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Soleimani M. Acid base homeostasis and serum bicarbonate concentration in syndrome of inappropriate anti-diuretic hormone secretion (SIADH) with hyponatremia. Front Endocrinol (Lausanne) 2023; 14:1321338. [PMID: 38144560 PMCID: PMC10747299 DOI: 10.3389/fendo.2023.1321338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 11/16/2023] [Indexed: 12/26/2023] Open
Abstract
The Syndrome of Inappropriate ADH secretion (SIADH) presents with excess ADH release caused by a range of conditions; including pneumonia, brain tumors, certain lung cancers, and diseases of the hypothalamus. It presents with significant reduction in both sodium and chloride concentrations in the blood. However, reports examining the acid base status indicate a normal serum bicarbonate concentration and systemic acid base homeostasis. The mechanisms for the absence of abnormalities in acid base homeostasis remain speculative. This mini review is highlighting the recent advances in renal molecular physiology to provide answers for the maintenance of acid base status and serum bicarbonate in a physiological range.
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Affiliation(s)
- Manoocher Soleimani
- Department of Medicine, University of New Mexico School of Medicine, Albuquerque, NM, United States
- Research Services, New Mexico Veterans Health Care System, Albuquerque, NM, United States
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Gantsova EA, Serova OV, Eladari D, Bobrovskiy DM, Petrenko AG, Elchaninov AV, Deyev IE. A Comparative Kidney Transcriptome Analysis of Bicarbonate-Loaded insrr-Null Mice. Curr Issues Mol Biol 2023; 45:9709-9722. [PMID: 38132452 PMCID: PMC10742211 DOI: 10.3390/cimb45120606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 11/23/2023] [Accepted: 11/28/2023] [Indexed: 12/23/2023] Open
Abstract
The maintenance of plasma pH is critical for life in all organisms. The kidney plays a critical role in acid-base regulation in vertebrates by controlling the plasma concentration of bicarbonate. The receptor tyrosine kinase IRR (insulin receptor-related receptor) is expressed in renal β-intercalated cells and is involved in alkali sensing due to its ability to autophosphorylate under alkalization of extracellular medium (pH > 7.9). In mice with a knockout of the insrr gene, which encodes for IRR, urinary bicarbonate secretion in response to alkali loading is impaired. The specific regulatory mechanisms in the kidney that are under the control of IRR remain unknown. To address this issue, we analyzed and compared the kidney transcriptomes of wild-type and insrr knockout mice under basal or bicarbonate-loaded conditions. Transcriptomic analyses revealed a differential regulation of a number of genes in the kidney. Using TaqMan real-time PCR, we confirmed different expressions of the slc26a4, rps7, slc5a2, aqp6, plcd1, gapdh, rny3, kcnk5, slc6a6 and atp6v1g3 genes in IRR knockout mice. Also, we found that the expression of the kcnk5 gene is increased in wild-type mice after bicarbonate loading but not in knockout mice. Gene set enrichment analysis between the IRR knockout and wild-type samples identified that insrr knockout causes alterations in expression of genes related mostly to the ATP metabolic and electron transport chain processes.
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Affiliation(s)
- E. A. Gantsova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the RAS, Moscow 117997, Russia; (E.A.G.); (O.V.S.); (A.G.P.)
- Avtsyn Research Institute of Human Morphology of Federal State Budgetary Scientific Institution “Petrovsky National Research Centre of Surgery”, Moscow 117418, Russia;
| | - O. V. Serova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the RAS, Moscow 117997, Russia; (E.A.G.); (O.V.S.); (A.G.P.)
| | - D. Eladari
- Service de Médecine de Précision des Maladies Métaboliques et Rénales, CHU Amiens-Picardie, Université de Picardie Jules Verne, 80054 Amiens, France
| | - D. M. Bobrovskiy
- School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - A. G. Petrenko
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the RAS, Moscow 117997, Russia; (E.A.G.); (O.V.S.); (A.G.P.)
| | - A. V. Elchaninov
- Avtsyn Research Institute of Human Morphology of Federal State Budgetary Scientific Institution “Petrovsky National Research Centre of Surgery”, Moscow 117418, Russia;
| | - I. E. Deyev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the RAS, Moscow 117997, Russia; (E.A.G.); (O.V.S.); (A.G.P.)
