PPARG and obesity due to melanocortin 4 receptor deficiency: First, peroxisome proliferator-activated receptor-γ (PPAR-γ) expressed by Treg cells is necessary for the accumulation, phenotype, and function of VAT Treg cells in lean mice through collaborating with Foxp3 to induce a distinct Treg signature; while obesity induces the disappearance of this VAT Treg signature by phosphorylation of PPAR-γ at position Ser273 (42–44).