title: CD300F blocks both MyD88 and TRIF-mediated TLR signaling through activation of Src homology region 2 domain-containing phosphatase 1.
abstract: CD300F is known to exhibit inhibitory activity in myeloid cells through its intracellular ITIM. To investigate the effect of CD300F stimulation on TLR signaling, the human acute monocytic leukemia cell line THP-1 was treated with CD300F-specific mAbs or two synthetic peptides that represented the ITIM-like domains of CD300F. Treatment with these agents blocked TLR2-, 3-, 4-, and 9-mediated expression of proinflammatory mediators such as IL-8 and matrix metalloproteinase-9. The luciferase reporter assay in 293T cells and Western blot analysis of THP-1 cells revealed that these inhibitory actions were effective in pathways involving MyD88 and/or TRIF of TLR signaling and associated with marked suppression of IκB kinase activation, phosphorylation/degradation of IκB, and subsequent activation of NF-κB. Use of specific inhibitors and immunoprecipitation analysis further indicated that the inhibitory effects were mediated by Src homology 2 domain-containing phosphatase-1, a protein tyrosine phosphatase with inhibitory activity in hematopoietic cells. These data indicate that CD300F is an active regulator of TLR-mediated macrophage activation through its association with Src homology 2 domain-containing phosphatase-1 and that the synthetic peptides can be applied for the regulation of immune responses that are induced by TLRs.
authors.affiliation: School of Life Sciences and Biotechnology, Kyungpook National University, Daegu 702-701, Korea.
authors.forename: Sang-Min
authors.initials: SM
authors.lastname: Lee
authors.forename: Eun-Ju
authors.initials: EJ
authors.lastname: Kim
authors.forename: Kyoungho
authors.initials: K
authors.lastname: Suk
authors.forename: Won-Ha
authors.initials: WH
authors.lastname: Lee
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism*; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D015153:Blotting, Western; D045744:Cell Line, Tumor; D057809:HEK293 Cells; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6 / Q000276:immunology / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D051196:Toll-Like Receptor 3 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D051217:Toll-Like Receptor 9 / Q000378:metabolism; D051193:Toll-Like Receptors / Q000378:metabolism*; D020298:U937 Cells
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D000911:Antibodies, Monoclonal; C519443:CD300LF protein, human; D016209:Interleukin-8; C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D010455:Peptides; D011971:Receptors, Immunologic; C470409:TICAM1 protein, human; C495342:TLR2 protein, human; C495344:TLR3 protein, human; C495345:TLR4 protein, human; C495371:TLR9 protein, human; D051195:Toll-Like Receptor 2; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D051217:Toll-Like Receptor 9; D051193:Toll-Like Receptors; D051550:I-kappa B Kinase; C509249:PTPN6 protein, human; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6