Genetic Models to Study Glial Regulation of Angiogenesis

描述（由申请人提供）：血管生成，或通过血管内皮细胞增殖和发芽形成新血管，对所有脊椎动物器官的发育至关重要。这在中枢神经系统（CNS）中尤其重要，中枢神经系统由脑、脊髓和视网膜组成，血管生成由分泌各种生长因子和细胞外基质（ECM）蛋白的胶质细胞调节。然而，内皮细胞如何正确地解释神经胶质来源的线索，在很大程度上仍未被描述。在小鼠中使用Cre/lox策略，我们发现了第一个调节发育中的中枢神经系统血管生成的胶质内皮细胞信号轴。该途径的组成部分包括神经胶质细胞中的α - β - 8整合素，其与ECM结合的潜伏转化生长因子β (tgf β)蛋白配体在ECM中，以及内皮细胞中的典型tgf β受体（TGFbetaR2和Alk5）。细胞类型特异性消融这一通路中的任何成分都会导致中枢神经系统特异性血管生成缺陷和过早死亡。有趣的是，其他研究小组报告了神经胶质细胞中Wnt生长因子的基因缺失，或内皮细胞中Wnt信号效应物β -连环蛋白的基因缺失，

DESCRIPTION (provided by applicant): Angiogenesis, or the formation of new blood vessels via vascular endothelial cell proliferation and sprouting, is essential for the development of all vertebrate organs. This is particularly relevant in the central nervous system (CNS), comprised of the brain, spinal cord and retina, where angiogenesis is regulated by glial cells that secrete various growth factors and extracellular matrix (ECM) proteins. How endothelial cells properly interpret glial-derived cues, however, remains largely uncharacterized. Using Cre/lox strategies in mice we have discovered the first glial-endothelial cell signaling axis that regulates angiogenesis in the developing CNS. Components of this pathway include alphavbeta8 integrin in glial cells, its ECM-bound latent transforming growth factor beta (TGFbeta) protein ligands in the ECM, and canonical TGFbeta receptors (TGFbetaR2 and Alk5) in endothelial cells. Cell type-specific ablation of any component in this pathway leads to CNS-specific angiogenesis defects and premature death. Interestingly, other groups have reported that genetic deletion of Wnt growth factors in glial cells, or the Wnt signaling effector beta-catenin in endothelial cells, also leads to angiogenesis pathologies that largely phenocopy those in alphavbeta8 integrin and TGFbeta receptor knockout mice. These results, as well as unpublished mechanistic data that we present in this application, strongly support cross talk between integrin-activated TGFbetas and Wnts, and in this project we will analyze these events in the developing brain. In particular, a unique set of experimental tools, including mouse and zebrafish genetic models, will be generated to characterize signaling mechanisms and gene regulatory pathways underlying glial control of angiogenesis. We will complement the in vivo models with signaling experiments in primary brain endothelial cells stimulated with Wnts and/or TGFbetas, and characterize how components of these pathways are functionally interconnected using biochemistry and gene expression profiling. These experiments will not only reveal new and important insights into how Wnts and TGFbetas are involved in glial regulation of angiogenesis, but may identify novel therapeutic mechanisms underlying vascular-related neurological disorders.