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Soleimani M. Not all kidney cysts are created equal: a distinct renal cystogenic mechanism in tuberous sclerosis complex (TSC). Front Physiol 2023; 14:1289388. [PMID: 38028758 PMCID: PMC10663234 DOI: 10.3389/fphys.2023.1289388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 10/18/2023] [Indexed: 12/01/2023] Open
Abstract
Tuberous Sclerosis Complex (TSC) is an autosomal dominant genetic disease caused by mutations in either TSC1 or TSC2 genes. Approximately, two million individuals suffer from this disorder worldwide. TSC1 and TSC2 code for the proteins harmartin and tuberin, respectively, which form a complex that regulates the mechanistic target of rapamycin complex 1 (mTORC1) and prevents uncontrollable cell growth. In the kidney, TSC presents with the enlargement of benign tumors (angiomyolipomas) and cysts whose presence eventually causes kidney failure. The factors promoting cyst formation and tumor growth in TSC are poorly understood. Recent studies on kidney cysts in various mouse models of TSC, including mice with principal cell- or pericyte-specific inactivation of TSC1 or TSC2, have identified a unique cystogenic mechanism. These studies demonstrate the development of numerous cortical cysts that are predominantly comprised of hyperproliferating A-intercalated (A-IC) cells that express both TSC1 and TSC2. An analogous cellular phenotype in cystic epithelium is observed in both humans with TSC and in TSC2+/- mice, confirming a similar kidney cystogenesis mechanism in TSC. This cellular phenotype profoundly contrasts with kidney cysts found in Autosomal Dominant Polycystic Kidney Disease (ADPKD), which do not show any notable evidence of A-IC cells participating in the cyst lining or expansion. RNA sequencing (RNA-Seq) and confirmatory expression studies demonstrate robust expression of Forkhead Box I1 (FOXI1) transcription factor and its downstream targets, including apical H+-ATPase and cytoplasmic carbonic anhydrase 2 (CAII), in the cyst epithelia of Tsc1 (or Tsc2) knockout (KO) mice, but not in Polycystic Kidney Disease (Pkd1) mutant mice. Deletion of FOXI1, which is vital to H+-ATPase expression and intercalated (IC) cell viability, completely inhibited mTORC1 activation and abrogated the cyst burden in the kidneys of Tsc1 KO mice. These results unequivocally demonstrate the critical role that FOXI1 and A-IC cells, along with H+-ATPase, play in TSC kidney cystogenesis. This review article will discuss the latest research into the causes of kidney cystogenesis in TSC with a focus on possible therapeutic options for this devastating disease.
