Abstract 14981: Stk25 Regulates Cell Survival in Both Human and Mouse Models of Myocardial Injury

Abstract

Introduction: Dysregulation of cardiac kinases occurs in cardiovascular diseases including hypertrophy, remodeling and ischemia injury. Serine/threonine protein kinase 25 (STK25) is a stress response kinase and putative tumor suppressor that regulates cell survival and metabolism through several signaling pathways, including LATS/3HIPPO and mTOR pathways. Hypothesis: STK25 regulates cell survival, metabolism and cardiac function in human cardiomyocytes and animal injury models. Methods: CRISPR-Cas9 was used to generate a homozygous knockout (KO) of STK25 in induced pluripotent stem cell (iPSC) which were then differentiated into cardiomyocytes (iPSC-CMs). STK25 was quantified in human left ventricular tissue from heart failure (HF) patients. Stk25 KO mice were generated by CRISPR/Cas9 mediated genome engineering in C57BL/6J background. Role of STK25 in gene expression, cell proliferation/apoptosis, metabolism and cardiac function were characterized. Results: Gene set enrichment analysis (GSEA) of differential gene expression obtained by RNA-seq was used to identify upregulation of several growth and metabolism pathways in STK25KO iPSC-CMs including oxidative phosphorylation, mTORC1 signaling and myogenesis. In functional assays, STK25 modulated cell cycle progression, proliferation, hypoxia induced apoptosis, and mitochondrial respiration in iPSC-CMs. n a myocardial infarction model of cardiac injury, loss of Stk25 in vivo led to improvements in cardiac function, reduced cardiomyocyte death and diminished fibrosis. STK25 expression is increased in HF patients. Furthermore, loss of function mutations in STK25 were discovered in atrial myxomas, demonstrating STK25 altered regulation in human heart diseases. Conclusions: STK25 regulates cardiomyocyte survival in vitro and in vivo and is aberrantly regulated in both hearth failure and atrial myxomas.