Role of aquaporin-7 and aquaporin-9 in glycerol metabolism; involvement in obesity.

The discovery of aquaporin (AQP) has had a great impact on life sciences. So far, 13 AQPs have been identified in human. AQP3, 7, 9, and 10 are subcategorized as aquaglyceroporins which permeabilize glycerol as well as water. Many investigators have demonstrated that AQPs play a crucial role in maintaining water homeostasis, but the physiological significance of some AQPs as a glycerol channel has not been fully understood. Adipocyte is considered to be a major source of glycerol which is one of substrates for hepatic gluconeogenesis. This review focuses on recent studies of glycerol metabolism through AQP7 and AQP9, and discusses the importance of glycerol channel in adipose tissues and liver.