Raf 1-ERK cross-talk in Arteriogenesis

项目总结(见说明)： 动脉生成是在发育过程中或在成人循环中形成新的动脉血管的过程。在发育过程中，它需要形成具有动脉特征的新的内皮血管结构，其定义由关键标记物如伊弗林B2和神经粘连蛋白1的表达所定义，然后获得介质 和外膜。在成人循环中，通过扩张原有的动脉血管结构或从头开始形成新的动脉。血管内皮生长因子及其受体VEGFR2或关键的细胞内信号介质缺失会导致动脉血管发育失败。动脉生成缺陷在其他情况下可被注意到，包括eNOS缺失或疾病状态，如糖尿病和高胆固醇血症，这 失败极大地增加了与这些疾病相关的发病率和死亡率。然而，人们对整个过程知之甚少，目前还没有成功的方法来处理其在临床环境中的缺陷。了解调控动脉形成的分子机制将大有裨益。 有助于我们了解主要心血管疾病的病理生物学，并有助于开发新的治疗方法来对抗这些疾病。 在这个项目中，我们建议关注新发现的PI3K/Akt和ERK信号通路之间的相互作用，该信号通路似乎控制着动脉命运的决定。具体地说，我们将1)确定RAFL SA介导的ERK和Akt信号在发育过程中和正常血管中解偶联的生物学意义；2)确定RAFL SA介导的ERK和Akt信号解偶联在动脉形成受损环境中的生物学意义；3)剖析内皮功能障碍如何在高胆固醇血症条件下改变VEGFR2信号，并研究ERK激活是否可以缓解这一缺陷。综上所述，这组实验将提供对这一关键的决定动脉命运的信号级联的全面观察。

PROJECT SUMMARY (See instructions): Arteriogenesis is the process of formation of new arterial blood vessels during development or in the adult circulation. In development it entails formation of new endothelial vascular structures with arterial identity as defined by expression of key markers such ephrin B2 and neuropilin 1 followed by acquisition of the media and adventitia. In the adult circulation new arteries arise either by expansion of the pre-existing arterial vascular structures or de novo. Deletion of VEGF, its receptor VEGFR2 or key intracellular signaling mediators results in failure of arterial vasculature development. Defective arteriogenesis is noted in other setting including deletion of eNOS or in disease states such as diabetes and hypercholesterolemia and this failure contributes greatly to morbidity u and mortality associated with these diseases. Nevertheless, the entire process is little understood and there are no currently successful approaches to deal with its defects in clinical settings. Understanding of molecular mechanism regulating arteriogenesis would be of great benefit to our understanding of pathobiology of major cardiovascular illnesses and to development of new therapeutic approaches to combat them. In this project we propose to focus on a newly discovered interaction between PI3K/Akt and ERK signaling pathways that appears to control arterial fate determination. Specifically we will 1) establish biological significance of Rafl SA-mediated decoupling of ERK and Akt signaling during development and in the normal vasculature; 2) Determine biological significance of Rafl SA-mediated decoupling of ERK and Akt signaling in impaired arteriogenesis settings and 3) dissect how endothelial dysfunction alters VEGFR2 signaling in hypercholesterolemic conditions and study whether ERK activation mitigates this defect. Taken together, this set of experiments will provide a comprehensive look at this critical arterial fate-determining signaling cascade.