title: Pan/E2A expression precedes immunoglobulin heavy-chain expression during B lymphopoiesis in nontransformed cells, and Pan/E2A proteins are not detected in myeloid cells.
abstract: A newly developed rat long-term bone marrow culture system was used to study the role of Pan/E2A basic helix-loop-helix transcription factors during B-cell development. In this system, B-lymphocyte progenitors actively differentiate into mature B cells. Monoclonal (Yae) and polyclonal (anti-Pan) antibodies were employed to characterize the expression of Pan proteins by Western blot assay during hematopoiesis and to examine the components of immunoglobulin heavy-chain gene enhancer element-binding species by electrophoretic mobility shift assay. During B-cell development, the appearance of Pan/E2A proteins preceded the expression of immunoglobulin heavy-chain protein. A Pan-containing immunoglobulin heavy-chain enhancer element (mu E5)-binding species (BCF1), composed of immunoreactive Pan-1/E47 but not Pan-2/E12, was observed concomitantly with the detection of Pan/E2A proteins. In addition to BCF1, other mu E5-binding species were detected which were not recognized by the Yae antibody. Two of these species were present in primary B-lymphocyte and myeloid cultures and were recognized by an anti-upstream stimulatory factor antiserum. Although Pan/E2A proteins have been proposed to be ubiquitous, Pan/E2A proteins were not detected in primary myeloid cultures composed mainly of granulocytes and macrophages or in the macrophage cell line J774. The absence of Pan/E2A proteins in differentiated myeloid cells correlated with low steady-state levels of Pan/E2A RNA. However, Pan/E2A proteins were present in a promyeloid cell line, 32DCL3, suggesting that extinction of Pan/E2A expression may play a role in myelopoiesis.
authors.affiliation: Department of Biochemistry, University of California, Riverside 92521.
authors.forename: Y
authors.initials: Y
authors.lastname: Jacobs
authors.forename: X Q
authors.initials: XQ
authors.lastname: Xin
authors.forename: K
authors.initials: K
authors.lastname: Dorshkind
authors.forename: C
authors.initials: C
authors.lastname: Nelson
mesh_terms: D017502:Adenovirus E2 Proteins / Q000032:analysis / Q000096:biosynthesis*; D000818:Animals; D000906:Antibodies; D000911:Antibodies, Monoclonal; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D001483:Base Sequence; D015153:Blotting, Western; D001853:Bone Marrow / Q000378:metabolism; D001854:Bone Marrow Cells; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000032:analysis / Q000096:biosynthesis*; D004742:Enhancer Elements, Genetic; D015870:Gene Expression; D006412:Hematopoietic Stem Cells / Q000276:immunology / Q000378:metabolism*; D007143:Immunoglobulin Heavy Chains / Q000032:analysis / Q000096:biosynthesis*; D008264:Macrophages / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D014176:Protein Biosynthesis; D051381:Rats; D014157:Transcription Factors / Q000032:analysis / Q000096:biosynthesis*; D014158:Transcription, Genetic
chemical_list: D017502:Adenovirus E2 Proteins; D000906:Antibodies; D000911:Antibodies, Monoclonal; D004268:DNA-Binding Proteins; D007143:Immunoglobulin Heavy Chains; D015345:Oligonucleotide Probes; D014157:Transcription Factors