title: Microtubule motors power plasma membrane tubulation in clathrin-independent endocytosis.
abstract: How the plasma membrane is bent to accommodate clathrin-independent endocytosis remains uncertain. Recent studies suggest Shiga and cholera toxin induce membrane curvature required for their uptake into clathrin-independent carriers by binding and cross-linking multiple copies of their glycosphingolipid receptors on the plasma membrane. But it remains unclear if toxin-induced sphingolipid crosslinking provides sufficient mechanical force for deforming the plasma membrane, or if host cell factors also contribute to this process. To test this, we imaged the uptake of cholera toxin B-subunit into surface-derived tubular invaginations. We found that cholera toxin mutants that bind to only one glycosphingolipid receptor accumulated in tubules, and that toxin binding was entirely dispensable for membrane tubulations to form. Unexpectedly, the driving force for tubule extension was supplied by the combination of microtubules, dynein and dynactin, thus defining a novel mechanism for generating membrane curvature during clathrin-independent endocytosis.
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA.|Current address: Hormel Institute, University of Minnesota, Austin, MN, USA.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Day
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Nicholas W
authors.initials: NW
authors.lastname: Baetz
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Courtney A
authors.initials: CA
authors.lastname: Copeland
authors.affiliation: Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN, USA.
authors.forename: Lewis J
authors.initials: LJ
authors.lastname: Kraft
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Bing
authors.initials: B
authors.lastname: Han
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Ajit
authors.initials: A
authors.lastname: Tiwari
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Kimberly R
authors.initials: KR
authors.lastname: Drake
authors.affiliation: GI Cell Biology, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA.
authors.forename: Heidi
authors.initials: H
authors.lastname: De Luca
authors.affiliation: GI Cell Biology, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA.
authors.forename: Daniel J-F
authors.initials: DJ
authors.lastname: Chinnapen
authors.affiliation: National High Magnetic Field Laboratory, The Florida State University, Tallahassee, FL, USA.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Davidson
authors.affiliation: Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, USA.
authors.forename: Randall K
authors.initials: RK
authors.lastname: Holmes
authors.affiliation: Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, USA.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Jobling
authors.affiliation: Department of Biology, The Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Trina A
authors.initials: TA
authors.lastname: Schroer
authors.affiliation: GI Cell Biology, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA.|Harvard Medical School and the Harvard Digestive Diseases Center, Boston, MA, USA.
authors.forename: Wayne I
authors.initials: WI
authors.lastname: Lencer
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA.|Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN, USA.|Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA.|Epithelial Biology Program, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Anne K
authors.initials: AK
authors.lastname: Kenworthy
mesh_terms: D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism*; D002522:Chlorocebus aethiops; D002772:Cholera Toxin / Q000378:metabolism; D002966:Clathrin / Q000378:metabolism; D004398:Dyneins / Q000378:metabolism; D004705:Endocytosis; D006367:HeLa Cells; D006801:Humans; D008870:Microtubules / Q000378:metabolism*; D011485:Protein Binding; D011990:Receptors, Transferrin / Q000378:metabolism
chemical_list: D002966:Clathrin; D011990:Receptors, Transferrin; D002772:Cholera Toxin; D004398:Dyneins
keywords: cholera toxin; clathrin-independent endocytosis; dynactin; dynein; membrane curvature; microtubules