Glutathione depletion induces apoptosis of rat hepatocytes through activation of protein kinase C novel isoforms and dependent increase in AP-1 nuclear binding.
Treatment of isolated rat hepatocytes with the glutathione depleting agents L-buthionine-S,R-sulfoximine or diethylmaleate reproduced various cellular conditions of glutathione depletion, from moderate to severe, similar to those occurring in a wide spectrum of human liver diseases. To evaluate molecular changes and possible cellular dysfunction and damage consequent to a pathophysiologic level of GSH depletion, the effects of this condition on protein kinase C (PKC) isoforms were investigated, since these are involved in the intracellular specific regulatory processes and are potentially sensitive to redox changes. Moreover, a moderate perturbation of cellular redox state was found to activate novel PKC isoforms, and a clear relationship was shown between novel kinase activation and nuclear binding of the redox-sensitive transcription factor, activator protein-1 (AP-1). Apoptotic death of a significant number of cells, confirmed in terms of internucleosomal DNA fragmentation was a possible effect of these molecular reactions, and was triggered by a condition of glutathione depletion usually detected in human liver diseases. Finally, the inhibition of novel PKC enzymatic activity in cells co-treated with rottlerin, a selective novel kinase inhibitor, prevented glutathione-dependent novel PKC up-regulation, markedly moderated AP-1 activation, and protected cells against apoptotic death. Taken together, these findings indicate the existence of an apoptotic pathway dependent on glutathione depletion, which occurs through the up-regulation of novel PKCs and AP-1.
Domenicotti
C
C
Department of Experimental Medicine, General Pathology Section, University of Genova, Genova, Italy.
Paola
D
D
Vitali
A
A
Nitti
M
M
d'Abramo
C
C
Cottalasso
D
D
Maloberti
G
G
Biasi
F
F
Poli
G
G
Chiarpotto
E
E
Marinari
U M
UM
Pronzato
M A
MA
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D019328:Buthionine Sulfoximine / Q000494:pharmacology*; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D005978:Glutathione / Q000378:metabolism*; D022781:Hepatocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000166:cytology; D008297:Male; D008298:Maleates / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D018808:Transcription Factor AP-1 / Q000378:metabolism*
D007527:Isoenzymes; D008298:Maleates; D018808:Transcription Factor AP-1; D019328:Buthionine Sulfoximine; D000255:Adenosine Triphosphate; D011493:Protein Kinase C; C014476:diethyl maleate; D005978:Glutathione