Mycobacterium tuberculosis lipoprotein-induced association of TLR2 with protein kinase C zeta in lipid rafts contributes to reactive oxygen species-dependent inflammatory signalling in macrophages

Cell Microbiol. 2008 Sep;10(9):1893-905. doi: 10.1111/j.1462-5822.2008.01179.x. Epub 2008 Jul 15.

Abstract

Membrane lipid rafts are enriched in cholesterol and play an important role as signalling platforms. However, the roles of lipid rafts and associated signalling molecules in the innate immune responses to mycobacteria remain unknown. Here we show that stimulation with Mycobacterium tuberculosis 19 kDa lipoprotein, a TLR2/1 agonist, results in translocation of TLR2 to lipid rafts, coalescence of lipid rafts and production of reactive oxygen species (ROS) that drive pro-inflammatory responses. Disruption of lipid raft organization markedly reduced lipoprotein-induced ROS and inflammatory responses. Remarkably, the atypical protein kinase C (PKC) zeta was specifically recruited into detergent-resistant membrane fractions and associated with TLR2. PKCzeta activity was critical for lipoprotein-dependent ROS generation, raft coalescence and the pro-inflammatory responses by macrophages. Moreover, lipid raft organization was required for 19 kDa mediated PKCzeta activation. These results demonstrate that TLR2 trafficking and raft coalescence play an essential role for the initiation of lipoprotein-induced innate immune responses via TLR2 and ROS signalling. In addition, PKCzeta targets to lipid rafts and may act as a critical adaptor molecule to regulate lipid raft dynamics during TLR2 signalling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Proteins / immunology*
  • Bacterial Proteins / pharmacology
  • Cells, Cultured
  • Cytokines / immunology
  • Immunity, Innate
  • Inflammation / immunology
  • Lipoproteins / immunology*
  • Lipoproteins / pharmacology
  • Macrophage Activation
  • Macrophages / immunology
  • Macrophages / metabolism
  • Membrane Microdomains / drug effects
  • Membrane Microdomains / immunology*
  • Mice
  • Mice, Inbred C3H
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mycobacterium tuberculosis / immunology*
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / metabolism*
  • Protein Transport
  • Reactive Oxygen Species / metabolism
  • Signal Transduction
  • Toll-Like Receptor 2 / agonists
  • Toll-Like Receptor 2 / metabolism*
  • Tuberculosis / immunology*
  • Tuberculosis / metabolism
  • beta-Cyclodextrins / pharmacology

Substances

  • 19 kDa antigen, Mycobacterium
  • Bacterial Proteins
  • Cytokines
  • Lipoproteins
  • Reactive Oxygen Species
  • Toll-Like Receptor 2
  • beta-Cyclodextrins
  • methyl-beta-cyclodextrin
  • protein kinase C zeta
  • Protein Kinase C