Methionine sulfoxide suppresses adipogenic differentiation by regulating the mitogen-activated protein kinase signaling pathway.

In this study, methionine sulfoxide (MetO) was identified as an active metabolite that suppresses adipogenesis after screening obese individuals versus the normal population. MetO suppressed the gene and protein expression of CCAAT/enhancer binding protein (C/EBP) α, adipocyte fatty acid binding protein 4 (FABP4), and the nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) during human preadipocyte (HPA) differentiation. Adipogenesis decreased following MetO treatment; however, the preadipocyte number, proliferation, and apoptosis were unaffected. The activity of phosphorylated extracellular signal-related kinase (P-ERK) of the mitogen-activated protein kinase (MAPK) pathway was significantly inhibited in HPA after MetO treatment. Furthermore, treatment of preadipocytes with the selective P-ERK1/2 agonist Ro 67-7476 abolished the effect of MetO against adipogenesis suggesting that MetO function is dependent on the MAPK pathway. The mechanistic insights of adipogenesis suppression by MetO presented in this study shows its potential as an antiobesity drug.