Understanding the role of phospholipids in integrin signaling

描述（由申请人提供）：整合素是参与细胞粘附和细胞-细胞相互作用调节的异源二聚体细胞表面受体。因此，它们在许多对人类健康具有重要意义的生物过程中发挥着关键作用。我们提出的研究工作的目标是提供第一个定量的了解膜和它的脂质组成的作用的整合素激活和信号传导的机制。我们使用了一种新的方法，通过采用纳米盘，均匀的自组装纳米级盘状双层，以提供膜组成的精确控制。我们耦合这种实验方法与分子动力学模拟采用一种新的膜模拟，允许增强采样在原子分辨率，从而详细描述发生在蛋白质-膜界面的相互作用。通过集中我们的实验和理论推力塔林，一个关键的活化剂的整合素参与由内而外的信号，我们回答的问题，塔林如何从事膜和阴离子磷脂的存在，特别是PIP 2，调节这种重要的相互作用。此外，我们剖析了塔林激活的机制，从其自抑制形式分离与磷脂相互作用的贡献，以及效应器Rap 1，RIAM和PIPK γ。通过这项综合研究计划，我们试图了解这些相互作用的总和如何调节整合素的激活和控制其对配体结合的亲和力。 公共卫生相关性：整合素是一类重要的粘附受体，其参与广泛的生物过程，包括胚胎发育、止血、细胞迁移、伤口愈合和免疫应答，并且其受损的功能与关键的人类疾病如关节炎、心脏病发作、中风和癌症有关。该项目旨在研究膜表面在活性整合素复合物形成中的作用，主要关注衔接蛋白talin。采用一套紧密耦合的理论和实验生物物理技术，我们的目标是提出一个详细的结构视图激活整合素的膜表面。

DESCRIPTION (provided by applicant): Integrins are heterodimeric cell surface receptors involved in the regulation of cellular adhesion and cell-cell interactions. As such they play a critical role in many biological processes of importance to human health. The goal of our proposed research effort is to provide the first quantitative understanding of role of the membrane and its lipid composition on the mechanism of integrin activation and signaling. We use a novel approach by employing Nanodiscs, homogeneous self- assembled nanometer scale discoidal bilayers to provide precise control of the membrane composition. We couple this experimental approach with molecular dynamic simulations employing a novel membrane mimetic that allows enhanced sampling at an atomic resolution, thereby a detailed description of the interactions occurring at the protein-membrane interface. By focusing our experimental and theoretical thrusts on talin, a key activator of integrin involved in inside-out signaling, we answr questions as to how talin engages the membrane and how the presence of anionic phospholipids, in particular PIP2, regulates this important interaction. In addition, we dissect th mechanism of talin activation from its auto-inhibited form separating the contributions from interactions with phospholipids, and that of the effectors Rap1, RIAM, and PIPKgamma. Through this integrated research plan we seek to understand how the sum of these interactions regulates the activation of integrin and control its affinity for ligand binding. PUBLIC HEALTH RELEVANCE: Integrins are an important class of adhesion receptors that are involved in a wide range of biological processes including embryonic development, hemostasis, cell migration, wound healing, and the immune response and their impaired function has been linked to key human diseases such as arthritis, heart attack, stroke, and cancer. This project seeks to investigate the role of the membrane surface in the formation of active integrin complexes with primary focus on the adapter protein talin. Employing a closely coupled set of theoretical and experimental biophysical techniques, the goal is to present a detailed structural view for activation of integrin on a membrane surface.