AMP-activated protein kinase regulates the vacuolar H+-ATPase via direct phosphorylation of the A subunit (ATP6V1A) in the kidney

Rodrigo Alzamora, Mohammad M. Al-Bataineh, Wen Liu, Fan Gong, Hui Li, Ramon F. Thali, Yolanda Joho-Auchli, Rene A. Brunisholz, Lisa M. Satlin, Dietbert Neumann, Kenneth R. Hallows*, Nuria M. Pastor-Soler

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

37 Citations (Web of Science)

Abstract

The vacuolar H+-ATPase (V-ATPase) in intercalated cells contributes to luminal acidification in the kidney collecting duct and nonvolatile acid excretion. We previously showed that the A subunit in the cytoplasmic V1 sector of the V-ATPase (ATP6V1A) is phosphorylated by the metabolic sensor AMP-activated protein kinase (AMPK) in vitro and in kidney cells. Here, we demonstrate that treatment of rabbit isolated, perfused collecting ducts with the AMPK activator 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR) inhibited V-ATPase-dependent H+ secretion from intercalated cells after an acid load. We have identified by mass spectrometry that Ser-384 is a major AMPK phosphorylation site in the V-ATPase A subunit, a result confirmed by comparing AMPK-dependent phosphate labeling of wild-type A-subunit (WT-A) with that of a Ser-384to- Ala A subunit mutant (S384A-A) in vitro and in intact HEK-293 cells. Compared with WT-A-expressing HEK-293 cells, S384A-A-expressing cells exhibited greater steady-state acidification of HCO3--containing media. Moreover, AICAR treatment of clone C rabbit intercalated cells expressing the WT-A subunit reduced V-ATPase-dependent extracellular acidification, an effect that was blocked in cells expressing the phosphorylation-deficient S384A-A mutant. Finally, expression of the S384A-A mutant prevented cytoplasmic redistribution of the V-ATPase by AICAR in clone C cells. In summary, direct phosphorylation of the A subunit at Ser-384 by AMPK represents a novel regulatory mechanism of the V-ATPase in kidney intercalated cells. Regulation of the V-ATPase by AMPK may couple V-ATPase activity to cellular metabolic status with potential relevance to ischemic injury in the kidney and other tissues.
Original languageEnglish
Pages (from-to)F943-F956
JournalAmerican Journal of Physiology-Renal Physiology
Volume305
Issue number7
DOIs
Publication statusPublished - Oct 2013

Keywords

  • AMPK
  • kidney
  • mass spectrometry
  • V-ATPase
  • Intercalated cells

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