title: Disruption of Sphingolipid Biosynthesis Blocks Phagocytosis of Candida albicans.
abstract: The ability of phagocytes to clear pathogens is an essential attribute of the innate immune response. The role of signaling lipid molecules such as phosphoinositides is well established, but the role of membrane sphingolipids in phagocytosis is largely unknown. Using a genetic approach and small molecule inhibitors, we show that phagocytosis of Candida albicans requires an intact sphingolipid biosynthetic pathway. Blockade of serine-palmitoyltransferase (SPT) and ceramide synthase-enzymes involved in sphingolipid biosynthesis- by myriocin and fumonisin B1, respectively, impaired phagocytosis by phagocytes. We used CRISPR/Cas9-mediated genome editing to generate Sptlc2-deficient DC2.4 dendritic cells, which lack serine palmitoyl transferase activity. Sptlc2-/- DC2.4 cells exhibited a stark defect in phagocytosis, were unable to bind fungal particles and failed to form a normal phagocytic cup to engulf C. albicans. Supplementing the growth media with GM1, the major ganglioside present at the cell surface, restored phagocytic activity of Sptlc2-/- DC2.4 cells. While overall membrane trafficking and endocytic pathways remained functional, Sptlc2-/- DC2.4 cells express reduced levels of the pattern recognition receptors Dectin-1 and TLR2 at the cell surface. Consistent with the in vitro data, compromised sphingolipid biosynthesis in mice sensitizes the animal to C. albicans infection. Sphingolipid biosynthesis is therefore critical for phagocytosis and in vivo clearance of C. albicans.
authors.affiliation: Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America; Ragon Institute of MGH, MIT and Harvard, Cambridge, Massachusetts, United States of America.
authors.forename: Fikadu G
authors.initials: FG
authors.lastname: Tafesse
authors.affiliation: Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America; Ragon Institute of MGH, MIT and Harvard, Cambridge, Massachusetts, United States of America.
authors.forename: Ali
authors.initials: A
authors.lastname: Rashidfarrokhi
authors.affiliation: Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors.forename: Florian I
authors.initials: FI
authors.lastname: Schmidt
authors.affiliation: Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors.forename: Elizaveta
authors.initials: E
authors.lastname: Freinkman
authors.affiliation: Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Dougan
authors.affiliation: Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors.forename: Michael
authors.initials: M
authors.lastname: Dougan
authors.affiliation: Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Esteban
authors.affiliation: Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Maruyama
authors.affiliation: Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors.forename: Karin
authors.initials: K
authors.lastname: Strijbis
authors.affiliation: Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors.forename: Hidde L
authors.initials: HL
authors.lastname: Ploegh
mesh_terms: D000818:Animals; D002176:Candida albicans / Q000276:immunology; D002177:Candidiasis / Q000276:immunology*; D002460:Cell Line; D002855:Chromatography, Thin Layer; D003713:Dendritic Cells / Q000276:immunology / Q000382:microbiology; D004195:Disease Models, Animal; D005434:Flow Cytometry; D055786:Gene Knockout Techniques; D054884:Host-Pathogen Interactions / Q000276:immunology*; D006801:Humans; D013058:Mass Spectrometry; D051379:Mice; D010587:Phagocytosis / Q000502:physiology*; D013107:Sphingolipids / Q000096:biosynthesis*
chemical_list: D013107:Sphingolipids