Mechanisms and function of the microtubule podosome connection in osteoclasts

描述（由申请方提供）：骨吸收增加是多种骨病的原因，无论是全身性（例如骨质疏松症、佩吉特病、甲状旁腺功能亢进）还是局部性（类风湿性关节炎、牙周病、多发性骨髓瘤、肿瘤骨质溶解等）。尽管存在几种抗吸收药物，但不良反应的证据正在出现。因此，更好地了解破骨细胞（OC）和骨吸收的生物学仍然具有极其重要的临床意义。我们的实验室已经投入了大量的资金在OC生物学和骨吸收的详细分子理解。这项工作的最显著的特点之一，由许多其他实验室的支持，是证明的OC附着到骨的至关重要的，介导的一个专门的粘附结构，肌动蛋白的podosome，这在OC是专门组织在一个外围带（肌动蛋白环），并最终在密封区时，OC是在骨和积极再吸收。足状体带的形成是OC特有的特征。一个重要的突破是证明了微管（MT）在将podosome组织成肌动蛋白环和密封区中以及因此在骨吸收中所起的关键作用（Destaing等，2004; Gil-Henn等，2007; Purev等人，2009年）的报告。本申请的主要目的是进一步阐明MT连接至并调节足体的分子机制，特别是从簇到外周带的过渡以及骨吸收。我们的初步数据显示，MTs，+提示蛋白EB 1，corneumn和podosomes之间的功能相互作用，所需的podosome带的形成。我们的建议集中在分子调控的+端的MT和他们的相互作用与肌动蛋白和肌动蛋白调节蛋白的podosomes在OC。这将有助于理解调节周边带中的podosomes及其组织的定位和周转的机制，这是建立密封区的OC特异性和必要步骤，其本身是骨吸收所需的。我们建议：1-确定的作用+TIPs蛋白EB 1在连接MT的肌动蛋白动力学在podosomes。2-确定coronin（及其同源物HS 1）的作用及其与EB 1在线粒体和肌动蛋白动力学之间的联系中的相互作用。3-分析Src和HDAC 6的作用，即酪氨酸磷酸化和乙酰化，在线粒体和肌动蛋白动力学之间的联系。这些研究可能开辟新的治疗途径来调节骨吸收，考虑到podosomes和invadopodia之间的相似性，对骨质疏松症，溶骨性疾病和癌症的治疗具有潜在的影响。 公共卫生相关性：骨吸收增加是多种骨疾病的原因，无论是全身性的（例如骨质疏松症、佩吉特病、甲状旁腺功能亢进）还是局部的（类风湿性关节炎、牙周病、多发性骨髓瘤、原发性或转移性肿瘤骨质溶解等）。本申请的主要目的是进一步阐明 破骨细胞附着和吸收骨的分子机制，以更好地了解破骨细胞和骨吸收的生物学，从而设计新的和更安全的药物。

DESCRIPTION (provided by applicant): Increased osteoclastic resorption is responsible for multiple bone diseases, whether systemic (osteoporosis, Paget's disease, hyper-parathyroidism for instance) or local (rheumatoid arthritis, periodontal disease, multiple myeloma, tumor osteolysis etc.). Despite the existence of several anti- resorptive drugs, evidence of unwanted effects is emerging. It therefore remains of the utmost clinical importance to better understand the biology of the osteoclast (OC) and of bone resorption. Our laboratory has been heavily invested in the detailed molecular understanding of OC biology and bone resorption. One of the most salient features of this work, supported by many other laboratories, is the demonstration of the critical importance of the attachment of the OC to bone, mediated by a specialized adhesion structure, the actin-containing podosome, which in OCs is specifically organized in a peripheral belt (the actin ring) and ultimately in a sealing zone when OCs are on bone and actively resorbing. The formation of a podosome belt is an OC-specific feature. An important breakthrough has been the demonstration of the critical role played by microtubules (MTs) in the organization of podosomes into an actin ring and a sealing zone and consequently in bone resorption (Destaing et al. 2004; Gil-Henn et al., 2007; Purev et al., 2009). The primary goal of this application is to further elucidate the molecular mechanisms by which MTs are connected to and regulate the podosomes, and in particular the transition from clusters to a peripheral belt, and bone resorption. Our preliminary data revealed a functional interaction between MTs, the +Tip protein EB1, cortactin and podosomes, required for the formation of podosome belts. Our proposal focuses on the molecular regulation of the + ends of MTs and of their interaction with actin and actin-regulating proteins in podosomes in OCs. This will help understand the mechanisms that regulate the localization and turnover of podosomes and their organization in a peripheral belt, an OC-specific and necessary step in the establishment of the sealing zone, itself required for bone resorption. We propose to: 1- Determine the role of the +TIPs protein EB1 in linking MTs to actin dynamics in podosomes. 2- Determine the role of cortactin (and its close homolog HS1) and its interaction with EB1 in the link between MTs and actin dynamics in podosomes. 3- Analyze the role of Src and HDAC6, i.e. Tyrosine phosphorylation and acetylation, in the link between MTs and actin dynamics in podosomes. The studies may open new therapeutic avenues to regulate bone resorption, with potential impact on the treatment of osteoporosis, osteolytic diseases and also cancer, given the similarities between podosomes and invadopodia. PUBLIC HEALTH RELEVANCE: Increased osteoclastic resorption is responsible for multiple bone diseases, whether systemic (osteoporosis, Paget's disease, hyper-parathyroidism for instance) or local (rheumatoid arthritis, periodontal disease, multiple myeloma, primary or metastatic tumor osteolysis etc.). The primary goal of this application is to further elucidate the molecular mechanisms by which osteoclast attach to and resorb bone to better understand the biology of the osteoclast and of bone resorption to design new and safer drugs.