Human aquaporin-11 is a water and glycerol channel and localizes in the vicinity of lipid droplets in human adipocytes

Objective: For a long time Aquaporin-7 has been the only Aquaporin associated with the adipose tissue, and its dysregulation has been linked to the underlying mechanisms of obesity. However, the presence of alternative glycerol channels within the adipose tissue has been postulated, which has prompted us to the search of alternate glycerol transport routes in adipocytes. In view of this, it is hypothesized that Aquaporin-11 (AQP11) would have a role in adipocyte Cell Biology.

Methods: The expression, the localization and the function of human AQP11 (hAQP11) in cultured differentiated adipocytes were investigated.

Results: Gene expression analysis revealed the presence of AQP11 in both subcutaneous and visceral human mature adipocytes. It is found that hAQP11 is primarily located intracellularly in human adipocytes and partially colocalizes with perilipin, pointing towards AQP11 preferential location in the vicinity of lipid droplets. Overexpression of hAQP11 in 3T3-L1 adipocytes enabled to validate its function as a water channel and reveal its glycerol permeation activity.

Conclusions: hAQP11 permeates both water and glycerol, localizing in the vicinity of lipid droplets in human adipocytes.