Phosphorylation of c-Jun N-terminal kinase in human hepatoblastoma cells is transiently increased by cold exposure and further enhanced by subsequent warm incubation of the cells.
During a cold preservation and reperfusion process of organs, cells are exposed to two major stresses, i.e. changes in oxygen concentration and temperature. c-Jun N-terminal kinase (JNK) /stress-activated protein kinase is activated by various stresses through its phosphorylation. Although hypoxia and subsequent reoxygenation is known to activate JNK, little is known about effects of hypothermia and subsequent rewarming on JNK activation. Thus, we investigated the activation of JNK in human hepatoblastoma (HepG2) cells exposed to a temperature of 5 degrees C and in those rewarmed at 37 degrees C. Western blot analysis using an anti-phospho-JNK antibody revealed that p54 JNK was transiently phosphorylated in cold-stressed cells. In addition, the phosphorylation of p54 JNK was further increased by rewarming of the cells. Since translational and transcriptional abilities were markedly reduced in the cold-stressed cells, effects of translation and transcription inhibitors on the phosphorylation of p54 JNK were determined. Cycloheximide, but not actinomycin D, increased the phosphorylation of p54 JNK in HepG2 cells. These results suggest that hypothermia alone transiently increases the p54 JNK phosphorylation possibly through reduction of protein synthesis and that rewarming after hypothermia stimulates the phosphorylation of p54 JNK.
Ohsaka
Yasuhito
Y
Research Institute of Biological Resources, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-higashi, Toyohira-ku, Sapporo 065-8517, Japan.
Ohgiya
Satoru
S
Hoshino
Tamotsu
T
Ishizaki
Kozo
K
D017209:Apoptosis; D003080:Cold Temperature; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D018197:Hepatoblastoma / Q000201:enzymology*; D006801:Humans; D007036:Hypothermia, Induced; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D014176:Protein Biosynthesis / Q000187:drug effects; D017694:Rewarming; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
D003609:Dactinomycin; D003513:Cycloheximide; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases