Gender-specific effect of physical training on AQP7 protein expression in human adipose tissue

AQP7 is a glycerol channel in adipose tissue with a suggested role in controlling the accumulation of triglycerides and secondly development of obesity and type-2 diabetes. In the present study, we aimed to test the hypotheses that (1) AQP7 is localized to the capillaries within human adipose tissue, (2) genetic predisposition to type-2 diabetes is associated with a low expression of AQP7 in abdominal subcutaneous adipose tissue (SAT) and (3) physical training increases AQP7 expression in SAT. The cellular localization of AQP7 in adipose tissue was investigated by immunohistochemistry. The relative expression of AQP7 protein in abdominal SAT was analysed before and after ending a 10-week exercise training programme in first-degree relatives to type-2 diabetic patients and control individuals. Non-obese first-degree relatives to type-2 diabetic patients (n = 20) and control (n = 11) men and women participated in this study. By this, we find that AQP7 is localized to the capillary endothelial cells within adipose tissue. We were unable to evidence a link between a low AQP7 abundance in SAT and genetic predisposition type-2 diabetes. Instead we demonstrate that physical training influences the expression of AQP7 in SAT in a gender-specific manner. Thus, women responds by increasing the abundance of AQP7 by 2.2-fold (p = 0.03) whereas in men a reduced expression is observed (p = 0.00009), resulting in a more than twofold higher abundance of AQP7 in women as compared with men. In conclusion, the adipose tissue glycerol channel, AQP7, is regulated in response to physical training in a gender-dependent manner in SAT.