Role of JNK phosphorylation in intestinal ischemia/reperfusion injury in mice

Abstract

Objective To explore the role of c-Jun NH2 terminal kinase(JNK) activation and JNK-mediated apoptotic signal pathway in intestinal ischemia/reperfusion(II/R) in mice.Methods C57BL/6 mice were randomly divided into sham-operated group(n=6) and II/R groups(n=36);the latter was further divided according to time after perfusion(0,0.5,1,4,6 and 12 h).Animal II/R model was established by clamping the superior mesenteric artery(SMA) for 40 min followed by reperfusion.Animals in the sham-operated group received no clamping.Animals in the two groups were sacrificed at defined time points,and the expression of JNK,phosphorylation(phospho-) JNK,cleaved caspase-3,Bcl-2 and Bax protein in the intestinal tissue was examined by Western blotting analysis,and the pathological changes of ileum tissue were observed under optical microscope.Results Most severe intestinal injury was found at the early stage of reperfusion,and the intestinal tissues almost recovered 12 h later.The phospho-JNK in the intestine was significantly elevated within 1 h after II/R compared with sham group(P0.01).Cleaved caspase-3 was significantly increased in II/R group at 0.5 h,1 h after reperfusion compared to sham group(P0.01);the expression of Bcl-2 protein in II/R group was significantly decreased compared with the sham-operated group(P0.01),and there was no significant difference in Bax expression between different groups.Conclusion JNK phosphorylation plays an essential role in the intestinal damages induced by II/R,possibly through down-regulating Bcl-2 protein expression and caspase-3 dependent apoptosis pathway.