title: Exogenous lysophospholipids with large head groups perturb clathrin-mediated endocytosis.
abstract: In this study, we have investigated how clathrin-dependent endocytosis is affected by exogenously added lysophospholipids (LPLs). Addition of LPLs with large head groups strongly inhibits transferrin (Tf) endocytosis in various cell lines, while LPLs with small head groups do not. Electron and total internal reflection fluorescence microscopy (EM and TIRF) reveal that treatment with lysophosphatidylinositol (LPI) with the fatty acyl group C18:0 leads to reduced numbers of invaginated clathrin-coated pits (CCPs) at the plasma membrane, fewer endocytic events per membrane area and increased lifetime of CCPs. Also, endocytosis of Tf becomes dependent on actin upon LPI treatment. Thus, our results demonstrate that one can regulate the kinetics and properties of clathrin-dependent endocytosis by addition of LPLs in a head group size- and fatty acyl-dependent manner. Furthermore, studies performed with optical tweezers show that less force is required to pull membrane tubules outwards from the plasma membrane when LPI is added to the cells. The results are in agreement with the notion that insertion of LPLs with large head groups creates a positive membrane curvature which might have a negative impact on events that require plasma membrane invagination, while it may facilitate membrane bending toward the cell exterior.
authors.affiliation: Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway.|Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.|Department of Biosciences, University of Oslo, Oslo, Norway.
authors.forename: Ieva
authors.identifier: 0000-0002-3516-4983
authors.initials: I
authors.lastname: Ailte
authors.affiliation: Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway.|Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
authors.forename: Anne Berit D
authors.initials: AB
authors.lastname: Lingelem
authors.affiliation: Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway.|Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
authors.forename: Audun S
authors.initials: AS
authors.lastname: Kvalvaag
authors.affiliation: Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway.|Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.|Department of Biosciences, University of Oslo, Oslo, Norway.
authors.forename: Simona
authors.initials: S
authors.lastname: Kavaliauskiene
authors.affiliation: Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway.|Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.|Department of Biosciences, University of Oslo, Oslo, Norway.
authors.forename: Andreas
authors.initials: A
authors.lastname: Brech
authors.affiliation: Department of Biosciences, University of Oslo, Oslo, Norway.
authors.forename: Gerbrand
authors.initials: G
authors.lastname: Koster
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Dommersnes
authors.affiliation: Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway.|Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
authors.forename: Jonas
authors.initials: J
authors.lastname: Bergan
authors.affiliation: Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway.|Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
authors.forename: Tore
authors.initials: T
authors.lastname: Skotland
authors.affiliation: Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway.|Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.|Department of Biosciences, University of Oslo, Oslo, Norway.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Sandvig
mesh_terms: D000199:Actins / Q000378:metabolism; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism / Q000502:physiology; D002966:Clathrin / Q000378:metabolism*; D003034:Coated Pits, Cell-Membrane / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D008246:Lysophospholipids / Q000378:metabolism*; D014168:Transferrin / Q000378:metabolism
chemical_list: D000199:Actins; D002966:Clathrin; D008246:Lysophospholipids; D014168:Transferrin; C025449:lysophosphatidylinositol
keywords: 
  AP2
  ; actin; clathrin; endocytosis; lysophosphatidylinositol; lysophospholipids; plasma membrane; transferrin