SIGNALING PROPERTIES OF THE PTH/PTHRP RECEPTOR

PTH1R刺激至少两个效应器，腺苷环化酶(AC)和 磷脂酶C，通过激活Gs和GQ家族成员。 尽管研究表明第二信使通路之间存在联系 以及甲状旁腺素和甲状旁腺素在肾脏和骨骼中的特定作用， 数据仍然没有定论。这项建议的主要目标是 定义PTH和PTHrP的哪些动作是AC独立的。我们会 比较刺激甲状旁腺素引起的两种交感神经节细胞的生物学反应 受体缺陷突变体，体内和体内的PTH1R 老鼠。AIMS I和II问甲状旁腺素是否刺激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同时具有 PTH1R基因拷贝缺失。通过稳定转染，PTH1R或 AC缺陷突变体将在这些细胞中表达。互动 在基因改变的基质细胞和破骨细胞前体细胞之间 将首先确定破骨细胞前体细胞是否表达PTH1R， 然后研究甲状旁腺激素是否通过刺激影响破骨细胞的形成 不依赖AC的通路。目标三和目标四补充目标一和目标二 活体，通过评估PTH1R基因都有表型的小鼠 已经被AC缺陷突变体取代了。我们将研究PTH或 甲状旁腺激素受体通过AC非依赖性途径影响肾脏或 骨功能，特别关注是否有特定的效应器 这些途径与甲状旁腺素对骨骼的合成代谢作用有关。我们也会 验证甲状旁腺激素受体抑制软骨细胞增殖的假说 通过刺激AC不依赖的机制来促进生长板软骨的生长。 这些体外/体内分析的结果将澄清 对甲状旁腺素的反应是AC不依赖的。他们还可以让我们深入了解 优化甲状旁腺激素增加骨量的治疗措施， 并进一步加深我们对影响人体生长的疾病的理解 孩子们。

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 Aims III and IV complement Aims I and II in vivo, by assessing the phenotype of mice in whom both PTH1R genes has been replaced by the AC-defective mutant.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.