Mechanisms of RANKL Mediated Osteoclast Activation

RANKL 介导的破骨细胞激活机制

基本信息

批准号：
8277094
负责人：
Steven L Teitelbaum
金额：
$ 51.3万
依托单位：
WASHINGTON UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1983
资助国家：
美国
起止时间：
1983-09-01 至 2014-05-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Inflammatory osteolysis, as occurs in rheumatoid arthritis and orthopedic implant loosening, reflects accelerated osteoclast (OC) recruitment and activation. Hence, discovering the means by which local inflammation recruits and activates OCs is central to preventing this crippling complication. Our overriding goal has been to detail the mechanisms by which cytokines, such as TNF, RANKL and M-CSF mediate bone loss. We have achieved the aims of our previous application by characterizing the contributions of various TNF target cells to the osteoclastogenic process and detailing many of the intracellular events by which TNF promotes osteoclastogenesis. In the present proposal we turn to the cytokine essential for all pathological bone resorption, namely RANKL, whose crystal structure, in complex with its receptor, RANK, we resolved in the current funding period. While RANKL is essential for OC differentiation, it also enhances the bone resorptive activity of the mature OC, a process we find depends upon the cytokine's regulation of the cytoskeletal adaptor protein, paxillin and the small GTPase, Rac. Furthermore, our resolution of the RANKL/RANK crystal structure and that of RANKL with the cysteine-rich domains of OPG, the decoy receptor, positions us to develop structure-based RANKL antagonists to arrest RANK signaling in the OC. Given that inhibition of the RANK signaling pathway has proven therapeutic benefit, these novel RANKL inhibitors may impact the treatment of pathological osteolysis. Thus, we hypothesize that: 1) RANKL activation of the OC is mediated via paxillin 2) RANKL activation of the OC is mediated via Rac and 3) Structure-based RANKL antagonists will arrest OC development and function. Our Specific Aims are therefore to 1) Determine the mechanisms by which paxillin mediates RANKL activation of the OC 2) Determine the mechanisms by which RANKL activates Rac in the OC and 3) Engineer variants of RANKL and OPG that disrupt RANK signaling in the OC. PUBLIC HEALTH RELEVANCE. Osteoclasts are the cells which destroy bone, and thus, their increased activity is responsible for most forms of pathological bone loss such as osteoporosis or that attending rheumatoid arthritis. The key molecule which activates ostoclasts is known as RANK ligand (RANKL). The purpose of this proposal is to gain insight into the mechanism by which RANKL activates osteoclasts and to design candidate drugs which will inhibit this event and consequently, prevent pathological bone loss.

描述（由申请人提供）：炎症性骨溶解，如类风湿关节炎和骨科植入物松动，反映了加速的破骨细胞（OC）募集和激活。因此，发现局部炎症募集和激活OCS的手段对于防止这种残酷的并发症至关重要。我们的压倒性目标是详细说明细胞因子（例如TNF，RANKL和M-CSF）介导骨质流失的机制。我们已经通过表征各种TNF靶细胞对破骨碎片生成过程的贡献，并详细介绍了TNF促进破骨细胞发生的许多细胞内事件，从而实现了先前应用的目的。在目前的建议中，我们转向所有病理骨吸收必不可少的细胞因子，即RankL，其晶体结构与其受体的复杂级别，我们在当前的融资期内解决了。尽管RANKL对于OC分化至关重要，但它还增强了成熟OC的骨吸收活性，我们发现的过程取决于细胞因子对细胞骨架衔接蛋白Paxillin和小GTPase的调节。此外，我们对RANK/Rank Crystal结构的分辨率以及RankL与诱饵受体的富含半胱氨酸的域的分辨率，使我们定位基于结构的RANKL拮抗剂，以在OC中阻止秩信号。鉴于对等级信号传导途径的抑制已被证明是治疗益处，因此这些新型的RANKL抑制剂可能会影响病理骨溶解的治疗。因此，我们假设：1）OC的RANKL激活是通过Paxillin 2）通过RAC介导的OC的RANKL激活，而3）基于结构的RANKL拮抗剂将阻止OC的开发和功能。因此，我们的具体目的是1）确定帕克西林介导OC的RANKL激活的机制2）确定RANKL在OC中激活RAC的机制和3）RANKL和OPG的工程师变体，从而破坏OC中的等级信号。公共卫生相关性。破骨细胞是破坏骨骼的细胞，因此，它们的活动增加是导致大多数形式的病理骨质流失，例如骨质疏松症或参加类风湿关节炎。激活Ostoclasts的关键分子称为秩配体（RANKL）。该提案的目的是深入了解Rankl激活破骨细胞并设计候选药物的机制，从而抑制此事件，从而防止病理骨质流失。