title: c-fos overexpression in splenic B cells augments development of marginal zone B cells.
abstract: Marginal zone (MZ)-B cells participate in very early immune responses and play a pivotal role in the first-line of defense against blood-borne Ags including bacterial LPS. Since splenic B cells from c-fos transgenic (H2-c-fos) mice are hyper-sensitive to LPS stimulation, we examined LPS-sensitivity of MZ-B cells in the spleen of H2-c-fos mice. Here, we show that proliferation of MZ-B cells from H2-c-fos mice stimulated with LPS was larger than that from control mice. Proliferation and IgM production of the H2-c-fos MZ-B cells were also larger than those of splenic follicular (FO)-B cells from the H2-c-fos mice, suggesting that c-fos overexpression augments LPS-sensitivity of MZ-B cells more than that of FO-B cells. Furthermore, the number of MZ-B cells but not that of FO-B cells in the spleen of H2-c-fos mice was two- to three-fold larger than that in control littermates. The number of transitional type II (T2)-B cells in H2-c-fos mice was also larger than that of control littermates. However, the number of transitional type I (T1)-B cells in the spleen of H2-c-fos mice was not larger than that of control mice. Moreover, this c-fos effect on differentiation of MZ-B cells was intrinsic in B cells by the competitive repopulation assay with hematopoietic stem cells of H2-c-fos and control mice. These results suggest that c-fos overexpression in B cells augments differentiation and accumulation of MZ-B cells.
authors.affiliation: Department of Developmental Genetics (H2), Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Yamashita
authors.forename: Akemi
authors.initials: A
authors.lastname: Sakamoto
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ohkubo
authors.forename: Masafumi
authors.initials: M
authors.lastname: Arima
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hatano
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Kuroda
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tokuhisa
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D001483:Base Sequence; D002454:Cell Differentiation; D049109:Cell Proliferation; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics; D016762:Genes, fos; D066298:In Vitro Techniques; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D013154:Spleen / Q000166:cytology
chemical_list: D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D008070:Lipopolysaccharides; C499308:Rag2 protein, mouse; C064655:V(D)J recombination activating protein 2