The essential role of PKCalpha in the protective effect of heat-shock pretreatment on TNFalpha-induced apoptosis in hepatic epithelial cell line.
During sepsis, hepatic apoptosis occurred, which is associated with inactivation of PKCalpha and elevation of tumor necrosis factor-alpha (TNFalpha), an apoptosis trigger. Heat shock, accompanied by the increase of heat-shock protein (Hsp72), has been shown to exhibit a protective role on cell survival. However, Hsp72 was unable to express during sepsis when the apoptosis was markedly increased. We hypothesized that hepatic apoptosis during sepsis may be due to the failure to induce expression of Hsp72, which is activated by PKC-phosphorylated HSF. This study was designed to examine the role of PKCalpha in Hsp72 expression and the anti-apoptotic effect of Hsp72 on hepatic epithelial cells by analyzing a TNFalpha-induced apoptosis system. The following results were observed: (1) Hsp72 was highly expressed at 8 h after heat-shock treatment in a clone 9 hepatic epithelial cell line; (2) the protein expression of PKCalpha in membrane-associated fraction was decreased by TNFalpha treatment; (3) the TNFalpha-induced cell death, especially apoptosis, was diminished by heat-shock pretreatment; (4) in the presence of PKCalpha antisense, which blocks the PKCalpha resynthesis, no protective effect of heat-shock pretreatment was observed, and the protein expression of Hsp72 was significantly suppressed. These results suggest that PKCalpha plays a critical role in the expression of Hsp72, which subsequently protects against TNFalpha-induced hepatic apoptosis.
Yang
Rei-Cheng
RC
Department of Pediatrics, Chung Ho Memorial Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
Jao
Hsiao-Ching
HC
Huang
Li-Ju
LJ
Wang
Shu-Jung
SJ
Hsu
Chin
C
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology* / Q000201:enzymology; D050884:HSP72 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000096:biosynthesis* / Q000502:physiology; D006358:Hot Temperature / Q000627:therapeutic use; D008099:Liver / Q000166:cytology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000096:biosynthesis / Q000187:drug effects / Q000502:physiology*; D051571:Protein Kinase C-alpha; D051381:Rats; D018805:Sepsis / Q000473:pathology; D013312:Stress, Physiological; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D004268:DNA-Binding Proteins; D050884:HSP72 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha