2,3,5-Tris(glutathion-S-yl)hydroquinone [TGHQ] is a potent nephrotoxicant and nephrocarcinogen, and induces a spectrum of mutations in human and bacterial cells consistent with those attributed to reactive oxygen species (ROS). Studies were conducted to determine whether the oxidative stress induced by TGHQ in renal proximal tubule epithelial cells (LLC-PK1) modulates transcriptional activities widely implicated in transformation responses, namely 12-O-tetradecanoyl phorbol 13-acetate (TPA) responsive element (TRE)- and nuclear factor kappa B (NF-κB)-binding activity. TGHQ increased TRE- and NF-κB-binding activity in a concentration- and time-dependent manner. Catalase fully inhibited peak TGHQ-mediated TRE- and NF-κB-binding activity. In contrast, although deferoxamine fully inhibited TGHQ-mediated TRE-binding activity, it had only a marginal effect on NF-κB-binding activity. Collectively, these data indicate that TGHQ modulates TRE- and NF-κB-binding activity in an ROS-dependent fashion. Cycloheximide and actinomycin D fully inhibited TGHQ-mediated TRE-binding activity, but in the absence of TGHQ increased NF-κB-binding activity. Although protein kinase C (PKC) is widely implicated in stress response signaling, pretreatment of cells with PKC inhibitors (H-89, calphostin C) did not modulate TGHQ-mediated DNA-binding activities. In contrast, pretreatment of cells with (PD098059), a mitogen activated protein kinase kinase (MEK) inhibitor, markedly reduced TGHQ-mediated TRE-binding activity, but enhanced TGHQ-mediated NF-κB-binding activity. We conclude that TGHQ-mediated TRE- and NF-κB-binding activities are ROS-dependent. Although there is a common requirement for hydrogen peroxide (H2O2) in the regulation of these DNA-binding activities, there appears to be divergent regulation after H2O2 generation in renal epithelial cells.
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