Tumor necrosis factor-alpha upregulates 11beta-hydroxysteroid dehydrogenase type 1 expression by CCAAT/enhancer binding protein-beta in HepG2 cells.
The enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) catalyzes the conversion of inactive to active glucocorticoids. 11beta-HSD1 plays a crucial role in the pathogenesis of obesity and controls glucocorticoid actions in inflammation. Several studies have demonstrated that TNF-alpha increases 11beta-HSD1 mRNA and activity in various cell models. Here, we demonstrate that mRNA and activity of 11beta-HSD1 is increased in liver tissue from transgenic mice overexpressing TNF-alpha, indicating that this effect also occurs in vivo. To dissect the molecular mechanism of this increase, we investigated basal and TNF-alpha-induced transcription of the 11beta-HSD1 gene (HSD11B1) in HepG2 cells. We found that TNF-alpha acts via p38 MAPK pathway. Transient transfections with variable lengths of human HSD11B1 promoter revealed highest activity with or without TNF-alpha in the proximal promoter region (-180 to +74). Cotransfection with human CCAAT/enhancer binding protein-alpha (C/EBPalpha) and C/EBPbeta-LAP expression vectors activated the HSD11B1 promoter with the strongest effect within the same region. Gel shift and RNA interference assays revealed the involvement of mainly C/EBPalpha, but also C/EBPbeta, in basal and only of C/EBPbeta in the TNF-alpha-induced HSD11B1 expression. Chromatin immunoprecipitation assay confirmed in vivo the increased abundance of C/EBPbeta on the proximal HSD11B1 promoter upon TNF-alpha treatment. In conclusion, C/EBPalpha and C/EBPbeta control basal transcription, and TNF-alpha upregulates 11beta-HSD1, most likely by p38 MAPK-mediated increased binding of C/EBPbeta to the human HSD11B1 promoter. To our knowledge, this is the first study showing involvement of p38 MAPK in the TNF-alpha-mediated 11beta-HSD1 regulation, and that TNF-alpha stimulates enzyme activity in vivo.
Ignatova
Irena D
ID
Depts. of Nephrology and Hypertension and Clinical Research, Freiburgstrasse 15, Univ. Hospital, Berne, CH-3010 Berne, Switzerland.
Kostadinova
Radina M
RM
Goldring
Christopher E
CE
Nawrocki
Andrea R
AR
Frey
Felix J
FJ
Frey
Brigitte M
BM
D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1 / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006528:Carcinoma, Hepatocellular / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D008113:Liver Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D012333:RNA, Messenger / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D015854:Up-Regulation / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology
D022782:CCAAT-Enhancer-Binding Protein-beta; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1; D048051:p38 Mitogen-Activated Protein Kinases