Intracellular recognition of lipopolysaccharide by toll-like receptor 4 in intestinal epithelial cells.
Toll-like receptor (TLR)4 has recently been shown to reside in the Golgi apparatus of intestinal crypt epithelial m-ICcl2 cells, colocalizing with internalized lipopolysaccharide (LPS). Here we demonstrate that disruption of the integrity of the Golgi apparatus significantly reduced LPS-mediated nuclear factor kappaB activation. Also, the TLR4 adaptor protein MyD88 and the serine/threonine kinase IRAK-1 were rapidly recruited to the Golgi apparatus upon stimulation. LPS-mediated activation required lipid raft formation and intact clathrin-dependent internalization. In contrast to macrophages, prevention of ligand internalization by use of LPS-coated beads significantly impaired recognition by epithelial cells. The localization of TLR4 to the Golgi apparatus was abrogated by expression of a genetically modified form of the TLR4 binding chaperone gp96. Thus, our data provide evidence that in contrast to the situation in macrophages, LPS recognition in intestinal epithelial cells may occur in the Golgi apparatus and require LPS internalization.
Swedish Institute for Infectious Disease Control SMI, 17182 Solna, Sweden. mathias.hornef@smi.ki.se
Mathias W
MW
Hornef
Birgitta Henriques
BH
Normark
Alain
A
Vandewalle
Staffan
S
Normark
D000818:Animals; D002460:Cell Line; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000276:immunology; D006056:Golgi Apparatus / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000502:physiology; D007422:Intestines / Q000276:immunology*; D008070:Lipopolysaccharides / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000276:immunology*; D008565:Membrane Proteins / Q000502:physiology; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000276:immunology*; D015398:Signal Transduction; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors
D018840:HSP70 Heat-Shock Proteins; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D016328:NF-kappa B; D011956:Receptors, Cell Surface; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; C018551:glucose-regulated proteins