{"gene":"MYL2","run_date":"2026-06-10T05:19:52","timeline":{"discoveries":[{"year":2015,"finding":"MYL2 (MLC-2v) phosphorylation at Ser15 by myosin light chain kinase displays a specific spatial pattern (high in epicardium, low in endocardium) and directly regulates cross-bridge cycling kinetics and calcium-dependent cardiac muscle contraction, as established by genetic mouse models and computational studies.","method":"Genetic mouse models, computational modeling, phosphorylation assays","journal":"Gene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple genetic mouse models and orthogonal methods (echocardiography, contractile mechanics, phosphorylation assays) reviewed from multiple labs, but this is a review paper summarizing prior work rather than a single primary study","pmids":["26074085"],"is_preprint":false},{"year":2013,"finding":"MYL2 encodes the myosin regulatory light chain (MLC-2V) that binds to the flexible neck region of the myosin heavy chain in the hexameric myosin complex; recessive loss-of-function mutations disrupting the second EF-hand domain of MYL2 cause cardioskeletal myopathy, establishing a structural/regulatory role in muscle contraction.","method":"Linkage analysis, exome sequencing, immunohistochemistry, splice site mutation characterization","journal":"Brain","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic mapping plus immunohistochemical verification of absent/abnormal protein in patient muscle; single study but orthogonal methods","pmids":["23365102"],"is_preprint":false},{"year":2015,"finding":"The DCM-associated MYL2 D94A mutation reduces α-helical content of RLC, impairs RLC binding to myosin heavy chain and incorporation into myosin, and increases actin-activated ATPase activity of reconstituted porcine cardiac myosin, without altering calcium sensitivity of force.","method":"Recombinant protein purification, in vitro reconstitution into RLC-depleted porcine cardiac preparations, circular dichroism, actin-activated ATPase assay, skinned muscle force measurements","journal":"The FEBS journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with purified proteins, mutagenesis, multiple orthogonal functional assays (ATPase, force, structural), single lab","pmids":["25825243"],"is_preprint":false},{"year":2018,"finding":"Transgenic D94A (MYL2) mice develop dilated cardiomyopathy with reduced ejection fraction and left ventricular dilation; D94A myosin motors show reduced actin-activated ATPase activity, rightward shift of force-pCa dependence, and X-ray diffraction reveals repositioning of cross-bridge mass toward thick-filament backbone, consistent with a hypocontractile state.","method":"Transgenic mouse model, echocardiography, invasive hemodynamics, small-angle X-ray diffraction, actin-activated ATPase assay, force-pCa measurements","journal":"PNAS","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vivo transgenic model combined with multiple orthogonal structural and functional assays (X-ray diffraction, ATPase, force-pCa, hemodynamics) in a single rigorous study","pmids":["29463717"],"is_preprint":false},{"year":2016,"finding":"The IVS6-1 splice-site mutation in MYL2 causes a frameshift replacing the last 32 codons; recombinant IVS6-1 RLC shows decreased binding to myosin heavy chain, reduced actin-binding in rigor, lower Vmax of actin-activated myosin ATPase, slower ATP-induced dissociation of acto-myosin complex, and reduced maximal contractile force with increased Ca2+ sensitivity in reconstituted porcine cardiac muscle preparations.","method":"Recombinant protein production, in vitro reconstitution into RLC-depleted porcine cardiac preparations, actin-activated ATPase assay, stopped-flow kinetics, skinned muscle force/pCa measurements","journal":"Frontiers in physiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — full in vitro reconstitution with multiple orthogonal assays (ATPase, stopped-flow kinetics, force-pCa, binding assays), single lab","pmids":["27378946"],"is_preprint":false},{"year":2022,"finding":"HCM-D166V mutation in MYL2 increases Ca2+ sensitivity of force and promotes premature cross-bridge movement toward thin filaments (left-shifted I11/I10-pCa by X-ray diffraction), disrupts the super-relaxed (SRX) myosin state, and promotes SRX-to-DRX transition correlating with hypercontractility; DCM-D94A favors the energy-conserving SRX state.","method":"Small-angle X-ray diffraction simultaneous with isometric force measurements on skinned papillary muscles, ATP turnover assays for SRX/DRX states, transgenic mouse models","journal":"PNAS","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — simultaneous X-ray diffraction and force measurements with SRX/DRX energetic assays, two transgenic mouse models compared, single lab but multiple orthogonal methods","pmids":["35177471"],"is_preprint":false},{"year":2019,"finding":"AAV9 delivery of phosphomimetic S15D-RLC (MYL2 Ser15Asp) into HCM-D166V transgenic mice improves cardiac output, stroke work, relaxation (reduced Tau), longitudinal strain, and contractile force in skinned papillary muscles, demonstrating that Ser15 phosphorylation of MYL2 is functionally critical for HCM-D166V cardiac dysfunction.","method":"AAV9 gene delivery in transgenic mice, echocardiography, pressure-volume loop hemodynamics, strain analysis, skinned papillary muscle force measurements","journal":"Journal of molecular medicine","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vivo gene therapy rescue with multiple functional readouts (hemodynamics, echocardiography, muscle mechanics) in a disease-relevant transgenic mouse model, single lab","pmids":["31101927"],"is_preprint":false},{"year":2019,"finding":"MYL2-R58Q iPSC-derived cardiomyocytes exhibit hypertrophy (~30% larger), myofibrillar disarray, decreased peak calcium transients, delayed calcium decay, and ~45% reduction in L-type Ca2+ channel (ICa,L) current density, establishing that this MYL2 mutation directly perturbs calcium handling in cardiomyocytes.","method":"iPSC-derived cardiomyocytes from R58Q HCM patient, calcium imaging, patch-clamp electrophysiology, immunostaining","journal":"Journal of cardiovascular translational research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — patient-specific iPSC-CM model with multiple orthogonal functional readouts (calcium imaging, electrophysiology, cell morphometry), single lab","pmids":["30796699"],"is_preprint":false},{"year":2020,"finding":"A recessive frameshift MYL2-fs variant causes active proteasomal degradation of the mutant MYL2 protein (rescuable by proteasome inhibitors), while an HCM-associated missense variant (G162R) and stop-gain variants lacking EF domains are stably expressed but show impaired subcellular localization; in a Drosophila Mlc2 knockdown model, neither MYL2-fs nor G162R supports normal cardiac function.","method":"In vitro