{"gene":"TNNI3K","run_date":"2026-06-10T10:51:55","timeline":{"discoveries":[{"year":2007,"finding":"TNNI3K exhibits dual-specificity kinase activity (Tyr and Ser/Thr), forms dimers or oligomers required for activation, the C-terminal Ser-rich domain negatively regulates kinase activity, and the N-terminal ANK domain is necessary for autophosphorylation.","method":"In vitro kinase assay, domain deletion/mutagenesis analysis","journal":"General physiology and biophysics","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro kinase assay with domain mutagenesis, single lab, single study","pmids":["17660584"],"is_preprint":false},{"year":2007,"finding":"Antioxidant protein 1 (AOP-1) interacts with the ANK motif of TNNI3K (identified by yeast two-hybrid, confirmed by in vitro binding assay and co-expression), co-localizes with TNNI3K, and inhibits TNNI3K kinase activity in vitro.","method":"Yeast two-hybrid screen, in vitro binding assay, co-immunoprecipitation, confocal immunofluorescence, in vitro kinase assay","journal":"Biochemistry. Biokhimiia","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal binding confirmed by multiple orthogonal methods (Y2H, in vitro binding, co-IP, kinase assay), single lab","pmids":["18205602"],"is_preprint":false},{"year":2007,"finding":"MEF2C binds to the TNNI3K/CARK promoter at a conserved MEF2 site that is the most critical cis-acting element for cardiac-specific transcription; MEF2C antisense reduces CARK transcript levels.","method":"Promoter truncation/mutational analysis, EMSA (supershift), co-transfection assays","journal":"Journal of cellular and molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — EMSA supershift plus functional co-transfection and mutational analysis, single lab","pmids":["18021318"],"is_preprint":false},{"year":2008,"finding":"TNNI3K overexpression promotes differentiation of P19CL6 cells into cardiomyocytes, suppresses p38/JNK-mediated apoptosis (reduced annexin-V+ cells, Bax, and p38/JNK phosphorylation), and improves cardiac function in a mouse myocardial infarction model.","method":"Cell transfection/overexpression, flow cytometry (apoptosis), Western blot (p38/JNK phosphorylation), intramyocardial cell injection in MI mouse model","journal":"American journal of physiology. Heart and circulatory physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods in vitro and in vivo, single lab","pmids":["18552163"],"is_preprint":false},{"year":2009,"finding":"TNNI3K expression accelerates cardiac dysfunction in the Calsequestrin transgenic mouse model of cardiomyopathy and in a pressure-overload model; high TNNI3K transcript levels correlate with increased disease susceptibility, while a splice-activating intronic SNP causes nonsense-mediated decay and loss of detectable protein in resistant strains.","method":"Transgenic mouse models (TNNI3K/Csq double transgenic, pressure overload), genetic mapping, RT-PCR, Western blot","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple transgenic and congenic mouse models with defined phenotypic readouts, replicated across two cardiac disease models","pmids":["19763165"],"is_preprint":false},{"year":2012,"finding":"TNNI3K is a dual-function kinase (Tyr and Ser/Thr activity) in vivo; its kinase activity (not merely overexpression) drives cardiac remodeling including sarcomere length reduction and titin isoform changes, as shown by kinase-dead transgenic mice lacking these effects; TNNI3K protein localizes to the sarcomere Z disc.","method":"Transgenic mice (wild-type vs. kinase-dead TNNI3K), in vitro kinase assay, proteomics, immunofluorescence/immunostaining, pressure-overload model","journal":"Journal of molecular and cellular cardiology","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — kinase-dead vs. wild-type transgenic comparison with defined molecular phenotypes, in vitro kinase assay, subcellular localization; single lab but multiple orthogonal methods","pmids":["23085512"],"is_preprint":false},{"year":2012,"finding":"Tnni3k mRNA level positively correlates with PR interval duration in mice; overexpression of hTNNI3K in DBA/2J mice prolongs the PR interval, identifying Tnni3k as a modulator of atrio-ventricular conduction.","method":"Expression QTL mapping, ECG measurements in congenic and transgenic mouse lines, correlation analysis of mRNA and PR interval","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple independent mouse strains/models (transgenic overexpression + congenic lines) with direct ECG phenotyping, replicated across genetic backgrounds","pmids":["23236294"],"is_preprint":false},{"year":2013,"finding":"TNNI3K phosphorylates cardiac troponin I (cTnI) at Ser43 and Thr143 in vitro and in adult rat cardiomyocytes (not at Ser23/24 or Ser44); TNNI3K overexpression increases and knockdown decreases cTnI phosphorylation at these sites; increased TNNI3K/cTnI interaction enhances cardiomyocyte contraction.","method":"Co-immunoprecipitation, in vitro kinase assay, adult rat cardiomyocyte overexpression/knockdown, cardiomyocyte contraction measurements","journal":"Brazilian journal of medical and biological research","confidence":"Medium","confidence_rationale":"Tier 1–2 / Weak — in vitro kinase assay with site identification plus cellular KD/OE with functional readout, single lab","pmids":["23369981"],"is_preprint":false},{"year":2013,"finding":"TNNI3K physically interacts with cTnI (confirmed by co-immunoprecipitation and yeast two-hybrid), induces cTnI phosphorylation at Ser22/Ser23 in vivo and in vitro, and promotes concentric cardiac hypertrophy with enhanced cardiac function in transgenic mice; phosphoamino acid analysis confirmed TNNI3K is a protein-tyrosine kinase.","method":"Yeast two-hybrid, co-immunoprecipitation, in vivo and in vitro phosphorylation assays, transgenic mouse echocardiography","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal binding (Y2H + Co-IP) plus in vivo phosphorylation with transgenic model, single lab","pmids":["23472207"],"is_preprint":false},{"year":2013,"finding":"TNNI3K promotes ischemia/reperfusion injury through increased mitochondrial superoxide production, impaired mitochondrial function, and p38 MAPK activation; pharmacologic TNNI3K inhibition reduces mitochondrial superoxide, p38 activation, and infarct size when delivered at reperfusion.","method":"Small-molecule inhibitor treatment in mouse I/R model, mitochondrial superoxide measurement, p38 MAPK phosphorylation assay, infarct size measurement, echocardiography","journal":"Science translational medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal mechanistic readouts (superoxide, mitochondrial function, p38, infarct size) in an in vivo model with pharmacologic intervention replicated with multiple inhibitor compounds","pmids":["24132636"],"is_preprint":false},{"year":2014,"finding":"A missense mutation G526D in the TNNI3K kinase domain causes abnormal peptide aggregation in vitro; in silico docking predicts altered but energetically favorable dimerization; ventricular tissue from a carrier shows reduced TNNI3K protein staining with nuclear/sarcoplasmic inclusions, implicating dominant-negative loss-of-function.","method":"In vitro aggregation assay, in silico docking, immunohistochemistry of human ventricular tissue","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — in vitro aggregation assay and human tissue IHC, supported by computational modeling; single study, limited experimental validation","pmids":["24925317"],"is_preprint":false},{"year":2015,"finding":"X-ray crystal structure of a purine inhibitor (compound 1) bound to TNNI3K confirmed Type I binding mode to the kinase domain, enabling rational structure-guided inhibitor design and delineation of structure-activity relationships.","method":"X-ray crystallography of TNNI3K-inhibitor complex","journal":"Journal of medicinal chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure determination