Lyn-mediated down-regulation of B cell antigen receptor signaling: inhibition of protein kinase C activation by Lyn in a kinase-independent fashion - PubMed (original) (raw)

. 1998 Feb 15;160(4):1547-51.

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Lyn-mediated down-regulation of B cell antigen receptor signaling: inhibition of protein kinase C activation by Lyn in a kinase-independent fashion

H Katsuta et al. J Immunol. 1998.

Abstract

Stimulation of the B cell Ag receptor (BCR) induces activation of tyrosine kinases such as Lyn and Syk, phosphorylation and activation of multiple signaling components, and eventually, the expression of several genes including c-myc. Syk is required for activation of phospholipase C-gamma 2 and the subsequent phosphatidylinositol hydrolysis, leading to protein kinase C (PKC) activation and intracellular Ca2+ increase. In contrast, the function of Lyn remains obscure. Here, we report that BCR-mediated induction of c-myc promoter activity and of PKC activity, but not the expression level of functional PKC, was markedly augmented in Lyn-deficient chicken B cells. This enhancement was reversed to the level of wild-type cells by the expression of exogenous Lyn of kinase-inactive form. These results indicate that Lyn inhibits BCR-mediated activation of a large portion of PKC isozymes in a kinase-independent fashion. This finding reveals a novel role of Lyn in negative regulation of BCR signaling.

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