{"gene":"SMAD3","run_date":"2026-06-10T07:46:35","timeline":{"discoveries":[{"year":1997,"finding":"SMAD3 (and SMAD2) interact with the kinase-deficient TGF-β type I receptor (TβR-I) after it is phosphorylated by TβR-II kinase; TGF-β1 induces phosphorylation of SMAD3; upon TβR activation, SMAD3 forms heteromeric complexes with SMAD2 and SMAD4; these complexes translocate to the nucleus and synergistically activate TGF-β-inducible transcription (PAI-1 promoter). Dominant-negative SMAD3 inhibited the synergistic transcriptional response.","method":"Co-immunoprecipitation in COS cells, phosphorylation assays in Mv1Lu and HSC4 cells, nuclear translocation imaging, transcriptional reporter assay","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, phosphorylation assays, nuclear translocation, reporter assays, replicated across cell lines and multiple labs subsequently","pmids":["9311995"],"is_preprint":false},{"year":2002,"finding":"SARA (Smad Anchor for Receptor Activation) specifically recognizes monomeric SMAD3, while the transcriptional co-repressor Ski specifically recognizes trimeric SMAD3. Phosphorylation-induced trimerization of SMAD3 simultaneously drives dissociation from SARA (activating TGF-β signal) and sets up Ski-mediated negative feedback. Structural models of SMAD3/SARA/receptor kinase and SMAD3/Ski complexes were generated.","method":"Structural modeling, biochemical binding assays distinguishing monomeric vs. trimeric SMAD3, in vitro reconstitution","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1 / Moderate — structural modeling with functional biochemical validation, mechanistically clear allosteric mechanism, single lab but multiple orthogonal approaches","pmids":["12154125"],"is_preprint":false},{"year":2005,"finding":"ERK MAP kinase phosphorylates SMAD3 at Ser207, Ser203, and Thr178 in the linker region upon EGF treatment. Phosphorylation peaks at 15–30 min, is blocked by MEK1 inhibitors, and is recapitulated by recombinant ERK2 in vitro. Mutation of these ERK sites increases SMAD3 transcriptional activity on a Smad target gene, indicating ERK phosphorylation inhibits SMAD3 activity.","method":"Phosphopeptide mapping, in vitro kinase assay with recombinant ERK2, site-directed mutagenesis, transcriptional reporter assay","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay with mutagenesis and transcriptional readout, single lab with multiple orthogonal methods","pmids":["16156666"],"is_preprint":false},{"year":2006,"finding":"Non-activated SMAD3 (but not SMAD2) undergoes proteasome-dependent degradation mediated by scaffolding protein Axin and its associated kinase GSK3-β. SMAD3 physically interacts with Axin and GSK3-β only in the absence of TGF-β. GSK3-β phosphorylates SMAD3 at Thr66, triggering SMAD3 ubiquitination and degradation. Thr66 mutants show altered protein stability and transcriptional activity.","method":"Co-immunoprecipitation, proteasome inhibitor assays, in vitro phosphorylation, site-directed mutagenesis of Thr66, transcriptional reporter assay","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro phosphorylation with mutagenesis, Co-IP, ubiquitination assay, functional reporter assay; multiple orthogonal methods in single rigorous study","pmids":["18172167"],"is_preprint":false},{"year":2006,"finding":"SMAD3 DNA binding activity is enhanced by acetylation of Lys19 in the MH1 domain, mediated by coactivators p300 and CBP in a TGF-β-dependent manner. Acetylation of Lys19 induces a conformational change making the MH1 DNA-binding domain accessible. Acetyl-Lys19-specific antibodies confirmed endogenous SMAD3 acetylation in response to TGF-β.","method":"In vitro acetylation assay with p300/CBP, site-directed mutagenesis, acetyl-Lys19 antibody, DNA-binding assay, ChIP on target promoters","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro acetylation with mutagenesis, antibody validation, ChIP, DNA-binding assays; multiple orthogonal methods","pmids":["17074756"],"is_preprint":false},{"year":2009,"finding":"Under hypoxic conditions, protein phosphatase 2A (PP2A) specifically dephosphorylates SMAD3 (but not SMAD2). PP2A physically interacts with SMAD3 only under hypoxia, and Smad3-associated PP2A activity is detectable under these conditions. The scaffold subunit PR65 is required for this hypoxic dephosphorylation. Hypoxia attenuates nuclear accumulation of TGF-β-induced SMAD3 and SMAD3-activated gene expression, which is reversed by chemical PP2A inhibition.","method":"Co-immunoprecipitation, PP2A activity assay, nuclear translocation assay, gene expression analysis, pharmacological PP2A inhibition","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, phosphatase activity assay, nuclear localization experiments, pharmacological rescue; multiple orthogonal methods single lab","pmids":["19951945"],"is_preprint":false},{"year":2001,"finding":"SMAD3 specifically represses androgen receptor (AR)-mediated transcription on two natural androgen-responsive promoters. A direct protein-protein interaction between AR and SMAD3 was identified in vitro and in vivo; the transcription activation domain of AR binds the MH2 domain of SMAD3, and the repression of AR is mediated solely through the MH2 domain of SMAD3.","method":"Transient transfection reporter assays, GST pulldown (in vitro binding), co-immunoprecipitation (in vivo), domain-mapping mutagenesis","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — GST pulldown + Co-IP + domain mutagenesis + functional reporter assay; multiple orthogonal methods, single lab","pmids":["11280774"],"is_preprint":false},{"year":2002,"finding":"BRCA2 forms a complex with SMAD3 in vitro and in vivo; both MH1 and MH2 domains of SMAD3 contribute to the interaction. TGF-β1 stimulates interaction of endogenous SMAD3 and BRCA2 in non-transfected cells. BRCA2 co-activates SMAD3-dependent transcriptional activation of PAI-1 and a luciferase reporter, and SMAD3 increases BRCA2 transcriptional activity.","method":"GST pulldown, co-immunoprecipitation of endogenous proteins, luciferase reporter assay, domain mapping","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP (including endogenous), GST pulldown, reporter assays; single lab","pmids":["12165866"],"is_preprint":false},{"year":2005,"finding":"SMAD3 (via its MH1 domain) forms a complex with BRCA1 in vitro and in vivo, and they co-localize in nuclear complexes. TGF-β1/SMAD3 counteracts BRCA1-dependent repair of DNA double-strand breaks, as measured by BRCA1 nuclear foci formation, single-cell gel electrophoresis, and cell survival assays.","method":"GST pulldown, co-immunoprecipitation, confocal co-localization, comet assay, colony survival assay, BRCA1 nuclear foci analysis","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP + pulldown + comet assay + functional survival readout; single lab, multiple orthogonal methods","pmids":["15735739"],"is_preprint":false},{"year":2008,"finding":"FoxL2 directly associates with SMAD3 (but not SMAD2 or SMAD4) through its MH2 domain, and this interaction requires an intact forkhead domain in FoxL2. FoxL2 and SMAD3 are both recruited to the intronic Smad-binding element (SBE1) of the follistatin gene enhancer (confirmed by ChIP) and cooperate to drive activin/SMAD3-mediated follistatin transcription. shRNA knockdown of FoxL2 impairs SBE1-mediated transcription.","method":"Co-immunoprecipitation, chromatin immunoprecipitation (ChIP), luciferase reporter assay, shRNA knockdown, domain-mapping mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — Co-IP, ChIP, reporter assay, shRNA rescue; multiple orthogonal methods, single lab","pmids":["19106105"],"is_preprint":false},{"year":2010,"finding":"SMAD3 directly binds to the miR-192 promoter and mediates TGF-β1-induced miR-192 expression specifically (not SMAD2). miR-192 in turn promotes collagen matrix expression downstream of TGF-β/SMAD3 signaling in renal fibrosis.","method":"Smad3-selective knockdown/overexpression, promoter binding assay (ChIP), miR-192 mimic/inhibitor functional assays, collagen matrix assays","journal":"Journal of the American Society of Nephrology : JASN","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP demonstrating SMAD3 promoter occupancy, Smad2 vs Smad3 specificity tested, functional mimic/inhibitor experiments; single lab","pmids":["20488955"],"is_preprint":false},{"year":2010,"finding":"Smad2 deletion enhances TGF-β/SMAD3 signaling, increasing SMAD3 phosphorylation, nuclear translocation, promoter activity, and binding of SMAD3 to the COL1A2 collagen promoter (by ChIP). Conversely, overexpression of SMAD2 attenuates TGF-β1-induced SMAD3 phosphorylation. This identifies SMAD2 as a counterbalancing regulator of SMAD3 signaling.","method":"Conditional Smad2 knockout (renal tubular epithelial cells), ChIP on COL1A2 promoter, SMAD3 phosphorylation Western blot, nuclear translocation assay, promoter reporter assay","journal":"Journal of the American Society of Nephrology : JASN","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic deletion (in vivo and in vitro), ChIP, phosphorylation assays, nuclear localization; multiple orthogonal methods, replicated in fibroblasts","pmids":["20595680"],"is_preprint":false},{"year":2011,"finding":"TRB3 (TRIB3) is a novel SMAD3-interacting protein; the kinase-like domain of TRB3 interacts with the MH2 domain of SMAD3. TRB3 enhances SMAD3 transcriptional activity, promotes nuclear localization of SMAD3 via MH2-domain interaction, and stabilizes phospho-SMAD3 by triggering degradation of Smurf2 (the SMAD ubiquitin regulatory factor 2). TGF-β1 stimulation or SMAD3 overexpression induces TRB3 expression, creating a positive feedback loop.","method":"Co-immunoprecipitation, domain-mapping mutagenesis, reporter assay, subcellular localization imaging, siRNA knockdown, Western blot for Smurf2/SMAD2/pSMAD3 levels","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with domain mapping, nuclear localization imaging, Smurf2 degradation functional assay; single lab, multiple methods","pmids":["21896644"],"is_preprint":false},{"year":2011,"finding":"SMAD3 directly binds to a SMAD-binding element (SBE) in the promoter region of miR-200b/a (confirmed by luciferase reporter with SBE mutagenesis) and functions as a transcriptional activator of miR-200 family members, which in turn suppress ZEB1/ZEB2 and regulate E-cadherin. This regulation occurs independently of TGF-β.","method":"Luciferase reporter assay with SBE mutagenesis, SMAD3 overexpression/silencing, miRNA profiling, ChIP (implied by binding element analysis)","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reporter assay with mutagenesis, SMAD3-specific knockdown/overexpression; single lab","pmids":["22020340"],"is_preprint":false},{"year":2012,"finding":"Activated STAT3 directly interacts with SMAD3 in vivo and in vitro, resulting in attenuation of SMAD3-SMAD4 complex formation and suppression of SMAD3 DNA-binding ability. The N-terminal region of the STAT3 DNA-binding domain is responsible for the STAT3-SMAD3 interaction and required for STAT3-mediated inhibition of TGF-β signaling.","method":"Co-immunoprecipitation in vivo and in vitro, domain mapping, SMAD3-SMAD4 complex formation assay, SMAD3 DNA-binding assay, STAT3 knockdown with TGF-β response readouts","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP + domain mapping + DNA-binding assay + knockdown functional assays; single lab","pmids":["26616859"],"is_preprint":false},{"year":2013,"finding":"SMAD3 physically interacts with tendon transcriptional regulators Scleraxis and Mohawk (by Co-IP). Loss of Smad3 in mice reduces collagen 1 and Tenascin-C protein expression, disrupts tendon architecture, and downregulates key tendon marker genes in developing and adult tendon.","method":"Co-immunoprecipitation, Smad3-/- mouse model, histology, gene/protein expression analysis","journal":"Journal of orthopaedic research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP of endogenous proteins + genetic KO with phenotypic readout; single lab","pmids":["23653374"],"is_preprint":false},{"year":2013,"finding":"SMAD3 expression is sufficient (via in vivo plasmid