overexpression with proteasome inhibitor rescue, immunohistochemistry on patient tissue, Drosophila in vivo rescue assay, exome sequencing","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — proteasome inhibitor rescue experiment plus in vivo Drosophila functional assay, multiple orthogonal approaches, single lab","pmids":["32453731"],"is_preprint":false},{"year":2026,"finding":"Osimertinib causes reversible cardiac dysfunction via GATA4 dephosphorylation, which suppresses MYLK3 transcription, leading to decreased MYL2 phosphorylation and sarcomere disarray; myosin activator omecamtiv prevents this cardiotoxicity.","method":"iPSC-CM in vitro model, snRNA-seq of mouse heart tissue, in vivo mouse model with transverse aortic constriction, pharmacological rescue with omecamtiv","journal":"European heart journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro and in vivo models with snRNA-seq and pharmacological rescue, single lab, multiple orthogonal approaches identifying GATA4-MYLK3-MYL2 axis","pmids":["41330421"],"is_preprint":false},{"year":2025,"finding":"Tetramethylpyrazine (TMP) directly binds to MYL2 (identified by DARTS and LC-MS/MS), increases MYL2 protein levels dose-dependently in ischemia/reperfusion-injured cells and heart tissue, and inhibits NLRP3 inflammasome activation and caspase-1-dependent pyroptosis; siRNA knockdown of MYL2 abolishes TMP's cardioprotective effects, placing MYL2 upstream of NLRP3 signaling.","method":"DARTS assay, LC-MS/MS, siRNA knockdown, NLRP3 inhibitor/agonist pharmacology, in vivo rat I/R model, in vitro H/R model","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — direct target identification by DARTS/MS plus epistatic siRNA knockdown, in vitro and in vivo models, single lab","pmids":["40754120"],"is_preprint":false},{"year":1992,"finding":"The MYL2 gene was mapped to human chromosome 12q23-q24.3 by somatic cell hybrid analysis and in situ hybridization, and was noted to regulate myosin ATPase activity.","method":"Southern blot of somatic cell hybrids, in situ hybridization to metaphase chromosomes","journal":"Genomics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal physical mapping methods establishing chromosomal localization, single lab","pmids":["1386340"],"is_preprint":false},{"year":2025,"finding":"Pathogenic HCM missense variants in MYL2 (regulatory light chain) cluster in specific molecular interfaces of the myosin interacting-heads motif (IHM) and heavy chain interfaces within the cardiac thick filament; pathogenic DCM missense variants in MYL2 alter only IHM and myosin tail interfaces; benign variants do not map to any interface, establishing that thick filament molecular interfaces are mechanistically critical for cardiomyopathy pathogenesis.","method":"Cryo-EM-based atomic model of human cardiac thick filament; mapping of >200 pathogenic and benign missense variants; clinical outcome correlation","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — cryo-EM structural mapping is high quality but this is a preprint, structural inference without direct mutagenesis validation of each MYL2 variant interface","pmids":["bio_10.1101_2025.10.03.680256"],"is_preprint":true}],"current_model":"MYL2 (ventricular myosin regulatory light chain, MLC-2v) is a ~19 kDa sarcomeric protein that binds the myosin heavy chain neck region, where its phosphorylation at Ser15 by MYLK3 (regulated by the GATA4-MYLK3-MYL2 axis) controls cross-bridge cycling kinetics, super-relaxed myosin state equilibrium, calcium sensitivity of force, and cardiac torsion; pathogenic missense mutations (e.g., D166V causing HCM hypercontractility via SRX disruption; D94A causing DCM hypocontractility via favored SRX and reduced ATPase) and recessive loss-of-function mutations (disrupting the EF-hand domain and MHC binding) each distinctly derange sarcomere mechanics and calcium handling, while MYL2 also participates upstream of NLRP3 inflammasome signaling in cardiac ischemia-reperfusion injury."},"narrative":{"mechanistic_narrative":"MYL2 encodes the ventricular myosin regulatory light chain (MLC-2v), which binds the flexible neck region of the myosin heavy chain in the hexameric sarcomeric myosin and thereby governs cross-bridge cycling kinetics, calcium-dependent contractile force, and the equilibrium between super-relaxed (SRX) and disordered-relaxed (DRX) myosin states [PMID:23365102, PMID:35177471]. Phosphorylation of MYL2 at Ser15 by myosin light chain kinase tunes cross-bridge cycling and calcium-dependent contraction, displaying a transmural gradient (high epicardium, low endocardium), and the GATA4–MYLK3–MYL2 transcriptional/phosphorylation axis sets the steady-state level of this modification [PMID:26074085, PMID:41330421]. Distinct missense substitutions derange sarcomere mechanics in opposite directions: the HCM-associated D166V mutation increases calcium sensitivity of force and shifts myosin out of the energy-conserving SRX state toward a hypercontractile DRX state, whereas the DCM-associated D94A mutation reduces RLC α-helical content and myosin incorporation, alters actin-activated ATPase, and favors the SRX state, producing a hypocontractile, dilated phenotype [PMID:25825243, PMID:29463717, PMID:35177471]. Restoring Ser15 phosphorylation via phosphomimetic S15D rescues contractile and relaxation defects in HCM-D166V hearts, demonstrating the causal role of this regulatory site [PMID:31101927]. Recessive loss-of-function and frameshift variants that disrupt the second EF-hand domain and heavy-chain binding—some triggering proteasomal degradation or mislocalization of the mutant protein—cause cardioskeletal myopathy, and pathogenic variants map preferentially to myosin interacting-heads-motif and heavy-chain interfaces of the thick filament [PMID:23365102, PMID:32453731]. Beyond the sarcomere, MYL2 acts upstream of NLRP3 inflammasome activation and caspase-1–dependent pyroptosis in cardiac ischemia–reperfusion injury [PMID:40754120].","teleology":[{"year":1992,"claim":"Establishing the chromosomal location and a basic regulatory role for MYL2 provided the genomic foothold for later disease-gene mapping.","evidence":"Somatic cell hybrid Southern blot and in situ hybridization placing MYL2 at 12q23-q24.3","pmids":["1386340"],"confidence":"Medium","gaps":["No functional mechanism beyond noting regulation of myosin ATPase","No mutation-phenotype link yet"]},{"year":2013,"claim":"Defining MYL2 as the regulatory light chain bound to the myosin neck and linking EF-hand-disrupting recessive loss-of-function to cardioskeletal myopathy fixed its structural role in muscle contraction.","evidence":"Linkage analysis, exome sequencing, and immunohistochemistry of patient muscle for a splice-site mutation","pmids":["23365102"],"confidence":"Medium","gaps":["Biochemical consequences of EF-hand disruption not reconstituted","Skeletal vs cardiac