REGULATION OF ATRIOVENTRICULAR CANAL MESENCHYME FORMATION

胚胎心脏房室管的发育 以血管内皮细胞-间充质细胞转化为特征 内皮细胞亚群。这些细胞改变表型成为 侵袭性间充质细胞，是瓣膜和 心脏中的间隔结构。通过使用胶原胶培养物 胚胎鸡的材料，我们和其他人展示了转化 这一过程是由来自心肌的信号刺激的，并且既是 在地区和时间上都是特定的。初步研究发现了一种 生长因子，转化生长因子β，作为转化过程的一个组成部分。 在之前的赠款期间，我们展示了TGFbeta3，在 TGFbeta家族，在心脏内有适当的分布。 此外，通过处理心脏外植体可以降低TGFbeta3的mRNA水平 修饰的反义寡核苷酸证实了它的直接作用 鸟类心脏中的分子。我们还鉴定了一种可能 与心脏内的TGFbeta3编码转录本杂交。这 反义RNA的分布和外观与在 规范TGFbeta3消息转换。进行了更多的研究 要开始解决细胞转化的过程，首先要确定 靶血管内皮细胞的信号转导和基因表达。 在此建议继续研究，以探索细胞转化在 心脏和TGFbeta3在这一过程中的调节。的具体目标 建议是：L)分析TGFbeta3信息和蛋白质生产 在缓冲组织形成过程中。2)反义TGFbeta3mRNA的鉴定 在心脏中，如果合适的话，还有它的蛋白质产物。3)描述 调节反义TGFbeta3转录的激活信号。4) 检测信号转导分子和其他分子的表达 在此SCOR中确定的分子可以直接与 胚胎心脏的瓣膜形成或相关的形态发生过程。 这些研究将确定TGFbeta3的作用及其在 心脏瓣膜和间隔间充质的鉴别。的目标是 这项工作是为了理解这一过程中涉及的分子信号 诱导的表型变化。对这些过程的理解将 提供基本的发育原理和确定候选基因 以及与先天性心脏病有关的相互作用。

Development in the atrioventricular canal of the embryonic heart is characterized by an endothelial-mesenchymal cell transformation of a subpopulation of endothelial cells. These cells change phenotype to become invasive mesenchymal cells and are the earliest progenitors of valve and septal structures in the heart. Through use of collagen gel cultures of embryonic chicken material, we and others showed that the transformation process is stimulated by a signal from the myocardium and is both regionally and temporally specific. Preliminary studies had identified a growth factor, TGFbeta, as a component of the transformation process. During the previous grant period we showed TGFbeta3, among the members of the TGFbeta family, to have an appropriate distribution within the heart. Further, reduction of TGFbeta3 mRNA levels by treating heart explants with modified antisense oligonucleotides confirmed a direct role for this molecule in the avian heart. We have also identified an mRNA that may hybridize to TGFbeta3 encoding transcripts within the heart. This antisense RNA has a distribution and appearance consistent with a role in regulating TGFbeta3 message translation. Additional studies were performed to begin to address the process of cell transformation by identifying signal transduction and gene expression in the target endothelial tissue. Continuing studies are proposed here to explore cell transformation in the heart and the regulation of TGFbeta3 in this process. The specific aims of the proposal are to: l) Analyze TGFbeta3 message and protein production during cushion tissue formation. 2) Characterize antisense TGFbeta3 mRNA in the heart and, if appropriate, its protein product. 3) Characterize the activation signals which regulate antisense TGFbeta3 transcription. 4) Examine expression of signal transduction molecules and additional molecules identified within this SCOR which can be directly related to valve formation or related morphogenetic processes in the embryonic heart. These studies will define the role of TGFbeta3 and its regulation in the differentiation of cardiac valvular and septal mesenchyme. The goal of this work is to understand the molecular signals involved in this process of induced phenotypic change. An understanding of these processes will provide both basic developmental principles and identify candidate genes and interactions involved in congenital heart disease.