Remodeling of energy-storing white fat into energy-consuming beige fat has led to a promising new approach to alleviate adiposity. Several studies have shown adipokines can induce white adipose tissue (WAT) beiging through autocrine or paracrine actions. Betatrophin, a novel adipokine, has been linked to energy expenditure and lipolysis but not clearly clarified. Here, we using high-fat diet-induced obesity to determine how betatrophin modulate beiging and adiposity. We found that betatrophin-knockdown mice displayed less white fat mass and decreased plasma TG and NEFA levels. Consistently, inhibition of betatrophin leads to the phenotype change of adipocytes characterized by increased mitochondria contents, beige adipocytes and mitochondria biogenesis-specific markers both in vivo and in vitro. Of note, blocking AMP-activated protein kinase (AMPK) signaling pathway is able to abolish enhanced beige-like characteristics in betatrophin-knockdown adipocytes. Collectively, downregulation of betatrophin induces beiging in white adipocytes through activation of AMPK signaling pathway. These processes suggest betatrophin as a latent therapeutic target for obesity.
Zhe-Zhen Liao, Xiao-Yan Qi, Ya-Di Wang, Jiao-Yang Li, Qian-Qian Gu, Can Hu, Yin Hu, Heng Sun, Li Ran, Jing Yang, Jiang-Hua Liu and Xin-Hua Xiao
Li Zhao, Chunfang Zhu, Meng Lu, Chi Chen, Xiaomin Nie, Buatikamu Abudukerimu, Kun Zhang, Zhiyuan Ning, Yi Chen, Jing Cheng, Fangzhen Xia, Ningjian Wang, Michael D Jensen and Yingli Lu
Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are an ideal therapy for type 2 diabetes and, as of recently, for obesity. In contrast to visceral fat, subcutaneous fat appears to be protective against metabolic diseases. Here, we aimed to explore whether liraglutide, a GLP-1RA, could redistribute body fat via regulating lipid metabolism in different fat depots. After being fed a high-fat diet for 8 weeks, 50 male Wistar and Goto-Kakizaki rats were randomly divided into a normal control group, a diabetic control group, low- and high-dose liraglutide-treated groups and a diet-control group. Different doses of liraglutide (400 μg/kg/day or 1200 μg/kg/day) or an equal volume of normal saline were administered to the rats subcutaneously once a day for 12 weeks. Body composition and body fat deposition were measured by dual-energy X-ray absorptiometry and MRI. Isotope tracers were infused to explore lipid metabolism in different fat depots. Quantitative real-time PCR and Western blot analyses were conducted to evaluate the expression of adipose-related genes. The results showed that liraglutide decreased visceral fat and relatively increased subcutaneous fat. Lipogenesis was reduced in visceral white adipose tissue (WAT) but was elevated in subcutaneous WAT. Lipolysis was also attenuated, and fatty acid oxidation was enhanced. The mRNA expression levels of adipose-related genes in different tissues displayed similar trends after liraglutide treatment. In addition, the expression of browning-related genes was upregulated in subcutaneous WAT. Taken together, the results suggested that liraglutide potentially redistributes body fat and promotes browning remodeling in subcutaneous WAT to improve metabolic disorders.