中文摘要：

目的：研究内源性甲状旁腺激素（parathyroid hormone,PTH）是否通过Notch信号通路调控骨髓间充质干细胞向成骨细胞分化。方法：取8周龄PTH野生型（PTH＋/＋）和PTH基因敲除型（PTH-/-）小鼠各6只,分离培养小鼠骨髓间充质干细胞并向成骨细胞诱导分化。分别在诱导后的3、7、10、14 d,用Western blot方法检测Notch信号通路受体和配体的表达。在诱导后的3、7 d,检测细胞中碱性磷酸酶（alkaline phosphate,ALP）活性,用Western blot方法检测成骨指标runt相关转录因子2（runt-related transcription factor 2,Runx2）、骨钙素（osteocalcin,OCN）的表达。结果 ：在野生型组和PTH基因敲除组的小鼠骨髓间充质干细胞向成骨细胞诱导分化过程中,Notch信号通路的受体和配体以及各成骨指标上调。PTH基因敲除组中Notch信号通路配体Jagged1和受体Notch1表达明显低于野生型组,差异具有统计学意义（P〈0.01）。PTH基因敲除组中各成骨指标Runx2、OCN蛋白表达和ALP活性均低于野生型组。结论：内源性PTH缺失可能通过下调Notch信号通路Jagged1配体和Notch1受体的表达来抑制骨髓间充质干细胞向成骨细胞分化。

英文摘要：

Objective：To study whether parathyroid hormone regulates the differentiation of bone mesenchymal stem cells into osteoblasts through Notch signaling pathway. Methods：Six PTH＋ /＋and six PTH- /-mice of 8-week-old were used in this study. Bone mesenchymal stem cells obtained from mouse femurs were isolated and cultured,then osteogenic differentiation was induced. Western blot was performed to detect the expression of Notch signaling pathway at day 3,7,10,14. The alkaline phosphate（ALP）activity was detected to evaluate the early osteogentic differentiation at day 3 and 7. Western blot was performed to detect the expression of Runx2 and OCN proteins. Results：The receptor and ligand of Notch signal pathway and the osteogenic index was increased in the wild type group and PTH gene knockout group after osteogenic differentiation. The expression of Jagged1 and Notch1 protein in PTH gene knockout group was significantly lower than that of the wild type group（P〈0.01）. Compared with the wild type group,Runx2 and OCN protein levels were lower in PTH gene knockout group,with the same trends as ALP results. Conclusion：The deficiency of endogenous PTH inhibited the differentiation of bone marrow mesenchymal stem cells into osteoblasts,by reducing the expression of Notch1 and Jagged1 proteins.