Soluble isocitrate dehydrogenase plays a key role in obesity and hyperlipidemia

NADPH is an essential co-factor for fat and cholesterol biosynthesis. However, the role of cytosolic NADP$\^$＋/-dependent isocitrate dehydrogenase (IDPc), a putative NADPH producer, in the control of the fat and cholesterol metabolism has not been assessed. Here we report that increased or decreased IDPc expression in 3T3-Ll fat cells promoted or retarded adipogenesis, respectively. Furthermore, overexpression of IDPc in transgenic mice exhibited fatty liver, hypertriglyceridemia, hypercholesterolemia and obesity by increasing NADPH production leading to subsequent stimulation of acetyl-coenzyme A and malonyl-coenzyme A consumption. In contrast, administrations of a synthetic IDPc inhibitor, DAl1004, to ob/ob mice effectively reduced body weight with lowering cholesterol and triglyceride levels. In addition, a positive relationship (${\gamma}$ = 0.69, $\rho$<0.0l) between plasma IDPc activity and body mass indexes was observed in 98 randomly-selected human volunteers. Our findings strongly indicate that NADPH produced by IDPc plays an important role in controlling body fat and lipid biosynthesis.