transfection) to stimulate atrogin-1 promoter activity, inhibit Akt/mTOR signaling and protein synthesis, and induce muscle fiber atrophy. SMAD3 also inhibits PGC1α promoter activity and increases FoxO-mediated signaling and PAI-1 promoter activity. Mechanistically, SMAD3-induced decrease in miR-29 leads to increased PTEN translation, inhibiting Akt/mTOR.","method":"In vivo muscle transfection (transient transgenic), atrogin-1/PGC1α/PAI-1 promoter reporter assays, Akt/mTOR signaling Western blots, miR-29/PTEN assays","journal":"Molecular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo gain-of-function with multiple downstream readouts; single lab, single publication","pmids":["24002653"],"is_preprint":false},{"year":2013,"finding":"WWOX protein physically interacts with SMAD3 via its WW domain 1. WWOX expression reduces SMAD3 occupancy at ANGPTL4 and SERPINE1 promoters (by ChIP), quenches TGF-β-responsive reporter activation, and causes redistribution of SMAD3 from the nuclear to the cytoplasmic compartment.","method":"Co-immunoprecipitation, GST pulldown, ChIP, luciferase reporter assay, confocal microscopy for SMAD3 localization, shRNA knockdown","journal":"BMC cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP + GST pulldown + ChIP + reporter assay + localization; single lab, multiple orthogonal methods","pmids":["24330518"],"is_preprint":false},{"year":2015,"finding":"Autocrine TGF-β-SMAD3 transcription factor signal (but not SMAD2) is necessary for robust TGF-β expression in dendritic cells activated by Clostridium butyricum, while SMAD2 negatively regulates TGF-β expression. This establishes that SMAD2 and SMAD3 inversely regulate TGF-β autoinduction in dendritic cells.","method":"Smad2-deficient and Smad3-deficient dendritic cells, TGF-β reporter assays, cytokine measurement, colitis model","journal":"Immunity","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO of Smad2 vs Smad3 with functional readout, direct comparison; single lab","pmids":["26141582"],"is_preprint":false},{"year":2015,"finding":"PCDH1 (protocadherin-1) binds endogenously to SMAD3 in bronchial epithelial cells (confirmed by Y2H and Co-IP at endogenous levels). PCDH1 overexpression suppresses TGF-β-induced activation of a SMAD3-driven reporter and TGF-β target gene expression, while siRNA knockdown of PCDH1 increases TGF-β-induced SMAD3 transcriptional activity.","method":"Yeast two-hybrid, co-immunoprecipitation at endogenous protein levels, luciferase reporter assay, siRNA knockdown, TGF-β target gene qPCR","journal":"American journal of physiology. Lung cellular and molecular physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — endogenous Co-IP + reporter assay + siRNA/overexpression functional assays; single lab","pmids":["26209277"],"is_preprint":false},{"year":2017,"finding":"OSM (oncostatin M)/STAT3 activation promotes SMAD3 nuclear accumulation and DNA binding in a TGF-β receptor-dependent manner. SMAD3 (but not SMAD2 or SMAD4) is required for OSM/STAT3-mediated epithelial-mesenchymal plasticity and cancer stem cell properties, establishing a STAT3-SMAD3 cooperative signaling axis.","method":"SMAD3/SMAD2/SMAD4 ablation (shRNA/CRISPR), nuclear fractionation, SMAD3-DNA binding assay, SMAD3-dependent transcriptional reporter, cancer stem cell/EMT phenotypic assays","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic ablation of specific SMADs with functional phenotypic readouts + nuclear translocation assay; single lab","pmids":["28288136"],"is_preprint":false},{"year":2017,"finding":"SMAD3 directly suppresses transcription of the NK cell differentiation factor E4BP4/NFIL3 (identified as a direct SMAD3 target gene), thereby inhibiting NK cell development and IFN-γ production. Disruption of SMAD3 in bone marrow expands NK cell population with enhanced tumor-suppressive activity; the SMAD3-E4BP4 axis mediates TGF-β-dependent NK cell immunosuppression.","method":"Smad3-/- bone marrow transplant, ex vivo NK cell differentiation assays, E4BP4 promoter reporter assay/ChIP, Smad3 inhibitor (SIS3) treatment, syngeneic tumor models","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO in vivo + ChIP identifying direct target + pharmacological inhibition + multiple functional readouts; multiple orthogonal methods","pmids":["28262747"],"is_preprint":false},{"year":2018,"finding":"Crystal structure of SMAD3 MH2 domain in complex with transcription factor FOXH1 reveals that the MH2 domain has multiple hydrophobic patches that serve as binding interfaces for different cofactors. SMAD3 and SMAD2 use different subsets of these hydrophobic patches to selectively recruit distinct cofactors (e.g., FOXH1 vs. SKI), explaining cofactor selectivity in TGF-β signaling.","method":"Crystal structure determination (X-ray crystallography) of SMAD3-FOXH1 and SMAD2-SKI complexes","journal":"Science signaling","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structures of SMAD3-cofactor complexes with functional implications for selectivity; single lab but Tier 1 structural method","pmids":["29588413"],"is_preprint":false},{"year":2018,"finding":"KAT5 acetyltransferase is recruited to SMAD3 by TRIB3 adaptor protein and induces phosphorylation-dependent K333 acetylation of SMAD3, which sustains SMAD3 transcriptional activity and promotes TRIB3 transcription (positive feedback loop). Metformin suppresses SMAD3 phosphorylation and decreases the KAT5/SMAD3 interaction, attenuating K333 acetylation and SMAD3-dependent transcription.","method":"Co-immunoprecipitation, in vitro acetylation assay, site-directed mutagenesis (K333), transcriptional reporter assay, metformin treatment in vivo and in vitro","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP + mutagenesis + reporter assay; single lab with multiple orthogonal methods","pmids":["29520103"],"is_preprint":false},{"year":2019,"finding":"Macrophage-specific Smad3 knockout mice exhibit impaired phagocytic activity, defective anti-inflammatory macrophage transition, and adverse cardiac remodeling after myocardial infarction. Phagocytosis directly activates macrophage SMAD3 (independent of TGF-β release). SMAD3-null macrophages show reduced Mfge8 expression (eat-me signal), reduced IL-10 and TGF-β1 production, and attenuated PPAR expression induced by phagocytosis. Mfge8 partially rescues the phagocytic defect.","method":"Myeloid-specific Smad3 conditional knockout mice, myocardial infarction model, phagocytosis assays in vitro, cytokine measurement, Mfge8 rescue experiment","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 2 / Strong — cell-specific genetic KO in vivo + multiple in vitro mechanistic assays + rescue experiment; multiple orthogonal methods","pmids":["31092129"],"is_preprint":false},{"year":2020,"finding":"SMAD3 directly binds to the 3'-UTR of TFEB mRNA and inhibits its transcription (confirmed by ChIP at TFEB 3'-UTR). SMAD3-mediated TFEB suppression inhibits lysosome biogenesis, leading to lysosome depletion and autophagy dysregulation in diabetic nephropathy. Pharmacological inhibition or genetic deletion of SMAD3 restores TFEB expression and lysosome biogenesis.","method":"ChIP demonstrating SMAD3 binding at TFEB 3'-UTR, SMAD3 genetic deletion/inhibition (SIS3), TFEB silencing rescue experiment, lysosome biogenesis assays (LAMP1, autophagic flux)","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP + genetic KO + siRNA rescue; single lab, multiple methods","pmids":["33043774"],"is_preprint":false},{"year":2021,"finding":"SMAD3 binding to fibroblast differentiation gene promoters in macrophage-lineage cells (detected by ChIP-seq) drives macrophage-to-myofibroblast transition (MMT), generating cancer-associated fibroblasts. Macrophage-specific deletion or pharmacological inhibition of SMAD3 blocks MMT and suppresses CAF formation and tumor progression in vivo.","method":"ChIP-seq (SMAD3 binding), macrophage-specific Smad3 conditional KO, adoptive transfer of BMDM-derived MMTs, single-cell RNA-seq, pharmacological inhibition (SIS3), Lewis lung carcinoma model","journal":"Advanced science","confidence":"High","confidence_rationale":"Tier 2 / Strong — ChIP-seq + cell-specific genetic KO + pharmacological inhibition + in vivo functional assays; multiple orthogonal methods","pmids":["34791825"],"is_preprint":false},{"year":2021,"finding":"USP7 deubiquitinase removes mono-ubiquitin from SMAD3 (deubiquitination of SMAD3), which is required for SMAD3 DNA-binding activity. Mono-ubiquitination of SMAD3 negatively regulates its DNA-binding function; USP7-mediated de-monoubiquitination of SMAD3 facilitates SMAD3-SMAD4 dimer binding at the SMAD3 locus super-enhancer, enabling SMAD3 autoregulation.","method":"USP7 CRISPR/Cas9 KO, ChIP-seq and RNA-seq (genome-wide), cell-free and cell-based ubiquitination/deubiquitination assays, SMAD3 autoregulation reporter assay","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP-seq + biochemical deubiquitination assay + CRISPR KO functional readouts; single lab, multiple orthogonal methods","pmids":["34580281"],"is_preprint":false},{"year":2021,"finding":"SO2-derived peroxymonosulfite promotes sulfenylation (cysteine oxidation) of SMAD3 at cysteine-64, inhibiting its DNA-binding activity. Mutation of Cys64 attenuates the protective effects of SO2 on angiotensin II-induced vascular remodeling and hypertension, establishing this redox modification as functionally relevant.","method":"Site-centric chemoproteomics (sulfenylation quantification), site-directed mutagenesis (Cys64), vascular smooth muscle cell assays, angiotensin II hypertension mouse model","journal":"Redox biology","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — chemoproteomic identification of modification site + mutagenesis + in vivo functional rescue; single lab, multiple orthogonal methods","pmids":["33647858"],"is_preprint":false},{"year":2022,"finding":"EZH2 methylates SMAD3 at K53 and K333; this methylation facilitates SMAD3 interaction with its membrane-localization molecule SARA, which in turn sustains SMAD3 phosphorylation by the TGF-β receptor. EZH2-mediated SMAD3 K53/K333 methylation is required for full SMAD3 activation upon TGF-β1 stimulation and promotes tumor metastasis.","method":"In vitro methylation assay with recombinant EZH2, site-directed mutagenesis (K53, K333), Co-IP (SMAD3-SARA interaction), TGF-β receptor phosphorylation assay, breast cancer metastasis xenograft model, TAT peptide therapeutic inhibition","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro methylation reconstitution + mutagenesis + Co-IP of SARA interaction + functional rescue in vivo; multiple orthogonal methods in single rigorous study","pmids":["35085106"],"is_preprint":false},{"year":2022,"finding":"TGF-β/activin-activated SMAD3 (but not SMAD1) promotes SOX2 expression and anchorage-independent survival in ovarian cancer via SMAD3-dependent histone H3K4me3 recruitment at the SOX2 promoter. Conversely, BMP/SMAD1 represses SOX2 through H3K27me3 and DNA methylation.","method":"SMAD3 knockdown/knockout, ChIP for H3K4me3 at SOX2 promoter, gene expression profiling, anchorage-independent survival assays, intraperitoneal tumor burden assays","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP for specific histone marks + genetic manipulation + in vivo functional assays; single lab","pmids":["35905726"],"is_preprint":false},{"year":2022,"finding":"SIRT2 deacetylase directly interacts with and deacetylates SMAD3 at lysine 341 and K378, reducing SMAD3 activation. SMAD3 deacetylation by SIRT2 occurs only in the presence of TGF-β and reduces SMAD3 phosphorylation, nuclear localization, and downstream fibrotic gene expression.","method":"Co-immunoprecipitation, in vitro deacetylation assay, site-directed mutagenesis (K341, K378), SIRT2 conditional KO mice, nuclear localization assays, fibrotic gene expression readouts","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP + in vitro deacetylation + mutagenesis + genetic KO functional assays; single lab","pmids":["37777567"],"is_preprint":false},{"year":2023,"finding":"SMAD3 binds to intron 3 of the AR (androgen receptor) gene to promote AR expression (identified