An element binding a C/EBP-related transcription factor contributes to negative regulation of the bovine papillomavirus type 4 long control region.
Deletion of the NR2 element of the long control region (LCR) of bovine papillomavirus type 4 (BPV-4) was observed previously to lead to a fivefold increase in enhancer activity of a subfragment of the LCR. Further characterization of this element indicates that mutations in NR2 lead to increased enhancer activity in both mouse CT3 fibroblasts and in a transformed bovine epithelial cell line derived from an alimentary canal papilloma/in situ carcinoma, but not in primary bovine keratinocytes. Since similar oligonucleotide-nuclear factor complexes were obtained in electrophoretic mobility shift assays (EMSA) for all three cell types, the observed difference in negative activity may result from variation in the NR2-binding factor itself between primary and established/transformed cell lines, or from the involvement of other factors that vary between the lines. Characterization of the NR2-binding factor by heat stability and antibody supershifts in EMSA indicate that the factor is related to the CCAAT/enhancer-binding protein (C/EBP) family, and that one component of the complexes may be C/EBP beta.
McCaffery
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Beatson Institute for Cancer Research, CRC Beatson Laboratories, Bearsden, Glasgow, U.K.
Jackson
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D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D052688:Bovine papillomavirus 1 / Q000235:genetics*; D052697:Bovine papillomavirus 4; D022762:CCAAT-Enhancer-Binding Proteins; D002467:Cell Nucleus / Q000378:metabolism; D002999:Clone Cells; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D015967:Gene Expression Regulation, Viral; D016679:Genome, Viral; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D012091:Repetitive Sequences, Nucleic Acid; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D014157:Transcription Factors