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Calcium-Sensing Receptor and Regulation of WNK Kinases in the Kidney. Cells 2020; 9:cells9071644. [PMID: 32659887 PMCID: PMC7407487 DOI: 10.3390/cells9071644] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 07/01/2020] [Accepted: 07/06/2020] [Indexed: 12/27/2022] Open
Abstract
The kidney is essential for systemic calcium homeostasis. Urinary calcium excretion can be viewed as an integrative renal response to endocrine and local stimuli. The extracellular calcium-sensing receptor (CaSR) elicits a number of adaptive reactions to increased plasma Ca2+ levels including the control of parathyroid hormone release and regulation of the renal calcium handling. Calcium reabsorption in the distal nephron of the kidney is functionally coupled to sodium transport. Apart from Ca2+ transport systems, CaSR signaling affects relevant distal Na+-(K+)-2Cl- cotransporters, NKCC2 and NCC. NKCC2 and NCC are activated by a kinase cascade comprising with-no-lysine [K] kinases (WNKs) and two homologous Ste20-related kinases, SPAK and OSR1. Gain-of-function mutations within the WNK-SPAK/OSR1-NKCC2/NCC pathway lead to renal salt retention and hypertension, whereas loss-of-function mutations have been associated with salt-losing tubulopathies such as Bartter or Gitelman syndromes. A Bartter-like syndrome has been also described in patients carrying gain-of-function mutations in the CaSR gene. Recent work suggested that CaSR signals via the WNK-SPAK/OSR1 cascade to modulate salt reabsorption along the distal nephron. The review presented here summarizes the latest progress in understanding of functional interactions between CaSR and WNKs and their potential impact on the renal salt handling and blood pressure.
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2
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Bulacio RP, Torres AM. Caveolin-2 in urine as a novel biomarker of renal recovery after cisplatin induced nephrotoxicity in rats. Toxicol Lett 2019; 313:169-177. [DOI: 10.1016/j.toxlet.2019.07.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 07/01/2019] [Accepted: 07/04/2019] [Indexed: 02/05/2023]
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Saxena V, Fitch J, Ketz J, White P, Wetzel A, Chanley MA, Spencer JD, Becknell B, Pierce KR, Arregui SW, Nelson RD, Schwartz GJ, Velazquez V, Walker LA, Chen X, Yan P, Hains DS, Schwaderer AL. Whole Transcriptome Analysis of Renal Intercalated Cells Predicts Lipopolysaccharide Mediated Inhibition of Retinoid X Receptor alpha Function. Sci Rep 2019; 9:545. [PMID: 30679625 PMCID: PMC6345901 DOI: 10.1038/s41598-018-36921-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 11/23/2018] [Indexed: 01/14/2023] Open
Abstract
The renal collecting duct consists of intercalated cells (ICs) and principal cells (PCs). We have previously demonstrated that collecting ducts have a role in the innate immune defense of the kidney. Transcriptomics is an important tool used to enhance systems-level understanding of cell biology. However, transcriptomics performed on whole kidneys provides limited insight of collecting duct cell gene expression, because these cells comprise a small fraction of total kidney cells. Recently we generated reporter mouse models to enrich collecting duct specific PC and ICs and reported targeted gene expression of anti-microbial peptide genes. Here we report transcriptomics on enriched ICs and PCs and performed a pilot study sequencing four single ICs. We identified 3,645 genes with increased relative expression in ICs compared to non-ICs. In comparison to non-PCs, 2,088 genes had higher relative expression in PCs. IC associated genes included the innate interleukin 1 receptor, type 1 and the antimicrobial peptide(AMP) adrenomedullin. The top predicted canonical pathway for enriched ICs was lipopolysaccharide/Interleukin 1 mediated inhibition of Retinoid X Receptor alpha function and decreased Retinoid X Receptor expression was confirmed to occur 1-hour post experimental murine UTI in ICs but not in non-ICs.
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Affiliation(s)
- Vijay Saxena
- Indiana University School of Medicine, Riley Children's Hospital, Indianapolis, Indiana, United States.
| | - James Fitch
- The Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, United States
| | - John Ketz
- The Research Institute at Nationwide Children's, Center for Clinical and Translational Research, Columbus, Ohio, and College of Medicine, Ohio State University, Columbus, Ohio, United States
| | - Peter White
- The Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, United States
- Department of Pediatrics, College of Medicine, The Ohio State University, Columbus, Ohio, United States
| | - Amy Wetzel
- The Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, United States
| | - Melinda A Chanley
- The Research Institute at Nationwide Children's, Center for Clinical and Translational Research, Columbus, Ohio, and College of Medicine, Ohio State University, Columbus, Ohio, United States
| | - John D Spencer
- The Research Institute at Nationwide Children's, Center for Clinical and Translational Research, Columbus, Ohio, and College of Medicine, Ohio State University, Columbus, Ohio, United States
- Department of Pediatrics, College of Medicine, The Ohio State University, Columbus, Ohio, United States
| | - Brian Becknell
- The Research Institute at Nationwide Children's, Center for Clinical and Translational Research, Columbus, Ohio, and College of Medicine, Ohio State University, Columbus, Ohio, United States
- Department of Pediatrics, College of Medicine, The Ohio State University, Columbus, Ohio, United States
| | - Keith R Pierce
- Innate Immunity Translational Research Center, Children's Foundation Research Institute at Le Bonheur Children's Hospital, Memphis, Tennessee, United States
| | - Sam W Arregui
- Indiana University School of Medicine, Riley Children's Hospital, Indianapolis, Indiana, United States
| | - Raoul D Nelson
- Division of Nephrology, Department of Pediatrics, University of Utah, Salt Lake City, Utah, United States
| | - George J Schwartz
- University of Rochester Medical Center, School of Medicine and Dentistry, Rochester, New York, United States
| | - Victoria Velazquez
- Research Institute at Nationwide Children's Hospital Flow Cytometry Core Laboratory, Columbus, Ohio, United States
| | - Logan A Walker
- Department of Physics, College of Arts and Sciences, The Ohio State University, Columbus, Ohio, United States
| | - Xi Chen
- Genomics Shared Resource, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States
| | - Pearlly Yan
- Genomics Shared Resource, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States
- Division of Hematology, Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
| | - David S Hains
- Indiana University School of Medicine, Riley Children's Hospital, Indianapolis, Indiana, United States.
| | - Andrew L Schwaderer
- Indiana University School of Medicine, Riley Children's Hospital, Indianapolis, Indiana, United States.
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Bulacio RP, Nosetto EC, Brandoni A, Torres AM. Novel finding of caveolin-2 in apical membranes of proximal tubule and first detection of caveolin-2 in urine: A promising biomarker of renal disease. J Cell Biochem 2018; 120:4966-4974. [PMID: 30269377 DOI: 10.1002/jcb.27772] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 09/06/2018] [Indexed: 12/14/2022]
Abstract
Caveolin-2 (Cav-2) is expressed in a variety of cell tissue, and it has also been found in renal tissue. The expression of Cav-2 in proximal tubules is still unclear. The aim of this study was to carry out a complete evaluation of the expression pattern of Cav-2 in rat renal cortex to clarify and deepen the knowledge about the localization of Cav-2 in the proximal tubules and also to evaluate its presence in urine. Male Wistar rats were used to assess Cav-2 expression by Western blot analysis in homogenates, apical, and basolateral membranes from kidney cortex, in lysates and total plasma membranes from renal cortical cell suspensions, in urine, and in urinary exosomes. Cav-2 was clearly expressed in renal cortex homogenates and in both apical and basolateral membranes isolated from kidney cortex, with a greater expression on the former membranes. It was also observed in lysates and in plasma membranes from cortical cell suspensions. Moreover, Cav-2 was found in urine and in its exosomal fraction. These results confirmed the presence of Cav-2 in proximal tubule cells in the kidney of healthy rats, and showed for the first time its expression at the apical membrane of these cells and in urine. Besides, urinary exosomal pathway could be involved in Cav-2 urinary excretion under normal conditions. We observed an increase in the urinary abundance of Cav-2 in two models of acute kidney injury, and thus we proposed the urinary excretion of Cav-2 as a potential biomarker of kidney injury.
