{"gene":"MYL2","run_date":"2026-04-29T11:37:56","timeline":{"discoveries":[{"year":2015,"finding":"MYL2 (MLC-2v) phosphorylation at Ser15 by myosin light chain kinase directly regulates cross-bridge cycling kinetics, calcium-dependent cardiac muscle contraction, and cardiac torsion; phosphorylation displays a specific spatial pattern (high in epicardium, low in endocardium) across the adult heart.","method":"Genetic mouse models, computational models, and in vitro phosphorylation assays; loss-of-function studies in mice demonstrating essential role in cardiac contractile function","journal":"Gene","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal methods across multiple labs, replicated findings in genetic models and biochemical assays","pmids":["26074085"],"is_preprint":false},{"year":2015,"finding":"The DCM-associated D94A mutation in MYL2 reduces α-helical content of RLC, impairs binding of RLC to the myosin heavy chain, reduces RLC incorporation into myosin, and significantly increases actin-activated ATPase activity of mutant-reconstituted porcine cardiac myosin, without affecting calcium sensitivity of force.","method":"Recombinant protein expression, circular dichroism (structural analysis), actin-activated ATPase assay, RLC-depleted porcine cardiac myosin reconstitution, skinned papillary muscle force measurements","journal":"The FEBS journal","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with multiple orthogonal functional assays and mutagenesis in a single rigorous study","pmids":["25825243"],"is_preprint":false},{"year":2018,"finding":"Transgenic D94A (DCM) MYL2 mice show decreased actin-activated myosin ATPase activity, rightward shift of force-pCa dependence (decreased Ca2+ sensitivity), and repositioning of cross-bridge mass toward thick-filament backbone at submaximal Ca2+ concentrations, leading to left ventricular dilation and reduced ejection fraction.","method":"Transgenic mouse model, echocardiography, invasive hemodynamics, skinned fiber force-pCa measurements, small-angle X-ray diffraction","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal in vivo and in vitro methods in transgenic mouse model with structural and functional readouts","pmids":["29463717"],"is_preprint":false},{"year":2022,"finding":"The HCM-D166V MYL2 mutation disrupts the super-relaxed (SRX) state of myosin, promoting SRX-to-DRX transition, moving cross-bridges closer to actin thin filaments, and increasing Ca2+ sensitivity of force. The DCM-D94A mutation favors the energy-conserving SRX state. These mutation-induced redistributions of myosin energetic states are key mechanisms underlying the distinct HCM vs DCM phenotypes.","method":"Small-angle X-ray diffraction simultaneous with isometric force measurements in skinned papillary muscles, ATP-dependent myosin energetic state assays, force-pCa relationship measurements","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — reconstitution and structural assays with multiple orthogonal methods in defined mouse cardiomyopathy models","pmids":["35177471"],"is_preprint":false},{"year":2016,"finding":"The IVS6-1 splice site mutation in MYL2 produces a mutant RLC with decreased binding to myosin heavy chain, reduced acto-myosin rigor binding, lower maximal actin-activated ATPase activity (Vmax), slower ATP-induced dissociation kinetics of acto-myosin, decreased maximal contractile force, and increased Ca2+ sensitivity of force—hallmarks of HCM-associated mutations.","method":"Recombinant human cardiac IVS6-1 and WT RLC proteins reconstituted into RLC-depleted porcine cardiac preparations; actin-activated ATPase assay; stopped-flow kinetics; skinned porcine cardiac muscle force measurements","journal":"Frontiers in physiology","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with multiple orthogonal enzymatic, kinetic, and mechanical functional assays","pmids":["27378946"],"is_preprint":false},{"year":2013,"finding":"MYL2 encodes a myosin regulatory light chain that binds to the flexible neck region of myosin heavy chain in the hexameric myosin complex; recessive loss-of-function mutations disrupting the C-terminal EF-hand domain (which functions as a calcium sensor) cause cardioskeletal myopathy with myofibrillar disorganization, as shown by immunohistochemistry demonstrating diffuse, weak expression of mutant protein without fiber specificity and absence of normal protein.","method":"Linkage analysis, exome sequencing, splice site mutation identification, immunohistochemical staining of patient skeletal muscle tissue","journal":"Brain : a journal of neurology","confidence":"Medium","confidence_rationale":"Tier 2–3 — genetic and immunohistochemical evidence in patient tissue; mechanistic inference from domain disruption without direct in vitro reconstitution","pmids":["23365102"],"is_preprint":false},{"year":2019,"finding":"AAV9-mediated delivery of phosphomimetic S15D-RLC (Ser15-to-Asp substitution at the MYL2 phosphorylation site) into HCM-D166V mouse hearts improves cardiac output, stroke