HDAC inhibition attenuates cardiac hypertrophy by acetylation and deacetylation of target genes

Pharmacological histone deacetylase (HDAC) inhibitors attenuate pathological cardiac remodeling and hypertrophic gene expression; yet, the direct histone targets remain poorly characterized. Since the inhibition of HDAC activity is associated with suppressing hypertrophy, we hypothesized histone acetylation would target genes implicated in cardiac remodeling. Trichostatin A (TSA) regulates cardiac gene expression and attenuates transverse aortic constriction (TAC) induced hypertrophy. We used chromatin immunoprecipitation (ChIP) coupled with massive parallel sequencing (ChIP-seq) to map, for the first time, genome-wide histone acetylation changes in a preclinical model of pathological cardiac hypertrophy and attenuation of pathogenesis with TSA. Pressure overload-induced cardiac hypertrophy was associated with histone acetylation of genes implicated in cardiac contraction, collagen deposition, inflammation, and extracellular matrix identified by ChIP-seq. Gene set enrichment analysis identified NF-kappa B (NF-κB) transcription factor activation with load induced hypertrophy. Increased histone acetylation was observed on the promoters of NFκB target genes (<i>Icam1, Vcam1, Il21r, Il6ra, Ticam2, Cxcl10</i>) consistent with gene activation in the hypertrophied heart. Surprisingly, TSA attenuated pressure overload-induced cardiac hypertrophy and the suppression of NFκB target genes by broad histone deacetylation. Our results suggest a mechanism for cardioprotection subject to histone deacetylation as a previously unknown target, implicating the importance of inflammation by pharmacological HDAC inhibition. The results of this study provides a framework for HDAC inhibitor function in the heart and argues the long held views of acetylation is subject to more flexibility than previously thought.

药理学组蛋白去乙酰化酶（histone deacetylase, HDAC）抑制剂可减轻病理性心脏重构与肥厚相关基因表达，但直接的组蛋白靶标仍未得到充分表征。鉴于HDAC活性抑制与肥厚进程抑制相关，我们推测组蛋白乙酰化会靶向参与心脏重构的基因。曲古抑菌素A（Trichostatin A, TSA）可调控心脏基因表达，并减轻主动脉弓缩窄（transverse aortic constriction, TAC）诱导的心肌肥厚。我们首次采用染色质免疫共沉淀（Chromatin Immunoprecipitation, ChIP）结合高通量测序（ChIP-seq），在病理性心脏肥厚的临床前模型中，绘制了TSA干预减轻发病进程后的全基因组组蛋白乙酰化变化图谱。压力负荷诱导的心肌肥厚与参与心脏收缩、胶原沉积、炎症反应及细胞外基质调控的基因的组蛋白乙酰化升高相关，该发现经ChIP-seq验证。基因集富集分析显示，负荷诱导的肥厚过程中存在核因子κB（NF-κB）转录因子的激活。在肥厚心脏中，NF-κB靶基因*Icam1、Vcam1、Il21r、Il6ra、Ticam2、Cxcl10*的启动子区域组蛋白乙酰化水平升高，与基因激活状态一致。令人意外的是，TSA可通过广泛的组蛋白去乙酰化作用，减轻压力负荷诱导的心肌肥厚并抑制NF-κB靶基因的表达。我们的研究结果揭示了一种此前未被发现的、依赖组蛋白去乙酰化的心脏保护机制，表明药理学HDAC抑制可通过调控炎症反应发挥关键作用。本研究结果为HDAC抑制剂在心脏中的作用机制提供了理论框架，并表明乙酰化调控的灵活性远超此前认知。