Histone Deacetylase Inhibition: A Novel Approach to Cardioprotection

描述（由申请人提供）：心肌梗死是心血管疾病的主要原因，尽管有多项显著的治疗进展。心肌缺血/再灌注损伤仍是一个未解决的重大问题。组蛋白乙酰转移酶（Histone acetyltransferases， HAT）和组蛋白去乙酰化酶（Histone deacetylases， HDAC）是通过调节染色质结构来修饰基因表达的酶。它们也针对非组蛋白，并代表了生物信号传导的一般调节机制。HDAC抑制剂已显示出抗癌药物的功效，并正在成为针对实体和血液系统恶性肿瘤的令人兴奋的临床治疗方法。抑制HDAC抑制心肌肥厚。我们的研究表明，HDAC抑制与小鼠急性心肌缺血和心肌梗死的心脏保护有关。HDAC抑制导致小鼠心脏中p38和MKK3的乙酰化和激活。我们已经确定p38在赖氨酸53和赖氨酸121位点乙酰化。我们还证明，HDAC抑制导致慢性梗死心脏中c-kit干细胞、细胞增殖和有丝分裂增加。然而，HDAC抑制保护心脏免受损伤的机制尚不清楚。我们的工作假设是HDAC抑制通过激活MKK3和p38来保护心脏免受心肌损伤。我们进一步假设HDAC抑制的保护作用与心肌梗死后心肌重构的预防和新形成的心脏成分的增加有关。具体目标1：检测急性心肌缺血、缺血/再灌注和慢性心肌梗死中HDAC活性和HDAC 3、4和5活性：我们将测量急性心肌缺血、缺血/再灌注和慢性心肌梗死中HDAC活性。我们将在上述两种情况下检查HDAC 3、4和5蛋白及其亚细胞分布。特异性目的2：评估MKK3、p38和Akt1信号通路在HDAC抑制诱导的心脏保护中的作用：通过缺失p38上游激活因子MKK3、消除心脏p38和药理学抑制p38的小鼠，我们将确定抑制MKK3和p38是否会取消HDAC抑制的心脏保护作用。具体目标3：利用体外分析和细胞培养模型破译p38活化的分子机制：利用已建立的体外和细胞培养模型，我们将表征p38的乙酰化，以及这种翻译后修饰将调节p38的活性。特异性目的4：探讨HDAC抑制是否与慢性心肌梗死后心肌修复相关。研究HDAC抑制在缺血性心脏病中的作用不仅可以为我们对心血管生物学的理解提供新的见解，而且还可以为缺血性心脏病和其他心血管疾病患者的治疗策略提供新的见解。公共卫生相关性：该项目不仅为我们理解HDAC抑制保护缺血性心脏的新机制提供了新的见解，而且还有望开发缺血性心脏病和其他心血管疾病患者的治疗策略。

DESCRIPTION (provided by applicant): Myocardial infarction contributes a major reason for cardiovascular disease despite the multiple significant therapeutic advances. Myocardial ischemia/reperfusion injury is still a major unsolved problem. Histone acetyltransferases (HAT) and histone deacetylases (HDAC) are enzymes that modify the expression of genes by regulating chromatin structure. They also target non-histone protein and represent a general regulatory mechanism in biological signaling. HDAC inhibitors have shown efficacy as anti-cancer drugs and are emerging as exciting clinical treatments targeting solid and hematological malignancies. HDAC inhibition blunts cardiac hypertrophy. Our studies have shown that HDAC inhibition is associated with cardioprotection in acute myocardial ischemia and myocardial infarction in mouse. HDAC inhibition results in the acetylation and activation of both p38 and MKK3 in mouse hearts. We have identified that p38 is acetylated at lysine 53 and lysine 121 sites. We also demonstrated that HDAC inhibition resulted in an increase in c-kit stem cells, cell proliferation and mitosis in chronic infarcted hearts. However, the mechanism(s) by which HDAC inhibition protects the heart against injury remain unknown. Our working hypothesis is that HDAC inhibition protects the heart against myocardial injury through the activation of MKK3 and p38. We further hypothesize that the protection of HDAC inhibition is related to prevention of myocardial remodeling and an increase in newly formed cardiac components following myocardial infarction. Utilizing genetic and physiological approaches, we will test: Specific Aim 1: Examine HDAC activity and HDAC 3, 4 and 5 in acute myocardial ischemia, ischemia/reperfusion and chronic myocardial infarction: We will measure HDAC activity in ischemic myocardium in both acute ischemia, ischemia/reperfusion and chronic myocardial infarction. We will examine HDAC 3, 4 and 5 proteins and their subcellular distributions in both settings above. Specific Aim 2: Assess the roles of MKK3, p38 and Akt1 signaling pathway in the cardioprotection induced by HDAC inhibition: Using mice with deletion of MKK3, the upstream activator of p38, elimination of cardiac p38 and pharmacologic inhibition of p38, we will determine whether inhibition of MKK3 and p38 will abrogate the cardioprotective effect(s) of HDAC inhibition. Specific Aim 3: Decipher the molecular mechanism (s) of p38 activation using in vitro analysis and cell culture models: Using established the in vitro and cell culture model, we will characterize the acetylation of p38 and that such a post-translational modification will regulate p38 activity. Specific Aim 4: Explore whether HDAC inhibition is associated with myocardial repair following chronic myocardial infarction. Investigating the role of HDAC inhibition in ischemic heart could provide not only new insight into our understanding of cardiovascular biology but also development of therapeutic strategies for patients with ischemic heart disease and other cardiovascular disorders. PUBLIC HEALTH RELEVANCE: This project not only provides a new insight into our understand a novel mechanism by which HDAC inhibition protects ischemic heart, but it also holds promise to develop a therapeutic strategy for patients with ischemic heart diseases and other cardiovascular disorders.