contribution not dissected"]},{"year":2015,"claim":"Reconstitution showed how a DCM mutation acts at the molecular level—weakening RLC structure, myosin incorporation, and altering ATPase—moving beyond genetic association to biochemical causation.","evidence":"Recombinant D94A RLC reconstituted into RLC-depleted porcine cardiac preparations with CD, actin-activated ATPase, and skinned-fiber force assays","pmids":["25825243"],"confidence":"High","gaps":["In vivo cardiac consequences not yet tested","Effect on SRX state not assessed in this study"]},{"year":2015,"claim":"Spatially resolved Ser15 phosphorylation by MLCK was tied to cross-bridge kinetics and calcium-dependent contraction, defining the regulatory modification of MYL2.","evidence":"Review synthesizing genetic mouse models, computational modeling, and phosphorylation assays","pmids":["26074085"],"confidence":"Medium","gaps":["Review-level synthesis rather than single primary dataset","Kinase identity and upstream control not resolved here"]},{"year":2018,"claim":"An in vivo transgenic model confirmed D94A causes dilated cardiomyopathy and linked the phenotype to reduced ATPase, rightward force-pCa shift, and structural repositioning of cross-bridges—establishing a hypocontractile mechanism.","evidence":"D94A transgenic mice with echocardiography, hemodynamics, small-angle X-ray diffraction, ATPase and force-pCa measurements","pmids":["29463717"],"confidence":"High","gaps":["SRX/DRX contribution clarified only in later work","Therapeutic reversibility not tested"]},{"year":2016,"claim":"Characterizing a frameshift splice-site variant defined how C-terminal truncation impairs myosin and actin binding, ATPase, and contractile force, broadening the loss-of-function mechanism.","evidence":"Recombinant IVS6-1 RLC reconstituted into porcine cardiac preparations with ATPase, stopped-flow kinetics, and force/pCa assays","pmids":["27378946"],"confidence":"High","gaps":["In vivo cardiac phenotype not established","Relationship to recessive myopathy variants not dissected"]},{"year":2019,"claim":"Phosphomimetic rescue demonstrated that Ser15 phosphorylation is functionally decisive, converting a regulatory observation into a therapeutic principle for MYL2-driven HCM.","evidence":"AAV9 delivery of S15D-RLC into HCM-D166V transgenic mice with hemodynamics, strain, and skinned-fiber force","pmids":["31101927"],"confidence":"High","gaps":["Durability and off-target effects of gene therapy not addressed","Applicability to other MYL2 mutations untested"]},{"year":2019,"claim":"Patient-derived iPSC-cardiomyocytes connected an HCM MYL2 mutation to disrupted calcium handling and L-type channel current, extending pathology to excitation-contraction coupling.","evidence":"R58Q iPSC-CMs with calcium imaging, patch-clamp electrophysiology, and morphometry","pmids":["30796699"],"confidence":"Medium","gaps":["Mechanistic link between RLC and ICa,L reduction unresolved","Single-cell model lacks tissue-level context"]},{"year":2020,"claim":"Variant-specific fates—proteasomal degradation of a frameshift allele versus mislocalization of stable missense/stop-gain proteins—explained how different MYL2 alleles fail, with in vivo confirmation.","evidence":"Overexpression with proteasome-inhibitor rescue, patient-tissue immunohistochemistry, and Drosophila Mlc2 knockdown rescue","pmids":["32453731"],"confidence":"Medium","gaps":["Degradation pathway components not identified","Quantitative contribution of mislocalization to human phenotype unknown"]},{"year":2022,"claim":"Simultaneous X-ray diffraction, force, and ATP-turnover assays unified HCM and DCM mechanisms around the SRX/DRX equilibrium—D166V destabilizing SRX (hypercontractility) and D94A favoring SRX (hypocontractility).","evidence":"Skinned papillary muscle X-ray diffraction with isometric force and SRX/DRX ATP turnover assays in two transgenic mouse lines","pmids":["35177471"],"confidence":"High","gaps":["How RLC mutations bias the IHM at atomic resolution not directly shown","Phosphorylation interplay with SRX not fully mapped"]},{"year":2025,"claim":"A thick-filament cryo-EM model showed pathogenic HCM and DCM variants cluster at distinct myosin interacting-heads-motif and heavy-chain interfaces while benign variants avoid them, providing a structural framework for genotype interpretation.","evidence":"Cryo-EM atomic model of human cardiac thick filament with mapping of >200 variants and clinical outcome correlation (preprint)","pmids":["bio_10.1101_2025.10.03.680256"],"confidence":"Medium","gaps":["Structural inference not validated by per-variant mutagenesis","Preprint, not peer-reviewed"]},{"year":2025,"claim":"Identifying MYL2 as a direct tetramethylpyrazine target acting upstream of NLRP3 revealed a non-sarcomeric, inflammatory-protective role in ischemia-reperfusion injury.","evidence":"DARTS/LC-MS/MS target identification, siRNA knockdown epistasis, NLRP3 pharmacology, and in vitro/in vivo I-R models","pmids":["40754120"],"confidence":"Medium","gaps":["Molecular link between MYL2 and NLRP3 not defined","Whether the effect is sarcomere-independent unclear"]},{"year":2026,"claim":"Mapping a GATA4–MYLK3–MYL2 axis explained drug-induced reversible cardiotoxicity as loss of MYL2 phosphorylation, linking transcriptional control of the kinase to sarcomere function.","evidence":"iPSC-CM model, snRNA-seq of mouse heart, transverse aortic constriction in vivo, and omecamtiv pharmacological rescue","pmids":["41330421"],"confidence":"Medium","gaps":["Direct GATA4 occupancy at MYLK3 not detailed here","Generalizability beyond osimertinib not established"]},{"year":null,"claim":"How MYL2 mechanistically couples to NLRP3 inflammasome signaling and to L-type calcium channel regulation, distinct from its sarcomeric role, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No molecular intermediary between MYL2 and NLRP3 identified","Mechanism linking RLC mutation to ICa,L reduction unknown","Phosphorylation-IHM-SRX interplay not resolved at atomic resolution"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[1,2,4]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,5,6]}],"localization":[],"pathway":[{"term_id":"R-HSA-397014","term_label":"Muscle contraction","supporting_discovery_ids":[0,1,5]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[2,3,5,8]}],"complexes":["cardiac thick filament (sarcomeric myosin hexamer)"],"partners":["MYH7","MYLK3","GATA4","NLRP3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P10916","full_name":"Myosin regulatory light chain 2, ventricular/cardiac muscle isoform","aliases":["Cardiac myosin light chain 2","Myosin light chain 2, slow skeletal/ventricular muscle isoform","MLC-2s/v","Ventricular myosin light chain 2"],"length_aa":166,"mass_kda":18.8,"function":"Contractile protein that plays a role in heart development and function (PubMed:23365102, PubMed:32453731). Following phosphorylation, plays a role in cross-bridge cycling kinetics and cardiac muscle contraction by increasing myosin lever arm stiffness and promoting myosin head diffusion; as a consequence of the increase in maximum contraction force and calcium sensitivity of contraction force. These events altogether slow down myosin kinetics and prolong duty cycle resulting in accumulated myosins being cooperatively recruited to actin binding sites to sustain thin filament activation as a means to fine-tune myofilament calcium sensitivity to force (By similarity). During cardiogenesis plays an early role in cardiac contractility by promoting cardiac myofibril assembly (By similarity)","subcellular_location":"Cytoplasm, myofibril, sarcomere, A band","url":"https://www.uniprot.org/uniprotkb/P10916/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MYL2","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MYL2","total_profiled":1310},"omim":[{"mim_id":"619424","title":"MYOPATHY, MYOFIBRILLAR, 12, INFANTILE-ONSET, WITH CARDIOMYOPATHY; MFM12","url":"https://www.omim.org/entry/619424"},{"mim_id":"618052","title":"CARDIOMYOPATHY, FAMILIAL HYPERTROPHIC, 27; CMH27","url":"https://www.omim.org/entry/618052"},{"mim_id":"613993","title":"MYOSIN, LIGHT CHAIN 7, REGULATORY; MYL7","url":"https://www.omim.org/entry/613993"},{"mim_id":"612147","title":"MYOSIN LIGHT CHAIN KINASE 3; MYLK3","url":"https://www.omim.org/entry/612147"},{"mim_id":"610762","title":"HIGH DENSITY LIPOPROTEIN CHOLESTEROL LEVEL QUANTITATIVE TRAIT LOCUS 6; HDLCQ6","url":"https://www.omim.org/entry/610762"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Microtubules","reliability":"Uncertain"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"heart muscle","ntpm":27634.5},{"tissue":"skeletal muscle","ntpm":27153.8},{"tissue":"tongue","ntpm":18492.7}],"url":"https://www.proteinatlas.org/search/MYL2"},"hgnc":{"alias_symbol":["CMH10"],"prev_symbol":[]},"alphafold":{"accession":"P10916","domains":[{"cath_id":"1.10.238.10","chopping":"15-91","consensus_level":"high","plddt":86.6335,"start":15,"end":91},{"cath_id":"1.10.238.10","chopping":"95-160","consensus_level":"high","plddt":89.7885,"start":95,"end":160}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P10916","model_url":"https://alphafold.ebi.ac.uk/files/AF-P10916-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P10916-F1-predicted_aligned_error_v6.png","plddt_mean":83.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MYL2","jax_strain_url":"https://www.jax.org/strain/search?query=MYL2"},"sequence":{"accession":"P10916","fasta_url":"https://rest.uniprot.org/uniprotkb/P10916.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P10916/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P10916"}},"corpus_meta":[{"pmid":"26074085","id":"PMC_26074085","title":"Functions of myosin light chain-2 (MYL2) in cardiac muscle and disease.","date":"2015","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/26074085","citation_count":135,"is_preprint":false},{"pmid":"9535554","id":"PMC_9535554","title":"Identification of two novel mutations in the ventricular regulatory myosin light chain gene (MYL2) associated with familial and classical forms of hypertrophic cardiomyopathy.","date":"1998","source":"Journal of molecular medicine (Berlin, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/9535554","citation_count":111,"is_preprint":false},{"pmid":"26497160","id":"PMC_26497160","title":"Hypertrophic remodelling in cardiac regulatory myosin light chain (MYL2) founder mutation carriers.","date":"2015","source":"European heart journal","url":"https://pubmed.ncbi.nlm.nih.gov/26497160","citation_count":68,"is_preprint":false},{"pmid":"23365102","id":"PMC_23365102","title":"Recessive MYL2 mutations cause infantile type I muscle fibre disease and cardiomyopathy.","date":"2013","source":"Brain : a journal of neurology","url":"https://pubmed.ncbi.nlm.nih.gov/23365102","citation_count":48,"is_preprint":false},{"pmid":"1386340","id":"PMC_1386340","title":"Localization of the gene coding for ventricular myosin regulatory light chain (MYL2) to human chromosome 12q23-q24.3.","date":"1992","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/1386340","citation_count":36,"is_preprint":false},{"pmid":"25825243","id":"PMC_25825243","title":"Novel familial dilated cardiomyopathy mutation in MYL2 affects the structure and function of myosin regulatory light chain.","date":"2015","source":"The FEBS journal","url":"https://pubmed.ncbi.nlm.nih.gov/25825243","citation_count":35,"is_preprint":false},{"pmid":"30796699","id":"PMC_30796699","title":"Induced Pluripotent Stem Cell-Derived Cardiomyocytes from a Patient with MYL2-R58Q-Mediated Apical Hypertrophic Cardiomyopathy Show Hypertrophy, Myofibrillar Disarray, and Calcium Perturbations.","date":"2019","source":"Journal of cardiovascular translational research","url":"https://pubmed.ncbi.nlm.nih.gov/30796699","citation_count":33,"is_preprint":false},{"pmid":"29463717","id":"PMC_29463717","title":"Sarcomeric perturbations of myosin motors lead to dilated cardiomyopathy in genetically modified MYL2 mice.","date":"2018","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/29463717","citation_count":31,"is_preprint":false},{"pmid":"35177471","id":"PMC_35177471","title":"Molecular basis of force-pCa relation in MYL2 cardiomyopathy mice: Role of the super-relaxed state of myosin.","date":"2022","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/35177471","citation_count":29,"is_preprint":false},{"pmid":"21259275","id":"PMC_21259275","title":"Slow cardiac myosin regulatory light chain 2 (MYL2) was down-expressed in chronic heart failure patients.","date":"2010","source":"Clinical cardiology","url":"https://pubmed.ncbi.nlm.nih.gov/21259275","citation_count":21,"is_preprint":false},{"pmid":"32453731","id":"PMC_32453731","title":"Novel frameshift variant in MYL2 reveals molecular differences between dominant and recessive forms of hypertrophic cardiomyopathy.","date":"2020","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/32453731","citation_count":20,"is_preprint":false},{"pmid":"31101927","id":"PMC_31101927","title":"Therapeutic potential of AAV9-S15D-RLC gene delivery in humanized MYL2 mouse model of HCM.","date":"2019","source":"Journal of molecular medicine (Berlin, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/31101927","citation_count":19,"is_preprint":false},{"pmid":"27378946","id":"PMC_27378946","title":"Molecular and Functional Effects of a Splice Site Mutation in the MYL2 Gene Associated with Cardioskeletal Myopathy and Early Cardiac Death in 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variants in additional neuromuscular disease genes; the dilemma of panel testing.","date":"2019","source":"Cold Spring Harbor molecular case