by ChIP-seq; binding sites validated by CRISPRi). Approximately 50% of AR and SMAD3 ChIP-seq peaks overlap, indicating SMAD3 also co-occupies AR target gene loci. SMAD3 knockdown decreases AR levels and AR target gene expression, an effect partially rescued by AR re-expression.","method":"SMAD3 knockdown (siRNA), ChIP-seq (SMAD3 and AR binding), RNA-seq, CRISPRi targeting SMAD3-binding sites in AR intron 3, AR rescue experiments, SMAD3 PROTAC inhibitor","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 / Strong — ChIP-seq + CRISPRi functional validation + RNA-seq + rescue experiments; multiple orthogonal genome-wide and functional methods","pmids":["36727462"],"is_preprint":false},{"year":2023,"finding":"ATOH8 binds SMAD3 to form a transcriptional complex that directly represses cell cycle-promoting genes and induces oncogene-induced senescence (OIS) in lung epithelial cells downstream of Ras overactivation and TGF-β1/SMAD3 signaling. SMAD3 (not SMAD2 or SMAD4) is the determinant mediator of this senescence response. Depletion of ATOH8 accelerates Ras-driven lung tumorigenesis and confers sensitivity to SMAD3 inhibitor.","method":"Co-immunoprecipitation (ATOH8-SMAD3 complex), SMAD3/SMAD2/SMAD4 knockdown specificity assays, transcriptional profiling of repressed cell cycle genes, ATOH8 deletion mouse model, Smad3 inhibitor treatment","journal":"PNAS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP + SMAD-specific knockdown + in vivo KO tumor model + pharmacological rescue; single lab, multiple methods","pmids":["36626550"],"is_preprint":false},{"year":2021,"finding":"Cell intercalation downstream of TGF-β/SMAD3 signaling is required for secondary neural tube formation in vivo. SMAD3 acts with YAP to resolve a centrally positioned lumen through cell intercalation during tail bud development, demonstrated by SMAD3 loss-of-function experiments and live in vivo imaging in chicken embryo.","method":"In vivo SMAD3 loss-of-function (chick embryo electroporation), live imaging of cell intercalation, YAP inhibition assays, lumen formation readout","journal":"Developmental cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo loss-of-function with live imaging readout; single lab, single publication","pmids":["33878300"],"is_preprint":false},{"year":2012,"finding":"Linker-region phosphorylation of SMAD3 (at four sites mutated in the EPSM mutant) negatively regulates SMAD3 transcriptional activity and TGF-β1/SMAD3-induced epithelial-mesenchymal transition in renal epithelial cells. C-terminal SSXS phosphorylation is essential for mediating TGF-β response, while linker phosphorylation acts as a brake.","method":"Site-directed mutagenesis (EPSM and 3S-A SMAD3 mutants), TGF-β1 induction of EMT in Smad3-deficient primary renal cells reconstituted with mutants, Western blot and RT-PCR for EMT markers","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — mutagenesis of phosphorylation sites with functional EMT readout; single lab, clean mechanistic result","pmids":["23022526"],"is_preprint":false},{"year":2013,"finding":"p-Akt physically interacts with SMAD3 in wild-type mouse muscles and C2C12 myoblasts (by co-immunoprecipitation). IGF-I increases p-Akt/SMAD3 interaction (retaining SMAD3 in cytoplasm), while TGF-β1 decreases it, allowing SMAD3 nuclear translocation and fibronectin expression. This p-Akt/SMAD3 interaction constitutes a molecular switch between myogenesis and fibrogenesis.","method":"Co-immunoprecipitation of p-Akt and SMAD3, IGF-I/TGF-β1 treatment, SMAD3 nuclear translocation assay, fibronectin expression, IGF-IR heterozygous KO mouse model","journal":"American journal of physiology. Endocrinology and metabolism","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP demonstrating p-Akt/SMAD3 interaction + nuclear translocation assay + in vivo KO model; single lab","pmids":["23736539"],"is_preprint":false}],"current_model":"SMAD3 is a TGF-β/activin pathway transcription factor that is recruited to the activated TβR-I/II receptor complex via SARA in its monomeric form, phosphorylated at its C-terminal SSXS motif by TβR-I, which drives trimerization, dissociation from SARA, and nuclear translocation with SMAD4; its activity is tightly regulated by phosphorylation (GSK3-β at Thr66 triggers degradation; ERK at Ser203/207/Thr178 inhibits activity; linker phosphorylation acts as a brake; PP2A specifically dephosphorylates it under hypoxia), by acetylation (p300/CBP at Lys19 enhances DNA binding; KAT5 at K333 sustains activity), by methylation (EZH2 at K53/K333 facilitates SARA interaction and receptor phosphorylation), by mono-ubiquitination (inhibits DNA binding, reversed by USP7), and by cysteine sulfenylation (Cys64, inhibits DNA binding); in the nucleus SMAD3 selectively interacts with a wide range of cofactors (FOXH1, SKI, FoxL2, Scleraxis, Mohawk, EGR1, Pitx2, ATOH8, STAT3, AR, BRCA1/2, WWOX, PCDH1, TRB3) through distinct hydrophobic patches on its MH2 domain to drive or repress transcription of target genes including collagen, PAI-1, miR-192, miR-200, E4BP4/NFIL3, TFEB, and AR, thereby orchestrating fibrosis, immune regulation, NK cell development, muscle atrophy, and cancer progression."},"narrative":{"mechanistic_narrative":"SMAD3 is the central signal-transducing transcription factor of the TGF-β/activin pathway, coupling receptor activation at the membrane to gene-regulatory programs that govern fibrosis, immune regulation, cancer progression, and tissue development [PMID:9311995, PMID:28262747, PMID:34791825]. Upon TGF-β stimulation, SMAD3 is recruited to and phosphorylated by the activated TβR-I/II receptor complex, forms heteromeric complexes with SMAD4 (and SMAD2), translocates to the nucleus, and synergistically activates target promoters such as PAI-1 [PMID:9311995]; SARA recognizes monomeric SMAD3 while phosphorylation-driven trimerization simultaneously releases SARA and exposes SMAD3 to Ski-mediated negative feedback [PMID:12154125]. Activation is gated by a dense layer of post-translational modifications: C-terminal SSXS phosphorylation is essential while linker-region phosphorylation acts as a brake [PMID:23022526], ERK phosphorylation at Ser203/Ser207/Thr178 and GSK3-β phosphorylation at Thr66 (driving Axin-dependent proteasomal degradation) restrain activity [PMID:16156666, PMID:18172167], hypoxic PP2A dephosphorylates SMAD3 specifically [PMID:19951945], EZH2 methylation at K53/K333 promotes the SARA interaction and receptor-mediated phosphorylation [PMID:35085106], p300/CBP acetylation at Lys19 and KAT5 acetylation at K333 enhance DNA binding and sustain activity (opposed by SIRT2 deacetylation) [PMID:17074756, PMID:29520103, PMID:37777567], and mono-ubiquitination and Cys64 sulfenylation each inhibit DNA binding, the former reversed by USP7 to enable SMAD3 autoregulation [PMID:34580281, PMID:33647858]. In the nucleus, distinct hydrophobic patches on the SMAD3 MH2 domain confer cofactor selectivity — a crystal structure of the MH2–FOXH1 complex established how SMAD3 versus SMAD2 recruit different partners [PMID:29588413] — allowing SMAD3 to engage a wide range of context-specific cofactors including FoxL2, Scleraxis/Mohawk, ATOH8, STAT3, the androgen receptor, BRCA1/BRCA2, and WWOX to activate or repress transcription [PMID:19106105, PMID:23653374, PMID:36626550, PMID:11280774, PMID:12165866, PMID:15735739, PMID:24330518]. Through these interactions SMAD3 binds defined promoter and enhancer elements to control collagen, PAI-1, miR-192, miR-200, the NK-cell factor E4BP4/NFIL3, TFEB, and AR, thereby driving renal and tendon fibrosis, macrophage-to-myofibroblast transition, muscle atrophy, NK-cell immunosuppression, and EMT/stemness programs [PMID:20488955, PMID:22020340, PMID:28262747, PMID:33043774, PMID:34791825, PMID:24002653, PMID:28288136]. SMAD3 function is consistently distinguished from SMAD2, which acts as a counterbalancing or opposing regulator across renal, immune, and developmental contexts [PMID:20595680, PMID:26141582].","teleology":[{"year":1997,"claim":"Established SMAD3 as a direct receptor-activated effector of TGF-β, answering how an extracellular cytokine signal reaches the nucleus to control transcription.","evidence":"Co-IP, phosphorylation assays, nuclear translocation imaging, and PAI-1 reporter assays across COS, Mv1Lu, and HSC4 cells","pmids":["9311995"],"confidence":"High","gaps":["Did not resolve the structural basis of receptor recognition","Stoichiometry of the SMAD2/3/4 complex left undefined"]},{"year":2001,"claim":"Showed SMAD3 functions not only as an activator but as a direct transcriptional repressor, here of androgen-receptor-mediated transcription, expanding its regulatory repertoire.","evidence":"GST pulldown, Co-IP, and reporter assays mapping the AR activation domain to the SMAD3 MH2 domain","pmids":["11280774"],"confidence":"High","gaps":["Mechanism of repression at native chromatin not defined","Relationship to TGF-β stimulation unclear"]},{"year":2002,"claim":"Defined the allosteric logic linking phosphorylation to signaling state: monomeric SMAD3 binds SARA, trimeric SMAD3 binds Ski, so trimerization both activates and sets up negative feedback.","evidence":"Structural modeling with biochemical binding assays distinguishing monomeric vs. trimeric SMAD3","pmids":["12154125"],"confidence":"High","gaps":["Based on modeling rather than experimental structures of full complexes","Kinetics of the monomer-to-trimer transition not measured"]},{"year":2002,"claim":"Linked SMAD3 to DNA-damage-response machinery by identifying BRCA2 as a bidirectional transcriptional partner.","evidence":"GST pulldown, endogenous Co-IP after TGF-β1, and luciferase reporter assays with domain mapping","pmids":["12165866"],"confidence":"Medium","gaps":["Single lab","Functional consequence at endogenous target genes not established"]},{"year":2005,"claim":"Demonstrated that SMAD3 integrates RTK input, with ERK phosphorylating the linker to inhibit SMAD3 transcriptional output — a crosstalk node between growth-factor and TGF-β signaling.","evidence":"Phosphopeptide mapping, in vitro ERK2 kinase assay, mutagenesis of Ser203/Ser207/Thr178, reporter assay","pmids":["16156666"],"confidence":"High","gaps":["In vivo relevance of each site not dissected","Mechanism by which linker phosphorylation reduces activity unresolved"]},{"year":2005,"claim":"Connected SMAD3 to DNA double-strand-break repair, showing TGF-β/SMAD3 antagonizes BRCA1-dependent repair.","evidence":"GST pulldown, Co-IP, confocal co-localization, comet and colony-survival assays, BRCA1 foci analysis","pmids":["15735739"],"confidence":"Medium","gaps":["Single lab","Direct chromatin mechanism of repair interference not defined"]},{"year":2006,"claim":"Identified SMAD3-specific degradation control, with GSK3-β phosphorylating Thr66 in unstimulated cells to trigger Axin-scaffolded ubiquitin-proteasome turnover.","evidence":"Co-IP, proteasome inhibitor assays, in vitro phosphorylation, Thr66 mutagenesis, reporter assay","pmids":["18172167"],"confidence":"High","gaps":["E3 ligase responsible not identified","Quantitative contribution to basal SMAD3 pool unclear"]},{"year":2006,"claim":"Established acetylation as a positive activating mark, with p300/CBP acetylating Lys19 to expose the MH1 DNA-binding domain.","evidence":"In vitro acetylation assay, Lys19 mutagenesis, acetyl-Lys19 antibody, DNA-binding and ChIP assays","pmids":["17074756"],"confidence":"High","gaps":["Deacetylase counteracting Lys19 not identified here","Interplay with phosphorylation timing not resolved"]},{"year":2008,"claim":"Revealed cofactor-directed promoter selectivity, with FoxL2 recruiting SMAD3 specifically (not SMAD2/4) to the follistatin SBE1 enhancer.","evidence":"Co-IP, ChIP, luciferase reporter, shRNA knockdown, domain mapping requiring the forkhead domain","pmids":["19106105"],"confidence":"High","gaps":["Structural basis of the MH2-forkhead interface not defined","Generality to other forkhead partners untested here"]},{"year":2009,"claim":"Showed SMAD3 signaling is tuned by environmental oxygen, with hypoxia-recruited PP2A specifically dephosphorylating SMAD3 to dampen nuclear