title: Cloned mouse mammary tumor virus DNA is biologically active in transfected mouse cells and its expression is stimulated by glucocorticoid hormones.
abstract: We have cloned circular unintegrated mouse mammary tumor virus (MMTV) DNA from infected rat hepatoma cells in bacteriophage lambda. Seven independent clones containing MMTV DNA of homogeneous length of 9 kb (five) or 10 kb (two) were identified. The five 9 kb clones had identical restriction maps consistent with that of 9 kb unintegrated DNA; the other two were aberrant. MMTV DNA inserts were purified, ligated and used for cotransfection of Ltk- cells together with a plasmid containing the thymidine kinase gene of herpes simplex virus. All Tk+ cell clones acquired new MMTV sequences and those transfected with the 9 kb MMTV DNA synthesized normal viral RNA and proteins. Viral gene expression was increased by the addition of dexamethasone.
mesh_terms: D000818:Animals; D002460:Cell Line; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004279:DNA, Viral / Q000032:analysis; D003907:Dexamethasone / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics*; D051379:Mice; D012367:RNA, Viral / Q000032:analysis; D014162:Transfection; D014764:Viral Proteins / Q000096:biosynthesis
chemical_list: D004279:DNA, Viral; D012367:RNA, Viral; D014764:Viral Proteins; D003907:Dexamethasone; D004262:DNA Restriction Enzymes