Oxidation induces ClC-3-dependent anion channels in human leukaemia cells

To test for redox regulation of anion channels in erythroid cells, we exposed K562 cells to oxidants and measured changes in transmembrane Cl− currents using patch-clamp, and in intracellular Cl− content using the Cl− selective dye MQAE. Oxidation with tert-butylhydroperoxide or H2O2 produced a plasma membrane anion permeability with a permselectivity of NO3->lactate->gluconate-. The permeability increase was paralleled by insertion of ClC-3 protein into the plasma membrane as evident from immunofluorescence microscopy and surface biotinylation. Down-regulation of ClC-3 protein by RNA interference as assessed by immunoblotting decreased the oxidation-stimulated permeability. In conclusion, oxidation induces surface expression of ClC-3 and activation of a ClC-3-dependent anion permeability in K562 cells.