Parathyroid Hormone and Osteoblast Mitogenesis

甲状旁腺激素和成骨细胞有丝分裂

• 批准号: 6820556
• 负责人: LOUIS M LUTTRELL
• 金额: $ 19.59万
• 依托单位: MEDICAL UNIVERSITY OF SOUTH CAROLINA
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-15 至 2006-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6820556
• 关键词: G protein coupled receptor kinase; SDS polyacrylamide gel electrophoresis; arrestins; autocrine; bone metabolism; cell differentiation; cell growth regulation; cell proliferation; confocal scanning microscopy; epidermal growth factor; genetically modified animals; hormone receptor; hormone regulation /control mechanism; immunoaffinity chromatography; laboratory mouse; metalloendopeptidases; mitogen activated protein kinase; osteoblasts; paracrine; parathyroid hormones; phosphorylation; physiologic bone resorption; polymerase chain reaction; prostaglandin receptor; receptor coupling; western blottings

DESCRIPTION (provided by applicant): Osteoblasts regulate the deposition of bone matrix protein and its subsequent mineralization. In situ, regulation of osteoblast proliferation, differentiation and function occurs via the complex interplay of extracellular signals mediated by steroid hormone and vitamin D receptors, receptor tyrosine kinases, and G protein-coupled receptors (GPCRs), such as those for parathyroid hormone (PTH) and prostaglandins. While it is clear that GPCRs transmit signals that are critical for the regulation of osteoblast metabolism, their significance as potential regulators of osteoblast growth and differentiation has only recently been appreciated. The broad goal of this research proposal is to determine how GPCRs regulate the growth and differentiation of osteoblasts through activation of the ERK mitogen-activated protein kinase (MAP) cascade, a key regulatory pathway in terms of both cell proliferation and differentiation. We provide preliminary data that demonstrate that GPCRs employ two novel mechanisms to direct the temporal and spatial activation of MAP kinases. First, matrix metalloprotease-mediated ectodomain shedding causes the release of autocrine ligands that induce "transactivation" of epidermal growth factor receptors (EGFRs). Second, beta-arrestins, proteins which bind to agonist-occupied GPCRs and uncouple them from their cognate G proteins, function as scaffolds for the component kinases of the ERK cascade and lead to the targeted activation of MAP kinase within specific cellular compartments. The first Aim of this proposal is to characterize the molecular mechanisms whereby PTH and prostaglandin receptors regulate the activity of MAP kinase cascades in osteoblasts. The second Aim is to determine the role of EGFR and beta-arrestin-dependent signals in regulating osteoblast proliferation, differentiation, and matrix production in vitro. These studies will employ osteoblastic cell lines and primary cultures of osteoblasts from mice in which EGFR or beta-arrestin function has been selectively inhibited. The third Aim of the proposal is to determine the role of EGFR and beta-arrestin-dependent signals in the control of anabolic bone metabolism by PTH in vivo. These studies will employ transgenic mouse models, in which beta-arrestins have been knocked out by homologous recombination or EGFR function has been impaired through osteoblast-specific expression of a dominant inhibitory mutant EGFR. By increasing our understanding of the mechanisms of GPCR signaling in bone, these studies may permit the rational development of safe strategies for employing PTH analogues to modulate osteoblast number and/or function.

描述(申请人提供)：成骨细胞调节 骨基质蛋白及其后续矿化。就地监管 成骨细胞的增殖、分化和功能是通过复合体发生的。 类固醇激素和维生素D介导的细胞外信号的相互作用 受体、受体酪氨酸激酶和G蛋白偶联受体(GPCRs)， 如甲状旁腺激素(PTH)和前列腺素。虽然它是 明确GPCR传递对监管至关重要的信号 成骨细胞代谢及其作为成骨细胞潜在调节因子的意义 增长和差异化直到最近才受到重视。总的目标是 这项研究的建议是确定GPCRs如何调节增长和 ERK丝裂原激活对成骨细胞分化的影响 蛋白激酶(MAP)级联，这是两种细胞的关键调控途径 增殖分化。我们提供的初步数据表明 GPCRs使用了两种新的机制来指导时间和空间 MAP激酶的激活。第一，基质金属蛋白酶介导的胞外结构域 脱落导致自分泌配体的释放，从而导致“反式激活”。 表皮生长因子受体(EGFR)。第二，β-阻滞剂，蛋白质 它们与激动剂占据的GPCRs结合，并将它们与其同源G解偶联 蛋白质，作为ERK级联组成蛋白激酶的支架 并导致特定细胞内MAP激酶的靶向激活 车厢。这项提议的第一个目标是描述分子 甲状旁腺激素和前列腺素受体调节成骨细胞MAP激活级联反应的机制。第二个目标是确定EGFR的作用 以及调控成骨细胞增殖的β-arrestin依赖信号， 分化，体外产生基质。这些研究将使用 成骨细胞系和小鼠成骨细胞的原代培养 EGFR或β-arrestin功能被选择性地抑制。第三个目标是 该提议是为了确定EGFR和β-arrestin依赖的作用 甲状旁腺素在体内调控骨合成代谢的信号。这些 研究将使用转基因小鼠模型，在该模型中，β-抑制素已被 被同源重组敲除或EGFR功能受损 通过成骨细胞特异性表达显性抑制突变体EGFR。通过 加深了我们对骨骼中gpr信号机制的理解，这些 研究可能会允许合理地制定安全策略来使用 甲状旁腺素类似物调节成骨细胞数量和/或功能。