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首页> 外文期刊>Molecular and Cellular Biology >Laforin Negatively Regulates Cell Cycle Progression through Glycogen Synthase Kinase 3β-Dependent Mechanisms
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Laforin Negatively Regulates Cell Cycle Progression through Glycogen Synthase Kinase 3β-Dependent Mechanisms

机译:Laforin负调节糖原合酶激酶3β依赖机制的细胞周期进程。

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Glycogen synthase kinase 3β (GSK-3β) represses cell cycle progression by directly phosphorylating cyclin D1 and indirectly regulating cyclin D1 transcription by inhibiting Wnt signaling. Recently, we reported that the Epm2a-encoded laforin is a GSK-3β phosphatase and a tumor suppressor. The cellular mechanism for its tumor suppression remains unknown. Using ex vivo thymocytes and primary embryonic fibroblasts from Epm2a?/? mice, we show here a general function of laforin in the cell cycle regulation and repression of cyclin D1 expression. Moreover, targeted mutation of Epm2a increased the phosphorylation of Ser9 on GSK-3β while having no effect on the phosphorylation of Ser21 on GSK-3α. In the GSK-3β+/+ but not the GSK-3β?/? cells, Epm2a small interfering RNA significantly enhanced cell growth. Consistent with an increased level of cyclin D1, the phosphorylation of retinoblastoma protein (Rb) and the levels of Rb-E2F-regulated genes cyclin A, cyclin E, MCM3, and PCNA are also elevated. Inhibitors of GSK-3β selectively increased the cell growth of Epm2a+/+ but not of Epm2a?/? cells. Taken together, our data demonstrate that laforin is a selective phosphatase for GSK-3β and regulates cell cycle progression by GSK-3β-dependent mechanisms. These data provide a cellular basis for the tumor suppression activity of laforin.
机译:糖原合酶激酶3β(GSK-3β)通过直接磷酸化细胞周期蛋白D1并通过抑制Wnt信号间接调控细胞周期蛋白D1转录来抑制细胞周期进程。最近,我们报道了 Epm2a 编码的laforin是GSK-3β磷酸酶和一种肿瘤抑制因子。抑制肿瘤的细胞机制仍然未知。使用来自 Epm2a / 小鼠的离体胸腺细胞和原代成纤维细胞,我们在这里显示了laforin在细胞周期中调控和抑制cyclin D1的表达。而且, Epm2a 的靶向突变增加了GSK-3β上Ser9的磷酸化,而对GSK-3α上Ser21的磷酸化没有影响。在GSK-3β + / + 而不是GSK-3β?/?细胞中, Epm2a 小干扰RNA显着增强了细胞的生长。与细胞周期蛋白D1水平升高,视网膜母细胞瘤蛋白(Rb)磷酸化以及Rb-E2F调控基因 cyclin A cyclin E 的水平一致MCM3 PCNA 也会升高。 GSK-3β抑制剂选择性增加 Epm2a + / + 的细胞生长,但不增加 Epm2a 的细胞生长 / 单元格。两者合计,我们的数据表明,laforin是GSK-3β的选择性磷酸酶,并通过GSK-3β依赖性机制调节细胞周期进程。这些数据为laforin的肿瘤抑制活性提供了细胞基础。

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