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Affiliation(s)
- Romina Paula Bulacio
- Área Farmacología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Evangelina Cecilia Nosetto
- Área Farmacología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Anabel Brandoni
- Área Farmacología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Adriana Mónica Torres
- Área Farmacología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
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Li Y, Hu H, O'Neil RG. Caveolae facilitate TRPV4-mediated Ca 2+ signaling and the hierarchical activation of Ca 2+-activated K + channels in K +-secreting renal collecting duct cells. Am J Physiol Renal Physiol 2018; 315:F1626-F1636. [PMID: 30207167 DOI: 10.1152/ajprenal.00076.2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Transient receptor potential cation channel subfamily V member 4 (TRPV4)-mediated Ca2+ signaling induces early activation of small/intermediate Ca2+-activated K+ channels, SK3 (KCNN3) and IK1 (KCNN4), which leads to membrane hyperpolarization and enhanced Ca2+ influx, which is critical for subsequent activation of the large conductance Ca2+-activated K+ channel BK (KCNMA1) and K+ secretion in kidney cortical collecting duct (CCD) cells. The focus of the present study was to determine if such coordinated hierarchical/sequential activation of these channels in CCD was orchestrated within caveolae, a known microcompartment underlying selective Ca2+-signaling events in other cells. In K+-secreting mouse principal cell (PC) line, mCCDcl1 cells, knockdown of caveolae caveolin-1 (CAV-1) depressed TRPV4-mediated Ca2+ signaling and activation of SK3, intermediate conductance channel (IK1), and BK. Immunofluorescence colocalization analysis and coimmunoprecipitation assays demonstrated direct coupling of TRPV4 with each of the KCa channels in both mCCDcl1 and whole mouse kidney homogenates. Likewise, extending this analysis to CAV-1 demonstrates colocalization and direct coupling of CAV-1 with TRPV4, SK3, IK1, and BK, providing strong support for coupling of the channels in caveolae microdomains. Furthermore, differential expression of CAV-1 along the CCD was apparent where CAV-1 was strongly expressed within and along the cell borders of kidney PCs and intercalated cells (ICs), although significantly less in ICs. It is concluded that caveolae provide a key microdomain in PCs and ICs for coupling of TRPV4 with SK3, IK1, and BK that directly contributes to TRPV4-mediated Ca2+ signaling in these domains leading to rapid and sequential coupling of TRPV4-SK3/IK1-BK that may play a central role in mediating Ca2+-dependent regulation of BK and K+ secretion.
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Affiliation(s)
- Yue Li
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston , Houston, Texas
| | - Hongxiang Hu
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston , Houston, Texas
| | - Roger G O'Neil
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston , Houston, Texas
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6
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Abstract
Caveolin-1 (Cav1) is essential for the formation of caveolae. Little is known about their functional role in the kidney. We tested the hypothesis that caveolae modulate renal salt and water reabsorption. Wild-type (WT) and Cav1-deficient (Cav1−/−) mice were studied. Cav1 expression and caveolae formation were present in vascular cells, late distal convoluted tubule and principal connecting tubule and collecting duct cells of WT but not Cav1−/− kidneys. Urinary sodium excretion was increased by 94% and urine flow by 126% in Cav1−/− mice (p < 0.05). A decrease in activating phosphorylation of the Na-Cl cotransporter (NCC) of the distal convoluted tubule was recorded in Cav1−/− compared to WT kidneys (−40%; p < 0.05). Isolated intrarenal arteries from Cav1−/− mice revealed a fourfold reduction in sensitivity to phenylephrine (p < 0.05). A significantly diminished maximal contractile response (−13%; p < 0.05) was suggestive of enhanced nitric oxide (NO) availability. In line with this, the abundance of endothelial NO synthase (eNOS) was increased in Cav1−/− kidneys +213%; p < 0.05) and cultured caveolae-deprived cells showed intracellular accumulation of eNOS, compared to caveolae-intact controls. Our results suggest that renal caveolae help to conserve water and electrolytes via modulation of NCC function and regulation of vascular eNOS.
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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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8
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Mamuya FA, Xie D, Lei L, Huang M, Tsuji K, Capen DE, Yang B, Weissleder R, Păunescu TG, Lu HAJ. Deletion of β1-integrin in collecting duct principal cells leads to tubular injury and renal medullary fibrosis. Am J Physiol Renal Physiol 2017; 313:F1026-F1037. [PMID: 28701310 DOI: 10.1152/ajprenal.00038.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 06/19/2017] [Accepted: 07/11/2017] [Indexed: 11/22/2022] Open
Abstract
The renal collecting duct (CD) contains two major cell types, intercalated (ICs) and principal cells (PCs). A previous report showed that deletion of β1-integrin in the entire renal CD causes defective CD morphogenesis resulting in kidney dysfunction. However, subsequent deletion of β1-integrin specifically in ICs and PCs, respectively, did not cause any morphological defects in the CDs. The discrepancy between these studies prompts us to reinvestigate the role of β1-integrin in CD cells, specifically in the PCs. We conditionally deleted β1-integrin in mouse CD PCs using a specific aquaporin-2 (AQP2) promoter Cre-LoxP system. The resulting mutant mice, β-1f/fAQP2-Cre+, had lower body weight, failed to thrive, and died around 8-12 wk. Their CD tubules were dilated, and some of them contained cellular debris. Increased apoptosis and proliferation of PCs were observed in the dilated CDs. Trichrome staining and electron microscopy revealed the presence of peritubular and interstitial fibrosis that is associated with increased production of extracellular matrix proteins including collagen type IV and fibronectin, as detected by immunoblotting. Further analysis revealed a significantly increased expression of transforming growth factor-β (TGF-β)-induced protein, fibronectin, and TGF-β receptor-1 mRNAs and concomitantly increased phosphorylation of SMAD-2 that indicates the activation of the TGF-β signaling pathway. Therefore, our data reveal that normal expression of β1-integrin in PCs is a critical determinant of CD structural and functional integrity and further support the previously reported critical role of β1-integrin in the development and/or maintenance of the CD structure and function.