work, relaxation, and maximal contractile force, demonstrating that RLC phosphorylation at Ser15 is functionally critical for normal cardiac function and has therapeutic potential.","method":"AAV9 gene delivery in transgenic HCM-D166V mice; echocardiography; invasive hemodynamics (PV loops); skinned papillary muscle mechanics; strain analysis","journal":"Journal of molecular medicine (Berlin, Germany)","confidence":"High","confidence_rationale":"Tier 2 — in vivo gene therapy with multiple orthogonal functional readouts in defined transgenic disease model","pmids":["31101927"],"is_preprint":false},{"year":2019,"finding":"MYL2-R58Q iPSC-derived cardiomyocytes show cellular hypertrophy (~30% larger), myofibrillar disarray, decreased peak calcium transients, delayed calcium decay, and ~45% reduction in L-type Ca2+ channel current density, demonstrating that R58Q perturbs calcium handling and sarcomere organization at the cellular level.","method":"Patient-specific iPSC-CM model; cell size measurements; calcium imaging; patch-clamp electrophysiology","journal":"Journal of cardiovascular translational research","confidence":"Medium","confidence_rationale":"Tier 2 — iPSC-CM disease model with multiple orthogonal cellular and electrophysiological measurements in a single study","pmids":["30796699"],"is_preprint":false},{"year":2020,"finding":"A recessive frameshift MYL2 variant (c.431_432delCT) is actively degraded via the proteasome (rescue by proteasome inhibition), whereas HCM-associated missense variant G162R and truncating variants losing EF-hand domains are stably expressed but show impaired localization; in vivo Drosophila Mlc2 knockdown rescue experiments confirm that neither the frameshift nor G162R variant supports normal cardiac function.","method":"Exome sequencing; in vitro overexpression; immunohistochemistry; proteasome inhibitor rescue; Drosophila in vivo rescue experiments","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods including in vivo Drosophila rescue and proteasome inhibitor rescue in single study","pmids":["32453731"],"is_preprint":false},{"year":2026,"finding":"Osimertinib causes cardiac dysfunction by reducing GATA4 phosphorylation, which suppresses MYLK3 transcription, leading to decreased MYL2 phosphorylation and sarcomere disarray; this mechanism is reversible upon drug discontinuation and prevented by myosin activator omecamtiv.","method":"Single-nucleus RNA sequencing; iPSC-CM in vitro assays; mouse in vivo model (transverse aortic constriction); pharmacological intervention","journal":"European heart journal","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods (snRNA-seq, in vitro, in vivo) in a single study identifying GATA4-MYLK3-MYL2 axis","pmids":["41330421"],"is_preprint":false},{"year":2025,"finding":"MYL2 pathogenic and benign missense variants map to distinct molecular interfaces of the cardiac thick filament interactome; HCM variants cluster at 31 interfaces including the two main interacting-heads motif (IHM) interfaces involving myosin heavy chain, essential and regulatory light chains, and cMyBP-C; DCM variants alter only IHM and tail interfaces; variants within interfaces associate with earlier disease onset and adverse outcomes.","method":"Cryo-EM-based atomic model of human cardiac thick filament; systematic mapping of >200 pathogenic and benign missense variants; clinical outcome analysis","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 1 — cryo-EM structural mapping with clinical correlation, but preprint and single study","pmids":["bio_10.1101_2025.10.03.680256"],"is_preprint":true},{"year":2025,"finding":"TMP (tetramethylpyrazine) directly binds MYL2 protein (identified by DARTS and LC-MS/MS), increases MYL2 protein levels, and MYL2 upregulation inhibits NLRP3 inflammasome activation; siRNA knockdown of Myl2 negates TMP's cardioprotective effects against ischemia/reperfusion injury.","method":"DARTS (drug affinity responsive target stability); LC-MS/MS; siRNA knockdown; NLRP3 inflammasome assays; rat MIRI model and H9c2 H/R model","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 — direct binding identified by DARTS/MS with functional validation by siRNA knockdown in vitro and in vivo","pmids":["40754120"],"is_preprint":false}],"current_model":"MYL2 encodes the cardiac ventricular regulatory myosin light chain (RLC) that binds the myosin heavy chain neck region and regulates sarcomere function through phosphorylation at Ser15 (by MYLK3, downstream of GATA4), which controls cross-bridge cycling kinetics, calcium sensitivity of force, and the super-relaxed (SRX) ↔ disordered-relaxed (DRX) equilibrium of myosin; pathogenic mutations (e.g., D166V causing HCM, D94A causing DCM) alter these structural and energetic states, RLC–MHC binding, and ATPase activity to produce distinct cardiomyopathy phenotypes, while recessive loss-of-function variants cause MYL2 protein degradation or mislocalization leading to infantile cardioskeletal myopathy."