Hdac2 and Hopx: Regulators of Cardiac Development

Hdac2 和 Hopx：心脏发育的调节因子

• 批准号: 8316199
• 负责人: Chinmay M Trivedi
• 金额: $ 24.9万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-10 至 2014-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8316199
• 关键词: Accounting; Acetylation; Adult; Affect; Alleles; Cardiac; Cardiac Myocytes; Cell Cycle; Chromatin Structure; Complex; Congenital Heart Defects; Defect; Development; Embryo; Epigenetic Process; Equilibrium; Gene Expression; Genes; Heart; Heart Diseases; Histones; Human; Individual; Knock-out; Mediating; Microarray Analysis; Mus; Muscle; Muscle Cells; Myocardial; Myocardium; Perinatal; Process; Proteins; Repression; Research; Role; Structural Genes; Testing; Tissues; Ventricular Septal Defects; abstracting; cardiogenesis; chromatin modification; congenital heart disorder; driving force; heart function; homeodomain; in vitro activity; in vivo; programs; research study; therapeutic target

Project Summery / Abstract: The underlying hypothesis of this proposal, and one that has become the driving force of my research program, is that epigenetic and chromatin modifications are critical during cardiac development and will emerge as important therapeutic targets for cardiac diseases. While numerous individual genes that are regulated during cardiac development have been described, global transcriptional regulators and epigenetic modifiers of this process have been less well characterized. Histone deacetylases (HDACs) modify chromatin structure and affect local and global gene expression in the heart and elsewhere. Recently, I have discovered that global loss of Hdac2 in mice results in a partial perinatal lethality with severe developmental myocardial defects. Interestingly, Hdac2 affects the balance between differentiation and proliferation of cardiomyocytes. Previously, we have shown that Homeodomain only protein (Hopx) is expressed in the embryonic and adult heart and functions, at least in part, by directly interacting with Hdac2 to mediate the repression of myocardial genes. Global loss of Hopx in mice also results in a partial perinatal lethality and cardiac defects that resemble Hdac2 knockouts. Here, we show that Hdac2 and Hopx are co-expressed in the developing heart and loss of both Hdac2 and Hopx results in complete perinatal lethality with severe cardiac defects including muscular ventricular septal defects and markedly increased myocyte proliferation. Microarray analysis reveals dysregulation of several cell-cycle specific genes as well as cardiac structural genes in Hdac2- Hopx-null hearts. Our mechanistic analysis indicates that loss of both Hdac2 and Hopx leads to activation of Gata4, which has been shown previously to regulate myocyte proliferation. Hdac2 interacts with Gata4 and loss of Hdac2-Hopx increases Gata4 acetylation and activation in developing myocardium. These results suggest that the interaction between Hdac2 and Hopx is functional during cardiac development and therefore, I will test the hypothesis that Hdac2 and Hopx coordinately function in the heart to regulate Gata4 activity by directly regulating Gata4 acetylation and that this accounts for changes in myocyte proliferation. Specifically, I will investigate the mechanism by which Hdac2-Hopx complex regulates Gata4 acetylation and activity during myocyte proliferation and the effects of tissue specific loss of Hdac2-Hopx function in the developing myocardium. This will be accomplished by pursuing the following specific aims: Aim 1: Determine and characterize whether Hdac2 and Hopx function coordinately to regulate Gata4 acetylation and transcriptional activity in vitro and in vivo. A) Characterize the Hopx-Hdac2-Gata4 complex. B) Determine whether Hdac2-Hopx deacetylates Gata4. C) Determine and characterize whether Hdac2-Hopx regulates Gata4 transcriptional activity. Aim 2: Characterize the tissue specific role of Hdac2-Hopx complex in cardiac development through analysis of a newly generated floxed allele of Hdac2.

项目总结/摘要： 这一提议的基本假设，也是我的动力之一， 表观遗传和染色质修饰在心脏病的发生中至关重要， 发展，并将成为心脏疾病的重要治疗靶点。虽然许多 已经描述了在心脏发育过程中受到调控的单个基因， 该过程的转录调节因子和表观遗传修饰因子的特征还不太清楚。 组蛋白去乙酰化酶（HDAC）修饰染色质结构并影响局部和整体基因表达 在心脏和其他地方。最近，我发现小鼠体内Hdac 2的整体缺失导致了一种新的免疫缺陷。 部分围产期死亡，伴有严重的发育性心肌缺陷。有趣的是，Hdac 2影响了 平衡心肌细胞的分化和增殖。之前，我们已经证明， 同源结构域蛋白（Homeodomain only protein，Hopx）在胚胎和成人心脏中表达，至少在 部分通过直接与Hdac 2相互作用介导心肌基因的抑制。全球损失了 小鼠中的Hopx也导致部分围产期死亡和类似于Hdac 2的心脏缺陷。 击倒对手。在这里，我们发现Hdac 2和Hopx在发育中的心脏中共同表达，而Hdac 2和Hopx在发育中的心脏中共同表达。 Hdac 2和Hopx均导致围产期完全死亡，伴有严重的心脏缺陷，包括 肌性室间隔缺损和显著增加的肌细胞增殖。微阵列分析 揭示了Hdac 2-中几个细胞周期特异性基因以及心脏结构基因的失调 无肝细胞心脏我们的机理分析表明，Hdac 2和Hopx的丢失导致 Gata 4的激活，其先前已显示调节肌细胞增殖。HDAC 2相互作用 与Gata 4和Hdac 2-Hopx的损失增加了Gata 4乙酰化和活化， 心肌这些结果表明，Hdac 2和Hopx之间的相互作用在细胞凋亡过程中是功能性的。 因此，我将检验Hdac 2和Hopx协调功能的假设 在心脏中通过直接调节Gata 4乙酰化来调节Gata 4活性，这解释了 肌细胞增殖的变化。具体来说，我将研究Hdac 2-Hopx 复合物调节Gata 4乙酰化和活性在肌细胞增殖和组织的影响 在发育心肌中Hdac 2-Hopx功能的特异性丧失。这将通过 具体目标如下： 目的1：确定和表征Hdac 2和Hopx是否协调调节Gata 4 乙酰化和体外和体内转录活性。 A）表征Hopx-Hdac 2-Gata 4复合物。 B）确定Hdac 2-Hopx是否使Gata 4脱乙酰。 C）确定和表征Hdac 2-Hopx是否调节Gata 4转录活性。 目的2：通过以下方法表征Hdac 2-Hopx复合物在心脏发育中的组织特异性作用： 分析新产生的Hdac 2的floxed等位基因。