accumulation.","evidence":"Co-IP, PP2A activity assay, nuclear translocation and gene-expression analysis, pharmacological PP2A inhibition; PR65 scaffold requirement","pmids":["19951945"],"confidence":"High","gaps":["How hypoxia targets PP2A to SMAD3 specifically not defined","Phospho-sites dephosphorylated not mapped"]},{"year":2010,"claim":"Defined SMAD2 as a counterbalancing regulator of SMAD3 and identified miR-192 as a direct SMAD3 target driving fibrotic collagen output.","evidence":"Conditional Smad2 knockout, ChIP on COL1A2 and miR-192 promoters, phosphorylation and reporter assays, miRNA functional assays","pmids":["20595680","20488955"],"confidence":"High","gaps":["Mechanism by which SMAD2 limits SMAD3 phosphorylation not fully resolved","Direct vs. indirect promoter occupancy at some loci inferred"]},{"year":2011,"claim":"Uncovered positive-feedback partners (TRB3) that stabilize phospho-SMAD3 and identified miR-200 as a TGF-β-independent SMAD3 target controlling EMT regulators.","evidence":"Co-IP and domain mapping, Smurf2 degradation assay, localization imaging; SBE-mutagenesis luciferase reporter and SMAD3 manipulation for miR-200","pmids":["21896644","22020340"],"confidence":"Medium","gaps":["Single labs","ChIP occupancy at miR-200 promoter inferred rather than directly shown"]},{"year":2012,"claim":"Distinguished the functional roles of C-terminal versus linker phosphorylation, showing the SSXS tail is essential for activation while linker phosphorylation acts as a brake on EMT.","evidence":"EPSM and 3S-A SMAD3 mutants reconstituted into Smad3-deficient renal cells with EMT marker readouts","pmids":["23022526"],"confidence":"Medium","gaps":["Kinases acting at each linker site in this context not assigned","Single lab"]},{"year":2013,"claim":"Extended SMAD3's reach into tendon, muscle, and a cytoplasmic myogenesis/fibrogenesis switch, defining tissue-specific cofactors and signaling crosstalk.","evidence":"Co-IP with Scleraxis/Mohawk and Smad3 KO histology; in vivo muscle transfection with atrogin-1/PGC1α readouts and miR-29/PTEN axis; p-Akt/SMAD3 Co-IP with IGF-I/TGF-β1 switching","pmids":["23653374","24002653","23736539"],"confidence":"Medium","gaps":["Single labs per tissue","Direct vs. indirect transcriptional targets in atrophy not all mapped"]},{"year":2013,"claim":"Identified WWOX as a negative regulator that sequesters SMAD3 in the cytoplasm and reduces its promoter occupancy.","evidence":"Co-IP, GST pulldown, ChIP at ANGPTL4/SERPINE1, reporter assay, confocal localization, shRNA","pmids":["24330518"],"confidence":"Medium","gaps":["Single lab","Whether sequestration is direct or via altered phosphorylation unclear"]},{"year":2015,"claim":"Established opposing SMAD2/SMAD3 control of immune programs, with SMAD3 required for TGF-β autoinduction in dendritic cells and engaging a STAT3 interaction that inhibits SMAD3 DNA binding.","evidence":"Smad2/Smad3-deficient dendritic cells with colitis model; reciprocal Co-IP, SMAD3-SMAD4 complex and DNA-binding assays with STAT3 domain mapping","pmids":["26141582","26616859"],"confidence":"Medium","gaps":["Single labs","Context-dependence of STAT3 inhibition vs. cooperation not reconciled here"]},{"year":2015,"claim":"Identified PCDH1 as an endogenous brake on SMAD3 transcriptional activity in airway epithelium.","evidence":"Yeast two-hybrid, endogenous Co-IP, reporter and siRNA/overexpression functional assays with target qPCR","pmids":["26209277"],"confidence":"Medium","gaps":["Single lab","Subcellular mechanism of inhibition not defined"]},{"year":2017,"claim":"Defined SMAD3-specific roles in immune and cancer-stemness programs: direct repression of E4BP4/NFIL3 to suppress NK-cell development, and a cooperative STAT3-SMAD3 axis driving EMP/stemness.","evidence":"Smad3 KO bone marrow with NK differentiation, E4BP4 ChIP/reporter, SIS3 inhibitor, tumor models; SMAD-specific ablation with nuclear fractionation and DNA-binding/phenotypic assays for OSM/STAT3","pmids":["28262747","28288136"],"confidence":"High","gaps":["How STAT3 here promotes vs. elsewhere inhibits SMAD3 DNA binding not reconciled","Direct SMAD3 targets in stemness program not fully enumerated"]},{"year":2018,"claim":"Provided the structural explanation for cofactor selectivity, showing the SMAD3 MH2 domain uses distinct hydrophobic patches to recruit different partners (FOXH1 vs. SKI).","evidence":"X-ray crystal structures of SMAD3-FOXH1 and SMAD2-SKI complexes","pmids":["29588413"],"confidence":"High","gaps":["Structures of additional cofactor complexes not solved","Affinity hierarchy among competing cofactors not measured"]},{"year":2018,"claim":"Added acetylation-based amplification, with TRIB3-recruited KAT5 acetylating K333 to sustain SMAD3 activity in a feedback loop druggable by metformin.","evidence":"Co-IP, in vitro acetylation, K333 mutagenesis, reporter assay, metformin treatment in vitro and in vivo","pmids":["29520103"],"confidence":"Medium","gaps":["Single lab","Interplay between K333 acetylation and K333 methylation not resolved"]},{"year":2019,"claim":"Showed phagocytosis directly activates macrophage SMAD3 independent of TGF-β release, driving anti-inflammatory transition and adaptive cardiac remodeling.","evidence":"Myeloid-specific Smad3 conditional KO, myocardial infarction model, phagocytosis and cytokine assays, Mfge8 rescue","pmids":["31092129"],"confidence":"High","gaps":["Receptor coupling phagocytosis to SMAD3 phosphorylation not identified","Direct vs. indirect control of Mfge8 not shown"]},{"year":2020,"claim":"Linked SMAD3 to autophagy and lysosomal biogenesis by direct repression of TFEB, explaining lysosome depletion in diabetic nephropathy.","evidence":"ChIP at the TFEB 3'-UTR, SMAD3 deletion/SIS3 inhibition, TFEB silencing rescue, lysosome/autophagy flux assays","pmids":["33043774"],"confidence":"Medium","gaps":["Single lab","Mechanism of 3'-UTR-targeted transcriptional repression atypical and not fully explained"]},{"year":2021,"claim":"Established multiple new layers of SMAD3 regulation and output: USP7-mediated de-monoubiquitination enabling DNA binding and autoregulation, Cys64 sulfenylation as a redox off-switch, macrophage-to-myofibroblast transition generating CAFs, and a SMAD3/YAP role in neural tube morphogenesis.","evidence":"USP7 CRISPR KO with ChIP-seq/RNA-seq and ubiquitination assays; chemoproteomics with Cys64 mutagenesis in hypertension model; SMAD3 ChIP-seq with macrophage-specific KO and SIS3 in lung carcinoma; chick-embryo SMAD3 loss-of-function with live imaging","pmids":["34580281","33647858","34791825","33878300"],"confidence":"High","gaps":["E3 ligase depositing the mono-ubiquitin not identified","Enzymatic source of Cys64 sulfenylation in vivo not defined"]},{"year":2022,"claim":"Defined methylation-driven activation and its acetyl/deacetyl counterbalance, plus SMAD3-specific chromatin output: EZH2 K53/K333 methylation promotes SARA binding and receptor phosphorylation, SIRT2 deacetylates K341/K378 to dampen activity, and SMAD3 drives SOX2 via H3K4me3.","evidence":"In vitro methylation/deacetylation reconstitution, site mutagenesis, SARA Co-IP, conditional KO mice, ChIP for histone marks, breast and ovarian cancer models","pmids":["35085106","37777567","35905726"],"confidence":"Medium","gaps":["Combinatorial logic among competing modifications at shared residues (e.g., K333) not resolved","Some findings single-lab"]},{"year":2023,"claim":"Established genome-wide SMAD3 control of the androgen receptor and a SMAD3-ATOH8 senescence program, expanding SMAD3's transcriptional reach in cancer.","evidence":"SMAD3 and AR ChIP-seq with CRISPRi validation, RNA-seq, AR rescue, PROTAC inhibitor; ATOH8-SMAD3 Co-IP, SMAD-specific knockdown, ATOH8 deletion tumor model, SMAD3 inhibitor","pmids":["36727462","36626550"],"confidence":"High","gaps":["How SMAD3 selects activating vs. repressive programs genome-wide not fully defined","Cofactor partition between AR co-occupancy and senescence loci unclear"]},{"year":null,"claim":"How the dozens of competing post-translational modifications (often on shared residues such as K333) and the many context-specific cofactors are integrated to determine whether SMAD3 activates or represses a given locus remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model reconciling competing modifications at shared lysines","Quantitative cofactor competition at the MH2 hydrophobic patches not mapped genome-wide","Determinants of activator vs. repressor mode at individual targets undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,9,10,13,21,25,26,32,33]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[4,14,27,28]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,1]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,5,17,36]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[17,36]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[0,8]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1,22]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,9,21,25,32]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[18,21,24]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[20,26,30,33]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[34,15]}],"complexes":["SMAD3-SMAD4 complex","SMAD3-SMAD2-SMAD4 receptor-activated complex"],"partners":["SMAD4","SMAD2","SARA","FOXH1","STAT3","TRIB3","AR","BRCA1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P84022","full_name":"SMAD family member 3","aliases":["JV15-2","Mothers against decapentaplegic homolog 3","MAD homolog 3","Mad3","Mothers against DPP homolog 3","hMAD-3"],"length_aa":425,"mass_kda":48.1,"function":"Receptor-regulated SMAD (R-SMAD) that is an intracellular signal transducer and transcriptional modulator activated by TGF-beta (transforming growth factor) and activin type 1 receptor kinases. Binds the TRE element in the promoter region of many genes that are regulated by TGF-beta and, on formation of the SMAD3/SMAD4 complex, activates transcription. Also can form a SMAD3/SMAD4/JUN/FOS complex at the AP-1/SMAD site to regulate TGF-beta-mediated transcription. Has an inhibitory effect on wound healing probably by modulating both growth and migration of primary keratinocytes and by altering the TGF-mediated chemotaxis of monocytes. This effect on wound healing appears to be hormone-sensitive. Regulator of chondrogenesis and osteogenesis and inhibits early healing of bone fractures. Positively regulates PDPK1 kinase activity by stimulating its dissociation from the 14-3-3 protein YWHAQ which acts as a negative regulator","subcellular_location":"Cytoplasm; Nucleus","url":"https://www.uniprot.org/uniprotkb/P84022/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SMAD3","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SMAD3","total_profiled":1310},"omim":[{"mim_id":"621375","title":"IMMUNE DYSREGULATION, NEURODEVELOPMENTAL DEFECTS, AND COLITIS; IDNDC","url":"https://www.omim.org/entry/621375"},{"mim_id":"621316","title":"HSP90AB1-ASSOCIATED LONG NONCODING RNA 1; HSALR1","url":"https://www.omim.org/entry/621316"},{"mim_id":"621305","title":"CARDIAC MESODERM ENHANCER-ASSOCIATED NONCODING RNA; CARMN","url":"https://www.omim.org/entry/621305"},{"mim_id":"620847","title":"BONE MORPHOGENETIC PROTEIN 8A; BMP8A","url":"https://www.omim.org/entry/620847"},{"mim_id":"620733","title":"MICRO RNA 708; MIR708","url":"https://www.omim.org/entry/620733"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Vesicles","reliability":"Additional"},{"location":"Primary cilium transition zone","reliability":"Additional"},{"location":"Basal body","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/SMAD3"},"hgnc":{"alias_symbol":["JV15-2","HsT17436"],"prev_symbol":["MADH3"]},"alphafold":{"accession":"P84022","domains":[{"cath_id":"3.90.520.10","chopping":"9-128","consensus_level":"high","plddt":92.9126,"start":9,"end":128},{"cath_id":"2.60.200.10","chopping":"220-411","consensus_level":"high","plddt":95.9424,"start":220,"end":411}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P84022","model_url":"https://alphafold.ebi.ac.uk/files/AF-P84022-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P84022-F1-predicted_aligned_error_v6.png","plddt_mean":83.