α-Ketoglutarate stimulates pendrin-dependent Cl- absorption in the mouse CCD through protein kinase C

Am J Physiol Renal Physiol. 2018 Jul 1;315(1):F7-F15. doi: 10.1152/ajprenal.00576.2017. Epub 2018 Feb 7.

Abstract

α-Ketoglutarate (α-KG) is a citric acid cycle intermediate and a glutamine catabolism product. It is also the natural ligand of 2-oxoglutarate receptor 1 (OXGR1), a Gq protein-coupled receptor expressed on the apical membrane of intercalated cells. In the cortical collecting duct (CCD), Cl-/[Formula: see text] exchange increases upon α-KG binding to the OXGR1. To determine the signaling pathway(s) by which α-KG stimulates Cl- absorption, we examined α-KG-stimulated Cl- absorption in isolated perfused mouse CCDs. α-KG increased electroneutral Cl- absorption in CCDs from wild-type mice but had no effect on Cl- absorption in pendrin knockout mice. Because Gq protein-coupled receptors activate PKC, we hypothesized that α-KG stimulates Cl- absorption through PKC. If so, PKC agonists should mimic, whereas PKC inhibitors should abolish, α-KG-stimulated Cl- absorption. Like α-KG, PKC agonist (phorbol-12,13-dibutyrate, 500 nM) application increased Cl- absorption in wild-type but not in pendrin null CCDs. Moreover, PKC inhibitors (2.5 mM GF109203X and 20 nM calphostin C), Ca2+ chelators (BAPTA, 10-20 μM), or PKC-α or -δ gene ablation eliminated α-KG-stimulated Cl- absorption. We have shown that STE20/SPS-1-related proline-alanine-rich protein kinase (SPAK) gene ablation increases urinary α-KG excretion, renal pendrin abundance, and CCD Cl- absorption. However, in SPAK null CCDs, Cl- absorption was not activated further by luminal α-KG application nor was Cl- absorption reduced with the PKC inhibitor GF109203 . Thus SPAK gene ablation likely acts through a PKC-independent pathway to produce a chronic adaptive increase in pendrin function. In conclusion, α-KG stimulates pendrin-dependent Cl-/[Formula: see text] exchange through a mechanism dependent on PKC and Ca2+ that involves PKC-α and PKC-δ.

Publication types

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

MeSH terms

  • Animals
  • Calcium / metabolism
  • Chlorides / metabolism*
  • In Vitro Techniques
  • Ketoglutaric Acids / metabolism
  • Ketoglutaric Acids / pharmacology*
  • Kidney Tubules, Collecting / drug effects*
  • Kidney Tubules, Collecting / metabolism
  • Mice, 129 Strain
  • Mice, Inbred C57BL
  • Protein Kinase C-alpha / deficiency
  • Protein Kinase C-alpha / genetics
  • Protein Kinase C-alpha / metabolism*
  • Protein Kinase C-delta / deficiency
  • Protein Kinase C-delta / genetics
  • Protein Kinase C-delta / metabolism*
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism
  • Receptors, Purinergic P2 / drug effects
  • Receptors, Purinergic P2 / metabolism
  • Renal Reabsorption / drug effects*
  • Signal Transduction / drug effects
  • Sulfate Transporters / deficiency
  • Sulfate Transporters / genetics
  • Sulfate Transporters / metabolism*

Substances

  • Chlorides
  • Ketoglutaric Acids
  • OXGR1 protein, mouse
  • Receptors, Purinergic P2
  • Slc26a4 protein, mouse
  • Sulfate Transporters
  • Prkcd protein, mouse
  • Stk39 protein, mouse
  • Protein Serine-Threonine Kinases
  • Prkca protein, mouse
  • Protein Kinase C-alpha
  • Protein Kinase C-delta
  • Calcium