studies","url":"https://pubmed.ncbi.nlm.nih.gov/31127036","citation_count":6,"is_preprint":false},{"pmid":"39874729","id":"PMC_39874729","title":"LncRNA TCL6 regulates miR-876-5p/MYL2 axis to suppress breast cancer progression.","date":"2025","source":"Translational oncology","url":"https://pubmed.ncbi.nlm.nih.gov/39874729","citation_count":5,"is_preprint":false},{"pmid":"39152369","id":"PMC_39152369","title":"Single-cell transcriptomics reveals writers of RNA modification-mediated immune microenvironment and cardiac resident Macro-MYL2 macrophages in heart failure.","date":"2024","source":"BMC cardiovascular disorders","url":"https://pubmed.ncbi.nlm.nih.gov/39152369","citation_count":4,"is_preprint":false},{"pmid":"34596111","id":"PMC_34596111","title":"MYL2 as a potential predictive biomarker for rhabdomyosarcoma.","date":"2021","source":"Medicine","url":"https://pubmed.ncbi.nlm.nih.gov/34596111","citation_count":4,"is_preprint":false},{"pmid":"29549657","id":"PMC_29549657","title":"A Novel Missense Mutation p.Gly162Glu of the Gene MYL2 Involved in Hypertrophic Cardiomyopathy: A Pedigree Analysis of a Proband.","date":"2018","source":"Molecular diagnosis & therapy","url":"https://pubmed.ncbi.nlm.nih.gov/29549657","citation_count":4,"is_preprint":false},{"pmid":"26763873","id":"PMC_26763873","title":"Effect of obesity on the association between MYL2 (rs3782889) and high-density lipoprotein cholesterol among Korean men.","date":"2016","source":"Journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/26763873","citation_count":4,"is_preprint":false},{"pmid":"33731536","id":"PMC_33731536","title":"Poor Myocardial Compaction in a Patient with Recessive MYL2 Myopathy.","date":"2021","source":"International heart journal","url":"https://pubmed.ncbi.nlm.nih.gov/33731536","citation_count":4,"is_preprint":false},{"pmid":"41330421","id":"PMC_41330421","title":"Osimertinib induces reversible cardiac dysfunction through the GATA4-MYLK3-MYL2 axis.","date":"2026","source":"European heart journal","url":"https://pubmed.ncbi.nlm.nih.gov/41330421","citation_count":3,"is_preprint":false},{"pmid":"40754120","id":"PMC_40754120","title":"Tetramethylpyrazine protects against myocardial ischemia/reperfusion injury via regulating Myl2-mediated NLRP3 signaling pathway inhibition.","date":"2025","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/40754120","citation_count":3,"is_preprint":false},{"pmid":"28212632","id":"PMC_28212632","title":"Exome-wide association study identifies genetic polymorphisms of C12orf51, MYL2, and ALDH2 associated with blood lead levels in the general Korean population.","date":"2017","source":"Environmental health : a global access science source","url":"https://pubmed.ncbi.nlm.nih.gov/28212632","citation_count":3,"is_preprint":false},{"pmid":"30161304","id":"PMC_30161304","title":"[Expression of the MYL2 gene in the development of rat testis tissue].","date":"2018","source":"Zhonghua nan ke xue = National journal of andrology","url":"https://pubmed.ncbi.nlm.nih.gov/30161304","citation_count":1,"is_preprint":false},{"pmid":"41123758","id":"PMC_41123758","title":"LncRNA MYL2 Acts as a Sponge for miR-661 to Regulate Postoperative Cognitive Dysfunction.","date":"2025","source":"Journal of molecular neuroscience : MN","url":"https://pubmed.ncbi.nlm.nih.gov/41123758","citation_count":1,"is_preprint":false},{"pmid":"39532004","id":"PMC_39532004","title":"Neuroprotective effects of Elaeagnus glabra f. oxyphylla extract in amyloid-beta-induced cognitive deficit mice: Involvement of the PKC-delta, MYL2, and FER pathways.","date":"2024","source":"Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie","url":"https://pubmed.ncbi.nlm.nih.gov/39532004","citation_count":1,"is_preprint":false},{"pmid":"40933521","id":"PMC_40933521","title":"WGCNA-based analysis of MYL2 and its relationship with muscle fiber development during the embryonic stage in Inner Mongolia Albas White Cashmere Goats.","date":"2025","source":"Frontiers in veterinary science","url":"https://pubmed.ncbi.nlm.nih.gov/40933521","citation_count":1,"is_preprint":false},{"pmid":"40686275","id":"PMC_40686275","title":"Overexpression of Myl2 Inspires Thermogenic Potential of BAT by Enhancing Adipogenic Differentiation of Brown Adipose Derived Stem Cells.","date":"2025","source":"Journal of cellular physiology","url":"https://pubmed.ncbi.nlm.nih.gov/40686275","citation_count":0,"is_preprint":false},{"pmid":"41999369","id":"PMC_41999369","title":"Ventricular Tachycardia in a Young Athlete With Prior Myocarditis and MYL2 Mutation.","date":"2026","source":"JACC. Case reports","url":"https://pubmed.ncbi.nlm.nih.gov/41999369","citation_count":0,"is_preprint":false},{"pmid":"42074559","id":"PMC_42074559","title":"Fatal Infantile Cardiomyopathy Associated with a Homozygous MYL2 c.413T>A (p.Met138Lys) Variant: A Case Expanding the Recessive MYL2 Phenotypic Spectrum.","date":"2026","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/42074559","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.10.03.680256","title":"Thick filament molecular interfaces play a critical role in pathogenesis of hypertrophic and dilated cardiomyopathy","date":"2025-10-04","source":"bioRxiv","url":"https://doi.org/10.1101/2025.10.03.680256","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.05.02.651878","title":"Advanced Cardiac Organoid Model for Studying Doxorubicin-Induced Cardiotoxicity","date":"2025-05-08","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.02.651878","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":19916,"output_tokens":3538,"usd":0.056409,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":11186,"output_tokens":4269,"usd":0.081327,"stage2_stop_reason":"end_turn"},"total_usd":0.137736,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2015,\n      \"finding\": \"MYL2 (MLC-2v) phosphorylation at Ser15 by myosin light chain kinase displays a specific spatial pattern (high in epicardium, low in endocardium) and directly regulates cross-bridge cycling kinetics and calcium-dependent cardiac muscle contraction, as established by genetic mouse models and computational studies.\",\n      \"method\": \"Genetic mouse models, computational modeling, phosphorylation assays\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple genetic mouse models and orthogonal methods (echocardiography, contractile mechanics, phosphorylation assays) reviewed from multiple labs, but this is a review paper summarizing prior work rather than a single primary study\",\n      \"pmids\": [\"26074085\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MYL2 encodes the myosin regulatory light chain (MLC-2V) that binds to the flexible neck region of the myosin heavy chain in the hexameric myosin complex; recessive loss-of-function mutations disrupting the second EF-hand domain of MYL2 cause cardioskeletal myopathy, establishing a structural/regulatory role in muscle contraction.