Signal Transduction by alphavbeta8 Integrin

摘要 大脑是哺乳动物体内血管最丰富的器官，其复杂的 多细胞复合体中与神经元和胶质细胞相互作用的血管称为神经血管 单位。生长因子和细胞外基质(ECM)蛋白协同调节黏附 神经细胞和血管细胞之间的信号传递，以促进正常的大脑发育和 生理学。这些事件在许多大脑病理中被解除调控，包括发育 生发基质出血等疾病和年龄相关的神经认知缺陷，如 血管性痴呆。令人惊讶的是，我们对调节正常的机制知之甚少 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，我们将分析细胞外基质蛋白及其整合素受体在 神经血管生物学与疾病。整合素是连接细胞外基质的a-b异二聚体蛋白。 配体连接到细胞骨架，并控制细胞内的信号级联。虽然很大一部分是 已知大多数整合素的黏附和信号功能，这些通路由 整合素avb8是在25年前发现的，目前在很大程度上仍未被探索。AVB8 在中枢神经系统(CNS)的神经胶质细胞中表达，并在 激活细胞外基质结合潜伏转化调控血管内皮细胞行为 生长因子b(TGFb)蛋白配体。在这个更新项目中，我们将从基因上发展 用于分析avb8整合素介导的转基因小鼠模型和原代细胞培养系统 神经血管单位病理生理学中的黏附和信号通路。首先，我们将 描述一种新开发的能够解剖avb8整合素的敲入小鼠模型 神经-血管细胞接触中细胞内信号转导的细胞外黏附 沟通。特别是，我们将研究整合素依赖的血管形态发生和 在大脑和视网膜中形成内皮屏障。第二，我们将确定 B8胞质结构域调节整合素内向外激活和细胞外基质亲和力 生化分析和原代细胞培养模型。第三，我们将探索旁分泌信号 血管周围神经胶质细胞中的avb8整合素与内皮细胞中的TGFb受体之间的关系。一个 重点将放在整合素对二十二碳六烯酸(DHA)的依赖调节上。 中枢神经系统内皮细胞的转运蛋白Mfsd2a。第四，我们将探索缺陷之间的联系 进行性神经退行性病变中的DHA代谢和BBB功能障碍 发展成整合素突变小鼠。总而言之，本项目中的实验将揭示新的和 整合素调控神经血管发育的重要机制 生理学。突变小鼠模型也可能提供对通路的有价值的见解。 参与血管相关神经疾病的发病机制。

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.