Oxidative stress activates anion exchange protein 2 and AP-1 in airway epithelial cells

Abstract

Anion exchange protein 2 (AE2) is a membrane-bound protein that mediates chloride-bicarbonate exchange. In addition to regulating intracellular pH and cell volume, AE2 exports superoxide (O[Formula: see text]·) to the extracellular matrix in an HCO[Formula: see text]-dependent process. Given this ability to export O[Formula: see text]·, we hypothesized that expression of AE2 in the lung is regulated by oxidative stress. AE2 mRNA and protein expression was measured by RT-PCR and Western blot analysis, respectively, in differentiated human bronchial epithelial cells exposed to H 2 O 2(100 μM). Alterations in in vivo AE2 protein expression were evaluated in lung tissue of rats exposed to 70% O 2. The role of transcription factor activator protein (AP)-1 in oxidant regulation of AE2 was evaluated by EMSA and by immunoblotting of nuclear phospho-c- jun. Results show increased AE2 mRNA and protein expression after oxidant exposure. This was preceded by transient increases in DNA binding of AE2-specific AP-1 and phosphorylation of c- jun. This study demonstrates that AE2 expression is regulated by oxidative stress in airway epithelial cells and that this regulation correlates with activation of AP-1.