Article: article from journal or magazin.
Interferon induction of gene transcription analyzed by in vivo footprinting
Molecular Cell Biology
Journal Article Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S. --- Old month value: Jan
The promoters of two interferon-induced genes (the ISG54 and guanylate-binding protein [GBP] genes) have been analyzed in whole cells and in isolated nuclei by using a new genomic sequencing technique. The ISG54 gene contains an interferon-simulating response element (ISRE), earlier shown to be necessary and sufficient for alpha interferon (IFN-alpha) induction, that appeared complexed with proteins in both transcribing and nontranscribing cells. However, the extent of protection and hypersensitivity to DNase I or dimethyl sulfate within the ISRE region was changed upon transcriptional induction, suggesting the binding of different factors in different transcriptional states. In addition to the ISRE, the GBP gene needs a newly recognized DNA element, called the GAS, that partly overlaps the ISRE for full induction by either IFN-alpha or IFN-gamma. This GAS element was transiently protected against DNase I in the nuclei of interferon-treated cells but was not protected at later times when transcription reached maximal levels. Thus, the GAS-binding activity may be necessary only transiently for the initial assembly of a transcription initiation complex on the GBP promoter. Dimethyl sulfate methylation of genomic DNA performed on intact cells showed a characteristic sensitivity over the GAS that correlated with transcription levels and that persisted longer than did DNase I protection over the GAS. These results demonstrate the involvement of the GAS in IFN-alpha and -gamma induction of GBP and suggest the presence of an altered DNA conformation or a small protein in the major groove of the GAS associated with ongoing GBP transcription.
Base Sequence Cell Line Dna Deoxyribonuclease I/metabolism GTP-Binding Proteins/*genetics *Gene Expression Regulation Hela Cells Humans Interferon Type II/*physiology Interferon-alpha/*physiology Molecular Sequence Data Promoter Regions (Genetics) Regulatory Sequences, Nucleic Acid Sulfuric Acid Esters/pharmacology TATA Box *Transcription, Genetic
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