title: The Fps/Fes kinase regulates the inflammatory response to endotoxin through down-regulation of TLR4, NF-kappaB activation, and TNF-alpha secretion in macrophages.
abstract: Fps/Fes and Fer are members of a distinct subfamily of cytoplasmic protein tyrosine kinases that have recently been implicated in the regulation of innate immunity. Previous studies showed that mice lacking Fps/Fes are hypersensitive to systemic LPS challenge, and Fer-deficient mice displayed enhanced recruitment of leukocytes in response to local LPS challenge. This study identifies physiological, cellular, and molecular defects that contribute to the hyperinflammatory phenotype in Fps/Fes null mice. Plasma TNF-alpha levels were elevated in LPS challenged Fps/Fes null mice as compared with wild-type mice and cultured Fps/Fes null peritoneal macrophages treated with LPS showed increased TNF-alpha production. Cultured Fps/Fes null macrophages also displayed prolonged LPS-induced degradation of IkappaB-alpha, increased phosphorylation of the p65 subunit of NF-kappaB, and defective TLR4 internalization, compared with wild-type macrophages. Together, these observations provide a likely mechanistic basis for elevated proinflammatory cytokine secretion by Fps/Fes null macrophages and the increased sensitivity of Fps/Fes null mice to endotoxin. We posit that Fps/Fes modulates the innate immune response of macrophages to LPS, in part, by regulating internalization and down-regulation of the TLR4 receptor complex.
authors.affiliation: Division of Cancer Biology and Genetics, Botterell Hall, Room A309, Queens University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Sean A
authors.initials: SA
authors.lastname: Parsons
authors.forename: Peter A
authors.initials: PA
authors.lastname: Greer
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects / Q000276:immunology*; D020672:I-kappa B Proteins / Q000276:immunology / Q000378:metabolism; D007113:Immunity, Innate / Q000187:drug effects; D007249:Inflammation / Q000276:immunology / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology / Q000494:pharmacology*; D008262:Macrophage Activation; D017737:Macrophages, Peritoneal / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D000072000:NF-KappaB Inhibitor alpha; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000276:immunology; D051578:Proto-Oncogene Proteins c-fes / Q000172:deficiency / Q000276:immunology* / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000276:immunology*; D051996:Transcription Factor RelA / Q000276:immunology* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology* / Q000378:metabolism
chemical_list: D020672:I-kappa B Proteins; D008070:Lipopolysaccharides; C000606205:Nfkbia protein, mouse; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; C496646:Fes protein, mouse; D051578:Proto-Oncogene Proteins c-fes