Structure Function Analysis of Integrins alpha1beta1 and alpha2beta2

描述(申请人提供)：整合素是由非共价结合的α和β亚基形成的跨膜受体。β-1亚基与12个α亚基结合，提示α-β-1整合素功能的特异性由α亚基决定。这体现在两个主要的胶原结合受体，整合素α-1-β-1和α-2-β-1，它们不仅对不同的胶原蛋白有不同的亲和力(由它们的胞外结构域决定)，而且以一种严重依赖于它们的跨膜(TM)和细胞质(CT)结构域的方式介导不同的信号。含有整合素的β-1的TM和CT结构域传递信号的分子机制尚不清楚，因为大多数已发表的关于这些结构域的工作是与高度可调节的α-S-β-3整合素一起进行的，并且主要集中在β-3亚单位本身。我们最近发现，整合素α-1和α-2的TM和CT结构域导致了整合素α-1-β-1和α-2-β-1功能的截然不同的特异性。此外，通过整合素α-1和α-2 CT尾部调节特定信号的关键氨基酸已经被确定。因此，本项目的总体目标是确定整合素α-1-β-1和α-2-β-1的TM和CT结构域对其功能特异性的作用机制。特别是，我们将测试这一假设，即整合素α-1-β-1和α-2-β-1的TM或CT结构域中的特定残基对于赋予结构和功能特异性至关重要。为了验证这一假设，我们将：目的1)确定单个完整的α-1、α-2和β-1 TM/CT结构域以及α-1-β-1和α-2-β-1 TM/CT异二聚体的结构。目的2)确定控制细胞功能中整合素α-1-β-1和α-2-β-1的α-1和α-2TM结构域的特异性和功能性的关键氨基酸。目的3)建立TM/CD结构域在整合素α-1-β-1和α-2-β-1功能和特异性中的作用模型。 公共卫生相关性：我们预计这项研究将对整合素α-1-β-1和α-2-β-1的TM和CT结构域发挥作用的结构基础产生新的见解。这一知识是我们理解整合素如何在健康和疾病中从肾小球内的胶原蛋白传递信号的基础。

DESCRIPTION (provided by applicant): Integrins are transmembrane receptors formed by non-covalently bound alpha and beta subunits. The beta-1 subunit binds 12 alpha subunits, suggesting that specificity of function of alpha-beta-1 integrins are determined by the alpha subunits. This is seen in the two major collagen binding receptors, integrins alpha-1-beta-1 and alpha-2-beta-1, which not only have different affinities for various collagens (determined by their extracellular domains), but also mediate different signals in a manner that is critically dependent on their transmembrane (TM) and cytoplasmic (CT) domains. The molecular mechanisms whereby the TM and CT domains of beta-1 containing integrins transduce signals are poorly understood, as most published work on these domains was performed with the highly modulatable alpha-s-beta-3 integrins and focused primarily on the beta-3 subunit itself. We recently showed that integrin alpha-1 and alpha-2 TM and CT domains contribute to the very different specificities of integrin alpha-1-beta-1 and alpha-2-beta-1 function. Moreover, key amino acids that regulate specific signaling by the integrin alpha-1 and alpha-2 CT tails have been identified. Thus, the overall goal of this project is to identify the mechanisms whereby the TM and CT domains of integrins alpha-1-beta-1 and alpha-2-beta-1 contribute to their functional specificity. In particular, we will test the hypothesis that specific residues within the TM or CT domains of integrins alpha-1-beta-1 and alpha-2-beta-1 are critical for conferring structural and functional specificity. To test this hypothesis we will: Aim 1) Determine the structures of the individual integral alpha-1, alpha-2, and beta-1 TM/CT domains and of the alpha-1-beta-1 and alpha-2-beta-1 TM/CT heterodimers. Aim 2) Determine the critical amino acids that govern the specificity and functionality of the alpha-1 and alpha-2 TM domains of integrins alpha-1-beta-1 and alpha-2-beta-1 in cell function. Aim 3) Develop models for the roles of the TM/CD domains in integrin alpha-1-beta-1 and alpha-2-beta-1 function and specificity. PUBLIC HEALTH RELEVANCE: We anticipate that this study will generate novel insights into the structural basis whereby the TM and CT domains of integrins alpha-1-beta-1 and alpha-2-beta-1 function. This knowledge is fundamental to our understanding of how integrins transduce signals from collagens within the glomerulus in both health and disease.