with functional SAR validation, single lab but rigorous structural method","pmids":["26355916"],"is_preprint":false},{"year":2018,"finding":"The TNNI3K p.Glu768Lys variant displays enhanced kinase autophosphorylation activity compared to wild-type TNNI3K, and co-segregates with disease in 23 affected individuals across 3 independent families presenting with supraventricular tachycardia, conduction disturbance, and DCM.","method":"Autophosphorylation kinase assay, next-generation sequencing, co-segregation analysis","journal":"Heart rhythm","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — autophosphorylation assay plus multi-family co-segregation; functionally replicated across 3 families, single lab","pmids":["30010057"],"is_preprint":false},{"year":2019,"finding":"Tnni3k function requires its kinase activity (shown by kinase-dead allele in mice); Tnni3k regulates the frequency of mononuclear diploid cardiomyocytes and converges with oxidative stress in this regulation; common human TNNI3K kinase domain variants substantially compromise kinase activity in vitro.","method":"In vitro kinase assay of human variants, kinase-dead knock-in mouse model, cardiomyocyte ploidy analysis","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro kinase assay of multiple human variants plus genetic knock-in mouse with defined cellular phenotype, multiple orthogonal methods in single rigorous study","pmids":["31589606"],"is_preprint":false},{"year":2021,"finding":"Loss of TNNI3K kinase activity (null allele, kinase-dead K489R, or hypomorphic I686T variant) causes concentric ventricular remodeling, impaired cardiomyocyte contractility, defective calcium dynamics, and reduced PKA signaling in response to isoproterenol in cultured cardiomyocytes, demonstrating a beneficial role for TNNI3K in maintaining normal cardiac geometry and contractile reserve.","method":"Tnni3k knockout and knock-in mouse models, echocardiography, cardiomyocyte contractility and calcium imaging, PKA signaling assay in culture","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Moderate — three independent genetic alleles producing same phenotype, multiple cellular readouts including contractility, calcium, and PKA signaling; single lab but multiple orthogonal approaches","pmids":["33084860"],"is_preprint":false},{"year":2021,"finding":"X-ray crystal structures of TNNI3K with diarylurea inhibitors enabled structure-based design of selective TNNI3K inhibitors over VEGFR2, p38α, and B-Raf; a tool compound (GSK329) showed cardioprotective effects in a mouse I/R model.","method":"X-ray crystallography of TNNI3K-inhibitor complexes, structure-based medicinal chemistry, in vivo I/R mouse model","journal":"Journal of medicinal chemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — crystal structure and in vivo model, but primarily a medicinal chemistry study; single lab","pmids":["34699203"],"is_preprint":false},{"year":2023,"finding":"Novel TNNI3K variants p.Ile512Thr and p.His592Tyr show increased autophosphorylation activity and co-segregate with DCM, conduction disease, and supraventricular tachycardia; a likely benign variant (p.Arg556_Asn590del) shows depleted autophosphorylation, suggesting enhanced autophosphorylation drives pathogenicity.","method":"TNNI3K autophosphorylation assay, next-generation sequencing, co-segregation analysis, UK Biobank burden testing","journal":"Circulation. Genomic and precision medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — autophosphorylation assay plus co-segregation in independent families and population-level burden testing; single lab","pmids":["37199186"],"is_preprint":false},{"year":2023,"finding":"Tnni3k influences both early S-phase entry and the completion of cell division (cytokinesis) in cardiomyocytes, demonstrating roles at distinct stages of the cell cycle.","method":"Retrospective single-cell analysis of ventricular cardiomyocyte suspensions to identify post-division cells, genetic loss-of-function (Tnni3k knockout)","journal":"Journal of molecular and cellular cardiology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — defined cellular phenotype with loss-of-function model, single lab, single method","pmids":["37597489"],"is_preprint":false},{"year":2024,"finding":"Two TNNI3K variants (p.Leu577Phe and p.Pro742Leu) associated with congenital junctional ectopic tachycardia demonstrate substantially reduced kinase activity in autophosphorylation assays, linking loss of kinase function to this arrhythmia.","method":"Autophosphorylation kinase assay, next-generation sequencing, co-segregation analysis","journal":"Clinical genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — autophosphorylation assay with co-segregation, single lab, limited family sizes","pmids":["38424693"],"is_preprint":false},{"year":2024,"finding":"A naturally occurring polymorphism in the canine Tnni3k gene (prevalent in West Highland White Terriers) eliminates Tnni3k kinase activity, demonstrating that natural loss-of-kinase-function alleles exist across species.","method":"In vitro kinase assay of canine Tnni3k polymorphic variant","journal":"microPublication biology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — direct kinase assay, single variant, single lab","pmids":["38828440"],"is_preprint":false},{"year":2026,"finding":"Tnni3k kinase activity is cardioprotective during acute CVB3 viral myocarditis: Tnni3k knockout and kinase-dead knock-in mice show increased cardiac inflammation and macrophage infiltration compared to wild-type, while long-term damage is comparable.","method":"Tnni3k knockout and kinase-dead knock-in mouse models, CVB3 infection, histological quantification of inflammation and macrophage infiltration","journal":"Journal of cardiovascular development and disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two independent genetic alleles (null and kinase-dead) producing same acute inflammatory phenotype; single lab","pmids":["41745317"],"is_preprint":false}],"current_model":"TNNI3K is a cardiomyocyte-specific dual-specificity (Tyr and Ser/Thr) kinase that localizes to the sarcomere Z disc, where it phosphorylates cardiac troponin I (at Ser43/Thr143 or Ser22/Ser23) to modulate myofilament contractility; its kinase activity (negatively regulated by the C-terminal Ser-rich domain and by the binding partner AOP-1, and positively dependent on ANK-domain-mediated dimerization) drives p38 MAPK-dependent mitochondrial oxidative stress and cardiomyocyte death during ischemia/reperfusion injury, prolongs atrioventricular conduction (PR interval), restrains mononuclear diploid cardiomyocyte frequency, supports contractile reserve via PKA signaling, and is cardioprotective during viral myocarditis; gain-of-function variants enhance autophosphorylation and cause arrhythmia/cardiomyopathy, while loss-of-function causes concentric remodeling, impaired contractility, and arrhythmia, with transcription controlled by MEF2C binding to the promoter."