{"database":"GEO","file_versions":[{"headers":{"Content-Type":["application/json"]},"body":{"files":{"Other":["ftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE333nnn/GSE333349/"]},"type":"primary"},"statusCode":"OK","statusCodeValue":200}],"scores":null,"additional":{"omics_type":["Transcriptomics"],"species":["Danio rerio"],"gds_type":["Expression profiling by high throughput sequencing"],"full_dataset_link":["https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE333349"],"repository":["GEO"],"entry_type":["GSE"],"additional_accession":[]},"is_claimable":false,"name":"Beyond Glycogen Storage: AMPKγ2 Regulates Cardiac Hypertrophy and Electrophysiology via Myosin Interaction","description":"Introduction: Variants in PRKAG2 cause hypertrophic cardiomyopathy (HCM) and conduction disturbances. While prior studies associated PRKAG2-related hypertrophy with increased glycogen storage, many HCM phenotypes remain unexplained. We aimed to uncover how PRKAG2 variants induce myocyte hypertrophy and electrical changes during early cardiac development. Methods: We generated transgenic zebrafish expressing wild-type (TgWT) or pathogenic variant (TgR299Q) Prkag2 cDNA under a myocardium-specific promoter, and examined cardiac electrophysiology, contractile function, and cytoarchitecture during cardiogenesis and in adult hearts. Results: TgR299Q fish showed hypertrophic cardiomyocytes and progressive contractile abnormalities, recapitulating human HCM phenotypes. Cardiomyocyte glycogen was elevated in adult but not embryonic hearts. Despite the absence of glycogen accumulation at 6-day post-fertilization, TgR299Q hearts showed electrical abnormalities, including reduced conduction velocity and prolonged action potential and Ca2+ transient durations. We observed decreased AMPK phosphorylation in the TgR299Q hearts. However, AMPK activation did not rescue the electrophysiological abnormalities in TgR299Q. Proximity ligation assays and co-immunoprecipitation identified a physical interaction between AMPKγ2 and myosin, enhanced by the R299Q variant and accompanied by increased AMPKγ2 localization to the myofilament. Na+/Ca2+ exchanger (NCX) inhibition increased Ca2+ duration and diastolic Ca2+ in TgWT but not TgR299Q hearts, indicating reduced free cytosolic Ca2+ for NCX-mediated extrusion in TgR299Q. These findings suggest that enhanced AMPKγ2-myosin interaction may promote myofilament Ca2+ retention, thereby prolonging Ca2+ transient duration and APD in the mutant. Notably, the myosin inhibitor mavacamten reduced AMPKγ2-myosin interaction in TgR299Q hearts, and both mavacamten and vmhcl knockdown rescued the early electrophysiological abnormalities. Conclusions: The PRKAG2 variant altered cardiac excitability, contractility, and Ca2+ handling during cardiogenesis, independent of glycogen accumulation. Enhanced interactions between AMPKγ2 and myosin contributed to these early changes. Our study revealed a novel link between cellular energy sensing and contractile machinery, with therapeutic potential for modulating contractile function in cardiomyopathies.","dates":{"publication":"2026/05/26"},"accession":"GSE333349","cross_references":{"GSM":["GSM9761264","GSM9761265","GSM9761273","GSM9761262","GSM9761263","GSM9761271","GSM9761272","GSM9761270","GSM9761268","GSM9761269","GSM9761266","GSM9761267"],"GPL":["23085"],"GSE":["333349"],"taxon":["Danio rerio"]}}