title: Phosphatidylinositol-3,4,5-trisphosphate regulates the formation of the basolateral plasma membrane in epithelial cells.
abstract: Polarity is a central feature of eukaryotic cells and phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) has a central role in the polarization of neurons and chemotaxing cells. In polarized epithelial cells, PtdIns(3,4,5)P3 is stably localized at the basolateral plasma membrane, but excluded from the apical plasma membrane, as shown by localization of GFP fused to the PtdIns(3,4,5)P3-binding pleckstrin-homology domain of Akt (GFP-PH-Akt), a fusion protein that indicates the location of PtdIns(3,4,5)P3. Here, we ectopically inserted exogenous PtdIns(3,4,5)P3 into the apical plasma membrane of polarized Madin-Darby canine kidney (MDCK) cells. Within 5 min many cells formed protrusions that extended above the apical surface. These protrusions contained basolateral plasma membrane proteins and excluded apical proteins, indicating that their plasma membrane was transformed from apical to basolateral. Addition of PtdIns(3,4,5)P3 to the basolateral surface of MDCK cells grown as cysts caused basolateral protrusions. MDCK cells grown in the presence of a phosphatidylinositol 3-kinase inhibitor had abnormally short lateral surfaces, indicating that PtdIns(3,4,5)P3 regulates the formation of the basolateral surface.
authors.affiliation: Department of Anatomy, University of California, San Francisco, CA, 94143, USA. gassama@toulouse.inserm.fr
authors.forename: Ama
authors.initials: A
authors.lastname: Gassama-Diagne
authors.forename: Wei
authors.initials: W
authors.lastname: Yu
authors.forename: Martin
authors.initials: M
authors.lastname: ter Beest
authors.forename: Fernando
authors.initials: F
authors.lastname: Martin-Belmonte
authors.forename: Arlinet
authors.initials: A
authors.lastname: Kierbel
authors.forename: Joanne
authors.initials: J
authors.lastname: Engel
authors.forename: Keith
authors.initials: K
authors.lastname: Mostov
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology*; D016764:Cell Polarity; D022081:Cell Surface Extensions / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D004285:Dogs; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000378:metabolism; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000494:pharmacology / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors
chemical_list: D008565:Membrane Proteins; D019869:Phosphatidylinositol 3-Kinases; D018129:Phosphatidylinositol Phosphates; D000081082:Phosphoinositide-3 Kinase Inhibitors; C060974:phosphatidylinositol 3,4,5-triphosphate