Stable reduction of thymidine kinase activity in cells expressing high levels of anti-sense RNA.
Anti-sense thymidine kinase (TK) RNA was expressed as part of a chimeric dihydrofolate reductase (DHFR) anti-sense TK transcript. High level expression was obtained by selection of cells resistant to progressively higher levels of methotrexate, provided by overproduction of DHFR. The result was a concomitant increase in intracellular anti-sense TK RNA level owing to its presence on the same transcription unit as DHFR. In several cell lines expressing high levels of anti-sense TK RNA, thymidine kinase activity was reduced by 80%-90%. RNA:RNA duplexes were detected in the nuclear fraction. The results suggest a mechanism for diminution of TK activity; anti-sense RNA hybridizes with sense TK RNA in the nucleus, and duplex containing TK transcripts fail to enter the cytoplasm with normal efficiency.
S K
SK
Kim
B J
BJ
Wold
D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004351:Drug Resistance; D005784:Gene Amplification; D007739:L Cells; D008727:Methotrexate / Q000494:pharmacology; D009693:Nucleic Acid Hybridization; D012313:RNA / Q000096:biosynthesis / Q000235:genetics*; D018075:RNA, Complementary; D012330:RNA, Double-Stranded / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013762:Tetrahydrofolate Dehydrogenase / Q000096:biosynthesis / Q000235:genetics; D013937:Thymidine Kinase / Q000096:biosynthesis / Q000235:genetics*; D014158:Transcription, Genetic
D018075:RNA, Complementary; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D012313:RNA; D013762:Tetrahydrofolate Dehydrogenase; D013937:Thymidine Kinase; D008727:Methotrexate