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Chou CL, Limbutara K, Kao AR, Clark JZ, Nein EH, Raghuram V, Knepper MA. Collecting duct water permeability inhibition by EGF is associated with decreased cAMP, PKA activity, and AQP2 phosphorylation at Ser 269. Am J Physiol Renal Physiol 2024; 326:F545-F559. [PMID: 38205543 PMCID: PMC11208025 DOI: 10.1152/ajprenal.00197.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 01/03/2024] [Accepted: 01/03/2024] [Indexed: 01/12/2024] Open
Abstract
Prior studies showed that epidermal growth factor (EGF) inhibits vasopressin-stimulated osmotic water permeability in the renal collecting duct. Here, we investigated the underlying mechanism. Using isolated perfused rat inner medullary collecting ducts (IMCDs), we found that the addition of EGF to the peritubular bath significantly decreased 1-deamino-8-d-arginine vasopressin (dDAVP)-stimulated water permeability, confirming prior observations. The inhibitory effect of EGF on water permeability was associated with a reduction in intracellular cAMP levels and protein kinase A (PKA) activity. Using phospho-specific antibodies and immunoblotting in IMCD suspensions, we showed that EGF significantly reduces phosphorylation of AQP2 at Ser264 and Ser269. This effect was absent when 8-cpt-cAMP was used to induce AQP2 phosphorylation, suggesting that EGF's inhibitory effect was at a pre-cAMP step. Immunofluorescence labeling of microdissected IMCDs showed that EGF significantly reduced apical AQP2 abundance in the presence of dDAVP. To address what protein kinase might be responsible for Ser269 phosphorylation, we used Bayesian analysis to integrate multiple-omic datasets. Thirteen top-ranked protein kinases were subsequently tested by in vitro phosphorylation experiments for their ability to phosphorylate AQP2 peptides using a mass spectrometry readout. The results show that the PKA catalytic-α subunit increased phosphorylation at Ser256, Ser264, and Ser269. None of the other kinases tested phosphorylated Ser269. In addition, H-89 and PKI strongly inhibited dDAVP-stimulated AQP2 phosphorylation at Ser269. These results indicate that EGF decreases the water permeability of the IMCD by inhibiting cAMP production, thereby inhibiting PKA and decreasing AQP2 phosphorylation at Ser269, a site previously shown to regulate AQP2 endocytosis.NEW & NOTEWORTHY The authors used native rat collecting ducts to show that inhibition of vasopressin-stimulated water permeability by epidermal growth factor involves a reduction of aquaporin 2 phosphorylation at Ser269, a consequence of reduced cAMP production and PKA activity.
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Affiliation(s)
- Chung-Lin Chou
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Kavee Limbutara
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Anika R Kao
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Jevin Z Clark
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Ellen H Nein
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Viswanathan Raghuram
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Mark A Knepper
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States
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Cheung PW, Boukenna M, Babicz RSE, Mitra S, Kay A, Paunescu TC, Baylor N, Liu CCS, Nair AV, Bouley R, Brown D. Intracellular sites of AQP2 S256 phosphorylation identified using inhibitors of the AQP2 recycling itinerary. Am J Physiol Renal Physiol 2023; 324:F152-F167. [PMID: 36454701 PMCID: PMC9844975 DOI: 10.1152/ajprenal.00123.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 12/05/2022] Open
Abstract
Vasopressin (VP)-regulated aquaporin-2 (AQP2) trafficking between cytoplasmic vesicles and the plasma membrane of kidney principal cells is essential for water homeostasis. VP affects AQP2 phosphorylation at several serine residues in the COOH-terminus; among them, serine 256 (S256) appears to be a major regulator of AQP2 trafficking. Mutation of this serine to aspartic acid, which mimics phosphorylation, induces constitutive membrane expression of AQP2. However, the intracellular location(s) at which S256 phosphorylation occurs remains elusive. Here, we used strategies to block AQP2 trafficking at different cellular locations in LLC-PK1 cells and monitored VP-stimulated phosphorylation of S256 at these sites by immunofluorescence and Western blot analysis with phospho-specific antibodies. Using methyl-β-cyclodextrin, cold block or bafilomycin, and taxol, we blocked AQP2 at the plasma membrane, in the perinuclear trans-Golgi network, and in scattered cytoplasmic vesicles, respectively. Regardless of its cellular location, VP induced a significant increase in S256 phosphorylation, and this effect was not dependent on a functional microtubule cytoskeleton. To further investigate whether protein kinase A (PKA) was responsible for S256 phosphorylation in these cellular compartments, we created PKA-null cells and blocked AQP2 trafficking using the same procedures. We found that S256 phosphorylation was no longer increased compared with baseline, regardless of AQP2 localization. Taken together, our data indicate that AQP2 S256 phosphorylation can occur at the plasma membrane, in the trans-Golgi network, or in cytoplasmic vesicles and that this event is dependent on the expression of PKA in these cells.NEW & NOTEWORTHY Phosphorylation of aquaporin-2 by PKA at serine 256 (S256) occurs in various subcellular locations during its recycling itinerary, suggesting that the protein complex necessary for AQP2 S256 phosphorylation is present in these different recycling stations. Furthermore, we showed, using PKA-null cells, that PKA activity is required for vasopressin-induced AQP2 phosphorylation. Our data reveal a complex spatial pattern of intracellular AQP2 phosphorylation at S256, shedding new light on the role of phosphorylation in AQP2 membrane accumulation.
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Affiliation(s)
- Pui W Cheung
- Division of Nephrology, Program in Membrane Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Mey Boukenna
- Division of Nephrology, Program in Membrane Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Richard S E Babicz
- Division of Nephrology, Program in Membrane Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Shimontini Mitra
- Division of Nephrology, Program in Membrane Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Anna Kay
- Division of Nephrology, Program in Membrane Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Theodor C Paunescu
- Division of Nephrology, Program in Membrane Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Noah Baylor
- Division of Nephrology, Program in Membrane Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Chen-Chung Steven Liu
- Division of Nephrology, Program in Membrane Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Anil V Nair
- Division of Nephrology, Program in Membrane Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Richard Bouley
- Division of Nephrology, Program in Membrane Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Dennis Brown
- Division of Nephrology, Program in Membrane Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
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Park E, Yang CR, Raghuram V, Deshpande V, Datta A, Poll BG, Leo KT, Kikuchi H, Chen L, Chou CL, Knepper MA. Data resource: vasopressin-regulated protein phosphorylation sites in the collecting duct. Am J Physiol Renal Physiol 2023; 324:F43-F55. [PMID: 36264882 PMCID: PMC9762968 DOI: 10.1152/ajprenal.00229.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 10/04/2022] [Accepted: 10/17/2022] [Indexed: 02/04/2023] Open
Abstract
Vasopressin controls renal water excretion through actions to regulate aquaporin-2 (AQP2) trafficking, transcription, and degradation. These actions are in part dependent on vasopressin-induced phosphorylation changes in collecting duct cells. Although most efforts have focused on the phosphorylation of AQP2 itself, phosphoproteomic studies have identified many vasopressin-regulated phosphorylation sites in proteins other than AQP2. The goal of this bioinformatics-based review is to create a compendium of vasopressin-regulated phosphorylation sites with a focus on those that are seen in both native rat inner medullary collecting ducts and cultured collecting duct cells from the mouse (mpkCCD), arguing that these sites are the best candidates for roles in AQP2 regulation. This analysis identified 51 vasopressin-regulated phosphorylation sites in 45 proteins. We provide resource web pages at https://esbl.nhlbi.nih.gov/Databases/AVP-Phos/ and https://esbl.nhlbi.nih.gov/AVP-Network/, listing the phosphorylation sites and describing annotated functions of each of the vasopressin-targeted phosphoproteins. Among these sites are 23 consensus protein kinase A (PKA) sites that are increased in response to vasopressin, consistent with a central role for PKA in vasopressin signaling. The remaining sites are predicted to be phosphorylated by other kinases, most notably ERK1/2, which accounts for decreased phosphorylation at sites with a X-p(S/T)-P-X motif. Additional protein kinases that undergo vasopressin-induced changes in phosphorylation are Camkk2, Cdk18, Erbb3, Mink1, and Src, which also may be activated directly or indirectly by PKA. The regulated phosphoproteins are mapped to processes that hypothetically can account for vasopressin-mediated control of AQP2 trafficking, cytoskeletal alterations, and Aqp2 gene expression, providing grist for future studies.NEW & NOTEWORTHY Vasopressin regulates renal water excretion through control of the aquaporin-2 water channel in collecting duct cells. Studies of vasopressin-induced protein phosphorylation have focused mainly on the phosphorylation of aquaporin-2. This study describes 44 phosphoproteins other than aquaporin-2 that undergo vasopressin-mediated phosphorylation changes and summarizes potential physiological roles of each.
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Affiliation(s)
- Euijung Park
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Chin-Rang Yang
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Viswanathan Raghuram
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Venkatesh Deshpande
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Arnab Datta
- Laboratory of Translational Neuroscience, Division of Neuroscience, Yenepoya Research Center, Yenepoya (Deemed to be University), Mangalore, India
| | - Brian G Poll
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Kirby T Leo
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Hiroaki Kikuchi
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Lihe Chen
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Chung-Lin Chou
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Mark A Knepper
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
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Xiong M, Li C, Wang W, Yang B. Protein Structure and Modification of Aquaporins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1398:15-38. [PMID: 36717484 DOI: 10.1007/978-981-19-7415-1_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Aquaporins (AQPs) allow water molecules and other small, neutral solutes to quickly pass through membrane. The protein structures of AQPs solved by crystallographic methods or cryo-electron microscopy technology show that AQP monomer consists of six membrane-spanning alpha-helices that form the central water-transporting pore. AQP monomers assemble to form tetramers, forming the functional units in the membrane, to transport water or other small molecules. The biological functions of AQPs are regulated by posttranslational modifications, e.g., phosphorylation, ubiquitination, glycosylation, subcellular distribution, degradation and protein interactions. Modifications of AQP combined with structural properties contribute to a better functional mechanism of AQPs. Insight into the molecular mechanisms responsible for AQP modifications as well as gating and transport properties proved to be fundamental to the development of new therapeutic targets or reliable diagnostic and prognostic biomarkers.
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Affiliation(s)
- Mengyao Xiong
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Chunling Li
- Institute of Hypertension and Kidney Research, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Weidong Wang
- Institute of Hypertension and Kidney Research, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China.
| | - Baoxue Yang
- School of Basic Medical Sciences, Peking University, Beijing, China.
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Sun Z, Shao X, Wu H, Zhao Y, Cao Y, Li D, Sun Y, Wang Q. Loss of Pten in Renal Tubular Cells Leads to Water Retention by Upregulating AQP2. KIDNEY DISEASES (BASEL, SWITZERLAND) 2022; 9:58-71. [PMID: 36756085 PMCID: PMC9900467 DOI: 10.1159/000528010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Accepted: 10/26/2022] [Indexed: 12/02/2022]
Abstract
Introduction Phosphatase and tensin (PTEN) is a multifunctional gene associated with the normal development and physiological function of various tissues including the kidney. However, its role in renal tubular reabsorption function has not been well elucidated. Methods We generated a renal tubule-specific Pten knockout mouse model by crossing Ptenfl/fl mice with Ksp-Cre transgenic mice, evaluated the effect of Pten loss on renal tubular function, and investigated the underlying mechanisms. Results Pten loss resulted in abnormal renal structure and function and water retention in multiple organs. Our results also demonstrated that aquaporin-2 (AQP2), an important water channel protein, was upregulated and concentrated on the apical plasma membrane of collecting duct cells, which could be responsible for the impaired water balance in Pten loss mice. The regulation of Pten loss on AQP2 was mediated by protein kinase B (AKT) activation. Conclusions Our results reveal a connection between PTEN gene inactivation and water retention, suggesting the importance of PTEN in normal kidney development and function.
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Affiliation(s)
- Zhuo Sun
- Department of Pathology, Laboratory of Clinical and Experimental Pathology, Xuzhou Medical University, Xuzhou, China
| | - Xiaotong Shao
- Department of Pathology, Laboratory of Clinical and Experimental Pathology, Xuzhou Medical University, Xuzhou, China
| | - Haotian Wu
- Department of Pathology, Laboratory of Clinical and Experimental Pathology, Xuzhou Medical University, Xuzhou, China
| | - Yaxian Zhao
- Department of Pathology, Xuzhou Maternity and Child Health Care Hospital, Xuzhou, China
| | - Yidan Cao
- Department of Pathology, Wuxi No.2 People's Hospital, Wuxi, China
| | - Danhua Li
- Department of Pathology, Laboratory of Clinical and Experimental Pathology, Xuzhou Medical University, Xuzhou, China
| | - Ying Sun
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, China
| | - Qingling Wang
- Department of Pathology, Laboratory of Clinical and Experimental Pathology, Xuzhou Medical University, Xuzhou, China,*Qingling Wang,
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Bissonnette P, Lussier Y, Matar J, Leduc‐Nadeau A, Da Cal S, Arthus M, Unwin RJ, Steinke J, Rangaswamy D, Bichet DG. Further evidence for functional recovery of AQP2 mutations associated with nephrogenic diabetes insipidus. Physiol Rep 2021; 9:e14866. [PMID: 34120413 PMCID: PMC8198467 DOI: 10.14814/phy2.14866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 03/26/2021] [Accepted: 04/13/2021] [Indexed: 11/24/2022] Open
Abstract
Aquaporin-2 (AQP2) is a homotetrameric water channel responsible for the final water reuptake in the kidney. Disease-causing AQP2 mutations induce nephrogenic diabetes insipidus (NDI), a condition that challenges the bodily water balance by producing large urinary volumes. In this study, we characterize three new AQP2 mutations identified in our lab from NDI patients (A120D, A130V, T179N) along the previously reported A47V variant. Using Xenopus oocytes, we compared the key functional and biochemical features of these mutations against classical recessive (R187C) and dominant (R254Q) forms, and once again found clear functional recovery features (increased protein stability and function) for all mutations under study. This behaviour, attributed to heteromerization to wt-AQP2, challenge the classical model to NDI which often depicts recessive mutations as ill-structured proteins unable to oligomerize. Consequently, we propose a revised model to the cell pathophysiology of AQP2-related NDI which accounts for the functional recovery of recessive AQP2 mutations.