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Affiliation(s)
- Fahmy A Mamuya
- Program in Membrane Biology and Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts.,Center for Systems Biology, Massachusetts General Hospital, Boston, Massachusetts.,Harvard Medical School, Boston, Massachusetts
| | - Dongping Xie
- Program in Membrane Biology and Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts.,Center for Systems Biology, Massachusetts General Hospital, Boston, Massachusetts.,Harvard Medical School, Boston, Massachusetts.,Department of Physiology, Tongji University School of Medicine, Shanghai, China; and
| | - Lei Lei
- Program in Membrane Biology and Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts.,Center for Systems Biology, Massachusetts General Hospital, Boston, Massachusetts.,Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Ming Huang
- Program in Membrane Biology and Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts.,Center for Systems Biology, Massachusetts General Hospital, Boston, Massachusetts.,Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Kenji Tsuji
- Program in Membrane Biology and Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts.,Center for Systems Biology, Massachusetts General Hospital, Boston, Massachusetts.,Harvard Medical School, Boston, Massachusetts
| | - Diane E Capen
- Program in Membrane Biology and Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts.,Center for Systems Biology, Massachusetts General Hospital, Boston, Massachusetts
| | - BaoXue Yang
- Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Ralph Weissleder
- Center for Systems Biology, Massachusetts General Hospital, Boston, Massachusetts.,Harvard Medical School, Boston, Massachusetts
| | - Teodor G Păunescu
- Program in Membrane Biology and Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts.,Center for Systems Biology, Massachusetts General Hospital, Boston, Massachusetts.,Harvard Medical School, Boston, Massachusetts
| | - Hua A Jenny Lu
- Program in Membrane Biology and Division of Nephrology, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts; .,Center for Systems Biology, Massachusetts General Hospital, Boston, Massachusetts.,Harvard Medical School, Boston, Massachusetts
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9
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Jung HJ, Kwon TH. Molecular mechanisms regulating aquaporin-2 in kidney collecting duct. Am J Physiol Renal Physiol 2016; 311:F1318-F1328. [PMID: 27760771 DOI: 10.1152/ajprenal.00485.2016] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 10/11/2016] [Accepted: 10/11/2016] [Indexed: 01/04/2023] Open
Abstract
The kidney collecting duct is an important renal tubular segment for regulation of body water homeostasis and urine concentration. Water reabsorption in the collecting duct principal cells is controlled by vasopressin, a peptide hormone that induces the osmotic water transport across the collecting duct epithelia through regulation of water channel proteins aquaporin-2 (AQP2) and aquaporin-3 (AQP3). In particular, vasopressin induces both intracellular translocation of AQP2-bearing vesicles to the apical plasma membrane and transcription of the Aqp2 gene to increase AQP2 protein abundance. The signaling pathways, including AQP2 phosphorylation, RhoA phosphorylation, intracellular calcium mobilization, and actin depolymerization, play a key role in the translocation of AQP2. This review summarizes recent data demonstrating the regulation of AQP2 as the underlying molecular mechanism for the homeostasis of water balance in the body.
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Affiliation(s)
- Hyun Jun Jung
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and
| | - Tae-Hwan Kwon
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Taegu, Korea
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10
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Abstract
More than two dozen types of potassium channels, with different biophysical and regulatory properties, are expressed in the kidney, influencing renal function in many important ways. Recently, a confluence of discoveries in areas from human genetics to physiology, cell biology, and biophysics has cast light on the special function of five different potassium channels in the distal nephron, encoded by the genes KCNJ1, KCNJ10, KCNJ16, KCNMA1, and KCNN3. Research aimed at understanding how these channels work in health and go awry in disease has transformed our understanding of potassium balance and provided new insights into mechanisms of renal sodium handling and the maintenance of blood pressure. This review focuses on recent advances in this rapidly evolving field.
