Aquaporin-2: COOH terminus is necessary but not sufficient for routing to the apical membrane

Deen, Peter M.T.; Balkom, Bas W. M. van; Savelkoul, Paul J.M.; Kamsteeg, Erik‐Jan; Raak, M. van; Jennings, Michael L.; Muth, Theodoor R.; Rajendran, V.; Caplan, Michael J.

doi:10.1152/ajprenal.0168.2001

Cited by 49 publications

(67 citation statements)

References 45 publications

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“…We were able to detect phosphorylation of AQP2 at S256, a site in the C terminus previously shown to be important for vasopressinstimulated trafficking to the apical plasma membrane (13,(18)(19)(20). In addition, three other sites in the C-terminal tail of AQP2 were also found to be phosphorylated: S261, S264, and S269.…”

Section: Discussionmentioning

confidence: 70%

Quantitative phosphoproteomics of vasopressin-sensitive renal cells: Regulation of aquaporin-2 phosphorylation at two sites

Hoffert

Pisitkun

Wang

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

327

325

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Protein phosphorylation plays a key role in vasopressin signaling in the renal-collecting duct. Large-scale identification and quantification of phosphorylation events triggered by vasopressin is desirable to gain a comprehensive systems-level understanding of this process. We carried out phosphoproteomic analysis of rat inner medullary collecting duct cells by using a combination of phosphopeptide enrichment by immobilized metal affinity chromatography and phosphorylation site identification by liquid chromatography-mass spectrometry n neutral loss scanning. A total of 714 phosphorylation sites on 223 unique phosphoproteins were identified from inner medullary collecting duct samples treated shortterm with either calyculin A or vasopressin. A number of proteins involved in cytoskeletal reorganization, vesicle trafficking, and transcriptional regulation were identified. Previously unidentified phosphorylation sites were found for membrane proteins essential to collecting duct physiology, including eight sites among aquaporin-2 (AQP2), aquaporin-4, and urea transporter isoforms A1 and A3. Through label-free quantification of phosphopeptides, we identified a number of proteins that significantly changed phosphorylation state in response to short-term vasopressin treatment: AQP2, Bclaf1, LRRC47, Rgl3, and SAFB2. In the presence of vasopressin, AQP2 monophosphorylated at S256 and diphosphorylated AQP2 (pS256͞261) increased in abundance, whereas AQP2 monophosphorylated at S261 decreased, raising the possibility that both sites are involved in vasopressin-dependent AQP2 trafficking. This study reveals the practicality of liquid chromotography-mass spectrometry n neutral loss scanning for large-scale identification and quantification of protein phosphorylation in the analysis of cell signaling in a native mammalian system. LC-MS͞MS ͉ collecting duct ͉ kidney ͉ Collecting Duct Phosphoprotein Database (CDPD) ͉ neutral loss E lucidation of cellular signaling networks requires methodologies for large-scale quantitative phosphoproteomic analysis that can be used to reveal dynamic system-wide changes in protein phosphorylation. Recent studies have introduced two new innovations, namely, immobilized metal affinity chromatography (IMAC) (1-3) and liquid chromatography-mass spectrometry (LC-MS) 3 neutral loss scanning (1-4), to increase the efficiency of phosphopeptide identification. Quantification of phosphopeptides in this setting has been challenging and has been successful so far in cultured cells (5) and yeast (6) but not in native mammalian cells and tissues. Here, we introduce a hybrid approach using IMAC for phosphopeptide enrichment, LC-MS multisequential (LC-MS n ) neutral loss scanning to identify phosphorylated residues in the peptides, and label-free quantification using numerical integration of pseudochromatograms constructed from MS peak heights.The method is used here for analysis of protein phosphorylation in vasopressin-sensitive inner medullary collecting duct (IMCD) cells freshly isolated from rat kidneys. ...

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Section: Discussionmentioning

confidence: 70%

Quantitative phosphoproteomics of vasopressin-sensitive renal cells: Regulation of aquaporin-2 phosphorylation at two sites

Hoffert

Pisitkun

Wang

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

327

325

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“…Proteins were visualized using ECL (Pierce, Rockford, IL). Immunocytochemistry was done as described previously (24). Data are based on at least two independent experiments in which triplicates per condition were taken.…”

Section: Immunoblotting and Immunocytochemistrymentioning

confidence: 99%

Development of Lithium-Induced Nephrogenic Diabetes Insipidus Is Dissociated from Adenylyl Cyclase Activity