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Affiliation(s)
- Pierre Bissonnette
- Département de Pharmacologie et PhysiologieUniversité de MontréalMontréalQCCanada
| | - Yoann Lussier
- Département de Pharmacologie et PhysiologieUniversité de MontréalMontréalQCCanada
| | - Jessica Matar
- Département de Pharmacologie et PhysiologieUniversité de MontréalMontréalQCCanada
| | | | - Sandra Da Cal
- Département de Pharmacologie et PhysiologieUniversité de MontréalMontréalQCCanada
| | | | - Robert J. Unwin
- Department of Renal MedicineUniversity College LondonLondonUK
| | - Julia Steinke
- Division of Pediatric NephrologyHelen DeVos Children’s Hospital and ClinicsGrand RapidsMIUSA
| | - Dharshan Rangaswamy
- Department of NephrologyKasturba Medical CollegeKasturba HospitalManipal Academy of Higher EducationManipalKarnatakaIndia
| | - Daniel G. Bichet
- Département de Pharmacologie et PhysiologieUniversité de MontréalMontréalQCCanada
- Centre de RechercheHôpital du Sacré‐Cœur de MontréalMontréalQCCanada
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Fenton RA, Murali SK, Moeller HB. Advances in aquaporin-2 trafficking mechanisms and their implications for treatment of water balance disorders. Am J Physiol Cell Physiol 2020; 319:C1-C10. [PMID: 32432927 DOI: 10.1152/ajpcell.00150.2020] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In mammals, conservation of body water is critical for survival and is dependent on the kidneys' ability to minimize water loss in the urine during periods of water deprivation. The collecting duct water channel aquaporin-2 (AQP2) plays an essential role in this homeostatic response by facilitating water reabsorption along osmotic gradients. The ability to increase the levels of AQP2 in the apical plasma membrane following an increase in plasma osmolality is a rate-limiting step in water reabsorption, a process that is tightly regulated by the antidiuretic hormone arginine vasopressin (AVP). In this review, the focus is on the role of the carboxyl-terminus of AQP2 as a key regulatory point for AQP2 trafficking. We provide an overview of AQP2 structure, disease-causing mutations in the AQP2 carboxyl-terminus, the role of posttranslational modifications such as phosphorylation and ubiquitylation in the tail domain, and their implications for balanced trafficking of AQP2. Finally, we discuss how various modifications of the AQP2 tail facilitate selective protein-protein interactions that modulate the AQP2 trafficking mechanism.
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Affiliation(s)
- Robert A Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Hanne B Moeller
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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Chen Z, Zhuang J, Yang Q, Yang J, Wang D, Yu L, Chen M. Direct effect of protein kinase A on four putative phosphorylation sites of aquaporin 2 in vitro. Biochem Biophys Res Commun 2020; 525:505-511. [PMID: 32113684 DOI: 10.1016/j.bbrc.2020.02.049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 02/06/2020] [Accepted: 02/07/2020] [Indexed: 10/24/2022]
Abstract
The water channel aquaporin 2 (AQP2) has four phosphorylation sites at Ser256, Ser261, Ser264, and Ser269 in the C-terminus and these sites are important for AQP2 bioactivity. However, the exact role of each phosphorylation site still remains unclear. In this study, we generated unique AQP2 mutants in which we eliminated three phosphorylation sites but maintained only one site at the C-terminal end. The AQP2 phosphorylation of each single site by protein kinase A (PKA) was examined by in vitro translation and 32P incorporation. The ability of AQP2 trafficking to the cell membrane was evaluated by cell surface biotinylation. Among the four phosphorylation sites, AQP2 mutant with only S256 preserved the most ability of AQP2 to cell membrane expression. The AQP2 water permeability was measured in oocyte. Ser256 is the most important site for AQP2 function. Interestingly, Ser261 and Ser264 significantly inhibit AQP2 activity. Ser269 slightly but not statistically reduced AQP2 activity. Our data suggest that the four phosphorylation sites execute differential roles in concert in AQP2 functional regulation. AQP2 activity regulated by phosphorylation at Ser256 can be counterbalanced by phosphorylation at Ser261 and Ser264.
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Affiliation(s)
- Zhiyi Chen
- The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Jieqiu Zhuang
- Division of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Qing Yang
- Division of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Jianhuan Yang
- Division of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Dexuan Wang
- Division of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Linfang Yu
- Division of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Minguang Chen
- Division of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China.
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Chlorpromazine Induces Basolateral Aquaporin-2 Accumulation via F-Actin Depolymerization and Blockade of Endocytosis in Renal Epithelial Cells. Cells 2020; 9:cells9041057. [PMID: 32340337 PMCID: PMC7226349 DOI: 10.3390/cells9041057] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 04/13/2020] [Accepted: 04/19/2020] [Indexed: 12/11/2022] Open
Abstract
We previously showed that in polarized Madin-Darby canine kidney (MDCK) cells, aquaporin-2 (AQP2) is continuously targeted to the basolateral plasma membrane from which it is rapidly retrieved by clathrin-mediated endocytosis. It then undertakes microtubule-dependent transcytosis toward the apical plasma membrane. In this study, we found that treatment with chlorpromazine (CPZ, an inhibitor of clathrin-mediated endocytosis) results in AQP2 accumulation in the basolateral, but not the apical plasma membrane of epithelial cells. In MDCK cells, both AQP2 and clathrin were concentrated in the basolateral plasma membrane after CPZ treatment (100 µM for 15 min), and endocytosis was reduced. Then, using rhodamine phalloidin staining, we found that basolateral, but not apical, F-actin was selectively reduced by CPZ treatment. After incubation of rat kidney slices in situ with CPZ (200 µM for 15 min), basolateral AQP2 and clathrin were increased in principal cells, which simultaneously showed a significant decrease of basolateral compared to apical F-actin staining. These results indicate that clathrin-dependent transcytosis of AQP2 is an essential part of its trafficking pathway in renal epithelial cells and that this process can be inhibited by selectively depolymerizing the basolateral actin pool using CPZ.
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Cyclin-Dependent Kinase 18 Controls Trafficking of Aquaporin-2 and Its Abundance through Ubiquitin Ligase STUB1, Which Functions as an AKAP. Cells 2020; 9:cells9030673. [PMID: 32164329 PMCID: PMC7140648 DOI: 10.3390/cells9030673] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 02/27/2020] [Accepted: 03/09/2020] [Indexed: 12/24/2022] Open
Abstract
Arginine-vasopressin (AVP) facilitates water reabsorption in renal collecting duct principal cells through regulation of the water channel aquaporin-2 (AQP2). The hormone binds to vasopressin V2 receptors (V2R) on the surface of the cells and stimulates cAMP synthesis. The cAMP activates protein kinase A (PKA), which initiates signaling that causes an accumulation of AQP2 in the plasma membrane of the cells facilitating water reabsorption from primary urine and fine-tuning of body water homeostasis. AVP-mediated PKA activation also causes an increase in the AQP2 protein abundance through a mechanism that involves dephosphorylation of AQP2 at serine 261 and a decrease in its poly-ubiquitination. However, the signaling downstream of PKA that controls the localization and abundance of AQP2 is incompletely understood. We carried out an siRNA screen targeting 719 kinase-related genes, representing the majority of the kinases of the human genome and analyzed the effect of the knockdown on AQP2 by high-content imaging and biochemical approaches. The screening identified 13 hits whose knockdown inhibited the AQP2 accumulation in the plasma membrane. Amongst the candidates was the so far hardly characterized cyclin-dependent kinase 18 (CDK18). Our further analysis revealed a hitherto unrecognized signalosome comprising CDK18, an E3 ubiquitin ligase, STUB1 (CHIP), PKA and AQP2 that controls the localization and abundance of AQP2. CDK18 controls AQP2 through phosphorylation at serine 261 and STUB1-mediated ubiquitination. STUB1 functions as an A-kinase anchoring protein (AKAP) tethering PKA to the protein complex and bridging AQP2 and CDK18. The modulation of the protein complex may lead to novel concepts for the treatment of disorders which are caused or are associated with dysregulated AQP2 and for which a satisfactory treatment is not available, e.g., hyponatremia, liver cirrhosis, diabetes insipidus, ADPKD or heart failure.