},"narrative":{"mechanistic_narrative":"TNNI3K is a cardiomyocyte-enriched dual-specificity (Tyr and Ser/Thr) kinase that functions at the sarcomere to tune myofilament contractility, cardiac geometry, conduction, and stress responses [PMID:23085512, PMID:33084860]. Its kinase activity, rather than mere protein abundance, drives cardiac remodeling—including sarcomere length reduction and titin isoform changes—as established by kinase-dead transgenic comparison, and the protein localizes to the sarcomere Z disc [PMID:23085512]. Activity is autoregulated: dimerization and the N-terminal ANK domain are required for autophosphorylation, while the C-terminal Ser-rich domain and the binding partner AOP-1 negatively regulate catalysis [PMID:17660584, PMID:18205602]. TNNI3K physically binds cardiac troponin I and phosphorylates it (at Ser43/Thr143 and Ser22/Ser23), enhancing cardiomyocyte contraction, and supports contractile reserve through PKA signaling [PMID:23369981, PMID:23472207, PMID:33084860]. Cardiac-specific transcription is governed by MEF2C binding to a critical MEF2 site in the promoter [PMID:18021318]. The kinase has context-dependent roles in disease: it promotes ischemia/reperfusion injury by increasing mitochondrial superoxide and activating p38 MAPK, such that pharmacologic inhibition at reperfusion reduces infarct size, yet it is cardioprotective during acute viral myocarditis [PMID:24132636, PMID:41745317]. TNNI3K also modulates atrioventricular conduction and restrains the frequency of mononuclear diploid cardiomyocytes by acting at distinct cell-cycle stages [PMID:23236294, PMID:31589606, PMID:37597489]. Human variants establish a bidirectional genotype-phenotype relationship: gain-of-function alleles that enhance autophosphorylation cause supraventricular tachycardia, conduction disease, and dilated cardiomyopathy, whereas loss-of-kinase-function alleles cause concentric ventricular remodeling, impaired contractility, and junctional ectopic tachycardia [PMID:30010057, PMID:33084860, PMID:37199186, PMID:38424693]. Crystal structures of the kinase domain bound to small-molecule inhibitors have enabled structure-guided design of selective, cardioprotective compounds [PMID:26355916, PMID:34699203].","teleology":[{"year":2007,"claim":"Established the basic enzymatic identity and intramolecular regulation of TNNI3K, defining it as an autoregulated dual-specificity kinase before any substrate or pathway was known.","evidence":"In vitro kinase assays with domain deletion/mutagenesis","pmids":["17660584"],"confidence":"Medium","gaps":["No physiological substrate identified","Activation mechanism of dimerization not structurally resolved"]},{"year":2007,"claim":"Identified AOP-1 as a direct ANK-domain partner that inhibits kinase activity, providing the first regulatory protein interaction.","evidence":"Yeast two-hybrid, in vitro binding, co-IP, and kinase assay","pmids":["18205602"],"confidence":"Medium","gaps":["In vivo relevance of AOP-1 inhibition untested","Stoichiometry and structural basis of inhibition unknown"]},{"year":2007,"claim":"Explained the cardiac-restricted expression of TNNI3K by identifying MEF2C as the critical transcriptional driver at its promoter.","evidence":"Promoter mutational analysis, EMSA supershift, co-transfection","pmids":["18021318"],"confidence":"Medium","gaps":["Upstream regulators of MEF2C-driven expression not defined","Does not address post-transcriptional control"]},{"year":2009,"claim":"Linked TNNI3K dosage to cardiac disease susceptibility in vivo, showing expression level modulates cardiomyopathy progression across genetic backgrounds.","evidence":"Double-transgenic and pressure-overload mouse models with genetic mapping","pmids":["19763165"],"confidence":"High","gaps":["Molecular substrate driving disease acceleration not identified at this stage","Distinction between kinase activity and abundance not yet resolved"]},{"year":2012,"claim":"Demonstrated that kinase activity itself, not overexpression, drives remodeling, and localized the protein to the Z disc—anchoring TNNI3K function to the sarcomere.","evidence":"Kinase-dead vs. wild-type transgenic mice, proteomics, immunofluorescence","pmids":["23085512"],"confidence":"High","gaps":["Direct substrate at the Z disc not proven in this study","Mechanism linking phosphorylation to titin isoform change unknown"]},{"year":2012,"claim":"Identified TNNI3K as a quantitative modulator of atrioventricular conduction, connecting it to a discrete electrophysiological phenotype.","evidence":"Expression QTL mapping and ECG in congenic/transgenic mice","pmids":["23236294"],"confidence":"High","gaps":["Molecular target mediating PR prolongation not defined","Cell type responsible (conduction system vs. myocyte) not resolved"]},{"year":2013,"claim":"Identified cardiac troponin I as a direct substrate and binding partner, establishing the molecular link between TNNI3K and myofilament contractility.","evidence":"Co-IP, yeast two-hybrid, in vitro and in vivo phosphorylation, cardiomyocyte contraction measurements","pmids":["23369981","23472207"],"confidence":"Medium","gaps":["Reported phosphosite assignments differ between studies (Ser43/Thr143 vs Ser22/Ser23)","Single-lab findings without independent reciprocal validation"]},{"year":2013,"claim":"Defined a pathological role in ischemia/reperfusion injury via mitochondrial superoxide and p38 MAPK, and validated pharmacologic inhibition as cardioprotective.","evidence":"Small-molecule inhibition in mouse I/R model with superoxide, p38, and infarct readouts","pmids":["24132636"],"confidence":"High","gaps":["Direct substrate linking TNNI3K to mitochondrial superoxide not identified","Mechanism coupling kinase to p38 activation unresolved"]},{"year":2014,"claim":"Provided first human genetic evidence implicating a TNNI3K missense mutation in disease through a dominant-negative loss-of-function mechanism.","evidence":"In vitro aggregation assay, in silico docking, human ventricular IHC","pmids":["24925317"],"confidence":"Medium","gaps":["Dominant-negative mechanism inferred, not directly demonstrated","Limited to one carrier's tissue"]},{"year":2015,"claim":"Delivered the first crystal structure of the kinase domain bound to an inhibitor, enabling rational drug design against TNNI3K.","evidence":"X-ray crystallography of TNNI3K-inhibitor complex","pmids":["26355916"],"confidence":"High","gaps":["Structure of full-length protein and ANK domain not solved","Active-state/dimer structure not determined"]},{"year":2019,"claim":"Showed kinase activity is required for TNNI3K to restrain mononuclear diploid cardiomyocyte frequency, connecting it to cardiomyocyte ploidy and oxidative stress.","evidence":"Kinase-dead knock-in mice, cardiomyocyte ploidy analysis, in vitro kinase assay of human variants","pmids":["31589606"],"confidence":"High","gaps":["Substrate controlling ploidy not identified","Mechanistic convergence with oxidative stress not detailed"]},{"year":2021,"claim":"Established that loss of kinase activity causes concentric remodeling and reduced contractile reserve via impaired PKA signaling, revealing a beneficial physiological role distinct from its injury-promoting role.","evidence":"Knockout and knock-in (K489R, I686T) mouse models with contractility, calcium, and PKA assays","pmids":["33084860"],"confidence":"High","gaps":["Direct link between TNNI3K and PKA pathway not biochemically defined","Substrate mediating contractile reserve unclear"]},{"year":2021,"claim":"Achieved selective inhibitor design over related kinases using diarylurea co-crystal structures, yielding a cardioprotective tool compound.","evidence":"X-ray crystallography of inhibitor complexes, structure-based chemistry, mouse I/R model","pmids":["34699203"],"confidence":"Medium","gaps":["Primarily medicinal-chemistry; in vivo efficacy limited validation","Long-term safety/specificity not addressed"]},{"year":2023,"claim":"Consolidated the bidirectional genotype-phenotype model, showing gain-of-autophosphorylation variants cause DCM/arrhythmia while a depleted-activity variant is benign.","evidence":"Autophosphorylation assays, NGS, co-segregation, UK Biobank burden testing","pmids":["37199186"],"confidence":"Medium","gaps":["Mechanism by which enhanced autophosphorylation drives disease not resolved","Single-lab functional assays"]},{"year":2023,"claim":"Refined the cardiomyocyte proliferation role by showing TNNI3K acts at both S-phase entry and cytokinesis.","evidence":"Single-cell analysis of ventricular cardiomyocytes with Tnni3k knockout","pmids":["37597489"],"confidence":"Medium","gaps":["Substrate/effector at each cell-cycle stage unknown","Single method, single lab"]},{"year":2024,"claim":"Extended the loss-of-function arm of the genotype-phenotype map to congenital junctional ectopic tachycardia via reduced-activity variants, and showed natural loss-of-kinase alleles occur across species.","evidence":"Autophosphorylation assays of human and canine variants with co-segregation","pmids":["38424693","38828440"],"confidence":"Medium","gaps":["Limited family sizes","Mechanistic link from reduced activity to specific arrhythmia not established"]},{"year":2026,"claim":"Revealed a cardioprotective role for kinase activity in acute viral myocarditis, contrasting its injury-promoting role in I/R and underscoring context-dependent function.","evidence":"Knockout and kinase-dead knock-in mice with CVB3 infection and histological inflammation quantification","pmids":["41745317"],"confidence":"Medium","gaps":["Substrate mediating anti-inflammatory effect unknown","Why long-term damage is unaffected not explained"]},{"year":null,"claim":"The unifying biochemical mechanism that reconciles TNNI3K's opposing roles—injury-promoting in I/R yet protective in myocarditis and for contractile reserve—remains unresolved, as does how a single set of substrates produces both gain- and loss-of-function disease.