},"narrative":{"teleology":[{"year":2013,"claim":"Establishing that recessive MYL2 mutations cause human disease resolved whether RLC loss-of-function is tolerated: biallelic mutations disrupting the C-terminal EF-hand domain cause cardioskeletal myopathy with loss of normal RLC protein expression and myofibrillar disorganization.","evidence":"Linkage analysis, exome sequencing, and immunohistochemistry of patient skeletal muscle","pmids":["23365102"],"confidence":"Medium","gaps":["No in vitro reconstitution of mutant RLC function","Mechanism of protein loss (degradation vs. misfolding) not determined","Skeletal muscle involvement mechanism unclear"]},{"year":2015,"claim":"Defining the functional consequences of MYL2 phosphorylation at Ser15 established that RLC phosphorylation directly regulates cross-bridge cycling kinetics, calcium-dependent contraction, and cardiac torsion, with a specific transmural gradient across the ventricular wall.","evidence":"Genetic mouse models with phosphorylation-site mutations, computational models, and in vitro phosphorylation assays","pmids":["26074085"],"confidence":"High","gaps":["Kinase(s) responsible for the spatial phosphorylation gradient not fully defined in vivo","Whether phosphorylation acts through SRX/DRX transitions was not yet tested"]},{"year":2015,"claim":"Characterizing the DCM-associated D94A mutation in vitro revealed that a disease-causing RLC variant reduces α-helical content, impairs RLC–MHC binding and incorporation, and paradoxically increases actin-activated ATPase activity, establishing that RLC structural integrity controls myosin enzymatic function.","evidence":"Recombinant RLC expression, circular dichroism, ATPase assays, and reconstitution into RLC-depleted porcine cardiac myosin","pmids":["25825243"],"confidence":"High","gaps":["In vitro ATPase increase contradicted later in vivo findings","Cross-bridge structural positioning not assessed"]},{"year":2016,"claim":"Analysis of the HCM-associated IVS6-1 splice site mutation demonstrated that it impairs RLC–MHC binding, slows ATP-induced acto-myosin dissociation, and increases calcium sensitivity of force, defining a shared functional signature among HCM-causing RLC mutations.","evidence":"Reconstitution of recombinant IVS6-1 RLC into depleted porcine cardiac preparations with ATPase, stopped-flow kinetics, and skinned muscle force assays","pmids":["27378946"],"confidence":"High","gaps":["No in vivo validation of this splice variant","Whether this variant alters SRX/DRX balance was unknown"]},{"year":2018,"claim":"Transgenic D94A mice resolved a discrepancy between in vitro and in vivo ATPase effects and showed that DCM-D94A decreases calcium sensitivity and repositions cross-bridges toward the thick-filament backbone, directly linking RLC mutation to ventricular dilation and reduced ejection fraction in vivo.","evidence":"Transgenic mouse echocardiography, invasive hemodynamics, skinned fiber force-pCa, and small-angle X-ray diffraction","pmids":["29463717"],"confidence":"High","gaps":["SRX/DRX equilibrium not directly measured","How cross-bridge repositioning mechanistically causes dilation not resolved"]},{"year":2019,"claim":"AAV9-mediated delivery of phosphomimetic S15D-RLC rescued cardiac function in HCM-D166V mice, demonstrating that Ser15 phosphorylation is not merely correlative but causally required for normal contraction and is a viable therapeutic target.","evidence":"AAV9 gene therapy in D166V transgenic mice with echocardiography, PV loops, and skinned papillary muscle mechanics","pmids":["31101927"],"confidence":"High","gaps":["Long-term effects and potential immunogenicity not assessed","Whether S15D also corrects SRX/DRX imbalance was not tested"]},{"year":2019,"claim":"iPSC-derived cardiomyocytes from R58Q patients established that HCM-causing RLC mutations perturb cellular calcium handling (reduced peak transients, decreased L-type Ca²⁺ current) in addition to sarcomere mechanics, broadening the pathomechanism beyond cross-bridge cycling.","evidence":"Patient iPSC-CM model with cell size measurements, calcium imaging, and patch-clamp electrophysiology","pmids":["30796699"],"confidence":"Medium","gaps":["Single patient line; isogenic controls not described","Whether calcium channel effects are primary or secondary to sarcomere dysfunction is unclear"]},{"year":2020,"claim":"Demonstrating that a recessive frameshift MYL2 variant is degraded via the proteasome while HCM missense variants are stably expressed but mislocalized clarified that distinct protein quality control fates underlie recessive vs. dominant MYL2 disease mechanisms.","evidence":"In vitro overexpression with proteasome inhibitor rescue; Drosophila Mlc2 knockdown rescue experiments","pmids":["32453731"],"confidence":"Medium","gaps":["Proteasome degradation shown by inhibitor rescue, not by direct ubiquitination assay","Drosophila Mlc2 is not identical to human MYL2"]},{"year":2022,"claim":"Simultaneous X-ray diffraction and force measurements in D166V and D94A mouse hearts unified the SRX/DRX framework for RLC mutations: