title: Induction of transgene expression in Tg.AC(v-Ha-ras) transgenic mice concomitant with DNA hypomethylation.
abstract: Tg.AC transgenic mice have a transgene composed of a zeta-globin transcriptional control region, a v-Ha-ras coding region, and a simian virus 40 3' polyadenylation signal sequence. Induced ectopic expression of the transgene by chemical treatment or full-skin-thickness wounding leads to the development of skin papillomas. Reverse transcription-polymerase chain reaction assays and protein blotting indicated that the transgene was expressed 16-28 d after full-skin-thickness surgical wounding. Normal unwounded skin did not express the transgene. DNA blotting indicated that the position of the transgene remained stable during wound-induced tumorigenesis. Concomitant with the v-Ha-ras mRNA and protein expression was the hypomethylation of specific MspI/HpaII sites within the transgene. These results are consistent with the hypothesis that hypomethylation is required for the induced and sustained expression of the Tg.AC v-Ha-ras transgene in spontaneous and induced tumors in Tg.AC mice.
authors.affiliation: Laboratory of Environmental Carcinogenesis and Mutagenesis, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Cannon
authors.forename: J W
authors.initials: JW
authors.lastname: Spalding
authors.forename: K M
authors.initials: KM
authors.lastname: Virgil
authors.forename: R S
authors.initials: RS
authors.lastname: Faircloth
authors.forename: M C
authors.initials: MC
authors.lastname: Humble
authors.forename: G D
authors.initials: GD
authors.lastname: Lacks
authors.forename: R W
authors.initials: RW
authors.lastname: Tennant
mesh_terms: D000818:Animals; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D019175:DNA Methylation; D005260:Female; D005786:Gene Expression Regulation; D011905:Genes, ras; D005914:Globins / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D015689:Oncogene Protein p21(ras) / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D010212:Papilloma / Q000209:etiology / Q000235:genetics*; D016133:Polymerase Chain Reaction; D013539:Simian virus 40 / Q000235:genetics; D012867:Skin / Q000293:injuries*; D012878:Skin Neoplasms / Q000209:etiology / Q000235:genetics*; D014158:Transcription, Genetic; D019076:Transgenes; D014945:Wound Healing / Q000235:genetics*; D014947:Wounds and Injuries / Q000150:complications
chemical_list: D005914:Globins; D015689:Oncogene Protein p21(ras)