Olfactory ensheathing cells (OECs) migrate from olfactory epithelium towards olfactory bulb (OB), contributing to formation of the presumptive olfactory nerve layer during development. However, it remains unclear that molecular mechanism of regulation of OEC migration in OB. In the present study, we found that OECs highly expressed the receptors of semaphorin 3A (Sema3A) in vitro and in vivo, whereas Sema3A displayed a gradient expression pattern with higher in inner layer of OB and lower in outer layer of OB. Furthermore, the collapse assays, Boyden chamber migration assays and single-cell migration assays showed that Sema3A induced the collapse of leading front of OECs and inhibited OEC migration. Thirdly, the leading front of OECs exhibited adaptation in a protein synthesis-independent manner, and endocytosis-dependent manner during Sema3A-induced OEC migration. Finally, Sema3A-induced collapse of leading front was required the decrease of focal adhesion and a retrograde F-actin flow in a cofilin activation-dependent manner. Taken together, these results demonstrate that Sema3A as an inhibitive migratory factor for OEC migration through cofilin activation is involved in the formation of olfactory nerve layer.

嗅鞘细胞（OEC）从嗅上皮向嗅球（OB）迁移，在发育过程中有助于推测性嗅神经层的形成。但是，尚不清楚OB中调节OEC迁移的分子机制。在本研究中，我们发现OEC在体外和体内均高表达semaphorin 3A（Sema3A）受体，而Sema3A显示的梯度表达模式在OB的内层较高而在OB的外层较低。此外，坍塌测定，博登室迁移测定和单细胞迁移测定表明，Sema3A诱导了OEC前沿的折叠，并抑制了OEC迁移。第三，在Sema3A诱导的OEC迁移过程中，OEC的前沿领域以蛋白质合成非依赖性和内吞作用依赖性方式表现出适应性。最后，要求Sema3A诱导的前导前壁塌陷以黏膜纤维蛋白激活依赖性方式减少粘着斑和逆行F-肌动蛋白流量。两者合计，这些结果表明Sema3A作为抑制OEC通过cofilin激活迁移的迁移因子参与嗅觉神经层的形成。