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。这在由脑、脊髓和视网膜组成的中枢神经系统（CNS）中特别相关，其中血管生成由分泌各种生长因子和细胞外基质（ECM）蛋白的神经胶质细胞调节。然而，内皮细胞如何正确地解释神经胶质源性的线索，在很大程度上仍然是未知的。在小鼠中使用Cre/lox策略，我们发现了第一个神经胶质-内皮细胞信号传导轴，其调节发育中的CNS中的血管生成。该途径的组分包括神经胶质细胞中的α v β 8整联蛋白、ECM中其ECM结合的潜伏性转化生长因子β（TGF β）蛋白配体和内皮细胞中的典型TGF β受体（TGF β R2和Alk 5）。细胞类型特异性消融该途径中的任何组分都会导致CNS特异性血管生成缺陷和过早死亡。有趣的是，其他研究小组已经报道了神经胶质细胞中Wnt生长因子的基因缺失，或内皮细胞中Wnt信号传导效应子β-连环蛋白的基因缺失， 还导致血管生成病理学，其在很大程度上表型复制α v β 8整联蛋白和TGF β受体敲除小鼠中的那些。这些结果，以及我们在本申请中提出的未发表的机制数据，强烈支持整合素激活的TGF β和Wnt之间的串扰，在本项目中，我们将分析发育中大脑中的这些事件。特别是，一套独特的实验工具，包括小鼠和斑马鱼的遗传模型，将产生表征信号转导机制和基因调控途径的神经胶质细胞控制血管生成。我们将补充体内模型与信号实验在原代脑内皮细胞刺激Wnt和/或TGF β，并表征这些途径的组件是如何使用生物化学和基因表达谱功能互连。这些实验不仅将揭示Wnt和TGF β如何参与神经胶质细胞调节血管生成的新的重要见解，而且可能确定血管相关神经系统疾病的新的治疗机制。

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 These results, as well as unpublished mechanistic data that we present in this application, strongly support cross talk between integrin-activated TGFbetas and Wnts, and in this project we will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.