Transcriptional control of cardiac development

描述(申请人提供)：心脏是脊椎动物胚胎发育过程中第一个形成和发挥功能的器官。虽然脊椎动物心脏的形成在形态上已经得到了广泛的描述，但在分子水平上决定心肌发生谱系和控制心脏特异基因表达的调控途径还没有很好的定义。我们研究的长期目标是了解控制早期心肌决定和分化的细胞和分子机制，特别是在转录水平上。我们正在应用各种分子、细胞和遗传学方法来研究小鼠心脏的体外和体内发育。Myocardin是一种新的血清反应因子(SRF)转录辅因子，在心肌和平滑肌中特异表达。我们的假设是，myocardin是心肌和平滑肌决定和分化的关键调节因子，并且myocardin与其他转录因子在转录复合体中发挥作用，以控制心肌和平滑肌特异性靶基因的表达。这一建议的总体目标是利用肌钙蛋白作为分子工具来探索哺乳动物心脏规范的分子机制。特别是，我们将研究myocardin如何特异性反式激活心脏基因，以及myocardin在小鼠心脏发育过程中的体内功能。 其具体目的是：目的1.明确肌钙蛋白调节心肌分化和心脏特异基因激活的分子机制。目的2.鉴定我们培育的Myocardin基因零突变纯合子小鼠，并检测Myocardin在小鼠心脏发育过程中的体内作用。目的3.鉴定和鉴定与肌钙蛋白相互作用的蛋白质，作为了解肌钙蛋白依赖基因表达的转录机制的诱导性方法。这些研究应该为我们理解控制哺乳动物心脏发育的转录网络提供重要的见解。这些研究中揭示的分子策略可能适用于与病理生理相关的心脏事件，如心力衰竭和肥厚。

DESCRIPTION (provided by applicant): The heart is the first organ to be formed and function during vertebrate embryogenesis. Although the formation of vertebrate heart has been extensively described morphologically, the regulatory pathways that determine cardiomyogenic lineage and control cardiac-specific gene expression are not well-defined at the molecular level. The long-term goal of our study is to understand the cellular and molecular mechanisms that control the early cardiac muscle determination and differentiation, particularly at the transcriptional level. We are applying a variety of molecular, cellular, and genetic approaches to study mouse heart development both in vitro and in vivo. Myocardin is a novel transcriptional cofactor for serum response factor (SRF) and is specifically expressed in cardiac and smooth muscles. Our hypothesis is that myocardin is a key regulator of cardiac and smooth muscle determination and differentiation and that myocardin functions in a transcriptional complex with other transcription factors to control cardiac and smooth muscle specific target gene expression. The overall goal of this proposal is to explore the molecular mechanisms of mammalian cardiac specification using myocardin as a molecular tool. In particular, we will study how myocardin specifically transactivate cardiac genes and the in vivo function of myocardin during mouse heart development. The specific aims are: Aim 1. To define the molecular mechanisms of myocardin functions that mediate cardiac-muscle differentiation and cardiac-specific gene activation. Aim 2. To characterize mice we have generated that are homozygous for null mutation at the myocardin locus and examine the in vivo role of myocardin during mouse heart development. Aim 3. To identify and characterize proteins that interact with myocardin as an inductive approach to understand the transcriptional mechanisms of myocardin-dependent gene expression. These studies should provide an important insight into our understanding the transcriptional networks that control mammalian heart development. The molecular strategies revealed in these studies may apply to pathophysiologically related cardiac events such as cardiac failure and hypertrophy.