Miyamoto Yuki, Torii Tomohiro, Kawahara Kazuko, Tanoue Akito, Yamauchi Junji
Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535, Japan.
Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo 113-8510, Japan.
Biochem Biophys Rep. 2016 Mar 24;6:113-123. doi: 10.1016/j.bbrep.2016.03.013. eCollection 2016 Jul.
During embryonic development of the peripheral nervous system (PNS), Schwann cell precursors migrate along neuronal axons to their final destinations, where they will myelinate the axons after birth. While the intercellular signals controlling Schwann cell precursor migration are well studied, the intracellular signals controlling Schwann cell precursor migration remain elusive. Here, using a rat primary cell culture system, we show that Dock8, an atypical Dock180-related guanine-nucleotide exchange factor (GEF) for small GTPases of the Rho family, specifically interacts with Nck1, an adaptor protein composed only of Src homology (SH) domains, to promote Schwann cell precursor migration induced by platelet-derived growth factor (PDGF). Knockdown of Dock8 or Nck1 with its respective siRNA markedly decreases PDGF-induced cell migration, as well as Rho GTPase activation, in precursors. Dock8, through its unique N-terminal proline-rich motif, interacts with the SH3 domain of Nck1, but not with other adaptor proteins composed only of SH domains, e.g. Grb2 and CrkII, and not with the adaptor protein Elmo1. Reintroduction of the proline-rich motif mutant of Dock8 in Dock8 siRNA-transfected Schwann cell precursors fails to restore their migratory abilities, whereas that of wild-type Dock8 does restore these abilities. These results suggest that Nck1 interaction with Dock8 mediates PDGF-induced Schwann cell precursor migration, demonstrating not only that Nck1 and Dock8 are previously unanticipated intracellular signaling molecules involved in the regulation of Schwann cell precursor migration but also that Dock8 is among the genetically-conservative common interaction subset of Dock family proteins consisting only of SH domain adaptor proteins.
在周围神经系统（PNS）的胚胎发育过程中，雪旺细胞前体沿着神经元轴突迁移至其最终目的地，出生后它们将在此处使轴突髓鞘化。虽然控制雪旺细胞前体迁移的细胞间信号已得到充分研究，但控制雪旺细胞前体迁移的细胞内信号仍不清楚。在此，我们利用大鼠原代细胞培养系统表明，Dock8是一种与Rho家族小GTP酶相关的非典型Dock180鸟嘌呤核苷酸交换因子（GEF），它特异性地与仅由Src同源（SH）结构域组成的衔接蛋白Nck1相互作用，以促进血小板衍生生长因子（PDGF）诱导的雪旺细胞前体迁移。用各自的siRNA敲低Dock8或Nck1会显著降低PDGF诱导的前体细胞迁移以及Rho GTP酶激活。Dock8通过其独特的富含脯氨酸的N端基序与Nck1的SH3结构域相互作用，但不与其他仅由SH结构域组成的衔接蛋白相互作用，例如Grb2和CrkII，也不与衔接蛋白Elmo1相互作用。在转染了Dock8 siRNA的雪旺细胞前体中重新引入Dock8的富含脯氨酸基序突变体无法恢复其迁移能力，而野生型Dock8则可以恢复这些能力。这些结果表明，Nck1与Dock8的相互作用介导了PDGF诱导的雪旺细胞前体迁移，这不仅表明Nck1和Dock8是先前未预料到的参与调节雪旺细胞前体迁移的细胞内信号分子，而且表明Dock8属于仅由SH结构域衔接蛋白组成的Dock家族蛋白的遗传保守共同相互作用子集。
