SV40 large T antigen transactivates the human cdc2 promoter by inducing a CCAAT box binding factor.
Cyclin-dependent protein kinases (Cdks) play a key role in the cell division cycle of eukaryotic cells. Cdc2, the first mammalian Cdk that was discovered, is expressed in S phase and functions in the G2 to M phase transition. By transfecting segments of the human cdc2 promoter linked to a reporter gene into monkey kidney (CV-1) cells, we identified the region containing the Sp1, E2F, and two CCAAT box binding sites as essential and sufficient for basal transcription. SV40 large T antigen (SV40-LT) is a viral oncoprotein that transactivates viral and cellular promoters and induces DNA synthesis in quiescent cells. SV40-LT transactivated wild-type cdc2 promoter/reporter constructs in a dose-dependent manner, coinciding with an increase in endogenous cdc2 mRNA. A mutant promoter from which the two CCAAT box motifs were deleted was 8-fold less sensitive to SV40-LT. Activation by SV40-LT did not require its ability to bind the retinoblastoma or p53 tumor suppressor proteins. SV40-LT induced a specific CCAAT box-binding factor (CBF) in CV-1 and COS-7 cells, as judged by gel shift and Southwestern analyses. Similar results were obtained in human fibroblasts expressing a conditional SV40-LT. The SV40-LT-inducible CBF appears to be novel and differs from the CBF that activates heat shock protein 70 gene expression.
Chen
H
H
Department of Biochemistry and Molecular Biology, the University of Kansas Medical Center, Kansas City, Kansas 66160-7421, USA.
Campisi
J
J
Padmanabhan
R
R
D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins; D016203:CDC2 Protein Kinase / Q000096:biosynthesis* / Q000235:genetics*; D002460:Cell Line; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D006801:Humans; D007668:Kidney; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis; D017384:Sequence Deletion; D013539:Simian virus 40 / Q000276:immunology*; D014157:Transcription Factors / Q000096:biosynthesis; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
D000952:Antigens, Polyomavirus Transforming; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D016203:CDC2 Protein Kinase