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12
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Dorey ES, Walton SL, Kalisch‐Smith JI, Paravicini TM, Gardebjer EM, Weir KA, Singh RR, Bielefeldt‐Ohmann H, Anderson ST, Wlodek ME, Moritz KM. Periconceptional ethanol exposure induces a sex specific diuresis and increase in AQP2 and AVPR2 in the kidneys of aged rat offspring. Physiol Rep 2019; 7:e14273. [PMID: 31691500 PMCID: PMC6832009 DOI: 10.14814/phy2.14273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 10/04/2019] [Indexed: 12/11/2022] Open
Abstract
Maternal alcohol consumption can impair renal development and program kidney dysfunction in offspring. Given that most women who drink alcohol cease consumption upon pregnancy recognition, we aimed to investigate the effect of alcohol around the time of conception (PC:EtOH) on offspring renal development and function. Rats received a liquid diet ±12.5% v/v ethanol from 4 days before to 4 days after mating. At postnatal day 30, nephron number was assessed. Urine flow and electrolyte (Na, K, Cl) excretion was measured at 6 and 19 months and blood pressure at 12 months. At 19 months, kidneys were collected for gene and protein analysis and assessment of collecting duct length. At postnatal day 30, PC:EtOH offspring had fewer nephrons. At 6 months, PC:EtOH exposure did not alter urine flow nor affect blood pressure at 12 months. At 19 months, female but not male offspring exposed to PC:EtOH drank more water and had a higher urine flow despite no differences in plasma arginine vasopressin (AVP) concentrations. Aqp2 mRNA and Avpr2 mRNA and protein expression was increased in kidneys from female PC:EtOH offspring but collecting duct lengths were similar. Immunofluorescent staining revealed diffuse cytoplasmic distribution of AQP2 protein in kidneys from PC:EtOH females, compared with controls with apical AQP2 localization. PC:EtOH resulted in a low nephron endowment and in female offspring, associated with age-related diuresis. Changes in expression and cellular localization of AQP2 likely underpin this disturbance in water homeostasis and highlight the need for alcohol to be avoided in early pregnancy.
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Affiliation(s)
- Emily S. Dorey
- School of Biomedical SciencesThe University of QueenslandBrisbaneQueensland
| | - Sarah L. Walton
- School of Biomedical SciencesThe University of QueenslandBrisbaneQueensland
| | | | | | | | - Kristy A. Weir
- School of Biomedical SciencesThe University of QueenslandBrisbaneQueensland
| | - Reetu R. Singh
- School of Biomedical SciencesThe University of QueenslandBrisbaneQueensland
| | | | | | - Mary E. Wlodek
- The Department of PhysiologyThe University of MelbourneMelbourneVictoria
| | - Karen M. Moritz
- School of Biomedical SciencesThe University of QueenslandBrisbaneQueensland
- Child Health Research CentreThe University of QueenslandBrisbaneQueensland
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13
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Nooh MM, Kale A, Bahouth SW. Involvement of PDZ-SAP97 interactions in regulating AQP2 translocation in response to vasopressin in LLC-PK 1 cells. Am J Physiol Renal Physiol 2019; 317:F375-F387. [PMID: 31141395 PMCID: PMC6732448 DOI: 10.1152/ajprenal.00228.2018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 05/20/2019] [Accepted: 05/21/2019] [Indexed: 11/22/2022] Open
Abstract
Arginine-vasopressin (AVP)-mediated translocation of aquaporin-2 (AQP2) protein-forming water channels from storage vesicles to the membrane of renal collecting ducts is critical for the renal conservation of water. The type-1 PDZ-binding motif (PBM) in AQP2, "GTKA," is a critical barcode for its translocation, but its precise role and that of its interacting protein partners in this process remain obscure. We determined that synapse-associated protein-97 (SAP97), a membrane-associated guanylate kinase protein involved in establishing epithelial cell polarity, was an avid binding partner to the PBM of AQP2. The role of PBM and SAP97 on AQP2 redistribution in response to AVP was assessed in LLC-PK1 renal collecting cells by confocal microscopy and cell surface biotinylation techniques. These experiments indicated that distribution of AQP2 and SAP97 overlapped in the kidneys and LLC-PK1 cells and that knockdown of SAP97 inhibited the translocation of AQP2 in response to AVP. Binding between AQP2 and SAP97 was mediated by specific interactions between the second PDZ of SAP97 and PBM of AQP2. Mechanistically, inactivation of the PBM of AQP2, global delocalization of PKA, or knockdown of SAP97 inhibited AQP2 translocation as well as AVP- and forskolin-mediated phosphorylation of Ser256 in AQP2, which serves as the major translocation barcode of AQP2. These results suggest that the targeting of PKA to the microdomain of AQP2 via SAP97-AQP2 interactions in association with cross-talk between two barcodes in AQP2, namely, the PBM and phospho-Ser256, plays an important role in the translocation of AQP2 in the kidney.
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Affiliation(s)
- Mohammed M Nooh
- Department of Pharmacology, The University of Tennessee Health Sciences Center, Memphis, Tennessee
- Department of Biochemistry, Faculty of Pharmacy Cairo University, Cairo, Egypt
| | - Ajay Kale
- Department of Pharmacology, School of Pharmacy, University of Louisiana at Monroe, Monroe, Louisiana
| | - Suleiman W Bahouth
- Department of Pharmacology, The University of Tennessee Health Sciences Center, Memphis, Tennessee
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14
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Cheung PW, Terlouw A, Janssen SA, Brown D, Bouley R. Inhibition of non-receptor tyrosine kinase Src induces phosphoserine 256-independent aquaporin-2 membrane accumulation. J Physiol 2019; 597:1627-1642. [PMID: 30488437 PMCID: PMC6418769 DOI: 10.1113/jp277024] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 11/23/2018] [Indexed: 12/22/2022] Open
Abstract
KEY POINTS Aquaporin-2 (AQP2) is crucial for water homeostasis, and vasopressin (VP) induces AQP2 membrane trafficking by increasing intracellular cAMP, activating PKA and causing phosphorylation of AQP2 at serine 256, 264 and 269 residues and dephosphorylation of serine 261 residue on the AQP2 C-terminus. It is thought that serine 256 is the master regulator of AQP2 trafficking, and its phosphorylation has to precede the change of phosphorylation state of other serine residues. We found that Src inhibition causes serine 256-independent AQP2 membrane trafficking and induces phosphorylation of serine 269 independently of serine 256. This targeted phosphorylation of serine 269 is important for Src inhibition-induced AQP2 membrane accumulation; without serine 269, Src inhibition exerts no effect on AQP2 trafficking. This result helps us better understand the independent pathways that can target different AQP2 residues, and design new strategies to induce or sustain AQP2 membrane expression when VP signalling is defective. ABSTRACT Aquaporin-2 (AQP2) is essential for water homeostasis. Upon stimulation by vasopressin, AQP2 is phosphorylated at serine 256 (S256), S264 and S269, and dephosphorylated at S261. It is thought that S256 is the master regulator of AQP2 trafficking and membrane accumulation, and that its phosphorylation has to precede phosphorylation of other serine residues. In this study, we found that VP reduces Src kinase phosphorylation: by suppressing Src using the inhibitor dasatinib and siRNA, we could increase AQP2 membrane accumulation in cultured AQP2-expressing cells and in kidney collecting duct principal cells. Src inhibition increased exocytosis and inhibited clathrin-mediated endocytosis of AQP2, but exerted its effect in a cAMP, PKA and S256 phosphorylation (pS256)-independent manner. Despite the lack of S256 phosphorylation, dasatinib increased phosphorylation of S269, even in S256A mutant cells in which S256 phosphorylation cannot occur. To confirm the importance of pS269 in AQP2 re-distribution, we expressed an AQP2 S269A mutant in LLC-PK1 cells, and found that dasatinib no longer induced AQP2 membrane accumulation. In conclusion, Src inhibition causes phosphorylation of S269 independently of pS256, and induces AQP2 membrane accumulation by inhibiting clathrin-mediated endocytosis and increasing exocytosis. We conclude that S269 can be phosphorylated without pS256, and pS269 alone is important for AQP2 apical membrane accumulation under some conditions. These data increase our understanding of the independent pathways that can phosphorylate different residues in the AQP2 C-terminus, and suggest new strategies to target distinct AQP2 serine residues to induce membrane expression of this water channel when VP signalling is defective.
