The formation of brown adipose tissue induced by transgenic over-expression of PPARγ2

Brown adipose tissue (BAT) is specialized to dissipate energy as heat, therefore reducing fat deposition and counteracting obesity. Brown adipocytes arise from myoblastic progenitors during embryonic development by the action of transcription regulator PRDM16 binding to PPAR gamma, which promotes BAT-like phenotype in white adipose tissue. To investigate the capability of converting white adipose tissue to BAT or browning by PPAR gamma in vivo, we generated transgenic mice with over-expressed PPAR gamma 2. The transgenic mice showed strong brown fat features in subcutaneous fat in morphology and histology. To provide molecular evidences on browning characteristics of the adipose tissue, we employed quantitative real-time PCR to determine BAT-specific gene expressions. The transgenic mice had remarkably elevated mRNA level of UCP1, ElovI3, PGC1 alpha and Cebp alpha in subcutaneous fat. Compared with wild-type mice, UCP1 protein levels were increased significantly in transgenic mice. ATP concentration was slightly decreased in the subcutaneous fat of transgenic mice. Western blotting analysis also confirmed that phosphorylated AMPK and ACC proteins were significantly (P < 0.01) increased in the transgenic mice. Therefore, this study demonstrated that over-expression of PPAR gamma 2 in skeletal muscle can promote conversion of subcutaneous fat to brown fat formation, which can have beneficial effects on increasing energy metabolisms and combating obesity. (C) 2014 Elsevier Inc. All rights reserved.