HCM-D166V destabilizes SRX (shifting myosin toward DRX/actin), while DCM-D94A stabilizes SRX, providing an energetic basis for opposing cardiomyopathy phenotypes.","evidence":"Small-angle X-ray diffraction with isometric force in skinned papillary muscles; mant-ATP SRX/DRX assays","pmids":["35177471"],"confidence":"High","gaps":["Whether phosphorylation state modulates the SRX/DRX effect of each mutation was not tested","Structural basis at atomic resolution was lacking"]},{"year":2025,"claim":"Identification of the GATA4→MYLK3→MYL2 phosphorylation axis as the mechanism of osimertinib-induced cardiotoxicity placed MYL2 phosphorylation regulation in a defined transcriptional signaling pathway and demonstrated reversibility upon drug withdrawal or myosin activator treatment.","evidence":"snRNA-seq, iPSC-CM assays, mouse TAC model, and pharmacological intervention with omecamtiv mecarbil","pmids":["41330421"],"confidence":"Medium","gaps":["Published year listed as 2026 suggesting early online; independent replication needed","Whether GATA4-MYLK3 is the dominant pathway for MYL2 phosphorylation in physiological conditions is not established"]},{"year":null,"claim":"A complete atomic-resolution understanding of how individual RLC mutations alter the interacting-heads motif (IHM) and thick-filament quaternary structure in the human heart remains unresolved, as does the question of whether SRX/DRX rebalancing is a universal therapeutic target across all MYL2 cardiomyopathy variants.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No high-resolution human cardiac thick-filament structure with mutant RLC","Therapeutic SRX/DRX modulation not tested for recessive loss-of-function variants","In vivo role of MYL2 in NLRP3 inflammasome regulation requires independent confirmation"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0,1,4,5]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,3,6]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[0,1,2,5]}],"pathway":[{"term_id":"R-HSA-397014","term_label":"Muscle contraction","supporting_discovery_ids":[0,1,2,3,4,6]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[1,2,3,5,7,8]}],"complexes":["cardiac myosin (hexameric thick filament complex)"],"partners":["MYH7","MYLK3","GATA4","MYBPC3"],"other_free_text":[]},"mechanistic_narrative":"MYL2 encodes the ventricular regulatory myosin light chain (RLC), a core subunit of the cardiac sarcomeric myosin hexamer that binds the myosin heavy chain neck region and controls cross-bridge cycling kinetics, calcium sensitivity of force, and the equilibrium between the energy-conserving super-relaxed (SRX) and force-generating disordered-relaxed (DRX) states of myosin [PMID:26074085, PMID:35177471]. Phosphorylation of MYL2 at Ser15, catalyzed by MYLK3 downstream of GATA4, is essential for normal cardiac contractile function and displays an epicardial-to-endocardial gradient; its loss leads to sarcomere disarray and cardiac dysfunction [PMID:26074085, PMID:41330421, PMID:31101927]. Pathogenic mutations produce distinct cardiomyopathy phenotypes: HCM-associated variants (e.g., D166V, R58Q, IVS6-1) disrupt the SRX state, increase calcium sensitivity, and cause cellular hypertrophy, whereas the DCM-associated D94A mutation favors SRX, reduces calcium sensitivity, and repositions cross-bridges away from actin [PMID:35177471, PMID:25825243, PMID:29463717, PMID:30796699]. Recessive loss-of-function MYL2 mutations cause infantile cardioskeletal myopathy through protein degradation or mislocalization and loss of normal sarcomeric incorporation [PMID:23365102, PMID:32453731]."},"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":132,"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":66,"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":46,"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":"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":"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":18,"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":5,"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":"34596111","id":"PMC_34596111","title":"MYL2 as a potential predictive biomarker for 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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":"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":3,"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":2,"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":2,"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":"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":"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 : 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Case reports","url":"https://pubmed.ncbi.nlm.nih.gov/41999369","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},{"pmid":null,"id":"bio_10.1101_2024.06.11.598443","title":"Deciphering the regulatory pathways in skeletal muscle lineage organized by the YAP1/TAZ-TEAD transcriptional network","date":"2024-06-13","source":"bioRxiv","url":"https://doi.org/10.1101/2024.06.11.598443","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":19075,"output_tokens":3170,"usd":0.052387},"stage2":{"model":"claude-opus-4-6","input_tokens":6530,"output_tokens":2803,"usd":0.154087},"total_usd":0.206474,"stage1_batch_id":"msgbatch_012ZiiCUBfB62NCTQd4Bk1Jo","stage2_batch_id":"msgbatch_01Xuqq9aUHoQouS7UVGZNStZ","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 directly regulates cross-bridge cycling kinetics, calcium-dependent cardiac muscle contraction, and cardiac torsion; phosphorylation displays a specific spatial pattern (high in epicardium, low in endocardium) across the adult heart.