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Affiliation(s)
- Pui W. Cheung
- Center for Systems BiologyProgram in Membrane Biology and Division of NephrologyMassachusetts General Hospital and Harvard Medical SchoolBostonMAUSA
| | - Abby Terlouw
- Center for Systems BiologyProgram in Membrane Biology and Division of NephrologyMassachusetts General Hospital and Harvard Medical SchoolBostonMAUSA
| | - Sam Antoon Janssen
- Center for Systems BiologyProgram in Membrane Biology and Division of NephrologyMassachusetts General Hospital and Harvard Medical SchoolBostonMAUSA
| | - Dennis Brown
- Center for Systems BiologyProgram in Membrane Biology and Division of NephrologyMassachusetts General Hospital and Harvard Medical SchoolBostonMAUSA
| | - Richard Bouley
- Center for Systems BiologyProgram in Membrane Biology and Division of NephrologyMassachusetts General Hospital and Harvard Medical SchoolBostonMAUSA
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15
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Kim WY, Nam SA, Choi A, Kim YM, Park SH, Kim HL, Kim H, Han KH, Yang CW, Lee MS, Kim YK, Kim J. Atg7-dependent canonical autophagy regulates the degradation of aquaporin 2 in prolonged hypokalemia. Sci Rep 2019; 9:3021. [PMID: 30816234 PMCID: PMC6395725 DOI: 10.1038/s41598-019-39702-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 11/23/2018] [Indexed: 01/31/2023] Open
Abstract
Prolonged hypokalemia induces a decrease of urinary concentrating ability via down-regulation of aquaporin 2 (AQP2); however, the precise mechanisms remain unknown. To investigate the role of autophagy in the degradation of AQP2, we generated the principal cell-specific Atg7 deletion (Atg7Δpc) mice. In hypokalemic Atg7-floxed (Atg7f/f) mice, huge irregular shaped LC3-positive autophagic vacuoles accumulated mainly in inner medullary collecting duct (IMCD) cells. Total- and pS261-AQP2 were redistributed from apical and subapical domains into these vacuoles, which were not co-localized with RAB9. However, in the IMCD cells of hypokalemic Atg7Δpc mice, these canonical autophagic vacuoles were markedly reduced, whereas numerous small regular shaped LC3-negative/RAB9-positive non-canonical autophagic vacuoles were observed along with diffusely distributed total- and pS261-AQP2 in the cytoplasm. The immunoreactivity of pS256-AQP2 in the apical membrane of IMCD cells was markedly decreased, and no redistribution was observed in both hypokalemic Atg7f/f and Atg7Δpc mice. These findings suggest that AQP2 down regulation in hypokalemia was induced by reduced phosphorylation of AQP2, resulting in a reduction of apical plasma labeling of pS256-AQP2 and degradation of total- and pS261-AQP2 via an LC3/ATG7-dependent canonical autophagy pathway.
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Affiliation(s)
- Wan-Young Kim
- Department of Anatomy and Cell Death Disease Research Center, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Sun Ah Nam
- Department of Anatomy and Cell Death Disease Research Center, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Arum Choi
- Department of Anatomy and Cell Death Disease Research Center, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Yu-Mi Kim
- Department of Anatomy and Cell Death Disease Research Center, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Sang Hee Park
- Institute of Clinical Medicine Research of Bucheon St. Mary's Hospital, Bucheon, Korea
| | - Hong Lim Kim
- Integrative Research Support Center, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Hyang Kim
- Division of Nephrology, Kangbuk Samsung Hospital, Sungkyunkwan University, School of Medicine, Seoul, Korea
| | - Ki-Hwan Han
- Department of Anatomy, Ewha Womans University School of Medicine, Seoul, Korea
| | - Chul Woo Yang
- Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Myung-Shik Lee
- Severance Biomedical Science Institute, College of Medicine, Yonsei University, Seoul, Korea
| | - Yong Kyun Kim
- Department of Anatomy and Cell Death Disease Research Center, College of Medicine, The Catholic University of Korea, Seoul, Korea. .,Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
| | - Jin Kim
- Department of Anatomy and Cell Death Disease Research Center, College of Medicine, The Catholic University of Korea, Seoul, Korea.
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16
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Rinschen MM, Limbutara K, Knepper MA, Payne DM, Pisitkun T. From Molecules to Mechanisms: Functional Proteomics and Its Application to Renal Tubule Physiology. Physiol Rev 2019; 98:2571-2606. [PMID: 30182799 DOI: 10.1152/physrev.00057.2017] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Classical physiological studies using electrophysiological, biophysical, biochemical, and molecular techniques have created a detailed picture of molecular transport, bioenergetics, contractility and movement, and growth, as well as the regulation of these processes by external stimuli in cells and organisms. Newer systems biology approaches are beginning to provide deeper and broader understanding of these complex biological processes and their dynamic responses to a variety of environmental cues. In the past decade, advances in mass spectrometry-based proteomic technologies have provided invaluable tools to further elucidate these complex cellular processes, thereby confirming, complementing, and advancing common views of physiology. As one notable example, the application of proteomics to study the regulation of kidney function has yielded novel insights into the chemical and physical processes that tightly control body fluids, electrolytes, and metabolites to provide optimal microenvironments for various cellular and organ functions. Here, we systematically review, summarize, and discuss the most significant key findings from functional proteomic studies in renal epithelial physiology. We also identify further improvements in technological and bioinformatics methods that will be essential to advance precision medicine in nephrology.
