PTH/PTHRP RECEPTORS IN THE BIOLOGY OF ENDOCHONDRAL BONE

对于正常的骨骼， 发展和维护其完整性。该提案的重点是 软骨内骨形成和甲状旁腺激素（PTH），PTH- PTHrP和PTH/PTHrP受体在复合物中起作用 PTH/PTHrP系统与骨骼生长的相互关系 因子及其受体，以及几种胶原蛋白和非胶原蛋白， 骨生物学中不可或缺的胶原蛋白。 PTHrP是 对于正常的骨骼成熟至关重要，正如惊人的 PTHrP基因被大部分删除的小鼠的异常， 同源重组（PTHrP-less）。 最近， PTH和PTHrP都已经从几个物种中克隆出来;它们具有 结合循环激素的独特性质， 钙稳态，以及一种推测的旁分泌/自分泌肽， 对骨骼生物学的重要性。 这些受体也激活 多种效应分子，包括腺苷酸环化酶和 脂酶C已许多生长因素也被证明会影响 对骨骼发育和体内平衡至关重要;其中，目前 有证据表明胰岛素样生长因子（IGF）的成员， 转化生长因子β（TGF β）和骨形态发生 骨形成蛋白（BMPs）调节PTH/PTHrP或受PTH/PTHrP调节 系统 我们计划使用各种方法来了解 PTH和PTHrP调节骨骼基因表达的机制 并定义这些生长因子的影响 对PTHrP和PTH/PRHrP受体mRNA和蛋白表达有影响。 这些 将通过形态学标准和 分子生物学方法在几个系统中。 目标I详细介绍了我们的 初步描述性分析，以表征晚期 正常大鼠、46周龄以下大鼠、 正常和PTHrP-少的胎鼠，以及软骨细胞和 原代培养的成骨细胞。 我们已经开发了一些系统， 我们可以在越来越复杂的情况下分析这些关系， 组织水平--从培养中的原代细胞到器官外植体 和完整的整合在体外和体内研究，我们希望定义 在细胞和器官水平的机制，并与相关的 将这些发现应用于整个动物。 目的二主要分析了 PTH（1-84）和PTHrP（1-141）对生长基因表达的影响 因子、几种胶原蛋白和非胶原蛋白。 目标三 检查相互关系;也就是说，这些影响 生长因子对PTHrP和PTH/PTHrP受体mRNA表达的影响， 蛋白 反过来，对骨骼动态平衡的更好理解， 有助于骨生物学，并导致更合理的治疗 治疗骨质疏松症等疾病

Precise orchestration of myriad of event is necessary for normal skeletal development and maintenance of its integrity. This proposal focuses on endochondral bone formation and the roles parathyroid hormone (PTH), PTH- related peptide (PTHrP) and PTH/PTHrP receptors play in the complex interrelationships between the PTH/PTHrP system and skeletal growth factors and their receptors, and the several collagens and non- collagenous proteins that are integral to bone biology. PTHrP is essential for normal skeletal maturation, as evidenced by striking abnormalities in mice whose PTHrP gene have been largely deleted by homologous recombination (PTHrP-less). Recently, receptors that bind both PTH and PTHrP have been cloned from several species; they have the unique property of binding both a circulating hormone important to calcium homeostasis, and a presumed paracrine/autocrine peptide with obvious importance to bone biology. These receptors also activate multiple effector molecules, including adenylate cyclase and phospholipase C. Numerous growth factors have also been shown to impact critically on skeletal development and homeostasis; among these, current evidence suggests that members of the insulin-like growth factors (IGFs), transforming growth factor beta (TGFbeta), and bone morphogenetic proteins (BMPs) either regulate, or are regulated by the PTH/PTHrP system. We plan to use a variety of approaches to understand the mechanism by which PTH and PTHrP modulate skeletal expression of genes for these growth factors, and to define influences these growth factors have on PTHrP and PTH/PRHrP receptor mRNA and protein expression. These interrelationships will be explored by both morphological criteria and molecular biological approaches in several systems. Aim I details our initial descriptive analyses to characterize gene expression in late fetal skeletal development in normal rats, rats up to 46 weeks of age, both normal and PTHrP-less fetal mice, and in chondrocytic and osteoblastic cells in primary culture. We have developed systems which we can perturb to analyze these relationships at increasingly complex levels of organization--from primary cells in culture, to organ explants and intact integrating in vitro and in vivo studies, we expect to define mechanisms at the cellular and organ level and relate the relevance of these findings to the whole animal. Aim II mainly analyzes the effects of PTH (1-84) and PTHrP (1-141) on expression of genes for growth factors, several collagens and non-collagenous proteins. Aim III examines the reciprocal relationship; that is, the influences of these growth factors on expression of PTHrP and PTH/PTHrP receptor mRNA and protein. Greater understanding of skeletal homeostasis will, in turn, contribute to bone biology in general and lead to more rational therapy for diseases like osteoporosis.