Jiao Yang, Zhang Jingying, Lu Lunjie, Xu Jiaying, Qin Liqiang
Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Medical College of Soochow University, Suzhou 215123, China.
Department of Radiation Genetics, School of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou 215123, China.
Nutrients. 2016 Feb 19;8(2):102. doi: 10.3390/nu8020102.
The highly regulated differentiation and proliferation of pre-adipocytes play a key role in the initiation of obesity. Fat mass and obesity associated (FTO) is a novel gene strongly associated with the risk of obesity. A deficiency of FTO may cause growth retardation in addition to fat mass and adipocyte size reduction in vivo. To investigate the potential role of Fto gene on the proliferation and differentiation of pre-adipocytes, we generated Fto-knockdown and overexpressed 3T3-L1 cells. Using numerous proliferation assays our results suggest that Fto knockdown leads to suppression of proliferation, lower mitochondrial membrane potential, less cellular ATP, and decreased and smaller intracellular lipid droplets compared with controls (p < 0.05). Western blot analysis demonstrated that Fto knockdown can significantly suppress peroxisome proliferator-activated receptor gamma (PPARγ) and glucose transporter type 4 (GLUT4) expression and inhibit Akt phosphorylation. By contrast, overexpression of Fto had the opposing effect on proliferation, mitochondrial membrane potential, ATP generation, in vitro differentiation, Akt phosphorylation, and PPARγ and GLUT4 expression. Moreover, we demonstrated that Wortmannin, a phosphoinositide 3-kinase (PI3K) inhibitor, could inhibit phospho-Akt in Fto overexpressed 3T3-L1 cells. Taken together, the results suggest that Fto regulates the proliferation and differentiation of 3T3-L1 cells via multiple mechanisms, including PPARγ and PI3K/Akt signaling.
前脂肪细胞高度有序的分化和增殖在肥胖症的发生中起关键作用。脂肪量和肥胖相关基因（FTO）是一种与肥胖风险密切相关的新基因。FTO缺乏除了会导致体内脂肪量和脂肪细胞大小减少外，还可能引起生长发育迟缓。为了研究Fto基因在前脂肪细胞增殖和分化中的潜在作用，我们构建了Fto基因敲低和过表达的3T3-L1细胞。通过多种增殖实验，我们的结果表明，与对照组相比，Fto基因敲低导致细胞增殖受抑、线粒体膜电位降低、细胞内ATP减少以及细胞内脂滴数量减少且体积变小（p < 0.05）。蛋白质免疫印迹分析表明，Fto基因敲低可显著抑制过氧化物酶体增殖物激活受体γ（PPARγ）和葡萄糖转运蛋白4（GLUT4）的表达，并抑制Akt磷酸化。相反，Fto过表达对细胞增殖、线粒体膜电位、ATP生成、体外分化、Akt磷酸化以及PPARγ和GLUT4表达具有相反的作用。此外，我们证明，磷脂酰肌醇3激酶（PI3K）抑制剂渥曼青霉素可抑制Fto过表达的3T3-L1细胞中的磷酸化Akt。综上所述，结果表明Fto通过多种机制调节3T3-L1细胞的增殖和分化，包括PPARγ和PI3K/Akt信号通路。
