title: Combinational recognition of bacterial lipoproteins and peptidoglycan by chicken Toll-like receptor 2 subfamily.
abstract: Human Toll-like receptor 2 (TLR2) subfamily recognizes bacterial lipoproteins (BLP) and peptidoglycan (PGN). According to the genome information, chicken has structural orthologs of TLRs1 and 2, in addition to TLRs3, 4, 5 and 7. Chicken has two additional TLRs, TLR15 and TLR21, whose orthologs human lacks. The chicken (ch)TLR1 and 2 genes are individually duplicated to encode for four different proteins, chTLR1-1, 1-2, 2-1 and 2-2, of the TLR2 subfamily. Here we investigated the functional profile of these TLR2 subfamily proteins of chicken. By NF-kappaB reporter assay using HEK293 cells, we found that chTLR2-1 and chTLR1-2 cooperatively signal the presence of PGN. A combination of chTLR2-1 and chTLR1-2 also most efficiently recognized diacylated BLP, macrophage-activating lipopeptide 2kDa (Malp-2), while the combination of chTLR2-1 and chTLR1-1 failed to recognize Malp-2. All combinations, however, recognized triacylated BLP, Pam3. Consistent with these results, human TLR2-stimulating mycobacteria preparations, BCG-cell wall and cell lysate of Mycobacterium avium, induced activation of NF-kappaB in cells expressing chTLR2-1 and 1-2 and to lesser extents, cells with chTLR2-2 and either of chTLR1. Strikingly, expression of either of these alone did not activate the reporter for NF-kappaB. These chTLRs are likely to have the combination functional feature as in the human TLR2 subfamily. Confocal and immunoprecipitation analyses of human cell transfectants showed that they cluster on the cell surface by a physical molecular association, causing all of them to merge and coprecipitate. These results suggest that chTLR2 subfamily members discriminate between their ligands by combinational events.
authors.affiliation: Department of Microbiology and Immunology, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo 060-8638, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Higuchi
authors.forename: Aya
authors.initials: A
authors.lastname: Matsuo
authors.forename: Masashi
authors.initials: M
authors.lastname: Shingai
authors.forename: Kyoko
authors.initials: K
authors.lastname: Shida
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ishii
authors.forename: Kenji
authors.initials: K
authors.lastname: Funami
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Oshiumi
authors.forename: Misako
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Seya
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D002645:Chickens; D006801:Humans; D008074:Lipoproteins / Q000276:immunology* / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010457:Peptidoglycan / Q000276:immunology* / Q000378:metabolism; D010802:Phylogeny; D015398:Signal Transduction; D051195:Toll-Like Receptor 2 / Q000276:immunology* / Q000378:metabolism; D051193:Toll-Like Receptors / Q000276:immunology / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D008074:Lipoproteins; D016328:NF-kappa B; D010457:Peptidoglycan; D051195:Toll-Like Receptor 2; D051193:Toll-Like Receptors