Transcriptional regulation of the interleukin-6 gene in mesangial cells.
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.
Grassl
C
C
Medizinische Poliklinik, Klinikum Innenstadt der Ludwig-Maximilians-Universität, Munich, Germany.
Luckow
B
B
Schlöndorff
D
D
Dendorfer
U
U
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D022762:CCAAT-Enhancer-Binding Proteins; D002460:Cell Line; D000242:Cyclic AMP / Q000819:agonists / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D015342:DNA Probes / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D017930:Genes, Reporter / Q000187:drug effects; D005920:Glomerular Mesangium / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D007375:Interleukin-1 / Q000494:pharmacology; D015850:Interleukin-6 / Q000235:genetics* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism
D022762:CCAAT-Enhancer-Binding Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D015342:DNA Probes; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D007375:Interleukin-1; D015850:Interleukin-6; D008070:Lipopolysaccharides; D016328:NF-kappa B; D009687:Nuclear Proteins; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases