Liver protection from apoptosis requires both blockage of initiator caspase activities and inhibition of ASK1/JNK pathway via glutathione S-transferase regulation.
Hepatoprotection mediated by free radical scavenging molecules such as dimethyl sulfoxide (Me(2)SO) arose the question as to whether this effect involved one or several anti-apoptotic signals. Here, using primary cultures of rat hepatocytes and in vivo thioacetamide-induced liver failure, we showed that Me(2)SO failed to prevent any cleavage of initiator caspase-8 and -9 but constantly inhibited procaspase-3 maturation and apoptosis execution, pointing to an efficient inhibition of cleaved initiator caspase activities. Evidence was recently provided that apoptosis might require both caspase and ASK1/JNK-p38 activities. We demonstrated that this kinase pathway was strongly inhibited in the presence of Me(2)SO whereas overexpression of ASK1 was able to restore caspase-3 activity and apoptosis. Interestingly, we also found that GST M1/2 and GST Alpha1/2 dropped under apoptotic conditions; furthermore transfection of GST M1, A1, or P1 to cells overexpressing ASK1, abolished caspase-3 activity and restored viability. This role of GSTs was further assessed by showing that their high expression level was tightly associated with inhibition of ASK1 activity in Me(2)SO-protected hepatocytes. Together, these results demonstrate that Me(2)SO-mediated hepatoprotection involves a dual inhibition of cleaved initiator caspase and ASK1/JNK-p38 activities. Furthermore, in highlighting the control of apoptosis by GSTs, these data provide new insights for analyzing the complex mechanisms of hepatoprotection.
Gilot
David
D
INSERM U522, Régulation des Equilibres fonctionnels du foie Normal et Pathologique, Avenue de la Bataille Flandre/Dunkerque, Hôpital Pontchaillou, 35033 Rennes, France. david.gilot@rennes.inserm.fr
Loyer
Pascal
P
Corlu
Anne
A
Glaise
Denise
D
Lagadic-Gossmann
Dominique
D
Atfi
Azeddine
A
Morel
Fabrice
F
Ichijo
Hidenori
H
Guguen-Guillouzo
Christiane
C
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D061945:Caspase Inhibitors; D016923:Cell Death; D002470:Cell Survival; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004587:Electrophoresis, Agar Gel; D004789:Enzyme Activation; D005609:Free Radicals; D015971:Gene Expression Regulation, Enzymologic; D005982:Glutathione Transferase / Q000378:metabolism*; D022781:Hepatocytes / Q000166:cytology; D015151:Immunoblotting; D007700:Kinetics; D008099:Liver / Q000473:pathology*; D048848:MAP Kinase Kinase Kinase 5; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008858:Microscopy, Phase-Contrast; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D010766:Phosphorylation; D011506:Proteins / Q000037:antagonists & inhibitors; D011817:Rabbits; D051381:Rats; D011917:Rats, Inbred Lew; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000378:metabolism; D053773:Transforming Growth Factor beta1; D051636:X-Linked Inhibitor of Apoptosis Protein; D048051:p38 Mitogen-Activated Protein Kinases
D061945:Caspase Inhibitors; D005609:Free Radicals; D011506:Proteins; C508961:Tgfb1 protein, mouse; C508962:Tgfb1 protein, rat; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D051636:X-Linked Inhibitor of Apoptosis Protein; D004247:DNA; D005982:Glutathione Transferase; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; D020930:MAP Kinase Kinase Kinases; C482859:Map3k5 protein, mouse; D009584:Nitrogen; D004121:Dimethyl Sulfoxide