\",\n      \"method\": \"Genetic mouse models, computational models, and in vitro phosphorylation assays; loss-of-function studies in mice demonstrating essential role in cardiac contractile function\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods across multiple labs, replicated findings in genetic models and biochemical assays\",\n      \"pmids\": [\"26074085\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The DCM-associated D94A mutation in MYL2 reduces α-helical content of RLC, impairs binding of RLC to the myosin heavy chain, reduces RLC incorporation into myosin, and significantly increases actin-activated ATPase activity of mutant-reconstituted porcine cardiac myosin, without affecting calcium sensitivity of force.\",\n      \"method\": \"Recombinant protein expression, circular dichroism (structural analysis), actin-activated ATPase assay, RLC-depleted porcine cardiac myosin reconstitution, skinned papillary muscle force measurements\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with multiple orthogonal functional assays and mutagenesis in a single rigorous study\",\n      \"pmids\": [\"25825243\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Transgenic D94A (DCM) MYL2 mice show decreased actin-activated myosin ATPase activity, rightward shift of force-pCa dependence (decreased Ca2+ sensitivity), and repositioning of cross-bridge mass toward thick-filament backbone at submaximal Ca2+ concentrations, leading to left ventricular dilation and reduced ejection fraction.\",\n      \"method\": \"Transgenic mouse model, echocardiography, invasive hemodynamics, skinned fiber force-pCa measurements, small-angle X-ray diffraction\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal in vivo and in vitro methods in transgenic mouse model with structural and functional readouts\",\n      \"pmids\": [\"29463717\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The HCM-D166V MYL2 mutation disrupts the super-relaxed (SRX) state of myosin, promoting SRX-to-DRX transition, moving cross-bridges closer to actin thin filaments, and increasing Ca2+ sensitivity of force. The DCM-D94A mutation favors the energy-conserving SRX state. These mutation-induced redistributions of myosin energetic states are key mechanisms underlying the distinct HCM vs DCM phenotypes.\",\n      \"method\": \"Small-angle X-ray diffraction simultaneous with isometric force measurements in skinned papillary muscles, ATP-dependent myosin energetic state assays, force-pCa relationship measurements\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution and structural assays with multiple orthogonal methods in defined mouse cardiomyopathy models\",\n      \"pmids\": [\"35177471\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The IVS6-1 splice site mutation in MYL2 produces a mutant RLC with decreased binding to myosin heavy chain, reduced acto-myosin rigor binding, lower maximal actin-activated ATPase activity (Vmax), slower ATP-induced dissociation kinetics of acto-myosin, decreased maximal contractile force, and increased Ca2+ sensitivity of force—hallmarks of HCM-associated mutations.\",\n      \"method\": \"Recombinant human cardiac IVS6-1 and WT RLC proteins reconstituted into RLC-depleted porcine cardiac preparations; actin-activated ATPase assay; stopped-flow kinetics; skinned porcine cardiac muscle force measurements\",\n      \"journal\": \"Frontiers in physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with multiple orthogonal enzymatic, kinetic, and mechanical functional assays\",\n      \"pmids\": [\"27378946\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MYL2 encodes a myosin regulatory light chain that binds to the flexible neck region of myosin heavy chain in the hexameric myosin complex; recessive loss-of-function mutations disrupting the C-terminal EF-hand domain (which functions as a calcium sensor) cause cardioskeletal myopathy with myofibrillar disorganization, as shown by immunohistochemistry demonstrating diffuse, weak expression of mutant protein without fiber specificity and absence of normal protein.