PTH STIMULATED BONE FORMATION

PTH 刺激骨形成

• 批准号: 6090288
• 负责人: Robert L Jilka
• 金额: $ 29.63万
• 依托单位: UNIV OF ARKANSAS FOR MED SCIS
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-03-08 至 2005-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6090288
• 关键词: 3T3 cells; apoptosis; bone density; bone development; cell growth regulation; cell population study; densitometry; genetically modified animals; green fluorescent proteins; hormone regulation /control mechanism; laboratory mouse; metalloendopeptidases; osteoblasts; osteogenesis; parathyroid hormones; phosphorylation; protein kinase

To achieve the long sought therapeutic goal of rebuilding bone in osteopenic states, osteoblast number must be increased by stimulating their differentiation from local progenitors and/or extending osteoblast life span. We recently obtained evidence that the increased osteoblast number, bone formation rate, and bone mass caused by intermittent administration of parathyroid hormone (PTH) to mice is due to an anti- apoptotic effect of the hormone on osteoblast. Moreover, the contribution of increased osteoblast or lining cell activation-previously proposed to mediate the anabolic effect of PTH- was minimal if any. In vitro studies indicated that PTH inhibited the apoptosis of osteoblastic cells induced by etoposide via cAMP-mediated intracellular signaling events, and the PTH inhibited osteoblast apoptosis caused by loss of integrin signaling events; and that PTH inhibited osteoblast apoptosis caused by loss of integrin signaling, i.e. anoikis. We propose the hypothesis that the anabolic effect of PTH on the skeleton due to a reduction in the prevalence of osteoblast apoptosis; and that this effect is mediated by inhibition of the osteoblast anoikis that occurs during bone formation. To dissect the relative contribution of osteoblast apoptosis prevention, increased osteoblast differentiation, and lining cell activation, to the anabolic effect of PTH, we will use OG2-Hsv-tk transgenic mice in which the number of osteoblast progenitors and osteoblasts can be controlled with ganciclovir. The molecular mechanism by which PTH inhibits osteoblast apoptosis will be studied by focusing on PTH-stimulated processes that have the potential of replacing anti-apoptotic signals that are lost during anoikis. The include cAMP-dependent intracellular signaling pathways; the generation of new integrin-binding molecules via pericellular matrix degradation by matrix metalloproteinases; and the production of anti- apoptotic growth factors including IL-6 type cytokines and insulin-like growth factors. The results of this work will set the stage for approaching the long-term goal of determining the in vivo relevance of critical PTH- induced anti-apoptotic pathways for stimulation of bone formation, and elucidating the role of anoikis in determining osteoblast life span, using appropriate transgenic mice.

为了实现在骨质减少状态下重建骨骼的长期以来的治疗目标，必须通过刺激其与局部祖细胞的分化和/或延长成骨细胞寿命来增加成骨细胞数量。我们最近获得了证据，表明成骨细胞数量增加，骨形成率和由甲状旁腺激素（PTH）施加给小鼠引起的骨量是由于激素对成骨细胞的抗凋亡作用。此外，如果有的话，提议介导PTH-的合成代谢效应的成骨细胞或内膜细胞激活增加的贡献是最小的。体外研究表明，PTH抑制了依托泊苷通过CAMP介导的细胞内信号传导事件诱导的成骨细胞的凋亡，而PTH抑制了由整联蛋白信号事件丧失引起的成骨细胞凋亡。 PTH抑制了整联蛋白信号传导丧失引起的成骨细胞凋亡，即Anoikis。我们提出了以下假设：由于成骨细胞凋亡的患病率降低，PTH对骨骼的合成代谢作用对骨骼的骨骼效果。并且这种作用是通过抑制骨形成过程中发生的成骨细胞厌氧菌的介导的。为了剖析成骨细胞凋亡预防的相对贡献，成骨细胞的分化增加以及细胞活化对PTH的合成代谢作用，我们将使用OG2-HSV-TK TK TKNEC转基因小鼠，其中成骨细胞的成骨细胞的数量和成骨细胞的数量可以与Ganciclovir一起控制。 PTH抑制成骨细胞细胞凋亡的分子机制将通过关注PTH刺激的过程来研究，而PTH刺激的过程有可能替代在AnoikiS期间丢失的抗凋亡信号。包括依赖cAMP的细胞内信号通路；通过基质金属蛋白酶通过周围的细胞基质降解而产生新的整联蛋白结合分子；以及包括IL-6型细胞因子和胰岛素样生长因子在内的抗凋亡生长因子的产生。这项工作的结果将为实现长期目标确定临界PTH诱导的抗凋亡途径的体内相关性以刺激骨形成的体内相关性，并阐明使用适当的转基因小鼠，阐明了Anoikis在确定成骨细胞寿命中的作用。