Downregulation of Wnt signaling by increased expression of Dickkopf-1 and-2 is a prerequisite for late-stage osteoblast differentiation of KS483 cells
Downregulation of Wnt signaling by increased expression of Dickkopf-1 and-2 is a prerequisite for late-stage osteoblast differentiation of KS483 cells
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DOI：
10.1359/jbmr.050614
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发表时间：
2005-10-01
影响因子：
6.2
通讯作者：
Karperien, M
中科院分区：
文献类型：
--
作者：
van der Horst, G;van der Wert, SM;Karperien, M
我们研究了Wnt/β-连环蛋白信号在成骨细胞分化的连续阶段中的作用。已经表明，成熟成骨细胞中的Wnt信号传导需要下调以使得能够形成矿化基质。使用RNA干扰，我们表明，这是，至少部分地，通过上调Wnt拮抗剂Dickkopf-1和-2。引言：Wnt信号在成骨细胞分化的启动中的作用已经得到了很好的研究。然而，在后期分化中的作用不太清楚。我们已经研究了Wnt/β-catenin信号在成骨细胞分化的连续阶段中的作用。材料和方法：我们处理小鼠骨髓和间充质干细胞样KS 483细胞与氯化锂或Wnt 3A在成骨细胞分化的几个阶段。此外，我们还建立了稳定的KS 483细胞系，沉默Wnt拮抗剂Dkk-1或Dkk-2。结果：LiCl激活Writ信号通路可抑制两种细胞中矿化骨基质的形成。而未分化的KS 483细胞通过诱导核0-连环蛋白易位响应Wnt 3A，分化的细胞不。这至少部分是通过在成骨细胞分化过程中上调Dkk-1和Dkk-2的表达来实现的。使用RNA干扰，我们发现Dkk-1在钝化BMP诱导的碱性磷酸酶（ALP）反应和矿化细胞中ALP（+）成骨细胞的转变中起着至关重要的作用。与此相反，Dkk-2在成骨细胞增殖和成骨细胞分化的起始中起作用：结论：我们的数据表明，Wnt信号在成熟的成骨细胞需要下调，使矿化骨基质的形成。Dkk-1和Dkk-2在成骨细胞分化中可能具有不同的功能。
We examined the role of Wnt/beta-catenin signaling in successive stages of osteoblast differentiation. It has been shown that Wnt signaling in mature osteoblasts needs to be downregulated to enable the formation of a mineralized matrix. Using RNA interference, we showed that this is, at least in part, accomplished by upregulation of the Wnt antagonists Dickkopf-1 and -2.Introduction: The role of Wnt signaling in the initiation of osteoblast differentiation has been well studied. However, the role during late-stage differentiation is less clear. We have examined the role of Wnt/beta-catenin signaling in successive stages of osteoblast differentiation.Materials and Methods: We treated murine bone marrow and mesenchymal stem cell-like KS483 cells with either LiCl or Wnt3A during several stages of osteoblast differentiation. In addition, we generated stable KS483 cell lines silencing either the Wnt antagonist Dkk-1 or -2.Results: Activation of Writ signaling by LiCl inhibits the formation of a mineralized bone matrix in both cell types. Whereas undifferentiated KS483 cells respond to Wnt3A by inducing nuclear 0-catenin translocation, differentiated cells do not. This is at least in part accomplished by upregulated expression of Dkk-1 and -2 during osteoblast differentiation. Using RNA interference, we showed that Dkk-1 plays a crucial role in blunting the BMP-induced alkaline phosphatase (ALP) response and in the transition of an ALP(+) osteoblast in a mineralizing cell. In contrast, Dkk-2 plays a role in osteoblast proliferation and the initiation of osteoblast differentiation.Conclusions: Our data suggest that Wnt signaling in maturing osteoblasts needs to be downregulated to enable the formation of a mineralized bone matrix. Furthermore, they suggest that Dkk-1 and Dkk-2 may have distinct functions in osteoblast differentiation.