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A new role for aquaporin 7 in insulin secretion


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 (2012). A new role for aquaporin 7 in insulin secretion. Cellular Physiology and Biochemistry, 29(1-2):65-74.

Abstract

UNLABELLED: BACGROUNS/AIMS: Several insulinotropic agents were recently reported to cause β-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 β-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 β-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.

Abstract

UNLABELLED: BACGROUNS/AIMS: Several insulinotropic agents were recently reported to cause β-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 β-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 β-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.

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Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Nephrology
04 Faculty of Medicine > Institute of Physiology
07 Faculty of Science > Institute of Physiology

04 Faculty of Medicine > Center for Integrative Human Physiology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:2012
Deposited On:18 Jan 2013 12:29
Last Modified:28 Aug 2017 15:59
Publisher:Karger
ISSN:1015-8987
Additional Information:The final, published version of this article is available at http://www.karger.com/?doi=10.1159/000337588
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1159/000337588
PubMed ID:22415076

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