Oxidant-Dependent Phosphorylation of p40phox in B Lymphocytes

Author： Grandvaux N. Elsen S. Vignais P.V.

Publisher： Elsevier

ISSN： 0006-291X

Source： Biochemical and Biophysical Research Communications, Vol.287, Iss.4, 2001-10, pp. : 1009-1016

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

As with the neutrophil NADPH oxidase, the B lymphocyte NADPH oxidase consists of a membrane-bound flavocytochrome b and regulatory factors including Rac and the cytosolic phox protein triad p67phox, p47phox, and p40phox. Here we demonstrate by phosphoamino acid analysis and the use of the potent PKC inhibitor GFX that, in response to stimulation of B lymphocytes with sodium orthovanadate and H₂O₂, the p40phox component of the cytosolic phox triad is selectively phosphorylated on serine and threonine residues by a PKC-type protein kinase. The pattern of p40phox phosphorylation was closely related to the kinetics of tyrosine phosphorylation of PKC-δ, the main PKC isotype of B lymphocytes. Blocking H₂O₂-dependent tyrosine phosphorylation of PKC by genistein resulted in inhibition of p40phox phosphorylation. The correlation between the tyrosine phosphorylation of PKC-δ and the serine/threonine phosphorylation of p40phox, together with the inhibition of p40phox phosphorylation by rottlerin, a selective inhibitor of PKC-δ, makes the activated PKC-δ a likely candidate in the process of the oxidant-dependent phosphorylation of p40phox in B cells.