RESUMO
The gene encoding the large-T protein of polyoma virus (plt), the E1A genes of adenoviruses, the viral myc gene (v-myc) or rearranged forms of the cellular c-myc gene confer on rat embryo fibroblast (REF) cells in primary culture a series of new properties ('immortality', reduced serum requirement and sensitivity to transformation by viral and activated cellular oncogenes) but do not induce the appearance of transformed foci. We now report that focus formation can be induced after transfer of these genes into either REF or established FR3T3 rat cells by subsequent exposure to the tumour promoter 12-O-tetradecanoylphorbol 13-acetate (TPA). Frequencies of transformation are in the same range as those usually observed for transformation with complete polyoma DNA or with a mixture of cloned myc and ras oncogenes. These results further characterize the 'immortalized' state induced by plt and myc as one in which the cells maintain a normal growth control in many respects but can be further acted upon to produce a neoplastic progeny.
Assuntos
Transformação Celular Neoplásica/patologia , Transformação Celular Viral , Oncogenes , Forbóis/farmacologia , Polyomavirus/genética , Acetato de Tetradecanoilforbol/farmacologia , Animais , Divisão Celular , Linhagem Celular , Transformação Celular Neoplásica/efeitos dos fármacos , Embrião de Mamíferos , Fibroblastos , Genes Virais , Camundongos , RatosAssuntos
Transformação Celular Neoplásica , Oncogenes , Adenoviridae/genética , Animais , Carcinógenos , Células Cultivadas , Vírus de DNA/genética , Modelos Animais de Doenças , Embrião de Mamíferos , Fibroblastos , Genes Virais , Camundongos , Neoplasias/genética , Neoplasias/microbiologia , Fenótipo , Polyomavirus/genética , Ratos , Retroviridae/genéticaRESUMO
Uninfected and Rous sarcoma virus (RSV)-transformed chick embryo fibroblasts (CEF) were exposed to various concentrations of alpha-amanitin for different lengths of time. At a concentration of 4 micrograms alpha-amanitin/ml, RSV-transformed cells were shown to maintain a normal rate of transcription of all classes of RNA, whereas in uninfected cells transcription was reduced to a very low level. These observations cannot be accounted for by a difference in the penetration rate of alpha-amanitin through the plasma membrane. Investigation of the ultrastructure showed that the degree of nucleolar fragmentation induced by alpha-amanitin was comparable in both types of cells. Persistence of transcription with concomitant nucleolar fragmentation in alpha-amanitin-treated RSV-transformed CEF is not in accord with the hypothesis that nucleolar integrity is required for preribosomal RNA transcription.
Assuntos
Amanitinas/farmacologia , Vírus do Sarcoma Aviário , Nucléolo Celular/ultraestrutura , Transformação Celular Viral , RNA Ribossômico/biossíntese , Animais , Células Cultivadas , Embrião de Galinha , Microscopia Eletrônica , Precursores de Ácido Nucleico/biossíntese , Transcrição GênicaRESUMO
The number of polypeptides in highly purified preparations of RSV, of two different subgroups, produced in culture, has been compared to the polypeptides present in the supernatant of uninfected cultures and processed in identical manner. The analysis of PAGE-SDS shows that from 13 to 18 polypeptides present in viral preparations may be cellular contaminants. Fewer contaminating polypeptides are found in the myeloblastosis virus purified from plasma of Chicken.
