Btk regulation in human and mouse B cells via protein kinase C phosphorylation of IBtkγ.
Blood
; 117(24): 6520-31, 2011 Jun 16.
Article
em En
| MEDLINE
| ID: mdl-21482705
ABSTRACT
The inhibitor of Bruton tyrosine kinase γ (IBtkγ) is a negative regulator of the Bruton tyrosine kinase (Btk), which plays a major role in B-cell differentiation; however, the mechanisms of IBtkγ-mediated regulation of Btk are unknown. Here we report that B-cell receptor (BCR) triggering caused serine-phosphorylation of IBtkγ at protein kinase C consensus sites and dissociation from Btk. By liquid chromatography and mass-mass spectrometry and functional analysis, we identified IBtkγ-S87 and -S90 as the critical amino acid residues that regulate the IBtkγ binding affinity to Btk. Consistently, the mutants IBtkγ carrying S87A and S90A mutations bound constitutively to Btk and down-regulated Ca(2+) fluxes and NF-κB activation on BCR triggering. Accordingly, spleen B cells from Ibtkγ(-/-) mice showed an increased activation of Btk, as evaluated by Y551-phosphorylation and sustained Ca(2+) mobilization on BCR engagement. These findings identify a novel pathway of Btk regulation via protein kinase C phosphorylation of IBtkγ.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Proteína Quinase C
/
Proteínas Tirosina Quinases
/
Proteínas de Transporte
/
Células
Tipo de estudo:
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Ano de publicação:
2011
Tipo de documento:
Article