Atypical Protein Kinase C Phosphorylates Par6 and Facilitates Transforming Growth Factor β-Induced Epithelial-to-Mesenchymal Transition
Atypical Protein Kinase C Phosphorylates Par6 and Facilitates Transforming Growth Factor β-Induced Epithelial-to-Mesenchymal Transition
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DOI：
10.1128/mcb.00837-12
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发表时间：
2013-03-01
影响因子：
5.3
通讯作者：
Di Guglielmo, Gianni M.
中科院分区：
文献类型：
--
作者：
Gunaratne, Adrian;Thai, Boun L.;Di Guglielmo, Gianni M.
上皮-间充质转化（EMT）是由细胞信号传导途径控制的，其触发细胞-细胞粘附的丧失并导致细胞骨架的重构。转化生长因子β（TGF-β）已显示通过II型TGF-β受体对保守丝氨酸残基（S345）上的Par 6的磷酸化来调节细胞可塑性。我们发现非典型蛋白激酶C（aPKC）是非小细胞肺癌（NSCLC）细胞中这一信号通路的重要组成部分。我们发现aPKC，PKC iota，通过Par 6与TGF-β受体相互作用，这些蛋白定位于迁移细胞的前缘。此外，在aPKC存在下，TGF-β受体对丝氨酸345上的Par 6磷酸化增强。发现aPKC激酶活性以及与Par 6的关联对于Par 6磷酸化是重要的。实际上，靶向aPKC的小干扰RNA减少了TGF-β诱导的RhoA和E-cadherin损失、细胞形态学变化、应力纤维产生和NSCLC细胞的迁移。有趣的是，将磷酸化模拟物Par 6（Par 6-S345 E）重新引入aPKC沉默的细胞中，在TGF-β刺激下挽救了RhoA和E-钙粘蛋白的损失。总之，我们的研究结果表明，aPKC与TGF-β受体合作，调节磷酸化Par 6依赖的EMT和细胞迁移。
Epithelial-to-mesenchymal transition (EMT) is controlled by cellular signaling pathways that trigger the loss of cell-cell adhesion and lead to the restructuring of the cell cytoskeleton. Transforming growth factor beta (TGF-beta) has been shown to regulate cell plasticity through the phosphorylation of Par6 on a conserved serine residue (S345) by the type II TGF-beta receptor. We show here that atypical protein kinase C (aPKC) is an essential component to this signaling pathway in non-small-cell lung cancer (NSCLC) cells. We show that the aPKC, PKC iota, interacts with TGF-beta receptors through Par6 and that these proteins localize to the leading edge of migrating cells. Furthermore, Par6 phosphorylation on serine 345 by TGF-beta receptors is enhanced in the presence of aPKC. aPKC kinase activity, as well as an association with Par6, were found to be important for Par6 phosphorylation. In effect, small interfering RNA-targeting aPKC reduces TGF-beta-induced RhoA and E-cadherin loss, cell morphology changes, stress fiber production, and the migration of NSCLC cells. Interestingly, reintroduction of a phosphomimetic Par6 (Par6-S345E) into aPKC-silenced cells rescues both RhoA and E-cadherin loss with TGF-beta stimulation. In conclusion, our results suggest that aPKCs cooperate with TGF-beta receptors to regulate phospho-Par6-dependent EMT and cell migration.