Regulation of Bone Formation by G-protein Signaling

描述(申请人提供)：影响骨骼和关节的肌肉骨骼疾病是一个日益严重的健康问题。美国有1000多万人患有骨质疏松症。此外，每年有300多万人次因骨折而前往急诊科就诊。由于我们治疗和预防这些疾病的能力仍然非常初级，阐明骨形成的调节机制对于了解骨疾病的病理变化和开发靶向治疗以促进骨形成至关重要。这项建议的总体目标是在一种新开发的G蛋白信号在骨生长中的模型中定义调节肌肉骨骼组织形成的生物过程。先前的结果表明，在成骨细胞中表达仅由合成配体(RASSL)激活的工程化受体“Rs1”，可以显著增加Rs1转基因小鼠的骨量。这项建议将从三个具体目标确定这种表型的基础：1)结合小鼠和体外组织培养模型确定Rs1诱导成骨的细胞机制；2)确定Gs信号如何影响小鼠和胚胎干细胞模型中的成骨细胞分化；以及3)通过对表达Rs1的成骨细胞进行定向表达分析，鉴定Rs1模仿的内源性GPCRs。这些研究的成功完成将确定G蛋白信号通路和其他骨生长机制之间的新的相互作用，同时确定可能是促进骨生长的重要临床靶点的天然GPCR。此外，这些结果将提高我们对成骨细胞、脂肪细胞和骨髓在正常骨骼中如何相互作用的理解。这项拟议的研究是一个协调的职业发展计划的一部分，旨在通过研究、课程作业和教程为候选人准备成为一名杰出的、独立的内科科学家。候选人将在他的导师的指导下接受关于使用基本和翻译方法研究发育疾病的额外培训。最后，指导委员会将确保候选人在职业发展奖结束时获得成功指导独立研究计划所需的技能和经验。

DESCRIPTION (provided by applicant): Musculoskeletal disorders affecting the bones and joints are a growing health problem. Osteoporosis affects over 10 million people in the United States. In addition, bone fractures result in over 3 million emergency department visits a year. Since our ability to treat and prevent these diseases is still very rudimentary, elucidating the mechanisms that regulate bone formation is crucial for understanding the pathologic changes in bone diseases and for developing targeted treatments to increase bone formation. The overall objective of this proposal is to define the biological processes regulating the formation of musculoskeletal tissues in a newly developed model of G-protein signaling in bone growth. Prior results showed that expression in osteoblasts of an engineered receptor activated solely by synthetic ligand (RASSL), "Rs1," could dramatically increases bone mass in Rs1 transgenic mice. This proposal will define the basis of this phenotype in three specific aims: 1) determine the cellular mechanisms of Rs1-induced bone formation with a combination of mouse and in vitro tissue culture models; 2) determine how Gs signals affect osteoblast differentiation in mouse and embryonic stem cell models; and 3) identify endogenous GPCRs mimicked by Rs1 using directed expression analysis of Rs1-expressing osteoblasts. Successful completion of these studies will identify new interactions between G-protein signaling pathways and other mechanisms of bone growth, while identifying native GPCRs that may be important clinical targets for increasing bone growth. In addition, the results will improve our understanding of how osteoblasts, adipocytes, and bone marrow interact in normal bone. The proposed research is part of a coordinated career development plan to prepare the candidate to be an outstanding, independent physician-scientist through research, coursework, and tutorials. The candidate will acquire additional training under his mentors' guidance on the utilization of fundamental and translational methods for studying developmental diseases. Finally, a mentoring committee will ensure that the candidate acquires the skills and experience necessary to successfully direct an independent research program by the conclusion of the Career Development Award.