Structural and functional analyses of rat receptor activator of NF-kb ligand

大鼠RANKL （Xu and Zheng, Rat RANKL, australian provisional Patent PQ3147）具有多种生物活性，包括破骨细胞分化和极化、树突状细胞功能等。RANKL的过量产生或活性增加可导致过度的破骨细胞形成、激活和骨吸收。这一过程导致了许多常见的骨溶解性疾病，如骨质疏松症、佩吉特病、骨转移性疾病、关节炎、无菌性骨松动和骨折不愈合。本文就RANKL分子结构在其生物学功能中的作用这一重要而基本的问题进行了探讨。我们已经确定，tnf样核心结构域是功能性结构域，对破骨细胞发生、破骨细胞极化和防止fas触发的细胞凋亡很重要。本研究将利用位点定向诱变和蛋白截断分析进一步表征RANKL的tnf样核心结构域的突变形式，并评估它们各自与OPG和RANK的结合活性，以及它们在体外和体内的生物活性。这将有助于我们更好地理解RANKL的结构-功能关系。理想情况下，我们希望开发一种相关药物来抑制骨质疏松症等骨科相关疾病的骨溶解。这种优化的分子可以成为一种有效的治疗药物，选择性地抑制破骨细胞的形成和骨吸收。

Rat RANKL (Xu and Zheng, rat RANKL, AustraliaProvisional Patent PQ3147) has a variety of biological activities including osteoclast differentiation and polarization, and dendritic cell function. Overproduction or increased activity of RANKL can result in excessive osteoclast formation, activation, and bone resorption. This process contributes to many common bone lytic disorders such as osteoporosis, Paget's disease, bone metastatic diseases, arthritis, aseptic bone loosening and non-union of fractures. This proposal addresses the important and fundamental issue of RANKL regarding the role of molecular structure on its biological function. We have established that the TNF-like core domain is the functional domain, important for osteoclastogenesis, osteoclast polarisation and protecting against Fas-triggered apoptosis. This proposal will further characterise the mutant forms of the TNF-like core domain of RANKL using site directed mutagenesis and protein truncation analysis, and assess their respective binding activities to OPG and RANK, and their biological activities both in vitro and in vivo. It will lead us into better understanding of the structure-function relationship of RANKL. Ideally, we would like to develop a relative agent for the suppression of osteolysis in orthopaedic related diseases including osteoporosis. Such an optimized molecule could become a potent therapeutic agent that selectively inhibits osteoclast formation and bone resorption.