Superoxide flux in endothelial cells via the chloride channel-3 mediates intracellular signaling

Brian J. Hawkins, Muniswamy Madesh, C. J. Kirkpatrick, Aron B. Fisher

Research output: Contribution to journalArticle

128 Scopus citations

Abstract

Reactive oxygen species (ROS) have been implicated in both cell signaling and pathology. A major source of ROS in endothelial cells is NADPH oxidase, which generates superoxide (O2.-) on the extracellular side of the plasma membrane but can result in intracellular signaling. To study possible transmembrane flux of O2.-, pulmonary microvascular endothelial cells were preloaded with the O2 .--sensitive fluorophore hydroethidine (HE). Application of an extracellular bolus of O2.- resulted in rapid and concentration-dependent transient HE oxidation that was followed by a progressive and nonreversible increase in nuclear HE fluorescence. These fluorescence changes were inhibited by superoxide dismutase (SOD), the anion channel blocker DIDS, and selective silencing of the chloride channel-3 (ClC-3) by treatment with siRNA. Extracellular O2.- triggered Ca2+ release in turn triggered mitochondrial membrane potential alterations that were followed by mitochondrial O2.- production and cellular apoptosis. These "signaling" effects of O 2.- were prevented by DIDS treatment, by depletion of intracellular Ca2+ stores with thapsigargin and by chelation of intracellular Ca2+. This study demonstrates that O2 .- flux across the endothelial cell plasma membrane occurs through ClC-3 channels and induces intracellular Ca2+ release, which activates mitochondrial O2.- generation.

Original languageEnglish (US)
Pages (from-to)2002-2012
Number of pages11
JournalMolecular Biology of the Cell
Volume18
Issue number6
DOIs
StatePublished - Jun 1 2007

    Fingerprint

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Cite this