7S-K Nuclear RNA from Simian Virus 40-Transformed Cells Has Sequence Homology to the Viral Early Promoter

• Published in: Proceedings of the National Academy of Sciences - PNAS 1983-12, Vol.80 (23), p.7090-7094
• Main Authors: Sohn, Uik, Szyszko, Jolanta, Coombs, David, Krause, Margarida
• Format: Article
• Language: English
• Subjects: 3T3 cells; Animals; Base Sequence; Cell lines; Cell nucleus; Cell Transformation, Viral; Cells, Cultured; DNA; Gels; Genes; Genetic hybridization; Mice; Molecular Weight; Nucleic Acid Hybridization; Operon; Promoter regions; Protein Biosynthesis; RNA; RNA - genetics; RNA - isolation & purification; RNA, Small Nuclear; Simian virus 40 - genetics; Small nuclear RNA
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.80.23.7090

Previous findings in our laboratory have identified a specific small nuclear RNA (7S-K) that promotes transcription initiation by RNA polymerase II in isolated mammalian nuclei. The present study was designed to investigate the homology between 7S-K RNAs and host and viral sequences in simian virus 40 (SV40)-transformed and in untransformed mouse 3T3 cells, with the object of testing the hypothesis that these RNAs take part in the transcription initiation complex by base pairing to promoter/enhancer regions of active genes. DNA· RNA hybridization experiments, using either Southern or RNA blotting techniques, indicated that both 7S-K and 7S-L RNAs hybridize to midrepetitive fractions of the mouse genome. However, only 7S-K RNA from transformed cells hybridized to SV40 DNA. Restriction mapping and nuclease S1 treatment of the hybridized region of SV40 yielded a 45-nucleotide-long hybrid duplex. Partial sequence analysis of the 5′end of the DNA in this duplex revealed sequence homology with the 21-base-pair repeat sequence, identified as the SV40 early promoter. Because the viral early gene is expressed in transformed cells, we conclude that 7S-K RNAs in these cells contain a species that has sequence homology to a promoter of an active gene. Taking these results together with previous ones, we postulate that the observed stimulatory activity of 7S-K RNA on transcription initiation is due to its recognition of promoter sequences, either to facilitate the formation or as part of the transcription initiation complex.