{"gene":"TNNI3K","run_date":"2026-04-28T21:42:59","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 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 — in vitro kinase assay with domain mutagenesis, single lab","pmids":["17660584"],"is_preprint":false},{"year":2007,"finding":"AOP-1 (antioxidant protein 1) interacts with TNNI3K via its ANK motif domain and inhibits TNNI3K kinase activity; interaction confirmed by yeast two-hybrid, in vitro binding assay, co-expression in vivo, and confocal co-localization.","method":"Yeast two-hybrid, in vitro binding assay, co-immunoprecipitation, confocal immunofluorescence, in vitro kinase assay","journal":"Biochemistry. Biokhimiia","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods (Y2H, pulldown, co-IP, kinase assay), single lab","pmids":["18205602"],"is_preprint":false},{"year":2007,"finding":"MEF2C is an essential transcriptional regulator of TNNI3K/CARK expression; MEF2 binding sites in the minimal 151 bp promoter are the most critical cis-acting elements, confirmed by mutational analysis, EMSA supershift, and MEF2C antisense knockdown.","method":"Promoter truncation analysis, mutational analysis, EMSA (supershift), MEF2C antisense knockdown, co-transfection","journal":"Journal of cellular and molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods (EMSA, mutagenesis, antisense KD), single lab","pmids":["18021318"],"is_preprint":false},{"year":2008,"finding":"TNNI3K promotes cardiomyocyte differentiation from P19CL6 cells, enhances cardiac contractile function, and suppresses p38/JNK-mediated apoptosis, as shown by overexpression experiments and intramyocardial transplantation in myocardial infarction mice.","method":"Cell differentiation assay, overexpression in P19CL6 cells, intramyocardial transplantation in MI mouse model, measurement of beating frequency/contractile force, apoptosis assays (annexin-V, Bax, p38/JNK phosphorylation)","journal":"American journal of physiology. Heart and circulatory physiology","confidence":"Medium","confidence_rationale":"Tier 2 — multiple functional readouts in vitro and in vivo, single lab","pmids":["18552163"],"is_preprint":false},{"year":2009,"finding":"TNNI3K expression modifies cardiac disease progression: transgenic overexpression of TNNI3K combined with Calsequestrin transgene severely impairs systolic function and reduces survival; TNNI3K also accelerates disease in pressure-overload heart failure model.","method":"Transgenic mouse models (TNNI3K/Csq double transgenic, pressure-overload), echocardiography, survival analysis","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 — multiple in vivo genetic models with functional cardiac readouts, replicated across disease models","pmids":["19763165"],"is_preprint":false},{"year":2012,"finding":"Tnni3k expression level positively correlates with PR interval duration; overexpression of hTNNI3K in DBA/2J mice prolongs PR interval, identifying TNNI3K as a modulator of atrioventricular conduction.","method":"Expression QTL mapping, mRNA-PR interval correlation, transgenic overexpression, ECG measurement","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 — eQTL mapping plus transgenic functional validation, replicated in congenic mice","pmids":["23236294"],"is_preprint":false},{"year":2012,"finding":"TNNI3K is a dual Tyr and Ser/Thr kinase; its kinase activity drives cardiac remodeling including reduced sarcomere length and altered titin isoform composition; kinase-dead TNNI3K does not promote disease progression in pressure-overload model; TNNI3K protein localizes to the sarcomere Z disc.","method":"In vitro kinase assay, proteomics, transgenic mice (wild-type vs. kinase-dead TNNI3K), pressure-overload model, immunostaining with anti-TNNI3K antisera","journal":"Journal of molecular and cellular cardiology","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro kinase assay + kinase-dead transgenic mice + localization, multiple orthogonal methods","pmids":["23085512"],"is_preprint":false},{"year":2013,"finding":"TNNI3K interacts with cardiac troponin I (cTnI) and phosphorylates cTnI at Ser43 and Thr143 (but not Ser23/24 or Ser44) in vitro; overexpression of rTNNI3K in adult rat cardiomyocytes increases cTnI phosphorylation at these sites and enhances cardiomyocyte contraction, while knockdown reduces both.","method":"Co-immunoprecipitation, in vitro kinase assay with site-specific antibodies, overexpression/knockdown in adult rat ventricular myocytes, cardiomyocyte contraction measurement","journal":"Brazilian journal of medical and biological research","confidence":"Medium","confidence_rationale":"Tier 1-2 — in vitro kinase assay + co-IP + cellular overexpression/KD, single lab","pmids":["23369981"],"is_preprint":false},{"year":2013,"finding":"TNNI3K overexpression in transgenic mice promotes physiological concentric cardiac hypertrophy with enhanced function; yeast two-hybrid and co-immunoprecipitation identified cTnI as a TNNI3K target; TNNI3K induces cTnI phosphorylation at Ser22/Ser23 in vivo and in vitro; phosphoamino acid analysis confirms TNNI3K is a protein-tyrosine kinase.","method":"Transgenic mouse model, echocardiography, yeast two-hybrid, co-immunoprecipitation, in vitro kinase assay, phosphoamino acid analysis","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods including in vivo, Y2H, co-IP, and in vitro kinase assay","pmids":["23472207"],"is_preprint":false},{"year":2013,"finding":"TNNI3K promotes ischemia/reperfusion injury through increased mitochondrial superoxide production and impaired mitochondrial function, acting largely via p38 MAPK activation; pharmacologic TNNI3K inhibition reduces mitochondrial superoxide, p38 activation, and infarct size.","method":"Mouse I/R injury model, mitochondrial superoxide measurement, p38 MAPK phosphorylation assays, small-molecule TNNI3K inhibitors, cardiac function assessment","journal":"Science translational medicine","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal in vivo and mechanistic