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Affiliation(s)
- Manoocher Soleimani
- Department of Medicine, New Mexico Veterans Health Care Center, Albuquerque, NM, United States
- Department of Medicine, University of New Mexico School of Medicine, Albuquerque, NM, United States
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Baalmann F, Brendler J, Butthof A, Popkova Y, Engel KM, Schiller J, Winter K, Lede V, Ricken A, Schöneberg T, Schulz A. Reduced urine volume and changed renal sphingolipid metabolism in P2ry14-deficient mice. Front Cell Dev Biol 2023; 11:1128456. [PMID: 37250906 PMCID: PMC10213973 DOI: 10.3389/fcell.2023.1128456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 04/28/2023] [Indexed: 05/31/2023] Open
Abstract
The UDP-glucose receptor P2RY14, a rhodopsin-like G protein-coupled receptor (GPCR), was previously described as receptor expressed in A-intercalated cells of the mouse kidney. Additionally, we found P2RY14 is abundantly expressed in mouse renal collecting duct principal cells of the papilla and epithelial cells lining the renal papilla. To better understand its physiological function in kidney, we took advantage of a P2ry14 reporter and gene-deficient (KO) mouse strain. Morphometric studies showed that the receptor function contributes to kidney morphology. KO mice had a broader cortex relative to the total kidney area than wild-type (WT) mice. In contrast, the area of the outer stripe of the outer medulla was larger in WT compared to KO mice. Transcriptome comparison of the papilla region of WT and KO mice revealed differences in the gene expression of extracellular matrix proteins (e.g., decorin, fibulin-1, fibulin-7) and proteins involved in sphingolipid metabolism (e.g., small subunit b of the serine palmitoyltransferase) and other related GPCRs (e.g., GPR171). Using mass spectrometry, changes in the sphingolipid composition (e.g., chain length) were detected in the renal papilla of KO mice. At the functional level, we found that KO mice had a reduced urine volume but an unchanged glomerular filtration rate under normal chow and salt diets. Our study revealed P2ry14 as a functionally important GPCR in collecting duct principal cells and cells lining the renal papilla and the possible involvement of P2ry14 in nephroprotection by regulation of decorin.
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Affiliation(s)
- Fabian Baalmann
- Rudolf Schönheimer Institute of Biochemistry, Faculty of Medicine, Leipzig University, Leipzig, Germany
| | - Jana Brendler
- Institute of Anatomy, Faculty of Medicine, Leipzig University, Leipzig, Germany
| | - Anne Butthof
- Rudolf Schönheimer Institute of Biochemistry, Faculty of Medicine, Leipzig University, Leipzig, Germany
| | - Yulia Popkova
- Institute of Medical Physics and Biophysics, Faculty of Medicine, Leipzig University, Leipzig, Germany
| | - Kathrin M. Engel
- Institute of Medical Physics and Biophysics, Faculty of Medicine, Leipzig University, Leipzig, Germany
| | - Jürgen Schiller
- Institute of Medical Physics and Biophysics, Faculty of Medicine, Leipzig University, Leipzig, Germany
| | - Karsten Winter
- Institute of Anatomy, Faculty of Medicine, Leipzig University, Leipzig, Germany
| | - Vera Lede
- Rudolf Schönheimer Institute of Biochemistry, Faculty of Medicine, Leipzig University, Leipzig, Germany
| | - Albert Ricken
- Institute of Anatomy, Faculty of Medicine, Leipzig University, Leipzig, Germany
| | - Torsten Schöneberg
- Rudolf Schönheimer Institute of Biochemistry, Faculty of Medicine, Leipzig University, Leipzig, Germany
| | - Angela Schulz
- Rudolf Schönheimer Institute of Biochemistry, Faculty of Medicine, Leipzig University, Leipzig, Germany
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Ferdaus MZ, Terker AS, Koumangoye R, Wall SM, Delpire E. Bicarbonate is the primary inducer of KCC3a expression in renal cortical B-type intercalated cells. Am J Physiol Cell Physiol 2023; 324:C1171-C1178. [PMID: 37036298 PMCID: PMC10191129 DOI: 10.1152/ajpcell.00094.2023] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 03/30/2023] [Accepted: 03/30/2023] [Indexed: 04/11/2023]
Abstract
