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 PPAR gamma 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 TNF alpha, in parallel with alterations in PPAR gamma expression. PPAR gamma agonist significantly enhanced catalase mRNA and activity. Furthermore, we newly identified a remote enhancer region containing two functional PPAR gamma binding sites in mouse catalase gene. Collectively, our findings suggest that PPAR gamma plays a crucial role in the expression of catalase in adipocytes. (c) 2007 Elsevier Inc. All rights reserved.