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of the active dimer or ANK regulation","Substrates beyond cTnI driving mitochondrial, conduction, and ploidy phenotypes not identified","Mechanistic coupling of kinase activity to p38 and PKA pathways undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,5,7,8]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,5,7]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-397014","term_label":"Muscle contraction","supporting_discovery_ids":[7,14]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[9,14]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[13,17]}],"complexes":[],"partners":["TNNI3","AOP-1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q59H18","full_name":"Serine/threonine-protein kinase TNNI3K","aliases":["Cardiac ankyrin repeat kinase","Cardiac troponin I-interacting kinase","TNNI3-interacting kinase"],"length_aa":835,"mass_kda":92.9,"function":"May play a role in cardiac physiology","subcellular_location":"Nucleus; Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q59H18/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TNNI3K","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/TNNI3K","total_profiled":1310},"omim":[{"mim_id":"616117","title":"CARDIAC CONDUCTION DISEASE WITH OR WITHOUT CARDIOMYOPATHY 1; CCCM1","url":"https://www.omim.org/entry/616117"},{"mim_id":"613932","title":"TNNI3-INTERACTING KINASE; TNNI3K","url":"https://www.omim.org/entry/613932"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"heart muscle","ntpm":54.6}],"url":"https://www.proteinatlas.org/search/TNNI3K"},"hgnc":{"alias_symbol":["CARK"],"prev_symbol":[]},"alphafold":{"accession":"Q59H18","domains":[{"cath_id":"3.30.200.20","chopping":"445-541","consensus_level":"high","plddt":84.3273,"start":445,"end":541},{"cath_id":"1.10.510.10","chopping":"554-727","consensus_level":"high","plddt":86.3797,"start":554,"end":727}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q59H18","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q59H18-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q59H18-F1-predicted_aligned_error_v6.png","plddt_mean":79.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TNNI3K","jax_strain_url":"https://www.jax.org/strain/search?query=TNNI3K"},"sequence":{"accession":"Q59H18","fasta_url":"https://rest.uniprot.org/uniprotkb/Q59H18.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q59H18/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q59H18"}},"corpus_meta":[{"pmid":"19763165","id":"PMC_19763165","title":"Tnni3k modifies disease progression in murine models of cardiomyopathy.","date":"2009","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/19763165","citation_count":77,"is_preprint":false},{"pmid":"24132636","id":"PMC_24132636","title":"Inhibition of the cardiomyocyte-specific kinase TNNI3K limits oxidative stress, injury, and adverse remodeling in the ischemic heart.","date":"2013","source":"Science translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/24132636","citation_count":57,"is_preprint":false},{"pmid":"21525387","id":"PMC_21525387","title":"Quantitative trait locus analysis, pathway analysis, and consomic mapping show genetic variants of Tnni3k, Fpgt, or H28 control susceptibility to viral myocarditis.","date":"2011","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/21525387","citation_count":48,"is_preprint":false},{"pmid":"24925317","id":"PMC_24925317","title":"TNNI3K mutation in familial syndrome of conduction system disease, atrial tachyarrhythmia and dilated cardiomyopathy.","date":"2014","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/24925317","citation_count":46,"is_preprint":false},{"pmid":"23236294","id":"PMC_23236294","title":"Dissection of a quantitative trait locus for PR interval duration identifies Tnni3k as a novel modulator of cardiac conduction.","date":"2012","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23236294","citation_count":42,"is_preprint":false},{"pmid":"23085512","id":"PMC_23085512","title":"Overexpression of TNNI3K, a cardiac-specific MAPKKK, promotes cardiac dysfunction.","date":"2012","source":"Journal of molecular and cellular cardiology","url":"https://pubmed.ncbi.nlm.nih.gov/23085512","citation_count":37,"is_preprint":false},{"pmid":"26355916","id":"PMC_26355916","title":"Identification of Purines and 7-Deazapurines as Potent and Selective Type I Inhibitors of Troponin I-Interacting Kinase (TNNI3K).","date":"2015","source":"Journal of medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/26355916","citation_count":36,"is_preprint":false},{"pmid":"31589606","id":"PMC_31589606","title":"Tnni3k alleles influence ventricular mononuclear diploid cardiomyocyte frequency.","date":"2019","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/31589606","citation_count":30,"is_preprint":false},{"pmid":"18552163","id":"PMC_18552163","title":"Overexpression of TNNI3K, a cardiac-specific MAP kinase, promotes P19CL6-derived cardiac myogenesis and prevents myocardial infarction-induced injury.","date":"2008","source":"American journal of physiology. 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Biokhimiia","url":"https://pubmed.ncbi.nlm.nih.gov/18205602","citation_count":15,"is_preprint":false},{"pmid":"27246618","id":"PMC_27246618","title":"GSK114: A selective inhibitor for elucidating the biological role of TNNI3K.","date":"2016","source":"Bioorganic & medicinal chemistry letters","url":"https://pubmed.ncbi.nlm.nih.gov/27246618","citation_count":14,"is_preprint":false},{"pmid":"28135716","id":"PMC_28135716","title":"Overexpression of Cardiac-Specific Kinase TNNI3K Promotes Mouse Embryonic Stem Cells Differentiation into Cardiomyocytes.","date":"2017","source":"Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/28135716","citation_count":11,"is_preprint":false},{"pmid":"32529721","id":"PMC_32529721","title":"Identification of a nonsense mutation in TNNI3K associated with cardiac conduction disease.","date":"2020","source":"Journal of clinical laboratory analysis","url":"https://pubmed.ncbi.nlm.nih.gov/32529721","citation_count":11,"is_preprint":false},{"pmid":"32272798","id":"PMC_32272798","title":"New Insights into 4-Anilinoquinazolines as Inhibitors of Cardiac Troponin I-Interacting Kinase (TNNi3K).","date":"2020","source":"Molecules (Basel, Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/32272798","citation_count":10,"is_preprint":false},{"pmid":"33084860","id":"PMC_33084860","title":"The prevalent I686T human variant and loss-of-function mutations in the cardiomyocyte-specific kinase gene TNNI3K cause adverse contractility and concentric remodeling in mice.","date":"2021","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/33084860","citation_count":10,"is_preprint":false},{"pmid":"34440456","id":"PMC_34440456","title":"A Novel Missense Mutation in TNNI3K Causes Recessively