A primary function of intercalated cells in the distal tubule of the kidney is to maintain pH homeostasis. For example, type B intercalated cells secrete bicarbonate largely through the action of the apical Cl-/HCO3- exchanger, pendrin, which helps correct metabolic alkalosis. Since both the K-Cl cotransporter, KCC3a and pendrin colocalize to the apical region of type B and non-A, non-B intercalated cells and since both are upregulated in models of metabolic alkalosis, such as with dietary NaHCO3 loading, we raised the possibility that apical KCC3a facilitates pendrin-mediated bicarbonate secretion, such as through apical Cl- recycling. The purpose of this study was to determine if KCC3a abundance changes through intake of bicarbonate alone or through bicarbonate plus its accompanying cation, and if it requires a direct interaction with pendrin or the renin-angiotensin-aldosterone system. We observed that KCC3a protein abundance, but not mRNA, increases in a mouse model of metabolic alkalosis, achieved with dietary NaHCO3 or KHCO3 intake. Bicarbonate ion increases KCC3a abundance, both in vivo and in vitro, independently of the accompanying cation. Moreover, bicarbonate intake upregulates KCC3a independently of aldosterone or angiotensin II. Since NaHCO3 intake increased KCC3a abundance in wild-type as well as in pendrin knockout mice, this KCC3a upregulation by bicarbonate does not depend on a direct interaction with pendrin. We conclude that increased extracellular bicarbonate, as observed in models of metabolic alkalosis, directly raises KCC3a abundance independently of angiotensin II, aldosterone, or changes in KCC3a transcription and does not involve a direct interaction with pendrin.NEW & NOTEWORTHY KCC3a expression is stimulated in alkalemia. This paper shows that bicarbonate itself is mediating this effect through a posttranscriptional mechanism. The paper also shows that this phenomenon is not mediated by aldosterone or angiotensin II.
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Affiliation(s)
- Mohammed Z Ferdaus
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Andrew S Terker
- Division of Nephrology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Rainelli Koumangoye
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Susan M Wall
- Division of Nephrology, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
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Kui M, Pluznick JL, Zaidman NA. The transcription factor Foxi1 promotes expression of V-ATPase and Gpr116 in M-1 cells. Am J Physiol Renal Physiol 2023; 324:F267-F273. [PMID: 36603001 PMCID: PMC9942906 DOI: 10.1152/ajprenal.00272.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 12/22/2022] [Accepted: 12/22/2022] [Indexed: 01/06/2023] Open
Abstract
The diverse functions of each nephron segment rely on the coordinated action of specialized cell populations that are uniquely defined by their transcriptional profile. In the collecting duct, there are two critical and distinct cell populations: principal cells and intercalated cells. Principal cells play key roles in the regulation of water, Na+, and K+, whereas intercalated cells are best known for their role in acid-base homeostasis. Currently, there are no in vitro systems that recapitulate the heterogeneity of the collecting ducts, which limits high-throughput and replicate investigations of genetic and physiological phenomena. Here, we demonstrated that the transcription factor Foxi1 is sufficient to alter the transcriptional identity of M-1 cells, a murine cortical collecting duct cell line. Specifically, overexpression of Foxi1 induces the expression of intercalated cell transcripts including Gpr116, Atp6v1b1, Atp6v1g3, Atp6v0d2, Slc4a9, and Slc26a4. These data indicate that overexpression of Foxi1 differentiates M-1 cells toward a non-A, non-B type intercalated cell phenotype and may provide a novel in vitro tool to study transcriptional regulation and physiological function of the renal collecting duct.NEW & NOTEWORTHY Transfection of M-1 cells with the transcription factor Foxi1 generates cells that express V-ATPase and Gpr116 as well as other genes associated with renal intercalated cells. This straightforward and novel in vitro system could be used to study processes including transcriptional regulation and cell specification and differentiation in renal intercalated cells.
