RT Journal Article T1 Melatonin induces fat browning by transdifferentiation of white adipocytes and de novo differentiation of mesenchymal stem cells. A1 Salagre, Diego A1 Chayah, Meriem A1 Molina-Carballo, Antonio A1 Oliveras-López, María-Jesús A1 Munoz-Hoyos, Antonio A1 Navarro-Alarcón, Miguel A1 Fernández-Vázquez, Gumersindo A1 Agil, Ahmad AB The role of melatonin in obesity control is extensively accepted, but its mechanism of action is still unclear. Previously we demonstrated that chronic oral melatonin acts as a brown-fat inducer, driving subcutaneous white adipose tissue (sWAT) into a brown-fat-like function (beige) in obese diabetic rats. However, immunofluorescence characterization of beige depots in sWAT and whether melatonin is a beige-fat inducer by de novo differentiation and/or transdifferentiation of white adipocytes are still undefined. Lean (ZL) and diabetic fatty (ZDF) Zücker rats were subdivided into two groups, control (C) and oral melatonin-supplemented (M, 10 mg kg-1 day-1) for 6 weeks. Mesenchymal stem cells (MSCs) were isolated from both rat inguinal fat and human lipoaspirates followed by adipogenesis assays with or without melatonin (50 nM for 12 h in a 24 h period, 12 h+/12 h-) mimicking the light/dark cycle. Immunofluorescence and western-blot assays showed the partial transdifferentiation of white adipocytes in both ZL and ZDF rats, with increasing thermogenic and beige markers, UCP1 and CITED1 and decreasing white adipocyte marker ASC-1 expression. In addition, melatonin increased UCP1, CITED1, and PGC1-α expression in differentiated adipocytes in both rats and humans. These results demonstrate that melatonin increases brown fat in obese diabetic rats by both adipocyte transdifferentiation and de novo differentiation. Furthermore, it promotes beige MSC adipogenesis in humans. This may contribute to the control of body weight attributed to melatonin and its metabolic benefits in human diabesity. YR 2022 FD 2022-03-21 LK http://hdl.handle.net/10668/19640 UL http://hdl.handle.net/10668/19640 LA en DS RISalud RD Apr 10, 2025