Li¹,

Shaw²,

Kamsteeg³

et al. 2006

Journal of the American Society of Nephrology

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100

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In antidiuresis, vasopressin (AVP) occupation of V2 receptors in renal collecting ducts activates adenylyl cyclase, resulting in increased intracellular cAMP levels, which activates protein kinase A (PKA). PKA phosphorylates both the cAMP responsive element binding protein, which induces aquaporin-2 (AQP2) transcription, and AQP2, which then is translocated to the apical membrane, allowing urine concentration. Lithium treatment often causes nephrogenic diabetes insipidus (NDI), which coincides with decreased AQP2 expression and which generally is ascribed to reduced adenylyl cyclase activity. However, the underlying mechanism by which lithium causes NDI is poorly understood. This study demonstrated that the mouse cortical collecting duct mpkCCD c14 cells are a good model; the deamino-8 D-arginine vasopressin (dDAVP)-induced endogenous AQP2 expression and plasma membrane localization was time-dependently reduced by treatment with clinically relevant lithium concentrations. Lithium did not affect AQP2 stability but decreased its mRNA levels. Surprising, the effect of lithium was cAMP independent; it did not alter AVP-stimulated cAMP production or PKA-dependent phosphorylation of AQP2 or cAMP responsive element binding protein. In vivo, kidney tissue of rats with lithium-induced NDI indeed generated less dDAVP-induced cAMP than that of controls, but this could be due to elevated blood AVP levels in rats with lithium-induced NDI. Indeed, Brattleboro rats, which lack endogenous AVP, with clamped blood dDAVP levels, showed no difference in dDAVP-generated cAMP generation between kidneys of rats with lithium-induced NDI and control rats. In conclusion, the first proper cell model to study lithium-induced NDI was developed, and it was demonstrated that the lithium-induced downregulation of AQP2 and development of NDI occur independent of adenylyl cyclase activity in vitro and in vivo.

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“…For expression of G-AQP2-T125M, cells were transiently transfected with LipofectAmine according to the manufacturer's protocol (Invitrogen, Breda, The Netherlands). After growth to confluence, the cells were fixed and the AQP2 proteins were visualized by CLSM analysis as described (26).…”

Section: Mdck Cellsmentioning

confidence: 99%

Cell-Biologic and Functional Analyses of Five New Aquaporin-2 Missense Mutations that Cause Recessive Nephrogenic Diabetes Insipidus

Marr¹,

Bichet²,

Hoefs³

et al. 2002

Journal of the American Society of Nephrology

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110

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Abstract. Mutations in the Aquaporin-2 gene, which encodes a renal water channel, have been shown to cause autosomal nephrogenic diabetes insipidus (NDI), a disease in which the kidney is unable to concentrate urine in response to vasopressin. Most AQP2 missense mutants in recessive NDI are retained in the endoplasmic reticulum (ER), but AQP2-T125M and AQP2-G175R were reported to be nonfunctional channels unimpaired in their routing to the plasma membrane. In five families, seven novel AQP2 gene mutations were identified and their cell-biologic basis for causing recessive NDI was analyzed. The patients in four families were homozygous for mutations, encoding AQP2-L28P, AQP2-A47V, AQP2-V71M, or AQP2-P185A. Expression in oocytes revealed that all these mutants, and also AQP2-T125M and AQP2-G175R, conferred a reduced water permeability compared with wt-AQP2, which was due to ER retardation. The patient in the fifth family had a GϾA nucleotide substitution in the splice donor site of one allele that results in an out-of-frame protein.The other allele has a nucleotide deletion (c652delC) and a missense mutation (V194I). The routing and function of AQP2-V194I in oocytes was not different from wt-AQP2; it was therefore concluded that c652delC, which leads to an out-of-frame protein, is the NDI-causing mutation of the second allele. This study indicates that misfolding and ER retention is the main, and possibly only, cell-biologic basis for recessive NDI caused by missense AQP2 proteins. In addition, the reduced single channel water permeability of AQP2-A47V (40%) and AQP2-T125M (25%) might become of therapeutic value when chemical chaperones can be found that restore their routing to the plasma membrane.The aquaporin-2 (AQP2) water channel plays an important role in reabsorption of water in the kidney collecting duct and consequently in concentrating urine (1). Binding of arginine vasopressin (AVP) to its V2 receptor (AVPR2) at the basolateral side of principal cells of collecting ducts leads to an increase of intracellular cAMP levels, resulting in phosphorylation of AQP2 and possibly other proteins, by protein kinase A and subsequent redistribution of AQP2 from subapical storage vesicles to the apical plasma membrane. Driven by the interstitial hypertonicity, water reabsorption and urine concentration is thereby initiated. This process is reversed after dissociation of AVP from its receptor (2,3).Several mutations in the AVPR2 and AQP2 genes have been reported to cause congenital nephrogenic diabetes insipidus (NDI), a disease in which the kidney is unable to concentrate urine in response to AVP. Mutations in the AVPR2 gene result in NDI that is inherited as an X-linked recessive trait, whereas mutations in the AQP2 gene cause NDI that is inherited as either an autosomal recessive or a dominant trait (1,4 -6,7). Expression studies in oocytes showed that an AQP2 mutant in dominant NDI, AQP2-E258K, was a functional water channel but was retained in the region of the Golgi complex (7). In coexpression studies with wild-...

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Aquaporin-2: COOH terminus is necessary but not sufficient for routing to the apical membrane

Cited by 49 publications

References 45 publications

Quantitative phosphoproteomics of vasopressin-sensitive renal cells: Regulation of aquaporin-2 phosphorylation at two sites

Quantitative phosphoproteomics of vasopressin-sensitive renal cells: Regulation of aquaporin-2 phosphorylation at two sites

Development of Lithium-Induced Nephrogenic Diabetes Insipidus Is Dissociated from Adenylyl Cyclase Activity

Cell-Biologic and Functional Analyses of Five New Aquaporin-2 Missense Mutations that Cause Recessive Nephrogenic Diabetes Insipidus

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