DNMT1 and obesity due to melanocortin 4 receptor deficiency: Over-expression of Dnmt1 in 3T3-L1 adipocytes increases methylation and decreases expression of Adipoq, while its knockdown results in the reverse (Kim et al., 2015), suggesting that direct hypermethylation and heterochromatin formation by DNMT1 at the Adipoq gene promoter is involved in obesity pathogenesis.