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

Am J Physiol Renal Physiol. 2014 May 1;306(9):F981-95. doi: 10.1152/ajprenal.00362.2013. Epub 2014 Feb 19.

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.

Keywords: AMPK; PKA; acid-base homeostasis; metabolic stress.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • 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*

Substances

  • Enzyme Activators
  • Isoenzymes
  • Phosphodiesterase Inhibitors
  • Protein Kinase Inhibitors
  • Cyclic AMP-Dependent Protein Kinases
  • AMP-Activated Protein Kinases
  • Vacuolar Proton-Translocating ATPases