title: Induction of CD45 isoform switch in murine B cells by antigen receptor stimulation and by phorbol myristate acetate and ionomycin.
abstract: In this study, we examined whether CD45 isoform can be switched in murine mature B cells and what signals are responsible for the process. Stimulation of murine splenic B cells with lipopolysaccharide did not reduce the expression of CD45RA-, B-, and C-exon-dependent epitopes or a CD45 common epitope, but rather enhanced the expression. Stimulation with goat antimouse IgM antibody did not significantly reduce CD45 expression but caused a partial reduction in the expression of CD45RA-, B-, and C-exon-dependent epitopes. Phorbol myristate acetate (PMA) alone did not significantly alter the expression of CD45 but the combination of PMA and ionomycin induced a strong reduction in the expression of CD45RA-, B-, and C-exon-dependent epitopes without affecting the level of CD45 common epitope expression. Reverse transcription and polymerase chain reaction analysis demonstrated that CD45 isoform switch induced by anti-IgM or PMA plus ionomycin is indeed mediated by alternative splicing of A-, B-, and C-exon-derived mRNA. These results suggest that CD45 isoform of murine mature B cells can be switched by antigen receptor-mediated signals, and the process seems to be regulated at least in part by protein kinase C activation and mobilization of calcium ions.
authors.affiliation: Tokyo Metropolitan Institute for Neuroscience, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Ogimoto
authors.forename: T
authors.initials: T
authors.lastname: Katagiri
authors.forename: K
authors.initials: K
authors.lastname: Hasegawa
authors.forename: K
authors.initials: K
authors.lastname: Mizuno
authors.forename: H
authors.initials: H
authors.lastname: Yakura
mesh_terms: D017398:Alternative Splicing / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000494:pharmacology; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D001483:Base Sequence; D007075:Immunoglobulin M / Q000276:immunology; D015759:Ionomycin / Q000494:pharmacology; D017493:Leukocyte Common Antigens / Q000097:blood / Q000235:genetics*; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008969:Molecular Sequence Data; D011947:Receptors, Antigen, B-Cell / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D000888:Antibodies, Anti-Idiotypic; D007075:Immunoglobulin M; D008070:Lipopolysaccharides; D011947:Receptors, Antigen, B-Cell; D015759:Ionomycin; D017493:Leukocyte Common Antigens; D013755:Tetradecanoylphorbol Acetate