Notch signaling in cardiovascular morphogenesis

描述(由申请人提供)：这份修订后的申请侧重于Notch信号在心血管发育中的作用。已发表的和我们实验室的初步数据表明，Notch在心脏神经脊细胞中在血管平滑肌发育过程中发挥着关键的细胞自主作用，并在心脏形态发生过程中发挥额外的重要作用。内皮细胞Jagged1介导的缺口激活刺激未分化间充质细胞分化为血管间充质细胞。我们已经开始阐明的这一途径，为血管如何通过内皮细胞周围的平滑肌凝结和分化而形成提供了重要的线索。我们已经证明，这一过程中的缺陷可以导致可预见的形式的先天性心脏病，涉及心脏流出道。此外，Notch信号在第二心野的心肌祖细胞中也是必需的。未发表的数据表明，心脏前体的规范和扩张受到Notch的影响，当Notch信号被干扰时，就会出现心室性和流出道缺陷。在这项提议中，我们测试了Notch在心脏和血管形成过程中调节细胞间通讯的关键方面的假设。修改后的申请涉及的遗传杂交更少，比最初提交的申请更机械化。第三个目标已被完全取代，使我们能够测试一个详细的模型，该模型将Notch在第二个心脏领域的作用与影响心脏瓣膜和流出道形成的细胞间通信和信号通路相结合。该提案涉及以下具体目的：1)阐明Jagged1和Notch在血管发育过程中内皮-平滑肌通讯中的作用。Notch通过在锯齿状介导的Notch激活时激活Jagged1表达来调节正反馈循环的假设将得到验证。2)确定Notch在第二心野中的作用。我们将在第二心野前体细胞中执行Notch信号的获得和功能丧失。3)探讨第二心区Notch活动对心内膜垫和流出道发育的影响机制。将研究涉及Jagged1、Notch、Fgf8、Bmp4和MRTF-B的信号级联。 公共卫生相关性：拟议的工作解决了与理解心血管系统如何形成以及我们如何能够再生新的血管和新的功能心肌相关的基本问题。众所周知，Jagged1和Notch在人类心脏病中起着重要作用，因为成人和儿童心脏病都与编码这些分子的基因突变有关。

DESCRIPTION (provided by applicant): This revised application focuses on the role of Notch signaling in cardiovascular development. Published and preliminary data from our lab have demonstrated a critical, cell autonomous role for Notch in cardiac neural crest cells during vascular smooth muscle development and additional vital roles during cardiac morphogenesis. Notch activation, mediated by endothelial Jagged1, stimulates smooth muscle differentiation of undifferentiated mesenchyme fated to become vascular smooth muscle. This pathway, which we have begun to elucidate, provides important clues as to how a blood vessel forms by condensation and differentiation of smooth muscle around an endothelial tube. We have shown that defects in this process can result in predictable forms of congenital heart disease involving the outflow tract of the heart. Furthermore, Notch signaling is required in cardiomyocyte progenitors of the second heart field. Unpublished data indicates that specification and expansion of cardiac precursors are affected by Notch, and that cardiac ventricular and outflow tract defects arise when Notch signaling is perturbed. In this proposal, we test the hypothesis that Notch mediates critical aspects of cell-cell communication during cardiac and vascular formation. The revised application involves fewer genetic crosses is more mechanistic than the original submission. The third aim has been completely replaced to allow us tol test a detailed model that integrates the role of Notch in the second heart field with cell-cell communication and signaling pathways that impact cardiac valve and outflow tract formation. The proposal involves the following specific aims: 1) To elucidate the role of Jagged1 and Notch in endothelial-smooth muscle communication during vascular development. The hypothesis that Notch mediates a positive feedback loop by activating Jagged1 expression upon Jagged-mediated Notch activation will be tested. 2) To determine the role of Notch in the second heart field. We will perform both gain and loss of function for Notch signaling in second heart field progenitors. 3) To examine the mechanism by which Notch activity in the second heart field affects endocardial cushion and outflow tract development. A signaling cascade involving Jagged1, Notch, Fgf8, Bmp4 and MRTF-B will be examined. PUBLIC HEALTH RELEVANCE: The proposed work addresses fundamental questions relevant to an understanding of how the cardiovascular system forms and how we might be able to regenerate new blood vessels and new functional myocardium. The role of Jagged1 and Notch are known to be important in human cardiac disease since both adult and pediatric heart disorders are known to be associated with mutations in the genes encoding these molecules.