Centre for Ophthalmology, University Eye Hospital, Tübingen, Germany.
Graefes Arch Clin Exp Ophthalmol. 2012 Jan;250(1):39-50. doi: 10.1007/s00417-011-1791-9. Epub 2011 Sep 2.
The death and the failure of neurons to regenerate their axons after lesion of the central nervous system in mammals, as in the case of spinal cord injury and optic nerve trauma, remain a challenge. In this study, we focused on the repulsive guidance molecule A (RGMA) and its receptor neogenin. Since it was reported that RGMA+ cells accumulate in lesioned areas after spinal cord injury, brain trauma, and optic nerve crush, and curiously, anti-apoptotic effects of RGMA were also described, we investigated the role of RGMA and neogenin in the retina after optic nerve crush (ONC).
We evaluated the spatial and temporal protein pattern of RGMA and neogenin in the rat retina without (non-regenerating model) or with (regenerating model) lens injury (LI). We investigated the presence of RGMA, neogenin and other proteins at up to nine time points (6 h-20 days post-surgery) by performing immunohistochemistry and Western blots.
Independent of the treatment, RGMA protein was present in the nuclear layers (NLs), plexiform layers (PLs), nerve fiber layer (NFL), and in retinal ganglion cells (RGCs) of the rat retina. RGC and nerve fibers were always RGMA+. Further RGMA+ cells in the retina were blood vessel endothelial cells, astrocytes, Müller cells, and some microglial cells. The RGMA pattern for the specific retinal cells resembled those of previously published data. The neogenin pattern was congruent to the RGMA pattern. Western blots of retinal tissue showed further RGMA+ products only in LI animals. Furthermore, a higher amount of RGMA was found in the retinae of ONC + LI rats compared to ONC rats.
Although a difference in the localization of RGMA is not obvious, the difference in the amount of RGMA is striking, the higher amount of RGMA in the retinae of ONC + LI rats compared to ONC rats indicates a role for RGMA during degeneration/regeneration processes. Our results are consistent with several reported neuroprotective effects of RGMA. Our new data showing the upregulation of RGMA after ONC in our regenerating model (plus LI) confirm these findings conducted in different settings.
哺乳动物中枢神经系统（如脊髓损伤和视神经创伤）损伤后，神经元死亡且轴突无法再生，这仍是一个挑战。在这项研究中，我们专注于排斥性导向分子 A（RGMA）及其受体 neogenin。由于有报道称，RGMA+细胞在脊髓损伤、脑外伤和视神经挤压后会在损伤部位积累，而且令人好奇的是，RGMA 还具有抗细胞凋亡作用，因此我们研究了 RGMA 和 neogenin 在视神经挤压（ONC）后视网膜中的作用。
我们评估了未受伤（非再生模型）或受伤（再生模型）晶状体的大鼠视网膜中 RGMA 和 neogenin 的时空蛋白模式。我们通过免疫组织化学和 Western blot 分析，在 6 小时至 20 天手术后的 9 个时间点（6 小时-20 天手术后）检测 RGMA、neogenin 和其他蛋白质的存在。
无论是否接受治疗，RGMA 蛋白均存在于大鼠视网膜的核层（NLs）、神经纤维层（NFL）和神经节细胞层（RGCs）中。RGC 和神经纤维始终为 RGMA+。视网膜中的其他 RGMA+细胞为血管内皮细胞、星形胶质细胞、Müller 细胞和一些小胶质细胞。特定视网膜细胞的 RGMA 模式与先前发表的数据相似。neogenin 模式与 RGMA 模式一致。视网膜组织的 Western blot 仅显示 LI 动物的 RGMA+产物。此外，ONC + LI 大鼠的视网膜中 RGMA 含量高于 ONC 大鼠。
尽管 RGMA 的定位差异不明显，但 RGMA 的含量差异显著，ONC + LI 大鼠的视网膜中 RGMA 含量较高表明 RGMA 在变性/再生过程中起作用。我们的结果与 RGMA 的几种报道的神经保护作用一致。我们在再生模型（加 LI）中发现 ONC 后 RGMA 上调的新数据证实了在不同环境中进行的这些发现。
