title: Myosin-Va restrains the trafficking of Na+/K+-ATPase-containing vesicles in alveolar epithelial cells.
abstract: Stimulation of Na(+)/K(+)-ATPase activity in alveolar epithelial cells by cAMP involves its recruitment from intracellular compartments to the plasma membrane. Here, we studied the role of the actin molecular motor myosin-V in this process. We provide evidence that, in alveolar epithelial cells, cAMP promotes Na(+)/K(+)-ATPase recruitment to the plasma membrane by increasing the average speed of Na(+)/K(+)-ATPase-containing vesicles moving to the cell periphery. We found that three isoforms of myosin-V are expressed in alveolar epithelial cells; however, only myosin-Va and Vc colocalized with the Na(+)/K(+)-ATPase in intracellular membrane fractions. Overexpression of dominant-negative myosin-Va or knockdown with specific shRNA increased the average speed and distance traveled by the Na(+)/K(+)-ATPase-containing vesicles, as well as the Na(+)/K(+)-ATPase activity and protein abundance at the plasma membrane to similar levels as those observed with cAMP stimulation. These data show that myosin-Va has a role in restraining Na(+)/K(+)-ATPase-containing vesicles within intracellular pools and that this restrain is released after stimulation by cAMP allowing the recruitment of the Na(+)/K(+)-ATPase to the plasma membrane and thus increased activity.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Northwestern University, Chicago, IL 60611, USA. e-lecuona@northwestern.edu
authors.forename: Emilia
authors.initials: E
authors.lastname: Lecuona
authors.forename: Alexander
authors.initials: A
authors.lastname: Minin
authors.forename: Humberto E
authors.initials: HE
authors.lastname: Trejo
authors.forename: Jiwang
authors.initials: J
authors.lastname: Chen
authors.forename: Alejandro P
authors.initials: AP
authors.lastname: Comellas
authors.forename: Haiying
authors.initials: H
authors.lastname: Sun
authors.forename: Doris
authors.initials: D
authors.lastname: Grillo
authors.forename: Oxana E
authors.initials: OE
authors.lastname: Nekrasova
authors.forename: Lynn C
authors.initials: LC
authors.lastname: Welch
authors.forename: Igal
authors.initials: I
authors.lastname: Szleifer
authors.forename: Vladimir I
authors.initials: VI
authors.lastname: Gelfand
authors.forename: Jacob I
authors.initials: JI
authors.lastname: Sznajder
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D022162:Cytoplasmic Vesicles / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000201:enzymology* / Q000378:metabolism; D006801:Humans; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism*; D024701:Myosin Type V / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D011650:Pulmonary Alveoli / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000378:metabolism*
chemical_list: D020033:Protein Isoforms; C077511:MYO5A protein, human; D000242:Cyclic AMP; C499075:Atp1a1 protein, rat; D024701:Myosin Type V; D018995:Myosin Heavy Chains; D000254:Sodium-Potassium-Exchanging ATPase