Characterization of the nuclear factors involved in 202 gene induction by IFN-alpha in NIH-3T3 cells.
When treated with IFN-alpha, NIH-3T3 cells express after a few hours high levels of the mouse 202 gene mRNA. This activation takes place at the transcriptional level as shown by nuclear "run on" assay. For this purpose a fragment of 806 base-pairs (the b fragment), spanning the 5'-flanking region of the 202 gene, was linked to the reporter CAT gene and transiently transfected into mouse NIH 3T3. The data suggest that the b fragment is sufficient to confer transcriptional inducibility upon IFN stimulation and can account in large part for the response of the 202 gene. Binding assays, using a 40-bp probe derived from the IFN-stimulated response element (ISRE) comprised in the b fragment, demonstrated the presence of two DNA-binding proteins. One of these, defined as complex A, was inducible upon IFN treatment, whereas the other, defined as complex B, was constitutively present regardless of IFN treatment. The IFN-alpha-induced complex A appears to have the necessary characteristics to be the transcriptional activator of the 202 gene: it requires the same nucleotides for binding as are required for IFN-dependent gene activation and is dependent on IFN-alpha treatment.
Gariglio
G
G
Institute of Microbiology, Medical School, University of Torino, Italy.
Panico
S
S
Gribaudo
G
G
Martinotti
M G
MG
Cavallo
G
G
Landolfo
S
S
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D015342:DNA Probes; D004268:DNA-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D007370:Interferon Type I / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins; D014158:Transcription, Genetic / Q000187:drug effects; D015533:Transcriptional Activation
D015342:DNA Probes; D004268:DNA-Binding Proteins; D007370:Interferon Type I; D009687:Nuclear Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins