Signal Transduction by alphaVbeta8 Integrin

描述(申请人提供)：细胞是信息管理机器，必须解释细胞外线索的环境，以控制从增殖到分化和迁移的输出。整合素是连接细胞外基质(ECM)和细胞骨架并控制细胞内信号转导的异源二聚体蛋白。虽然对大多数整合素的黏附和信号转导功能有很多了解，但20多年前发现的整合素avb8调控的信号转导通路在很大程度上仍未被探索。Avb8整合素包含几个新的特征，这些特征表明了独特的信号功能。例如，b8细胞质尾部的初级氨基酸序列与其他整合素不同，表明与非典型信号效应器相互作用。此外，B8整合素缺乏细胞外的“死栓”结构域，而在其他整合素中，该结构域调节由内而外的激活，这表明ECM亲和力调节机制不同。PI的团队已经进行了遗传筛选和基于蛋白质组的实验，以确定与b8整合素结合但不与其他整合素亚基结合的细胞内信号效应器。在这个项目中，我们将使用基因工程小鼠模型和原代培养系统来分析这些效应蛋白如何对avb8整合素介导的细胞迁移做出贡献。在目标1中，我们将描述Avb8整合素、细胞质酪氨酸磷酸酶PTP-PEST和Rho GTP酶效应蛋白RhoGDI1之间的联系。目的2分析Avb8整合素与细胞骨架支架蛋白和丝氨酸/苏氨酸蛋白磷酸酶1(PP1)调节亚基SPIN之间的功能相互作用。最后，我们将探讨SPINOPILIN/PP1、PTP-PEST和Rho信号之间的整合素依赖的联系。综上所述，本项目的实验将揭示avb8整合素在发育和疾病过程中控制细胞黏附和迁移的新的重要机制。

DESCRIPTION (provided by applicant): Cells are information management machines that must interpret a milieu of extracellular cues to control outputs ranging from proliferation to differentiation and migration. Integrins are ab heterodimeric proteins that link the extracellular matrix (ECM) to the cytoskeleton and control intracellular signaling cascades. While a great deal is known about adhesion and signaling functions for most integrins, signal transduction pathways regulated by integrin avb8, which was discovered more than 20 years ago, remain largely unexplored. avb8 integrin contains several novel features that suggest unique signaling functions. For example, the primary amino acid sequence of the b8 cytoplasmic tail is divergent from other integrins, suggesting interactions with atypical signaling effectors. In addition, b8 integrin lacks an extracellular "deadbolt" domain that in other integrins modulates inside-out activation, suggesting different mechanisms of ECM affinity regulation. The PI's group has performed genetic screens and proteomic-based experiments to identify intracellular signaling effectors that bind to b8 integrin, but not to other integrin subunits. In this project we will anayze how these effector proteins contribute to avb8 integrin-mediated cell migration using genetically engineered mouse models and primary culture systems. In Aim 1 we will characterize links between avb8 integrin, the cytoplasmic tyrosine phosphatase PTP-PEST, and the Rho GTPase effector protein RhoGDI1. In Aim 2 functional interactions between avb8 integrin and Spinophilin, a cytoskeletal scaffolding protein and regulatory subunit of the serine/threonine protein phosphatase 1 (PP1), will be analyzed. Lastly, integrin-dependent links between Spinophilin/PP1, PTP-PEST and Rho signaling will be explored. In summary, experiments in this project will reveal new and important mechanisms underlying avb8 integrin control of cell adhesion and migration in development and disease.