Cellular, intracellular, and developmental expression patterns of murine SWAP-70.
SWAP-70 is part of a protein complex that catalyzes cell-free DNA recombination between immunoglobulin heavy chain gene switch region substrates. This report studies the expression pattern of SWAP-70 in mouse tissues, sorted cells, and cultured primary cells. SWAP-70 RNA is strongly increased upon switch-induction of spleen cells, and very weakly expressed in thymus and bone marrow. SWAP-70 protein is specifically expressed in B cells, and levels increase rapidly after stimulation. Tissue staining shows strong expression in germinal center B cells, while macrophages and T lymphocytes do not stain. SWAP-70 is not detected in early B cells in the bone marrow. Its expression during mouse ontogeny after birth correlates with the appearance of non-IgM isotypes. While SWAP-70 localizes to the cell nucleus in activated B cells, it is not tightly associated with the chromatin and is found in the cytoplasm as well. SWAP-70 expression is not increased by gamma or UV irradiation of spleen cells, nor does it depend on p53. These characteristics are consistent with the putative role of SWAP-70 in immunoglobulin class switching.
Borggrefe
T
T
Basel Institute for Immunology, Switzerland.
Masat
L
L
Wabl
M
M
Riwar
B
B
Cattoretti
G
G
Jessberger
R
R
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000528:radiation effects; D020662:Guanine Nucleotide Exchange Factors; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D015778:Minor Histocompatibility Antigens; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics*; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D013347:Subcellular Fractions / Q000378:metabolism; D014018:Tissue Distribution
D004268:DNA-Binding Proteins; D020662:Guanine Nucleotide Exchange Factors; D015778:Minor Histocompatibility Antigens; D009687:Nuclear Proteins; D012333:RNA, Messenger; C113365:Swap70 protein, mouse