title: Hematopoietic lineage-specific heterogeneity in the 5'-terminal region of the chicken proto-myb transcript.
abstract: Comparison of the nucleotide sequence of the upstream c-myb exon UE3 with the sequences of a thymus c-myb cDNA and of a B-lymphoma c-myb cDNA suggested the existence of T- and B-cell-specific heterogeneity in the 5'-terminal region of the c-myb coding sequence. This possibility was investigated with T-cell-specific and B-cell-specific DNA probes in a Northern (RNA) blot analysis of mRNAs from different hematopoietic cell types and from chicken embryo fibroblasts. The hematopoietic tissues analyzed were bone marrow, bursa of Fabricius, and thymus from 1-day-old chicks, 13-day yolk sac, and spleen from 16-day embryos. At least three different c-myb mRNA species were found to have 5'-terminal heterogeneity that was specific for either B cells, T cells, or the other hematopoietic cells and chicken embryo fibroblasts. This lineage-specific heterogeneity in the c-myb transcript was found to be expressed in the bone marrow precursors of B and T cells before they migrated to their definitive differentiation sites. S1 nuclease protection analysis of the UE3 exon, part of which appeared to be coding sequences for thymic c-myb mRNA, revealed that this exon is utilized either in its entirety or partially in a cell-lineage-specific manner by all six tissues analyzed. Also, the 5'-terminal exon(s) present in the thymus cDNA was absent in c-myb mRNAs from the other cell types analyzed.
authors.affiliation: Department of Pathology, School of Medicine, University of California, Los Angeles 90024.
authors.forename: W K
authors.initials: WK
authors.lastname: Kim
authors.forename: M A
authors.initials: MA
authors.lastname: Baluda
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism; D004247:DNA / Q000235:genetics; D015342:DNA Probes; D004720:Endonucleases; D005091:Exons; D006413:Hematopoietic System / Q000166:cytology / Q000378:metabolism*; D011519:Proto-Oncogenes; D012333:RNA, Messenger / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D015719:Single-Strand Specific DNA and RNA Endonucleases; D013601:T-Lymphocytes / Q000378:metabolism; D014018:Tissue Distribution; D014158:Transcription, Genetic
chemical_list: D015342:DNA Probes; D012333:RNA, Messenger; D004247:DNA; D004720:Endonucleases; D015719:Single-Strand Specific DNA and RNA Endonucleases