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Cyclic AMP is sufficient for triggering the exocytic recruitment of aquaporin-2 in renal epithelial cells

Item Type:Article
Title:Cyclic AMP is sufficient for triggering the exocytic recruitment of aquaporin-2 in renal epithelial cells
Creators Name:Lorenz, D. and Krylov, A. and Hahm, D. and Hagen, V. and Rosenthal, W. and Pohl, P. and Maric, K.
Abstract:The initial response of renal epithelial cells to the antidiuretic hormone arginine vasopressin (AVP) is an increase in cyclic AMP. By applying immunofluorescence, cell membrane capacitance and transepithelial water flux measurements we show that cAMP alone is sufficient to elicit the antidiuretic cellular response in primary cultured epithelial cells from renal inner medulla, namely the transport of aquaporin-2 (AQP2)-bearing vesicles to, and their subsequent fusion with, the plasma membrane (AQP2 shuttle). The AQP2 shuttle is evoked neither by AVP-independent Ca(2+) increases nor by AVP-induced Ca(2+) increases. However, clamping cytosolic Ca(2+) concentrations below resting levels at 25 nM inhibited exocytosis. Exocytosis was confined to a slow monophasic response, and readily releasable vesicles were missing. Analysis of endocytic capacitance steps revealed that cAMP does not decelerate the retrieval of AQP2 from the plasma membrane. Our data suggest that cAMP initiates an early step, namely the transport of AQP2-bearing vesicles towards the plasma membrane, and do not support a regulatory function for Ca(2+) in the AQP2 shuttle.
Keywords:Aquaporins, Arginine Vasopressin, Calcium Signaling, Cell Line, Cyclic AMP, Endocytosis, Epithelial Cells, Exocytosis, Immunohistochemistry, Kidney Medulla, Collecting Kidney Tubules, Photolysis, Protein Transport, Second Messenger Systems, Animals, Rats
Source:EMBO Reports
Publisher:Nature Publishing Group
Page Range:88-93
Date:January 2003
Official Publication:https://doi.org/10.1038/sj.embor.embor711
PubMed:View item in PubMed

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