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Signal transduction through μκ B‐cell receptors expressed on pre‐B cells is different from that through B‐cell receptors on mature B cells
Author(s) -
NAKAMURA T.,
KOYAMA M.,
YONEYAMA A.,
HIGASHIHARA M.,
KAWAKAMI T.,
YAMAMURA H.,
SADA K.,
OKUMURA K.,
KUROKAWA K.
Publication year - 1996
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1046/j.1365-2567.1996.d01-681.x
Subject(s) - breakpoint cluster region , b cell receptor , signal transduction , b cell , biology , microbiology and biotechnology , receptor , cytoplasm , phosphatidylinositol , antibody , biochemistry , immunology
We introduced κ light chain genes into pre‐B cells to increase the surface μ HC expression, and established transfectants expressing mature type of B‐cell receptors (BCR) on pre‐B‐cell surfaces. Since the cytoplasmic conformations of the reconstituted BCR and intrinsic pre‐B‐cell receptor (pre‐BCR) are identical, they would be connected with the identical signal transduction pathways in pre‐B cells. By using the transfectants, we revealed that the reconstituted BCR on pre‐B cells was functionally equivalent to BCR on mature B cells in terms of the induction of intracellular Ca ++ mobilization. However, we found that the signal‐transduction pathways through BCR on pre‐B cells were quantitatively different from those of BCR on mature B cells in two ways. First, cross‐linkage of the reconstituted BCR on pre‐B cells induced preferential tyrosine phosphorylation of p120 and p100, which was not observed when BCR on mature B cells was cross‐linked. Second, BCR in pre‐B cells was physically associated with a larger amount of phosphatidylinositol‐3 kinase (PI‐3K) than BCR in mature B cells in spite of the fact that both pre‐B and B cells expressed a similar amount of PI‐3K in cytoplasm. Signals through pre‐BCR and BCR are known to cause distinct biological effects in B‐cell development. The biochemical features in the downstream of reconstituted BCR on pre‐B cells, which we revealed in this study, will be of help in understanding the mechanism of functional differences between pre‐BCR and BCR.