title: Translocation of aquaporin-containing vesicles to the plasma membrane is facilitated by actomyosin relaxation.
abstract: Docking and fusion of vesicles to the plasma membrane is a fundamental process in living cells. An established model for the trafficking of vesicles is based on primary epithelial cells from the collecting duct of the nephron. Upon stimulation with the signaling peptide arginine-vasopressin (AVP), aquaporin-containing vesicles are directed to the plasma membrane. Since aquaporin selectively enhances the water permeability of plasma membranes, this process helps to balance the water content of the organism. A mechanism has been suggested involving local depolymerization of F-actin to facilitate the movement of vesicles to the membrane. Since F-actin is the major component of cytoskeletal restoring forces, AVP-stimulated cells can be expected to lose rigidity. Here, we used atomic force microscopy force mapping to test whether AVP alters cell stiffness. The Young's modulus of living epithelial cells at 37 degrees C was continuously monitored, yielding a 51% decrease of Young's modulus after the addition of AVP. The data demonstrate that not the depolymerization of actin but a relaxation of actomyosin interaction facilitates vesicle translocation.
authors.affiliation: Institute of Physiology II, University of Münster, Munich, Germany. chrth@uni-muenster.de
authors.forename: Christoph
authors.initials: C
authors.lastname: Riethmüller
authors.forename: Hans
authors.initials: H
authors.lastname: Oberleithner
authors.forename: Marianne
authors.initials: M
authors.lastname: Wilhelmi
authors.forename: Jonas
authors.initials: J
authors.lastname: Franz
authors.forename: Eberhard
authors.initials: E
authors.lastname: Schlatter
authors.forename: Jens
authors.initials: J
authors.lastname: Klokkers
authors.forename: Bayram
authors.initials: B
authors.lastname: Edemir
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000205:Actomyosin / Q000378:metabolism*; D000818:Animals; D020346:Aquaporins / Q000378:metabolism*; D001696:Biomechanical Phenomena; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D002470:Cell Survival; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000648:ultrastructure; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D021381:Protein Transport; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D022161:Transport Vesicles / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D020346:Aquaporins; D000205:Actomyosin