Limited expression of C/EBP family proteins during B lymphocyte development. Negative regulator Ig/EBP predominates early and activator NF-IL-6 is induced later.
The importance of C/EBP proteins in B cell biology is suggested by the occurrence of functionally important C/EBP binding sites in Ig gene enhancers and promoters, and the knowledge that family member NF-IL-6 is induced in other systems in response to regulators of B cell differentiation. We have studied the expression pattern and activity of C/EBP family transcriptional regulators in B cells at different developmental stages by using B cell lines and normal splenic B cells. Two family members, Ig/EBP and NF-IL-6, seem to be the major regulators of C/EBP site-dependent transcriptional activity in B cells. Negative regulator Ig/EBP is predominantly present in early B cells; activator NF-IL-6 increases in more mature B cells and is induced by LPS activation of splenic B cells. LIP, an N-terminally truncated form of NF-IL-6, was found in most B cell lines tested; LIP can act as a weak transcriptional activator in B cell lines. Partly as a result of the differential amounts of C/EBP family proteins, C/EBP sites do not function as activator sites in early B cells but are activator sites in terminally differentiated B cells.
Department of Microbiology, College of Physician and Surgeons, Columbia University, New York, NY 10032.
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CL
Cooper
A L
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Berrier
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C
Roman
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Calame
D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D015153:Blotting, Western; D022762:CCAAT-Enhancer-Binding Proteins; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D015536:Down-Regulation / Q000276:immunology; D005260:Female; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000276:immunology; D051379:Mice; D008815:Mice, Inbred Strains; D009687:Nuclear Proteins / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000096:biosynthesis; D013154:Spleen / Q000166:cytology; D014157:Transcription Factors / Q000096:biosynthesis*; D014162:Transfection / Q000235:genetics; D015854:Up-Regulation / Q000276:immunology
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D007143:Immunoglobulin Heavy Chains; D008070:Lipopolysaccharides; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors