Department of Orthopaedics, Shengjing Hospital of China Medical University, Sanhao Street 36, Heping District, Shenyang 110004, China.
Cell Biochem Biophys. 2012 Dec;64(3):169-76. doi: 10.1007/s12013-012-9369-7.
It has been shown that hedgehog (Hh) signaling plays an important role during bone development. However, the mechanism(s) by which Hh stimulates osteoblast differentiation are not fully elucidated. This study was performed to examine if Sonic hedgehog (Shh) affects osteoblast differentiation in osteoblastic MC3T3-E1 cells and determine the exact role of osterix (Osx) involved in Hh-induced osteoblast differentiation. Our real-time RT-PCR result shows that Shh significantly induced osteoblast differentiation by up-regulation of osteocalcin, alkaline phosphatase, bone sialoprotein, Type I collagen, runt-related transcription factor 2 (Runx2), and Osx RNA expression in MC3T3-E1 cells. ALP protein activity, Osx protein expression, as well as Osx promoter activity was also enhanced by Shh treatment in cell culture. Interestingly, Shh-induced Osx up-regulation was only slightly affected by knocking down Runx2 using siRNA in cells within 3 days of culture, however, knocking down Osx expression in cells totally blocked Shh-induced osteoblast differentiation. These findings demonstrate for the first time that Shh stimulates early osteoblast differentiation mainly through up-regulation of the expression of Osx in osteoblastic MC3T3-E1 cells in both Runx2-dependent and Runx2-independent manner.
已经表明 hedgehog（Hh）信号在骨骼发育过程中起着重要作用。然而，Hh 刺激成骨细胞分化的机制尚不完全清楚。本研究旨在探讨 Sonic hedgehog（Shh）是否影响成骨细胞分化，并确定 osterix（Osx）在 Hh 诱导的成骨细胞分化中所扮演的具体角色。我们的实时 RT-PCR 结果表明，Shh 通过上调成骨细胞 MC3T3-E1 细胞中骨钙素、碱性磷酸酶、骨涎蛋白、I 型胶原、成骨转录因子 2（Runx2）和 Osx RNA 的表达，显著诱导成骨细胞分化。Shh 处理还增强了细胞培养中 ALP 蛋白活性、Osx 蛋白表达和 Osx 启动子活性。有趣的是，在培养 3 天内，用 siRNA 敲低 Runx2 对 Shh 诱导的 Osx 上调的影响很小，但敲低细胞中的 Osx 表达则完全阻断了 Shh 诱导的成骨细胞分化。这些发现首次表明，Shh 通过上调成骨细胞 MC3T3-E1 细胞中 Osx 的表达，以依赖和不依赖于 Runx2 的方式刺激早期成骨细胞分化。