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Affiliation(s)
- Markus M Rinschen
- Department II of Internal Medicine, University Hospital Cologne , Cologne , Germany ; Center for Molecular Medicine Cologne, University of Cologne , Cologne , Germany ; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne , Cologne , Germany ; Division of Nephrology, Faculty of Medicine, Chulalongkorn University , Bangkok , Thailand ; Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland ; and Center of Excellence in Systems Biology, Research Affairs, Faculty of Medicine, Chulalongkorn University , Bangkok , Thailand
| | - Kavee Limbutara
- Department II of Internal Medicine, University Hospital Cologne , Cologne , Germany ; Center for Molecular Medicine Cologne, University of Cologne , Cologne , Germany ; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne , Cologne , Germany ; Division of Nephrology, Faculty of Medicine, Chulalongkorn University , Bangkok , Thailand ; Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland ; and Center of Excellence in Systems Biology, Research Affairs, Faculty of Medicine, Chulalongkorn University , Bangkok , Thailand
| | - Mark A Knepper
- Department II of Internal Medicine, University Hospital Cologne , Cologne , Germany ; Center for Molecular Medicine Cologne, University of Cologne , Cologne , Germany ; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne , Cologne , Germany ; Division of Nephrology, Faculty of Medicine, Chulalongkorn University , Bangkok , Thailand ; Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland ; and Center of Excellence in Systems Biology, Research Affairs, Faculty of Medicine, Chulalongkorn University , Bangkok , Thailand
| | - D Michael Payne
- Department II of Internal Medicine, University Hospital Cologne , Cologne , Germany ; Center for Molecular Medicine Cologne, University of Cologne , Cologne , Germany ; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne , Cologne , Germany ; Division of Nephrology, Faculty of Medicine, Chulalongkorn University , Bangkok , Thailand ; Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland ; and Center of Excellence in Systems Biology, Research Affairs, Faculty of Medicine, Chulalongkorn University , Bangkok , Thailand
| | - Trairak Pisitkun
- Department II of Internal Medicine, University Hospital Cologne , Cologne , Germany ; Center for Molecular Medicine Cologne, University of Cologne , Cologne , Germany ; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne , Cologne , Germany ; Division of Nephrology, Faculty of Medicine, Chulalongkorn University , Bangkok , Thailand ; Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland ; and Center of Excellence in Systems Biology, Research Affairs, Faculty of Medicine, Chulalongkorn University , Bangkok , Thailand
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17
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Kuo KT, Yang CW, Yu MJ. Dexamethasone enhances vasopressin-induced aquaporin-2 gene expression in the mpkCCD cells. Am J Physiol Renal Physiol 2017; 314:F219-F229. [PMID: 29070569 DOI: 10.1152/ajprenal.00218.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The mouse cortical collecting duct cell (mpkCCD) has been an instrumental cell model for studying vasopressin-mediated aquaporin-2 regulation. This cell line was first developed by Vandewalle's group from a transgenic mouse carrying the transforming SV40 antigens driven by the pyruvate kinase promoter. To immortalize the cells, four hormone supplements (dexamethasone, epidermal growth factor, insulin, and triiodothyronine) were used to enhance SV40 antigen expression; however, these hormones appear to have various effects on aquaporin-2 gene expression in the cells. Here, we evaluated the effects of each hormone supplement and found that dexamethasone enhanced vasopressin-induced aquaporin-2 gene expression at both mRNA and protein levels in a dose- and time-dependent manner, without affecting mRNA or protein stability. The effects of dexamethasone were attributed largely to enhanced aquaporin-2 mRNA transcription in association with an enhanced aquaporin-2 promoter activity. Dexamethasone did not affect vasopressin-regulated aquaporin-2 phosphorylation and trafficking. In summary, we optimized the conditions to enhance vasopressin-induced endogenous aquaporin-2 gene expression in the mpkCCD cells. By increasing the amount of aquaporin-2 protein in the cells, our method will facilitate the study of aquaporin-2 cell physiology regulated by vasopressin.
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Affiliation(s)
- Kuang-Ting Kuo
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine , Taipei , Taiwan
| | - Chan-Wei Yang
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine , Taipei , Taiwan
| | - Ming-Jiun Yu
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine , Taipei , Taiwan
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18
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Lei L, Huang M, Su L, Xie D, Mamuya FA, Ham O, Tsuji K, Păunescu TG, Yang B, Lu HAJ. Manganese promotes intracellular accumulation of AQP2 via modulating F-actin polymerization and reduces urinary concentration in mice. Am J Physiol Renal Physiol 2017; 314:F306-F316. [PMID: 29046300 DOI: 10.1152/ajprenal.00391.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Aquaporin-2 (AQP2) is a water channel protein expressed in principal cells (PCs) of the kidney collecting ducts (CDs) and plays a critical role in mediating water reabsorption and urine concentration. AQP2 undergoes both regulated trafficking mediated by vasopressin (VP) and constitutive recycling, which is independent of VP. For both pathways, actin cytoskeletal dynamics is a key determinant of AQP2 trafficking. We report here that manganese chloride (MnCl2) is a novel and potent regulator of AQP2 trafficking in cultured cells and in the kidney. MnCl2 treatment promoted internalization and intracellular accumulation of AQP2. The effect of MnCl2 on the intracellular accumulation of AQP2 was associated with activation of RhoA and actin polymerization without modification of AQP2 phosphorylation. Although the level of total and phosphorylated AQP2 did not change, MnCl2 treatment impeded VP-induced phosphorylation of AQP2 at its serine-256, -264, and -269 residues and dephosphorylation at serine 261. In addition, MnCl2 significantly promoted F-actin polymerization along with downregulation of RhoA activity and prevented VP-induced membrane accumulation of AQP2. Finally, MnCl2 treatment in mice resulted in significant polyuria and reduced urinary concentration, likely due to intracellular relocation of AQP2 in the PCs of kidney CDs. More importantly, the reduced urinary concentration caused by MnCl2 treatment in animals was not corrected by VP. In summary, our study identified a novel effect of MnCl2 on AQP2 trafficking through modifying RhoA activity and actin polymerization and uncovered its potent impact on water diuresis in vivo.
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Affiliation(s)
- Lei Lei
- Department of Pharmacology, School of Basic Medical Sciences, Peking University , Beijing , People's Republic of China.,Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts
| | - Ming Huang
- Department of Pharmacology, School of Basic Medical Sciences, Peking University , Beijing , People's Republic of China.,Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts
| | - Limin Su
- Department of Pharmacology, School of Basic Medical Sciences, Peking University , Beijing , People's Republic of China.,Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts
| | - Dongping Xie
- Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts
| | - Fahmy A Mamuya
- Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
| | - Onju Ham
- Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
| | - Kenji Tsuji
- Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
| | - Teodor G Păunescu
- Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
| | - Baoxue Yang
- Department of Pharmacology, School of Basic Medical Sciences, Peking University , Beijing , People's Republic of China
| | - Hua A Jenny Lu
- Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
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19
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Lin Y, Zhang T, Feng P, Qiu M, Liu Q, Li S, Zheng P, Kong Y, Levi M, Li C, Wang W. Aliskiren increases aquaporin-2 expression and attenuates lithium-induced nephrogenic diabetes insipidus. Am J Physiol Renal Physiol 2017; 313:F914-F925. [PMID: 28228402 PMCID: PMC6148297 DOI: 10.1152/ajprenal.00553.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 02/08/2017] [Accepted: 02/08/2017] [Indexed: 11/22/2022] Open
Abstract
The direct renin inhibitor aliskiren has been shown to be retained and persist in medullary collecting ducts even after treatment is discontinued, suggesting a new mechanism of action for this drug. The purpose of the present study was to investigate whether aliskiren regulates renal aquaporin expression in the collecting ducts and improves urinary concentrating defect induced by lithium in mice. The mice were fed with either normal chow or LiCl diet (40 mmol·kg dry food-1·day-1 for 4 days and 20 mmol·kg dry food-1·day-1 for the last 3 days) for 7 days. Some mice were intraperitoneally injected with aliskiren (50 mg·kg body wt-1·day-1 in saline). Aliskiren significantly increased protein abundance of aquaporin-2 (AQP2) in the kidney inner medulla in mice. In inner medulla collecting duct cell suspension, aliskiren markedly increased AQP2 and phosphorylated AQP2 at serine 256 (pS256-AQP2) protein abundance, which was significantly inhibited both by adenylyl cyclase inhibitor MDL-12330A and by PKA inhibitor H89, indicating an involvement of the cAMP-PKA signaling pathway in aliskiren-induced increased AQP2 expression. Aliskiren treatment improved urinary concentrating defect in lithium-treated mice and partially prevented the decrease of AQP2 and pS256-AQP2 protein abundance in the inner medulla of the kidney. In conclusion, the direct renin inhibitor aliskiren upregulates AQP2 protein expression in inner medullary collecting duct principal cells and prevents lithium-induced nephrogenic diabetes insipidus likely via cAMP-PKA pathways.