\",\n      \"method\": \"Linkage analysis, exome sequencing, splice site mutation identification, immunohistochemical staining of patient skeletal muscle tissue\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — genetic and immunohistochemical evidence in patient tissue; mechanistic inference from domain disruption without direct in vitro reconstitution\",\n      \"pmids\": [\"23365102\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"AAV9-mediated delivery of phosphomimetic S15D-RLC (Ser15-to-Asp substitution at the MYL2 phosphorylation site) into HCM-D166V mouse hearts improves cardiac output, stroke work, relaxation, and maximal contractile force, demonstrating that RLC phosphorylation at Ser15 is functionally critical for normal cardiac function and has therapeutic potential.\",\n      \"method\": \"AAV9 gene delivery in transgenic HCM-D166V mice; echocardiography; invasive hemodynamics (PV loops); skinned papillary muscle mechanics; strain analysis\",\n      \"journal\": \"Journal of molecular medicine (Berlin, Germany)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo gene therapy with multiple orthogonal functional readouts in defined transgenic disease model\",\n      \"pmids\": [\"31101927\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MYL2-R58Q iPSC-derived cardiomyocytes show cellular hypertrophy (~30% larger), myofibrillar disarray, decreased peak calcium transients, delayed calcium decay, and ~45% reduction in L-type Ca2+ channel current density, demonstrating that R58Q perturbs calcium handling and sarcomere organization at the cellular level.\",\n      \"method\": \"Patient-specific iPSC-CM model; cell size measurements; calcium imaging; patch-clamp electrophysiology\",\n      \"journal\": \"Journal of cardiovascular translational research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — iPSC-CM disease model with multiple orthogonal cellular and electrophysiological measurements in a single study\",\n      \"pmids\": [\"30796699\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"A recessive frameshift MYL2 variant (c.431_432delCT) is actively degraded via the proteasome (rescue by proteasome inhibition), whereas HCM-associated missense variant G162R and truncating variants losing EF-hand domains are stably expressed but show impaired localization; in vivo Drosophila Mlc2 knockdown rescue experiments confirm that neither the frameshift nor G162R variant supports normal cardiac function.\",\n      \"method\": \"Exome sequencing; in vitro overexpression; immunohistochemistry; proteasome inhibitor rescue; Drosophila in vivo rescue experiments\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods including in vivo Drosophila rescue and proteasome inhibitor rescue in single study\",\n      \"pmids\": [\"32453731\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Osimertinib causes cardiac dysfunction by reducing GATA4 phosphorylation, which suppresses MYLK3 transcription, leading to decreased MYL2 phosphorylation and sarcomere disarray; this mechanism is reversible upon drug discontinuation and prevented by myosin activator omecamtiv.\",\n      \"method\": \"Single-nucleus RNA sequencing; iPSC-CM in vitro assays; mouse in vivo model (transverse aortic constriction); pharmacological intervention\",\n      \"journal\": \"European heart journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (snRNA-seq, in vitro, in vivo) in a single study identifying GATA4-MYLK3-MYL2 axis\",\n      \"pmids\": [\"41330421\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"MYL2 pathogenic and benign missense variants map to distinct molecular interfaces of the cardiac thick filament interactome; HCM variants cluster at 31 interfaces including the two main interacting-heads motif (IHM) interfaces involving myosin heavy chain, essential and regulatory light chains, and cMyBP-C; DCM variants alter only IHM and tail interfaces; variants within interfaces associate with earlier disease onset and adverse outcomes.\",\n      \"method\": \"Cryo-EM-based atomic model of human cardiac thick filament; systematic mapping of >200 pathogenic and benign missense variants; clinical outcome analysis\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structural mapping with clinical correlation, but preprint and single study\",\n      \"pmids\": [\"bio_10.1101_2025.10.03.680256\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"TMP (tetramethylpyrazine) directly binds MYL2 protein (identified by DARTS and LC-MS/MS), increases MYL2 protein levels, and MYL2 upregulation inhibits NLRP3 inflammasome activation; siRNA knockdown of Myl2 negates TMP's cardioprotective effects against ischemia/reperfusion injury.\",\n      \"method\": \"DARTS (drug affinity responsive target stability); LC-MS/MS; siRNA knockdown; NLRP3 inflammasome assays; rat MIRI model and H9c2 H/R model\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct binding identified by DARTS/MS with functional validation by siRNA knockdown in vitro and in vivo\",\n      \"pmids\": [\"40754120\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MYL2 encodes the cardiac ventricular regulatory myosin light chain (RLC) that binds the myosin heavy chain neck region and regulates sarcomere function through phosphorylation at Ser15 (by MYLK3, downstream of GATA4), which controls cross-bridge cycling kinetics, calcium sensitivity of force, and the super-relaxed (SRX) ↔ disordered-relaxed (DRX) equilibrium of myosin; pathogenic mutations (e.g., D166V causing HCM, D94A causing DCM) alter these structural and energetic states, RLC–MHC binding, and ATPase activity to produce distinct cardiomyopathy phenotypes, while recessive loss-of-function variants cause MYL2 protein degradation or mislocalization leading to infantile cardioskeletal myopathy.