Inherited Cardiac Conduction Disease in a Consanguineous Pakistani Family.","date":"2021","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/34440456","citation_count":10,"is_preprint":false},{"pmid":"37597489","id":"PMC_37597489","title":"Tnni3k influences cardiomyocyte S-phase activity and proliferation.","date":"2023","source":"Journal of molecular and cellular cardiology","url":"https://pubmed.ncbi.nlm.nih.gov/37597489","citation_count":9,"is_preprint":false},{"pmid":"30334579","id":"PMC_30334579","title":"Over-expression of TNNI3K is associated with early-stage carcinogenesis of cholangiocarcinoma.","date":"2018","source":"Molecular carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/30334579","citation_count":8,"is_preprint":false},{"pmid":"34699203","id":"PMC_34699203","title":"Identification of Diarylurea Inhibitors of the Cardiac-Specific Kinase TNNI3K by Designing Selectivity Against VEGFR2, p38α, and B-Raf.","date":"2021","source":"Journal of medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/34699203","citation_count":6,"is_preprint":false},{"pmid":"35274013","id":"PMC_35274013","title":"Whole-Exome Sequencing Identifies a Novel Variant (c.1538T > C) of TNNI3K in Arrhythmogenic Right Ventricular Cardiomyopathy.","date":"2022","source":"Frontiers in cardiovascular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35274013","citation_count":6,"is_preprint":false},{"pmid":"37199186","id":"PMC_37199186","title":"Genetic Burden of TNNI3K in Diagnostic Testing of Patients With Dilated Cardiomyopathy and Supraventricular Arrhythmias.","date":"2023","source":"Circulation. Genomic and precision medicine","url":"https://pubmed.ncbi.nlm.nih.gov/37199186","citation_count":5,"is_preprint":false},{"pmid":"38424693","id":"PMC_38424693","title":"Reduced kinase function in two ultra-rare TNNI3K variants in families with congenital junctional ectopic tachycardia.","date":"2024","source":"Clinical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/38424693","citation_count":3,"is_preprint":false},{"pmid":"19925440","id":"PMC_19925440","title":"TNNI3K could be a novel molecular target for the treatment of cardiac diseases.","date":"2009","source":"Recent patents on cardiovascular drug discovery","url":"https://pubmed.ncbi.nlm.nih.gov/19925440","citation_count":2,"is_preprint":false},{"pmid":"40134720","id":"PMC_40134720","title":"A de novo TNNI3K variant aggravates the pathogenicity of DMD-associated early-onset cardiomyopathy: a case report.","date":"2025","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/40134720","citation_count":2,"is_preprint":false},{"pmid":"38828440","id":"PMC_38828440","title":"A kinase-dead natural polymorphism in the canine Tnni3k gene.","date":"2024","source":"microPublication biology","url":"https://pubmed.ncbi.nlm.nih.gov/38828440","citation_count":1,"is_preprint":false},{"pmid":"30488312","id":"PMC_30488312","title":"Correction to: ACE2, CALM3 and TNNI3K polymorphisms as potential disease modifiers in hypertrophic and dilated cardiomyopathies.","date":"2019","source":"Molecular and cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/30488312","citation_count":1,"is_preprint":false},{"pmid":"40974855","id":"PMC_40974855","title":"Design and synthesis of 4-azaindoles derivatives: targeting the cardiac troponin I-interacting kinase (TNNI3K).","date":"2025","source":"Bioorganic & medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/40974855","citation_count":0,"is_preprint":false},{"pmid":"41745317","id":"PMC_41745317","title":"Tnni3k Is Cardioprotective in Viral Myocarditis.","date":"2026","source":"Journal of cardiovascular development and disease","url":"https://pubmed.ncbi.nlm.nih.gov/41745317","citation_count":0,"is_preprint":false},{"pmid":"40904527","id":"PMC_40904527","title":"Clockwise bundle branch re-entrant ventricular tachycardia in a teenage patient as the first manifestation of dilated cardiomyopathy associated with the p.Ile512Leu TNNI3k variant: a case report.","date":"2025","source":"European heart journal. Case reports","url":"https://pubmed.ncbi.nlm.nih.gov/40904527","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":20235,"output_tokens":4984,"usd":0.067733,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":13180,"output_tokens":4655,"usd":0.091137,"stage2_stop_reason":"end_turn"},"total_usd":0.15887,"stage1_batch_id":"msgbatch_017qqVz33Ga63SCDwzb35XPb","stage2_batch_id":"msgbatch_01Scr2Ei9x4HJMiRGxwrmvLK","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"TNNI3K exhibits dual-specificity kinase activity (Tyr and Ser/Thr), forms dimers or oligomers required for activation, the C-terminal Ser-rich domain negatively regulates kinase activity, and the N-terminal ANK domain is necessary for autophosphorylation.\",\n      \"method\": \"In vitro kinase assay, domain deletion/mutagenesis analysis\",\n      \"journal\": \"General physiology and biophysics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro kinase assay with domain mutagenesis, single lab, single study\",\n      \"pmids\": [\"17660584\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Antioxidant protein 1 (AOP-1) interacts with the ANK motif of TNNI3K (identified by yeast two-hybrid, confirmed by in vitro binding assay and co-expression), co-localizes with TNNI3K, and inhibits TNNI3K kinase activity in vitro.\",\n      \"method\": \"Yeast two-hybrid screen, in vitro binding assay, co-immunoprecipitation, confocal immunofluorescence, in vitro kinase assay\",\n      \"journal\": \"Biochemistry. Biokhimiia\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal binding confirmed by multiple orthogonal methods (Y2H, in vitro binding, co-IP, kinase assay), single lab\",\n      \"pmids\": [\"18205602\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"MEF2C binds to the TNNI3K/CARK promoter at a conserved MEF2 site that is the most critical cis-acting element for cardiac-specific transcription; MEF2C antisense reduces CARK transcript levels.\",\n      \"method\": \"Promoter truncation/mutational analysis, EMSA (supershift), co-transfection assays\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — EMSA supershift plus functional co-transfection and mutational analysis, single lab\",\n      \"pmids\": [\"18021318\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"TNNI3K overexpression promotes differentiation of P19CL6 cells into cardiomyocytes, suppresses p38/JNK-mediated apoptosis (reduced annexin-V+ cells, Bax, and p38/JNK phosphorylation), and improves cardiac function in a mouse myocardial infarction model.\",\n      \"method\": \"Cell transfection/overexpression, flow cytometry (apoptosis), Western blot (p38/JNK phosphorylation), intramyocardial cell injection in MI mouse model\",\n      \"journal\": \"American journal of physiology. Heart and circulatory physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods in vitro and in vivo, single lab\",\n      \"pmids\": [\"18552163\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"TNNI3K expression accelerates cardiac dysfunction in the Calsequestrin transgenic mouse model of cardiomyopathy and in a pressure-overload model; high TNNI3K transcript levels correlate with increased disease susceptibility, while a splice-activating intronic SNP causes nonsense-mediated decay and loss of detectable protein in resistant strains.\",\n      \"method\": \"Transgenic mouse models (TNNI3K/Csq double transgenic, pressure overload), genetic mapping, RT-PCR, Western blot\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple transgenic and congenic mouse models with defined phenotypic readouts, replicated across two cardiac disease models\",\n      \"pmids\": [\"19763165\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"TNNI3K is a dual-function kinase (Tyr and Ser/Thr activity) in vivo; its kinase activity (not merely overexpression) drives cardiac remodeling including sarcomere length reduction and titin isoform changes, as shown by kinase-dead transgenic mice lacking these effects; TNNI3K protein localizes to the sarcomere Z disc.