Differential activation of the calcium/protein kinase C and the canonical β-catenin pathway by Wnt1 and Wnt7a produces opposite effects on cell proliferation in PC12 cells
Differential activation of the calcium/protein kinase C and the canonical β-catenin pathway by Wnt1 and Wnt7a produces opposite effects on cell proliferation in PC12 cells
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DOI：
10.1111/j.1471-4159.2007.05111.x
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发表时间：
2008-03-01
影响因子：
4.7
通讯作者：
Nicoletti, Ferdinando
中科院分区：
文献类型：
--
作者：
Spinsanti, Paola;De Vita, Teresa;Nicoletti, Ferdinando
我们研究了Wnt 1和Wnt 7a对使用未分化的PC 12细胞的细胞增殖的影响，所述未分化的PC 12细胞来源于神经嵴并且被广泛用作神经元细胞模型。Wnt 1的异源表达增强了PC 12细胞[H-3]胸苷掺入和cyclin D1和cyclin E的表达。在表达Wnt 7a的PC 12细胞中观察到相反的效果。为了寻找Wnt 1和Wnt 7a对PC 12细胞增殖的相反作用的机制，我们通过将细胞与由T细胞淋巴增强子结合蛋白转录因子或钙激活转录因子NFAT控制的报告基因共转染来检测经典β-连环蛋白/T细胞淋巴增强子结合蛋白转录因子途径和“钙途径”的激活。Wnt 1和Wnt 7a激活了这两条途径，但程度不同。Wnt 1优先激活钙通道，而Wnt 7a主要激活经典钙通道。药理学抑制蛋白激酶C，这是钙通道的一个组成部分，废除了Wnt 1诱导的细胞增殖的增加，而不影响Wnt 7a的抗增殖作用。相反，Wnt 7a的作用被锂离子封闭，这模拟了经典途径的激活，并且在很大程度上被Dickkopf-1降低，Dickkopf-1作为经典途径的抑制剂。此外，β-连环蛋白的组成型活性突变体的表达有效地激活了经典的Wnt途径，并减少了[H-3]胸苷掺入。这些数据挑战了经典Wnt途径总是支持细胞生长的观点，并表明至少在PC 12细胞中，细胞增殖受钙/蛋白激酶C途径和经典途径之间的平衡调节。
We examined the effect of Wnt1 and Wnt7a on cell proliferation using undifferentiated PC12 cells, which originate from the neural crest and are widely employed as a neuronal cell model. Heterologous expression of Wnt1 enhanced [H-3]thymidine incorporation and expression of cyclin D1 and cylin E in PC12 cells. Opposite effects were observed in PC12 cells expressing Wnt7a. Searching for the mechanisms underlying the opposite effects of Wnt1 and Wnt7a on PC12 cell proliferation, we examined the activation of the canonical beta-catenin/T-cell-lymphoid enhancer-binding protein transcription factor pathway and the 'calcium pathway' by co-transfecting the cells with a reporter gene controlled by either T-cell-lymphoid enhancer-binding protein transcription factor or the calcium-activated transcription factor, NFAT. Wnt1 and Wnt7a activated both pathways, but to a different extent. While Wnt1 preferentially activated the calcium pathway, Wnt7a mainly activated the canonical pathway. Pharmacological inhibition of protein kinase C, which is a component of the calcium pathway, abrogated the increase in cell proliferation induced by Wnt1 without affecting the antiproliferative action of Wnt7a. The action of Wnt7a was instead occluded by lithium ions, which mimic the activation of the canonical pathway, and was largely reduced by Dickkopf-1, which acts as an inhibitor of the canonical pathway. In addition, expression of a constitutively active mutant of beta-catenin potently activated the canonical Wnt pathway and reduced [H-3]thymidine incorporation. These data challenge the view that the canonical Wnt pathway invariably supports cell growth and suggest that, at least in PC12 cells, cell proliferation is regulated by the balance between the calcium/protein kinase C pathway and the canonical pathway.