Adiponutrin: A new gene regulated by energy balance in human adipose tissue

Adiponutrin is a newly identified nonsecreted adipocyte protein regulated by changes in energy balance in rodents. We documented the influence of energy balance modification on adiponutrin gene expression in humans. We investigated the mRNA expression in sc adipose tissue of nonobese women and in obese women during 2-d very low-calorie diet (VLCD) and subsequent refeeding as well as before and after a VLCD of 3 wk (21-d VLCD). The adiponutrin mRNA levels of the nonobese and obese women were not different (P > 0.05). Two-day VLCD reduced the average level of adiponutrin mRNA expression by 36% (P = 0.0016), whereas refeeding elevated the mRNA level by 31% (P = 0.004). The 3-wk VLCD caused a dramatic 58% fall of the adiponutrin mRNA expression level (P = 0.001). The mRNA level was negatively correlated with fasting glucose (Rho = -0.62; P < 0.0001), and subjects with high adiponutrin mRNA level had an increased insulin sensitivity. Compared with other adipocyte proteins such as leptin and adiponectin, adiponutrin mRNA did not show correlation with either adiposity indexes or with leptin or adiponectin mRNAs. These results indicate that adiponutrin gene expression in humans is highly regulated by changes in energy balance.