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，也成为我的驱动力 研究计划，表观遗传和染色质修饰在心脏过程中至关重要 的发展并将成为心脏病的重要治疗靶点。虽然数量众多 心脏发育过程中受到调节的个体基因已被描述，全球 这一过程的转录调节因子和表观遗传修饰因子尚未得到很好的表征。 组蛋白脱乙酰酶 (HDAC) 改变染色质结构并影响局部和整体基因表达 在心里和其他地方。最近，我发现小鼠体内 Hdac2 的整体缺失会导致 伴有严重心肌发育缺陷的围产期部分死亡​​。有趣的是，Hdac2 影响 心肌细胞分化与增殖之间的平衡。之前，我们已经证明了 仅同源域蛋白 (Hopx) 在胚胎和成人心脏和功能中表达，至少 部分是通过直接与 Hdac2 相互作用来介导心肌基因的抑制。全球损失 小鼠中的 Hopx 也会导致部分围产期死亡和类似于 Hdac2 的心脏缺陷 淘汰赛。在这里，我们表明 Hdac2 和 Hopx 在心脏发育和心脏丧失中共同表达 Hdac2 和 Hopx 都会导致围产期完全死亡，并伴有严重心脏缺陷，包括 肌肉性室间隔缺损和肌细胞增殖显着增加。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 无效的心。我们的机制分析表明，Hdac2 和 Hopx 的丢失会导致 Gata4 的激活，之前已被证明可以调节心肌细胞增殖。 Hdac2 相互作用 Gata4 和 Hdac2-Hopx 的缺失会增加发育中 Gata4 的乙酰化和激活 心肌。这些结果表明 Hdac2 和 Hopx 之间的相互作用在 心脏发育，因此，我将检验 Hdac2 和 Hopx 协调发挥作用的假设 在心脏中通过直接调节 Gata4 乙酰化来调节 Gata4 活性，这解释了 心肌细胞增殖的变化。具体来说，我将研究 Hdac2-Hopx 的机制 复合物在心肌细胞增殖过程中调节 Gata4 乙酰化和活性以及组织的影响 发育中的心肌中 Hdac2-Hopx 功能的特定丧失。这将通过以下方式完成 追求以下具体目标： 目标 1：确定并表征 Hdac2 和 Hopx 是否协同调节 Gata4 体外和体内的乙酰化和转录活性。 A) 表征 Hopx-Hdac2-Gata4 复合物。 B) 确定 Hdac2-Hopx 是否使 Gata4 脱乙酰。 C) 确定并表征 Hdac2-Hopx 是否调节 Gata4 转录活性。 目标 2：通过以下方式表征 Hdac2-Hopx 复合物在心脏发育中的组织特异性作用： 分析新生成的 Hdac2 floxed 等位基因。