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Affiliation(s)
- Paul A Welling
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201;
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Rice WL, Li W, Mamuya F, McKee M, Păunescu TG, Lu HAJ. Polarized Trafficking of AQP2 Revealed in Three Dimensional Epithelial Culture. PLoS One 2015; 10:e0131719. [PMID: 26147297 PMCID: PMC4493001 DOI: 10.1371/journal.pone.0131719] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 06/04/2015] [Indexed: 12/21/2022] Open
Abstract
In renal collecting duct (CD) principal cells (PCs), vasopressin (VP) acts through its receptor, V2R, to increase intracellular cAMP leading to phosphorylation and apical membrane accumulation of the water channel aquaporin 2 (AQP2). The trafficking and function of basolaterally located AQP2 is, however, poorly understood. Here we report the successful application of a 3-dimensional Madin-Darby canine kidney (MDCK) epithelial model to study polarized AQP2 trafficking. This model recapitulates the luminal architecture of the CD and bi-polarized distribution of AQP2 as seen in kidney. Without stimulation, AQP2 is located in the subapical and basolateral regions. Treatment with VP, forskolin (FK), or 8-(4-Chlorophenylthio)-2′-O-methyladenosine 3′,5′-cyclic monophosphate monosodium hydrate (CPT-cAMP) leads to translocation of cytosolic AQP2 to the apical membrane, but not to the basolateral membrane. Treating cells with methyl-β-cyclodextrin (mβCD) to acutely block endocytosis causes accumulation of AQP2 on the basolateral membrane, but not on the apical membrane. Our data suggest that AQP2 may traffic differently at the apical and basolateral domains in this 3D epithelial model. In addition, application of a panel of phosphorylation specific AQP2 antibodies reveals the polarized, subcellular localization of differentially phosphorylated AQP2 at S256, S261, S264 and S269 in the 3D culture model, which is consistent with observations made in the CDs of VP treated animals, suggesting the preservation of phosphorylation dependent regulatory mechanism of AQP2 trafficking in this model. Therefore we have established a 3D culture model for the study of trafficking and regulation of both the apical and basolaterally targeted AQP2. The new model will enable further characterization of the complex mechanism regulating bi-polarized trafficking of AQP2 in vitro.
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Affiliation(s)
- William L. Rice
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, United States of America
| | - Wei Li
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, United States of America
| | - Fahmy Mamuya
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, United States of America
| | - Mary McKee
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, United States of America
| | - Teodor G. Păunescu
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, United States of America
| | - Hua A. Jenny Lu
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, United States of America
- * E-mail:
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12
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Kim S, Choi HJ, Jo CH, Park JS, Kwon TH, Kim GH. Cyclophosphamide-induced vasopressin-independent activation of aquaporin-2 in the rat kidney. Am J Physiol Renal Physiol 2015; 309:F474-83. [PMID: 26109089 DOI: 10.1152/ajprenal.00477.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 06/16/2015] [Indexed: 12/20/2022] Open
Abstract
Because cyclophosphamide-induced hyponatremia was reported to occur without changes in plasma vasopressin in a patient with central diabetes insipidus, we hypothesized that cyclophosphamide or its active metabolite, 4-hydroperoxycyclophosphamide (4-HC), may directly dysregulate the expression of water channels or sodium transporters in the kidney. To investigate whether intrarenal mechanisms for urinary concentration are activated in vivo and in vitro by treatment with cyclophosphamide and 4-HC, respectively, we used water-loaded male Sprague-Dawley rats, primary cultured inner medullary collecting duct (IMCD) cells, and IMCD suspensions prepared from male Sprague-Dawley rats. In cyclophosphamide-treated rats, significant increases in renal expression of aquaporin-2 (AQP2) and Na-K-2Cl cotransporter type 2 (NKCC2) were shown by immunoblot analysis and immunohistochemistry. Apical translocation of AQP2 was also demonstrated by quantitative immunocytochemistry. In both rat kidney and primary cultured IMCD cells, significant increases in AQP2 and vasopressin receptor type 2 (V2R) mRNA expression were demonstrated by real-time quantitative PCR analysis. Confocal laser-scanning microscopy revealed that apical translocation of AQP2 was remarkably increased when primary cultured IMCD cells were treated with 4-HC in the absence of vasopressin stimulation. Moreover, AQP2 upregulation and cAMP accumulation in response to 4-HC were significantly reduced by tolvaptan cotreatment in primary cultured IMCD cells and IMCD suspensions, respectively. We demonstrated that, in the rat kidney, cyclophosphamide may activate V2R and induce upregulation of AQP2 in the absence of vasopressin stimulation, suggesting the possibility of drug-induced nephrogenic syndrome of inappropriate antidiuresis (NSIAD).
