The Role of HDAC3 in Cardiac Growth and Development

描述（申请人提供）：心脏的发育过程包括细胞分化和增殖，导致成熟心脏的形成。心脏发育异常导致先天性心脏病，这是人类最常见的出生缺陷形式。更具体地说，影响心脏生长的通路中断可能是先天性左心或右心发育不全儿童的潜在病因。了解心脏发生过程中信号通路控制增殖的心肌特异性分子机制是心脏发育和疾病的核心问题。这些途径是复杂的，在许多情况下涉及转录因子和细胞周期调节因子。共价染色质修饰在转录调控和细胞周期进程中起着关键作用，因此预计也会影响心脏的这些过程。在这些修饰中，组蛋白乙酰转移酶（HATs）的乙酰化和组蛋白去乙酰化酶（hdac）的逆转被研究得最多，并被认为是调节这些过程的关键事件。小鼠和斑马鱼模型的实验数据表明，HDAC家族I类成员HDAC1在胚胎心脏生长发育中起重要作用。然而，其他I类hdac在心脏生长发育中的作用尚不清楚。作为首席研究员对胚胎心肌生长和发育兴趣的延伸，他发起了对HDAC1以外的I类hdac的作用的全面分析。初步研究表明，HDAC3（一类成员）在心脏生长和发育中都起着重要作用。在这项初步研究中，研究人员提出了一些实验，以深入了解HDAC3在胚胎心脏生长和发育中的作用。他们将追求两个目标：特异性目标1将确定hdac3缺乏对斑马鱼胚胎心脏的影响。研究人员将通过用morpholino反义寡核苷酸破坏hdac3的功能，产生hdac3缺陷的斑马鱼胚胎，并将其与hdac3突变体进行比较，来解决这个问题。hdac3缺陷胚胎将通过形态学和功能分析进行评估，特别强调心脏。通过分子标记、细胞计数测定、细胞凋亡和增殖试验来评估心脏的分化，从而完成心脏的鉴定。特异性目标2将确定hdac3缺陷胚胎由于心肌细胞内hdac3功能的丧失或由于对其他支持组织细胞功能的影响而导致的心脏缺陷是什么？研究人员将通过对照和hdac3缺陷胚胎之间的相互细胞移植来解决这个问题。他们还将使用选定的分子标记来解剖与心脏发育相关的心外过程，这些过程在hdac3缺陷胚胎中可能受到影响。

DESCRIPTION (provided by applicant): The process of cardiac development incorporates cell differentiation and proliferation, which lead to the formation of the mature heart. Abnormalities in cardiac development result in congenital heart diseases, which is the most frequent form of birth defects in humans. More specifically, disruption of pathways affecting cardiac growth could be the underlying etiology in a subset of children born with hypoplastic left or right heart. Understanding the myocardial-specific molecular mechanisms by which signaling pathways control proliferation during cardiogenesis is a central issue in cardiac development and disease. These pathways are complex, and in many cases implicate transcription factors and cell cycle regulators. Covalent chromatin modifications play a critical role in transcriptional regulation and cell cycle progression, and therefore are expected to affect theses processes in the heart as well. Of these modifications, acetylation by histone acetyltransferases (HATs) and its reversal by histone deacetylases (HDACs) have been most studied and appreciated as a key event in regulating these processes. Experimental data from the mouse and zebrafish models suggest that HDAC1, a class I HDAC family member, plays an important role in embryonic cardiac growth and development. However, the role of other class I HDACs in cardiac growth and development remains unknown. As an extension of the principal investigator's interest in embryonic myocardial growth and development, he initiated a comprehensive analysis of the role of class I HDACs other than HDAC1. Preliminary studies suggest an important role for HDAC3, a class I member, both in cardiac growth and in development. In this pilot study, the investigators propose experiments that will offer insights into the role of HDAC3 in embryonic cardiac growth and development. They will pursue two aims: Specific Aim 1 will determine the effect of hdac3 deficiency in the zebrafish embryonic heart. The investigators will address this question by generating hdac3-deficient zebrafish embryos by disrupting hdac3 function with morpholino antisense oligonucleotides and comparing them with hdac3 mutants. The hdac3 deficient embryos will be evaluated by morphological and functional analysis with particular emphasis on the heart. Heart characterization will be completed by assessment of differentiation by the use of molecular markers, cell count determination, apoptosis, and proliferation assays. Specific Aim 2 will determine what are the cardiac defects in the hdac3 deficient embryos due to the loss of hdac3 function within cardiomyocytes or due to effects upon cellular functions in other support tissues? The investigators will address this question by reciprocal cell transplantations between control and hdac3-deficient embryos. They will also use selected molecular markers to dissect extracardiac processes relevant to cardiac development that are potentially affected in the hdac3 deficient embryos.