Function of GATA Factors in Cardiogenesis

描述（由申请人提供）：转录因子GATA-4/5/6亚家族调节心脏发生的各个方面，从细胞规范到心管形态发生和瓣膜形成。这一提议的假设是GATA-4/5/6基因参与了一个组合代码，该组合代码在心脏发生的多个步骤中定义了细胞和形态表型。确定每个基因对心脏发生的相对贡献，以及它们的相对表达模式是如何通过上游调控程序建立的，将是很重要的。需要创新的动物模型来克服当前进展的局限性。我们建议利用爪蟾胚胎和转基因斑马鱼的新品系来了解GATA因子在心脏发育过程中的功能和调控。以下目的将测试控制GATA-4/5/6的功能特异性和调节机制：

DESCRIPTION (provided by applicant): The GATA-4/5/6 subfamily of transcription factors regulates various aspects of cardiogenesis, from cell specification through heart tube morphogenesis and valve formation. The hypothesis of this proposal is that the GATA-4/5/6 genes contribute to a combinatorial code that defines cellular and morphological phenotypes during multiple steps of cardiogenesis. It will be important to determine the relative contribution of each gene to cardiogenesis, and how their relative expression patterns are established by upstream regulatory programs. Innovative animal models are needed to overcome limitations to current progress. We propose to use Xenopus embryos and novel lines of transgenic zebrafish to understand the function and regulation of GATA factors during heart development. The following aims will test the specificity of function and regulatory mechanisms controlling GATA-4/5/6: 1. Define the specificity of function for GATA-4/5/6 during early cardiogenesis. The Xenopus system will be exploited to effectively inhibit expression of each gene alone or in combination, within specific germ layers of embryos, and during specific induction assays in explants. 2. Define the role of regulatory factors to establish and maintain the GATA-4 cardiogenic expression pattern. Novel lines of transgenic zebrafish were generated that express GFP under the control of GATA-4 regulatory sequences. Using a reverse genetic approach the transgenic system will be used to define the cis-elements that are required to target expression to specific domains of the normal GATA-4 pattem, and the role of T-box factors will be further investigated since T-box binding sites regulate activity of an already identified upstream enhancer. 3. Identify novel regulatory pathways that control expression of GATA-4 and GATA-6. The expression patterns for these key regulatory genes are overlapping but distinct and are likely therefore to be controlled by some common pathways, but also some that arc specific. Candidate pathways will be tested in the context of our reporter fish and a forward genetic screen will be used to identify genes that control expression of GATA-4, GATA-6, or both.