title: Protein kinase A-dependent and -independent activation of the V-ATPase in Malpighian tubules of Aedes aegypti.
abstract: Transepithelial ion transport in insect Malpighian tubules is energized by an apical V-ATPase. In hematophagous insects, a blood meal during which the animal ingests huge amounts of salt and water stimulates transepithelial transport processes linked to V-ATPase activation, but how this is accomplished is still unclear. Here we report that membrane-permeant derivatives of cAMP increase the bafilomycin-sensitive ATPase activity in Malpighian tubules of Aedes aegypti twofold and activate ATP-dependent transport processes. In parallel, membrane association of the V(1) subunits C and D increases, consistent with the assembly of the holoenzyme. The protein kinase A inhibitor H-89 abolishes all cAMP-induced effects, consistent with protein kinase A (PKA) being involved in V-ATPase activation. Metabolic inhibition induced by KCN, azide and 2,4-dinitrophenol, respectively, also induces assembly of functional V-ATPases at the membrane without PKA involvement, indicating a phosphorylation-independent activation mechanism.
authors.affiliation: Department of Biology/Chemistry, Division of Animal Physiology, University of Osnabrück, 49069 Osnabrück,  Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Tiburcy
authors.forename: Klaus W
authors.initials: KW
authors.lastname: Beyenbach
authors.forename: Helmut
authors.initials: H
authors.lastname: Wieczorek
mesh_terms: D000330:Aedes / Q000502:physiology*; D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004231:Diuresis; D005260:Female; D008317:Malpighian Tubules / Q000201:enzymology* / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism*
chemical_list: D012701:Serotonin; D017868:Cyclic AMP-Dependent Protein Kinases; D025262:Vacuolar Proton-Translocating ATPases