readouts, inhibitor pharmacology corroborating genetic findings","pmids":["24132636"],"is_preprint":false},{"year":2014,"finding":"A TNNI3K G526D missense mutation in the kinase domain causes abnormal peptide aggregation in vitro; in silico docking models predict altered dimerization; ventricular tissue from carriers shows reduced TNNI3K protein with amorphous nuclear and sarcoplasmic inclusions, indicating dominant-negative loss of function.","method":"In vitro peptide aggregation assay, in silico molecular docking, immunohistochemistry of human ventricular tissue","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2-3 — in vitro aggregation plus patient tissue histopathology, single study","pmids":["24925317"],"is_preprint":false},{"year":2015,"finding":"X-ray crystal structure of TNNI3K bound to a purine-based inhibitor confirmed Type I binding mode and elucidated the kinase active site architecture, enabling structure-activity relationship analysis and design of potent selective inhibitors.","method":"X-ray crystallography of TNNI3K-inhibitor complex","journal":"Journal of medicinal chemistry","confidence":"High","confidence_rationale":"Tier 1 — crystal structure directly resolving active site","pmids":["26355916"],"is_preprint":false},{"year":2018,"finding":"The TNNI3K p.Glu768Lys variant displays enhanced kinase autophosphorylation activity, consistent with a gain-of-function mechanism underlying familial supraventricular tachycardia, conduction disease, and cardiomyopathy.","method":"In vitro kinase autophosphorylation assay of mutant vs. wild-type TNNI3K","journal":"Heart rhythm","confidence":"Medium","confidence_rationale":"Tier 2 — autophosphorylation assay corroborated by genetic co-segregation in 3 independent families","pmids":["30010057"],"is_preprint":false},{"year":2019,"finding":"Tnni3k kinase activity controls the frequency of mononuclear diploid cardiomyocytes; a kinase-dead knock-in allele (K489R) phenocopies Tnni3k null effects; common human TNNI3K kinase domain variants substantially reduce kinase activity; Tnni3k function converges with oxidative stress to regulate mononuclear diploid cardiomyocyte frequency.","method":"Kinase-dead knock-in mouse model, in vitro kinase assay of human variant proteins, mononuclear diploid cardiomyocyte quantification, null allele NMD analysis","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro kinase assay + kinase-dead mouse model + multiple alleles tested, replicated across species","pmids":["31589606"],"is_preprint":false},{"year":2021,"finding":"Loss of TNNI3K kinase activity (null, kinase-dead K489R, or hypomorphic I686T allele) causes concentric ventricular remodeling, reduced cardiomyocyte aspect ratio, impaired cardiomyocyte contractility and calcium dynamics, and diminished PKA signaling in response to isoproterenol, demonstrating a beneficial role of TNNI3K kinase activity in the adult heart.","method":"Tnni3k null, kinase-dead, and hypomorphic knock-in mouse models; cardiomyocyte morphometry; calcium imaging; contractility assays; PKA signaling assay (isoproterenol response); echocardiography","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 1-2 — multiple alleles with orthogonal cellular and in vivo readouts, single study","pmids":["33084860"],"is_preprint":false},{"year":2023,"finding":"Two novel TNNI3K missense variants (p.Ile512Thr and p.His592Tyr) associated with DCM, CCD, and SVT show increased autophosphorylation, while a likely benign variant (p.Arg556_Asn590del) shows depleted autophosphorylation, supporting enhanced autophosphorylation as the pathogenic mechanism.","method":"TNNI3K autophosphorylation assay, genetic co-segregation, burden testing in UK Biobank","journal":"Circulation. Genomic and precision medicine","confidence":"Medium","confidence_rationale":"Tier 2 — autophosphorylation assay with genetic segregation, single lab","pmids":["37199186"],"is_preprint":false},{"year":2023,"finding":"Tnni3k influences both S-phase re-entry and completion of cell division in cardiomyocytes after cardiac injury, as determined by retrospective analysis of cardiomyocyte proliferation using single-cell ventricular suspensions.","method":"Retrospective cell cycle analysis of single-cell ventricular suspensions, Tnni3k knockout mice","journal":"Journal of molecular and cellular cardiology","confidence":"Medium","confidence_rationale":"Tier 2 — loss-of-function with specific cellular phenotype readout, single lab","pmids":["37597489"],"is_preprint":false},{"year":2024,"finding":"Two TNNI3K missense variants (p.Leu577Phe and p.Pro742Leu) associated with congenital junctional ectopic tachycardia show substantially reduced kinase activity, indicating that loss-of-function of TNNI3K kinase activity underlies this arrhythmia.","method":"TNNI3K kinase activity assay, genetic co-segregation analysis","journal":"Clinical genetics","confidence":"Medium","confidence_rationale":"Tier 2 — kinase activity assay with genetic segregation, single lab","pmids":["38424693"],"is_preprint":false},{"year":2026,"finding":"Tnni3k kinase activity is cardioprotective in viral myocarditis: Tnni3k knockout and kinase-dead mice show greater cardiac macrophage infiltration and inflammation following CVB3 infection compared to wild-type controls, demonstrating a kinase-activity-dependent anti-inflammatory role.","method":"Tnni3k knockout and kinase-dead knock-in mouse models, CVB3 inoculation, histological quantification of cardiac inflammation and macrophage infiltration","journal":"Journal of cardiovascular development and disease","confidence":"Medium","confidence_rationale":"Tier 2 — two independent loss-of-function alleles with specific 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, autophosphorylates via its ANK domain (negatively regulated by its C-terminal domain and by AOP-1 binding), phosphorylates cardiac troponin I at Ser43 and Thr143 to modulate myofilament contractility, drives p38 MAPK-dependent mitochondrial oxidative stress during ischemia/reperfusion injury, controls atrioventricular conduction, and regulates mononuclear diploid cardiomyocyte frequency and proliferative capacity—with its kinase activity being required for all these functions as demonstrated by kinase-dead alleles in mice."