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

Hitoshi Katsuta, Sachiyo Tsuji, Yoshiyuki Niho, Tomohiro Kurosaki, Daisuke Kitamura

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

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-γ2 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.

Original languageEnglish
Pages (from-to)1547-1551
Number of pages5
JournalJournal of Immunology
Volume160
Issue number4
Publication statusPublished - Feb 15 1998

All Science Journal Classification (ASJC) codes

  • Immunology and Allergy
  • Immunology

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