Abstract 355: Post-translational Modification of Histone Variants in Cardiac Hypertrophy

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While global changes in gene expression are a hallmark of cardiac hypertrophy, much less is known regarding the epigenetic factors driving these changes. Local chromatin packing and gene accessibility, which governs transcriptional status, has been correlated with specific post-translational modifications on the histone tails of nucleosomes occupying these regions. However, the specific alterations in histone post-translational modifications driving gene expression changes during cardiac hypertrophy are largely unknown. To identify myocyte specific changes in histone post-translational modifications during cardiac hypertrophy we performed label-free quantitation of nuclear proteins from isolated neonatal rat ventricular myocytes exposed to the hypertrophic agonists, phenylephrine and isoproterenol. Peptide samples were analyzed on a Thermo Orbitrap Velos Pro mass spectrometer using CID & HCD fragmentation. Differential expression analysis was performed using the Progenesis LC-MS software where modified histone peptides were normalized against total protein expression. We observed multiple known and novel post-translational modifications on each of the four core histones, many of which changed in the setting of hypertrophy. To validate these findings in an animal model we performed the same analysis of histone post-translational modifications from cardiac tissue of mice under basal conditions or after pressure-overload induced hypertrophy. This study provides the first global characterization of myocyte specific changes in histone post-translational modifications in cardiac hypertrophy and highlight basic mechanisms of genomic reprogramming operative in disease.

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