Direct conversion of human myoblasts into brown-like adipocytes by engineered superactive PPARγ

OBJECTIVE: To determine whether super-activation of PPARγ can reprogram human myoblasts into brownlike adipocytes and to establish a new cell model for browning research. METHODS: To enhance the PPARγ signaling, we fused M3, the transactivation domain of MyoD, to PPARγ. PPARγ and M3-PPARγ-lentiviral vectors were used to convert human myoblasts into adipocytes. Brown adipocyte markers of the reprogrammed adipocytes were assessed by qPCR and protein analyses. White adipocytes differentiated from subcutaneous stromal vascular cells and perithyroid brown fat tissues were used as references. RESULTS: In transient transfection, M3-PPARγ has stronger constitutive activity than PPARγ reporter assay. Although both the transduction of PPARγ and M3-PPARγ induced adipogenesis in myoblasts, M3-PPARγ, compared to PPARγ, drastically induced the brown adipocyte markers of UCP1, CIDEA and PRDM16 by 1,050, 2.4, and 5.0 fold, respectively and increased mitochondria contents by 4 fold. The gene expression levels of the browning makers in PPARγ-reprogrammed adipocytes are comparable to those of in vitro differentiated white adipocytes. CONCLUSIONS: We have found that super-activation of PPARγ can effectively convert human myoblasts into brown-like adipocytes and can be a new approach to derive brown-like adipocytes.