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.

夏季 /摘要： 该提议的基本假设，以及已成为我的推动力的假设 研究计划是，心脏的表观遗传和染色质修饰至关重要 发展并将成为心脏病的重要治疗靶标。虽然很多 已经描述了在心脏发展过程中受调节的个体基因，全球 该过程的转录调节剂和表观遗传修饰符的表征较低。 组蛋白脱乙酰基酶（HDACS）修饰染色质结构并影响局部和全局基因表达 在心脏和其他地方。最近，我发现小鼠的全球HDAC2损失导致 部分围产期致死性，严重发育性心肌缺陷。有趣的是，HDAC2影响 分化与心肌细胞增殖之间的平衡。以前，我们已经表明 仅同源域蛋白（HOPX）在胚胎和成人心脏和功能中表达，至少在 在某种程度上，通过直接与HDAC2相互作用以介导抑制心肌基因。全球损失 小鼠中的Hopx还导致部分围产期致死性和类似于HDAC2的心脏缺陷 淘汰赛。在这里，我们表明HDAC2和HOPX在心发展和丧失中共同表达 HDAC2和HOPX都会导致完全围产期致死性，严重的心脏缺陷包括 肌肉心室间隔缺陷，明显增加了肌细胞增殖。微阵列分析 揭示了HDAC2-中几个细胞周期特异性基因以及心脏结构基因的失调 Hopx-null心。我们的机械分析表明，HDAC2和HOPX的损失导致 GATA4的激活，先前已显示以调节心肌细胞增殖。 HDAC2相互作用 随着GATA4和HDAC2-HOPX的损失，在发育中增加了GATA4乙酰化和激活 心肌。这些结果表明，HDAC2和HOPX之间的相互作用在 心脏发展，因此，我将测试HDAC2和HOPX协调起作用的假设 在心脏中，通过直接调节GATA4乙酰化来调节GATA4活性，这说明了 心肌细胞增殖的变化。具体而言，我将研究HDAC2-HOPX的机制 复合物调节在心肌增殖过程中的GATA4乙酰化和活性以及组织的作用 发育中的心肌中HDAC2-HOPX功能的特异性损失。这将通过 追求以下具体目标： AIM 1：确定并表征HDAC2和HOPX是否协调函数以调节GATA4 乙酰化和体内的转录活性。 a）表征Hopx-HDAC2-GATA4复合物。 b）确定HDAC2-HOPX脱乙酰基GATA4是否。 c）确定并表征HDAC2-HOPX是否调节GATA4转录活性。 目标2：表征HDAC2-HOPX复合物在心脏发育中的组织特异性 对新产生的HDAC2等位基因的分析。