Mechanisms of Integrin Receptor Transmembrane Signaling

描述(申请人提供)：我们的长期研究兴趣在于努力了解细胞表面受体跨膜信号的结构基础，以及细胞内蛋白质之间的伴随信息传递。特别关注的是细胞黏附受体的整合素家族，它对脊椎动物的功能是不可或缺的，对血管系统的运行也是至关重要的。整合素由两个非共价结合的亚基组成，称为α和β，具有在细胞膜上双向传递信号的非凡能力。要做到这一点，它们的两个亚基的单个跨膜螺旋必须编码至少三种功能状态(不活跃、由内向外和由外向内信号)。然而，除了认识到跨膜螺旋的分离伴随着跨膜信号转导，几乎没有关于跨膜螺旋堆积、倾斜和膜包埋的数据，特别是结构数据。为了弄清细胞骨架蛋白talin与整合素β胞浆尾巴结合后激活信号是如何通过细胞膜传递的，我们的研究追求了以下具体目标：(I)确定每个整合素IIB和β3亚基单体跨膜螺旋的结构、动力学和膜嵌入。(Ii)阐明异二聚体整合素？IIB和？3跨膜螺旋的结构、相互作用和膜包埋。(3)评估Talin与？3和？IIB-？3跨膜结构、相互作用和膜包埋的后果。我们正在使用溶液核磁共振波谱来实现这些目标。包含整合素IIB-3跨膜和胞浆尾巴的多肽被重组产生，并在脂质双层模型膜中重组。整合素？IIB-？3介导血小板聚集，因此是血栓形成的关键调节因子。为了有效地控制和预防血栓，血栓的病理表现会导致心脏病发作和中风，必须了解导致它们形成的分子事件。因此，我们的研究有助于了解血管系统中分子和细胞的相互作用，并将有助于开发治疗血管疾病的药物和疗法。公共卫生相关性中风和心脏病发作是导致死亡的两个主要原因，它们是由血管系统的病理异常引起的。目前的建议为了解印迹血小板聚集的关键介体提供了结构基础，并将有助于通过药物控制这一过程。

DESCRIPTION (provided by applicant): Our long-term research interest lies in striving to understand the structural basis of cell surface receptor transmembrane signaling and the concomitant relay of information to and from intracellular proteins. Particular focus is placed on the integrin family of cell-adhesion receptors, which is indispensable for the functioning of vertebrates and is of central importance to the operation of the vascular system. Integrins consist of two non-covalently associated subunits, termed alpha and beta, and possess the remarkable ability to transmit signals bidirectionally across the cell membrane. To do so, the single transmembrane helices of their two subunits must encode at least three functional states (inactive, inside-out and outside-in signaling). However, aside from recognizing that a separation of the transmembrane helices accompanies transmembrane signaling, little data, in particular structural data, is available about transmembrane helix packing, tilt and membrane embedding. In an effort to discover how an activating signal, following the binding of the cytoskeletal protein talin to the integrin beta cytosolic tail, is transmitted across the cell membrane, our research pursues the following specific aims: (i) Determination of the structure, dynamics and membrane embedding of the monomeric transmembrane helix of each integrin ?IIb and ?3 subunit. (ii) Elucidation of the structure, interaction and membrane embedding of the heterodimeric integrin ?IIb and ?3 transmembrane helices. (iii) Evaluation of the consequences of talin binding to the ?3 and ?IIb-??3 transmembrane structure, interaction and membrane embedding. We are using solution NMR spectroscopy to accomplish these goals. Peptides encompassing the integrin ?IIb-??3 transmembrane and cytosolic tails are produced recombinantly and they are reconstituted in lipid bilayer model membranes. Integrin ?IIb-??3 mediates blood platelet aggregation and, as such, is a key regulator of thrombosis. To effectively control and, if applicable, prevent thrombi, whose pathological appearances lead to heart attack and stroke, the molecular events leading to their formation must be understood. Thus, our research contributes to the understanding of the interactions of molecules and cells within the vascular system, and will aid in the development of drugs and therapies to treat vascular diseases. PUBLIC HEALTH RELEVANCE Stroke and heart attack, two of the major causes of death, arise from pathological aberrations of the vascular system. The current proposal provides the structural basis for understanding a key mediator of blot platelet aggregation and will aid in providing control of this process by drugs.