SIGNALING PROPERTIES OF THE PTH/PTHRP RECEPTOR

PTH 1 R刺激至少两种效应物，腺苷酸环化酶（AC）和 磷脂酶C，通过激活Gs和Gq家族的成员。 尽管研究表明第二信使途径 以及PTH和PTHrP在肾脏和骨骼中的特定作用， 数据仍然不确定。 该提案的主要目标是 定义PTH和PTHrP的哪些动作是AC独立的。 我们将 比较由PTH刺激两种AC- 有缺陷的受体突变体，与PTH 1 R在体内和体内的突变体相比， 小鼠 目的I和II询问PTH是否刺激AC非依赖性通路 分别影响成骨细胞生物学和破骨细胞生成。 这些研究将利用新的，克隆的，有条件的- 转化的成骨细胞和骨髓基质细胞系， PTH 1 R基因缺失。 通过稳定转染，PTH 1 R或 AC缺陷突变体将在这些细胞中表达。 相互作用 基因改变的基质细胞和破骨细胞祖细胞之间 将首先确定破骨细胞祖细胞是否表达PTH 1 R， 然后检查PTH是否通过刺激破骨细胞生成来影响破骨细胞生成， AC独立途径。 目标三和四是对目标一和二的补充， 体内，通过评估小鼠的表型，其中两个PTH 1 R基因都具有 被AC缺陷突变体取代我们将研究PTH或 PTHrP通过AC非依赖性途径影响肾脏或 骨功能，特别侧重于建立特定效应器 通路与PTH对骨骼的合成代谢作用有关。 我们也将 检验PTHrP阻断软骨细胞增殖的假设 生长板软骨刺激AC独立机制。 这些体外/体内分析的结果将阐明 对PTH的反应与AC无关。 它们还可以让我们深入了解 优化PTH增加骨量能力的治疗措施， 并进一步加深了我们对影响生长的疾病的理解， 孩子

The PTH1R stimulates at least two effectors, adenylyl cyclase (AC) and phospholipase C, by activating Gs and members of the Gq family. Although studies have suggested links between second messenger pathways and specific actions of PTH and PTHrP in the kidney and in the skeleton, the data remain inconclusive. The major goal of this proposal is to define which actions of PTH and PTHrP are AC-independent. We will compare the biological responses elicited by PTH stimulation of two AC- defective receptor mutants, with those of the PTH1R both in vivo and in mice. Aims I and II ask whether PTH stimulates AC-independent pathways that affect osteoblast biology and osteoclastogenesis, respectively. These studies will take advantage of novel, clonal, conditionally- transformed osteoblastic and marrow stromal cell lines that have both copies of the PTH1R gene deleted. By stable transfection, the PTH1R or the AC-defective mutants will be expressed in these cells. Interactions between genetically-altered stromal cells and osteoclast progenitors will first determine whether osteoclast progenitors express the PTH1R, and then examine whether PTH affects osteoclastogenesis by stimulating AC-independent pathways. Aims III and IV complement Aims I and II in vivo, by assessing the phenotype of mice in whom both PTH1R genes has been replaced by the AC-defective mutant. We will study whether PTH or PTHrP, through AC-independent pathways, affects parameters of renal or bone function, with a special focus on establishing if specific effector pathways are linked to PTH's anabolic actions on bone. We also will test the hypothesis that PTHrP acts to block chondrocyte proliferation of growth-plate cartilage by stimulating AC-independent mechanisms. Results from these in vitro/in vivo analyses will clarify which responses to PTH are AC-independent. They also may give insight into therapeutic measures to optimize PTH's capacity to increase bone mass, and further our understanding of diseases that impair growth in children.