Wwp2 mediates Oct4 ubiquitination and its own auto-ubiquitination in a dosage-dependent manner
Wwp2 mediates Oct4 ubiquitination and its own auto-ubiquitination in a dosage-dependent manner
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Wwp2 以剂量依赖性方式介导 Oct4 泛素化及其自身的自动泛素化
DOI：
10.1038/cr.2009.136
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发表时间：
2010-03-01
期刊：
影响因子：
44.1
通讯作者：
Jin, Ying
中科院分区：
文献类型：
--
作者：
Liao, Bing;Jin, Ying
转录因子Oct4在维持胚胎干细胞(ESCs)的多能性和控制谱系承诺方面发挥重要作用。我们先前的研究表明，WWP2是一种小鼠Hect-type E3泛素连接酶，它泛素化Oct4并促进其在异源系统中的降解。然而，WWP2在调节内源Oct4蛋白水平中的作用以及WWP2功能的分子特征尚未确定。在这里，我们报道WWP2在胚胎癌细胞分化过程中的Oct4泛素化和降解过程中发挥重要作用，尽管它似乎不影响未分化的胚胎癌细胞和ESCs中Oct4的蛋白水平。重要的是，通过特异的RNA干扰抑制WWP2的表达会提高Oct4的蛋白水平，导致维甲酸诱导的分化相关标记基因的激活减弱。机制上，WWP2通过赖氨酸63连接以剂量依赖的方式催化Oct4多泛素化。有趣的是，WWP2也以类似的方式调节自己的连接酶活性。此外，WWP2的自动泛素化是通过分子内机制发生的。综上所述，这些结果证明了WWP2在ECC分化过程中控制内源性Oct4蛋白水平的关键作用，并提示了一种有趣的调节E3泛素连接酶WWP2催化活性的有趣的剂量依赖机制。
Transcription factor Oct4 plays critical roles in maintaining pluripotency and controlling lineage commitment of embryonic stem cells (ESCs). Our previous study indicates that Wwp2, a mouse HECT-type E3 ubiquitin ligase, ubiquitinates Oct4 and promotes its degradation in a heterologous system. However, roles of Wwp2 in regulating endogenous Oct4 protein levels as well as molecular characteristics of the function of Wwp2 have not been determined. Here, we report that Wwp2 plays an important role in Oct4 ubiquitination and degradation during differentiation of embryonal carcinoma cells (ECCs), although it does not appear to affect Oct4 protein levels in the undifferentiated ECCs and ESCs. Importantly, inhibition of Wwp2 expression by specific RNA interference elevates the Oct4 protein level, leading to attenuation in retinoid acid-induced activation of differentiation-related marker genes. Mechanistically, Wwp2 catalyzes Oct4 poly-ubiquitination via the lysine 63 linkage in a dosage-dependent manner. Interestingly, Wwp2 also regulates its own ligase activity in a similar manner. Moreover, auto-ubiquitination of Wwp2 occurs through an intra-molecular mechanism. Taken together, these results demonstrate a crucial role of Wwp2 in controlling endogenous Oct4 protein levels during differentiation processes of ECCs and suggest an interesting dosage-dependent mechanism for regulating the catalytic activity of the E3 ubiquitin ligase, Wwp2.