},"narrative":{"teleology":[{"year":2007,"claim":"Establishing that TNNI3K is a dual-specificity kinase whose activity depends on ANK-domain-mediated autophosphorylation and dimerization, with negative regulation by its C-terminal domain and the interactor AOP-1, resolved the basic enzymatic mechanism and regulatory logic of this previously uncharacterized cardiac kinase.","evidence":"In vitro kinase assays with domain deletions/mutations; yeast two-hybrid, co-IP, and kinase inhibition assays with AOP-1","pmids":["17660584","18205602"],"confidence":"Medium","gaps":["No in vivo validation of domain-deletion effects","AOP-1 inhibitory mechanism not structurally resolved","Substrate specificity in vivo unknown"]},{"year":2007,"claim":"Identifying MEF2C as an essential transcriptional activator of the TNNI3K promoter explained the gene's cardiomyocyte-restricted expression pattern.","evidence":"Promoter truncation, EMSA supershift, and MEF2C antisense knockdown in cardiac cell lines","pmids":["18021318"],"confidence":"Medium","gaps":["No chromatin-level in vivo validation (ChIP)","Other transcription factors that cooperate with MEF2C not identified"]},{"year":2008,"claim":"Demonstrating that TNNI3K overexpression promotes cardiomyocyte differentiation, enhances contractile function, and suppresses p38/JNK-mediated apoptosis established a pro-survival and pro-contractile role in the cardiac context.","evidence":"P19CL6 differentiation assay, intramyocardial transplantation in MI mouse model, apoptosis signaling readouts","pmids":["18552163"],"confidence":"Medium","gaps":["Overexpression-only design; no loss-of-function control","Signaling intermediates between TNNI3K and p38/JNK not defined"]},{"year":2009,"claim":"Showing that TNNI3K transgenic overexpression worsens disease progression in both calsequestrin-transgenic and pressure-overload heart failure models revealed that excessive TNNI3K activity is deleterious during cardiac stress.","evidence":"Double-transgenic (TNNI3K/Csq) and pressure-overload mouse models with echocardiography and survival analysis","pmids":["19763165"],"confidence":"High","gaps":["Downstream effectors not identified","Dose–response relationship between expression level and pathology not defined"]},{"year":2012,"claim":"Linking TNNI3K expression level to PR interval duration and confirming this via transgenic overexpression established TNNI3K as a modulator of atrioventricular conduction, connecting kinase function to cardiac electrophysiology.","evidence":"eQTL mapping, mRNA–PR interval correlation, transgenic overexpression with ECG in DBA/2J mice","pmids":["23236294"],"confidence":"High","gaps":["Cellular mechanism of conduction modulation (ion channel targets) not identified","Not tested in human conduction disease at this time"]},{"year":2012,"claim":"Demonstrating that kinase-dead TNNI3K fails to drive cardiac remodeling in pressure overload and localizing the protein to the Z disc proved that kinase catalytic activity—not scaffolding—is the disease-relevant function and placed TNNI3K at the sarcomere.","evidence":"Wild-type vs. kinase-dead TNNI3K transgenic mice under pressure overload; immunostaining; in vitro kinase assay and proteomics","pmids":["23085512"],"confidence":"High","gaps":["Direct phosphorylation substrates at the Z disc beyond cTnI not identified"]},{"year":2013,"claim":"Identifying cardiac troponin I as a direct TNNI3K substrate phosphorylated at Ser43/Thr143 (and Ser22/Ser23 in a parallel study), with functional effects on cardiomyocyte contraction, provided the first defined substrate–function link for this kinase.","evidence":"Co-IP, in vitro kinase assay with site-specific antibodies, overexpression/knockdown in adult rat ventricular myocytes, contraction measurements; parallel transgenic mouse study with phosphoamino acid analysis","pmids":["23369981","23472207"],"confidence":"Medium","gaps":["Discrepancy between studies on exact cTnI phosphorylation sites (Ser43/Thr143 vs. Ser22/Ser23) not reconciled","Structural basis of TNNI3K–cTnI interaction unknown"]},{"year":2013,"claim":"Establishing that TNNI3K drives ischemia/reperfusion injury through p38 MAPK activation and mitochondrial superoxide production—reversible by pharmacologic TNNI3K inhibition—defined a druggable pathogenic pathway and validated TNNI3K as a therapeutic target.","evidence":"Mouse I/R model, mitochondrial superoxide and p38 phosphorylation measurements, small-molecule TNNI3K inhibitors reducing infarct size","pmids":["24132636"],"confidence":"High","gaps":["Direct substrate linking TNNI3K to p38 activation not identified","Long-term in vivo efficacy and selectivity of inhibitors not tested"]},{"year":2015,"claim":"Solving the crystal structure of TNNI3K in complex with a purine-based inhibitor revealed the kinase active-site architecture and enabled rational inhibitor design.","evidence":"X-ray crystallography of TNNI3K–inhibitor complex","pmids":["26355916"],"confidence":"High","gaps":["No structure of full-length TNNI3K or of the ANK domain","No substrate-bound co-crystal structure"]},{"year":2018,"claim":"Demonstrating that the TNNI3K p.Glu768Lys variant has enhanced autophosphorylation and co-segregates with familial supraventricular tachycardia, conduction disease, and cardiomyopathy in three families established gain-of-function as a human disease mechanism.","evidence":"In vitro autophosphorylation assay of mutant vs. wild-type; genetic co-segregation in three independent families","pmids":["30010057"],"confidence":"Medium","gaps":["No in vivo knock-in model of this variant","Mechanism by which enhanced autophosphorylation leads to arrhythmia not defined"]},{"year":2019,"claim":"Showing that kinase-dead knock-in (K489R) phenocopies the Tnni3k null in controlling