Possible stage-specific function of NF-kappaB during pre-B cell differentiation.
Lipopolysaccharide (LPS)-induced differentiation of the murine pre-B cell line 70Z/3 is a model for pre-B to B cell differentiation and has been used to show that the transcription factor NF-kappaB is essential to induce the expression of the Ig kappa gene. We have investigated the mechanism involved in late stages of the process when all cells have reached a more mature B phenotype, i.e. beyond 48 up to 96 h of LPS treatment. NF-kappaB binding activity was induced at early times by LPS treatment, but its DNA binding activity disappeared after 84 h of LPS treatment. Accumulation of IkappaB alpha protein in the nucleus correlated with the disappearance of NF-kappaB activity at 72, 84 and 96 h, and treatment of nuclear extracts of 72-96 h LPS-treated cells with Na-deoxycholate restored NF-kappaB binding activity. The data indicate that NF-kappaB, while important to initiate the process of Ig kappa gene transcription in 70Z/3 pre-B cells, is no longer required for its maintenance in differentiated 70Z/3 cells.
Guerrini
L
L
Department of Genetics and Microbial Biology, University of Milan, Italy. guerrini@imiucca.csi.unimi.it
Molteni
A
A
Blasi
F
F
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology* / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D018507:Gene Expression Regulation, Developmental; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D016328:NF-kappa B / Q000502:physiology*
D008070:Lipopolysaccharides; D016328:NF-kappa B