PTH/PTHRP RECEPTORS IN THE BIOLOGY OF ENDOCHONDRAL BONE

对于正常的骨骼来说，对无数事件的精确编排是必要的 发展和维护其完整性。这项提案的重点是 甲状旁腺激素在软骨内成骨中的作用 相关肽(PTHrP)和PTH/PTHrP受体在复合体中发挥作用 甲状旁腺素/甲状旁腺素rP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 胶原蛋白是骨生物学所必需的。PTHrP是 对于正常的骨骼成熟是必不可少的，这一点从以下几个方面得到了证明 PTHrP基因大部分缺失的小鼠的异常 同源重组(PTHrP-less)。最近，结合的受体 PTH和PTHrP都是从几个物种中克隆出来的；它们具有 结合两种循环荷尔蒙的独特性质对 钙稳态，以及推测的旁分泌/自分泌多肽 对骨骼生物学的重要性显而易见。这些受体也会激活 多个效应分子，包括腺苷环化酶和 磷脂酶C。许多生长因子也被证明对 关于骨骼发育和动态平衡的批判性研究；其中， 有证据表明，胰岛素样生长因子(IGF)成员， 转化生长因子β与骨形态发生 蛋白质(BMP)调节甲状旁腺素/甲状旁腺素rP或受其调节 系统。我们计划使用多种方法来了解 PTH和PTHrP调控基因骨架表达的机制 对于这些增长因素，并定义这些增长因素的影响 对PTHrP和PTH/PRHrP受体的mRNA和蛋白表达有影响。这些 相互关系将通过形态标准和 几个系统中的分子生物学方法。Aim I详细介绍了我们的 对晚期基因表达特征的初步描述性分析 正常大鼠胎儿骨骼发育，46周龄以下大鼠， 正常和PTHrP缺乏的胎鼠，以及软骨细胞和 原代培养的成骨细胞。我们已经开发了这样的系统 我们可以在日益复杂的情况下不安地分析这些关系 组织水平--从培养中的原代细胞到器官外植体 并完整地整合了体外和体内研究，我们预计将确定 在细胞和器官水平上的机制，并与 将这些发现推广到整个动物身上。AIM II主要分析了这些影响 PTH(1-84)和PTHrP(1-141)对生长相关基因表达的影响 因子、几种胶原蛋白和非胶原蛋白。AIM III 检查互惠关系；也就是， 生长因子对甲状旁腺激素受体及甲状旁腺素/甲状旁腺素受体基因表达的影响 蛋白。反过来，对骨骼动态平衡的更多了解将 总体上对骨生物学做出贡献，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.