mononuclear diploid cardiomyocyte frequency—and that common human variants reduce kinase activity—linked TNNI3K kinase activity to cardiomyocyte ploidy and regenerative potential.","evidence":"Kinase-dead knock-in and null mice; in vitro kinase assay of human variant proteins; mononuclear diploid cardiomyocyte quantification","pmids":["31589606"],"confidence":"High","gaps":["Mechanism by which kinase activity controls cytokinesis completion unknown","Downstream phosphorylation targets in ploidy regulation not identified"]},{"year":2021,"claim":"Demonstrating that loss of TNNI3K kinase activity (null, kinase-dead, hypomorphic alleles) causes concentric remodeling, impaired calcium dynamics, and diminished PKA signaling revealed an essential homeostatic role in the adult heart.","evidence":"Three independent Tnni3k alleles with cardiomyocyte morphometry, calcium imaging, contractility, PKA signaling, and echocardiography","pmids":["33084860"],"confidence":"High","gaps":["Direct mechanism linking TNNI3K to PKA pathway not resolved","Whether remodeling is cell-autonomous not confirmed"]},{"year":2023,"claim":"Further pathogenic TNNI3K variants with enhanced autophosphorylation reinforced gain-of-function as the dominant disease mechanism for DCM/CCD/SVT, while Tnni3k was shown to influence both S-phase re-entry and cytokinesis completion after injury, extending its role in cardiomyocyte proliferation.","evidence":"Autophosphorylation assays with genetic segregation and UK Biobank burden testing; single-cell ventricular cell-cycle analysis in Tnni3k knockout mice after injury","pmids":["37199186","37597489"],"confidence":"Medium","gaps":["No rescue experiments confirming variant causality","Cell-cycle targets of TNNI3K not identified"]},{"year":2024,"claim":"Identifying loss-of-function TNNI3K variants underlying congenital junctional ectopic tachycardia revealed that both gain- and loss-of-function of kinase activity cause distinct arrhythmia phenotypes, establishing TNNI3K as a bidirectional regulator of cardiac rhythm.","evidence":"Kinase activity assay of p.Leu577Phe and p.Pro742Leu variants with genetic co-segregation","pmids":["38424693"],"confidence":"Medium","gaps":["Mechanism by which reduced kinase activity produces junctional ectopic tachycardia not defined","No animal model of these specific variants"]},{"year":2026,"claim":"Demonstrating that Tnni3k knockout and kinase-dead mice exhibit increased cardiac macrophage infiltration during viral myocarditis extended the kinase-dependent functions of TNNI3K to anti-inflammatory cardioprotection.","evidence":"Tnni3k knockout and kinase-dead mice infected with CVB3; histological quantification of macrophage infiltration","pmids":["41745317"],"confidence":"Medium","gaps":["Signaling pathway from TNNI3K to macrophage recruitment not defined","Whether effect is cardiomyocyte-autonomous or involves paracrine signaling unknown"]},{"year":null,"claim":"Major open questions include the full phosphoproteome of TNNI3K substrates beyond cTnI, the structural basis of full-length TNNI3K regulation (including ANK domain and dimerization), the direct signaling intermediates linking TNNI3K to p38 MAPK and PKA pathways, and how kinase activity controls cardiomyocyte cytokinesis and ploidy.","evidence":"","pmids":[],"confidence":"Low","gaps":["No unbiased phosphoproteomics screen for TNNI3K substrates published","No full-length TNNI3K crystal structure","Mechanism connecting TNNI3K kinase activity to cardiomyocyte cell division unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,6,7,8,13]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,6,7,8,11,13]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[6]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[3,9,14]},{"term_id":"R-HSA-397014","term_label":"Muscle contraction","supporting_discovery_ids":[6,7,8]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[4,9,10,12,15,17]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[3,9]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[13,16]}],"complexes":[],"partners":["TNNI3","AOP-1","MEF2C"],"other_free_text":[]},"mechanistic_narrative":"TNNI3K is a cardiomyocyte-specific dual-specificity (Tyr and Ser/Thr) kinase that localizes to the sarcomere Z disc and functions as a central regulator of cardiac conduction, myofilament contractility, cardiomyocyte ploidy, and the cardiac stress response [PMID:23085512, PMID:31589606, PMID:23236294]. It phosphorylates cardiac troponin I at Ser43 and Thr143 to enhance cardiomyocyte contraction, and its kinase activity—dependent on N-terminal ANK domain-mediated autophosphorylation and negatively regulated by the C-terminal domain and the interactor AOP-1—drives p38 MAPK-dependent mitochondrial oxidative stress during ischemia/reperfusion injury and controls mononuclear diploid cardiomyocyte frequency and proliferative capacity [PMID:23369981, PMID:17660584, PMID:18205602, PMID:24132636, PMID:31589606, PMID:37597489]. Gain-of-function TNNI3K missense variants with enhanced autophosphorylation cause familial dilated cardiomyopathy, cardiac conduction disease, and supraventricular tachycardia, whereas loss-of-function variants underlie congenital junctional ectopic tachycardia [PMID:30010057, PMID:37199186, PMID:38424693]. Loss of TNNI3K kinase activity also produces concentric ventricular remodeling with impaired calcium dynamics, diminished PKA signaling, and increased cardiac inflammation during viral myocarditis [PMID:33084860, PMID:41745317]."},"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":47,"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":"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\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (Y2H, pulldown, co-IP, kinase assay), single lab\",\n      \"pmids\": [\"18205602\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"MEF2C is an essential transcriptional regulator of TNNI3K/CARK expression; MEF2 binding sites in the minimal 151 bp promoter are the most critical cis-acting elements, confirmed by mutational analysis, EMSA supershift, and MEF2C antisense knockdown.