期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1991
卷号：88
期号：4
页码：1311-1314
DOI：10.1073/pnas.88.4.1311
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：It has been found that the principal biochemical pathway activated in B cells stimulated by antigen- or anti-immunoglobulin-mediated crosslinking of surface immunoglobulin is that resulting in hydrolysis of phosphatidylinositol bisphosphate with generation of diacylglycerol and inositol trisphosphate. Recent evidence suggests that surface immunoglobulin-mediated B-cell activation can proceed without detectable increases in the concentration of either diacylglycerol or intracellular Ca2+ concentration, implicating involvement of other non-protein-kinase-C/Ca2(+)-dependent signal-transduction pathways. Therefore, we sought evidence for activation of a signaling pathway that is associated with growth regulation in other cell types--i.e., the protein-tyrosine kinases. We now show that crosslinking of membrane immunoglobulin by mitogenic antibodies leads to rapid tyrosine phosphorylation of several cellular substrates, consistent with the induction of a tyrosine kinase activity. This increase in tyrosine phosphorylation is weakly (if at all) stimulated by other B-cell mitogens, including phorbol esters and ionophores, and does not require the presence of detectable protein kinase C. Furthermore, inhibition of anti-immunoglobulin-stimulated phosphatidylinositol bisphosphate hydrolysis does not inhibit activation of this tyrosine kinase-dependent pathway. These findings suggest that occupancy of the membrane immunoglobulin receptor may induce multiple pathways of activation.
