The hydroxyphenylpyruvate dioxygenase from Synechocystis sp. PCC 6803 is not required for plastoquinone biosynthesis

Recently it has been reported that macrophages express a nuclear receptor, peroxisome proliferator-activated receptor γ (PPARγ). Using a ligand of PPARγ, troglitazone or pioglitazone, we have shown that the expression of two genes involved in cholesterol biosynthesis, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase and HMG-CoA reductase, were increased by activation of PPARγ through a PPAR response element (PPRE) in THP-1 macrophages. In addition, treatment with troglitazone significantly increased the activity of HMG-CoA reductase and the amount of intracellular cholesterol. Thus, we conclude that PPARγ and its agonists increase the cholesterol content of macrophages by the increased expression of genes involved in cholesterol biosynthesis. These findings suggest that PPARγ may play a role in cholesterol metabolism in macrophages.