Regulation of proximal tubule vacuolar H(+)-ATPase by PKA and AMP-activated protein kinase

• Published in: American journal of physiology. Renal physiology Vol. 306; no. 9; p. F981
• Main Authors: Al-bataineh, Mohammad M, Gong, Fan, Marciszyn, Allison L, Myerburg, Michael M, Pastor-Soler, Núria M
• Format: Journal Article
• Language: English
• Published: United States 01-05-2014
• Subjects: AMP-Activated Protein Kinases - antagonists & inhibitors; AMP-Activated Protein Kinases - metabolism; Animals; Cell Line; Cyclic AMP-Dependent Protein Kinases - antagonists & inhibitors; Cyclic AMP-Dependent Protein Kinases - metabolism; Cytosol - enzymology; Enzyme Activation; Enzyme Activators - pharmacology; Hydrogen-Ion Concentration; Isoenzymes; Kidney Tubules, Proximal - drug effects; Kidney Tubules, Proximal - enzymology; Mice; Microvilli - enzymology; Phosphodiesterase Inhibitors - pharmacology; Protein Kinase Inhibitors - pharmacology; Protein Transport; Rats; Rats, Sprague-Dawley; Signal Transduction; Vacuolar Proton-Translocating ATPases - metabolism; AMPK; metabolic stress; acid-base homeostasis; PKA
• ISSN: 1522-1466
• DOI: 10.1152/ajprenal.00362.2013

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.