RESUMO
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 , TransfecçãoRESUMO
We report our molecular characterization of the Drosophila melanogaster Abelson gene (abl), a gene in which recessive loss-of-function mutations result in lethality at the pupal stage of development. This essential gene consists of 10 exons extending over 26 kilobase pairs of genomic DNA. The DNA sequence encodes a protein of 1,520 amino acids with strong sequence similarity to the human c-abl proto-oncogene beginning in the type lb 5' exon and extending through the region essential for tyrosine kinase activity. When the tyrosine kinase homologous region was expressed in Escherichia coli, phosphorylation of proteins on tyrosine residues was observed with an antiphosphotyrosine antibody. These results show that the abl gene is highly conserved through evolution and encodes a functional tyrosine protein kinase required for Drosophila development.
Assuntos
Drosophila melanogaster/genética , Genes , Proteínas Tirosina Quinases/genética , Proto-Oncogenes , Sequência de Aminoácidos , Animais , Sequência de Bases , Enzimas de Restrição do DNA , Drosophila melanogaster/enzimologia , Genes Letais , Dados de Sequência Molecular , Mutação , Proto-Oncogene Mas , PupaRESUMO
The Abelson gene in Drosophila (abl) consists of ten exons extending over 26 kb of genomic DNA. The DNA sequence encodes a protein of 1520 amino acids with sequence homology to the human c-abl proto-oncogene product, beginning at the amino terminus and extending 656 amino acids through the region essential for tyrosine kinase activity. Mutant lesions in the abl gene were identified first by their failure to complement chromosomal deletions that overlap the abl DNA sequence and then by rescue of the mutant phenotypes with an abl minigene in transgenic flies. Elimination of abl zygotic function by mutations produces some recessive lethality at the pharate adult pupal stage, and mutant adults with reduced longevity, reduced fecundity, and an irregular pattern of retinal cells.