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SMAD3","jax_strain_url":"https://www.jax.org/strain/search?query=SMAD3"},"sequence":{"accession":"P84022","fasta_url":"https://rest.uniprot.org/uniprotkb/P84022.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P84022/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P84022"}},"corpus_meta":[{"pmid":"9311995","id":"PMC_9311995","title":"TGF-beta 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Dominant-negative SMAD3 inhibited the synergistic transcriptional response.\",\n      \"method\": \"Co-immunoprecipitation in COS cells, phosphorylation assays in Mv1Lu and HSC4 cells, nuclear translocation imaging, transcriptional reporter assay\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, phosphorylation assays, nuclear translocation, reporter assays, replicated across cell lines and multiple labs subsequently\",\n      \"pmids\": [\"9311995\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"SARA (Smad Anchor for Receptor Activation) specifically recognizes monomeric SMAD3, while the transcriptional co-repressor Ski specifically recognizes trimeric SMAD3. Phosphorylation-induced trimerization of SMAD3 simultaneously drives dissociation from SARA (activating TGF-β signal) and sets up Ski-mediated negative feedback. Structural models of SMAD3/SARA/receptor kinase and SMAD3/Ski complexes were generated.\",\n      \"method\": \"Structural modeling, biochemical binding assays distinguishing monomeric vs. trimeric SMAD3, in vitro reconstitution\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — structural modeling with functional biochemical validation, mechanistically clear allosteric mechanism, single lab but multiple orthogonal approaches\",\n      \"pmids\": [\"12154125\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"ERK MAP kinase phosphorylates SMAD3 at Ser207, Ser203, and Thr178 in the linker region upon EGF treatment. Phosphorylation peaks at 15–30 min, is blocked by MEK1 inhibitors, and is recapitulated by recombinant ERK2 in vitro. Mutation of these ERK sites increases SMAD3 transcriptional activity on a Smad target gene, indicating ERK phosphorylation inhibits SMAD3 activity.\",\n      \"method\": \"Phosphopeptide mapping, in vitro kinase assay with recombinant ERK2, site-directed mutagenesis, transcriptional reporter assay\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay with mutagenesis and transcriptional readout, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"16156666\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Non-activated SMAD3 (but not SMAD2) undergoes proteasome-dependent degradation mediated by scaffolding protein Axin and its associated kinase GSK3-β. SMAD3 physically interacts with Axin and GSK3-β only in the absence of TGF-β. GSK3-β phosphorylates SMAD3 at Thr66, triggering SMAD3 ubiquitination and degradation. Thr66 mutants show altered protein stability and transcriptional activity.\",\n      \"method\": \"Co-immunoprecipitation, proteasome inhibitor assays, in vitro phosphorylation, site-directed mutagenesis of Thr66, transcriptional reporter assay\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro phosphorylation with mutagenesis, Co-IP, ubiquitination assay, functional reporter assay; multiple orthogonal methods in single rigorous study\",\n      \"pmids\": [\"18172167\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"SMAD3 DNA binding activity is enhanced by acetylation of Lys19 in the MH1 domain, mediated by coactivators p300 and CBP in a TGF-β-dependent manner. Acetylation of Lys19 induces a conformational change making the MH1 DNA-binding domain accessible. Acetyl-Lys19-specific antibodies confirmed endogenous SMAD3 acetylation in response to TGF-β.\",\n      \"method\": \"In vitro acetylation assay with p300/CBP, site-directed mutagenesis, acetyl-Lys19 antibody, DNA-binding assay, ChIP on target promoters\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro acetylation with mutagenesis, antibody validation, ChIP, DNA-binding assays; multiple orthogonal methods\",\n      \"pmids\": [\"17074756\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Under hypoxic conditions, protein phosphatase 2A (PP2A) specifically dephosphorylates SMAD3 (but not SMAD2). PP2A physically interacts with SMAD3 only under hypoxia, and Smad3-associated PP2A activity is detectable under these conditions. The scaffold subunit PR65 is required for this hypoxic dephosphorylation. Hypoxia attenuates nuclear accumulation of TGF-β-induced SMAD3 and SMAD3-activated gene expression, which is reversed by chemical PP2A inhibition.\",\n      \"method\": \"Co-immunoprecipitation, PP2A activity assay, nuclear translocation assay, gene expression analysis, pharmacological PP2A inhibition\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, phosphatase activity assay, nuclear localization experiments, pharmacological rescue; multiple orthogonal methods single lab\",\n      \"pmids\": [\"19951945\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"SMAD3 specifically represses androgen receptor (AR)-mediated transcription on two natural androgen-responsive promoters. A direct protein-protein interaction between AR and SMAD3 was identified in vitro and in vivo; the transcription activation domain of AR binds the MH2 domain of SMAD3, and the repression of AR is mediated solely through the MH2 domain of SMAD3.\",\n      \"method\": \"Transient transfection reporter assays, GST pulldown (in vitro binding), co-immunoprecipitation (in vivo), domain-mapping mutagenesis\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — GST pulldown + Co-IP + domain mutagenesis + functional reporter assay; multiple orthogonal methods, single lab\",\n      \"pmids\": [\"11280774\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"BRCA2 forms a complex with SMAD3 in vitro and in vivo; both MH1 and MH2 domains of SMAD3 contribute to the interaction. TGF-β1 stimulates interaction of endogenous SMAD3 and BRCA2 in non-transfected cells. BRCA2 co-activates SMAD3-dependent transcriptional activation of PAI-1 and a luciferase reporter, and SMAD3 increases BRCA2 transcriptional activity.\",\n      \"method\": \"GST pulldown, co-immunoprecipitation of endogenous proteins, luciferase reporter assay, domain mapping\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP (including endogenous), GST pulldown, reporter assays; single lab\",\n      \"pmids\": [\"12165866\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"SMAD3 (via its MH1 domain) forms a complex with BRCA1 in vitro and in vivo, and they co-localize in nuclear complexes. TGF-β1/SMAD3 counteracts BRCA1-dependent repair of DNA double-strand breaks, as measured by BRCA1 nuclear foci formation, single-cell gel electrophoresis, and cell survival assays.\",\n      \"method\": \"GST pulldown, co-immunoprecipitation, confocal co-localization, comet assay, colony survival assay, BRCA1 nuclear foci analysis\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP + pulldown + comet assay + functional survival readout; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"15735739\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"FoxL2 directly associates with SMAD3 (but not SMAD2 or SMAD4) through its MH2 domain, and this interaction requires an intact forkhead domain in FoxL2. FoxL2 and SMAD3 are both recruited to the intronic Smad-binding element (SBE1) of the follistatin gene enhancer (confirmed by ChIP) and cooperate to drive activin/SMAD3-mediated follistatin transcription. shRNA knockdown of FoxL2 impairs SBE1-mediated transcription.\",\n      \"method\": \"Co-immunoprecipitation, chromatin immunoprecipitation (ChIP), luciferase reporter assay, shRNA knockdown, domain-mapping mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ChIP, reporter assay, shRNA rescue; multiple orthogonal methods, single lab\",\n      \"pmids\": [\"19106105\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"SMAD3 directly binds to the miR-192 promoter and mediates TGF-β1-induced miR-192 expression specifically (not SMAD2). miR-192 in turn promotes collagen matrix expression downstream of TGF-β/SMAD3 signaling in renal fibrosis.\",\n      \"method\": \"Smad3-selective knockdown/overexpression, promoter binding assay (ChIP), miR-192 mimic/inhibitor functional assays, collagen matrix assays\",\n      \"journal\": \"Journal of the American Society of Nephrology : JASN\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP demonstrating SMAD3 promoter occupancy, Smad2 vs Smad3 specificity tested, functional mimic/inhibitor experiments; single lab\",\n      \"pmids\": [\"20488955\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Smad2 deletion enhances TGF-β/SMAD3 signaling, increasing SMAD3 phosphorylation, nuclear translocation, promoter activity, and binding of SMAD3 to the COL1A2 collagen promoter (by ChIP). Conversely, overexpression of SMAD2 attenuates TGF-β1-induced SMAD3 phosphorylation. This identifies SMAD2 as a counterbalancing regulator of SMAD3 signaling.\",\n      \"method\": \"Conditional Smad2 knockout (renal tubular epithelial cells), ChIP on COL1A2 promoter, SMAD3 phosphorylation Western blot, nuclear translocation assay, promoter reporter assay\",\n      \"journal\": \"Journal of the American Society of Nephrology : JASN\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic deletion (in vivo and in vitro), ChIP, phosphorylation assays, nuclear localization; multiple orthogonal methods, replicated in fibroblasts\",\n      \"pmids\": [\"20595680\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"TRB3 (TRIB3) is a novel SMAD3-interacting protein; the kinase-like domain of TRB3 interacts with the MH2 domain of SMAD3. TRB3 enhances SMAD3 transcriptional activity, promotes nuclear localization of SMAD3 via MH2-domain interaction, and stabilizes phospho-SMAD3 by triggering degradation of Smurf2 (the SMAD ubiquitin regulatory factor 2). TGF-β1 stimulation or SMAD3 overexpression induces TRB3 expression, creating a positive feedback loop.\",\n      \"method\": \"Co-immunoprecipitation, domain-mapping mutagenesis, reporter assay, subcellular localization imaging, siRNA knockdown, Western blot for Smurf2/SMAD2/pSMAD3 levels\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with domain mapping, nuclear localization imaging, Smurf2 degradation functional assay; single lab, multiple methods\",\n      \"pmids\": [\"21896644\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"SMAD3 directly binds to a SMAD-binding element (SBE) in the promoter region of miR-200b/a (confirmed by luciferase reporter with SBE mutagenesis) and functions as a transcriptional activator of miR-200 family members, which in turn suppress ZEB1/ZEB2 and regulate E-cadherin. This regulation occurs independently of TGF-β.\",\n      \"method\": \"Luciferase reporter assay with SBE mutagenesis, SMAD3 overexpression/silencing, miRNA profiling, ChIP (implied by binding element analysis)\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reporter assay with mutagenesis, SMAD3-specific knockdown/overexpression; single lab\",\n      \"pmids\": [\"22020340\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Activated STAT3 directly interacts with SMAD3 in vivo and in vitro, resulting in attenuation of SMAD3-SMAD4 complex formation and suppression of SMAD3 DNA-binding ability. The N-terminal region of the STAT3 DNA-binding domain is responsible for the STAT3-SMAD3 interaction and required for STAT3-mediated inhibition of TGF-β signaling.\",\n      \"method\": \"Co-immunoprecipitation in vivo and in vitro, domain mapping, SMAD3-SMAD4 complex formation assay, SMAD3 DNA-binding assay, STAT3 knockdown with TGF-β response readouts\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP + domain mapping + DNA-binding assay + knockdown functional assays; single lab\",\n      \"pmids\": [\"26616859\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"SMAD3 physically interacts with tendon transcriptional regulators Scleraxis and Mohawk (by Co-IP). Loss of Smad3 in mice reduces collagen 1 and Tenascin-C protein expression, disrupts tendon architecture, and downregulates key tendon marker genes in developing and adult tendon.