FGF3 RECEPTOR/BMP4: PATHWAYS REGULATING SKELETAL GROWTH

FGF3 受体/BMP4：调节骨骼生长的途径

• 批准号: 6512223
• 负责人: MICHAEL C. NASKI
• 金额: $ 23.77万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-07-15 至 2004-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6512223
• 关键词: biological signal transduction; bone development; bone morphogenetic proteins; cartilage development; cell differentiation; cell growth regulation; cell proliferation; cell senescence; chondrocytes; fibroblast growth factor; gene expression; genetically modified animals; growth factor receptors; growth inhibitors; immunoprecipitation; laboratory mouse; mitogen activated protein kinase; phospholipase C; polymerase chain reaction; protein structure function; western blottings

Fibroblast growth factor receptor 3 (FGFR3) is a chief regulator of endochondral bone growth, as evidenced by the discovery that the most common genetic cause of dwarfism, achondroplasia, results from mutations in FGFR3. This implies that pathways downstream of FGFR3 are central to the control of skeletal growth. Our goals are to understand the signaling pathways used by FGFR3 to control cell proliferation and differentiation during skeletal growth and development. Understanding these pathways will lead to novel interventions for the control of skeletal growth and suggest approaches for promoting cartilage repair and regeneration. We hypothesize that FGFR3 inhibits cell proliferation by accelerating pathways of cell senescence and inhibits cell differentiation by repressing BMP4 expression. These hypotheses are a direct consequence of our preliminary data showing that FGFR3 reduces the number of chondrocytes in S-phase and slows the rate of chondrocyte and osteoprogenitor cell differentiation. Intriguingly, FGFR3 represses the expression of bone morphogenetic protein 4 (BMP4) both in chondrocytes and perichondrial osteoprogenitor cells, suggesting that FGFR3 may synchronize bone growth in the perichondrium with the growth of the epiphyseal growth plate by modulating BMP4 expression. Despite this knowledge, much remains to be learned about how FGFR3 inhibits skeletal growth. Specifically, what are the pathways used by FGFR3 to inhibit cell proliferation and what are the mediators downstream of FGFR3 that inhibit perichondrial and chondrocyte differentiation? Without understanding these fundamental questions there is little hope of designing interventional treatments for dwarfing conditions such as achondroplasia. We will address these questions and test our hypotheses by pursuing the following specific aims: 1) Investigate how FGFR3 inhibits chondrocyte proliferation by testing the hypothesis that FGFR3 accelerates cell cycle senescence; 2a) Determine how BMP4 acts as a mediator of FGFR3 signaling by targeting the expression of BMP4 to cartilage of transgenic mice and 2b) Using a cre-lox system to express BMP4 in transgenic mice, investigate the separate and combined roles of BMP4 in cartilage and the perichondrium. These studies will utilize unique reagents, including FGFR3 transgenic mice, created during our preliminary studies. Using these reagents we can directly test what effects of FGFR3 are consequences of altered BMP4 expression. These studies will fundamentally advance our understanding of the communication of the growth plate and the perichondrium and unravel novel growth regulatory pathways of FGFR3 and BMP4. We anticipate these studies will suggest new ways to control skeletal growth and to promote cartilage repair and regeneration.

成纤维细胞生长因子受体 3 (FGFR3) 是软骨内骨生长的主要调节因子，侏儒症最常见的遗传原因软骨发育不全是由 FGFR3 突变引起的这一发现就证明了这一点。 这意味着 FGFR3 下游通路对于骨骼生长的控制至关重要。 我们的目标是了解 FGFR3 在骨骼生长和发育过程中控制细胞增殖和分化的信号通路。 了解这些途径将导致控制骨骼生长的新干预措施，并提出促进软骨修复和再生的方法。 我们假设 FGFR3 通过加速细胞衰老途径来抑制细胞增殖，并通过抑制 BMP4 表达来抑制细胞分化。这些假设是我们初步数据的直接结果，表明 FGFR3 减少了 S 期软骨细胞的数量，并减慢了软骨细胞和骨祖细胞的分化速度。 有趣的是，FGFR3 抑制软骨细胞和软骨膜骨祖细胞中骨形态发生蛋白 4 (BMP4) 的表达，表明 FGFR3 可能通过调节 BMP4 表达使软骨膜中的骨生长与骨骺生长板的生长同步。尽管有了这些知识，但关于 FGFR3 如何抑制骨骼生长，仍有很多知识有待了解。 具体来说，FGFR3 通过哪些途径抑制细胞增殖，以及 FGFR3 下游抑制软骨膜和软骨细胞分化的介质是什么？ 如果不了解这些基本问题，设计针对软骨发育不全等侏儒症的介入治疗方法就几乎没有希望。 我们将通过追求以下具体目标来解决这些问题并检验我们的假设：1）通过检验 FGFR3 加速细胞周期衰老的假设来研究 FGFR3 如何抑制软骨细胞增殖； 2a) 通过将 BMP4 的表达靶向转基因小鼠的软骨来确定 BMP4 如何作为 FGFR3 信号传导的介质，2b) 使用 cre-lox 系统在转基因小鼠中表达 BMP4，研究 BMP4 在软骨和软骨膜中的单独和组合作用。这些研究将利用我们在初步研究期间创建的独特试剂，包括 FGFR3 转基因小鼠。 使用这些试剂，我们可以直接测试 FGFR3 的影响是 BMP4 表达改变的结果。 这些研究将从根本上增进我们对生长板和软骨膜通讯的理解，并揭示 FGFR3 和 BMP4 的新生长调节途径。 我们预计这些研究将提出控制骨骼生长和促进软骨修复和再生的新方法。