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Affiliation(s)
- Yu Lin
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Tiezheng Zhang
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Pinning Feng
- Department of Clinical Laboratory, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China; and
| | - Miaojuan Qiu
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Qiaojuan Liu
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Suchun Li
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Peili Zheng
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Yonglun Kong
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Moshe Levi
- Department of Medicine, Division of Hypertension and Renal Diseases, University of Colorado Denver, Aurora, Colorado
| | - Chunling Li
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Weidong Wang
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China;
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20
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Li W, Jin WW, Tsuji K, Chen Y, Nomura N, Su L, Yui N, Arthur J, Cotecchia S, Paunescu TG, Brown D, Lu HAJ. Ezrin directly interacts with AQP2 and promotes its endocytosis. J Cell Sci 2017; 130:2914-2925. [PMID: 28754689 DOI: 10.1242/jcs.204842] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 07/21/2017] [Indexed: 11/20/2022] Open
Abstract
The water channel aquaporin-2 (AQP2) is a major regulator of water homeostasis in response to vasopressin (VP). Dynamic trafficking of AQP2 relies on its close interaction with trafficking machinery proteins and the actin cytoskeleton. Here, we report the identification of ezrin, an actin-binding protein from the ezrin/radixin/moesin (ERM) family as an AQP2-interacting protein. Ezrin was first detected in a co-immunoprecipitation (co-IP) complex using an anti-AQP2 antibody in a proteomic analysis. Immunofluorescence staining revealed the co-expression of ezrin and AQP2 in collecting duct principal cells, and VP treatment caused redistribution of both proteins to the apical membrane. The ezrin-AQP2 interaction was confirmed by co-IP experiments with an anti-ezrin antibody, and by pulldown assays using purified full-length and FERM domain-containing recombinant ezrin. By using purified recombinant proteins, we showed that ezrin directly interacts with AQP2 C-terminus through its N-terminal FERM domain. Knocking down ezrin expression with shRNA resulted in increased membrane accumulation of AQP2 and reduced AQP2 endocytosis. Therefore, through direct interaction with AQP2, ezrin facilitates AQP2 endocytosis, thus linking the dynamic actin cytoskeleton network with AQP2 trafficking.
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Affiliation(s)
- Wei Li
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - William W Jin
- Washington University in St. Louis, College of Arts and Sciences, St Louis, MO 63130, USA
| | - Kenji Tsuji
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - Ying Chen
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - Naohiro Nomura
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - Limin Su
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA.,Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing 100191, China
| | - Naofumi Yui
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - Julian Arthur
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - Susanna Cotecchia
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne 1005, Switzerland
| | - Teodor G Paunescu
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - Dennis Brown
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
| | - Hua A J Lu
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA
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21
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Roche JV, Survery S, Kreida S, Nesverova V, Ampah-Korsah H, Gourdon M, Deen PMT, Törnroth-Horsefield S. Phosphorylation of human aquaporin 2 (AQP2) allosterically controls its interaction with the lysosomal trafficking protein LIP5. J Biol Chem 2017; 292:14636-14648. [PMID: 28710278 DOI: 10.1074/jbc.m117.788364] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Revised: 07/07/2017] [Indexed: 12/21/2022] Open
Abstract
The interaction between the renal water channel aquaporin-2 (AQP2) and the lysosomal trafficking regulator-interacting protein LIP5 targets AQP2 to multivesicular bodies and facilitates lysosomal degradation. This interaction is part of a process that controls AQP2 apical membrane abundance in a vasopressin-dependent manner, allowing for urine volume adjustment. Vasopressin regulates phosphorylation at four sites within the AQP2 C terminus (Ser256, Ser261, Ser264, and Thr269), of which Ser256 is crucial and sufficient for AQP2 translocation from storage vesicles to the apical membrane. However, whether AQP2 phosphorylation modulates AQP2-LIP5 complex affinity is unknown. Here we used far-Western blot analysis and microscale thermophoresis to show that the AQP2 binds LIP5 in a phosphorylation-dependent manner. We constructed five phospho-mimicking mutants (S256E, S261E, S264E, T269E, and S256E/T269E) and a C-terminal truncation mutant (ΔP242) that lacked all phosphorylation sites but retained a previously suggested LIP5-binding site. CD spectroscopy indicated that wild-type AQP2 and the phospho-mimicking mutants had similar overall structure but displayed differences in melting temperatures possibly arising from C-terminal conformational changes. Non-phosphorylated AQP2 bound LIP5 with the highest affinity, whereas AQP2-ΔP242 had 20-fold lower affinity as determined by microscale thermophoresis. AQP2-S256E, S261E, T269E, and S256E/T269E all had reduced affinity. This effect was most prominent for AQP2-S256E, which fits well with its role in apical membrane targeting. AQP2-S264E had affinity similar to non-phosphorylated AQP2, possibly indicating a role in exosome excretion. Our data suggest that AQP2 phosphorylation allosterically controls its interaction with LIP5, illustrating how altered affinities to interacting proteins form the basis for regulation of AQP2 trafficking by post-translational modifications.
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Affiliation(s)
- Jennifer Virginia Roche
- From the Department of Biochemistry and Structural Biology, Lund University, 221 00 Lund, Sweden and
| | - Sabeen Survery
- From the Department of Biochemistry and Structural Biology, Lund University, 221 00 Lund, Sweden and
| | - Stefan Kreida
- From the Department of Biochemistry and Structural Biology, Lund University, 221 00 Lund, Sweden and
| | - Veronika Nesverova
- From the Department of Biochemistry and Structural Biology, Lund University, 221 00 Lund, Sweden and
| | - Henry Ampah-Korsah
- From the Department of Biochemistry and Structural Biology, Lund University, 221 00 Lund, Sweden and
| | - Maria Gourdon
- From the Department of Biochemistry and Structural Biology, Lund University, 221 00 Lund, Sweden and
| | - Peter M T Deen
- the Department of Physiology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
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22
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Abstract
Aquaporins (AQPs ) are a family of membrane water channels that basically function as regulators of intracellular and intercellular water flow. To date, thirteen AQPs , which are distributed widely in specific cell types in various organs and tissues, have been characterized in humans. Four AQP monomers, each of which consists of six membrane-spanning alpha-helices that have a central water-transporting pore, assemble to form tetramers, forming the functional units in the membrane. AQP facilitates osmotic water transport across plasma membranes and thus transcellular fluid movement. The cellular functions of aquaporins are regulated by posttranslational modifications , e.g. phosphorylation, ubiquitination, glycosylation, subcellular distribution, degradation, and protein interactions. Insight into the molecular mechanisms responsible for regulated aquaporin trafficking and synthesis is proving to be fundamental for development of novel therapeutic targets or reliable diagnostic and prognostic biomarkers.
