Shibata Kazuki, Nakahara Soichiro, Shimizu Emi, Yamashita Toshihide, Matsuki Norio, Koyama Ryuta
Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
Neuroreport. 2013 Aug 7;24(11):609-15. doi: 10.1097/WNR.0b013e3283632c08.
Repulsive guidance molecule a (RGMa), which binds to its receptor neogenin, has been well determined as a repulsive axon guidance molecule. However, whether RGMa affects the growth of hippocampal mossy fibers, the axons of dentate granule cells, has been unknown. In the present study, we found that the primary neurons in the hippocampus express both RGMa and neogenin in the postnatal rats. To examine the role of RGMa in the mossy fiber growth, the morphology of granule cells was clearly visualized by transfecting membrane-targeted green fluorescent protein using a single-cell electroporation method in cultured hippocampal slices. In the slice cultures, we found that intrinsic RGMa is required to inhibit excess branching of the hippocampal mossy fibers. Furthermore, hyperexcitability-induced aberrant branching of the mossy fibers in the cultured slices was blocked by applying the recombinant RGMa protein. Therefore, this study suggests that RGMa regulates the proper axonal branching of hippocampal mossy fibers.
排斥导向分子a（RGMa）与其受体新生蛋白结合，已被明确确定为一种排斥性轴突导向分子。然而，RGMa是否影响海马苔藓纤维（齿状颗粒细胞的轴突）的生长尚不清楚。在本研究中，我们发现出生后大鼠海马中的原代神经元同时表达RGMa和新生蛋白。为了研究RGMa在苔藓纤维生长中的作用，在培养的海马切片中使用单细胞电穿孔法转染膜靶向绿色荧光蛋白，清晰地观察到了颗粒细胞的形态。在切片培养中，我们发现内源性RGMa是抑制海马苔藓纤维过度分支所必需的。此外，通过应用重组RGMa蛋白可阻断培养切片中苔藓纤维因过度兴奋诱导的异常分支。因此，本研究表明RGMa调节海马苔藓纤维轴突的正常分支。