\",\n      \"method\": \"Transgenic mice (wild-type vs. kinase-dead TNNI3K), in vitro kinase assay, proteomics, immunofluorescence/immunostaining, pressure-overload model\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — kinase-dead vs. wild-type transgenic comparison with defined molecular phenotypes, in vitro kinase assay, subcellular localization; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"23085512\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Tnni3k mRNA level positively correlates with PR interval duration in mice; overexpression of hTNNI3K in DBA/2J mice prolongs the PR interval, identifying Tnni3k as a modulator of atrio-ventricular conduction.\",\n      \"method\": \"Expression QTL mapping, ECG measurements in congenic and transgenic mouse lines, correlation analysis of mRNA and PR interval\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple independent mouse strains/models (transgenic overexpression + congenic lines) with direct ECG phenotyping, replicated across genetic backgrounds\",\n      \"pmids\": [\"23236294\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"TNNI3K phosphorylates cardiac troponin I (cTnI) at Ser43 and Thr143 in vitro and in adult rat cardiomyocytes (not at Ser23/24 or Ser44); TNNI3K overexpression increases and knockdown decreases cTnI phosphorylation at these sites; increased TNNI3K/cTnI interaction enhances cardiomyocyte contraction.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, adult rat cardiomyocyte overexpression/knockdown, cardiomyocyte contraction measurements\",\n      \"journal\": \"Brazilian journal of medical and biological research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Weak — in vitro kinase assay with site identification plus cellular KD/OE with functional readout, single lab\",\n      \"pmids\": [\"23369981\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"TNNI3K physically interacts with cTnI (confirmed by co-immunoprecipitation and yeast two-hybrid), induces cTnI phosphorylation at Ser22/Ser23 in vivo and in vitro, and promotes concentric cardiac hypertrophy with enhanced cardiac function in transgenic mice; phosphoamino acid analysis confirmed TNNI3K is a protein-tyrosine kinase.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, in vivo and in vitro phosphorylation assays, transgenic mouse echocardiography\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal binding (Y2H + Co-IP) plus in vivo phosphorylation with transgenic model, single lab\",\n      \"pmids\": [\"23472207\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"TNNI3K promotes ischemia/reperfusion injury through increased mitochondrial superoxide production, impaired mitochondrial function, and p38 MAPK activation; pharmacologic TNNI3K inhibition reduces mitochondrial superoxide, p38 activation, and infarct size when delivered at reperfusion.\",\n      \"method\": \"Small-molecule inhibitor treatment in mouse I/R model, mitochondrial superoxide measurement, p38 MAPK phosphorylation assay, infarct size measurement, echocardiography\",\n      \"journal\": \"Science translational medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal mechanistic readouts (superoxide, mitochondrial function, p38, infarct size) in an in vivo model with pharmacologic intervention replicated with multiple inhibitor compounds\",\n      \"pmids\": [\"24132636\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"A missense mutation G526D in the TNNI3K kinase domain causes abnormal peptide aggregation in vitro; in silico docking predicts altered but energetically favorable dimerization; ventricular tissue from a carrier shows reduced TNNI3K protein staining with nuclear/sarcoplasmic inclusions, implicating dominant-negative loss-of-function.\",\n      \"method\": \"In vitro aggregation assay, in silico docking, immunohistochemistry of human ventricular tissue\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — in vitro aggregation assay and human tissue IHC, supported by computational modeling; single study, limited experimental validation\",\n      \"pmids\": [\"24925317\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"X-ray crystal structure of a purine inhibitor (compound 1) bound to TNNI3K confirmed Type I binding mode to the kinase domain, enabling rational structure-guided inhibitor design and delineation of structure-activity relationships.\",\n      \"method\": \"X-ray crystallography of TNNI3K-inhibitor complex\",\n      \"journal\": \"Journal of medicinal chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure determination with functional SAR validation, single lab but rigorous structural method\",\n      \"pmids\": [\"26355916\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The TNNI3K p.Glu768Lys variant displays enhanced kinase autophosphorylation activity compared to wild-type TNNI3K, and co-segregates with disease in 23 affected individuals across 3 independent families presenting with supraventricular tachycardia, conduction disturbance, and DCM.\",\n      \"method\": \"Autophosphorylation kinase assay, next-generation sequencing, co-segregation analysis\",\n      \"journal\": \"Heart rhythm\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — autophosphorylation assay plus multi-family co-segregation; functionally replicated across 3 families, single lab\",\n      \"pmids\": [\"30010057\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Tnni3k function requires its kinase activity (shown by kinase-dead allele in mice); Tnni3k regulates the frequency of mononuclear diploid cardiomyocytes and converges with oxidative stress in this regulation; common human TNNI3K kinase domain variants substantially compromise kinase activity in vitro.\",\n      \"method\": \"In vitro kinase assay of human variants, kinase-dead knock-in mouse model, cardiomyocyte ploidy analysis\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro kinase assay of multiple human variants plus genetic knock-in mouse with defined cellular phenotype, multiple orthogonal methods in single rigorous study\",\n      \"pmids\": [\"31589606\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Loss of TNNI3K kinase activity (null allele, kinase-dead K489R, or hypomorphic I686T variant) causes concentric ventricular remodeling, impaired cardiomyocyte contractility, defective calcium dynamics, and reduced PKA signaling in response to isoproterenol in cultured cardiomyocytes, demonstrating a beneficial role for TNNI3K in maintaining normal cardiac geometry and contractile reserve.\",\n      \"method\": \"Tnni3k knockout and knock-in mouse models, echocardiography, cardiomyocyte contractility and calcium imaging, PKA signaling assay in culture\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — three independent genetic alleles producing same phenotype, multiple cellular readouts including contractility, calcium, and PKA signaling; single lab but multiple orthogonal approaches\",\n      \"pmids\": [\"33084860\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"X-ray crystal structures of TNNI3K with diarylurea inhibitors enabled structure-based design of selective TNNI3K inhibitors over VEGFR2, p38α, and B-Raf; a tool compound (GSK329) showed cardioprotective effects in a mouse I/R model.\",\n      \"method\": \"X-ray crystallography of TNNI3K-inhibitor complexes, structure-based medicinal chemistry, in vivo I/R mouse model\",\n      \"journal\": \"Journal of medicinal chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — crystal structure and in vivo model, but primarily a medicinal chemistry study; single lab\",\n      \"pmids\": [\"34699203\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Novel TNNI3K variants p.Ile512Thr and p.His592Tyr show increased autophosphorylation activity and co-segregate with DCM, conduction disease, and supraventricular tachycardia; a likely benign variant (p.Arg556_Asn590del) shows depleted autophosphorylation, suggesting enhanced autophosphorylation drives pathogenicity.