Casein Kinase 1 Delta in Wnt Signaling and Beyond

我们确定了尤文瘤细胞对Wnt-3a的反应是形成神经突，并开始确定这种作用的机制。敲除非典型PKCiota也阻断Wnt-3a依赖性神经突生长。Wnt-3a刺激PKCi的磷酸化。Dvl 2与PKCi共免疫沉淀，当Dvl 2中的CK 1磷酸化位点被丙氨酸残基取代时，这种相互作用不会发生。这些结果表明，Dvl 2磷酸化CK 1所需的Dvl 2-PKCi结合，这反过来可能是必要的神经突生长。这项工作意义重大，不仅因为它提供了有关神经突形成机制的见解。参与神经突生长的许多因素在其他情况下有助于细胞极性，例如形成对细胞迁移至关重要的细胞延伸。抑制CK 1d阻断hTERT-RPE和mIMCD 3细胞中的初级纤毛发生。小鼠胚胎成纤维细胞和视网膜细胞CK 1d null小鼠也表现出纤毛发生缺陷。干扰CK 1d表达或催化活性破坏了参与纤毛转运的几种蛋白质的核小体周围或纤毛分布，包括Rab 11 a、Rab 8a、CEP 290、PCM 1和多囊蛋白-2，以及AKAP 450的高尔基体分布。与其结合伴侣AKAP 450类似，CK 1d是高尔基体微管成核和维持高尔基体完整性所必需的。过表达的AKAP 450片段含有CK 1d结合位点抑制高尔基体衍生的微管成核，高尔基体分布的IFFT 20和纤毛发生。我们的研究结果表明，CK 1d介导的初级纤毛通过协调分布和推测功能的多个因素或附近的中心体和高尔基体，以促进纤毛运输。有缺陷的初级纤毛是负责几种疾病，包括神经管缺陷，多囊肾病和内脏逆位。异常的Wnt信号传导也可以引起这些异常。因此，我们对CK 1d和Dvl的研究可能为Wnt信号控制胚胎发育及其失调导致发病机制的方式提供新的见解。

We established that cells from Ewing tumors form neurites in response to Wnt-3a and have begun to define the mechanisms that account for this effect. Knockdown of the atypical PKCiota also blocked Wnt-3a-dependent neurite outgrowth. Wnt-3a stimulated the phosphorylation of PKCi. Dvl2 co-immunoprecipitated with PKCi, and this interaction did not occur when CK1 phosphorylation sites in Dvl2 were replaced with alanine residues. These results suggested that Dvl2 phosphorylation by CK1 was required for Dvl2-PKCi binding, which in turn might be necessary for neurite outgrowth. This work is significant not only because it provides insights about mechanisms involved in the formation of neurites. Many of the factors that participate in neurite outgrowth contribute to cell polarity in other contexts such as the formation of cellular extensions critical for cell migration. Inhibition of CK1d blocked primary ciliogenesis in hTERT-RPE and mIMCD3 cells. Mouse embryonic fibroblasts and retinal cells from CK1d null mice also exhibited ciliogenesis defects. Interference with CK1d expression or catalytic activity disrupted the pericentrosomal or ciliary distribution of several proteins involved in ciliary transport, including Rab11a, Rab8a, CEP290, PCM1 and polycystin-2, as well as the Golgi distribution of AKAP450. Similar to its binding partner AKAP450, CK1d was required for microtubule nucleation at the Golgi and maintenance of Golgi integrity. Overexpression of an AKAP450 fragment containing the CK1d binding site inhibited Golgi-derived microtubule nucleation, Golgi distribution of IFT20 and ciliogenesis. Our results suggest that CK1d mediates primary ciliogenesis by coordinating the distribution and presumably function of multiple factors at or near the centrosome and Golgi to promote ciliary transport. Defective primary cilia are responsible for several disorders including neural tube defects, polycystic kidney disease and situs inversus. Aberrant Wnt signaling also can elicit these abnormalities. Thus, our studies of CK1d and Dvl may provide new insight about the ways in which Wnt signaling controls embryonic development and its dysregulation contributes to pathogenesis.