Regulation of promoter and intron enhancer activity in immunoglobulin heavy-chain genes during B-cell differentiation.
Chloramphenicol acetyltransferase (CAT) transgenic mice, in which the transgene is regulated by the VH promoter and heavy-chain intron enhancer (E mu), were examined to investigate the variation of activity of these cis-acting elements during the late stage of B-cell development. CAT enzyme activity decreased when resting B cells were stimulated through B-cell receptors (BCR) with goat anti-mouse IgM antibodies in vitro. On the other hand, when these B cells were stimulated by lipopolysaccharide (LPS) in vitro, they showed enhanced CAT activity, accompanied by an increase in the number of CD43+ B220+ cells (pro-plasma and plasma cells). In addition, the CAT activities in CD43+ B220+ and PNAhi B220+ cells from immunized mice were higher than those in CD43- B220+ and PNAlo B220+ cells, respectively. These results suggest that the activity of E mu in the context of VH promoter was transiently down-regulated by stimulation through the BCR but enhanced at the pro-plasma and plasma stages.
Naito
A
A
Division of Molecular Immunology, Research Institute for Biological Sciences, Science University of Tokyo, Chiba, Japan.
Suzuki
Y
Y
Azuma
T
T
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects; D002452:Cell Count; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics*; D002478:Cells, Cultured; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D005803:Genes, Immunoglobulin / Q000235:genetics*; D007075:Immunoglobulin M / Q000494:pharmacology; D007438:Introns / Q000235:genetics*; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D008822:Mice, Transgenic; D010950:Plasma Cells / Q000276:immunology; D013154:Spleen
D007075:Immunoglobulin M; D008070:Lipopolysaccharides; D015500:Chloramphenicol O-Acetyltransferase