title: Spreading of porous vesicles subjected to osmotic shocks: the role of aquaporins.
abstract: Aquaporin 0 (AQP0) is a transmembrane protein specific to the eye lens, involved as a water carrier across the lipid membranes. During eye lens maturation, AQP0s are truncated by proteolytic cleavage. We investigate in this work the capability of truncated AQP0 to conduct water across membranes. We developed a method to accurately determine water permeability across lipid membranes and across proteins from the deflation under osmotic pressure of giant unilamellar vesicles (GUVs) deposited on an adhesive substrate. Using reflection interference contrast microscopy (RICM), we measure the spreading area of GUVs during deswelling. We interpret these results using a model based on hydrodynamic, binder diffusion towards the contact zone, and Helfrich's law for the membrane tension, which allows us to relate the spread area to the vesicle internal volume. We first study the specific adhesion of vesicles coated with biotin spreading on a streptavidin substrate. We then determine the permeability of a single functional AQP0 and demonstrate that truncated AQP0 is no more a water channel.
authors.affiliation: Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, 75005, Paris, France. stephanie.mangenot@curie.fr.
authors.forename: Alice
authors.initials: A
authors.lastname: Berthaud
authors.forename: François
authors.initials: F
authors.lastname: Quemeneur
authors.forename: Maxime
authors.initials: M
authors.lastname: Deforet
authors.forename: Patricia
authors.initials: P
authors.lastname: Bassereau
authors.forename: Françoise
authors.initials: F
authors.lastname: Brochard-Wyart
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Mangenot
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D005136:Eye Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D007908:Lens, Crystalline / Q000378:metabolism; D008857:Microscopy, Interference; D009997:Osmotic Pressure; D010539:Permeability; D016062:Porosity; D012756:Sheep; D013388:Succinimides / Q000737:chemistry; D053835:Unilamellar Liposomes / Q000737:chemistry / Q000378:metabolism; D014867:Water / Q000737:chemistry
chemical_list: C492694:Alexa Fluor 488 carboxylic acid succinimidyl ester; D020346:Aquaporins; D005136:Eye Proteins; D013388:Succinimides; D053835:Unilamellar Liposomes; C030328:aquaporin 0; D014867:Water