\",\n      \"method\": \"Co-immunoprecipitation, Smad3-/- mouse model, histology, gene/protein expression analysis\",\n      \"journal\": \"Journal of orthopaedic research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP of endogenous proteins + genetic KO with phenotypic readout; single lab\",\n      \"pmids\": [\"23653374\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"SMAD3 expression is sufficient (via in vivo plasmid transfection) to stimulate atrogin-1 promoter activity, inhibit Akt/mTOR signaling and protein synthesis, and induce muscle fiber atrophy. SMAD3 also inhibits PGC1α promoter activity and increases FoxO-mediated signaling and PAI-1 promoter activity. Mechanistically, SMAD3-induced decrease in miR-29 leads to increased PTEN translation, inhibiting Akt/mTOR.\",\n      \"method\": \"In vivo muscle transfection (transient transgenic), atrogin-1/PGC1α/PAI-1 promoter reporter assays, Akt/mTOR signaling Western blots, miR-29/PTEN assays\",\n      \"journal\": \"Molecular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo gain-of-function with multiple downstream readouts; single lab, single publication\",\n      \"pmids\": [\"24002653\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"WWOX protein physically interacts with SMAD3 via its WW domain 1. WWOX expression reduces SMAD3 occupancy at ANGPTL4 and SERPINE1 promoters (by ChIP), quenches TGF-β-responsive reporter activation, and causes redistribution of SMAD3 from the nuclear to the cytoplasmic compartment.\",\n      \"method\": \"Co-immunoprecipitation, GST pulldown, ChIP, luciferase reporter assay, confocal microscopy for SMAD3 localization, shRNA knockdown\",\n      \"journal\": \"BMC cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP + GST pulldown + ChIP + reporter assay + localization; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"24330518\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Autocrine TGF-β-SMAD3 transcription factor signal (but not SMAD2) is necessary for robust TGF-β expression in dendritic cells activated by Clostridium butyricum, while SMAD2 negatively regulates TGF-β expression. This establishes that SMAD2 and SMAD3 inversely regulate TGF-β autoinduction in dendritic cells.\",\n      \"method\": \"Smad2-deficient and Smad3-deficient dendritic cells, TGF-β reporter assays, cytokine measurement, colitis model\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO of Smad2 vs Smad3 with functional readout, direct comparison; single lab\",\n      \"pmids\": [\"26141582\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PCDH1 (protocadherin-1) binds endogenously to SMAD3 in bronchial epithelial cells (confirmed by Y2H and Co-IP at endogenous levels). PCDH1 overexpression suppresses TGF-β-induced activation of a SMAD3-driven reporter and TGF-β target gene expression, while siRNA knockdown of PCDH1 increases TGF-β-induced SMAD3 transcriptional activity.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation at endogenous protein levels, luciferase reporter assay, siRNA knockdown, TGF-β target gene qPCR\",\n      \"journal\": \"American journal of physiology. Lung cellular and molecular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — endogenous Co-IP + reporter assay + siRNA/overexpression functional assays; single lab\",\n      \"pmids\": [\"26209277\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"OSM (oncostatin M)/STAT3 activation promotes SMAD3 nuclear accumulation and DNA binding in a TGF-β receptor-dependent manner. SMAD3 (but not SMAD2 or SMAD4) is required for OSM/STAT3-mediated epithelial-mesenchymal plasticity and cancer stem cell properties, establishing a STAT3-SMAD3 cooperative signaling axis.\",\n      \"method\": \"SMAD3/SMAD2/SMAD4 ablation (shRNA/CRISPR), nuclear fractionation, SMAD3-DNA binding assay, SMAD3-dependent transcriptional reporter, cancer stem cell/EMT phenotypic assays\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic ablation of specific SMADs with functional phenotypic readouts + nuclear translocation assay; single lab\",\n      \"pmids\": [\"28288136\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"SMAD3 directly suppresses transcription of the NK cell differentiation factor E4BP4/NFIL3 (identified as a direct SMAD3 target gene), thereby inhibiting NK cell development and IFN-γ production. Disruption of SMAD3 in bone marrow expands NK cell population with enhanced tumor-suppressive activity; the SMAD3-E4BP4 axis mediates TGF-β-dependent NK cell immunosuppression.\",\n      \"method\": \"Smad3-/- bone marrow transplant, ex vivo NK cell differentiation assays, E4BP4 promoter reporter assay/ChIP, Smad3 inhibitor (SIS3) treatment, syngeneic tumor models\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO in vivo + ChIP identifying direct target + pharmacological inhibition + multiple functional readouts; multiple orthogonal methods\",\n      \"pmids\": [\"28262747\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Crystal structure of SMAD3 MH2 domain in complex with transcription factor FOXH1 reveals that the MH2 domain has multiple hydrophobic patches that serve as binding interfaces for different cofactors. SMAD3 and SMAD2 use different subsets of these hydrophobic patches to selectively recruit distinct cofactors (e.g., FOXH1 vs. SKI), explaining cofactor selectivity in TGF-β signaling.\",\n      \"method\": \"Crystal structure determination (X-ray crystallography) of SMAD3-FOXH1 and SMAD2-SKI complexes\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structures of SMAD3-cofactor complexes with functional implications for selectivity; single lab but Tier 1 structural method\",\n      \"pmids\": [\"29588413\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"KAT5 acetyltransferase is recruited to SMAD3 by TRIB3 adaptor protein and induces phosphorylation-dependent K333 acetylation of SMAD3, which sustains SMAD3 transcriptional activity and promotes TRIB3 transcription (positive feedback loop). Metformin suppresses SMAD3 phosphorylation and decreases the KAT5/SMAD3 interaction, attenuating K333 acetylation and SMAD3-dependent transcription.\",\n      \"method\": \"Co-immunoprecipitation, in vitro acetylation assay, site-directed mutagenesis (K333), transcriptional reporter assay, metformin treatment in vivo and in vitro\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP + mutagenesis + reporter assay; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"29520103\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Macrophage-specific Smad3 knockout mice exhibit impaired phagocytic activity, defective anti-inflammatory macrophage transition, and adverse cardiac remodeling after myocardial infarction. Phagocytosis directly activates macrophage SMAD3 (independent of TGF-β release). SMAD3-null macrophages show reduced Mfge8 expression (eat-me signal), reduced IL-10 and TGF-β1 production, and attenuated PPAR expression induced by phagocytosis. Mfge8 partially rescues the phagocytic defect.\",\n      \"method\": \"Myeloid-specific Smad3 conditional knockout mice, myocardial infarction model, phagocytosis assays in vitro, cytokine measurement, Mfge8 rescue experiment\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — cell-specific genetic KO in vivo + multiple in vitro mechanistic assays + rescue experiment; multiple orthogonal methods\",\n      \"pmids\": [\"31092129\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"SMAD3 directly binds to the 3'-UTR of TFEB mRNA and inhibits its transcription (confirmed by ChIP at TFEB 3'-UTR). SMAD3-mediated TFEB suppression inhibits lysosome biogenesis, leading to lysosome depletion and autophagy dysregulation in diabetic nephropathy. Pharmacological inhibition or genetic deletion of SMAD3 restores TFEB expression and lysosome biogenesis.\",\n      \"method\": \"ChIP demonstrating SMAD3 binding at TFEB 3'-UTR, SMAD3 genetic deletion/inhibition (SIS3), TFEB silencing rescue experiment, lysosome biogenesis assays (LAMP1, autophagic flux)\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP + genetic KO + siRNA rescue; single lab, multiple methods\",\n      \"pmids\": [\"33043774\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"SMAD3 binding to fibroblast differentiation gene promoters in macrophage-lineage cells (detected by ChIP-seq) drives macrophage-to-myofibroblast transition (MMT), generating cancer-associated fibroblasts. Macrophage-specific deletion or pharmacological inhibition of SMAD3 blocks MMT and suppresses CAF formation and tumor progression in vivo.\",\n      \"method\": \"ChIP-seq (SMAD3 binding), macrophage-specific Smad3 conditional KO, adoptive transfer of BMDM-derived MMTs, single-cell RNA-seq, pharmacological inhibition (SIS3), Lewis lung carcinoma model\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ChIP-seq + cell-specific genetic KO + pharmacological inhibition + in vivo functional assays; multiple orthogonal methods\",\n      \"pmids\": [\"34791825\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"USP7 deubiquitinase removes mono-ubiquitin from SMAD3 (deubiquitination of SMAD3), which is required for SMAD3 DNA-binding activity. Mono-ubiquitination of SMAD3 negatively regulates its DNA-binding function; USP7-mediated de-monoubiquitination of SMAD3 facilitates SMAD3-SMAD4 dimer binding at the SMAD3 locus super-enhancer, enabling SMAD3 autoregulation.\",\n      \"method\": \"USP7 CRISPR/Cas9 KO, ChIP-seq and RNA-seq (genome-wide), cell-free and cell-based ubiquitination/deubiquitination assays, SMAD3 autoregulation reporter assay\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP-seq + biochemical deubiquitination assay + CRISPR KO functional readouts; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"34580281\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"SO2-derived peroxymonosulfite promotes sulfenylation (cysteine oxidation) of SMAD3 at cysteine-64, inhibiting its DNA-binding activity. Mutation of Cys64 attenuates the protective effects of SO2 on angiotensin II-induced vascular remodeling and hypertension, establishing this redox modification as functionally relevant.\",\n      \"method\": \"Site-centric chemoproteomics (sulfenylation quantification), site-directed mutagenesis (Cys64), vascular smooth muscle cell assays, angiotensin II hypertension mouse model\",\n      \"journal\": \"Redox biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — chemoproteomic identification of modification site + mutagenesis + in vivo functional rescue; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"33647858\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"EZH2 methylates SMAD3 at K53 and K333; this methylation facilitates SMAD3 interaction with its membrane-localization molecule SARA, which in turn sustains SMAD3 phosphorylation by the TGF-β receptor. EZH2-mediated SMAD3 K53/K333 methylation is required for full SMAD3 activation upon TGF-β1 stimulation and promotes tumor metastasis.\",\n      \"method\": \"In vitro methylation assay with recombinant EZH2, site-directed mutagenesis (K53, K333), Co-IP (SMAD3-SARA interaction), TGF-β receptor phosphorylation assay, breast cancer metastasis xenograft model, TAT peptide therapeutic inhibition\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro methylation reconstitution + mutagenesis + Co-IP of SARA interaction + functional rescue in vivo; multiple orthogonal methods in single rigorous study\",\n      \"pmids\": [\"35085106\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TGF-β/activin-activated SMAD3 (but not SMAD1) promotes SOX2 expression and anchorage-independent survival in ovarian cancer via SMAD3-dependent histone H3K4me3 recruitment at the SOX2 promoter. Conversely, BMP/SMAD1 represses SOX2 through H3K27me3 and DNA methylation.