Role of glycogen synthase kinase-3 in TNF-alpha-induced NF-kappaB activation and apoptosis in hepatocytes.
Nuclear factor-kappaB (NF-kappaB) prevents hepatocytes from undergoing apoptosis during development and liver regeneration. Mice with inactivated glycogen synthase kinase (GSK)-3beta die from hepatocyte apoptosis during development due to a defect in NF-kappaB activation (Hoeflich KP, Luo J, Rubie EA, Tsao MS, Jin O, and Woodgett JR. Nature 406: 86-90, 2000). In this study, we determined the role of GSK-3 in TNF-alpha-induced NF-kappaB activation and cell death in primary hepatocytes. LiCl, an established inhibitor of GSK-3, sensitized primary rat hepatocytes toward TNF-alpha-mediated apoptosis resulting in 90% cell death after 24 h. This was accompanied by increased caspase 8-like and 3-like activities, nuclear fragmentation and DNA laddering. LiCl treatment had no effect on IkappaB-alpha degradation, IkappaB kinase (IKK) activity, NF-kappaB binding activity, and p65 nuclear import and export, but decreased transcription of the NF-kappaB-dependent inducible nitric oxide synthase gene and a NF-kappaB-driven reporter gene. The p65 sequence revealed four potential GSK-3 phosphorylation sites within its COOH-terminal transactivation domains and recombinant GSK-3beta phosphorylated glutathione S-transferase (GST)-p65(354-551), but not GST-p65(1-305) in vitro. These results indicate that GSK-3 protects hepatocytes from TNF-alpha-induced apoptosis through p65 phosphorylation and upregulation of NF-kappaB transactivation.
Schwabe
Robert F
RF
Department of Medicine, Biochemistry, and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
Brenner
David A
DA
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D002478:Cells, Cultured; D038362:Glycogen Synthase Kinase 3; D038341:Glycogen Synthase Kinases; D022781:Hepatocytes / Q000187:drug effects* / Q000502:physiology*; D020672:I-kappa B Proteins / Q000378:metabolism; D018021:Lithium Chloride / Q000494:pharmacology; D008297:Male; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D051996:Transcription Factor RelA; D014158:Transcription, Genetic / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D020672:I-kappa B Proteins; D016328:NF-kappa B; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D038341:Glycogen Synthase Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D038362:Glycogen Synthase Kinase 3; D018021:Lithium Chloride