Adipose expression of catalase is regulated via a novel remote PPARgamma-responsive region

In adipose tissue of obese mice, the expression of catalase, an anti-oxidant enzyme, significantly decreases, which may cause insufficient elimination of hydrogen peroxide, but it does not in liver or skeletal muscle. However, the precise regulatory mechanism of catalase expression in adipocytes has not been fully defined. Here, we demonstrated that adipose tissues highly expressed catalase on the level comparable to liver and kidney, and treatment of mice with PPARgamma agonist significantly enhanced catalase expression in adipose tissue but not in liver. In 3T3-L1 cells, mRNA expression of catalase was up-regulated by the induction for adipose differentiation, and down-regulated by TNFalpha, in parallel with alterations in PPARgamma expression. PPARgamma agonist significantly enhanced catalase mRNA and activity. Furthermore, we newly identified a remote enhancer region containing two functional PPARgamma binding sites in mouse catalase gene. Collectively, our findings suggest that PPARgamma plays a crucial role in the expression of catalase in adipocytes.