Protein kinase A anchoring proteins are required for vasopressin-mediated translocation of aquaporin-2 into cell membranes of renal principal cells.
The antidiuretic hormone arginine-vasopressin (AVP) regulates water reabsorption in renal collecting duct principal cells by inducing a cAMP-dependent translocation of water channels (aquaporin-2, AQP-2) from intracellular vesicles into the apical cell membranes. In subcellular fractions from primary cultured rat inner medullary collecting duct (IMCD) cells, enriched for intracellular AQP-2-bearing vesicles, catalytic protein kinase A (PKA) subunits and several protein kinase A anchoring proteins (AKAPs) were detected. In nonstimulated IMCD cells the majority of AQP-2 staining was detected intracellularly but became mainly localized within the cell membrane after stimulation with AVP or forskolin. Quantitative analysis revealed that preincubation of the cells with the synthetic peptide S-Ht31, which prevents the binding between AKAPs and regulatory subunits of PKA, strongly inhibited AQP-2 translocation in response to forskolin. Preincubation of the cells with the PKA inhibitor H89 prior to forskolin stimulation abolished AQP-2 translocation. In contrast to H89, S-Ht31 did not affect the catalytic activity of PKA. These data demonstrate that not only the activity of PKA, but also its tethering to subcellular compartments, are prerequisites for cAMP-dependent AQP-2 translocation.
Klussmann
E
E
Forschungsinstitut für Molekulare Pharmakologie, Alfred-Kowalke-Strasse 4, D-10315 Berlin, Germany. klussmann@fmp-berlin.de
Maric
K
K
Wiesner
B
B
Beyermann
M
M
Rosenthal
W
W
D000818:Animals; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins / Q000378:metabolism*; D001127:Arginine Vasopressin / Q000494:pharmacology*; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D020134:Catalytic Domain; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats