Role of intracellular Ca2+ in the expression of the amiloride-sensitive epithelial sodium channel

U. Subrahmanyeswara Rao, James M. Baker, Jennifer L. Pluznick, Premalatha Balachandran

Research output: Contribution to journalArticlepeer-review

Abstract

The amiloride-sensitive epithelial sodium channel (ENaC), a multimeric plasma membrane protein composed of α-, β-, and γ-ENaC subunits, mediates Na+ reabsorption in epithelial tissues, including the distal nephron, colon, lung, and secretory glands, and plays a critical role in pathophysiology of essential hypertension and cystic fibrosis (CF). The function of ENaC is tightly regulated by signals elicited by aldosterone, vasopressin, agents that increase intracellular cAMP levels, ions, ion channels, G-protein-coupled mechanisms, and cytoskeletal proteins. In this paper, the effects of Ca2+ on the expression of the human ENaC subunits expressed in human embryonic kidney cells (HEK-293 cells) were examined. Incubation of cells with increased extracellular Ca2+ and treatment of cells with A23187 and thapsigargin stimulated the expression of the monomeric ENaC subunits. Treatment of cells with Ca2+-chelating agents, EGTA and BAPTA-AM, reduced the levels of ENaC subunit expression. The pulse-chase experiments suggested that a rise in the intracellular Ca2+ increases the ENaC subunit expression. Immunoblot analysis using the anti-ubiquitin antibody indicated that ENaC undergoes ubiquitination. A correlation between the processes that regulate ENaC function with the intracellular Ca2+ was discussed.

Original languageEnglish (US)
Pages (from-to)21-28
Number of pages8
JournalCell Calcium
Volume35
Issue number1
DOIs
StatePublished - Jan 2004
Externally publishedYes

Keywords

  • Amiloride-sensitive epithelial sodium channel
  • Cystic fibrosis
  • HEK-293 cells
  • Intracellular Ca

ASJC Scopus subject areas

  • Physiology
  • Molecular Biology
  • Cell Biology

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