Sp1 and NF-Y are necessary and sufficient for growth-dependent regulation of the hamster thymidine kinase promoter.
Thymidine kinase (TK) genes from different species are growth- and cell cycle-regulated in a very similar manner; still, the promoter regions of these genes show little homology to each other. It was previously shown that the murine TK gene is growth-regulated by Sp1 and E2F. Here we have characterized cis-regulatory elements in the hamster promoter that are essential and sufficient to confer efficient and serum-responsive expression. The TK promoter was isolated from baby hamster kidney cells. DNase I protection experiments revealed a protected region from positions -24 to -99 relative to the transcription start site. Within this region, binding sites for the transcription factor Sp1 and a CCAAT box, which interacts with the transcription factor NF-Y, were identified. An E2F-like sequence was found not to bind protein, and its removal did not affect promoter activity. This was supported by the observation that cotransfection of a hamster TK reporter gene construct with E2F-1 does not lead to transactivation of the promoter. A 122-base pair region that contains a single Sp1 site, a CCAAT box, and a TATA element was found to be sufficient for serum-responsive expression of a reporter gene. Mutations that inactivate any one of these three elements caused a strong reduction or a loss of promoter activity.
Sorensen
P
P
Institute of Molecular Biology, University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria.
Wintersberger
E
E
D020121:5' Untranslated Regions / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins; D002453:Cell Cycle; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D006224:Cricetinae; D004268:DNA-Binding Proteins / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007668:Kidney; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000096:biosynthesis; D017384:Sequence Deletion; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D013937:Thymidine Kinase / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
D020121:5' Untranslated Regions; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D013937:Thymidine Kinase