Purinergic control of apical plasma membrane PI(4,5)P2 levels sets ENaC activity in principal cells

Oleh Pochynyuk, Vladislav Bugaj, Alain Vandewalle, James D. Stockand

Research output: Contribution to journalArticle

58 Scopus citations

Abstract

Activity of the epithelial sodium channel (ENaC) is limiting for Na + reabsorption at the distal nephron. Phosphoinositides, such as phosphatidylinositol 4,5-biphosphate [PI(4,5)P2] modulate the activity of this channel. Activation of purinergic receptors triggers multiple events, including activation of PKC and PLC, with the latter depleting plasma membrane PI(4,5)P2. Here, we investigate regulation of ENaC in renal principal cells by purinergic receptors via PLC and PI(4,5)P2. Purinergic signaling rapidly decreases ENaC open probability and apical membrane PI(4,5)P2 levels with similar time courses. Moreover, inhibiting purinergic signaling with suramin rescues ENaC activity. The PLC inhibitor U73122, but not U73343, its inactive analog, recapitulates the action of suramin. In contrast, modulating PKC signaling failed to affect purinergic regulation of ENaC. Unexpectedly, inhibiting either purinergic receptors or PLC in resting cells dramatically increased ENaC activity above basal levels, indicating tonic activation of purinergic signaling in these polarized renal epithelial cells. Increased ENaC activity was associated with elevation of apical membrane PI(4,5)P2 levels. Subsequent treatment with ATP in the presence of inhibited purinergic signaling failed to decrease ENaC activity and apical membrane PI(4,5)P2 levels. Dwell-time analysis reveals that depletion of PI(4,5)P2 forces ENaC toward a closed state. In contrast, increasing PI(4,5)P2 levels above basal values locks the channel in an open state interrupted by brief closings. Thus our results suggest that purinergic control of apical membrane PI(4,5)P2 levels is a major regulator of ENaC activity in renal epithelial cells.

Original languageEnglish (US)
Pages (from-to)F38-F46
JournalAmerican Journal of Physiology - Renal Physiology
Volume294
Issue number1
DOIs
StatePublished - Jan 1 2008

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Keywords

  • Hypertension
  • P2Y receptors
  • PLC signaling
  • Phosphoinositides
  • Sodium reabsorption

ASJC Scopus subject areas

  • Physiology
  • Urology

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