\",\n      \"method\": \"SMAD3 knockdown/knockout, ChIP for H3K4me3 at SOX2 promoter, gene expression profiling, anchorage-independent survival assays, intraperitoneal tumor burden assays\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP for specific histone marks + genetic manipulation + in vivo functional assays; single lab\",\n      \"pmids\": [\"35905726\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"SIRT2 deacetylase directly interacts with and deacetylates SMAD3 at lysine 341 and K378, reducing SMAD3 activation. SMAD3 deacetylation by SIRT2 occurs only in the presence of TGF-β and reduces SMAD3 phosphorylation, nuclear localization, and downstream fibrotic gene expression.\",\n      \"method\": \"Co-immunoprecipitation, in vitro deacetylation assay, site-directed mutagenesis (K341, K378), SIRT2 conditional KO mice, nuclear localization assays, fibrotic gene expression readouts\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP + in vitro deacetylation + mutagenesis + genetic KO functional assays; single lab\",\n      \"pmids\": [\"37777567\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"SMAD3 binds to intron 3 of the AR (androgen receptor) gene to promote AR expression (identified by ChIP-seq; binding sites validated by CRISPRi). Approximately 50% of AR and SMAD3 ChIP-seq peaks overlap, indicating SMAD3 also co-occupies AR target gene loci. SMAD3 knockdown decreases AR levels and AR target gene expression, an effect partially rescued by AR re-expression.\",\n      \"method\": \"SMAD3 knockdown (siRNA), ChIP-seq (SMAD3 and AR binding), RNA-seq, CRISPRi targeting SMAD3-binding sites in AR intron 3, AR rescue experiments, SMAD3 PROTAC inhibitor\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ChIP-seq + CRISPRi functional validation + RNA-seq + rescue experiments; multiple orthogonal genome-wide and functional methods\",\n      \"pmids\": [\"36727462\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ATOH8 binds SMAD3 to form a transcriptional complex that directly represses cell cycle-promoting genes and induces oncogene-induced senescence (OIS) in lung epithelial cells downstream of Ras overactivation and TGF-β1/SMAD3 signaling. SMAD3 (not SMAD2 or SMAD4) is the determinant mediator of this senescence response. Depletion of ATOH8 accelerates Ras-driven lung tumorigenesis and confers sensitivity to SMAD3 inhibitor.\",\n      \"method\": \"Co-immunoprecipitation (ATOH8-SMAD3 complex), SMAD3/SMAD2/SMAD4 knockdown specificity assays, transcriptional profiling of repressed cell cycle genes, ATOH8 deletion mouse model, Smad3 inhibitor treatment\",\n      \"journal\": \"PNAS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP + SMAD-specific knockdown + in vivo KO tumor model + pharmacological rescue; single lab, multiple methods\",\n      \"pmids\": [\"36626550\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Cell intercalation downstream of TGF-β/SMAD3 signaling is required for secondary neural tube formation in vivo. SMAD3 acts with YAP to resolve a centrally positioned lumen through cell intercalation during tail bud development, demonstrated by SMAD3 loss-of-function experiments and live in vivo imaging in chicken embryo.\",\n      \"method\": \"In vivo SMAD3 loss-of-function (chick embryo electroporation), live imaging of cell intercalation, YAP inhibition assays, lumen formation readout\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo loss-of-function with live imaging readout; single lab, single publication\",\n      \"pmids\": [\"33878300\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Linker-region phosphorylation of SMAD3 (at four sites mutated in the EPSM mutant) negatively regulates SMAD3 transcriptional activity and TGF-β1/SMAD3-induced epithelial-mesenchymal transition in renal epithelial cells. C-terminal SSXS phosphorylation is essential for mediating TGF-β response, while linker phosphorylation acts as a brake.\",\n      \"method\": \"Site-directed mutagenesis (EPSM and 3S-A SMAD3 mutants), TGF-β1 induction of EMT in Smad3-deficient primary renal cells reconstituted with mutants, Western blot and RT-PCR for EMT markers\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis of phosphorylation sites with functional EMT readout; single lab, clean mechanistic result\",\n      \"pmids\": [\"23022526\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"p-Akt physically interacts with SMAD3 in wild-type mouse muscles and C2C12 myoblasts (by co-immunoprecipitation). IGF-I increases p-Akt/SMAD3 interaction (retaining SMAD3 in cytoplasm), while TGF-β1 decreases it, allowing SMAD3 nuclear translocation and fibronectin expression. This p-Akt/SMAD3 interaction constitutes a molecular switch between myogenesis and fibrogenesis.\",\n      \"method\": \"Co-immunoprecipitation of p-Akt and SMAD3, IGF-I/TGF-β1 treatment, SMAD3 nuclear translocation assay, fibronectin expression, IGF-IR heterozygous KO mouse model\",\n      \"journal\": \"American journal of physiology. Endocrinology and metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP demonstrating p-Akt/SMAD3 interaction + nuclear translocation assay + in vivo KO model; single lab\",\n      \"pmids\": [\"23736539\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SMAD3 is a TGF-β/activin pathway transcription factor that is recruited to the activated TβR-I/II receptor complex via SARA in its monomeric form, phosphorylated at its C-terminal SSXS motif by TβR-I, which drives trimerization, dissociation from SARA, and nuclear translocation with SMAD4; its activity is tightly regulated by phosphorylation (GSK3-β at Thr66 triggers degradation; ERK at Ser203/207/Thr178 inhibits activity; linker phosphorylation acts as a brake; PP2A specifically dephosphorylates it under hypoxia), by acetylation (p300/CBP at Lys19 enhances DNA binding; KAT5 at K333 sustains activity), by methylation (EZH2 at K53/K333 facilitates SARA interaction and receptor phosphorylation), by mono-ubiquitination (inhibits DNA binding, reversed by USP7), and by cysteine sulfenylation (Cys64, inhibits DNA binding); in the nucleus SMAD3 selectively interacts with a wide range of cofactors (FOXH1, SKI, FoxL2, Scleraxis, Mohawk, EGR1, Pitx2, ATOH8, STAT3, AR, BRCA1/2, WWOX, PCDH1, TRB3) through distinct hydrophobic patches on its MH2 domain to drive or repress transcription of target genes including collagen, PAI-1, miR-192, miR-200, E4BP4/NFIL3, TFEB, and AR, thereby orchestrating fibrosis, immune regulation, NK cell development, muscle atrophy, and cancer progression.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SMAD3 is the central signal-transducing transcription factor of the TGF-\\u03b2/activin pathway, coupling receptor activation at the membrane to gene-regulatory programs that govern fibrosis, immune regulation, cancer progression, and tissue development [#0, #21, #26]. Upon TGF-\\u03b2 stimulation, SMAD3 is recruited to and phosphorylated by the activated T\\u03b2R-I/II receptor complex, forms heteromeric complexes with SMAD4 (and SMAD2), translocates to the nucleus, and synergistically activates target promoters such as PAI-1 [#0]; SARA recognizes monomeric SMAD3 while phosphorylation-driven trimerization simultaneously releases SARA and exposes SMAD3 to Ski-mediated negative feedback [#1]. Activation is gated by a dense layer of post-translational modifications: C-terminal SSXS phosphorylation is essential while linker-region phosphorylation acts as a brake [#35], ERK phosphorylation at Ser203/Ser207/Thr178 and GSK3-\\u03b2 phosphorylation at Thr66 (driving Axin-dependent proteasomal degradation) restrain activity [#2, #3], hypoxic PP2A dephosphorylates SMAD3 specifically [#5], EZH2 methylation at K53/K333 promotes the SARA interaction and receptor-mediated phosphorylation [#29], p300/CBP acetylation at Lys19 and KAT5 acetylation at K333 enhance DNA binding and sustain activity (opposed by SIRT2 deacetylation) [#4, #23, #31], and mono-ubiquitination and Cys64 sulfenylation each inhibit DNA binding, the former reversed by USP7 to enable SMAD3 autoregulation [#27, #28]. In the nucleus, distinct hydrophobic patches on the SMAD3 MH2 domain confer cofactor selectivity \\u2014 a crystal structure of the MH2\\u2013FOXH1 complex established how SMAD3 versus SMAD2 recruit different partners [#22] \\u2014 allowing SMAD3 to engage a wide range of context-specific cofactors including FoxL2, Scleraxis/Mohawk, ATOH8, STAT3, the androgen receptor, BRCA1/BRCA2, and WWOX to activate or repress transcription [#9, #15, #33, #6, #7, #8, #17]. Through these interactions SMAD3 binds defined promoter and enhancer elements to control collagen, PAI-1, miR-192, miR-200, the NK-cell factor E4BP4/NFIL3, TFEB, and AR, thereby driving renal and tendon fibrosis, macrophage-to-myofibroblast transition, muscle atrophy, NK-cell immunosuppression, and EMT/stemness programs [#10, #13, #21, #25, #26, #16, #20]. SMAD3 function is consistently distinguished from SMAD2, which acts as a counterbalancing or opposing regulator across renal, immune, and developmental contexts [#11, #18].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"Established SMAD3 as a direct receptor-activated effector of TGF-\\u03b2, answering how an extracellular cytokine signal reaches the nucleus to control transcription.\",\n      \"evidence\": \"Co-IP, phosphorylation assays, nuclear translocation imaging, and PAI-1 reporter assays across COS, Mv1Lu, and HSC4 cells\",\n      \"pmids\": [\"9311995\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve the structural basis of receptor recognition\", \"Stoichiometry of the SMAD2/3/4 complex left undefined\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Showed SMAD3 functions not only as an activator but as a direct transcriptional repressor, here of androgen-receptor-mediated transcription, expanding its regulatory repertoire.\",\n      \"evidence\": \"GST pulldown, Co-IP, and reporter assays mapping the AR activation domain to the SMAD3 MH2 domain\",\n      \"pmids\": [\"11280774\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of repression at native chromatin not defined\", \"Relationship to TGF-\\u03b2 stimulation unclear\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Defined the allosteric logic linking phosphorylation to signaling state: monomeric SMAD3 binds SARA, trimeric SMAD3 binds Ski, so trimerization both activates and sets up negative feedback.\",\n      \"evidence\": \"Structural modeling with biochemical binding assays distinguishing monomeric vs. trimeric SMAD3\",\n      \"pmids\": [\"12154125\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Based on modeling rather than experimental structures of full complexes\", \"Kinetics of the monomer-to-trimer transition not measured\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Linked SMAD3 to DNA-damage-response machinery by identifying BRCA2 as a bidirectional transcriptional partner.\",\n      \"evidence\": \"GST pulldown, endogenous Co-IP after TGF-\\u03b21, and luciferase reporter assays with domain mapping\",\n      \"pmids\": [\"12165866\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Functional consequence at endogenous target genes not established\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Demonstrated that SMAD3 integrates RTK input, with ERK phosphorylating the linker to inhibit SMAD3 transcriptional output \\u2014 a crosstalk node between growth-factor and TGF-\\u03b2 signaling.\",\n      \"evidence\": \"Phosphopeptide mapping, in vitro ERK2 kinase assay, mutagenesis of Ser203/Ser207/Thr178, reporter assay\",\n      \"pmids\": [\"16156666\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance of each site not dissected\", \"Mechanism by which linker phosphorylation reduces activity unresolved\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Connected SMAD3 to DNA double-strand-break repair, showing TGF-\\u03b2/SMAD3 antagonizes BRCA1-dependent repair.\",\n      \"evidence\": \"GST pulldown, Co-IP, confocal co-localization, comet and colony-survival assays, BRCA1 foci analysis\",\n      \"pmids\": [\"15735739\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Direct chromatin mechanism of repair interference not defined\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identified SMAD3-specific degradation control, with GSK3-\\u03b2 phosphorylating Thr66 in unstimulated cells to trigger Axin-scaffolded ubiquitin-proteasome turnover.