Mechanisms of AVB3 Integrin Mediated Bone Resorption

描述（由申请人提供）：骨细胞骨吸收需要骨降解细胞和并置基质之间的物理亲密性。在这方面，我们集中在破骨细胞的形成和功能的整合素的作用，并发现整合素avb 3是这个过程的基础。尽管这些研究最终导致了整联蛋白抑制剂的发展，这些抑制剂延缓了实验性和人类绝经后骨质疏松症，但将avb 3作为治疗靶点的优化将取决于描述其在破骨细胞中发挥作用的机制。我们在最初的申请中提出鉴定b3整联蛋白胞质结构域的特定组分，其1）调节骨细胞内信号分子的活化，2）组织破骨细胞细胞骨架，3）调节破骨细胞再吸收骨的能力。使用我们实验室中产生的β 3-/-小鼠，我们实现了这些特定目标中的每一个。在本申请中，我们继续研究α v β 3传递重要的骨细胞内信号的机制。因此，我们提出了一个模型，其中alphavbeta 3的配体占用提示形成的三元信号复合物组成的整合素，c-Src和Syk/Zap 70。该avb 3相关复合物反过来激活Vav 3和Rac，最终导致OC细胞骨架和骨吸收的组织化。与我们最初的应用类似，我们能够实现我们的目标，因为我们手头有基因缺失小鼠来解决每个问题，以及在来自这些小鼠的破骨细胞中表达感兴趣蛋白的能力。因此，我们假设：1）α v β 3和c-Src在破骨细胞中相互作用; 2）c-Src和Syk家族激酶介导α v β 3激活Vav 3; 3）Rac，avb 3的效应子，调节破骨细胞的形成和/或功能。因此，我们的具体目标是确定1）c-Src和alphavbeta 3在破骨细胞中相互作用的机制; 2）Syk/Zap 70和alphavbeta 3在破骨细胞中激活Vav 3; 3）Rac，avb 3的效应物调节破骨细胞形成和/或功能。

DESCRIPTION (provided by applicant): Osteoclastic bone resorption requires physical intimacy between the bone degrading cell and the juxtaposed matrix. In this regard, we have focused on the role of integrins in osteoclast formation and function and find that the integrin avb3 is fundamental to the process. While, these studies have eventuated in the development of integrin inhibitory agents which retard experimental and human post-menopausal osteoporosis, optimizing avb3 as a therapeutic target will depend upon delineating the mechanisms by which it functions in the osteoclast. We proposed in our original application to identify specific components of the b3 integrin cytoplasmic domain which 1) regulate activation of intraosteoclastic signaling molecules 2) organize the osteoclast cytoskeleton and 3) regulate the capacity of osteoclasts to resorb bone. Using beta3-/- mice generated in our laboratory we have achieved each of these Specific Aims. In the current application, we continue to address the mechanisms by which alphavbeta3 transmits important intra-osteoclastic signals. Thus, we propose a model in which ligand occupancy of alphavbeta3 prompts formation of a ternary signaling complex consisting of the integrin, c-Src and Syk/Zap70. This avb3 associated complex, in turn, activates Vav3 and Rac, eventuating in organization of the OC cytoskeleton and bone resorption. Similar to our original application, we are positioned to achieve our goals as we have in hand gene deleted mice to address each issue, as well as the capacity to express proteins of interest in osteoclasts derived from such mice. We, therefore, hypothesize that 1) alphavbeta3 and c-Src interact in osteoclasts; 2) c-Src and Syk family kinases mediate alphavbeta3 activation of Vav3; 3) Rac, an effector of avb3, regulates osteoclast formation and/or function. Thus, our Specific Aims are to determine the mechanisms by which 1) c-Src and alphavbeta3 interact in osteoclasts; 2) Syk/Zap70 and alphavbeta3 activate Vav3 in osteoclasts; and 3) Rac, an effector of avb3 regulates osteoclast formation and/or function.