Regulation of the expression of the SV40 T-antigen coding gene under the control of an rDNA promoter.
We have constructed a hybrid gene in which the SV40 T-antigen coding gene is driven by a mouse rDNA promoter and we have compared its expression to that of an SV40 T-antigen coding gene under the control of its own promoter. The comparison has been carried out in microinjected cells, in transfected cells, and in stable cell lines carrying the respective T-antigen coding genes in an integrated form. These cell lines were derived from ts AF8 cells, a mutant which is temperature sensitive for RNA polymerase II activity. The hybrid gene clearly expresses T-antigen, albeit less efficiently than when the T antigen coding gene is under the control of the SV40-promoter. We also show that the expression of T-antigen by the hybrid gene is 50% inhibited by an antibody against RNA polymerase I. In tsAF8 cells carrying the hybrid gene, T-antigen is still expressed at the restrictive temperature (where RNA polymerase II is inactive) at a level again about 50% of controls. However, our findings also confirm those of Smale and Tjian (Mol. Cell. Biol. 5:352, 1985) that such hybrid genes are in part transcribed by RNA polymerase II and generate abnormal transcripts.
D000818:Animals; D000952:Antigens, Polyomavirus Transforming; D000957:Antigens, Viral, Tumor / Q000235:genetics*; D002460:Cell Line; D006224:Cricetinae; D004275:DNA, Ribosomal / Q000502:physiology*; D004720:Endonucleases / Q000378:metabolism; D005786:Gene Expression Regulation; D008647:Mesocricetus; D051379:Mice; D008845:Microinjections; D009154:Mutation; D009856:Oncogene Proteins, Viral / Q000235:genetics*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012318:RNA Polymerase I / Q000276:immunology; D012319:RNA Polymerase II / Q000378:metabolism; D013539:Simian virus 40 / Q000235:genetics; D015719:Single-Strand Specific DNA and RNA Endonucleases; D013696:Temperature; D014162:Transfection
D000952:Antigens, Polyomavirus Transforming; D000957:Antigens, Viral, Tumor; D004275:DNA, Ribosomal; D009856:Oncogene Proteins, Viral; D012319:RNA Polymerase II; D012318:RNA Polymerase I; D004720:Endonucleases; D015719:Single-Strand Specific DNA and RNA Endonucleases