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Oxidative Stress Modulates KLF 6 Full and Its Splice Variants
Author(s) -
Urtasun Raquel,
Cubero Francisco Javier,
Nieto Natalia
Publication year - 2012
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.2012.01798.x
Subject(s) - menadione , reactive oxygen species , oxidative stress , chemistry , microbiology and biotechnology , paraquat , lipid peroxidation , biochemistry , biology
Background Induction of reactive oxygen species ( ROS ) is a central mechanism in alcohol hepatotoxicity. K rüppel‐like factor 6 ( KLF 6), a transcription factor and a tumor‐suppressor gene, is an early‐responsive gene to injury; however, the effect of ROS and alcohol on KLF 6 induction is unknown. The aim of this study is to investigate the contribution of 2 sources of ROS , cytochrome P 450 2 E 1 ( CYP 2 E 1), NAD(P)H quinone oxidoreductase ( NQO 1), and alcohol on the modulation of KLF6 Full expression, splicing to KLF6_V1 and KLF6_V2 , and the effect on TNF α, a downstream target. Methods and Results Endogenous ROS production in CYP2E1 ‐expressing HepG2 cells induced mRNA and protein expression of KLF6 Full and its splice variants compared to control cells. Incubation with pro‐oxidants such as arachidonic acid ( AA ), β‐naphtoflavone, and H 2 O 2 further enhanced KLF6 Full and its splice variants. The AA effects on KLF6 Full and its splice forms were blocked by vitamin E —which prevents lipid peroxidation—and by diallylsulfide—a CYP2E1 inhibitor. Menadione and paraquat, 2 pro‐oxidants metabolized via NQO1 , induced KLF6 Full mRNA in a thiol‐dependent manner. Antioxidants and an NQO1 inhibitor suppressed the menadione‐dependent increase in KLF6 Full and its splice variants mRNA . Furthermore, primary hepatocytes and livers from chronic alcohol‐fed rats, with elevated lipid peroxidation, H 2 O 2 and CYP2E1 but with low GSH , showed a ~2‐fold increase in KLF6 Full mRNA compared to controls. Inhibition of p38 phosphorylation further up‐regulated the CYP2E1 and the AA effects on KLF6 Full mRNA , whereas inhibition JNK and ERK1/2 phosphorylation decreased both. KLF6_V1 but not KLF6 Full ablation markedly increased TNFα levels in macrophages; thus, TNFα emerges as a downstream target of KLF6_V1 . Conclusions The novel effect of ROS on modulating KLF6 Full expression and its splice variants could play a relevant role in liver injury and in TNF α regulation.