title: Serine/threonine phosphatases and aquaporin-2 regulation in renal collecting duct.
abstract: Phosphorylation of the aquaporin-2 (AQP2) water channel at four COOH-terminal serines plays a central role in the regulation of water permeability of the renal collecting duct. The level of phosphorylation at these sites is determined by a balance between phosphorylation by protein kinases and dephosphorylation by phosphatases. The phosphatases that dephosphorylate AQP2 have not been identified. Here, we use large-scale data integration techniques to identify serine-threonine phosphatases likely to interact with AQP2 in renal collecting duct principal cells. As a first step, we have created a comprehensive list of 38 S/T phosphatase catalytic subunits present in the mammalian genome. Then we used Bayes' theorem to integrate available information from large-scale data sets from proteomic and transcriptomic studies to rank the known S/T phosphatases with regard to the likelihood that they interact with AQP2 in renal collecting duct cells. To broaden the analysis, we have generated new proteomic data (LC-MS/MS) identifying 4538 distinct proteins including 22 S/T phosphatases in cytoplasmic fractions from native inner medullary collecting duct cells from rats. The official gene symbols corresponding to the top-ranked phosphatases (common names in parentheses) were: Ppp1cb (PP1-β), Ppm1g (PP2C), Ppp1ca (PP1-α), Ppp3ca (PP2-B or calcineurin), Ppp2ca (PP2A-α), Ppp1cc (PP1-γ), Ppp2cb (PP2A-β), Ppp6c (PP6C), and Ppp5c (PP5). This ranking correlates well with results of prior reductionist studies of ion and water channels in renal collecting duct cells.
authors: Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and.|Howard University College of Medicine, Washington, District of Columbia.
authors: Sophia M
authors: SM
authors: LeMaire
authors: Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and.
authors: Viswanathan
authors: V
authors: Raghuram
authors: Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and.
authors: Cameron R
authors: CR
authors: Grady
authors: Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and.
authors: Christina M
authors: CM
authors: Pickering
authors: Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and.
authors: Chung-Lin
authors: CL
authors: Chou
authors: Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and.
authors: Ezigbobiara N
authors: EN
authors: Umejiego
authors: Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and knepperm@nhlbi.nih.gov.
authors: Mark A
authors: MA
authors: Knepper
mesh_terms: D000818:Animals; D051399:Aquaporin 2 / Q000378:metabolism*; D002853:Chromatography, Liquid / Q000379:methods; D006801:Humans; D007668:Kidney / Q000378:metabolism; D007685:Kidney Tubules, Collecting / Q000378:metabolism*; D051379:Mice; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D040901:Proteomics / Q000379:methods; D051381:Rats; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: C496023:AQP2 protein, human; C496024:Aqp2 protein, mouse; C496025:Aqp2 protein, rat; D051399:Aquaporin 2; D010749:Phosphoprotein Phosphatases
keywords: LC-MS/MS; collecting duct; kidney; systems biology; vasopressin