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Biochem Biophys Res Commun. 2005 Dec 23;338(3):1593-9. Epub 2005 Nov 2.

Effect on stability, degradation, expression, and targeting of aquaporin-2 water channel by hyperosmolality in renal epithelial cells.

Author information

1
Department of Medicine, University of Colorado Health Sciences Center, Denver, CO 80262, USA. Fuminori.Umenishi@UCHSC.edu

Abstract

To investigate the stability, degradation, expression, and targeting of aquaporin-2 (AQP2) by hyperosmolality, stably transfected mIMCD-3 cells expressing AQP2 (AQP2/IMCD3) were generated. In AQP2/IMCD3 cells, both nonglycosylated (ng-AQP2) and glycosylated (g-AQP2) forms were detected by immunoblot. The stability of ng-AQP2 decreased with the lapse of time, whereas that of g-AQP2 was stable. NaCl, but not urea, destabilized ng-AQP2. The half-life of ng-AQP2 in isotonic conditions was approximately 5 h, whereas that in medium supplemented with NaCl was approximately 1.5 h. Urea enhanced it compared to isotonic conditions. These findings indicate that the stability of ng-AQP2 is enhanced by urea, but not NaCl. The degradation of ng-AQP2 was dependent on proteasome and lysosome degradation pathways. The expression of ng-AQP2 was increased by hyperosmolality. Cell surface biotinylation experiments revealed that hyperosmolality enhanced the apical membrane insertion of ng-AQP2. These results indicate that hyperosmolality plays an important role in the stability, degradation, expression, and targeting of ng-AQP2.

PMID:
16288724
DOI:
10.1016/j.bbrc.2005.10.127
[Indexed for MEDLINE]

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