Parathyroid hormone activates phosphoinositide 3-kinase-Akt-Bad cascade in osteoblast-like cells.
Parathyroid hormone activates phosphoinositide 3-kinase-Akt-Bad cascade in osteoblast-like cells.
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DOI：
10.1016/j.bone.2006.09.002
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发表时间：
2007-02
期刊：
影响因子：
4.1
通讯作者：
Takuya Yamamoto;F. Kambe;Xia Cao;Xiuli Lu;N. Ishiguro;H. Seo
中科院分区：
文献类型：
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作者：
Takuya Yamamoto;F. Kambe;Xia Cao;Xiuli Lu;N. Ishiguro;H. Seo
为了了解甲状旁腺激素 (PTH) 对骨合成代谢作用的分子基础，研究了 PTH 对成骨细胞样细胞的抗凋亡作用。由于 Akt 是细胞存活的关键蛋白激酶，因此我们重点关注 Akt 可能参与 PTH 的抗凋亡作用。用 PTH 处理无血清培养的人成骨细胞样 MG-63 细胞。 Western blot 分析显示，PTH 快速磷酸化 Akt 并诱导其核转位。 PTH 也会增加促凋亡蛋白 Bad 的磷酸化，导致其失活。在其他成骨细胞系 SaOS-2 和 ROS 17/2.8 中也检测到了 Akt 的 PTH 依赖性激活。用磷酸肌醇 3-激酶 (PI3K) 抑制剂、渥曼青霉素或 LY294002 之一预处理 MG-63 细胞可防止 Akt 和 Bad 磷酸化。此外，免疫共沉淀分析表明，PTH 受体（PTH-1R）以 PTH 依赖性方式直接与 PI3K 的调节亚基 p85 相互作用。血清停药诱导MG-63细胞凋亡，PTH阻止细胞凋亡，而PI3K抑制剂可抑制细胞凋亡。这些结果证明存在由 PTH-1R、PI3K、Akt 和 Bad 组成的新型 PTH/PTH 受体信号级联，并且该级联可以作为成骨细胞样细胞中的抗凋亡信号传导途径。
To understand the molecular basis underlying the anabolic action of parathyroid hormone (PTH) on bone, the anti-apoptotic action of PTH on osteoblast-like cells was investigated. Since Akt is a key protein kinase for cell survival, we focused on a possible involvement of Akt in the anti-apoptotic action of PTH. Human osteoblast-like MG-63 cells cultured without serum were treated with PTH. Western blot analysis revealed that PTH rapidly phosphorylated Akt and induced its nuclear translocation. The phosphorylation of pro-apoptotic protein Bad was also increased by PTH, leading to its inactivation. The PTH-dependent activation of Akt was also detected in other osteoblastic cell lines, SaOS-2 and ROS 17/2.8. The pretreatment of MG-63 cells with either one of inhibitors for phosphoinositide 3-kinase (PI3K), wortmannin or LY294002 prevented Akt and Bad phosphorylation. Furthermore, co-immunoprecipitation analysis revealed that PTH receptor (PTH-1R) directly interacted with p85, a regulatory subunit of PI3K, in a PTH-dependent manner. Serum withdrawal induced the apoptosis of MG-63 cells, and PTH prevented the apoptosis, which was inhibited by PI3K inhibitors. These results demonstrate the presence of a novel PTH/PTH receptor signaling cascade consisting of PTH-1R, PI3K, Akt and Bad and that this cascade can work as an anti-apoptotic signaling pathway in osteoblast-like cells.