RESUMO
Molecular analysis has shown that the majority of Abelson murine leukemia virus (Ab-MuLV)-induced primary thymomas represent transformed gamma/delta thymocytes. Many of these thymomas are of monoclonal origin as judged by provirus integration pattern and contain rearranged genes encoding T-cell receptor (TCR) gamma and delta chains but germ-line immunoglobulin heavy-chain genes. Some of the monoclonal tumors contain multiple rearranged alleles encoding TCR gamma, delta, and beta chains. Further, one Ab-MuLV thymoma cell line contained germ-line-configuration TCR gamma- and delta-chain genes, which became rearranged after in vitro propagation. Clones of this cell line were observed to rearrange these genes after intrathymic passage. Also, some subclones of this cell line underwent rearrangement of their immunoglobulin heavy-chain genes in culture. These observations suggest that the thymic targets for Ab-MuLV transformation are early gamma/delta thymocytes, some of which continue to rearrange their TCR gamma- and delta-chain genes.
Assuntos
Vírus da Leucemia Murina de Abelson/crescimento & desenvolvimento , Rearranjo Gênico do Linfócito T , Subpopulações de Linfócitos T/microbiologia , Timoma/genética , Timo/microbiologia , Neoplasias do Timo/genética , Animais , Southern Blotting , Rearranjo Gênico de Cadeia Pesada de Linfócito B/genética , Cadeias Pesadas de Imunoglobulinas/genética , Camundongos , Camundongos Endogâmicos C57BL , Receptores de Antígenos de Linfócitos T/genética , Receptores de Antígenos de Linfócitos T gama-delta , Timoma/microbiologia , Timo/citologia , Neoplasias do Timo/microbiologiaRESUMO
The Drosophila melanogaster abl and the murine v-abl genes encode tyrosine protein kinases (TPKs) whose amino acid sequences are highly conserved. To assess functional conservation between the two gene products, we constructed Drosophila abl/v-abl-chimeric Abelson murine leukemia viruses. In these chimeric Abelson murine leukemia viruses, the TPK and carboxy-terminal regions of v-abl were replaced with the corresponding regions of D. melanogaster abl. The chimeric Abelson murine leukemia viruses were able to mediate morphological and oncogenic transformation of NIH 3T3 cells and were able to abrogate the interleukin-3 dependence of a lymphoid cell line. We also found that a virus that contained both TPK and carboxy-terminal Drosophila abl regions had no in vitro transforming activity for primary bone marrow cells and lacked the ability to induce tumors in susceptible mice. A virus that replaced only a portion of the v-abl TPK region with that of Drosophila abl had low activity in in vitro bone marrow transformation and tumorigenesis assays. These results indicate that the transforming functions of abl TPKs are only partially conserved through evolution. These results also imply that the TPK region of v-abl is a major determinant of its efficient lymphoid cell-transforming activity.
Assuntos
Vírus da Leucemia Murina de Abelson/genética , Transformação Celular Neoplásica , Drosophila melanogaster/genética , Vírus da Leucemia Murina/genética , Proteínas Tirosina Quinases/genética , Proteínas Virais/genética , Sequência de Aminoácidos , Animais , Células da Medula Óssea , Células Cultivadas , Quimera , Sondas de DNA , DNA Viral/genética , Camundongos , Camundongos Endogâmicos BALB C , Dados de Sequência Molecular , Mapeamento por Restrição , Homologia de Sequência do Ácido Nucleico , TransfecçãoAssuntos
Oncogenes/fisiologia , Vírus da Leucemia Murina de Abelson/genética , Animais , Transformação Celular Neoplásica , Transformação Celular Viral , Regulação da Expressão Gênica , Humanos , Proteínas Tirosina Quinases/genética , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas c-abl , Proteínas Proto-Oncogênicas p21(ras) , RNA Mensageiro/genética , RNA Viral/genética , Proteínas Oncogênicas de Retroviridae/genéticaRESUMO
Nucleotide sequence analysis of the cellular sequences flanking the integrated ecotropic (mouse-infectious) murine leukemia provirus of BALB/c mice indicated that the murine leukemia provirus is integrated in opposing transcriptional orientation within a solo long terminal repeat (LTR) of the VL30 family of endogenous retrovirus-related sequences. To quantify the effect of this integration event on the ability of the ecotropic provirus to be expressed, we constructed recombinant molecules that carried the chloramphenicol acetyltransferase (cat) gene and various viral LTRs and determined the CAT activity induced by these constructs after transfection of NIH 3T3 cells. Our results indicate that the BALB/c ecotropic LTR is about 10-fold more active than the VL30 LTR. The presence of the VL30 LTR did not affect the transcriptional activity of the ecotropic LTR in the context of the integration event. Our results also indicate that the LTRs of the BALB/c provirus are less transcriptionally active than are the proviral LTRs of AKR murine leukemia virus and the Harvey murine sarcoma virus.
Assuntos
Transformação Celular Viral , Vírus da Leucemia Murina/genética , Animais , DNA Viral/genética , Elementos Facilitadores Genéticos , Regulação da Expressão Gênica , Camundongos , Camundongos Endogâmicos AKR , Camundongos Endogâmicos BALB C , Recombinação Genética , Sequências Repetitivas de Ácido Nucleico , Transcrição GênicaAssuntos
Vírus da Leucemia Murina de Abelson/patogenicidade , Transformação Celular Neoplásica , Vírus da Leucemia Murina/patogenicidade , Leucemia Experimental/microbiologia , Linfoma/microbiologia , Vírus da Leucemia Murina de Abelson/genética , Animais , Animais Recém-Nascidos , Enzimas de Restrição do DNA , CamundongosRESUMO
Nucleotide content of normal and Bloom's syndrome fibroblasts and lymphocytes were examined by reversed phase HPLC. The ATP/ADP ratio in primary cultures of normal human fibroblasts was at least three fold higher than in the primary cultures of Bloom's syndrome fibroblasts. After three months in culture the ratios of ATP/ADP of the Bloom's cells approach those of normal fibroblasts. Individual nucleotide measurements showed that initial differences did not reflect excess ADP, but rather very low levels of ATP in Bloom's syndrome fibroblasts. The amount of ATP increased gradually during culture. However, even after three months in culture, significant differences were noted in ATP levels between Bloom's syndrome fibroblasts and normal fibroblasts. Thus a defect in Bloom's syndrome is correlated with a defect in purine biosynthesis or ATP generation.