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Affiliation(s)
- Sua Kim
- Institute of Biomedical Sciences, Hanyang University College of Medicine, Seoul, Korea
| | - Hyo-Jung Choi
- Department of Biochemistry and Cell Biology, Kyungpook National University School of Medicine, Taegu, Korea; and
| | - Chor Ho Jo
- Institute of Biomedical Sciences, Hanyang University College of Medicine, Seoul, Korea
| | - Joon-Sung Park
- Division of Nephrology, Department of Internal Medicine, Hanyang University College of Medicine, Seoul, Korea
| | - Tae-Hwan Kwon
- Department of Biochemistry and Cell Biology, Kyungpook National University School of Medicine, Taegu, Korea; and
| | - Gheun-Ho Kim
- Institute of Biomedical Sciences, Hanyang University College of Medicine, Seoul, Korea; Division of Nephrology, Department of Internal Medicine, Hanyang University College of Medicine, Seoul, Korea
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Cerqueira DM, Tran U, Romaker D, Abreu JG, Wessely O. Sterol carrier protein 2 regulates proximal tubule size in the Xenopus pronephric kidney by modulating lipid rafts. Dev Biol 2014; 394:54-64. [PMID: 25127994 DOI: 10.1016/j.ydbio.2014.07.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 05/29/2014] [Accepted: 07/30/2014] [Indexed: 11/29/2022]
Abstract
The kidney is a homeostatic organ required for waste excretion and reabsorption of water, salts and other macromolecules. To this end, a complex series of developmental steps ensures the formation of a correctly patterned and properly proportioned organ. While previous studies have mainly focused on the individual signaling pathways, the formation of higher order receptor complexes in lipid rafts is an equally important aspect. These membrane platforms are characterized by differences in local lipid and protein compositions. Indeed, the cells in the Xenopus pronephric kidney were positive for the lipid raft markers ganglioside GM1 and Caveolin-1. To specifically interfere with lipid raft function in vivo, we focused on the Sterol Carrier Protein 2 (scp2), a multifunctional protein that is an important player in remodeling lipid raft composition. In Xenopus, scp2 mRNA was strongly expressed in differentiated epithelial structures of the pronephric kidney. Knockdown of scp2 did not interfere with the patterning of the kidney along its proximo-distal axis, but dramatically decreased the size of the kidney, in particular the proximal tubules. This phenotype was accompanied by a reduction of lipid rafts, but was independent of the peroxisomal or transcriptional activities of scp2. Finally, disrupting lipid micro-domains by inhibiting cholesterol synthesis using Mevinolin phenocopied the defects seen in scp2 morphants. Together these data underscore the importance for localized signaling platforms in the proper formation of the Xenopus kidney.
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Affiliation(s)
- Débora M Cerqueira
- Cleveland Clinic Foundation, Lerner Research Institute, Department Cellular and Molecular Medicine, 9500 Euclid Avenue/NC10 Cleveland, OH 44195, USA; Universidade Federal do Rio de Janeiro, Instituto de Ciências Biomédicas-CCS, Av. Carlos Chagas Filho, 373 bloco F2 sala 15, Rio de Janeiro 21949-590, Brazil
| | - Uyen Tran
- Cleveland Clinic Foundation, Lerner Research Institute, Department Cellular and Molecular Medicine, 9500 Euclid Avenue/NC10 Cleveland, OH 44195, USA
| | - Daniel Romaker
- Cleveland Clinic Foundation, Lerner Research Institute, Department Cellular and Molecular Medicine, 9500 Euclid Avenue/NC10 Cleveland, OH 44195, USA
| | - José G Abreu
- Universidade Federal do Rio de Janeiro, Instituto de Ciências Biomédicas-CCS, Av. Carlos Chagas Filho, 373 bloco F2 sala 15, Rio de Janeiro 21949-590, Brazil
| | - Oliver Wessely
- Cleveland Clinic Foundation, Lerner Research Institute, Department Cellular and Molecular Medicine, 9500 Euclid Avenue/NC10 Cleveland, OH 44195, USA.
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