Zinc-α2-glycoprotein: an adipokine modulator of body fat mass?

Abstract

The importance of white adipose tissue in the control of energy balance is now firmly recognized. In addition to fuel storage, adipocytes secrete an array of proteins factors (adipokines), which regulate multiple physiological and metabolic processes as well as influence body fat accumulation. Zinc-a2-glycoprotein (ZAG), a lipid mobilizing factor initially characterized as a tumor product associated with cachexia, has recently been identified as a novel adipokine. Although the exact role of ZAG in adipose tissue remains to be clarified, there is evidence that ZAG expression appears to be inversely related to adiposity, being upregulated in cachexia whereas reduced in obesity. Investigations on the regulation of ZAG give insights into its potential function in adipose tissue with a link to lipid mobilization and an anti-inflammatory action. Recent work shows that ZAG stimulates adiponectin secretion by human adipocytes. Data from genetic studies suggest that ZAG may be a candidate gene for body weight regulation; this is supported by the demonstration that ZAG-knockout mice are susceptible to weight gain, whereas transgenic mice overexpressing ZAG exhibit weight loss. The present review summarizes these new perspectives of ZAG and the potential mechanisms by which it might modulate adipose tissue mass and function.

rs4215 SNP in zinc-α2-glycoprotein gene is associated with obesity in Chinese north Han population

“…Further analysis found the subjects with GG genotype have much higher body weight, BMI, waist circumference and SBP in comparison with the subjects with AA genotype. All of these findings together with our previous in vivo studies (Bing et al, 2010;Gong et al, 2009;Gong et al, 2010), which demonstrated serum ZAG level is negatively correlated with body weight, BMI, fat mass and waist circumference, and that administration of high-fat-diet induced obese mice with ZAG would result in a great reduction in body weight and body fat, imply that ZAG is an important regulatory factor of body weight and plays a crucial role during the occurrence and development of obesity (Bing et al, 2010). About the gender specific association in rs4215 site in the ZAG gene with obesity, one possible explanation is as follows.…”

“…Although the pathogenesis of obesity and its associated co-morbidities are multifactorial, growing evidence suggests that altered production of adipose-derived protein factors (adipocytokines), such as leptin, adiponectin and tumor necrosis factor-α (TNF-α), plays an important role in the occurrence and development of obesity (Bing et al, 2010). ZAG has been identified recently as such a novel adipokine due to its close link to lipid, glucose metabolism, its crucial role in regulation of body weight and fat mass, as well as its significant antiobesity and antidiabetic effects in rat and ob/ob mice Tisdale, 2010b, 2011).…”

A Form of Apolipoprotein A-I Is Found Specifically in Relapses of Focal Segmental Glomerulosclerosis Following Transplantation

“…ZAG is involved in lipid mobilization (14). It is elevated in urine during energy-demanding conditions (15), but decreases in acute kidney injury (16).…”

Ovarian, metabolic and endocrine indexes in dairy cows with different body condition scores

“…Here we demonstrate the association between the level of endogenous Zn 2+ (but not other microelements) and bovine ovarian functions: BCS2 cows had higher blood Zn 2+ levels, lower ovarian, follicular and corpora albicantia size in comparison with the BCS3 animals, while granulosa cells isolated from the ovaries of the former released more oestradiol than those obtained from the BCS3 group. Zn 2+ has been shown to be stimulator of appetite (Suzuki et al, 2011) and adipose tissue development (Bing et al, 2010). Therefore, an increased plasma Zn 2+ level in cows with a tendency towards emaciation might be a promoter of bovine appetite, fat gain, and return to average BCS.…”