Characterization of nuclear factors involved in 202 gene induction by interferon-alpha in murine leukemia cells.
The 5' terminal flanking region of the interferon-inducible gene, 202, contains an interferon-stimulable response element (ISRE), called a GA box, that confers inducibility by interferon(IFN)-alpha, but not by IFN-gamma, on a reporter gene, such as the chloramphenicol acetyltransferase (CAT). Nuclear extracts from L1210 murine leukemia cells, stimulated for various periods of time with IFN-alpha, were mixed with 32P-labeled GA box and analyzed for the presence of retarded complexes in electrophoretic-mobility-shift assays. In addition to a few constitutive retarded complexes, an inducible GA box-binding activity (GAbf-1) appeared after 5 min, peaked at about 2 h, and was still abundant 12 h after IFN-alpha treatment. In the cytoplasmic fraction GAbf-1 was not detectable before 30 min, continued to increase up to 2 h, but had disappeared within 12 h. GAbf-1 activity was not observed in nuclear extracts treated with IFN-gamma, and was not inhibited by prior treatment with the protein-synthesis inhibitor cycloheximide. When the binding properties of GAbf-1 were compared with those of ISGF-3, the primary transcriptional activator for IFN-alpha-induced genes, a different pattern of retarded complexes was observed. Moreover, as observed by immunoblotting analysis, nuclear extracts from IFN-alpha-treated L1210 cells did not contain the p91/84 subunit of the ISGF3, the best characterized nuclear complex activated by IFN-alpha. Altogether these results indicate that GAbf-1 may be a novel transcription factor exploited by IFN-alpha to activate the 202 inducible gene in murine pre-B leukemia cells.
Gariglio
M
M
Institute of Microbiology, Medical School, University of Torino, Italy.
Gaboli
M
M
Mana
C
C
Ying
G G
GG
Gribaudo
G
G
Cavallo
R
R
Landolfo
S
S
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006367:HeLa Cells; D006801:Humans; D007370:Interferon Type I / Q000494:pharmacology*; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D007371:Interferon-gamma / Q000494:pharmacology; D007939:Leukemia L1210 / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism*; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C494227:IRF9 protein, human; D007370:Interferon Type I; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; C494228:Isgf3g protein, mouse; D011994:Recombinant Proteins; D014157:Transcription Factors; D007371:Interferon-gamma; D015500:Chloramphenicol O-Acetyltransferase