title: Regulation of proximal tubule vacuolar H(+)-ATPase by PKA and AMP-activated protein kinase.
abstract: The vacuolar H(+)-ATPase (V-ATPase) mediates ATP-driven H(+) transport across membranes. This pump is present at the apical membrane of kidney proximal tubule cells and intercalated cells. Defects in the V-ATPase and in proximal tubule function can cause renal tubular acidosis. We examined the role of protein kinase A (PKA) and AMP-activated protein kinase (AMPK) in the regulation of the V-ATPase in the proximal tubule as these two kinases coregulate the V-ATPase in the collecting duct. As the proximal tubule V-ATPases have different subunit compositions from other nephron segments, we postulated that V-ATPase regulation in the proximal tubule could differ from other kidney tubule segments. Immunofluorescence labeling of rat ex vivo kidney slices revealed that the V-ATPase was present in the proximal tubule both at the apical pole, colocalizing with the brush-border marker wheat germ agglutinin, and in the cytosol when slices were incubated in buffer alone. When slices were incubated with a cAMP analog and a phosphodiesterase inhibitor, the V-ATPase accumulated at the apical pole of S3 segment cells. These PKA activators also increased V-ATPase apical membrane expression as well as the rate of V-ATPase-dependent extracellular acidification in S3 cell monolayers relative to untreated cells. However, the AMPK activator AICAR decreased PKA-induced V-ATPase apical accumulation in proximal tubules of kidney slices and decreased V-ATPase activity in S3 cell monolayers. Our results suggest that in proximal tubule the V-ATPase subcellular localization and activity are acutely coregulated via PKA downstream of hormonal signals and via AMPK downstream of metabolic stress.
authors.affiliation: Renal-Electrolyte Div., Dept. of Medicine, Scaife Hall A915, 3550 Terrace St., Pittsburgh, PA 15263. pastorn@pitt.edu.
authors.forename: Mohammad M
authors.initials: MM
authors.lastname: Al-bataineh
authors.forename: Fan
authors.initials: F
authors.lastname: Gong
authors.forename: Allison L
authors.initials: AL
authors.lastname: Marciszyn
authors.forename: Michael M
authors.initials: MM
authors.lastname: Myerburg
authors.forename: Núria M
authors.initials: NM
authors.lastname: Pastor-Soler
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000201:enzymology*; D051379:Mice; D008871:Microvilli / Q000201:enzymology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism*
chemical_list: D020536:Enzyme Activators; D007527:Isoenzymes; D010726:Phosphodiesterase Inhibitors; D047428:Protein Kinase Inhibitors; D017868:Cyclic AMP-Dependent Protein Kinases; D055372:AMP-Activated Protein Kinases; D025262:Vacuolar Proton-Translocating ATPases
keywords: AMPK; PKA; acid-base homeostasis; metabolic stress