A spontaneous internal deletion of the c-myb protooncogene enhances transcriptional activation in bovine T lymphoma cells.
Three double negative (BoCD4-, BoCD8-) bovine T cell lines, BTL-PC3, BLT2, and Pr2181, which have been established from bovine lymphosarcomas, were examined for expression and molecular function of bovine c-myb genes. BTL-PC3 expressed 4.0- and 3.6-kilobase c-myb transcripts, and BLT2 and Pr2181 expressed a 3.8-kilobase c-myb message. The c-Myb protein (75 kDa) was detected in Pr2181 but not as a clear band in BLT2, while BTL-PC3 exhibited a 65-kDa c-Myb band in immunoprecipitation tests with anti-Myb antiserum. Nucleotide sequences for c-myb cDNA clones from BTL-PC3 and BLT2 indicated that the predicted bovine wild-type c-Myb from BLT2 consists of 640 amino acids whereas that from BTL-PC3 consists of 555 amino acids lacking 85 internal amino acids. This deleted DNA region (255 base pairs consisting of 85 amino acids) corresponds to the human genomic exon 9 encoding a negative regulatory domain in the c-myb gene. Upon cotransfections with reporter plasmids containing myb binding sites, the internally deleted c-Myb exhibited a 3-fold higher transcriptional activity than the wild-type c-Myb in chloramphenicol acetyltransferase assays. These results indicate that internal DNA deletion in the c-myb gene is directly involved in the enhancement of transcriptional activation in bovine T lymphoma cells.
Ishiguro
N
N
Department of Veterinary Public Health, Obihiro University of Agriculture and Veterinary Medicine, Japan.
Ohzono
T
T
Shinagawa
T
T
Horiuchi
M
M
Shinagawa
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002418:Cattle Diseases / Q000235:genetics*; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D005091:Exons / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D008228:Lymphoma, Non-Hodgkin / Q000209:etiology / Q000662:veterinary; D016399:Lymphoma, T-Cell / Q000662:veterinary*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016133:Polymerase Chain Reaction; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D020598:Proto-Oncogene Proteins c-myb; D011519:Proto-Oncogenes / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured
D018076:DNA, Complementary; D011518:Proto-Oncogene Proteins; D020598:Proto-Oncogene Proteins c-myb; D011993:Recombinant Fusion Proteins; D015500:Chloramphenicol O-Acetyltransferase