Renal CCAAT/enhancer-binding proteins in experimental diabetes mellitus.
There is evidence that mediators of inflammation including components of the cytokine system are present in human and experimental diabetic kidney disease. CCAAT/enhancer-binding proteins (C/EBPs) represent a family of cytokine-inducible transcription factors. C/EBPs themselves regulate cytokine expression and also the expression of acute-phase reactants and connective tissue proteins. At least three C/EBP isoforms (alpha, beta, delta) are known. Upon stimulation with cytokines or bacterial lipopolysaccharide, the expression of the alpha isoform typically decreases, and the expression of the beta and/or delta isoforms increases. In view of the fact that components of the inflammatory response are present in diabetic kidney disease, there is a potential that the expression and activity of renal C/EBPs are altered in the diabetic state. In this study we sought to examine the status of C/EBP proteins in kidneys of rats with streptozotocin-induced diabetes mellitus. Diabetes was induced in 5 male Sprague-Dawley rats. Eight weight-matched non-diabetic rats were used as controls. Animals were sacrificed after 4 weeks, and the whole kidney nuclear protein was extracted. An electrophoretic mobility shift assay showed that DNA-binding activity was present in all five kidney nuclear extracts of the diabetic animals, but in only 2 out of 8 control samples (p < 0.05). A supershift assay showed that the DNA-bound protein complex consisted mainly of the C/EBPbeta isoform. Western analysis showed an increase of the C/EBPbeta protein in renal nuclear extracts of the diabetic animals compared to controls (p < 0.05). There was a decrease of the C/EBPalpha protein in the kidney nuclear extracts of the diabetic animals compared to controls (p < 0.05). We conclude that renal C/EBP dynamics are altered in experimental diabetes mellitus and that the patterns of C/EBP changes resemble those observed after cytokine or lipopolysaccharide stimulation.
Department of Pediatrics, University of Texas Medical Branch, Galveston, USA.
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Zador
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Hsieh
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Papaconstantinou
D000818:Animals; D001786:Blood Glucose; D015153:Blotting, Western; D022762:CCAAT-Enhancer-Binding Proteins; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D007668:Kidney / Q000737:chemistry* / Q000378:metabolism; D008297:Male; D009687:Nuclear Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism*; D015345:Oligonucleotide Probes; D051381:Rats; D017207:Rats, Sprague-Dawley; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics / Q000378:metabolism
D001786:Blood Glucose; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D015345:Oligonucleotide Probes; D014157:Transcription Factors; D004247:DNA