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"MYL2 encodes the ventricular regulatory myosin light chain (RLC), a core subunit of the cardiac sarcomeric myosin hexamer that binds the myosin heavy chain neck region and controls cross-bridge cycling kinetics, calcium sensitivity of force, and the equilibrium between the energy-conserving super-relaxed (SRX) and force-generating disordered-relaxed (DRX) states of myosin [PMID:26074085, PMID:35177471]. Phosphorylation of MYL2 at Ser15, catalyzed by MYLK3 downstream of GATA4, is essential for normal cardiac contractile function and displays an epicardial-to-endocardial gradient; its loss leads to sarcomere disarray and cardiac dysfunction [PMID:26074085, PMID:41330421, PMID:31101927]. Pathogenic mutations produce distinct cardiomyopathy phenotypes: HCM-associated variants (e.g., D166V, R58Q, IVS6-1) disrupt the SRX state, increase calcium sensitivity, and cause cellular hypertrophy, whereas the DCM-associated D94A mutation favors SRX, reduces calcium sensitivity, and repositions cross-bridges away from actin [PMID:35177471, PMID:25825243, PMID:29463717, PMID:30796699]. Recessive loss-of-function MYL2 mutations cause infantile cardioskeletal myopathy through protein degradation or mislocalization and loss of normal sarcomeric incorporation [PMID:23365102, PMID:32453731].\",\n  \"teleology\": [\n    {\n      \"year\": 2013,\n      \"claim\": \"Establishing that recessive MYL2 mutations cause human disease resolved whether RLC loss-of-function is tolerated: biallelic mutations disrupting the C-terminal EF-hand domain cause cardioskeletal myopathy with loss of normal RLC protein expression and myofibrillar disorganization.\",\n      \"evidence\": \"Linkage analysis, exome sequencing, and immunohistochemistry of patient skeletal muscle\",\n      \"pmids\": [\"23365102\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No in vitro reconstitution of mutant RLC function\", \"Mechanism of protein loss (degradation vs. misfolding) not determined\", \"Skeletal muscle involvement mechanism unclear\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Defining the functional consequences of MYL2 phosphorylation at Ser15 established that RLC phosphorylation directly regulates cross-bridge cycling kinetics, calcium-dependent contraction, and cardiac torsion, with a specific transmural gradient across the ventricular wall.\",\n      \"evidence\": \"Genetic mouse models with phosphorylation-site mutations, computational models, and in vitro phosphorylation assays\",\n      \"pmids\": [\"26074085\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase(s) responsible for the spatial phosphorylation gradient not fully defined in vivo\", \"Whether phosphorylation acts through SRX/DRX transitions was not yet tested\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Characterizing the DCM-associated D94A mutation in vitro revealed that a disease-causing RLC variant reduces α-helical content, impairs RLC–MHC binding and incorporation, and paradoxically increases actin-activated ATPase activity, establishing that RLC structural integrity controls myosin enzymatic function.\",\n      \"evidence\": \"Recombinant RLC expression, circular dichroism, ATPase assays, and reconstitution into RLC-depleted porcine cardiac myosin\",\n      \"pmids\": [\"25825243\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vitro ATPase increase contradicted later in vivo findings\", \"Cross-bridge structural positioning not assessed\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Analysis of the HCM-associated IVS6-1 splice site mutation demonstrated that it impairs RLC–MHC binding, slows ATP-induced acto-myosin dissociation, and increases calcium sensitivity of force, defining a shared functional signature among HCM-causing RLC mutations.\",\n      \"evidence\": \"Reconstitution of recombinant IVS6-1 RLC into depleted porcine cardiac preparations with ATPase, stopped-flow kinetics, and skinned muscle force assays\",\n      \"pmids\": [\"27378946\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No in vivo validation of this splice variant\", \"Whether this variant alters SRX/DRX balance was unknown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Transgenic D94A mice resolved a discrepancy between in vitro and in vivo ATPase effects and showed that DCM-D94A decreases calcium sensitivity and repositions cross-bridges toward the thick-filament backbone, directly linking RLC mutation to ventricular dilation and reduced ejection fraction in vivo.