title: Enhancement of endogenous xenotropic murine retrovirus expression by tuftsin.
abstract: The exposure of a high-passage clone of Kirsten sarcoma virus transformed Balb/c (K-Balb) mouse cells to tuftsin (Thr-Lys-Pro-Arg) enhanced the expression of endogenous xenotropic retrovirus. The tetrapeptide increased the expression of virus that was infectious for rat, but not mouse, cells in a concentration-dependent fashion (0.001-1000 micrograms/ml). Increased virus expression could be achieved during short-term incubations (3-4 hr), with maximum enhancement occurring over longer time periods (16-18 hr). The enhancement of virus expression by tuftsin was proportional to the spontaneous release of virus. The infectivity of the enhanced virus was neutralized by goat anti-RLV gp 70 serum. Actinomycin D inhibited the induction of virus, suggesting that enhanced expression required de novo RNA synthesis. Tuftsin stimulated DNA, RNA, and protein synthesis in K-Balb cells during 16-hr incubations. Increased cellular proliferation was also seen at various time periods. The effects observed using K-Balb cells offer an opportunity to study the modulation of gene expression by tuftsin in a fibroblast culture system.
mesh_terms: D000818:Animals; D002415:Cats; D002460:Cell Line; D002999:Clone Cells / Q000382:microbiology; D003513:Cycloheximide / Q000494:pharmacology; D004279:DNA, Viral / Q000096:biosynthesis; D003609:Dactinomycin / Q000494:pharmacology; D007065:Idoxuridine / Q000494:pharmacology; D007708:Kirsten murine sarcoma virus / Q000254:growth & development*; D051379:Mice; D008807:Mice, Inbred BALB C; D008907:Mink; D014176:Protein Biosynthesis; D012367:RNA, Viral / Q000096:biosynthesis; D051381:Rats; D009053:Sarcoma Viruses, Murine / Q000254:growth & development*; D014405:Tuftsin / Q000494:pharmacology*; D014775:Virus Activation / Q000187:drug effects
chemical_list: D004279:DNA, Viral; D012367:RNA, Viral; D003609:Dactinomycin; D003513:Cycloheximide; D007065:Idoxuridine; D014405:Tuftsin