Myosin-Va restrains the trafficking of Na+/K+-ATPase-containing vesicles in alveolar epithelial cells.
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.
Lecuona
Emilia
E
Division of Pulmonary and Critical Care Medicine, Department of Medicine, Northwestern University, Chicago, IL 60611, USA. e-lecuona@northwestern.edu
Minin
Alexander
A
Trejo
Humberto E
HE
Chen
Jiwang
J
Comellas
Alejandro P
AP
Sun
Haiying
H
Grillo
Doris
D
Nekrasova
Oxana E
OE
Welch
Lynn C
LC
Szleifer
Igal
I
Gelfand
Vladimir I
VI
Sznajder
Jacob I
JI
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*
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