Transcriptional repression of interleukin-6 gene by adenoviral E1A proteins.
Transcription of interleukin-6 (IL-6) gene in human HepG2 and HeLa cells was induced by treatment with interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-alpha), phorbol 12-myristate 13-acetate, or dibutyryl cyclic AMP. These agents enhanced the expression of chloramphenicol acetyltransferase (CAT) activity in cells transfected with chimeric CAT genes driven by the transcriptional regulatory regions of human IL-6 gene. Both induced and basal levels of CAT expression were severely repressed upon co-transfection of expression vectors encoding the adenoviral E1A289R or E1A243R protein. The conserved region 1 of E1A proteins was required for this activity. IL-6-CAT expression could also be induced by co-transfecting expression vectors containing cDNAs of the catalytic subunit of protein kinase A or c-jun. E1A repressed transcriptional induction by these agents as well. Similar inhibition was observed when a CAT gene driven by the NF kappa B element of the IL-6 gene was used as a reporter plasmid. In a cell line stably transfected with the E1A gene, IL-1 or TNF-alpha failed to induce IL-6 mRNA. Electrophoretic mobility shift assays were carried out with nuclear extracts of these cells using, as probes, the NF kappa B element or the multiple regulatory element of the IL-6 gene. With either probe, additional faster migrating DNA-protein complexes were formed in the extracts of E1A-expressing cells as compared with the extracts of the corresponding control cells. Experiments with NF kappa B antibody revealed differences between the different DNA-protein complexes formed in the extract of E1A-expressing cells. These observations suggest that E1A represses IL-6 gene transcription by interfering with the formation of appropriate DNA-protein complexes.
Janaswami
P M
PM
Department of Molecular Biology, Cleveland Clinic Foundation, Ohio 44195-5285.
Kalvakolanu
D V
DV
Zhang
Y
Y
Sen
G C
GC
D017500:Adenovirus E1A Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D003994:Bucladesine / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D015850:Interleukin-6 / Q000235:genetics*; D008113:Liver Neoplasms; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D009838:Oligodeoxyribonucleotides; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013937:Thymidine Kinase / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D017500:Adenovirus E1A Proteins; D007375:Interleukin-1; D015850:Interleukin-6; D016328:NF-kappa B; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; D014409:Tumor Necrosis Factor-alpha; D003994:Bucladesine; D004247:DNA; D000242:Cyclic AMP; D015500:Chloramphenicol O-Acetyltransferase; D013937:Thymidine Kinase; D013755:Tetradecanoylphorbol Acetate