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Generation of phosphatidic acid and diacylglycerols following ligation of surface immunoglobulin in human B lymphocytes: potential role in PKC activation.

Abstract：

:We have examined signal transduction via membrane IgM (mIgM) in resting and cycling human B cells. Crosslinking mIgM on all of the cell types studied transduced a signal through the phosphatidylinositol pathway, producing inositol 1,4,5-trisphosphate and release of intracellular free calcium. These second messengers were formed regardless of quantitative or qualitative differences in the surface expression of mIgM: cells that had low levels of surface IgM (T-51) or had no light chain associated with surface heavy chain (DB) signaled phosphatidylinositol pathway activation after mIgM crosslinking. Production of specific lipid products in nonquiescent B cells differed from that in normal resting cells. Ligation of surface immunoglobulin on resting B cells resulted in sustained increases of both diacylglycerol and phosphatidic acid, two lipids that can influence PKC activation. Whereas PKC was strongly activated in normal tonsillar B cells, several cell lines had reduced PKC activation following crosslinking of mIgM. The reduction in protein kinase C activation correlated with the absence or reduced levels of phosphatidic acid or diacylglycerol following stimulation: protein kinase C translocated and was activated only in cells that had elevated levels of both diacylglycerides and phosphatidic acid. Anti-IgM-induced phosphorylation of a protein kinase C substrate protein CD20, also increased in those cells having PKC activation and not in cells in which kinase activity was reduced. CD20 phosphorylation also increased following the direct addition of exogenous phosphatidic acid to resting B cells. Together, these observations show that the generation of lipid products following mIgM crosslinking in resting cells can vary from that in cycling cells and may relate to the different levels of PKC activation. In a companion study we report that ligation of surface IgM activates both an acyltransferase and phospholipase D to form phosphatidic acid.

journal_name

Cell Immunol

journal_title

Cellular immunology

authors

Valentine MA,Bursten SL,Harris WE,Draves KE,Pollok BA,Ostrowski J,Bomsztyk K,Clark EA

doi

10.1016/0008-8749(92)90156-j

subject

Has Abstract

pub_date

1992-05-01 00:00:00

pages

373-87

issue

eissn

0008-8749

issn

1090-2163

pii

0008-8749(92)90156-J

journal_volume

141

pub_type

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Generation of phosphatidic acid and diacylglycerols following ligation of surface immunoglobulin in human B lymphocytes: potential role in PKC activation.