Expression And Role Of C-Jun N-terminal Kinase In Hypoxic Renal Tubular Epithelial Cell Injury

Objective Through detecting activated c-Jun N-terminal kinase(pJNK),c-Jun N-terminal kinase-1(JNK1)and c-Jun N-terminal kinase-2(JNK2)in hypoxic renal tubular epithelial(RTEC)injury,to investigate the expression and role of JNKs in hypoxic RTEC injury.Methods RTECs were cultured in vitro and randomly divided into control group,hypoxia 24 h group(H24),hypoxia 48 h group(H48)and hypoxia 72 h group(H72).Cells in control group were cultured under normal conditions instead of being treated.The hypoxia-induced RTEC models were established in hypoxia 24 h,hypoxia 48 h and hypoxia 72 h groups.Cell samples were collected at 24 h,48 h and 72 h after hypoxia.The morphological changes of the cells could be observed under light microscope.Using RT-RCR to detect c-Jun N-terminal kinase 1(JNK1),c-Jun N-terminal kinase 2(JNK2)and α-smooth muscle actin MRNA expression.Western blot was used to detect the expression of JNK1,JNK2,pJNK,α-SMA and p-caspase3 in each group of cells;flow cytometry could detect apoptosis rate in each group.Results Under light microscope,compared with the control group,the RTEC morphology in the hypoxia 24 h group was basically the same as that in the control group;in the hypoxic 48 h group,the cells shrank,the cell gap widened,and sharpening occurred on both ends of the cells;the cells in the 72 h hypoxia group were disordered,sparse,the cells collapsed,and the sharpening occurred on both ends of the cells being acute obviously.Compared with the control group,the expression of α-SMA protein and mRNA,the expression of JNK1 protein and mRNA,the expression of pJNK and p-caspase3 protein in RTEC of hypoxia group were significantly increased(all P<0.05).The longer the hypoxia duration,the more significant the increase;compared with the control group,the expression of JNK2 protein and mRNA of RTEC in hypoxia group were significantly decreased(all P <0.05).The longer time the lack of oxygen,the more significant the decrease;The apoptosis rate of hypoxia group was significantly higher than that of control group(P <0.05).The longer time the hypoxia,the higher the rate of apoptosis.The protein expression of pJNK and JNK1 were positively correlated with the expression of α-SMA or p-caspase3 protein(both P<0.01),while the expression of JNK2 protein was negatively correlated with the expression of α-SMA or pcaspase3 protein(P<0.01).Conclusion In rat hypoxic-RETC injury,both the increased expression of pJNK and JNK1 and decreased expression of JNK2 were involved in the development of RTEC injury.Hypoxic-RTEC injury is likely to be positively regulated by JNK1 and likely to be negatively regulated by JNK2.