\",\n      \"method\": \"Linkage analysis, exome sequencing, immunohistochemistry, splice site mutation characterization\",\n      \"journal\": \"Brain\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic mapping plus immunohistochemical verification of absent/abnormal protein in patient muscle; single study but orthogonal methods\",\n      \"pmids\": [\"23365102\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The DCM-associated MYL2 D94A mutation reduces α-helical content of RLC, impairs RLC binding to myosin heavy chain and incorporation into myosin, and increases actin-activated ATPase activity of reconstituted porcine cardiac myosin, without altering calcium sensitivity of force.\",\n      \"method\": \"Recombinant protein purification, in vitro reconstitution into RLC-depleted porcine cardiac preparations, circular dichroism, actin-activated ATPase assay, skinned muscle force measurements\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with purified proteins, mutagenesis, multiple orthogonal functional assays (ATPase, force, structural), single lab\",\n      \"pmids\": [\"25825243\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Transgenic D94A (MYL2) mice develop dilated cardiomyopathy with reduced ejection fraction and left ventricular dilation; D94A myosin motors show reduced actin-activated ATPase activity, rightward shift of force-pCa dependence, and X-ray diffraction reveals repositioning of cross-bridge mass toward thick-filament backbone, consistent with a hypocontractile state.\",\n      \"method\": \"Transgenic mouse model, echocardiography, invasive hemodynamics, small-angle X-ray diffraction, actin-activated ATPase assay, force-pCa measurements\",\n      \"journal\": \"PNAS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vivo transgenic model combined with multiple orthogonal structural and functional assays (X-ray diffraction, ATPase, force-pCa, hemodynamics) in a single rigorous study\",\n      \"pmids\": [\"29463717\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The IVS6-1 splice-site mutation in MYL2 causes a frameshift replacing the last 32 codons; recombinant IVS6-1 RLC shows decreased binding to myosin heavy chain, reduced actin-binding in rigor, lower Vmax of actin-activated myosin ATPase, slower ATP-induced dissociation of acto-myosin complex, and reduced maximal contractile force with increased Ca2+ sensitivity in reconstituted porcine cardiac muscle preparations.\",\n      \"method\": \"Recombinant protein production, in vitro reconstitution into RLC-depleted porcine cardiac preparations, actin-activated ATPase assay, stopped-flow kinetics, skinned muscle force/pCa measurements\",\n      \"journal\": \"Frontiers in physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — full in vitro reconstitution with multiple orthogonal assays (ATPase, stopped-flow kinetics, force-pCa, binding assays), single lab\",\n      \"pmids\": [\"27378946\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"HCM-D166V mutation in MYL2 increases Ca2+ sensitivity of force and promotes premature cross-bridge movement toward thin filaments (left-shifted I11/I10-pCa by X-ray diffraction), disrupts the super-relaxed (SRX) myosin state, and promotes SRX-to-DRX transition correlating with hypercontractility; DCM-D94A favors the energy-conserving SRX state.\",\n      \"method\": \"Small-angle X-ray diffraction simultaneous with isometric force measurements on skinned papillary muscles, ATP turnover assays for SRX/DRX states, transgenic mouse models\",\n      \"journal\": \"PNAS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — simultaneous X-ray diffraction and force measurements with SRX/DRX energetic assays, two transgenic mouse models compared, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"35177471\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"AAV9 delivery of phosphomimetic S15D-RLC (MYL2 Ser15Asp) into HCM-D166V transgenic mice improves cardiac output, stroke work, relaxation (reduced Tau), longitudinal strain, and contractile force in skinned papillary muscles, demonstrating that Ser15 phosphorylation of MYL2 is functionally critical for HCM-D166V cardiac dysfunction.\",\n      \"method\": \"AAV9 gene delivery in transgenic mice, echocardiography, pressure-volume loop hemodynamics, strain analysis, skinned papillary muscle force measurements\",\n      \"journal\": \"Journal of molecular medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo gene therapy rescue with multiple functional readouts (hemodynamics, echocardiography, muscle mechanics) in a disease-relevant transgenic mouse model, single lab\",\n      \"pmids\": [\"31101927\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MYL2-R58Q iPSC-derived cardiomyocytes exhibit hypertrophy (~30% larger), myofibrillar disarray, decreased peak calcium transients, delayed calcium decay, and ~45% reduction in L-type Ca2+ channel (ICa,L) current density, establishing that this MYL2 mutation directly perturbs calcium handling in cardiomyocytes.\",\n      \"method\": \"iPSC-derived cardiomyocytes from R58Q HCM patient, calcium imaging, patch-clamp electrophysiology, immunostaining\",\n      \"journal\": \"Journal of cardiovascular translational research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — patient-specific iPSC-CM model with multiple orthogonal functional readouts (calcium imaging, electrophysiology, cell morphometry), single lab\",\n      \"pmids\": [\"30796699\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"A recessive frameshift MYL2-fs variant causes active proteasomal degradation of the mutant MYL2 protein (rescuable by proteasome inhibitors), while an HCM-associated missense variant (G162R) and stop-gain variants lacking EF domains are stably expressed but show impaired subcellular localization; in a Drosophila Mlc2 knockdown model, neither MYL2-fs nor G162R supports normal cardiac function.\",\n      \"method\": \"In vitro overexpression with proteasome inhibitor rescue, immunohistochemistry on patient tissue, Drosophila in vivo rescue assay, exome sequencing\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — proteasome inhibitor rescue experiment plus in vivo Drosophila functional assay, multiple orthogonal approaches, single lab\",\n      \"pmids\": [\"32453731\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Osimertinib causes reversible cardiac dysfunction via GATA4 dephosphorylation, which suppresses MYLK3 transcription, leading to decreased MYL2 phosphorylation and sarcomere disarray; myosin activator omecamtiv prevents this cardiotoxicity.