NUAK1 Inhibition Alleviates Ischemia-Reperfusion Injury via SYNE1-YAP1

BACKGROUND: Mechanosensitive nuclear signaling contributes to myocardial ischemia-reperfusion injury, but the substrates and mechanisms of NUAK1 (AMPK-related kinase 5) remain unclear. We investigated whether NUAK1 regulates SYNE1 (Nesprin-1)/linker of nucleoskeleton and cytoskeleton-dependent nuclear gating of YAP1 (Yes-associated protein 1) during hypoxia/reoxygenation and ischemia-reperfusion injury. METHODS AND RESULTS: Quantitative phosphoproteomics identified a conserved NUAK1-dependent phosphorylation site in striated muscle-enriched Nesprin1-α2/SYNE1 (S434; S8284 in nesprin-1 giant). Coimmunoprecipitation and in vitro kinase assays supported direct SYNE1 phosphorylation by NUAK1. In neonatal mouse ventricular myocytes, genetic or pharmacological inhibition of NUAK1 decreased apoptotic signaling, reduced SYNE1 stability, enhanced YAP1 nuclear localization, and altered nuclear YAP1 dynamics. SYNE1 phosphosite mutants and nuclear/cytoplasmic fractionation supported a NUAK1-SYNE1 axis that restrains YAP1 nuclear accumulation under stress. Atomic force microscopy linked this pathway to nuclear mechanical remodeling. In a mouse model of ischemia-reperfusion injury, NUAK1 inhibition reduced acute myocardial damage and improved remodeling indices. CONCLUSIONS: NUAK1-dependent SYNE1 phosphorylation shapes nuclear mechanosignaling during ischemic stress. NUAK1 downregulation promotes cardiomyocyte YAP1 nuclear activity and attenuates injury responses.