G PROTEIN SIGNALING IN OSTEOBLASTS

成骨细胞中的 G 蛋白信号传导

• 批准号: 7564676
• 负责人: Robert Nissenson
• 金额: $ 32.19万
• 依托单位: NORTHERN CALIFORNIA INSTITUTE/RES/EDU
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7564676
• 关键词: Address; Agonist; Alleles; Apoptosis; Biology; Bone Development; Bone Marrow; Bone Resorption; Catalytic Domain; Cells; Complex; Doctor of Philosophy; Engineering; Event; Excision; Fluorides; G-Protein Signaling Pathway; G-Protein-Coupled Receptors; GTP-Binding Protein alpha Subunits, Gs; GTP-Binding Proteins; Genetic; Growth; Growth Factor; Homeostasis; Hormones; Knock-out; Lead; Ligands; Light; Link; Mechanics; Mediating; Mus; Nature; Osteoblasts; Osteogenesis; Osteoporosis; Pathway interactions; Pertussis Toxin; Physiological; Play; Regulation; Research Personnel; Role; Signal Pathway; Signal Transduction; Signaling Protein; Skeleton; Staging; Stimulus; Stromal Cells; Strontium; System; Testing; Transgenic Mice; bone; bone mass; calcium phosphate; in vivo; interest; loss of function; new therapeutic target; novel strategies; osteoblast differentiation; programs; receptor; response; skeletal; transcription factor

Extrinsic factors such as hormones, growth factors, and mechanical strain produce their effects on skeletal growth and remodeling via actions on osteoblasts. Accordingly, there is great interest in defining how specific intracellular signaling pathways mediate the effects of these factors in controlling osteoblast function. G protein signaling occurs in response to many skeletal stimuli, and the consequence of this signaling depends on the nature of the G protein; the temporal delivery of the signal; and the phenotypic state of the osteoblast. A clearer understanding of how calciotropic agents such as PTH elicit their complex effects in bone requires studies that address these issues directly in an in vivo context. In the present proposal, we will assess the role of Gs and Gi signaling in osteoblasts in mediating anabolic skeletal responses. In one approach, novel G protein-coupled receptors termed RASSLs will be targeted to osteoblasts in transgenic mice. RASSLs activate specific G protein pathways in response to administration of synthetic agonists. Activation of Gs- and Gi RASSLs will allow us to dissect the role of these pathways in skeletal responses. In a second approach, Gs and Gi function will be ablated in osteoblasts in vivo by cre-mediated excision of functional Gs-alpha alleles and by targeted expression of the catalytic subunit of pertussis toxin, respectively. We will determine the effects of ablating these signaling pathways on normal skeletal homeostasis and on the anabolic response to PTH. Mechanistic studies will be carried out to assess the effects of G protein signals on osteoblast proliferation and apoptosis in vivo and in bone marrow stromal cells (BMSCs) isolated from the transgenic mice. Convergence of G protein signals with two pathways recently shown to be essential for bone formation - the LRP/canonical wnt pathway and the recently identified RSK2/ATF4 pathway- will be explored in BMSCs. We propose to: 1) assess the role of osteoblast Gs and Gi signaling in the regulation of skeletal homeostasis in mature mice. We will determine the effects of regulated, intermittent Gs and Gi signaling in osteoblasts at different stages of differentiation; determine the skeletal effect of conditional knockout of Gs and Gi signaling; and assess the mechanisms by which manipulation of Gs and Gi signaling elicits these effects; and 2) determine the contribution of Gs and Gi signaling to the anabolic response to PTH and the mechanisms of these effects. These studies will shed new light on the control of bone formation and bone resorption by G protein signaling in osteoblasts at different stages of differentiation. They may also provide new links between G protein signals and anabolic effects in bone, thereby identifying new therapeutic targets for the treatment of osteoporosis. LAY DESCRIPTION: We will explore how activation of specific signals in bone-forming cells can lead to increases in bone mass. The results may lead to new approaches to the treatment of osteoporosis.

诸如激素，生长因子和机械应变之类的外在因子对骨骼的影响 通过对成骨细胞的作用进行生长和重塑。因此，定义如何 特定的细胞内信号通路介导了这些因素控制成骨细胞功能的影响。 G蛋白信号传导是响应许多骨骼刺激而发生的，并且该信号的结果 取决于G蛋白的性质；信号的时间传递；以及表型的状态 成骨细胞。对诸如PTH之类的钙化剂如何引起其复杂作用的更清晰了解 骨需要在体内直接解决这些问题的研究。在本提案中，我们 将评估GS和GI信号在成骨细胞中介导合成代谢骨骼反应中的作用。一个 方法，称为RASSL的新型G蛋白偶联受体将针对转基因的成骨细胞 老鼠。 RASSL响应合成激动剂的给药而激活特定的G蛋白途径。 GS和GI RASSL的激活将使我们能够剖析这些途径在骨骼反应中的作用。在 第二种方法将通过Cre介导的切除术在体内在成骨细胞中烧开GS和GI功能 功能性GS-Alpha等位基因和通过靶向百日咳毒素的催化亚基的靶向表达。 我们将确定消除这些信号通路对正常骨骼稳态的影响以及 对PTH的合成代谢响应。机械研究将进行评估G蛋白的影响 分离的成骨细胞增殖和凋亡的信号和骨髓基质细胞（BMSC）分离 来自转基因小鼠。 G蛋白信号与最近显示为两个途径的收敛性 骨形成必不可少的 - LRP/典型的Wnt途径和最近确定的RSK2/ATF4 路径 - 将在BMSC中探索。我们建议：1）评估成骨细胞GS和GI信号在 调节成熟小鼠骨骼稳态。我们将确定受调节的间歇性的影响 分化不同阶段的成骨细胞中的GS和GI信号传导；确定骨骼效应 GS和GI信号的有条件敲除；并评估操纵GS和的机制 GI信号引起这些影响； 2）确定GS和GI信号对合成代谢的贡献 对PTH的反应和这些作用的机制。这些研究将为控制 在分化的不同阶段，在成骨细胞中G蛋白信号传导的骨形成和骨吸收。 它们还可以在骨骼中提供G蛋白信号和合成代谢作用之间的新联系，从而确定 用于治疗骨质疏松症的新治疗靶标。 外表描述：我们将探讨如何激活骨形成细胞中特定信号 骨骼质量增加。结果可能会导致治疗骨质疏松症的新方法。