Histone Deacetylase Inhibition: A Novel Approach to Cardioprotection

描述（由申请人提供）：尽管有多个显著的治疗进展，但心肌梗死仍是心血管疾病的主要原因。心肌缺血/再灌注损伤仍是一个尚未解决的重要问题。组蛋白乙酰转移酶（HAT）和组蛋白脱乙酰酶（HDAC）是通过调节染色质结构来修饰基因表达的酶。它们还靶向非组蛋白蛋白，并代表生物信号传导中的一般调节机制。HDAC抑制剂已经显示出作为抗癌药物的功效，并且正在成为靶向实体和血液恶性肿瘤的令人兴奋的临床治疗。HDAC抑制钝化心脏肥大。我们的研究表明HDAC抑制剂对小鼠急性心肌缺血和心肌梗死具有保护作用。HDAC抑制导致小鼠心脏中p38和MKK 3的乙酰化和活化。我们已经确定p38在赖氨酸53和赖氨酸121位点被乙酰化。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的增加。然而，HDAC抑制保护心脏免受损伤的机制仍然未知。我们的工作假设是HDAC抑制通过激活MKK 3和p38保护心脏免受心肌损伤。我们进一步假设HDAC抑制的保护作用与预防心肌梗死后心肌重塑和增加新形成的心脏成分有关。具体目的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：我们将测量急性缺血、缺血/再灌注和慢性心肌梗死中缺血心肌中的HDAC活性。我们将研究HDAC 3，4和5蛋白及其在上述两种情况下的亚细胞分布。具体目标二：评估MKK 3、p38和Akt 1信号通路在HDAC抑制诱导的心脏保护中的作用：使用缺失MKK 3（p38的上游激活剂）、消除心脏p38和药理学抑制p38的小鼠，我们将确定MKK 3和p38的抑制是否会消除HDAC抑制的心脏保护作用。具体目标3：使用体外分析和细胞培养模型来解密p38激活的分子机制：使用已建立的体外和细胞培养模型，我们将表征p38的乙酰化，并且这种翻译后修饰将调节p38活性。具体目标4：探索HDAC抑制是否与慢性心肌梗死后的心肌修复相关。研究HDAC抑制在缺血性心脏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，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，而且还有望为缺血性心脏病和其他心血管疾病患者开发治疗策略。

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.