\",\n      \"method\": \"TNNI3K autophosphorylation assay, next-generation sequencing, co-segregation analysis, UK Biobank burden testing\",\n      \"journal\": \"Circulation. Genomic and precision medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — autophosphorylation assay plus co-segregation in independent families and population-level burden testing; single lab\",\n      \"pmids\": [\"37199186\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Tnni3k influences both early S-phase entry and the completion of cell division (cytokinesis) in cardiomyocytes, demonstrating roles at distinct stages of the cell cycle.\",\n      \"method\": \"Retrospective single-cell analysis of ventricular cardiomyocyte suspensions to identify post-division cells, genetic loss-of-function (Tnni3k knockout)\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — defined cellular phenotype with loss-of-function model, single lab, single method\",\n      \"pmids\": [\"37597489\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Two TNNI3K variants (p.Leu577Phe and p.Pro742Leu) associated with congenital junctional ectopic tachycardia demonstrate substantially reduced kinase activity in autophosphorylation assays, linking loss of kinase function to this arrhythmia.\",\n      \"method\": \"Autophosphorylation kinase assay, next-generation sequencing, co-segregation analysis\",\n      \"journal\": \"Clinical genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — autophosphorylation assay with co-segregation, single lab, limited family sizes\",\n      \"pmids\": [\"38424693\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"A naturally occurring polymorphism in the canine Tnni3k gene (prevalent in West Highland White Terriers) eliminates Tnni3k kinase activity, demonstrating that natural loss-of-kinase-function alleles exist across species.\",\n      \"method\": \"In vitro kinase assay of canine Tnni3k polymorphic variant\",\n      \"journal\": \"microPublication biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — direct kinase assay, single variant, single lab\",\n      \"pmids\": [\"38828440\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Tnni3k kinase activity is cardioprotective during acute CVB3 viral myocarditis: Tnni3k knockout and kinase-dead knock-in mice show increased cardiac inflammation and macrophage infiltration compared to wild-type, while long-term damage is comparable.\",\n      \"method\": \"Tnni3k knockout and kinase-dead knock-in mouse models, CVB3 infection, histological quantification of inflammation and macrophage infiltration\",\n      \"journal\": \"Journal of cardiovascular development and disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two independent genetic alleles (null and kinase-dead) producing same acute inflammatory phenotype; single lab\",\n      \"pmids\": [\"41745317\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TNNI3K is a cardiomyocyte-specific dual-specificity (Tyr and Ser/Thr) kinase that localizes to the sarcomere Z disc, where it phosphorylates cardiac troponin I (at Ser43/Thr143 or Ser22/Ser23) to modulate myofilament contractility; its kinase activity (negatively regulated by the C-terminal Ser-rich domain and by the binding partner AOP-1, and positively dependent on ANK-domain-mediated dimerization) drives p38 MAPK-dependent mitochondrial oxidative stress and cardiomyocyte death during ischemia/reperfusion injury, prolongs atrioventricular conduction (PR interval), restrains mononuclear diploid cardiomyocyte frequency, supports contractile reserve via PKA signaling, and is cardioprotective during viral myocarditis; gain-of-function variants enhance autophosphorylation and cause arrhythmia/cardiomyopathy, while loss-of-function causes concentric remodeling, impaired contractility, and arrhythmia, with transcription controlled by MEF2C binding to the promoter.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TNNI3K is a cardiomyocyte-enriched dual-specificity (Tyr and Ser/Thr) kinase that functions at the sarcomere to tune myofilament contractility, cardiac geometry, conduction, and stress responses [#5, #14]. Its kinase activity, rather than mere protein abundance, drives cardiac remodeling—including sarcomere length reduction and titin isoform changes—as established by kinase-dead transgenic comparison, and the protein localizes to the sarcomere Z disc [#5]. Activity is autoregulated: dimerization and the N-terminal ANK domain are required for autophosphorylation, while the C-terminal Ser-rich domain and the binding partner AOP-1 negatively regulate catalysis [#0, #1]. TNNI3K physically binds cardiac troponin I and phosphorylates it (at Ser43/Thr143 and Ser22/Ser23), enhancing cardiomyocyte contraction, and supports contractile reserve through PKA signaling [#7, #8, #14]. Cardiac-specific transcription is governed by MEF2C binding to a critical MEF2 site in the promoter [#2]. The kinase has context-dependent roles in disease: it promotes ischemia/reperfusion injury by increasing mitochondrial superoxide and activating p38 MAPK, such that pharmacologic inhibition at reperfusion reduces infarct size, yet it is cardioprotective during acute viral myocarditis [#9, #20]. TNNI3K also modulates atrioventricular conduction and restrains the frequency of mononuclear diploid cardiomyocytes by acting at distinct cell-cycle stages [#6, #13, #17]. Human variants establish a bidirectional genotype-phenotype relationship: gain-of-function alleles that enhance autophosphorylation cause supraventricular tachycardia, conduction disease, and dilated cardiomyopathy, whereas loss-of-kinase-function alleles cause concentric ventricular remodeling, impaired contractility, and junctional ectopic tachycardia [#12, #14, #16, #18]. Crystal structures of the kinase domain bound to small-molecule inhibitors have enabled structure-guided design of selective, cardioprotective compounds [#11, #15].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Established the basic enzymatic identity and intramolecular regulation of TNNI3K, defining it as an autoregulated dual-specificity kinase before any substrate or pathway was known.\",\n      \"evidence\": \"In vitro kinase assays with domain deletion/mutagenesis\",\n      \"pmids\": [\"17660584\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No physiological substrate identified\", \"Activation mechanism of dimerization not structurally resolved\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Identified AOP-1 as a direct ANK-domain partner that inhibits kinase activity, providing the first regulatory protein interaction.\",\n      \"evidence\": \"Yeast two-hybrid, in vitro binding, co-IP, and kinase assay\",\n      \"pmids\": [\"18205602\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo relevance of AOP-1 inhibition untested\", \"Stoichiometry and structural basis of inhibition unknown\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Explained the cardiac-restricted expression of TNNI3K by identifying MEF2C as the critical transcriptional driver at its promoter.\",\n      \"evidence\": \"Promoter mutational analysis, EMSA supershift, co-transfection\",\n      \"pmids\": [\"18021318\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Upstream regulators of MEF2C-driven expression not defined\", \"Does not address post-transcriptional control\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Linked TNNI3K dosage to cardiac disease susceptibility in vivo, showing expression level modulates cardiomyopathy progression across genetic backgrounds.