Transcriptional regulation of the interleukin-6 gene in mesangial cells

• Published in: Journal of the American Society of Nephrology 1999-07, Vol.10 (7), p.1466-1477
• Main Authors: GRASSL, C, LUCKOW, B, SCHLONDORFF, D, DENDORFER, U
• Format: Article
• Language: English
• Subjects: 8-Bromo Cyclic Adenosine Monophosphate - pharmacology; Animals; Base Sequence; Binding Sites - genetics; Biological and medical sciences; CCAAT-Enhancer-Binding Proteins; Cell Line; Cyclic AMP - agonists; Cyclic AMP - metabolism; Cyclic AMP Response Element-Binding Protein - metabolism; Cyclic AMP-Dependent Protein Kinases - antagonists & inhibitors; Cyclic AMP-Dependent Protein Kinases - metabolism; DNA Probes - genetics; DNA-Binding Proteins - metabolism; Enzyme Inhibitors - pharmacology; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation; Genes, Reporter - drug effects; Glomerular Mesangium - drug effects; Glomerular Mesangium - immunology; Glomerular Mesangium - metabolism; Interleukin-1 - pharmacology; Interleukin-6 - genetics; Interleukin-6 - metabolism; Lipopolysaccharides - pharmacology; Mice; NF-kappa B - metabolism; Nuclear Proteins - metabolism; Promoter Regions, Genetic; RNA, Messenger - genetics; RNA, Messenger - metabolism; Transcription Factor AP-1 - metabolism; Vertebrates: urinary system
• ISSN: 1046-6673; 1533-3450
• DOI: 10.1681/asn.v1071466

Cytokine secretion by mesangial cells (MC) plays a major role in the pathogenesis of glomerulonephritis. To define signaling events that occur during the activation of MC, the cell-specific transcriptional regulation of the interleukin-6 (IL-6) gene was studied. Stimulation with lipopolysaccharide and IL-1beta resulted in the full induction of IL-6 expression only if the cells were coincubated with cAMP agonists; this effect was attenuated by protein kinase A inhibitors. In reporter gene experiments, the IL-6 promoter showed a stimulation pattern comparable to that of the endogenous gene. Elimination of individual transcription factor binding sites provided evidence for functional roles for four cis-acting elements, i.e., activator protein-1, cAMP response element-binding protein (CREB), nuclear factor for IL-6 expression (NF-IL6), and nuclear factor-kappaB (NF-kappaB). Electrophoretic mobility shift assays using nuclear extracts from MC revealed that the DNA-binding activities of activator protein-1 and NF-KB were inducible, whereas no change could be observed for CREB and NF-IL6. The presence of several transcription factor proteins, including JunB, JunD, c-Fos, Fra-1, CREB-1, activating transcription factor-2, NF-KB p50, p52, and p65, and CAAT/enhancer-binding protein-delta, was demonstrated by supershift analysis. Of particular interest was the novel finding of the participation of NF-kappaB p65 in the NF-IL6 complex. In summary, a signal transduction pathway in MC that requires protein kinase A activation in addition to a second signal provided by lipopolysaccharide or IL-1beta was identified.