Osmolality and solute composition are strong regulators of AQP2 expression in renal principal cells

Item Type:	Article
Title:	Osmolality and solute composition are strong regulators of AQP2 expression in renal principal cells
Creators Name:	Storm, R. and Klussmann, E. and Geelhaar, A. and Rosenthal, W. and Maric, K.
Abstract:	The water permeability of the renal collecting duct is regulated by the insertion of aquaporin-2 (AQP2) into the apical plasma membrane of epithelial (principal) cells. Using primary cultured epithelial cells from the inner medulla of rat kidney (IMCD cells), we show that osmolality and solute composition are potent regulators of AQP2 mRNA and protein synthesis, as well as the classical cAMP-dependent pathway, but do not affect the arginine vasopressin-induced AQP2 shuttle. In the presence of the cAMP analog dibutyryl cAMP (DBcAMP, 500 microM), NaCl and sorbitol, but not urea, evoked a robust increase of AQP2 expression in IMCD cells, with NaCl being far more potent than sorbitol. cAMP-responsive element-binding protein phosphorylation increased with DBcAMP concentrations but was not altered by changes in osmolality. In the rat and human AQP2 promoter, we identified a putative tonicity-responsive element. We conclude that, in addition to the arginine vasopressin/cAMP-signaling cascade, a further pathway activated by elevated effective osmolality (tonicity) is crucial for the expression of AQP2 in IMCD cells, and we suggest that the effect is mediated via the tonicity-responsive element.
Keywords:	Osmolality, Aquaporin-2, Kidney, Gene regulation, Toxicity responsive, Animals, Rats
Source:	American Journal of Physiology Renal Physiology
ISSN:	0363-6127
Publisher:	American Physiological Society
Volume:	284
Number:	1
Page Range:	F189-F198
Date:	January 2003
Official Publication:	https://doi.org/10.1152/ajprenal.00245.2002
PubMed:	View item in PubMed

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