Role of GSK3beta in Osteoblast Cell Cycle, Differentiat*

GSK3beta 在成骨细胞周期、分化中的作用*

• 批准号: 6863762
• 负责人: ELISHEVA SMITH
• 金额: $ 8.13万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-03-15 至 2006-08-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6863762
• 关键词: biological signal transduction; biomarker; cadherins; cell cycle; cell differentiation; cell proliferation; flow cytometry; glucocorticoids; glycogen synthase; immunoprecipitation; inflammation; northern blottings; osteoblasts; osteoporosis; tissue /cell culture; transfection; western blottings

DESCRIPTION (provided by applicant): Osteoporosis is a major adverse effect of glucocorticoid (GC) treatment for the amelioration of symptoms of autoimmune and inflammatory diseases. The most important single mechanism contributing to bone loss in GC-treated patients is inhibition of osteoblastic bone formation. We recently identified a commitment stage during osteoblast differentiation in culture (the "cobblestone" stage) in which GC exert their inhibitory effect. During this stage, proliferation persists, but is regulated uniquely compared to control of the cell cycle prior to confluence. At this commitment stage, but not earlier, GC inhibit cell cycle progression and this inhibition is mediated by attenuation of the Ser9 inhibitory phosphorylation of Glycogen Synthase Kinase 3beta(GSKbeta). GSK3beta3 plays pivotal roles in cell proliferation and differentiation. It has been implicated in both the Wnt beta - catenin pathway and the growth factor-activated PI3 kinase/Akt pathway. Numerous studies demonstrated roles for growth factors such as IGF-I and FGF-2 in osteoblast differentiation, but the involvement of GSK3beta has not been sufficiently studied. Several recent reports suggest a role for Wnt signaling in osteoblast differentiation, but again the involvement of GSK3beta has not been tested. Thus, we propose to examine the role of GSK3beta in the osteoblast differentiation-related cell cycle, in the development of the osteoblast phenotype and in GC-mediated inhibition of these processes. In Specific Aim 1, we will examine the role that GSK3beta plays down stream of PI3 Kinase and Akt. In Specific Aim 2, we will examine the role that GSK3beta plays downstream of Wnt. In both Specific Aims, we will measure levels and activities of various components of each pathway in GC-treated versus non-treated osteoblast cultures. In addition, to map the step that is directly affected by GC, we will either augmnent or suppress signaling molecules in each pathway, and examine the effects on GSK3beta, the cell cycle as well as differentiation markers in GC-treated and non-treated cultures. These studies will shed light on novel aspects of osteoblast growth and differentiation, and how these processes are adversely affected by glucocorticoids.

描述（由申请人提供）：骨质疏松症是用于改善自身免疫性疾病和炎症性疾病症状的糖皮质激素（GC）治疗的主要副作用。导致 GC 治疗患者骨质流失的最重要的单一机制是抑制成骨细胞骨形成。我们最近确定了培养中成骨细胞分化过程中的一个定型阶段（“鹅卵石”阶段），在该阶段GC发挥其抑制作用。在此阶段，增殖持续存在，但与汇合前的细胞周期控制相比，增殖受到独特的调节。在这个定型阶段（但不是更早），GC 抑制细胞周期进程，这种抑制是通过减弱糖原合酶激酶 3beta (GSKbeta) 的 Ser9 抑制性磷酸化来介导的。 GSK3beta3 在细胞增殖和分化中发挥着关键作用。它与 Wnt β-连环蛋白途径和生长因子激活的 PI3 激酶/Akt 途径有关。大量研究证明了IGF-I和FGF-2等生长因子在成骨细胞分化中的作用，但GSK3β的参与尚未得到充分研究。最近的几份报告表明 Wnt 信号在成骨细胞分化中发挥作用，但 GSK3beta 的参与尚未得到测试。因此，我们建议检查 GSK3beta 在成骨细胞分化相关细胞周期、成骨细胞表型的发育以及 GC 介导的这些过程的抑制中的作用。在具体目标 1 中，我们将研究 GSK3beta 在 PI3 激酶和 Akt 下游发挥的作用。在具体目标 2 中，我们将研究 GSK3beta 在 Wnt 下游发挥的作用。在这两个具体目标中，我们将测量 GC 处理与未处理的成骨细胞培养物中每个途径的各种成分的水平和活性。此外，为了绘制直接受 GC 影响的步骤，我们将增强或抑制每个途径中的信号分子，并检查 GC 处理和未处理的培养物中对 GSK3beta、细胞周期以及分化标记物的影响。这些研究将揭示成骨细胞生长和分化的新方面，以及糖皮质激素如何对这些过程产生不利影响。