title: Tumor necrosis factor alpha inhibits transcriptional activity of the porcine P-45011A insulin-like growth factor response element.
abstract: We investigated the effects of tumor necrosis factor alpha (TNFalpha) on the transcriptional activity of the porcine P-45011A (P450scc) insulin-like growth factor response element (IGFRE). TNFalpha inhibited insulin-like growth factor-I (IGF-I)-stimulated P450scc mRNA concentrations in cultures of porcine granulosa cells. Transient transfection experiments in granulosa cells with deletion P450scc/luciferase constructs showed that TNFalpha inhibited the transcriptional activity of the IGFRE. IGF-I binding and IGF-I receptor mRNA concentrations in porcine granulosa cells were not inhibited by TNFalpha. Electrophoretic mobility shift assay with nuclear extract protein from porcine granulosa cells treated with IGF-I and TNFalpha showed that Sp1 and a second transcription factor, P2, bound to the IGFRE. While IGF-I treatment increased the binding activity of both factors, TNFalpha specifically inhibited the IGF-I-stimulated binding activity of P2. Transient transfection studies done in mouse fibroblasts overexpressing the IGF-I receptor (NWTb3) with the porcine IGFRE (three repeats) in an SV40/luciferase construct also showed TNFalpha inhibited IGF-I-stimulated reporter gene expression. We conclude that TNFalpha inhibits the transcriptional activity of the porcine P450scc IGFRE by preventing IGF-I-stimulated binding of P2.
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, Texas 77555-0587, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Urban
authors.forename: M
authors.initials: M
authors.lastname: Nagamani
authors.forename: Y
authors.initials: Y
authors.lastname: Bodenburg
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006107:Granulosa Cells / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D051379:Mice; D011374:Progesterone / Q000096:biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism; D016329:Sp1 Transcription Factor / Q000378:metabolism; D013552:Swine; D014158:Transcription, Genetic / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D012333:RNA, Messenger; D016329:Sp1 Transcription Factor; D014409:Tumor Necrosis Factor-alpha; D011374:Progesterone; D007334:Insulin-Like Growth Factor I; D002786:Cholesterol Side-Chain Cleavage Enzyme; D017526:Receptor, IGF Type 1