UCP1 and obesity due to melanocortin 4 receptor deficiency: Our data showed that the IRF4 promoter, rather than the PGC-1α promoter, can be driven directly by DHM, suggesting that DHM may induce the expression of IRF4; this IRF4 can promote the expression of PGC-1α and physically interact with PGC-1α to increase UCP1 expression, thereby playing a role in improving obesity.