A non-toxic heat shock protein 70 inducer, geranylgeranylacetone, suppresses apoptosis of cultured rat hepatocytes caused by hydrogen peroxide and ethanol.
OBJECTIVE
A stress-inducible heat shock protein 70 (HSP70) is one of the best-known endogenous factors protecting cell injury under various pathological conditions. The aim of this study was to examine anti-apoptotic actions of a non-toxic HSP70 inducer, geranylgeranylacetone (GGA), on hepatocytes exposed to hydrogen peroxide (H2O2) or ethanol.


METHODS
Primary cultures of rat hepatocytes were treated with different concentrations of GGA and exposed to 0.5 mM H202 or 100 mM ethanol. The heat shock response was assessed by measuring the activation of heat shock factor 1 (HSF1), HSP70 mRNA expression, and accumulations of HSP70, HSP90, and HSP27. Apoptosis was evaluated by DNA fragmentation.


RESULTS
Pretreatment with 1 microM GGA for 2 h enhanced nuclear translocation and phosphorylation of HSF1, HSF1-DNA binding, HSP70 mRNA expression, and its accumulation, when the cells were exposed to H202 or ethanol. In association with this accelerated response, GGA suppressed the insult-induced activation of c-Jun N-terminal kinases, caspase 9, and caspase 3-like proteases, leading to significant inhibition of apoptosis.


CONCLUSIONS
GGA exerted anti-apoptotic actions, at least in part, by priming hepatocytes for enhanced HSP70 induction. Our results suggest that GGA may have a potential benefit for the treatment of alcoholic and ischemia-reperfusion liver injuries.
Ikeyama
S
S
First Department of Surgery, School of Medicine, The University of Tokushima, Japan.
Kusumoto
K
K
Miyake
H
H
Rokutan
K
K
Tashiro
S
S
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000502:physiology; D004224:Diterpenes / Q000494:pharmacology*; D000431:Ethanol / Q000494:pharmacology*; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis*; D000076249:Heat Shock Transcription Factors; D022781:Hepatocytes / Q000187:drug effects / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008297:Male; D048055:Mitogen-Activated Protein Kinase 8; D048056:Mitogen-Activated Protein Kinase 9; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution; D014157:Transcription Factors
D004268:DNA-Binding Proteins; D004224:Diterpenes; D018840:HSP70 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; C000619709:Hsf1 protein, rat; D016877:Oxidants; D014157:Transcription Factors; D000431:Ethanol; D006861:Hydrogen Peroxide; D048056:Mitogen-Activated Protein Kinase 9; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; C031049:geranylgeranylacetone