RRC ID 1966
Author Aki D, Mashima R, Saeki K, Minoda Y, Yamauchi M, Yoshimura A.
Title Modulation of TLR signalling by the C-terminal Src kinase (Csk) in macrophages.
Journal Genes Cells
Abstract In macrophages and monocytes, lipopolysaccharide (LPS) triggers the production of pro-inflammatory cytokine through Toll-like receptor (TLR) 4. Although major TLR signalling pathways are mediated by serine or threonine kinases including IKK, TAK1, p38 and JNKs, a number of reports suggested that tyrosine phosphorylation of intracellular proteins is involved in LPS signalling. Here, we identified several tyrosine-phosphorylated proteins using mass spectrometric analysis in response to LPS stimulation. Among these proteins, we characterized C-terminal Src kinase (Csk), which negatively regulates Src-like kinases in RAW 264.7 cells using RNAi knockdown technology. Unexpectedly, LPS-induced CD40 activation and the secretion of pro-inflammatory cytokine such as IL-6 and TNF-alpha, was down-regulated in Csk knockdown cells. Furthermore, overall cellular tyrosine phosphorylation and TLR4-mediated activation of IkappaB-alpha, Erk and p38 but not of JNK, were also down-regulated in Csk knockdown cells. The protein expression levels of a tyrosine kinase, Fgr, were reduced in Csk knockdown cells, suggesting that Csk is a critical regulator of TLR4-mediated signalling by modifying the levels of Src-like kinases.
Volume 10(4)
Pages 357-68
Published 2005-4
DOI 10.1111/j.1365-2443.2005.00839.x
PMID 15773898
MeSH Animals CD40 Antigens / metabolism Cell Line Chromatography, Liquid DNA-Binding Proteins / metabolism Down-Regulation Interleukin-6 / biosynthesis Lipopolysaccharides / pharmacology Macrophages / metabolism* Mass Spectrometry Mice Phosphorylation Protein-Tyrosine Kinases / genetics Protein-Tyrosine Kinases / metabolism* Receptors, Immunologic / metabolism Receptors, Immunologic / physiology* STAT1 Transcription Factor STAT3 Transcription Factor Signal Transduction* Toll-Like Receptor 4 Trans-Activators / metabolism Tumor Necrosis Factor-alpha / metabolism Tyrosine / metabolism* src-Family Kinases
IF 2.048
Times Cited 27
Human and Animal Cells RAW 264