title: Evidence for the presence of functional lipid rafts in immune cells of ectothermic organisms.
abstract: The role of lipid rafts in non-mammalian leukocytes has been scarcely investigated. We performed biochemical and functional analysis of lipid rafts in fish leukocytes. Fish Flotillin-1 and a fish GM1-like molecule (fGM1-L) were found in low density detergent-resistant membranes (LD-DRM) in goldfish macrophages and catfish B lymphocytes, similarly to mammals. The presence of flotillin-1 and fGM1-L in LD-DRM was sensitive to increased detergent concentrations, and cholesterol extraction. Confocal microscopy analysis of flotillin-1 and fGM1-L in fish leukocytes showed a distinctive punctuated staining pattern, suggestive of pre-existing rafts. Confocal microscopy analysis of macrophages showed that the membrane of phagosomes containing serum-opsonized zymosan was enriched in fGM1-L, and zymosan phagocytosis was reduced after cholesterol extraction. The presence of flotillin-1 and fGM1-L in LD-DRM, the microscopic evidence of flotillin-1 and fGM1-L on fish macrophages and B-cells, and the sensitivity of phagocytosis to cholesterol extraction, indicate that lipid rafts are biochemically and functionally similar in leukocytes from fish and mammals.
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Canada AB T6G 2E9.
authors.forename: Erick
authors.initials: E
authors.lastname: Garcia-Garcia
authors.forename: Leon
authors.initials: L
authors.lastname: Grayfer
authors.forename: James L
authors.initials: JL
authors.lastname: Stafford
authors.forename: Miodrag
authors.initials: M
authors.lastname: Belosevic
mesh_terms: D000818:Animals; D051242:Caveolin 1 / Q000032:analysis; D029941:Fish Proteins / Q000378:metabolism; D005677:G(M1) Ganglioside / Q000032:analysis; D006054:Goldfish / Q000276:immunology* / Q000378:metabolism*; D006801:Humans; D007962:Leukocytes / Q000737:chemistry* / Q000166:cytology; D021962:Membrane Microdomains / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins / Q000032:analysis
chemical_list: D051242:Caveolin 1; D029941:Fish Proteins; D008565:Membrane Proteins; C106354:flotillins; D005677:G(M1) Ganglioside