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Inhibition of interferon-inducible gene expression by adenovirus E1A proteins: Block in transcriptional complex formation

Journal Article · · Proceedings of the National Academy of Sciences of the United States of America; (United States)

Infection with wild-type adenovirus 5, but not with a mutant lacking the E1A gene, prevented the induction by interferon (IFN) {alpha} of chloramphenicol acetyltransferase (CAT) activity in HeLaM cell lines that had been permanently transfected with chimeric CAT reporter genes driven by the transcriptional regulatory regions of the IFN-inducible CAT activity was observed in cells that were cotransfected with the same reporter genes and plasmids expressing either the E1A 289- or 243-amino acid protein. These proteins also prevented the induction of CAT activity by IFN-{gamma} from a cotransfected HLA-DR{alpha}-CAT gene. Experiments with E1A mutants mapped the inhibitory activity to amino acid residues 38-65 of these proteins. In a HeLa cell line permanently expressing the E1A 289-amino acid protein, the replication of vesicular stomatitis virus and encephalomyocarditis virus was not inhibited by IFN-{alpha}, suggesting a global blockade of IFN responses. The observed transcriptional inhibition could be attributed to the lack of formation of the crucial IFN-stimulated gene factor 3 (ISGF3) transcriptional complex. As shown by mobility shift assays, this complex was not formed in the nuclear extracts of IFN-treated adenovirus-infected cells or IFN-treated E1A-producing cells. These nuclear extracts were deficient in both ISGF3{alpha} and ISGF3{gamma} subunits. However, they did not block the formation of ISGF3 complex from exogenously added components.

OSTI ID:
5604232
Journal Information:
Proceedings of the National Academy of Sciences of the United States of America; (United States), Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (United States) Vol. 88:17; ISSN 0027-8424; ISSN PNASA
Country of Publication:
United States
Language:
English