity in the zinc finger region with OSR1. Osr2 is expressed at sites of epithelial-mesenchymal interactions during tooth, kidney, palate, limb, and craniofacial development.\",\n      \"method\": \"Gene cloning, sequence analysis, and in situ hybridization expression profiling during mouse embryogenesis\",\n      \"journal\": \"Mechanisms of development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — protein characterization by sequence analysis and expression mapping, foundational gene identification, independently replicated\",\n      \"pmids\": [\"11520675\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"OSR2 is a zinc-finger transcriptional repressor (and in some contexts activator) that acts downstream of Pax9 and upstream of BMP4/Msx1 signaling to pattern tooth development and palate morphogenesis, directly binding the promoters of Sema3a and Sema3d; it functions redundantly with OSR1 to maintain synovial joint formation via Gdf5/Wnt4/Wnt9b signaling; it regulates eyelid development through the Fgf10-Fgfr2 pathway; it is transcriptionally activated by MAX and SOX8; and in CD8+ T cells it is induced by Piezo1/calcium/CREB-mediated biomechanical stress, whereupon it recruits HDAC3 to suppress cytotoxic gene expression and promote terminal T cell exhaustion.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"OSR2 encodes an Odd-skipped-related zinc-finger transcription factor that functions predominantly as a sequence-specific repressor at sites of epithelial-mesenchymal interaction during craniofacial, skeletal, and visceral organogenesis [#14, #8]. In tooth development it is expressed in a lingual-to-buccal gradient and restricts the odontogenic field by antagonizing the Bmp4-Msx1 pathway, an epistatic relationship established by the supernumerary-tooth phenotype of Osr2-null mice and its Msx1-dependence [#1]; this antagonism is enacted through opposing control of secreted Wnt antagonists (Dkk2, Sfrp2) across the tooth bud mesenchyme [#7]. OSR2 acts genetically downstream of Pax9, with which it forms protein complexes alongside Msx1, and knockin expression of Osr2 from the Pax9 locus rescues both palate morphogenesis and supernumerary teeth in the respective mutants [#2, #6]. In the palate, Osr2 loss reduces medial mesenchyme proliferation to cause cleft palate and de-represses semaphorin and osteogenic programs, including direct binding and repression of the Sema3a and Sema3d promoters [#0, #8]. OSR2 is functionally redundant and biochemically equivalent to OSR1, the two acting together to maintain synovial joint formation via Gdf5/Wnt4/Wnt9b, with their distinct in vivo roles arising from divergent cis-regulation rather than protein function [#3, #4]. Beyond development, OSR2 is induced in tumor-specific CD8+ T cells by Piezo1/calcium/CREB biomechanical signaling and recruits HDAC3 to suppress cytotoxic genes and drive terminal exhaustion [#9]. Heterozygous loss-of-function OSR2 variants cause radioulnar synostosis and skeletal malformations in humans, with missense alleles disrupting nuclear localization [#13].\",\n  \"teleology\": [\n    {\n      \"year\": 2001,\n      \"claim\": \"Establishing the molecular identity of OSR2 was the first step: defining it as an Odd-skipped-related zinc-finger protein expressed at epithelial-mesenchymal interfaces framed all subsequent functional work.\",\n      \"evidence\": \"gene cloning, sequence analysis, and in situ expression profiling in mouse embryos\",\n      \"pmids\": [\"11520675\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"DNA-binding specificity not defined\", \"no direct target genes identified at this stage\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"The first loss-of-function model answered whether OSR2 is required for morphogenesis, showing it intrinsically drives medial palatal mesenchyme proliferation and patterns the palate.\",\n      \"evidence\": \"targeted null mutation in mice with histology and in situ markers (Osr1, Pax9, Tgfb3)\",\n      \"pmids\": [\"15175245\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"direct transcriptional targets in the palate not identified\", \"mechanism linking Osr2 to proliferation unresolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Tooth and eyelid studies clarified OSR2's developmental logic, defining it as an antagonist of the Bmp4-Msx1 pathway that confines the odontogenic field and a regulator of Fgf10-Fgfr2 in eyelid formation.\",\n      \"evidence\": \"knockout mice, Bmp4 in situ, Osr2-/-;Msx1-/- epistasis; Osr1/Osr2A knockin rescue with Fgf10 markers\",\n      \"pmids\": [\"19251632\", \"19389375\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"whether Bmp4 repression is direct not shown\", \"Osr1/Osr2 equivalence is biochemical inference, not in vitro DNA-binding comparison\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Placement of OSR2 within signaling hierarchies advanced when it was shown to sit downstream of Pax9 (forming complexes with Msx1) and to act redundantly with Osr1 in joint formation.