FGF3 RECEPTOR/BMP4: PATHWAYS REGULATING SKELETAL GROWTH

FGF3 受体/BMP4：调节骨骼生长的途径

• 批准号: 6375337
• 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/6375337
• 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）是内向骨骨生长的主要调节剂，这一发现证明了矮人的最常见遗传原因，阿诺氏症，是FGFR3突变引起的。 这意味着FGFR3下游的途径是控制骨骼生长的核心。 我们的目标是了解FGFR3用于控制骨骼生长和发育过程中细胞增殖和分化的信号传导途径。 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通过加速细胞衰老的途径来抑制细胞增殖，并通过抑制BMP4表达来抑制细胞分化。这些假设是我们的初步数据的直接结果，该数据表明FGFR3减少了S期中软骨细胞的数量，并减少了软骨细胞和骨质基细胞分化的速率。 引人入胜的是，FGFR3抑制软骨细胞和per骨骨骨基因生激素细胞中骨形态发生蛋白4（BMP4）的表达，这表明FGFR3可以通过调制BMP4的表达来使perichondrium的骨骼生长同步，并同步。尽管有这些知识，但有关FGFR3如何抑制骨骼生长的知识仍然有很多待了解。 具体而言，FGFR3用来抑制细胞增殖的途径是什么？FGFR3下游的介体是什么抑制了围骨和软骨细胞分化的？ 在不理解这些基本问题的情况下，为矮人疾病（如刺激性疾病）设计介入的治疗几乎没有希望。 我们将通过追求以下特定目的来解决这些问题并检验我们的假设：1）研究FGFR3如何通过测试FGFR3加速细胞周期衰老的假设来抑制软骨细胞增殖； 2A）通过将BMP4的表达靶向转基因小鼠的软骨和2B），确定BMP4如何用作FGFR3信号传导的介体，并使用CRE-LOX系统在转基因小鼠中表达BMP4，研究BMP4在软骨中和Perichondrium中的单独和组合作用。这些研究将利用在我们的初步研究中创建的独特试剂，包括FGFR3转基因小鼠。 使用这些试剂，我们可以直接测试FGFR3的哪些影响是BMP4表达改变的后果。 这些研究从根本上可以提高我们对FGFR3和BMP4的生长板以及新颖的生长调节途径的了解。 我们预计这些研究将提出控制骨骼生长并促进软骨修复和再生的新方法。