MYF5 and obesity due to melanocortin 4 receptor deficiency: To determine the role of brown fat Dnmt3b in the regulation of diet-induced obesity, we generated a genetic model with deletion of Dnmt3b in brown fat-skeletal muscle lineage precursor cells (3bKO) by crossing Dnmt3b-floxed (fl/fl) mice with Myf5-cre mice.