TRANSCRIPTIONAL REGULATION OF CARDIOMYOCYTE DEVELOPMENT

描述（改编自申请人的摘要）： 了解了调节分化的分子机制， 在哺乳动物发育过程中的骨骼肌谱系。在 相比之下，目前对分子碱基的了解相对较少 心肌细胞的分化。最近的研究表明 不同的转录途径调节骨骼和心脏- 特异性基因表达和分化。然而，直到最近， 重要的转录因子的身份， 心脏特异性基因表达仍不清楚。成员 加塔家族的锌指转录因子已被证明发挥作用 在多种造血细胞分化中的重要作用 血统申请人和其他人最近的证据表明， 这个家族的新成员加塔-4在 心脏特异性基因表达的协调调节 发展加塔-4表达局限于心前中胚层 以及小鼠早期胚胎心管折叠。此外，加塔-4 表达比心肌收缩蛋白早0.5-1天 在小鼠胚胎发育过程中。最重要的是，加塔-4结合于 多个心脏基因的启动子-增强子元件，包括 心肌肌钙蛋白C和肌钙蛋白T基因，ANF基因，肌球蛋白轻链， 链1基因和α-MHC基因。此外，被迫表达 加塔-4的表达可以直接反式激活至少一些 这些心脏特异性的启动子-增强子在非肌肉细胞中。采取 总之，这些研究与加塔-4的假设一致， 是重要的心肌细胞决定基因之一。研究 在本申请中描述的是（i）映射重要的 加塔-4转录因子的功能结构域，（ii）直接测试 加塔-4在调节心脏基因表达中的作用， 心肌细胞分化的影响，通过研究靶向 加塔-4基因对体外培养心肌细胞发育的影响 （iii）绘制加塔-4的区域，所述区域是 体外培养心肌细胞分化及基因表达 胚胎干细胞向胚状体的分化。

DESCRIPTION (adapted from the applicant's abstract): Much has been learned about the molecular mechanisms that regulate the differentiation of the skeletal muscle lineages during mammalian development. In contrast, relatively little is currently understood about molecular bases of cardiac myocyte differentiation. Recent studies have demonstrated that distinct transcriptional pathways regulate skeletal and cardiac- specific gene expression and differentiation. However, until recently, the identity of the important transcription factors that regulate cardiac-specific gene expression have remained unclear. Members of the GATA family of zinc finger transcription factors have been shown to play important roles in the differentiation of multiple hematopoietic lineages. Recent evidence from the applicant and others suggests an important role for a new member of this family, GATA-4, in the coordinate regulation of cardiac-specific gene expression during heart development. GATA-4 expression is restricted to the pre-cardiac mesoderm and folding heart tube in the early mouse embryo. Moreover, GATA-4 expression precedes that of the cardiac contractile proteins by 0.5-1 day during mouse embryogenesis. Most importantly, GATA-4 binds to the promoter-enhancer elements of multiple cardiac genes, including the cardiac troponin C and troponin T genes, the ANF gene, the myosin light chain 1 gene, and the alpha-MHC gene. In addition, the forced expression of GATA-4 can directly transactivate the expression of at least some of these cardiac- specific promoter-enhancers in non-muscle cells. Taken together, these studies are consistent with the hypothesis that GATA-4 is one of the important cardiac myocyte determining genes. The studies described in this application are intended to (i) map the important functional domains of the GATA-4 transcription factor, (ii) directly test the role of GATA-4 in the regulation of cardiac gene expression and cardiac myocyte differentiation by studying the effects of targeted disruptions of the GATA-4 gene on cardiac myocyte development in vitro and in vivo, and (iii) map the regions of GATA-4 that are necessary for cardiac myocyte differentiation and gene expression during the in vitro differentiation of ES cells into embryoid bodies.