Inefficient expression in rat cells of transforming gene of BK virus with 68-bp tandem repeats in the viral promoter-enhancer.
Large-plaque BK virus (wt-501), which has three 68-bp tandem repeats in the viral promoter-enhancer, is not transforming for rat cells, whereas the minute-plaque mutant (dl-504) with only one 68-bp element is. We tested the BKV wt-501 and dl-504 promoter-enhancers for their ability to activate the heterologous and homologous genes in rat 3Y1 cells. The 501 promoter-enhancer activated expression of the chloramphenicol acetyltransferase gene and the neomycin-resistance gene more efficiently than the 504 promoter-enhancer. The 501 enhancer could not allow the efficient expression of BK virus T-antigen gene, whereas the 504 enhancer could. The wt-BKV enhancer with three 68-bp repeats seemed to function positively on the heterologous genes but negatively on the homologous transforming gene in rat cells. The sequence causing the suppressive effects by duplication was confined within the 29-bp segment containing two SV40 enhancer core homologies in the 68-bp element. The results show that inability of wt-BKV to transform rat cells is ascribable to inefficient T-antigen gene expression caused by the duplication in the enhancer and by the surrounding or downstream DNA sequence.
Watanabe
S
S
Department of Enteroviruses, National Institute of Health, Tokyo, Japan.
Yoshiike
K
K
D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics; D001739:BK Virus / Q000235:genetics*; D001483:Base Sequence; D015139:Blotting, Southern; D002460:Cell Line; D002472:Cell Transformation, Viral; D004279:DNA, Viral / Q000235:genetics; D004742:Enhancer Elements, Genetic; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D005814:Genes, Viral; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009857:Oncogenes; D010957:Plasmids; D011120:Polyomavirus / Q000235:genetics*; D011401:Promoter Regions, Genetic; D051381:Rats; D012091:Repetitive Sequences, Nucleic Acid; D014162:Transfection
D000952:Antigens, Polyomavirus Transforming; D004279:DNA, Viral