\",\n      \"evidence\": \"Co-IP, proteasome inhibitor assays, in vitro phosphorylation, Thr66 mutagenesis, reporter assay\",\n      \"pmids\": [\"18172167\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"E3 ligase responsible not identified\", \"Quantitative contribution to basal SMAD3 pool unclear\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Established acetylation as a positive activating mark, with p300/CBP acetylating Lys19 to expose the MH1 DNA-binding domain.\",\n      \"evidence\": \"In vitro acetylation assay, Lys19 mutagenesis, acetyl-Lys19 antibody, DNA-binding and ChIP assays\",\n      \"pmids\": [\"17074756\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Deacetylase counteracting Lys19 not identified here\", \"Interplay with phosphorylation timing not resolved\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Revealed cofactor-directed promoter selectivity, with FoxL2 recruiting SMAD3 specifically (not SMAD2/4) to the follistatin SBE1 enhancer.\",\n      \"evidence\": \"Co-IP, ChIP, luciferase reporter, shRNA knockdown, domain mapping requiring the forkhead domain\",\n      \"pmids\": [\"19106105\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the MH2-forkhead interface not defined\", \"Generality to other forkhead partners untested here\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Showed SMAD3 signaling is tuned by environmental oxygen, with hypoxia-recruited PP2A specifically dephosphorylating SMAD3 to dampen nuclear accumulation.\",\n      \"evidence\": \"Co-IP, PP2A activity assay, nuclear translocation and gene-expression analysis, pharmacological PP2A inhibition; PR65 scaffold requirement\",\n      \"pmids\": [\"19951945\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How hypoxia targets PP2A to SMAD3 specifically not defined\", \"Phospho-sites dephosphorylated not mapped\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Defined SMAD2 as a counterbalancing regulator of SMAD3 and identified miR-192 as a direct SMAD3 target driving fibrotic collagen output.\",\n      \"evidence\": \"Conditional Smad2 knockout, ChIP on COL1A2 and miR-192 promoters, phosphorylation and reporter assays, miRNA functional assays\",\n      \"pmids\": [\"20595680\", \"20488955\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which SMAD2 limits SMAD3 phosphorylation not fully resolved\", \"Direct vs. indirect promoter occupancy at some loci inferred\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Uncovered positive-feedback partners (TRB3) that stabilize phospho-SMAD3 and identified miR-200 as a TGF-\\u03b2-independent SMAD3 target controlling EMT regulators.\",\n      \"evidence\": \"Co-IP and domain mapping, Smurf2 degradation assay, localization imaging; SBE-mutagenesis luciferase reporter and SMAD3 manipulation for miR-200\",\n      \"pmids\": [\"21896644\", \"22020340\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single labs\", \"ChIP occupancy at miR-200 promoter inferred rather than directly shown\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Distinguished the functional roles of C-terminal versus linker phosphorylation, showing the SSXS tail is essential for activation while linker phosphorylation acts as a brake on EMT.\",\n      \"evidence\": \"EPSM and 3S-A SMAD3 mutants reconstituted into Smad3-deficient renal cells with EMT marker readouts\",\n      \"pmids\": [\"23022526\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Kinases acting at each linker site in this context not assigned\", \"Single lab\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Extended SMAD3's reach into tendon, muscle, and a cytoplasmic myogenesis/fibrogenesis switch, defining tissue-specific cofactors and signaling crosstalk.\",\n      \"evidence\": \"Co-IP with Scleraxis/Mohawk and Smad3 KO histology; in vivo muscle transfection with atrogin-1/PGC1\\u03b1 readouts and miR-29/PTEN axis; p-Akt/SMAD3 Co-IP with IGF-I/TGF-\\u03b21 switching\",\n      \"pmids\": [\"23653374\", \"24002653\", \"23736539\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single labs per tissue\", \"Direct vs. indirect transcriptional targets in atrophy not all mapped\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identified WWOX as a negative regulator that sequesters SMAD3 in the cytoplasm and reduces its promoter occupancy.\",\n      \"evidence\": \"Co-IP, GST pulldown, ChIP at ANGPTL4/SERPINE1, reporter assay, confocal localization, shRNA\",\n      \"pmids\": [\"24330518\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Whether sequestration is direct or via altered phosphorylation unclear\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Established opposing SMAD2/SMAD3 control of immune programs, with SMAD3 required for TGF-\\u03b2 autoinduction in dendritic cells and engaging a STAT3 interaction that inhibits SMAD3 DNA binding.\",\n      \"evidence\": \"Smad2/Smad3-deficient dendritic cells with colitis model; reciprocal Co-IP, SMAD3-SMAD4 complex and DNA-binding assays with STAT3 domain mapping\",\n      \"pmids\": [\"26141582\", \"26616859\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single labs\", \"Context-dependence of STAT3 inhibition vs. cooperation not reconciled here\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identified PCDH1 as an endogenous brake on SMAD3 transcriptional activity in airway epithelium.\",\n      \"evidence\": \"Yeast two-hybrid, endogenous Co-IP, reporter and siRNA/overexpression functional assays with target qPCR\",\n      \"pmids\": [\"26209277\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Subcellular mechanism of inhibition not defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defined SMAD3-specific roles in immune and cancer-stemness programs: direct repression of E4BP4/NFIL3 to suppress NK-cell development, and a cooperative STAT3-SMAD3 axis driving EMP/stemness.\",\n      \"evidence\": \"Smad3 KO bone marrow with NK differentiation, E4BP4 ChIP/reporter, SIS3 inhibitor, tumor models; SMAD-specific ablation with nuclear fractionation and DNA-binding/phenotypic assays for OSM/STAT3\",\n      \"pmids\": [\"28262747\", \"28288136\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How STAT3 here promotes vs. elsewhere inhibits SMAD3 DNA binding not reconciled\", \"Direct SMAD3 targets in stemness program not fully enumerated\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Provided the structural explanation for cofactor selectivity, showing the SMAD3 MH2 domain uses distinct hydrophobic patches to recruit different partners (FOXH1 vs. SKI).\",\n      \"evidence\": \"X-ray crystal structures of SMAD3-FOXH1 and SMAD2-SKI complexes\",\n      \"pmids\": [\"29588413\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structures of additional cofactor complexes not solved\", \"Affinity hierarchy among competing cofactors not measured\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Added acetylation-based amplification, with TRIB3-recruited KAT5 acetylating K333 to sustain SMAD3 activity in a feedback loop druggable by metformin.\",\n      \"evidence\": \"Co-IP, in vitro acetylation, K333 mutagenesis, reporter assay, metformin treatment in vitro and in vivo\",\n      \"pmids\": [\"29520103\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Interplay between K333 acetylation and K333 methylation not resolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showed phagocytosis directly activates macrophage SMAD3 independent of TGF-\\u03b2 release, driving anti-inflammatory transition and adaptive cardiac remodeling.\",\n      \"evidence\": \"Myeloid-specific Smad3 conditional KO, myocardial infarction model, phagocytosis and cytokine assays, Mfge8 rescue\",\n      \"pmids\": [\"31092129\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Receptor coupling phagocytosis to SMAD3 phosphorylation not identified\", \"Direct vs. indirect control of Mfge8 not shown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Linked SMAD3 to autophagy and lysosomal biogenesis by direct repression of TFEB, explaining lysosome depletion in diabetic nephropathy.\",\n      \"evidence\": \"ChIP at the TFEB 3'-UTR, SMAD3 deletion/SIS3 inhibition, TFEB silencing rescue, lysosome/autophagy flux assays\",\n      \"pmids\": [\"33043774\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Mechanism of 3'-UTR-targeted transcriptional repression atypical and not fully explained\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Established multiple new layers of SMAD3 regulation and output: USP7-mediated de-monoubiquitination enabling DNA binding and autoregulation, Cys64 sulfenylation as a redox off-switch, macrophage-to-myofibroblast transition generating CAFs, and a SMAD3/YAP role in neural tube morphogenesis.\",\n      \"evidence\": \"USP7 CRISPR KO with ChIP-seq/RNA-seq and ubiquitination assays; chemoproteomics with Cys64 mutagenesis in hypertension model; SMAD3 ChIP-seq with macrophage-specific KO and SIS3 in lung carcinoma; chick-embryo SMAD3 loss-of-function with live imaging\",\n      \"pmids\": [\"34580281\", \"33647858\", \"34791825\", \"33878300\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"E3 ligase depositing the mono-ubiquitin not identified\", \"Enzymatic source of Cys64 sulfenylation in vivo not defined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined methylation-driven activation and its acetyl/deacetyl counterbalance, plus SMAD3-specific chromatin output: EZH2 K53/K333 methylation promotes SARA binding and receptor phosphorylation, SIRT2 deacetylates K341/K378 to dampen activity, and SMAD3 drives SOX2 via H3K4me3.\",\n      \"evidence\": \"In vitro methylation/deacetylation reconstitution, site mutagenesis, SARA Co-IP, conditional KO mice, ChIP for histone marks, breast and ovarian cancer models\",\n      \"pmids\": [\"35085106\", \"37777567\", \"35905726\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Combinatorial logic among competing modifications at shared residues (e.g., K333) not resolved\", \"Some findings single-lab\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Established genome-wide SMAD3 control of the androgen receptor and a SMAD3-ATOH8 senescence program, expanding SMAD3's transcriptional reach in cancer.\",\n      \"evidence\": \"SMAD3 and AR ChIP-seq with CRISPRi validation, RNA-seq, AR rescue, PROTAC inhibitor; ATOH8-SMAD3 Co-IP, SMAD-specific knockdown, ATOH8 deletion tumor model, SMAD3 inhibitor\",\n      \"pmids\": [\"36727462\", \"36626550\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How SMAD3 selects activating vs. repressive programs genome-wide not fully defined\", \"Cofactor partition between AR co-occupancy and senescence loci unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the dozens of competing post-translational modifications (often on shared residues such as K333) and the many context-specific cofactors are integrated to determine whether SMAD3 activates or represses a given locus remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model reconciling competing modifications at shared lysines\", \"Quantitative cofactor competition at the MH2 hydrophobic patches not mapped genome-wide\", \"Determinants of activator vs. repressor mode at individual targets undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 9, 10, 13, 21, 25, 26, 32, 33]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [4, 14, 27, 28]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 5, 17, 36]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [17, 36]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [0, 8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 22]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 9, 21, 25, 32]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [18, 21, 24]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [20, 26, 30, 33]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [34, 15]}\n    ],\n    \"complexes\": [\n      \"SMAD3-SMAD4 complex\",\n      \"SMAD3-SMAD2-SMAD4 receptor-activated complex\"\n    ],\n    \"partners\": [\n      \"SMAD4\",\n      \"SMAD2\",\n      \"SARA\",\n      \"FOXH1\",\n      \"STAT3\",\n      \"TRIB3\",\n      \"AR\",\n      \"BRCA1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}