PKCbeta modulates antigen receptor signaling via regulation of Btk membrane localization.
Article Details
- CitationCopy to clipboard
Kang SW, Wahl MI, Chu J, Kitaura J, Kawakami Y, Kato RM, Tabuchi R, Tarakhovsky A, Kawakami T, Turck CW, Witte ON, Rawlings DJ
PKCbeta modulates antigen receptor signaling via regulation of Btk membrane localization.
EMBO J. 2001 Oct 15;20(20):5692-702.
- PubMed ID
- 11598012 [ View in PubMed]
- Abstract
Mutations in Bruton's tyrosine kinase (Btk) result in X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (xid) in mice. While targeted disruption of the protein kinase C-beta (PKCbeta) gene in mice results in an immunodeficiency similar to xid, the overall tyrosine phosphorylation of Btk is significantly enhanced in PKCbeta-deficient B cells. We provide direct evidence that PKCbeta acts as a feedback loop inhibitor of Btk activation. Inhibition of PKCbeta results in a dramatic increase in B-cell receptor (BCR)-mediated Ca2+ signaling. We identified a highly conserved PKCbeta serine phosphorylation site in a short linker within the Tec homology domain of Btk. Mutation of this phosphorylation site led to enhanced tyrosine phosphorylation and membrane association of Btk, and augmented BCR and FcepsilonRI-mediated signaling in B and mast cells, respectively. These findings provide a novel mechanism whereby reversible translocation of Btk/Tec kinases regulates the threshold for immunoreceptor signaling and thereby modulates lymphocyte activation.