P1607Epigenetic modifications via histone acetylation by p300 are changed during the transition from cardiac hypertrophy to heart failure

Abstract

Background An intrinsic histone acetyltransferase (HAT), p300, is required for acetylation and the transcriptional activity of GATA4, as well as pathological left ventricular hypertrophy (LVH) and the development of heart failure (HF) in vivo. Recently, studies of histone modification have been performed within the flexible tails, such as H3K9 and H3K14. Although most previously studied histone modifications are within the flexible tails of histones, H3K122 is reportedly a novel site of the histone globular domain acetylated by p300, and its acetylation activates gene transcriptions by destabilizing histone-DNA binding and increasing the accessibility of transactional factors to DNA. However, little is known about the extent histone modifications directly affect LVH and HF. Hypothesis We hypothesized that p300 could induce epigenetic changes by acetylation of the globular domain as well as tail domain of histone during the development of LVH and HF. Methods First, to investigate whether the acetylation of H3K122 in the globular domain of histones as well as those of H3K9 and H3K14 in the tail domain of histones increased in cardiomyocytes hypertrophy, western blotting and chromatin-immunoprecipitation (ChIP) assays were performed using neonatal rat cultured cardiomyocytes with phenylephrine (PE) stimulus. Second, neonatal rat cultured cardiomyocytes were treated with p300 knockdown by siRNA or curcumin, a p300-specific HAT inhibitor. Third, to investigate the role of p300 HAT activity in histone acetylation in vivo, we utilized mice overexpressing p300 in the heart, which induced LVH. Final, to investigate whether these acetylation changes during the development of LVH and HF, in vivo ChIP assay was performed using hypertensive heart disease model of Dahl salt-sensitive rats. Results Western blotting indicated that treatment with PE increased the acetylation of H3K122 as well as those of H3K9 and H3K14 in cardiomyocytes hypertrophy. ChIP assay demonstrated that PE increased the recruitment of acetylated H3K122 and H3K9 onto ANF and BNP promoters containing the GATA element and peaks of acetylation of these domains were 4 hours after PE stimulation. Next, these acetylations were significantly inhibited by p300 knockdown by siRNA or treatment with curcumin. Conversely, in vivo ChIP assays in mice overexpressing p300 indicated that p300 overexpression increased recruitment of acetylated H3K122 and H3K9 onto ANF and BNP promoters containing the GATA element. Next, in hypertensive heart disease model of Dahl salt-sensitive rats, in vivo ChIP assays reviled that acetylation of H3K9 was increased around ANF and BNP promoters containing the GATA element at the LVH stage but that of H3K122 was increased at the HF stage. Conclusion Our data indicate that acetylation of H3K122 in globular domain of histones by p300 is the key event of the transition from LVH to HF.