\",\n      \"method\": \"Promoter truncation analysis, mutational analysis, EMSA (supershift), MEF2C antisense knockdown, co-transfection\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (EMSA, mutagenesis, antisense KD), single lab\",\n      \"pmids\": [\"18021318\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"TNNI3K promotes cardiomyocyte differentiation from P19CL6 cells, enhances cardiac contractile function, and suppresses p38/JNK-mediated apoptosis, as shown by overexpression experiments and intramyocardial transplantation in myocardial infarction mice.\",\n      \"method\": \"Cell differentiation assay, overexpression in P19CL6 cells, intramyocardial transplantation in MI mouse model, measurement of beating frequency/contractile force, apoptosis assays (annexin-V, Bax, p38/JNK phosphorylation)\",\n      \"journal\": \"American journal of physiology. Heart and circulatory physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple functional readouts in vitro and in vivo, single lab\",\n      \"pmids\": [\"18552163\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"TNNI3K expression modifies cardiac disease progression: transgenic overexpression of TNNI3K combined with Calsequestrin transgene severely impairs systolic function and reduces survival; TNNI3K also accelerates disease in pressure-overload heart failure model.\",\n      \"method\": \"Transgenic mouse models (TNNI3K/Csq double transgenic, pressure-overload), echocardiography, survival analysis\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple in vivo genetic models with functional cardiac readouts, replicated across disease models\",\n      \"pmids\": [\"19763165\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Tnni3k expression level positively correlates with PR interval duration; overexpression of hTNNI3K in DBA/2J mice prolongs PR interval, identifying TNNI3K as a modulator of atrioventricular conduction.\",\n      \"method\": \"Expression QTL mapping, mRNA-PR interval correlation, transgenic overexpression, ECG measurement\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — eQTL mapping plus transgenic functional validation, replicated in congenic mice\",\n      \"pmids\": [\"23236294\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"TNNI3K is a dual Tyr and Ser/Thr kinase; its kinase activity drives cardiac remodeling including reduced sarcomere length and altered titin isoform composition; kinase-dead TNNI3K does not promote disease progression in pressure-overload model; TNNI3K protein localizes to the sarcomere Z disc.\",\n      \"method\": \"In vitro kinase assay, proteomics, transgenic mice (wild-type vs. kinase-dead TNNI3K), pressure-overload model, immunostaining with anti-TNNI3K antisera\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro kinase assay + kinase-dead transgenic mice + localization, multiple orthogonal methods\",\n      \"pmids\": [\"23085512\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"TNNI3K interacts with cardiac troponin I (cTnI) and phosphorylates cTnI at Ser43 and Thr143 (but not Ser23/24 or Ser44) in vitro; overexpression of rTNNI3K in adult rat cardiomyocytes increases cTnI phosphorylation at these sites and enhances cardiomyocyte contraction, while knockdown reduces both.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay with site-specific antibodies, overexpression/knockdown in adult rat ventricular myocytes, cardiomyocyte contraction measurement\",\n      \"journal\": \"Brazilian journal of medical and biological research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro kinase assay + co-IP + cellular overexpression/KD, single lab\",\n      \"pmids\": [\"23369981\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"TNNI3K overexpression in transgenic mice promotes physiological concentric cardiac hypertrophy with enhanced function; yeast two-hybrid and co-immunoprecipitation identified cTnI as a TNNI3K target; TNNI3K induces cTnI phosphorylation at Ser22/Ser23 in vivo and in vitro; phosphoamino acid analysis confirms TNNI3K is a protein-tyrosine kinase.\",\n      \"method\": \"Transgenic mouse model, echocardiography, yeast two-hybrid, co-immunoprecipitation, in vitro kinase assay, phosphoamino acid analysis\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods including in vivo, Y2H, co-IP, and in vitro kinase assay\",\n      \"pmids\": [\"23472207\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"TNNI3K promotes ischemia/reperfusion injury through increased mitochondrial superoxide production and impaired mitochondrial function, acting largely via p38 MAPK activation; pharmacologic TNNI3K inhibition reduces mitochondrial superoxide, p38 activation, and infarct size.\",\n      \"method\": \"Mouse I/R injury model, mitochondrial superoxide measurement, p38 MAPK phosphorylation assays, small-molecule TNNI3K inhibitors, cardiac function assessment\",\n      \"journal\": \"Science translational medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal in vivo and mechanistic readouts, inhibitor pharmacology corroborating genetic findings\",\n      \"pmids\": [\"24132636\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"A TNNI3K G526D missense mutation in the kinase domain causes abnormal peptide aggregation in vitro; in silico docking models predict altered dimerization; ventricular tissue from carriers shows reduced TNNI3K protein with amorphous nuclear and sarcoplasmic inclusions, indicating dominant-negative loss of function.\",\n      \"method\": \"In vitro peptide aggregation assay, in silico molecular docking, immunohistochemistry of human ventricular tissue\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — in vitro aggregation plus patient tissue histopathology, single study\",\n      \"pmids\": [\"24925317\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"X-ray crystal structure of TNNI3K bound to a purine-based inhibitor confirmed Type I binding mode and elucidated the kinase active site architecture, enabling structure-activity relationship analysis and design of potent selective inhibitors.