Abstract 10039: Cardiomyocyte N-myristoylation Plays an Essential Role During the Development of Heart Failure

Abstract

Background: N-myristoylation is co- and post-translational modifications of proteins, which involve attachment of myristic acid to the N-terminal glycine. Although N-myristoylation plays important roles in physiological activities such as intracellular signaling, the precise regulation and functional relevance of N-myristoylation in the heart remain to be elucidated. Methods and Results: We applied a click chemistry-based approach to determine the global N-myristoylated protein profiling in the cardiomyocyte. Proteomics analysis identified 41 and 34 N-myristoylated proteins in H9c2 myocytes and neonatal rat cardiomyocytes, and 66.1% of them were discovered for the first time at endogenous levels. The levels of N-myristoylation were significantly decreased by the N-myristoyltransferase (NMT) 2 inhibition with siRNA or adenoviral shRNA knockdown, but not by the NMT1 inhibition. In response to angiotensin II (AII), N-myristoylated levels were differentially altered, and MARCKS was identified as the most down-regulated N-myristoylated protein. Wild-type MARCKS was localized to the cellular membrane, while the mutant MARKS with replacement of N-terminal glycine to alanine (G2A), which lacked the capacity of N-myristoylation, exhibited cytosolic distribution. Cardiomyocyte hypertrophy was exacerbated in mutant G2A MARCKS accompanied by increased levels of histone acetylation and phosphorylation of HDAC4 and CaMKII after AII. Gene transfer delivering NMT2 gene specific to the heart using adeno-associated virus 9 significantly improved pressure overload-induced left ventricular systolic dysfunction, cardiac hypertrophy, and myocardial fibrosis, associated with decreased levels of histone acetylation after the transverse aortic constriction in mice ( Fig ). Conclusion: Cardiomyocyte N-myristoylation plays an essential role in developing heart failure, and its modification by NMT2 may be a novel therapeutic strategy for heart failure.