The Effects of Dickkopf-4 on the Proliferation, Differentiation, and Apoptosis of Osteoblasts
The Effects of Dickkopf-4 on the Proliferation, Differentiation, and Apoptosis of Osteoblasts
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DOI：
10.1210/en.2013-1387
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发表时间：
2013-12-01
期刊：
影响因子：
4.8
通讯作者：
Kubota, Toshiro
中科院分区：
文献类型：
--
作者：
Hiramitsu, Shiro;Terauchi, Masakazu;Kubota, Toshiro
Dickkopf蛋白家族由四个成员（Dkk 1、Dkk 2、Dkk 3、Dkk 4）组成，已知其调节Wnt/β-连环蛋白信号传导，其在骨形成期间被激活。虽然Dkk 1对Wnt/β-连环蛋白信号传导的影响已经得到了很好的研究，但对Dkk 4的影响知之甚少。因此，为了评估Dkk 4在成骨细胞发生中的作用，我们使用小鼠成骨细胞系MC 3 T3-E1，其中Dkk 4表达被小干扰RNA敲低抑制。我们的研究结果表明，Dkk 4表达的抑制促进成骨细胞的增殖和分化，抑制凋亡。在碱性磷酸酶集落形成单位测定中，Dkk 4基因敲除细胞的碱性磷酸酶活性显著高于Dkk 1基因敲除细胞。Dkk 4表达的降低也导致β-连环蛋白水平、β-连环蛋白/T细胞因子活性和Wnt靶基因的上调。相反，在MC 3 T3-E1细胞中过表达Dkk 4导致成骨细胞分化的抑制。我们的研究结果表明，Dkk 4通过Wnt/beta-catenin信号传导作为成骨细胞生成的抑制剂发挥作用，为Wnt/beta-catenin信号传导和Dkk 4在骨形成中的关系提供了新的见解。
The Dickkopf family of proteins is comprised of four members (Dkk1, Dkk2, Dkk3, Dkk4) that are known to modulate Wnt/beta-catenin signaling, which is activated during bone formation. Although the effects of Dkk1 on Wnt/beta-catenin signaling have been well studied, little is known about the effects of Dkk4. Therefore, to evaluate the role of Dkk4 in osteoblastogenesis, we used the mouse osteoblastic cell line MC3T3-E1, in which Dkk4 expression was suppressed by small interfering RNA knockdown. Our results showed that the suppression of Dkk4 expression promoted osteoblast proliferation and differentiation and suppressed apoptosis. In colony-forming unit alkaline phosphatase assay, Dkk4 knockdown cells possessed markedly higher alkaline phosphatase activity compared with Dkk1 knockdown cells. Reduced Dkk4 expression also led to the up-regulation of beta-catenin levels, beta-catenin/T cell factor activity, and Wnt-target genes. In contrast, overexpression of Dkk4 in MC3T3-E1 cells led to inhibition of osteoblast differentiation. Our findings reveal that Dkk4 functions as an inhibitor of osteoblastogenesis through Wnt/beta-catenin signaling, providing new insights into the relationship between Wnt/beta-catenin signaling and Dkk4 in bone formation.