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Affiliation(s)
- Mackenzie Kui
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Jennifer L Pluznick
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Nathan A Zaidman
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Biochemistry and Molecular Biology, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States
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Yang T. Potential of soluble (pro)renin receptor in kidney disease: can it go beyond a biomarker? Am J Physiol Renal Physiol 2022; 323:F507-F514. [PMID: 36074917 PMCID: PMC9602801 DOI: 10.1152/ajprenal.00202.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 08/25/2022] [Accepted: 08/29/2022] [Indexed: 12/14/2022] Open
Abstract
(Pro)renin receptor (PRR), also termed ATPase H+-transporting accessory protein 2 (ATP6AP2), is a type I transmembrane receptor and is capable of binding and activating prorenin and renin. Apart from its association with the renin-angiotensin system, PRR has been implicated in diverse developmental, physiological, and pathophysiological processes. Within the kidney, PRR is predominantly expressed in the distal nephron, particularly the intercalated cells, and activation of renal PRR contributes to renal injury in various rodent models of chronic kidney disease. Moreover, recent evidence demonstrates that PRR is primarily cleaved by site-1 protease to produce 28-kDa soluble PRR (sPRR). sPRR seems to mediate most of the known pathophysiological functions of renal PRR through modulating the activity of the intrarenal renin-angiotensin system and provoking proinflammatory and profibrotic responses. Not only does sPRR activate renin, but it also directly binds and activates the angiotensin II type 1 receptor. This review summarizes recent advances in understanding the roles and mechanisms of sPRR in the context of renal pathophysiology.
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Affiliation(s)
- Tianxin Yang
- Department of Internal Medicine, University of Utah and Veterans Affairs Medical Center, Salt Lake City, Utah
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Saxena V, Arregui S, Kamocka MM, Hains DS, Schwaderer A. MAP3K7 is an innate immune regulatory gene with increased expression in human and murine kidney intercalated cells following uropathogenic Escherichia coli exposure. J Cell Biochem 2022; 123:1817-1826. [PMID: 35959632 PMCID: PMC9671826 DOI: 10.1002/jcb.30318] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 05/28/2022] [Accepted: 08/01/2022] [Indexed: 01/09/2023]
Abstract
Understanding the mechanisms responsible for the kidney's defense against ascending uropathogen is critical to devise novel treatment strategies against increasingly antibiotic resistant uropathogen. Growing body of evidence indicate Intercalated cells of the kidney as the key innate immune epithelial cells against uropathogen. The aim of this study was to find orthologous and differentially expressed bacterial defense genes in human versus murine intercalated cells. We simultaneously analyzed 84 antibacterial genes in intercalated cells enriched from mouse and human kidney samples. Intercalated cell "reporter mice" were exposed to saline versus uropathogenic Escherichia coli (UPEC) transurethrally for 1 h in vivo, and intercalated cells were flow sorted. Human kidney intercalated cells were enriched from kidney biopsy using magnetic-activated cell sorting and exposed to UPEC in vitro for 1 h. RT2 antibacterial PCR array was performed. Mitogen-activated protein kinase kinase kinase 7 (MAP3K7) messenger RNA (mRNA) expression increased in intercalated cells of both humans and mice following UPEC exposure. Intercalated cell MAP3K7 protein expression was defined by immunofluorescence and confocal imaging analysis, was consistent with the increased MAP3K7 mRNA expression profiles defined by PCR. The presence of the orthologous innate immune gene MAP3K7/TAK1 suggests that it may be a key regulator of the intercalated cell antibacterial response and demands further investigation of its role in urinary tract infection pathogenesis.
