Signal Transduction by alphavbeta8 Integrin

摘要 脑是哺乳动物体内血管化程度最高的器官，具有复杂的神经网络。 血管与神经元和神经胶质相互作用，形成多细胞复合体，称为神经血管复合体。 单位生长因子和细胞外基质（ECM）蛋白协同调节粘附 以及神经细胞和血管细胞之间的信号传导，以促进正常的大脑发育， physiology.这些事件在许多脑病理学中是不受管制的，包括发育 疾病如老年性基质出血和年龄相关的神经认知缺陷， 血管性痴呆令人惊讶的是，我们对调节正常的 神经-血管细胞接触和交流或这些事件在疾病期间如何出错 发病机制在这里，我们将分析ECM蛋白和它们的整合素受体在 神经血管生物学和疾病。整合素是连接ECM的a-b异二聚体蛋白质 配体的细胞骨架和控制细胞内信号级联。虽然很多事情 已知大多数整联蛋白的粘附和信号传导功能， 25年前发现整联蛋白AVB 8，其大部分仍未被研究。AVB8 在中枢神经系统（CNS）的神经胶质细胞中表达，并在以下方面起关键作用： 通过激活ECM结合的潜伏转化因子调节血管内皮细胞的行为 生长因子B（TGF B）蛋白配体。在这个更新项目中，我们将从基因上 用于分析AVB 8整联蛋白介导的 神经血管单位病理生理学中的粘附和信号传导途径。一是 表征一种新开发的敲入小鼠模型，该模型能够分离AVB 8整联蛋白 细胞外粘附来自神经-血管细胞接触中的细胞内信号传导， 通信特别是，我们将研究整合素依赖的血管形态发生， 脑和视网膜中的内皮屏障形成。其次，我们将确定 b8胞质结构域在调节整联蛋白由内而外活化和ECM亲和力/亲合力中的作用 生物化学测定和原代细胞培养模型。第三，我们将探讨旁分泌信号 血管周围神经胶质细胞中的avb 8整联蛋白与内皮细胞中的TGF β受体之间的关系。一 特别关注整合素依赖的二十二碳六烯酸（DHA）调节 CNS内皮细胞中的Mfsd 2a转运蛋白。第四，我们将探讨缺陷之间的联系， DHA代谢和BBB功能障碍的进展性神经退行性病变， 在整合素突变小鼠中发展。总之，该项目的实验将揭示新的和 整合素控制神经血管发育的重要机制， physiology.突变小鼠模型也可能提供有价值的见解途径 参与血管相关神经系统疾病的发病机制。

Abstract The brain is the most vascularized organ in the mammalian body, with its complex network of blood vessels interacting with neurons and glia in multicellular complexes termed neurovascular units. Growth factors and extracellular matrix (ECM) proteins coordinately regulate adhesion and signaling between neural cells and vascular cells to promote normal brain development and physiology. These events are deregulated in many brain pathologies, including developmental disorders such as germinal matrix hemorrhage and age-related neurocognitive deficits such as Vascular Dementia. We understand surprisingly little about mechanisms that regulate normal neural-vascular cell contact and communication or how these events go awry during disease pathogenesis. Here, we will analyze roles for ECM proteins and their integrin receptors in neurovascular biology and disease. Integrins are a-b heterodimeric proteins that link ECM ligands to the cytoskeleton and control intracellular signaling cascades. While a great deal is known about adhesion and signaling functions for most integrins, the pathways controlled by integrin avb8, which was discovered more than 25 years ago, remain largely unexplored. avb8 is expressed in glial cells of the central nervous system (CNS) and plays critical roles in regulating vascular endothelial cell behaviors via activation of ECM-bound latent-transforming growth factor b (TGFb) protein ligands. In this renewal project, we will develop genetically engineered mouse models and primary cell culture systems to analyze avb8 integrin-mediated adhesion and signaling pathways in neurovascular unit pathophysiology. First, we will characterize a newly developed knock-in mouse model that enables dissection of avb8 integrin extracellular adhesion from intracellular signaling in neural-vascular cell contact and communication. In particular, we will study integrin-dependent blood vessel morphogenesis and endothelial barrier formation in the brain and retina. Second, we will determine functions for the b8 cytoplasmic domain in regulating integrin inside-out activation and ECM affinity/avidity using biochemical assays and primary cell culture models. Third, we will explore paracrine signaling between avb8 integrin in perivascular glial cells and TGFb receptors in endothelial cells. A particular focus will be placed on integrin-dependent regulation of the docosahexaenoic (DHA) transporter Mfsd2a in CNS endothelial cells. Fourth, we will explore links between defective DHA metabolism and BBB dysfunction in the progressive neurodegenerative pathologies that develop in integrin mutant mice. In summary, experiments in this project will reveal new and important mechanisms underlying integrin control of neurovascular development and physiology. The mutant mouse models may also provide valuable insights into pathways involved in the pathogenesis of vascular-related neurological diseases.