Regulation of Bone Formation by G-protein Signaling

描述（由申请人提供）：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。骨质疏松症影响着美国超过1000万人。此外，每年因骨折就诊的急诊人数超过300万。由于我们治疗和预防这些疾病的能力仍然非常初级，阐明调节骨形成的机制对于理解骨疾病的病理变化和开发靶向治疗来增加骨形成至关重要。本提案的总体目标是定义在骨生长中新开发的g蛋白信号模型中调节肌肉骨骼组织形成的生物学过程。先前的研究结果表明，仅由合成配体（RASSL）激活的工程受体“Rs1”在成骨细胞中的表达可以显著增加Rs1转基因小鼠的骨量。该提案将在三个特定目标中定义这种表型的基础：1)通过小鼠和体外组织培养模型的结合确定rs1诱导骨形成的细胞机制；2)确定Gs信号对小鼠和胚胎干细胞模型成骨细胞分化的影响；3)利用表达Rs1的成骨细胞的定向表达分析，鉴定由Rs1模拟的内源性gpcr。这些研究的成功完成将确定g蛋白信号通路与其他骨生长机制之间的新相互作用，同时确定天然gpcr可能是促进骨生长的重要临床靶点。此外，该结果将提高我们对成骨细胞、脂肪细胞和骨髓如何在正常骨骼中相互作用的理解。拟议的研究是协调的职业发展计划的一部分，旨在通过研究、课程和辅导，使候选人成为一名杰出的、独立的医生和科学家。候选人将在其导师的指导下获得关于利用基础和转化方法研究发育性疾病的额外培训。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项目所需的技能和经验。

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.