Department of Life Science and Medical Bio-Science, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan.
Department of Life Science and Medical Bio-Science, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan; Japan Society for the Promotion of Science, Japan.
Brain Res. 2020 Jun 1;1736:146762. doi: 10.1016/j.brainres.2020.146762. Epub 2020 Mar 7.
Proper migration and positioning of Purkinje cells are important for formation of the developing cerebellum. Although several cyclin-dependent kinase 5 (Cdk5) substrates are known to be critical for ordered neuronal migration, there are no reports of mutant mouse-based, in vivo studies on the function of Cdk5-phosphorylation substrates in migration of Purkinje cells. We focused on the analysis of collapsin response mediator protein 2 (CRMP2), one of the Cdk5 substrates, because a previous study reported migration defects of cortical neurons with shRNA-mediated knockdown of CRMP2. However, CRMP2 KI/KI mice, in which Cdk5-phosphorylation is inhibited, showed little defects in Purkinje cell migration and positioning. We hypothesized compensatory redundant functions of the other CRMPs, and analyzed the migration and positioning of Purkinje cells in the cerebellum in every combination of CRMP1 knockout (KO), CRMP2 KI/KI, and CRMP4 KO mice. Severe disturbance of migration and positioning of Purkinje cells were observed in the triple mutant mice. We also found motor coordination defects in the triple CRMPs mutant mice. These results suggest the importance of both, phosphorylation of CRMP2 by Cdk5 and the redundant functions of CRMP1 and CRMP4 in proper migration and positioning of Purkinje cells in developing cerebellum.
浦肯野细胞的正确迁移和定位对于发育中的小脑的形成很重要。虽然已知几种细胞周期蛋白依赖性激酶 5（Cdk5）底物对于有序的神经元迁移至关重要，但尚未有基于突变小鼠的体内研究报告 Cdk5 磷酸化底物在浦肯野细胞迁移中的功能。我们专注于分析细胞周期蛋白依赖性激酶 5 底物之一 collapsin 反应介质蛋白 2（CRMP2），因为之前的一项研究报告说，使用 shRNA 介导的 CRMP2 敲低会导致皮质神经元迁移缺陷。然而，CRMP2 KI/KI 小鼠，其 Cdk5 磷酸化被抑制，在浦肯野细胞迁移和定位方面几乎没有缺陷。我们假设其他 CRMPs 存在补偿性冗余功能，并分析了 CRMP1 敲除（KO）、CRMP2 KI/KI 和 CRMP4 KO 小鼠中每一种组合的小脑浦肯野细胞的迁移和定位。在三重突变小鼠中观察到浦肯野细胞迁移和定位的严重干扰。我们还发现三重 CRMPs 突变小鼠存在运动协调缺陷。这些结果表明，Cdk5 对 CRMP2 的磷酸化以及 CRMP1 和 CRMP4 的冗余功能对于发育中小脑浦肯野细胞的正确迁移和定位都很重要。
