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FDA‐Approved PDE4 Inhibitor Roflumilast Enhances Vasopressin‐Induced Aquaporin‐2 Phosphorylation Changes in Renal Collecting Duct
Author(s) -
Umejiego E.,
Chou CL,
Knepper M.A.
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.809.20
Subject(s) - phosphorylation , aquaporin 2 , roflumilast , chemistry , vasopressin , phosphodiesterase inhibitor , medicine , phosphodiesterase , endocrinology , protein phosphorylation , pharmacology , protein kinase a , biochemistry , enzyme , mechanical engineering , copd , water channel , engineering , inlet
Vasopressin (AVP)‐regulated water permeability increases in renal collecting duct are mediated by intracellular cyclic AMP. Previous mass spectrometry studies have shown that AVP increases the protein phosphorylation of aquaporin‐2 water channel protein (AQP2) at Ser256, Ser264, Ser269 and decreases phosphorylation at Ser261. Proteomic profiling of inner medullary collecting duct (IMCD) has also shown that phosphodiesterase 4 (PDE4) is a predominant isoform of cyclic nucleotide phosphodiesterase. The present study sought to determine the effect of roflumilast, an FDA‐approved phosphodiesterase 4 (PDE4) inhibitor, on AQP2 phosphorylation in rat IMCD. Phosphorylation of AQP2 on all four serine residues was determined by immunoblotting using phospho‐specific antibodies. When IMCD suspensions were treated with 30 nM roflumilast in the absence of V2‐receptor agonist dDAVP, there was no change in AQP2 phosphorylation on the four sites versus vehicle‐treated IMCDs. However, when IMCD suspensions were treated with roflumilast in the presence of 0.1 nM dDAVP, there was a demonstrable increase in pS256 (33 ± 4%), pS264 (116 ± 46%), pS269 (605 ± 340%) and a decrease in pS261 (23 ± 7%) in comparison to IMCD treated with dDAVP alone (n=3). Similar results were obtained with roflumilast‐N‐oxide, an active metabolite of roflumilast. These results suggest that the PDE4 inhibitor roflumilast can be used to enhance vasopressin's action on AQP2 phosphorylation.