The regulated expression of B lineage associated genes during B cell differentiation in bone marrow and fetal liver.
The expression of B lineage associated genes during early B cell differentiation stages is not firmly established. Using cell surface markers and multiparameter flow cytometry, bone marrow (BM) cells can be resolved into six fractions, representing sequential stages of development; i.e., pre-Pro-B, early Pro-B, late Pro-B/large Pre-B, small Pre-B, immature B, and mature B cells. Here we quantitate the levels of several B lineage associated genes in each of these fractions by RT-PCR, demonstrating different patterns of expression. We find that expression of terminal deoxynucleotidyl transferase (TdT), lambda 5, and VpreB is predominantly restricted to the Pro-B stages. Rag-1 and Rag-2 expression is also tightly regulated, and is found largely in the Pro-B through small Pre-B stages. Mb-1 is present from Pro-B throughout the pathway at high levels. Finally, Bcl-2 is expressed at high levels only at the pre-Pro-B and mature B stages, whereas it is low during all the intermediate stages. We also correlate this expression data with an analysis of the onset of Ig gene rearrangement as assessed by amplifying D-JH, VH-DJH, and VK-JK. Finally, we report differences in gene expression during B lymphopoiesis at two distinct ontogenic timings, in fetal liver and adult BM: both TdT and the precursor lymphocyte regulated myosin-like light chain are expressed at high levels in the Pro-B cell stage in bone marrow, but are absent from the corresponding fraction in fetal liver. In contrast, lambda 5, VpreB, Rag-1, and Rag-2 are expressed at comparable levels.
Li
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Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111.
Hayakawa
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Hardy
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D000818:Animals; D015703:Antigens, CD; D001402:B-Lymphocytes / Q000166:cytology* / Q000502:physiology; D001483:Base Sequence; D001854:Bone Marrow Cells; D051925:CD79 Antigens; D002454:Cell Differentiation; D004253:DNA Nucleotidylexotransferase / Q000235:genetics; D004268:DNA-Binding Proteins; D005260:Female; D005786:Gene Expression Regulation; D015322:Gene Rearrangement, B-Lymphocyte; D005803:Genes, Immunoglobulin; D006410:Hematopoiesis; D018398:Homeodomain Proteins; D008099:Liver / Q000196:embryology*; D008562:Membrane Glycoproteins / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D011506:Proteins / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger / Q000235:genetics; D011947:Receptors, Antigen, B-Cell / Q000235:genetics
D015703:Antigens, CD; D051925:CD79 Antigens; C497882:Cd79a protein, mouse; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D008562:Membrane Glycoproteins; D009838:Oligodeoxyribonucleotides; D011506:Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; C499308:Rag2 protein, mouse; D011947:Receptors, Antigen, B-Cell; C064655:V(D)J recombination activating protein 2; C064658:RAG-1 protein; D004253:DNA Nucleotidylexotransferase