title: Gangliosides act as co-receptors for Salmonella enteritidis FliC and promote FliC induction of human beta-defensin-2 expression in Caco-2 cells.
abstract: Antimicrobial peptides such as defensins are crucial for host defense at mucosal surfaces. We reported previously that Salmonella enteritidis flagellin (FliC) induced human beta-defensin-2 (hBD-2) mRNA expression in Caco-2 cells via NF-kappaB activation (Ogushi, K., Wada, A., Niidome, T., Mori, N., Oishi, K., Nagatake, T., Takahashi, A., Asakura, H., Makino, S., Hojo, H., Nakahara, Y., Ohsaki, M., Hatakeyama, T., Aoyagi, H., Kurazono, H., Moss, J., and Hirayama, T. (2001) J. Biol. Chem. 276, 30521-30526). In this study, we examined the role of ganglioside as co-receptors with Toll-like receptor 5 (TLR5) on FliC induction of hBD-2 expression in Caco-2 cells. Exogenous gangliosides suppressed FliC induction of hBD-2 promoter activity and binding of FliC to Caco-2 cells. Incorporation of exogenous ganglioside GD1a into Caco-2 cell membranes increased the effect of FliC on hBD-2 promoter activity. In support of a role for endogenous gangliosides, incubation of Caco-2 cells with dl-threo-2-hexadecanoylamino-3-morpholino-1-phenylpropanol, a glucosylceramide synthase inhibitor, reduced FliC induction of hBD-2 promoter activity. GD1a-loaded CHO-K1-expressing TLR5 cells had a higher potential for hBD-2 induction following FliC stimulation than GD1a-loaded CHO-K1 cells not expressing TLR5. FliC increased phosphorylation of mitogen-activated protein kinase, p38, and ERK1/2. Exogenous gangliosides GD1a, GD1b, and GT1b each suppressed FliC induction of p38 and ERK1/2 phosphorylation. Furthermore, FliC did not enhance luciferase activity in Caco-2 cells transfected with a plasmid containing a mutated activator protein 1-binding site. These results suggest that gangliosides act as co-receptors with TLR5 for FliC and promote hBD-2 expression via mitogen-activated protein kinase.
authors.affiliation: Department of Bacteriology, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523, Japan.
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Ogushi
authors.forename: Akihiro
authors.initials: A
authors.lastname: Wada
authors.forename: Takuro
authors.initials: T
authors.lastname: Niidome
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Okuda
authors.forename: Rafael
authors.initials: R
authors.lastname: Llanes
authors.forename: Masaaki
authors.initials: M
authors.lastname: Nakayama
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Nishi
authors.forename: Hisao
authors.initials: H
authors.lastname: Kurazono
authors.forename: Kelly D
authors.initials: KD
authors.lastname: Smith
authors.forename: Alan
authors.initials: A
authors.lastname: Aderem
authors.forename: Joel
authors.initials: J
authors.lastname: Moss
authors.forename: Toshiya
authors.initials: T
authors.lastname: Hirayama
mesh_terms: D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D016466:CHO Cells; D018938:Caco-2 Cells; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D004306:Dose-Response Relationship, Immunologic; D005408:Flagellin / Q000378:metabolism*; D005434:Flow Cytometry; D005677:G(M1) Ganglioside / Q000031:analogs & derivatives* / Q000737:chemistry; D005964:Glucosyltransferases / Q000037:antagonists & inhibitors; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008562:Membrane Glycoproteins / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008957:Models, Genetic; D009025:Morpholines / Q000737:chemistry; D009154:Mutation; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D012477:Salmonella enteritidis / Q000378:metabolism*; D015398:Signal Transduction; D051198:Toll-Like Receptor 5; D051193:Toll-Like Receptors; D014162:Transfection; D023083:beta-Defensins / Q000378:metabolism*
chemical_list: C106641:DEFB4A protein, human; D008562:Membrane Glycoproteins; D009025:Morpholines; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; C495346:TLR5 protein, human; D051198:Toll-Like Receptor 5; D051193:Toll-Like Receptors; D023083:beta-Defensins; C064020:ganglioside GD1alpha; D005408:Flagellin; D005677:G(M1) Ganglioside; D008156:Luciferases; D005964:Glucosyltransferases; C023246:ceramide glucosyltransferase; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases