Sequential Activation and Inactivation of Dishevelled in the Wnt/β-Catenin Pathway by Casein Kinases
Sequential Activation and Inactivation of Dishevelled in the Wnt/β-Catenin Pathway by Casein Kinases
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DOI：
10.1074/jbc.m110.169870
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发表时间：
2011-03-25
影响因子：
4.8
通讯作者：
Bryja, Vitezslav
中科院分区：
文献类型：
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作者：
Bernatik, Ondrej;Ganji, Ranjani Sri;Bryja, Vitezslav
disheveled （Dvl）是Wnt/ β -连环蛋白信号通路的关键组成部分。Dvl可以多聚形成动态蛋白聚集体，这是激活下游信号所必需的。在wnt激活后，Dvl被磷酸化，从而产生磷酸化移位（PS）的Dvl。Wnt/ β -连环蛋白信号通路中Dvl的激活和Wnt诱导的PS-Dvl的形成都依赖于酪蛋白激酶1 (CK1) δ /epsilon活性。然而，无论激活的Wnt是否触发Wnt/ β -catenin通路，CK1的过表达都会溶解Dvl聚集体和内源性PS-Dvl形成。结合使用功能获得、功能丧失和结构域映射方法，我们试图解决CK1 epsilon在Dvl生物学中作用的差异。我们分析了CK1 δ /epsilon和另外两个Dvl激酶CK2和PAR1在Wnt/ β -catenin通路中的相互作用。我们发现CK2作为一种组成激酶，其活性是CK1 epsilon进一步作用所必需的。此外，我们证明CK1 epsilon磷酸化的两个结果在空间和功能上是分离的；首先，CK1 epsilon介导的TCF/ lef驱动转录的诱导（与Axin1的动态募集相关）是通过Dvl中富含pdz -脯氨酸的区域介导的。其次，CK1 epsilon介导的PS-Dvl的形成是由Dvl3 C末端介导的。此外，我们用几种方法证明了PS-Dvl与其他dvl的聚合能力下降，因此可以作为非活性信号传导中间体。我们提出了一个Wnt/ β -catenin通路中Dvl激活的多步骤和多激酶模型，该模型揭示了一个内置的去激活机制，该机制是通过CK1 δ /epsilon激活Dvl磷酸化触发的。
Dishevelled (Dvl) is a key component in the Wnt/beta-catenin signaling pathway. Dvl can multimerize to form dynamic protein aggregates, which are required for the activation of downstream signaling. Upon pathway activation by Wnts, Dvl becomes phosphorylated to yield phosphorylated and shifted (PS) Dvl. Both activation of Dvl in Wnt/beta-catenin signaling and Wnt-induced PS-Dvl formation are dependent on casein kinase 1 (CK1) delta/epsilon activity. However, the overexpression of CK1 was shown to dissolve Dvl aggregates, and endogenous PS-Dvl forms irrespective of whether or not the activating Wnt triggers the Wnt/beta-catenin pathway. Using a combination of gain-of-function, loss-of-function, and domain mapping approaches, we attempted to solve this discrepancy regarding the role of CK1 epsilon in Dvl biology. We analyzed mutual interaction of CK1 delta/epsilon and two other Dvl kinases, CK2 and PAR1, in the Wnt/beta-catenin pathway. We show that CK2 acts as a constitutive kinase whose activity is required for the further action of CK1 epsilon. Furthermore, we demonstrate that the two consequences of CK1 epsilon phosphorylation are separated both spatially and functionally; first, CK1 epsilon-mediated induction of TCF/LEF-driven transcription (associated with dynamic recruitment of Axin1) is mediated via a PDZ-proline-rich region of Dvl. Second, CK1 epsilon-mediated formation of PS-Dvl is mediated by the Dvl3 C terminus. Furthermore, we demonstrate with several methods that PS-Dvl has decreased ability to polymerize with other Dvls and could, thus, act as the inactive signaling intermediate. We propose a multistep and multikinase model for Dvl activation in the Wnt/beta-catenin pathway that uncovers a built-in de-activation mechanism that is triggered by activating phosphorylation of Dvl by CK1 delta/epsilon.