Joly Sandrine, Pernet Vincent
CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, Université Laval, Quebec City, Quebec, Canada.
J Neurochem. 2016 Aug;138(4):571-86. doi: 10.1111/jnc.13701. Epub 2016 Jul 6.
In this study, we used a classical optic nerve injury model to address the function of the sphingosine 1-phosphate (S1P)-S1P receptor (S1PR) axis in retinal ganglion cell (RGC) death and axonal growth. After lesion, the expression of S1PR1 was generally reduced in axotomized RGCs but persisted in αRGCs, a subpopulation of injury-resistant RGCs. Silencing S1PR1 with an adeno-associated virus serotype 2 (AAV2) containing a shRNA specific to S1PR1 (AAV2.shRNA-S1PR1) exacerbated the loss of RGCs induced by optic nerve crush; the rate of RGC survival was decreased by more than 24% in retinae infected with AAV2.shRNA-S1PR1 compared with AAV2.shRNA-scrambled or AAV2.GFP control treatments. In the superior and temporal regions of the retina, cell death rose by more than ~ 35% and ~ 50%, respectively, in comparison with control groups. In the optic nerve, S1PR1 silencing markedly reduced axonal sprouting after the lesion relative to control animals. Early after optic nerve crush, 67% of αRGCs stained for osteopontin were lost in retinae infected with AAV2.shRNA-S1PR1, whereas the number of intrinsically photosensitive RGCs expressing melanopsin, another injury-resistant RGC type, was not affected. Moreover, retinal infection with AAV2.shRNA-S1PR1 down-regulated mammalian target of rapamycin pathway activation in αRGCs. Together, our results reveal that S1PR1 contributes to survival and growth mechanisms in injured RGCs by regulating the mammalian target of rapamycin pathway. The role of sphingosine 1-phosphate receptor 1 (S1PR1) was studied in retinal ganglion cell survival and axonal growth after optic nerve injury. After axonal damage, S1PR1 expression was decreased in retinal neurons. Viral-mediated S1PR1 down-regulation enhanced injury-induced cell death and reduced spontaneous axonal growth. In injury-resistant retinal neurons, the activation of mTOR signalling was down-regulated by silencing S1PR1, suggesting an important role for S1PR1 in neuronal growth and survival mechanisms in vivo.
在本研究中，我们使用经典的视神经损伤模型来探讨1-磷酸鞘氨醇（S1P）-S1P受体（S1PR）轴在视网膜神经节细胞（RGC）死亡和轴突生长中的作用。损伤后，S1PR1的表达在轴突切断的RGC中普遍降低，但在αRGC（一种抗损伤的RGC亚群）中持续存在。用携带针对S1PR1的短发夹RNA（shRNA）的2型腺相关病毒（AAV2）沉默S1PR1（AAV2.shRNA-S1PR1）会加剧视神经挤压诱导的RGC损失；与AAV2.shRNA-乱序或AAV2.GFP对照处理相比，感染AAV2.shRNA-S1PR1的视网膜中RGC存活率降低了超过24%。在视网膜的上方和颞侧区域，与对照组相比，细胞死亡分别增加了超过约35%和约50%。在视神经中，与对照动物相比，S1PR1沉默显著减少了损伤后的轴突发芽。视神经挤压后早期，感染AAV2.shRNA-S1PR1的视网膜中67%的骨桥蛋白染色的αRGC丢失，而表达黑视蛋白的内在光敏RGC（另一种抗损伤的RGC类型）的数量未受影响。此外，用AAV2.shRNA-S1PR1感染视网膜会下调αRGC中雷帕霉素靶蛋白通路的激活。总之，我们的结果表明，S1PR1通过调节雷帕霉素靶蛋白通路，有助于受损RGC的存活和生长机制。研究了1-磷酸鞘氨醇受体1（S1PR1）在视神经损伤后视网膜神经节细胞存活和轴突生长中的作用。轴突损伤后，视网膜神经元中S1PR1表达降低。病毒介导的S1PR1下调增强了损伤诱导的细胞死亡并减少了自发轴突发芽。在抗损伤的视网膜神经元中，沉默S1PR1会下调mTOR信号的激活，表明S1PR1在体内神经元生长和存活机制中起重要作用。
