UCP1 and obesity due to melanocortin 4 receptor deficiency: Irisin expression is regulatedby peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α.PGC-1α regulates uncoupling protein (UCP)-1 expression to promotethermogenesis in brown adipose tissue.13−15 UCP-1 expression islower in white adipose tissue, which possess the ability to serveas a possible target for obesity treatment.16 Previous studies have shown that brown adipose tissue positivelyaffects metabolism and energy balance in mice.