QiuJiang Xi*, XiaoLiang Lou**,#, Li Han**, GuoSheng Wen**, ZhiGang Li***
*Department of Neurology, The Fourth Affiliated Hospital of Nanchang University, NanChang, PR China - **The Fourth Affiliated Hospital of Nanchang University, NanChang, PR China - ***Department of Neurology, Golden Hospital, First Affiliated Hospital of Gannan Medical College, GanNan, PR China
Objective: To explore the mechanism of lysosomal cathepsin L on apoptosis of rat cerebral ischemia-reperfusion cells through JNK signaling pathway.
Methods: The rats were then divided into the sham operation group, model group, JNK inhibitor SP600125 group (SP group), Cathepsin L inhibitor Z-FY-DMK group (CLI group). The model group, SP group and CLC group were divided into 2 h group, 6 h group, 12 h group and 24 h group according to the time point of cerebral ischemia and reperfusion. There were 12 rats in model group, SP group, CLC group 2 h subgroup, 6 h subgroup, 12 h subgroup, and 18 rats in CLC group 24 h subgroup. The area of cerebral infarction was calculated by picture analysis system. Apoptosis was detected by Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method. The protein expression of lysosomal cathepsin L and c-Jun amino terminal kinase (JNK) was detected by western blotting assay.
Results: There was no obvious infarction lesions in the sham operation group. The pale-white infarction lesions of different sizes could be found in the model group, SP group and CLI group. The area of relative infarction in the sham operation group was significantly smaller than that in other groups, and that in SP group and CLI group was remarkably smaller than that in model group (P<0.01). The expression of apoptosis in sham operation group was obviously lower than that in other groups (P<0.01). The expression of apoptosis was positively correlated with time in each group. The apoptosis expression in SP group and CLI group was significantly lower than that in model group (P<0.01). The expression of catapsin L, p-JNK protein in each time-point subgroup of model group was significantly higher than that in the sham-operated group (P<0.01). There was no significant difference in the expression of Cathepsin L between SP group and model group at each time point (P>0.05). The expression of pJNK was markedly lower in the subgroup of SP group than that in the model group (P<0.01). The expression of Cathepsin L and p-JNK protein in CLI group at each time point was significantly lower than that in model group (P<0.01). There was a positive correlation between Catapsin L and p-JNK by Spearman rank-related nonparametric test (r=0.765, P<0.01).
Conclusion: Cathepsin L may be located upstream of p-JNK signal molecules to regulate apoptosis. The specific inhibitor of Cathepsin L has inhibitory effect on Cathepsin L and p-JNK protein, and plays an important role in reducing the number of apoptosis and improving nerve function.
Lysosomal cathepsin L, JNK signaling pathway, cerebral ischemia-reperfusion, apoptosis.