title: Expression of the viral thymidine kinase gene in herpes simplex virus-transformed L cells.
abstract: In these studies, the expression of thymidine kinase (TK) in normal and herpes simplex virus (HSV)-transformed L cells has been compared. In asynchronously dividing cultures of L cells, the TK activity rose and declined rapidly and coordinately with DNA synthesis. When net cell increase stopped, TK activity was at a minimum. In contrast, TK activity of HSV-transformed cells remained at a minimum during rapid DNA synthesis and gradually increased as the rate of DNA synthesis decreased. When net cell increase stopped, TK activity was at a maximum. In synchronous cultures of L cells, TK activity rose and fell coordinately with the rate of DNA synthesis. In synchronous cultures of HSV-transformed cells, no increase in TK activity was observed during the period of rapid DNA synthesis, i.e., the S phase. These findings indicated that the viral TK gene in HSV-transformed cells was not placed under the control of the cellular mechanisms which normally modulate the host cell TK gene. Lytic infection of HSV-transformed cells with a TK(-) mutant of HSV-1 induced a four-to fivefold increase in viral TK. The TK of HSV-1 was induced in the HSV-1-transformed cells and HSV-2 in the HSV-2-transformed cells by this TK(-) mutant. The same infection of normal L cells decreased the cellular TK activity by 80%. This stimulation, rather than inhibition, suggest that the viral gene in HSV-transformed cells retain some of its original viral characteristics.
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002458:Cell Fractionation; D002467:Cell Nucleus / Q000201:enzymology; D002471:Cell Transformation, Neoplastic; D003593:Cytoplasm / Q000201:enzymology; D004247:DNA / Q000096:biosynthesis; D004273:DNA, Neoplasm / Q000096:biosynthesis; D005796:Genes; D006918:Hydroxyurea / Q000494:pharmacology; D007739:L Cells / Q000201:enzymology*; D051379:Mice; D008928:Mitochondria / Q000201:enzymology; D009154:Mutation; D018139:Simplexvirus / Q000201:enzymology*; D013936:Thymidine / Q000378:metabolism; D013937:Thymidine Kinase / Q000096:biosynthesis*; D014316:Tritium
chemical_list: D004273:DNA, Neoplasm; D014316:Tritium; D004247:DNA; D013937:Thymidine Kinase; D013936:Thymidine; D006918:Hydroxyurea