Dissecting the impact of Frizzled receptors in Wnt/β-catenin signaling of human mesenchymal stem cells
Dissecting the impact of Frizzled receptors in Wnt/β-catenin signaling of human mesenchymal stem cells
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DOI：
10.1515/hsz-2012-0186
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发表时间：
2012-12-01
影响因子：
3.7
通讯作者：
Neth, Peter
中科院分区：
文献类型：
--
作者：
Kolben, Thomas;Peroebner, Iris;Neth, Peter
Wnt/β-连环蛋白信号传导对于人间充质干细胞 (hMSC) 的自我更新、迁移/侵袭和分化的调节至关重要。由于关于卷曲受体 (Fzds) 作为 hMSC 中 Wnt 蛋白主要受体的功能的信息很少，我们首先进行了比较 Fzd mRNA 表达谱分析。 Fzd9 和 Fzd10 在 hMSC 中不表达。虽然 Fzd3 在 hMSC 中表达水平较低，但其他 Fzd 却表现出高表达率。 hMSCs 中 Wnt 信号的激活和抑制表明，Fzd1、Fzd6 和 Fzd7 的表达水平与 Wnt/β-catenin 激活状态呈正相关，而 Fzd8 则呈负相关。为了研究 Fzds 在 Wnt/β-连环蛋白信号传导中的功能相关性，在携带高度敏感的 TCF/LEF 报告基因系统（Gaussia 荧光素酶）的 hMSC 中进行了 RNA 干扰、异位表达研究和拯救方法。我们发现，Fzd1、Fzd5、Fzd7 和 Fzd8 主要参与 hMSC 的 Wnt/β-catenin 信号传导。此外，Fzd5 的敲低可以通过 Fzd7 的异位表达来补偿。相反，Fzd7 敲低 hMSC 中 Fzd5 的异位表达导致 Wnt/β-连环蛋白信号传导的挽救，表明 Fzd5 和 Fzd7 的功能冗余。
Wnt/beta-catenin signaling is of fundamental importance in the regulation of self-renewal, migration/invasion, and differentiation of human mesenchymal stem cells (hMSCs). Because little information is available about the function of Frizzled receptors (Fzds) as the main receptors of Wnt proteins in hMSCs, we first performed comparative Fzd mRNA expression profiling. Fzd9 and Fzd10 were not expressed in hMSCs. While Fzd3 was expressed at low levels in hMSCs, the other Fzds exhibited high expression rates. Activation and repression of Wnt signaling in hMSCs revealed that the expression levels of Fzd1, Fzd6, and Fzd7 are positively correlated with the Wnt/beta-catenin activation status, whereas Fzd8 exhibited an inverse relation. For studying the functional relevance of Fzds in Wnt/beta-catenin signaling, RNA interference, ectopic expression studies, and rescue approaches were performed in hMSCs carrying a highly sensitive TCF/LEF reporter gene system (Gaussia luciferase). We found that, Fzd1, Fzd5, Fzd7, and Fzd8 are largely involved in Wnt/beta-catenin signaling of hMSCs. Moreover, the knockdown of Fzd5 can be compensated by the ectopic expression of Fzd7. Conversely, the ectopic expression of Fzd5 in Fzd7-knockdown hMSCs resulted in a rescue of Wnt/beta-catenin signaling, pointing to a functional redundancy of Fzd5 and Fzd7.