Aims/objectives: Glycerol cycling plays an essential regulatory role in metabolism in both health and disease. Aquaporins (AQPs) are a recently described family of water transporting membrane proteins, which contain a subset of members that also have the ability to transport glycerol across the cell membrane. This study sought to investigate the adipose tissue expression profile of AQPs in humans, and to assess the role of AQPs in adipocyte differentiation.
Methods: AQP expression was assessed in ex vivo human adipose tissue samples and isolated human adipocytes. Mouse 3T3L1 and human SGBS cells were also used for expression and differentiation studies. SYBR Green real-time PCR and Western Blotting were used to detect mRNA and protein expression respectively.
Results: AQP 3 and 7 were expressed in omental adipose tissue at a significantly higher level than in corresponding subcutaneous adipose tissue samples. AQP 7 was the most abundantly expressed aquaporin in both depots. In differentiating 3T3L1 adipocytes significant increases were seen in AQP 3 and 9 from day 0 to day 14, but not in AQP 7.
Conclusion/summary: AQP expression profiling in metabolic tissues is an important step in revealing the role they play in carbohydrate/lipid metabolism. We demonstrate here the differential expression of AQPs in omental and subcutaneous adipose tissue depots, and also report the changes in AQP expression in differentiating adipocytes, suggesting a role in lipid accumulation.