\",\n      \"evidence\": \"Double-transgenic and pressure-overload mouse models with genetic mapping\",\n      \"pmids\": [\"19763165\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular substrate driving disease acceleration not identified at this stage\", \"Distinction between kinase activity and abundance not yet resolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Demonstrated that kinase activity itself, not overexpression, drives remodeling, and localized the protein to the Z disc—anchoring TNNI3K function to the sarcomere.\",\n      \"evidence\": \"Kinase-dead vs. wild-type transgenic mice, proteomics, immunofluorescence\",\n      \"pmids\": [\"23085512\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct substrate at the Z disc not proven in this study\", \"Mechanism linking phosphorylation to titin isoform change unknown\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified TNNI3K as a quantitative modulator of atrioventricular conduction, connecting it to a discrete electrophysiological phenotype.\",\n      \"evidence\": \"Expression QTL mapping and ECG in congenic/transgenic mice\",\n      \"pmids\": [\"23236294\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular target mediating PR prolongation not defined\", \"Cell type responsible (conduction system vs. myocyte) not resolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identified cardiac troponin I as a direct substrate and binding partner, establishing the molecular link between TNNI3K and myofilament contractility.\",\n      \"evidence\": \"Co-IP, yeast two-hybrid, in vitro and in vivo phosphorylation, cardiomyocyte contraction measurements\",\n      \"pmids\": [\"23369981\", \"23472207\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Reported phosphosite assignments differ between studies (Ser43/Thr143 vs Ser22/Ser23)\", \"Single-lab findings without independent reciprocal validation\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defined a pathological role in ischemia/reperfusion injury via mitochondrial superoxide and p38 MAPK, and validated pharmacologic inhibition as cardioprotective.\",\n      \"evidence\": \"Small-molecule inhibition in mouse I/R model with superoxide, p38, and infarct readouts\",\n      \"pmids\": [\"24132636\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct substrate linking TNNI3K to mitochondrial superoxide not identified\", \"Mechanism coupling kinase to p38 activation unresolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Provided first human genetic evidence implicating a TNNI3K missense mutation in disease through a dominant-negative loss-of-function mechanism.\",\n      \"evidence\": \"In vitro aggregation assay, in silico docking, human ventricular IHC\",\n      \"pmids\": [\"24925317\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Dominant-negative mechanism inferred, not directly demonstrated\", \"Limited to one carrier's tissue\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Delivered the first crystal structure of the kinase domain bound to an inhibitor, enabling rational drug design against TNNI3K.\",\n      \"evidence\": \"X-ray crystallography of TNNI3K-inhibitor complex\",\n      \"pmids\": [\"26355916\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure of full-length protein and ANK domain not solved\", \"Active-state/dimer structure not determined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showed kinase activity is required for TNNI3K to restrain mononuclear diploid cardiomyocyte frequency, connecting it to cardiomyocyte ploidy and oxidative stress.\",\n      \"evidence\": \"Kinase-dead knock-in mice, cardiomyocyte ploidy analysis, in vitro kinase assay of human variants\",\n      \"pmids\": [\"31589606\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Substrate controlling ploidy not identified\", \"Mechanistic convergence with oxidative stress not detailed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Established that loss of kinase activity causes concentric remodeling and reduced contractile reserve via impaired PKA signaling, revealing a beneficial physiological role distinct from its injury-promoting role.\",\n      \"evidence\": \"Knockout and knock-in (K489R, I686T) mouse models with contractility, calcium, and PKA assays\",\n      \"pmids\": [\"33084860\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct link between TNNI3K and PKA pathway not biochemically defined\", \"Substrate mediating contractile reserve unclear\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Achieved selective inhibitor design over related kinases using diarylurea co-crystal structures, yielding a cardioprotective tool compound.\",\n      \"evidence\": \"X-ray crystallography of inhibitor complexes, structure-based chemistry, mouse I/R model\",\n      \"pmids\": [\"34699203\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Primarily medicinal-chemistry; in vivo efficacy limited validation\", \"Long-term safety/specificity not addressed\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Consolidated the bidirectional genotype-phenotype model, showing gain-of-autophosphorylation variants cause DCM/arrhythmia while a depleted-activity variant is benign.\",\n      \"evidence\": \"Autophosphorylation assays, NGS, co-segregation, UK Biobank burden testing\",\n      \"pmids\": [\"37199186\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which enhanced autophosphorylation drives disease not resolved\", \"Single-lab functional assays\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Refined the cardiomyocyte proliferation role by showing TNNI3K acts at both S-phase entry and cytokinesis.\",\n      \"evidence\": \"Single-cell analysis of ventricular cardiomyocytes with Tnni3k knockout\",\n      \"pmids\": [\"37597489\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Substrate/effector at each cell-cycle stage unknown\", \"Single method, single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extended the loss-of-function arm of the genotype-phenotype map to congenital junctional ectopic tachycardia via reduced-activity variants, and showed natural loss-of-kinase alleles occur across species.\",\n      \"evidence\": \"Autophosphorylation assays of human and canine variants with co-segregation\",\n      \"pmids\": [\"38424693\", \"38828440\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Limited family sizes\", \"Mechanistic link from reduced activity to specific arrhythmia not established\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Revealed a cardioprotective role for kinase activity in acute viral myocarditis, contrasting its injury-promoting role in I/R and underscoring context-dependent function.\",\n      \"evidence\": \"Knockout and kinase-dead knock-in mice with CVB3 infection and histological inflammation quantification\",\n      \"pmids\": [\"41745317\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Substrate mediating anti-inflammatory effect unknown\", \"Why long-term damage is unaffected not explained\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The unifying biochemical mechanism that reconciles TNNI3K's opposing roles—injury-promoting in I/R yet protective in myocarditis and for contractile reserve—remains unresolved, as does how a single set of substrates produces both gain- and loss-of-function disease.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the active dimer or ANK regulation\", \"Substrates beyond cTnI driving mitochondrial, conduction, and ploidy phenotypes not identified\", \"Mechanistic coupling of kinase activity to p38 and PKA pathways undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 5, 7, 8]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 5, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-397014\", \"supporting_discovery_ids\": [7, 14]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [9, 14]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [13, 17]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"TNNI3\", \"AOP-1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"faith_supported":9,"faith_total":9,"faith_pct":100.0}}