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PC2/CPE mediated neuropeptide processing and in vitro stressing response of RGC-5 cell

Song-Shan Tang, Juan-Hui Zhang, Huan-Xin Liu, Rong Qi

PC2 and CPE are two major members of the pro-protein processing convertases which involve in the maturation of neuropeptide. The RGC-5 cell differentiated in 0.1M staurosporine for 24h was stressed by differentOGDinjuries. The acute or chronic OGD-inducing cell death rateswere obtained by using PI or TUNELstaining. By using theWestern blotmethod and artificial PC2 substrate, the PC2, CPE and preproNPYprotein levels in the ischemic RGC-5 cells and conditioned medium were analyzed. The results showed that the ischemia caused substantial cell death in an OGD dose-dependent manner. In the cells, proPC2 and preproNPYprotein levels gradually increased whereas proCPE gradually decreased. After the OGDs, the PC2 activitieswere decreased. In themedium, proPC2 and PC2 proteins gradually decreased whereas proCPE, CPE, and preproNPY proteins gradually increased. The experimental results demonstrated thatOGD inhibits the neuropeptide pro-protein processing system by reducing PC2 activity and the maturation of proPC2. The aggregation of the pro-proteins and the increase of the active CPE excision adversely exacerbate the cell injury. These results demonstrate that PCs mediated processing systemplays a critical role in the ischemic stress of RGC-5 cells.