Exploration Of Target Genes At Tissue Level For Zinc-α2-glycoprotein To Reduce Body Weight And Improve Insulin Sensitivity

Objective:To explore the potential target gene of ZAG that contribute to the anti-obesity and anti-diabetic effect of ZAG in high-fat diet (HFD) induced obese mice.Methods:Male ICR mice were fed with HFD for8weeks to establish obese mice model. HFD induced obese mice were treated with ZAG for another8weeks. At the end of intervention, intraperitoneal glucose tolerance test (IPGTT), insulin tolerance test (ITT) and microPET imaging were performed, blood biochemistry parameters were determined, subcutaneous and visceral adipose tissue mass were weighted, and expression of genes related to lipid and glucose metabolism was evaluated by real-ime polymerase chain reaction (RT-qPCR) and chip assays.Results:The difference in body weight between mice fed with HFD (54.30±1.53g) and standard food (SF)(3.87±1.14g) was statistically significant (P<0.001) after8weeks. Body weight of mice fed with HFD was1.24-fold of that in mice fed with SF, indicating obese mice model was established successfully.8weeks after ZAG intervention, body weight of obese mice in ZAG group was significantly lower than that in HFD control group (48.5±3.4g vs56.7±2.2g, P<0.05), as well as subcutaneous adipose tissue mass, which was significantly decreased (P<0.01) by57%. In addition, weights of visceral adipose tissue, including mesenteric, perirenal and epididymal adipose tissue in ZAG group were also significantly (All P value less than0.05) decreased(by56%,43%and74%, respectively). Glucose levels at0,30,90,120minutes in ITT, as well as glucose levels at60,90,120in IPGTT were significantly lower in ZAG treated mice when compared with that in HFD mice (All P value lower0.05). Both the area under curve (AUC) of glucose in ITT and AUC of glucose in IPGTT were reduced in ZAG group (All P value lower0.05).Blood biochemistry test revealed serum levels of FFA was significantly (P<0.05) higher in ZAG group (1541.88±98.21μmol/L) than that in HFD control group (1129.85±82.66μmol·L). Further gene expression analysis at tissue level found the long-chain-fatty-acid—CoA ligase1(ACSL1) expression in liver in ZAG group was reduced to35～60%of that in HFD control. Besides, expression of Peroxisome proliferator-activated receptor gamma coactivator lalpha (PGC1α), a gene involved in the regulation of fatty acid oxidation and mitochondrial thermogenesis, was significantly (All P value lower0.05) lower (44%and17%of that in SF group, respectively) in white adipose tissue and liver in HFD group than that in SF group, whereas PGC1α expression in white adipose tissue and liver in ZAG treated mice was increased (1.19-fold and2.49-fold, respectively) significantly (All P value lower0.05), when compared to HFD group. Further analysis revealed a strong positive correlation (Correlation coefficiency=0.775, P<0.01) between expression levels of ZAG and expression levels of PGC1α in subcutaneous adipose tissue.Conclusions:ZAG can reduce body weight, decrease subcutaneous and visceral white adipose tissue mass, improve glucose metabolism and increase whole body insulin sensitivity in HFD-induced obese mice. The beneficial effect of ZAG on glucose and lipid metabolism was realized through inhibiting lipogenesis, promoting lipolysis and energy expenditure. PGC1α was a possible target gene of ZAG, that contribute to the actions of ZAG in obese mice.