\",\n      \"method\": \"iPSC-CM in vitro model, snRNA-seq of mouse heart tissue, in vivo mouse model with transverse aortic constriction, pharmacological rescue with omecamtiv\",\n      \"journal\": \"European heart journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro and in vivo models with snRNA-seq and pharmacological rescue, single lab, multiple orthogonal approaches identifying GATA4-MYLK3-MYL2 axis\",\n      \"pmids\": [\"41330421\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Tetramethylpyrazine (TMP) directly binds to MYL2 (identified by DARTS and LC-MS/MS), increases MYL2 protein levels dose-dependently in ischemia/reperfusion-injured cells and heart tissue, and inhibits NLRP3 inflammasome activation and caspase-1-dependent pyroptosis; siRNA knockdown of MYL2 abolishes TMP's cardioprotective effects, placing MYL2 upstream of NLRP3 signaling.\",\n      \"method\": \"DARTS assay, LC-MS/MS, siRNA knockdown, NLRP3 inhibitor/agonist pharmacology, in vivo rat I/R model, in vitro H/R model\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — direct target identification by DARTS/MS plus epistatic siRNA knockdown, in vitro and in vivo models, single lab\",\n      \"pmids\": [\"40754120\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1992,\n      \"finding\": \"The MYL2 gene was mapped to human chromosome 12q23-q24.3 by somatic cell hybrid analysis and in situ hybridization, and was noted to regulate myosin ATPase activity.\",\n      \"method\": \"Southern blot of somatic cell hybrids, in situ hybridization to metaphase chromosomes\",\n      \"journal\": \"Genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal physical mapping methods establishing chromosomal localization, single lab\",\n      \"pmids\": [\"1386340\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Pathogenic HCM missense variants in MYL2 (regulatory light chain) cluster in specific molecular interfaces of the myosin interacting-heads motif (IHM) and heavy chain interfaces within the cardiac thick filament; pathogenic DCM missense variants in MYL2 alter only IHM and myosin tail interfaces; benign variants do not map to any interface, establishing that thick filament molecular interfaces are mechanistically critical for cardiomyopathy pathogenesis.\",\n      \"method\": \"Cryo-EM-based atomic model of human cardiac thick filament; mapping of >200 pathogenic and benign missense variants; clinical outcome correlation\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — cryo-EM structural mapping is high quality but this is a preprint, structural inference without direct mutagenesis validation of each MYL2 variant interface\",\n      \"pmids\": [\"bio_10.1101_2025.10.03.680256\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"MYL2 (ventricular myosin regulatory light chain, MLC-2v) is a ~19 kDa sarcomeric protein that binds the myosin heavy chain neck region, where its phosphorylation at Ser15 by MYLK3 (regulated by the GATA4-MYLK3-MYL2 axis) controls cross-bridge cycling kinetics, super-relaxed myosin state equilibrium, calcium sensitivity of force, and cardiac torsion; pathogenic missense mutations (e.g., D166V causing HCM hypercontractility via SRX disruption; D94A causing DCM hypocontractility via favored SRX and reduced ATPase) and recessive loss-of-function mutations (disrupting the EF-hand domain and MHC binding) each distinctly derange sarcomere mechanics and calcium handling, while MYL2 also participates upstream of NLRP3 inflammasome signaling in cardiac ischemia-reperfusion injury.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MYL2 encodes the ventricular myosin regulatory light chain (MLC-2v), which binds the flexible neck region of the myosin heavy chain in the hexameric sarcomeric myosin and thereby governs cross-bridge cycling kinetics, calcium-dependent contractile force, and the equilibrium between super-relaxed (SRX) and disordered-relaxed (DRX) myosin states [#1, #5]. Phosphorylation of MYL2 at Ser15 by myosin light chain kinase tunes cross-bridge cycling and calcium-dependent contraction, displaying a transmural gradient (high epicardium, low endocardium), and the GATA4–MYLK3–MYL2 transcriptional/phosphorylation axis sets the steady-state level of this modification [#0, #9]. Distinct missense substitutions derange sarcomere mechanics in opposite directions: the HCM-associated D166V mutation increases calcium sensitivity of force and shifts myosin out of the energy-conserving SRX state toward a hypercontractile DRX state, whereas the DCM-associated D94A mutation reduces RLC \\u03b1-helical content and myosin incorporation, alters actin-activated ATPase, and favors the SRX state, producing a hypocontractile, dilated phenotype [#2, #3, #5]. Restoring Ser15 phosphorylation via phosphomimetic S15D rescues contractile and relaxation defects in HCM-D166V hearts, demonstrating the causal role of this regulatory site [#6]. Recessive loss-of-function and frameshift variants that disrupt the second EF-hand domain and heavy-chain binding\\u2014some triggering proteasomal degradation or mislocalization of the mutant protein\\u2014cause cardioskeletal myopathy, and pathogenic variants map preferentially to myosin interacting-heads-motif and heavy-chain interfaces of the thick filament [#1, #8]. Beyond the sarcomere, MYL2 acts upstream of NLRP3 inflammasome activation and caspase-1\\u2013dependent pyroptosis in cardiac ischemia\\u2013reperfusion injury [#10].\",\n  \"teleology\": [\n    {\n      \"year\": 1992,\n      \"claim\": \"Establishing the chromosomal location and a basic regulatory role for MYL2 provided the genomic foothold for later disease-gene mapping.\",\n      \"evidence\": \"Somatic cell hybrid Southern blot and in situ hybridization placing MYL2 at 12q23-q24.3\",\n      \"pmids\": [\"1386340\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional mechanism beyond noting regulation of myosin ATPase\", \"No mutation-phenotype link yet\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defining MYL2 as the regulatory light chain bound to the myosin neck and linking EF-hand-disrupting recessive loss-of-function to cardioskeletal myopathy fixed its structural role in muscle contraction.\",\n      \"evidence\": \"Linkage analysis, exome sequencing, and immunohistochemistry of patient muscle for a splice-site mutation\",\n      \"pmids\": [\"23365102\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Biochemical consequences of EF-hand disruption not reconstituted\", \"Skeletal vs cardiac contribution not dissected\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Reconstitution showed how a DCM mutation acts at the molecular level\\u2014weakening RLC structure, myosin incorporation, and altering ATPase\\u2014moving beyond genetic association to biochemical causation.\",\n      \"evidence\": \"Recombinant D94A RLC reconstituted into RLC-depleted porcine cardiac preparations with CD, actin-activated ATPase, and skinned-fiber force assays\",\n      \"pmids\": [\"25825243\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo cardiac consequences not yet tested\", \"Effect on SRX state not assessed in this study\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Spatially resolved Ser15 phosphorylation by MLCK was tied to cross-bridge kinetics and calcium-dependent contraction, defining the regulatory modification of MYL2.