Characterization of Dkk1 gene regulation by the osteoblast-specific transcription factor Osx.
Characterization of Dkk1 gene regulation by the osteoblast-specific transcription factor Osx.
复制标题
成骨细胞特异性转录因子OSX对DKK1基因调节的表征。
DOI：
10.1016/j.bbrc.2012.03.073
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发表时间：
2012-04-20
影响因子：
3.1
通讯作者：
de Crombrugghe B
中科院分区：
文献类型：
--
作者：
Zhang C;Dai H;de Crombrugghe B
骨形成是一个发育过程，涉及间充质干细胞向成骨细胞的分化。Osterix（Osx）是一种成骨细胞特异性转录因子，在骨形成和成骨细胞分化中起重要作用。Osx抑制Wnt信号通路的研究为骨形成的反馈调控机制提供了新的概念。Wnt拮抗剂Dickkopf- 1（Dkk 1）在骨骼发育和骨重建中起重要作用。Osx已被证明可以激活Dkk 1启动子;然而，Osx调控Dkk 1表达的详细机制尚未完全了解。在本研究中，定量实时RT-PCR结果表明，Dkk 1表达在Osx无效的小鼠胚胎的颅骨在E15.5和E18.5两个不同的点下调。Osx过表达可上调Tet-off稳定的C2 C12细胞系中Dkk 1的表达。通过siRNA抑制Osx表达导致成骨细胞中Dkk 1的下调。这些数据表明Osx可能直接靶向Dkk 1。为了确定Osx激活Dkk 1启动子的最小区域，我们构建了一系列Dkk 1启动子缺失突变体，并通过瞬时转染实验将最小区域缩小到近250 bp。结果表明，在Dkk 1启动子的这个最小区域内的两个富含GC的结合位点是Osx激活Dkk 1启动子所必需的。重要的是，进行了定量染色质免疫沉淀（ChIP）测定，以显示内源性Osx与原代成骨细胞中的天然Dkk 1启动子相关。综上所述，这些发现支持了我们的假设，即Dkk 1是Osx的直接靶点。
Bone formation is a developmental process involving the differentiation of mesenchymal stem cells to osteoblasts. Osterix (Osx) is an osteoblast-specific transcription factor required for bone formation and osteoblast differentiation. Previous observation that Osx inhibits Wnt signaling pathway provides a novel concept of feedback control mechanisms involved in bone formation. Wnt antagonist Dickkopf- 1(Dkk1) plays an important role on skeletal development and bone remodeling. Osx has been shown to activate the Dkk1 promoter; however, the detailed mechanism of Osx regulation on Dkk1 expression is not fully understood. In this study, quantitative real-time RT-PCR results demonstrated that Dkk1 expression was downregulated in Osx-null calvaria at two different points of E15.5 and E18.5 in mice embryos. Overexpression of Osx resulted in upregulation of Dkk1 expression in Tet-off stable C2C12 cell line. Inhibition of Osx expression by siRNA led to downregulation of Dkk1 in osteoblasts. These data suggest that Osx may target Dkk1 directly. To define minimal region of Dkk1 promoter activated by Osx, we made a series of deletion mutants of Dkk1 promoter constructs, and narrowed down the minimal region to the proximal 250bp by transient transfection assay. It was shown that two GC-rich binding sites within this minimal region of Dkk1 promoter were required for the Dkk1 promoter activation by Osx. Importantly, quantitative Chromatin immunoprecipitation (ChIP) assays were performed to show that endogenous Osx associated with native Dkk1 promoter in primary osteoblasts. Taken together, these findings support our hypothesis that Dkk1 is a direct target of Osx.
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DOI：
10.1007/s11420-007-9072-1
发表时间：
2008-02-01
期刊：
HSS journal : the musculoskeletal journal of Hospital for Special Surgery
影响因子：
--
作者：
Issack, Paul S;Helfet, David L;Lane, Joseph M
通讯作者：
Lane, Joseph M
影响因子：
2.7
作者：
Franceschi, Renny T.;Ge, Chunxi;Jiang, Di
通讯作者：
Jiang, Di
影响因子：
64.5
作者：
Nakashima, K;Zhou, X;de Crombrugghe, B
通讯作者：
de Crombrugghe, B
影响因子：
4.8
作者：
Zhang, C;Dowd, DR;MacDonald, PN
通讯作者：
MacDonald, PN
影响因子：
6.2
作者：
Babij, P;Zhao, WG;Bex, F
通讯作者：
Bex, F