\",\n      \"method\": \"X-ray crystallography of TNNI3K-inhibitor complex\",\n      \"journal\": \"Journal of medicinal chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure directly resolving active site\",\n      \"pmids\": [\"26355916\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The TNNI3K p.Glu768Lys variant displays enhanced kinase autophosphorylation activity, consistent with a gain-of-function mechanism underlying familial supraventricular tachycardia, conduction disease, and cardiomyopathy.\",\n      \"method\": \"In vitro kinase autophosphorylation assay of mutant vs. wild-type TNNI3K\",\n      \"journal\": \"Heart rhythm\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — autophosphorylation assay corroborated by genetic co-segregation in 3 independent families\",\n      \"pmids\": [\"30010057\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Tnni3k kinase activity controls the frequency of mononuclear diploid cardiomyocytes; a kinase-dead knock-in allele (K489R) phenocopies Tnni3k null effects; common human TNNI3K kinase domain variants substantially reduce kinase activity; Tnni3k function converges with oxidative stress to regulate mononuclear diploid cardiomyocyte frequency.\",\n      \"method\": \"Kinase-dead knock-in mouse model, in vitro kinase assay of human variant proteins, mononuclear diploid cardiomyocyte quantification, null allele NMD analysis\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro kinase assay + kinase-dead mouse model + multiple alleles tested, replicated across species\",\n      \"pmids\": [\"31589606\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Loss of TNNI3K kinase activity (null, kinase-dead K489R, or hypomorphic I686T allele) causes concentric ventricular remodeling, reduced cardiomyocyte aspect ratio, impaired cardiomyocyte contractility and calcium dynamics, and diminished PKA signaling in response to isoproterenol, demonstrating a beneficial role of TNNI3K kinase activity in the adult heart.\",\n      \"method\": \"Tnni3k null, kinase-dead, and hypomorphic knock-in mouse models; cardiomyocyte morphometry; calcium imaging; contractility assays; PKA signaling assay (isoproterenol response); echocardiography\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple alleles with orthogonal cellular and in vivo readouts, single study\",\n      \"pmids\": [\"33084860\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Two novel TNNI3K missense variants (p.Ile512Thr and p.His592Tyr) associated with DCM, CCD, and SVT show increased autophosphorylation, while a likely benign variant (p.Arg556_Asn590del) shows depleted autophosphorylation, supporting enhanced autophosphorylation as the pathogenic mechanism.\",\n      \"method\": \"TNNI3K autophosphorylation assay, genetic co-segregation, burden testing in UK Biobank\",\n      \"journal\": \"Circulation. Genomic and precision medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — autophosphorylation assay with genetic segregation, single lab\",\n      \"pmids\": [\"37199186\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Tnni3k influences both S-phase re-entry and completion of cell division in cardiomyocytes after cardiac injury, as determined by retrospective analysis of cardiomyocyte proliferation using single-cell ventricular suspensions.\",\n      \"method\": \"Retrospective cell cycle analysis of single-cell ventricular suspensions, Tnni3k knockout mice\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — loss-of-function with specific cellular phenotype readout, single lab\",\n      \"pmids\": [\"37597489\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Two TNNI3K missense variants (p.Leu577Phe and p.Pro742Leu) associated with congenital junctional ectopic tachycardia show substantially reduced kinase activity, indicating that loss-of-function of TNNI3K kinase activity underlies this arrhythmia.\",\n      \"method\": \"TNNI3K kinase activity assay, genetic co-segregation analysis\",\n      \"journal\": \"Clinical genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — kinase activity assay with genetic segregation, single lab\",\n      \"pmids\": [\"38424693\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Tnni3k kinase activity is cardioprotective in viral myocarditis: Tnni3k knockout and kinase-dead mice show greater cardiac macrophage infiltration and inflammation following CVB3 infection compared to wild-type controls, demonstrating a kinase-activity-dependent anti-inflammatory role.\",\n      \"method\": \"Tnni3k knockout and kinase-dead knock-in mouse models, CVB3 inoculation, histological quantification of cardiac inflammation and macrophage infiltration\",\n      \"journal\": \"Journal of cardiovascular development and disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — two independent loss-of-function alleles with specific 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, autophosphorylates via its ANK domain (negatively regulated by its C-terminal domain and by AOP-1 binding), phosphorylates cardiac troponin I at Ser43 and Thr143 to modulate myofilament contractility, drives p38 MAPK-dependent mitochondrial oxidative stress during ischemia/reperfusion injury, controls atrioventricular conduction, and regulates mononuclear diploid cardiomyocyte frequency and proliferative capacity—with its kinase activity being required for all these functions as demonstrated by kinase-dead alleles in mice.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"TNNI3K is a cardiomyocyte-specific dual-specificity (Tyr and Ser/Thr) kinase that localizes to the sarcomere Z disc and functions as a central regulator of cardiac conduction, myofilament contractility, cardiomyocyte ploidy, and the cardiac stress response [PMID:23085512, PMID:31589606, PMID:23236294]. It phosphorylates cardiac troponin I at Ser43 and Thr143 to enhance cardiomyocyte contraction, and its kinase activity—dependent on N-terminal ANK domain-mediated autophosphorylation and negatively regulated by the C-terminal domain and the interactor AOP-1—drives p38 MAPK-dependent mitochondrial oxidative stress during ischemia/reperfusion injury and controls mononuclear diploid cardiomyocyte frequency and proliferative capacity [PMID:23369981, PMID:17660584, PMID:18205602, PMID:24132636, PMID:31589606, PMID:37597489]. Gain-of-function TNNI3K missense variants with enhanced autophosphorylation cause familial dilated cardiomyopathy, cardiac conduction disease, and supraventricular tachycardia, whereas loss-of-function variants underlie congenital junctional ectopic tachycardia [PMID:30010057, PMID:37199186, PMID:38424693]. Loss of TNNI3K kinase activity also produces concentric ventricular remodeling with impaired calcium dynamics, diminished PKA signaling, and increased cardiac inflammation during viral myocarditis [PMID:33084860, PMID:41745317].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Establishing that TNNI3K is a dual-specificity kinase whose activity depends on ANK-domain-mediated autophosphorylation and dimerization, with negative regulation by its C-terminal domain and the interactor AOP-1, resolved the basic enzymatic mechanism and regulatory logic of this previously uncharacterized cardiac kinase.\",\n      \"evidence\": \"In vitro kinase assays with domain deletions/mutations; yeast two-hybrid, co-IP, and kinase inhibition assays with AOP-1\",\n      \"pmids\": [\"17660584\", \"18205602\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No in vivo validation of domain-deletion effects\", \"AOP-1 inhibitory mechanism not structurally resolved\", \"Substrate specificity in vivo unknown\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Identifying MEF2C as an essential transcriptional activator of the TNNI3K promoter explained the gene's cardiomyocyte-restricted expression pattern.\",\n      \"evidence\": \"Promoter truncation, EMSA supershift, and MEF2C antisense knockdown in cardiac cell lines\",\n      \"pmids\": [\"18021318\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No chromatin-level in vivo validation (ChIP)\", \"Other transcription factors that cooperate with MEF2C not identified\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Demonstrating that TNNI3K overexpression promotes cardiomyocyte differentiation, enhances contractile function, and suppresses p38/JNK-mediated apoptosis established a pro-survival and pro-contractile role in the cardiac context.\",\n      \"evidence\": \"P19CL6 differentiation assay, intramyocardial transplantation in MI mouse model, apoptosis signaling readouts\",\n      \"pmids\": [\"18552163\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Overexpression-only design; no loss-of-function control\", \"Signaling intermediates between TNNI3K and p38/JNK not defined\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Showing that TNNI3K transgenic overexpression worsens disease progression in both calsequestrin-transgenic and pressure-overload heart failure models revealed that excessive TNNI3K activity is deleterious during cardiac stress.\",\n      \"evidence\": \"Double-transgenic (TNNI3K/Csq) and pressure-overload mouse models with echocardiography and survival analysis\",\n      \"pmids\": [\"19763165\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream effectors not identified\", \"Dose–response relationship between expression level and pathology not defined\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Linking TNNI3K expression level to PR interval duration and confirming this via transgenic overexpression established TNNI3K as a modulator of atrioventricular conduction, connecting kinase function to cardiac electrophysiology.\",\n      \"evidence\": \"eQTL mapping, mRNA–PR interval correlation, transgenic overexpression with ECG in DBA/2J mice\",\n      \"pmids\": [\"23236294\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cellular mechanism of conduction modulation (ion channel targets) not identified\", \"Not tested in human conduction disease at this time\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Demonstrating that kinase-dead TNNI3K fails to drive cardiac remodeling in pressure overload and localizing the protein to the Z disc proved that kinase catalytic activity—not scaffolding—is the disease-relevant function and placed TNNI3K at the sarcomere.\",\n      \"evidence\": \"Wild-type vs. kinase-dead TNNI3K transgenic mice under pressure overload; immunostaining; in vitro kinase assay and proteomics\",\n      \"pmids\": [\"23085512\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct phosphorylation substrates at the Z disc beyond cTnI not identified\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identifying cardiac troponin I as a direct TNNI3K substrate phosphorylated at Ser43/Thr143 (and Ser22/Ser23 in a parallel study), with functional effects on cardiomyocyte contraction, provided the first defined substrate–function link for this kinase.\",\n      \"evidence\": \"Co-IP, in vitro kinase assay with site-specific antibodies, overexpression/knockdown in adult rat ventricular myocytes, contraction measurements; parallel transgenic mouse study with phosphoamino acid analysis\",\n      \"pmids\": [\"23369981\", \"23472207\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Discrepancy between studies on exact cTnI phosphorylation sites (Ser43/Thr143 vs. Ser22/Ser23) not reconciled\", \"Structural basis of TNNI3K–cTnI interaction unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Establishing that TNNI3K drives ischemia/reperfusion injury through p38 MAPK activation and mitochondrial superoxide production—reversible by pharmacologic TNNI3K inhibition—defined a druggable pathogenic pathway and validated TNNI3K as a therapeutic target.