title: Ceramide 1-phosphate, a mediator of phagocytosis.
abstract: The agonist-stimulated metabolism of membrane lipids produces potent second messengers that regulate phagocytosis. We studied whether human ceramide kinase (hCERK) activity and ceramide 1-phosphate formation could lead to enhanced phagocytosis through a mechanism involving modulation of the membrane-structural order parameter. hCERK was stably transfected into COS-1 cells that were stably transfected with the FcgammaRIIA receptor. hCERK-transfected cells displayed a significant increase in phagocytic index in association with increased ceramide kinase activation and translocation to lipid rafts after activation with opsonized erythrocytes. When challenged with opsonized erythrocytes, hCERK-transfected cells increased phagocytosis by 1.5-fold compared with vector control and simultaneously increased ceramide 1-phosphate levels 2-fold compared with vector and unstimulated control cells. Control and hCERK-transfected cells were subjected to cellular fractionation. Utilizing an antibody against hCERK, we observed that CERK translocates during activation from the cytosol to a lipid raft fraction. The plasma membrane-structural order parameter of the transfectants was measured by labeling cells with Laurdan. Cells transfected with hCERK showed a higher liquid crystalline order than control cells with stimulation, conditions that are favorable for the promotion of membrane fusion at the sites of phagocytosis. The change in the structural order parameter of the lipid rafts probably contributes to phagocytosis by promoting phagosome formation.
authors.affiliation: Department of Pediatrics, Division of Hematology/Oncology, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298, USA.
authors.forename: Vania
authors.initials: V
authors.lastname: Hinkovska-Galcheva
authors.forename: Laurence A
authors.initials: LA
authors.lastname: Boxer
authors.forename: Andrei
authors.initials: A
authors.lastname: Kindzelskii
authors.forename: Miki
authors.initials: M
authors.lastname: Hiraoka
authors.forename: Akira
authors.initials: A
authors.lastname: Abe
authors.forename: Sravan
authors.initials: S
authors.lastname: Goparju
authors.forename: Sarah
authors.initials: S
authors.lastname: Spiegel
authors.forename: Howard R
authors.initials: HR
authors.lastname: Petty
authors.forename: James A
authors.initials: JA
authors.lastname: Shayman
mesh_terms: D015081:2-Naphthylamine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D015703:Antigens, CD / Q000737:chemistry; D019556:COS Cells; D002384:Catalysis; D051242:Caveolin 1; D022461:Caveolins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002518:Ceramides / Q000378:metabolism / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism; D005822:Genetic Vectors; D006801:Humans; D015151:Immunoblotting; D007700:Kinetics; D007848:Laurates / Q000494:pharmacology; D008055:Lipids / Q000737:chemistry; D021962:Membrane Microdomains / Q000378:metabolism; D010587:Phagocytosis; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D021381:Protein Transport; D017452:Receptors, IgG / Q000737:chemistry; D012756:Sheep; D013347:Subcellular Fractions; D013997:Time Factors; D014162:Transfection; D047392:beta-Cyclodextrins / Q000737:chemistry
chemical_list: D015703:Antigens, CD; D051242:Caveolin 1; D022461:Caveolins; D002518:Ceramides; D018076:DNA, Complementary; C080568:Fc gamma receptor IIA; D007848:Laurates; D008055:Lipids; D017452:Receptors, IgG; D047392:beta-Cyclodextrins; C065576:ceramide 1-phosphate; C108732:methyl-beta-cyclodextrin; D015081:2-Naphthylamine; D017853:Phosphotransferases (Alcohol Group Acceptor); C066324:ceramide kinase; C065580:laurdan