\",\n      \"evidence\": \"co-IP in co-transfected cells and Pax9-Osr2 knockin rescue; limb-specific Osr1 deletion in Osr2-/- with Gdf5/Wnt4/Wnt9b/Prg4 markers\",\n      \"pmids\": [\"21420399\", \"21262216\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Osr2-Msx1 interaction shown only by co-IP in transfected cells\", \"no reciprocal endogenous validation of the complex\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"A knockin rescue formalized OSR2 as a critical effector of Pax9, demonstrating restored Osr2 expression alone can rescue posterior palate morphogenesis in Pax9-null embryos.\",\n      \"evidence\": \"Pax9 conditional knockout and Pax9Osr2KI rescue with Shh/Bmp4/Fgf10/Msx1 in situ\",\n      \"pmids\": [\"24173808\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"mechanism by which Pax9 activates Osr2 not defined\", \"anterior palate not rescued, implying additional Pax9 effectors\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Compound mutant analysis positioned OSR2 relative to Runx2, showing Osr2 loss expands Runx2 and that removing Runx2 partially rescues Osr2-related tooth defects while Runx2 independently drives Fgf3/Fgf10-dependent growth.\",\n      \"evidence\": \"Osr2-/-Runx2-/- double mutant mice with multiple in situ markers and proliferation analysis\",\n      \"pmids\": [\"25916343\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"whether Osr2 directly represses Runx2 not established\", \"single-lab epistasis\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"The molecular output of the Osr2/Bmp4-Msx1 antagonism was resolved as opposing control of secreted Wnt antagonists, integrating tooth patterning around canonical Wnt signaling.\",\n      \"evidence\": \"RNA-seq, ISH, in utero LiCl/DKK-inhibitor rescue, and genetic epistasis across mutant backgrounds\",\n      \"pmids\": [\"27713059\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"whether Osr2 directly binds Dkk2/Sfrp2 promoters not shown here\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Direct target identification confirmed OSR2 as a transcriptional repressor, binding and silencing the Sema3a/Sema3d promoters and restraining osteogenic programs in palatal mesenchyme.\",\n      \"evidence\": \"palatal mesenchyme RNA-seq, ChIP-PCR, and co-transfection repression assays\",\n      \"pmids\": [\"28731788\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"consensus binding motif not defined\", \"co-repressor machinery in palate not identified\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Upstream transcriptional control of OSR2 in a non-developmental context emerged with the demonstration that MAX directly activates OSR2 to support endometrial stromal decidualization.\",\n      \"evidence\": \"ChIP-seq/CUT&RUN, dual-luciferase reporter, siRNA knockdown, and OSR2 rescue in human cells\",\n      \"pmids\": [\"35146559\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"OSR2 downstream targets in decidualization not mapped\", \"single-lab human cell-line data\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"A mechanistically distinct immune role was uncovered: biomechanical stress via Piezo1/calcium/CREB induces OSR2, which recruits HDAC3 to epigenetically suppress cytotoxicity and enforce CD8+ T cell exhaustion.\",\n      \"evidence\": \"loss- and gain-of-function in CD8+/CAR-T cells in solid tumor models with induction-axis and HDAC3-interaction assays\",\n      \"pmids\": [\"38744281\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"direct OSR2-bound exhaustion loci not enumerated\", \"structural basis of OSR2-HDAC3 interaction unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Human genetics and an additional upstream regulator extended OSR2 biology, establishing it as a haploinsufficient skeletal-malformation gene and a SOX8 effector in ectopic ossification.\",\n      \"evidence\": \"exome/microarray with Western blot and nuclear-localization immunofluorescence; SOX8 reporter assays and OSR2 knockdown rescue in ligament fibroblasts\",\n      \"pmids\": [\"41424369\", \"40918640\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"genotype-phenotype mechanism for radioulnar synostosis not resolved at target-gene level\", \"SOX8/OSR2 axis based on single-lab in vitro rescue\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The OSR2 DNA-binding consensus and the co-repressor complexes it assembles across its developmental and immune contexts remain to be unified into a single mechanistic model.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"no defined consensus binding motif across tissues\", \"whether HDAC3 recruitment operates in developmental contexts is untested\", \"structural data on the zinc-finger DNA interface absent\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [8, 14]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [8, 1, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [13]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [0, 1, 3, 6]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [8, 9]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [9]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [9]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"MSX1\", \"PAX9\", \"HDAC3\", \"OSR1\", \"MAX\", \"SOX8\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}