Mechanisms of Integrin Receptor Transmembrane Signaling

描述（由申请人提供）：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传导的结构基础，以及伴随的细胞内蛋白质之间的信息传递。特别关注细胞粘附受体的整合素家族，这对脊椎动物的功能不可或缺，对血管系统的运作至关重要。整合素由两个非共价相关的亚基组成，称为α和β，具有跨细胞膜双向传递信号的显著能力。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（非活性，内向外和外向内信号）。然而，除了认识到跨膜螺旋的分离伴随着跨膜信号传导之外，关于跨膜螺旋填充、倾斜和膜嵌入的数据，特别是结构数据很少。为了发现细胞骨架蛋白talin与整合素β细胞质尾部结合后的激活信号如何在细胞膜上传递，我们的研究追求以下具体目标：(i)确定每个整合素的单体跨膜螺旋的结构、动力学和膜嵌入？b和？3单元。（ii）异二聚体整合素的结构、相互作用和膜嵌入的阐明？b和？3个跨膜螺旋。（三）评估talin与？3和？ b-?？3跨膜结构、相互作用和膜嵌入。我们正在使用溶液核磁共振波谱来实现这些目标。包含整合素的肽？IIb-?？跨膜尾和胞浆尾重组产生，并在脂质双分子层模型膜中重组。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。血栓的病理表现可导致心脏病发作和中风，为了有效控制和预防血栓，必须了解导致血栓形成的分子事件。因此，我们的研究有助于理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。中风和心脏病是导致死亡的两个主要原因，它们都是由血管系统的病理异常引起的。目前的建议为理解印迹血小板聚集的关键介质提供了结构基础，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.