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Affiliation(s)
- Chunling Li
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, 74# Zhongshan Er Road, Guangzhou, 510080, China
| | - Weidong Wang
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, 74# Zhongshan Er Road, Guangzhou, 510080, China.
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23
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Mamuya FA, Cano-Peñalver JL, Li W, Rodriguez Puyol D, Rodriguez Puyol M, Brown D, de Frutos S, Lu HAJ. ILK and cytoskeletal architecture: an important determinant of AQP2 recycling and subsequent entry into the exocytotic pathway. Am J Physiol Renal Physiol 2016; 311:F1346-F1357. [PMID: 27760768 DOI: 10.1152/ajprenal.00336.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 09/29/2016] [Accepted: 10/11/2016] [Indexed: 12/20/2022] Open
Abstract
Within the past decade tremendous efforts have been made to understand the mechanism behind aquaporin-2 (AQP2) water channel trafficking and recycling, to open a path toward effective diabetes insipidus therapeutics. A recent study has shown that integrin-linked kinase (ILK) conditional-knockdown mice developed polyuria along with decreased AQP2 expression. To understand whether ILK also regulates AQP2 trafficking in kidney tubular cells, we performed in vitro analysis using LLCPK1 cells stably expressing rat AQP2 (LLC-AQP2 cells). Upon treatment of LLC-AQP2 cells with ILK inhibitor cpd22 and ILK-siRNA, we observed increased accumulation of AQP2 in the perinuclear region, without any significant increase in the rate of endocytosis. This perinuclear accumulation did not occur in cells expressing a serine-256-aspartic acid mutation that retains AQP2 in the plasma membrane. We then examined clathrin-mediated endocytosis after ILK inhibition using rhodamine-conjugated transferrin. Despite no differences in overall transferrin endocytosis, the endocytosed transferrin also accumulated in the perinuclear region where it colocalized with AQP2. These accumulated vesicles also contained the recycling endosome marker Rab11. In parallel, the usual vasopressin-induced AQP2 membrane accumulation was prevented after ILK inhibition; however, ILK inhibition did not measurably affect AQP2 phosphorylation at serine-256 or its dephosphorylation at serine-261. Instead, we found that inhibition of ILK increased F-actin polymerization. When F-actin was depolymerized with latrunculin, the perinuclear located AQP2 dispersed. We conclude that ILK is important in orchestrating dynamic cytoskeletal architecture during recycling of AQP2, which is necessary for its subsequent entry into the exocytotic pathway.
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Affiliation(s)
- Fahmy A Mamuya
- Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Jose Luis Cano-Peñalver
- Department of Systems Biology, Physiology Unit, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain; Instituto Reina Sofia de Investigación Renal and Red de Investigación Renal (REDinREN), Instituto de Salud Carlos III, Madrid, Spain; and
| | - Wei Li
- Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Diego Rodriguez Puyol
- Biomedical Research Foundation and Nephrology Department, Hospital Príncipe de Asturias, Alcalá de Henares, and Instituto Reina Sofia de Investigación Renal and REDinREN from Instituto de Salud Carlos III, Madrid, Spain
| | - Manuel Rodriguez Puyol
- Department of Systems Biology, Physiology Unit, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain; Instituto Reina Sofia de Investigación Renal and Red de Investigación Renal (REDinREN), Instituto de Salud Carlos III, Madrid, Spain; and
| | - Dennis Brown
- Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Sergio de Frutos
- Department of Systems Biology, Physiology Unit, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain; Instituto Reina Sofia de Investigación Renal and Red de Investigación Renal (REDinREN), Instituto de Salud Carlos III, Madrid, Spain; and
| | - Hua Ann Jenny Lu
- Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts;
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24
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Lee MS, Choi HJ, Park EJ, Park HJ, Kwon TH. Depletion of vacuolar protein sorting-associated protein 35 is associated with increased lysosomal degradation of aquaporin-2. Am J Physiol Renal Physiol 2016; 311:F1294-F1307. [PMID: 27733367 DOI: 10.1152/ajprenal.00307.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 09/22/2016] [Accepted: 10/07/2016] [Indexed: 11/22/2022] Open
Abstract
The carboxyl terminus of aquaporin-2 (AQP2c) undergoes posttranslational modifications, including phosphorylation and ubiquitination, in the process of regulating aquaporin-2 (AQP2) translocation and protein abundance. We aimed to identify novel proteins interacting with AQP2c. Recombinant AQP2c protein was made in Escherichia coli BL21 (DE3) cells by exploiting the pET32 TrxA fusion system. Lysates of rat kidney inner medullary collecting duct (IMCD) tubule suspensions interacted with rat AQP2c bound to Ni2+-resin were subjected to LC-MS/MS proteomic analysis. Potential interacting proteins were identified, including vacuolar protein sorting-associated protein 35 (Vps35). Coimmunoprecipitation assay demonstrated that Vps35 interacted with AQP2c. Immunohistochemistry of rat kidney revealed that AQP2 and Vps35 were partly colocalized at the intracellular vesicles in collecting duct cells. The role of Vps35 in AQP2 regulation induced by 1-deamino-8D-arginine vasopressin (dDAVP) was examined in mpkCCDc14 cells. Cell surface biotinylation assay demonstrated that dDAVP-induced apical translocation of AQP2 was significantly decreased under siRNA-mediated Vps35 knockdown. dDAVP-induced AQP2 upregulation was less prominent in the cells with Vps35 knockdown. Moreover, AQP2 protein abundance was decreased to a greater extent during the withdrawal period after dDAVP stimulation under Vps35 knockdown, which was significantly inhibited by chloroquine (a blocker of the lysosomal pathway) but not by MG132 (a proteasome inhibitor). Immunocytochemistry demonstrated that internalized AQP2 was more associated with lysosomal-associated membrane protein 1 (LAMP-1) in primary cultured IMCD cells under a Vps35 knockdown situation. Taken together, our results show that Vps35 interacts with AQP2c, and depletion of Vps35 is likely to be associated with decreased AQP2 trafficking and increased lysosomal degradation of AQP2 protein.
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Affiliation(s)
- Mi Suk Lee
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Taegu, Korea; and.,BK21 Plus KNU Biomedical Convergence Program, Department of Biomedical Science, Kyungpook National University, Taegu, Korea
| | - Hyo-Jung Choi
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Taegu, Korea; and
| | - Eui-Jung Park
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Taegu, Korea; and.,BK21 Plus KNU Biomedical Convergence Program, Department of Biomedical Science, Kyungpook National University, Taegu, Korea
| | - Hye-Jeong Park
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Taegu, Korea; and.,BK21 Plus KNU Biomedical Convergence Program, Department of Biomedical Science, Kyungpook National University, Taegu, Korea
| | - Tae-Hwan Kwon
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Taegu, Korea; and .,BK21 Plus KNU Biomedical Convergence Program, Department of Biomedical Science, Kyungpook National University, Taegu, Korea
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