\",\n      \"evidence\": \"Transgenic mouse echocardiography, invasive hemodynamics, skinned fiber force-pCa, and small-angle X-ray diffraction\",\n      \"pmids\": [\"29463717\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"SRX/DRX equilibrium not directly measured\", \"How cross-bridge repositioning mechanistically causes dilation not resolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"AAV9-mediated delivery of phosphomimetic S15D-RLC rescued cardiac function in HCM-D166V mice, demonstrating that Ser15 phosphorylation is not merely correlative but causally required for normal contraction and is a viable therapeutic target.\",\n      \"evidence\": \"AAV9 gene therapy in D166V transgenic mice with echocardiography, PV loops, and skinned papillary muscle mechanics\",\n      \"pmids\": [\"31101927\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Long-term effects and potential immunogenicity not assessed\", \"Whether S15D also corrects SRX/DRX imbalance was not tested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"iPSC-derived cardiomyocytes from R58Q patients established that HCM-causing RLC mutations perturb cellular calcium handling (reduced peak transients, decreased L-type Ca²⁺ current) in addition to sarcomere mechanics, broadening the pathomechanism beyond cross-bridge cycling.\",\n      \"evidence\": \"Patient iPSC-CM model with cell size measurements, calcium imaging, and patch-clamp electrophysiology\",\n      \"pmids\": [\"30796699\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single patient line; isogenic controls not described\", \"Whether calcium channel effects are primary or secondary to sarcomere dysfunction is unclear\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Demonstrating that a recessive frameshift MYL2 variant is degraded via the proteasome while HCM missense variants are stably expressed but mislocalized clarified that distinct protein quality control fates underlie recessive vs. dominant MYL2 disease mechanisms.\",\n      \"evidence\": \"In vitro overexpression with proteasome inhibitor rescue; Drosophila Mlc2 knockdown rescue experiments\",\n      \"pmids\": [\"32453731\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Proteasome degradation shown by inhibitor rescue, not by direct ubiquitination assay\", \"Drosophila Mlc2 is not identical to human MYL2\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Simultaneous X-ray diffraction and force measurements in D166V and D94A mouse hearts unified the SRX/DRX framework for RLC mutations: HCM-D166V destabilizes SRX (shifting myosin toward DRX/actin), while DCM-D94A stabilizes SRX, providing an energetic basis for opposing cardiomyopathy phenotypes.\",\n      \"evidence\": \"Small-angle X-ray diffraction with isometric force in skinned papillary muscles; mant-ATP SRX/DRX assays\",\n      \"pmids\": [\"35177471\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether phosphorylation state modulates the SRX/DRX effect of each mutation was not tested\", \"Structural basis at atomic resolution was lacking\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identification of the GATA4→MYLK3→MYL2 phosphorylation axis as the mechanism of osimertinib-induced cardiotoxicity placed MYL2 phosphorylation regulation in a defined transcriptional signaling pathway and demonstrated reversibility upon drug withdrawal or myosin activator treatment.\",\n      \"evidence\": \"snRNA-seq, iPSC-CM assays, mouse TAC model, and pharmacological intervention with omecamtiv mecarbil\",\n      \"pmids\": [\"41330421\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Published year listed as 2026 suggesting early online; independent replication needed\", \"Whether GATA4-MYLK3 is the dominant pathway for MYL2 phosphorylation in physiological conditions is not established\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A complete atomic-resolution understanding of how individual RLC mutations alter the interacting-heads motif (IHM) and thick-filament quaternary structure in the human heart remains unresolved, as does the question of whether SRX/DRX rebalancing is a universal therapeutic target across all MYL2 cardiomyopathy variants.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No high-resolution human cardiac thick-filament structure with mutant RLC\", \"Therapeutic SRX/DRX modulation not tested for recessive loss-of-function variants\", \"In vivo role of MYL2 in NLRP3 inflammasome regulation requires independent confirmation\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 1, 4, 5]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 3, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [0, 1, 2, 5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-397014\", \"supporting_discovery_ids\": [0, 1, 2, 3, 4, 6]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [1, 2, 3, 5, 7, 8]}\n    ],\n    \"complexes\": [\n      \"cardiac myosin (hexameric thick filament complex)\"\n    ],\n    \"partners\": [\n      \"MYH7\",\n      \"MYLK3\",\n      \"GATA4\",\n      \"MYBPC3\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}