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Affiliation(s)
- Vijay Saxena
- Department of Pediatric NephrologyIndiana University School of MedicineIndianapolisIndianaUSA
| | - Samuel Arregui
- Department of Pediatric NephrologyIndiana University School of MedicineIndianapolisIndianaUSA
| | - Malgorzata Maria Kamocka
- Department of Medicine, Division of NephrologyIndiana University School of MedicineIndianapolisIndianaUSA
| | - David S. Hains
- Department of Pediatric NephrologyIndiana University School of MedicineIndianapolisIndianaUSA,Department of Pediatrics, Division of NephrologyRiley Hospital for ChildrenIndianapolisIndianaUSA
| | - Andrew Schwaderer
- Department of Pediatric NephrologyIndiana University School of MedicineIndianapolisIndianaUSA,Department of Pediatrics, Division of NephrologyRiley Hospital for ChildrenIndianapolisIndianaUSA
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Xu J, Barone S, Varasteh Kia M, Holliday LS, Zahedi K, Soleimani M. Identification of IQGAP1 as a SLC26A4 (Pendrin)-Binding Protein in the Kidney. Front Mol Biosci 2022; 9:874186. [PMID: 35601831 PMCID: PMC9117723 DOI: 10.3389/fmolb.2022.874186] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 03/22/2022] [Indexed: 11/25/2022] Open
Abstract
Background: Several members of the SLC26A family of transporters, including SLC26A3 (DRA), SLC26A5 (prestin), SLC26A6 (PAT-1; CFEX) and SLC26A9, form multi-protein complexes with a number of molecules (e.g., cytoskeletal proteins, anchoring or adaptor proteins, cystic fibrosis transmembrane conductance regulator, and protein kinases). These interactions provide regulatory signals for these molecules. However, the identity of proteins that interact with the Cl-/HCO3 - exchanger, SLC26A4 (pendrin), have yet to be determined. The purpose of this study is to identify the protein(s) that interact with pendrin. Methods: A yeast two hybrid (Y2H) system was employed to screen a mouse kidney cDNA library using the C-terminal fragment of SLC26A4 as bait. Immunofluorescence microscopic examination of kidney sections, as well as co-immunoprecipitation assays, were performed using affinity purified antibodies and kidney protein extracts to confirm the co-localization and interaction of pendrin and the identified binding partners. Co-expression studies were carried out in cultured cells to examine the effect of binding partners on pendrin trafficking and activity. Results: The Y2H studies identified IQ motif-containing GTPase-activating protein 1 (IQGAP1) as a protein that binds to SLC26A4's C-terminus. Co-immunoprecipitation experiments using affinity purified anti-IQGAP1 antibodies followed by western blot analysis of kidney protein eluates using pendrin-specific antibodies confirmed the interaction of pendrin and IQGAP1. Immunofluorescence microscopy studies demonstrated that IQGAP1 co-localizes with pendrin on the apical membrane of B-intercalated cells, whereas it shows basolateral expression in A-intercalated cells in the cortical collecting duct (CCD). Functional and confocal studies in HEK-293 cells, as well as confocal studies in MDCK cells, demonstrated that the co-transfection of pendrin and IQGAP1 shows strong co-localization of the two molecules on the plasma membrane along with enhanced Cl-/HCO3 - exchanger activity. Conclusion: IQGAP1 was identified as a protein that binds to the C-terminus of pendrin in B-intercalated cells. IQGAP1 co-localized with pendrin on the apical membrane of B-intercalated cells. Co-expression of IQGAP1 with pendrin resulted in strong co-localization of the two molecules and increased the activity of pendrin in the plasma membrane in cultured cells. We propose that pendrin's interaction with IQGAP1 may play a critical role in the regulation of CCD function and physiology, and that disruption of this interaction could contribute to altered pendrin trafficking and/or activity in pathophysiologic states.
