Hida Tomonobu, Nakamura Fumio, Usui Hiroshi, Takeuchi Kan, Yamashita Naoya, Goshima Yoshio
Departments of Molecular Pharmacology, Yokohama City University Graduate School of Medicine, Yokohama 236-0004, Japan.
Departments of Molecular Pharmacology, Yokohama City University Graduate School of Medicine, Yokohama 236-0004, Japan.
Brain Res. 2015 Feb 19;1598:46-56. doi: 10.1016/j.brainres.2014.12.028. Epub 2014 Dec 18.
The establishment of neuronal polarity is necessary for proper neuronal wiring. Semaphorin3A (Sema3A), originally identified as a repulsive axon guidance molecule, exerts a wide variety of biological functions through signaling pathways including sequential phosphorylation of collapsin response mediator protein by cyclin-dependent kinase-5 (Cdk5) and glycogen synthase kinase-3β (GSK3β). Sema3A acts on its receptor neuropilin-1 to regulate axonal transport. To delineate mechanism by which Sema3A induces axonal transport, we investigate whether GSK3β is involved in mediating Sema3A-induced axonal transport. 4-Benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione, an inhibitor of GSK3β, suppressed Sema3A-induced antero- and retrograde axonal transport. Introduction of either GSK3β mutants, GSK3β-L128A or K85M, suppressed Sema3A-induced axonal transport. On the other hand, introduction of GSK3β-R96A did not affect the Sema3A effect, suggesting that unprimed substrates are primarily involved in Sema3A-induced axonal transport. Overexpression of a partial fragment of frequently rearranged in advanced T-cell lymphomas 1 (FRATtide), which interferes the interaction between GSK3β and Axis inhibitor-1 (Axin-1), also suppressed Sema3A-induced transport. siRNA knockdown of Axin-1, an unprimed substrate of GSK3β, suppressed Sema3A-induced antero- and retrograde axonal transport. These results indicate that GSK3β and Axin-1 are involved in Sema3A-induced bidirectional axonal transport. This finding should provide a clue for understanding of mechanisms of a wide variety of biological activities of Sema3A.
神经元极性的建立对于正确的神经元连接至关重要。信号素3A（Sema3A）最初被鉴定为一种轴突排斥导向分子，它通过包括细胞周期蛋白依赖性激酶5（Cdk5）和糖原合酶激酶3β（GSK3β）对塌陷反应介导蛋白进行顺序磷酸化的信号通路发挥多种生物学功能。Sema3A作用于其受体神经纤毛蛋白-1以调节轴突运输。为了阐明Sema3A诱导轴突运输的机制，我们研究了GSK3β是否参与介导Sema3A诱导的轴突运输。4-苄基-2-甲基-1,2,4-噻二唑烷-3,5-二酮，一种GSK3β抑制剂，抑制了Sema3A诱导的顺行和逆行轴突运输。引入GSK3β突变体GSK3β-L128A或K85M可抑制Sema3A诱导的轴突运输。另一方面，引入GSK3β-R96A并不影响Sema3A的作用，这表明未磷酸化的底物主要参与Sema3A诱导的轴突运输。过表达在晚期T细胞淋巴瘤1中频繁重排的部分片段（FRATtide），其干扰GSK3β与轴抑制蛋白-1（Axin-1）之间的相互作用，也抑制了Sema3A诱导的运输。GSK3β的未磷酸化底物Axin-1的小干扰RNA敲低抑制了Sema3A诱导的顺行和逆行轴突运输。这些结果表明GSK3β和Axin-1参与Sema3A诱导的双向轴突运输。这一发现应为理解Sema3A多种生物学活性的机制提供线索。
