A New Role for Aquaporin 7 in Insulin Secretion

作者：Louchami Karim; Best Len; Brown Peter; Virreira Myrna; Hupkens Emeline; Perret Jason; Devuyst Olivier; Uchida Shinichi; Delporte Christine; Malaisse Willy J; Beauwens Renaud; Sener Abdullah^*

来源：Cellular Physiology and Biochemistry, 2012, 29(1-2): 65-74.

DOI：10.1159/000337588

• AQP7
• Insulin-producing beta-cells
• Insulin secretion
• Cell swelling

Bacgrouns/Aims: Several insulinotropic agents were recently reported to cause beta-cell swelling. The possible participation of AQP7 to water transport was investigated in AQP7(+/+) or AQP7(-/-) mice. Methods: Aquaporin expression, insulin secretion, cell swelling and electrical activity were investigated in pancreatic islets. Results: RT-PCR revealed the expression of AQP5 and AQP8 mRNA. Double immunofluorescent labeling indicated their presence in beta-cells. Whilst basal insulin release from isolated pancreatic islets incubated at 2.8 mM D-glucose did not differ between AQP7(+/+) or AQP7(-/-) mice, the secretion of insulin evoked by the omission of 50 mM NaCl, the substitution of 50 mM NaCl by 100 mM glycerol or a rise in D-glucose concentration to 8.3 mM and 16.7 mM was severely impaired in the islets from AQP7(-/-) mice. Yet, exposure of beta-cells to either the hypotonic medium or a rise in D-glucose concentration caused a similar degree of swelling and comparable pattern of electrical activity in cells from AQP7(+/+) and AQP7(-/-) mice. Both the cell swelling and change in membrane potential were only impaired in AQP7(-/-) cells when exposed to 50 mM glycerol. Conclusion: It is proposed, therefore, that AQP7 may, directly or indirectly, play a role at a distal site in the exocytotic pathway.

• 出版日期2012