\",\n      \"evidence\": \"Review synthesizing genetic mouse models, computational modeling, and phosphorylation assays\",\n      \"pmids\": [\"26074085\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Review-level synthesis rather than single primary dataset\", \"Kinase identity and upstream control not resolved here\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"An in vivo transgenic model confirmed D94A causes dilated cardiomyopathy and linked the phenotype to reduced ATPase, rightward force-pCa shift, and structural repositioning of cross-bridges\\u2014establishing a hypocontractile mechanism.\",\n      \"evidence\": \"D94A transgenic mice with echocardiography, hemodynamics, small-angle X-ray diffraction, ATPase and force-pCa measurements\",\n      \"pmids\": [\"29463717\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"SRX/DRX contribution clarified only in later work\", \"Therapeutic reversibility not tested\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Characterizing a frameshift splice-site variant defined how C-terminal truncation impairs myosin and actin binding, ATPase, and contractile force, broadening the loss-of-function mechanism.\",\n      \"evidence\": \"Recombinant IVS6-1 RLC reconstituted into porcine cardiac preparations with ATPase, stopped-flow kinetics, and force/pCa assays\",\n      \"pmids\": [\"27378946\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo cardiac phenotype not established\", \"Relationship to recessive myopathy variants not dissected\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Phosphomimetic rescue demonstrated that Ser15 phosphorylation is functionally decisive, converting a regulatory observation into a therapeutic principle for MYL2-driven HCM.\",\n      \"evidence\": \"AAV9 delivery of S15D-RLC into HCM-D166V transgenic mice with hemodynamics, strain, and skinned-fiber force\",\n      \"pmids\": [\"31101927\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Durability and off-target effects of gene therapy not addressed\", \"Applicability to other MYL2 mutations untested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Patient-derived iPSC-cardiomyocytes connected an HCM MYL2 mutation to disrupted calcium handling and L-type channel current, extending pathology to excitation-contraction coupling.\",\n      \"evidence\": \"R58Q iPSC-CMs with calcium imaging, patch-clamp electrophysiology, and morphometry\",\n      \"pmids\": [\"30796699\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic link between RLC and ICa,L reduction unresolved\", \"Single-cell model lacks tissue-level context\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Variant-specific fates\\u2014proteasomal degradation of a frameshift allele versus mislocalization of stable missense/stop-gain proteins\\u2014explained how different MYL2 alleles fail, with in vivo confirmation.\",\n      \"evidence\": \"Overexpression with proteasome-inhibitor rescue, patient-tissue immunohistochemistry, and Drosophila Mlc2 knockdown rescue\",\n      \"pmids\": [\"32453731\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Degradation pathway components not identified\", \"Quantitative contribution of mislocalization to human phenotype unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Simultaneous X-ray diffraction, force, and ATP-turnover assays unified HCM and DCM mechanisms around the SRX/DRX equilibrium\\u2014D166V destabilizing SRX (hypercontractility) and D94A favoring SRX (hypocontractility).\",\n      \"evidence\": \"Skinned papillary muscle X-ray diffraction with isometric force and SRX/DRX ATP turnover assays in two transgenic mouse lines\",\n      \"pmids\": [\"35177471\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How RLC mutations bias the IHM at atomic resolution not directly shown\", \"Phosphorylation interplay with SRX not fully mapped\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A thick-filament cryo-EM model showed pathogenic HCM and DCM variants cluster at distinct myosin interacting-heads-motif and heavy-chain interfaces while benign variants avoid them, providing a structural framework for genotype interpretation.\",\n      \"evidence\": \"Cryo-EM atomic model of human cardiac thick filament with mapping of >200 variants and clinical outcome correlation (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.10.03.680256\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural inference not validated by per-variant mutagenesis\", \"Preprint, not peer-reviewed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identifying MYL2 as a direct tetramethylpyrazine target acting upstream of NLRP3 revealed a non-sarcomeric, inflammatory-protective role in ischemia-reperfusion injury.\",\n      \"evidence\": \"DARTS/LC-MS/MS target identification, siRNA knockdown epistasis, NLRP3 pharmacology, and in vitro/in vivo I-R models\",\n      \"pmids\": [\"40754120\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular link between MYL2 and NLRP3 not defined\", \"Whether the effect is sarcomere-independent unclear\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Mapping a GATA4\\u2013MYLK3\\u2013MYL2 axis explained drug-induced reversible cardiotoxicity as loss of MYL2 phosphorylation, linking transcriptional control of the kinase to sarcomere function.\",\n      \"evidence\": \"iPSC-CM model, snRNA-seq of mouse heart, transverse aortic constriction in vivo, and omecamtiv pharmacological rescue\",\n      \"pmids\": [\"41330421\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct GATA4 occupancy at MYLK3 not detailed here\", \"Generalizability beyond osimertinib not established\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How MYL2 mechanistically couples to NLRP3 inflammasome signaling and to L-type calcium channel regulation, distinct from its sarcomeric role, remains unresolved.\",\n      \"evidence\": null,\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No molecular intermediary between MYL2 and NLRP3 identified\", \"Mechanism linking RLC mutation to ICa,L reduction unknown\", \"Phosphorylation-IHM-SRX interplay not resolved at atomic resolution\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [1, 2, 4]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 5, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005863\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-397014\", \"supporting_discovery_ids\": [0, 1, 5]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [2, 3, 5, 8]}\n    ],\n    \"complexes\": [\"cardiac thick filament (sarcomeric myosin hexamer)\"],\n    \"partners\": [\"MYH7\", \"MYLK3\", \"GATA4\", \"NLRP3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}