Context: Zinc-alpha2-glycoprotein (ZAG) was found to influence lipolysis in adipose tissue and has recently been proposed as a candidate factor in the regulation of body weight.
Objective: To elucidate the association of serum ZAG level with body weight and percentage of body fat in normal, obese subjects and high-fat diet (HFD)-induced obese mice.
Design: The relationship between serum ZAG and obesity-related parameters was studied in 44 human subjects and 36 mice fed standard food and HFD. Furthermore, the effects of ZAG overexpression on adipose tissue of mice was also evaluated by using a liposome transfection method.
Results: Serum ZAG level was significantly lower in obese patients and obese mice in comparison to that in people and mice with normal weight. The further statistical analysis demonstrated that ZAG level was negatively correlated with body weight (r=-0.62, P<0.001), body mass index (r=-0.64, P<0.001), waist circumference(r=-0.68, P<0.001), hip circumference (r=-0.60, P<0.001), percentage of body fat (r=-0.52, P=0.03) and fat mass(r=-0.59, P=0.01) in human subjects after adjustment for age and sex. Furthermore, ZAG overexpression in mice reduced body weight and the percentage of epididymal fat. The decreased FAS, ACC1 and DGAT mRNA and the increased HSL mRNA were also observed in epididymal adipose tissue in ZAG overexpression mice.
Conclusion: ZAG is closely linked to obesity. Serum ZAG level is inversely associated with body weight and percentage of body fat. The action of ZAG is associated with downregulated lipogenic enzymes and upregulated lipolytic enzyme expressions in adipose tissue of mice.