\",\n      \"evidence\": \"Mouse I/R model, mitochondrial superoxide and p38 phosphorylation measurements, small-molecule TNNI3K inhibitors reducing infarct size\",\n      \"pmids\": [\"24132636\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct substrate linking TNNI3K to p38 activation not identified\", \"Long-term in vivo efficacy and selectivity of inhibitors not tested\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Solving the crystal structure of TNNI3K in complex with a purine-based inhibitor revealed the kinase active-site architecture and enabled rational inhibitor design.\",\n      \"evidence\": \"X-ray crystallography of TNNI3K–inhibitor complex\",\n      \"pmids\": [\"26355916\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structure of full-length TNNI3K or of the ANK domain\", \"No substrate-bound co-crystal structure\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Demonstrating that the TNNI3K p.Glu768Lys variant has enhanced autophosphorylation and co-segregates with familial supraventricular tachycardia, conduction disease, and cardiomyopathy in three families established gain-of-function as a human disease mechanism.\",\n      \"evidence\": \"In vitro autophosphorylation assay of mutant vs. wild-type; genetic co-segregation in three independent families\",\n      \"pmids\": [\"30010057\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No in vivo knock-in model of this variant\", \"Mechanism by which enhanced autophosphorylation leads to arrhythmia not defined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showing that kinase-dead knock-in (K489R) phenocopies the Tnni3k null in controlling mononuclear diploid cardiomyocyte frequency—and that common human variants reduce kinase activity—linked TNNI3K kinase activity to cardiomyocyte ploidy and regenerative potential.\",\n      \"evidence\": \"Kinase-dead knock-in and null mice; in vitro kinase assay of human variant proteins; mononuclear diploid cardiomyocyte quantification\",\n      \"pmids\": [\"31589606\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which kinase activity controls cytokinesis completion unknown\", \"Downstream phosphorylation targets in ploidy regulation not identified\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrating that loss of TNNI3K kinase activity (null, kinase-dead, hypomorphic alleles) causes concentric remodeling, impaired calcium dynamics, and diminished PKA signaling revealed an essential homeostatic role in the adult heart.\",\n      \"evidence\": \"Three independent Tnni3k alleles with cardiomyocyte morphometry, calcium imaging, contractility, PKA signaling, and echocardiography\",\n      \"pmids\": [\"33084860\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct mechanism linking TNNI3K to PKA pathway not resolved\", \"Whether remodeling is cell-autonomous not confirmed\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Further pathogenic TNNI3K variants with enhanced autophosphorylation reinforced gain-of-function as the dominant disease mechanism for DCM/CCD/SVT, while Tnni3k was shown to influence both S-phase re-entry and cytokinesis completion after injury, extending its role in cardiomyocyte proliferation.\",\n      \"evidence\": \"Autophosphorylation assays with genetic segregation and UK Biobank burden testing; single-cell ventricular cell-cycle analysis in Tnni3k knockout mice after injury\",\n      \"pmids\": [\"37199186\", \"37597489\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No rescue experiments confirming variant causality\", \"Cell-cycle targets of TNNI3K not identified\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identifying loss-of-function TNNI3K variants underlying congenital junctional ectopic tachycardia revealed that both gain- and loss-of-function of kinase activity cause distinct arrhythmia phenotypes, establishing TNNI3K as a bidirectional regulator of cardiac rhythm.\",\n      \"evidence\": \"Kinase activity assay of p.Leu577Phe and p.Pro742Leu variants with genetic co-segregation\",\n      \"pmids\": [\"38424693\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which reduced kinase activity produces junctional ectopic tachycardia not defined\", \"No animal model of these specific variants\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Demonstrating that Tnni3k knockout and kinase-dead mice exhibit increased cardiac macrophage infiltration during viral myocarditis extended the kinase-dependent functions of TNNI3K to anti-inflammatory cardioprotection.\",\n      \"evidence\": \"Tnni3k knockout and kinase-dead mice infected with CVB3; histological quantification of macrophage infiltration\",\n      \"pmids\": [\"41745317\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Signaling pathway from TNNI3K to macrophage recruitment not defined\", \"Whether effect is cardiomyocyte-autonomous or involves paracrine signaling unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Major open questions include the full phosphoproteome of TNNI3K substrates beyond cTnI, the structural basis of full-length TNNI3K regulation (including ANK domain and dimerization), the direct signaling intermediates linking TNNI3K to p38 MAPK and PKA pathways, and how kinase activity controls cardiomyocyte cytokinesis and ploidy.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No unbiased phosphoproteomics screen for TNNI3K substrates published\", \"No full-length TNNI3K crystal structure\", \"Mechanism connecting TNNI3K kinase activity to cardiomyocyte cell division unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 6, 7, 8, 13]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 6, 7, 8, 11, 13]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [3, 9, 14]},\n      {\"term_id\": \"R-HSA-397014\", \"supporting_discovery_ids\": [6, 7, 8]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [4, 9, 10, 12, 15, 17]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [3, 9]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [13, 16]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"TNNI3\",\n      \"AOP-1\",\n      \"MEF2C\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}