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Affiliation(s)
- Jie Xu
- Research Services, VA Medical Center, Albuquerque, NM, United States,Department of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Sharon Barone
- Research Services, VA Medical Center, Albuquerque, NM, United States,Department of Medicine, University of Cincinnati, Cincinnati, OH, United States,Department of Medicine, University of New Mexico, Albuquerque, NM, United States
| | - Mujan Varasteh Kia
- Department of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - L. Shannon Holliday
- Department of Orthodontics, University of Florida, Gainesville, FL, United States
| | - Kamyar Zahedi
- Research Services, VA Medical Center, Albuquerque, NM, United States,Department of Medicine, University of Cincinnati, Cincinnati, OH, United States,Department of Medicine, University of New Mexico, Albuquerque, NM, United States
| | - Manoocher Soleimani
- Research Services, VA Medical Center, Albuquerque, NM, United States,Department of Medicine, University of Cincinnati, Cincinnati, OH, United States,Department of Medicine, University of New Mexico, Albuquerque, NM, United States,*Correspondence: Manoocher Soleimani,
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10
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Vulinović MP, Turčić P, Micek V, Ljubojević M. Light and heavy ferritin chain expression in the liver and kidneys of Wistar rats: aging, sex differences, and impact of gonadectomy. Arh Hig Rada Toksikol 2022; 73:48-61. [PMID: 35390238 DOI: 10.2478/aiht-2022-73-3621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 03/01/2022] [Indexed: 12/02/2022] Open
Abstract
Ferritin is the main intracellular storage of iron. Animal studies show that female liver and kidney express more ferritin and accumulate more iron than male. However, no study so far has investigated sex and age differences in light (FtL) and heavy (FtH) ferritin chain expression. To address this, we relied on specific antibodies and immunochemical methods to analyse the expression of both ferritin chains in the liver and kidney of 3-month and 2-year-old male and female Wistar rats. To see how sex hormones may affect expression we also studied adult animals gonadectomised at the age of 10 weeks. FtL and FtH were more expressed in both organs of female rats, while gonadectomy increased the expression in males and decreased it in females, which suggests that it is stimulated by female and inhibited by male steroid hormones. Normal kidney ferritin distribution and change with aging warrant more attention in studies of (patho) physiological and toxicological processes.
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11
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Ray EC, Carrisoza-Gaytan R, Al-Bataineh M, Marciszyn AL, Nkashama LJ, Chen J, Winfrey A, Griffiths S, Lam TR, Flores D, Wu P, Wang W, Huang CL, Subramanya AR, Kleyman TR, Satlin LM. L-WNK1 is required for BK channel activation in intercalated cells. Am J Physiol Renal Physiol 2021; 321:F245-F254. [PMID: 34229479 PMCID: PMC8424664 DOI: 10.1152/ajprenal.00472.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 07/01/2021] [Accepted: 07/01/2021] [Indexed: 12/17/2022] Open
Abstract
Large-conductance K+ (BK) channels expressed in intercalated cells (ICs) in the aldosterone-sensitive distal nephron (ASDN) mediate flow-induced K+ secretion. In the ASDN of mice and rabbits, IC BK channel expression and activity increase with a high-K+ diet. In cell culture, the long isoform of with-no-lysine kinase 1 (L-WNK1) increases BK channel expression and activity. Apical L-WNK1 expression is selectively enhanced in ICs in the ASDN of rabbits on a high-K+ diet, suggesting that L-WNK1 contributes to BK channel regulation by dietary K+. We examined the role of IC L-WNK1 expression in enhancing BK channel activity in response to a high-K+ diet. Mice with IC-selective deletion of L-WNK1 (IC-L-WNK1-KO) and littermate control mice were placed on a high-K+ (5% K+, as KCl) diet for 10 or more days. IC-L-WNK1-KO mice exhibited reduced IC apical + subapical α-subunit expression and BK channel-dependent whole cell currents compared with controls. Six-hour urinary K+ excretion in response a saline load was similar in IC-L-WNK1-KO mice and controls. The observations that IC-L-WNK1-KO mice on a high-K+ diet have higher blood K+ concentration and reduced IC BK channel activity are consistent with impaired urinary K+ secretion, demonstrating that IC L-WNK1 has a role in the renal adaptation to a high-K+ diet.NEW & NOTEWORTHY When mice are placed on a high-K+ diet, genetic disruption of the long form of with no lysine kinase 1 (L-WNK1) in intercalated cells reduced relative apical + subapical localization of the large-conductance K+ channel, blunted large-conductance K+ channel currents in intercalated cells, and increased blood K+ concentration. These data confirm an in vivo role of L-WNK1 in intercalated cells in adaptation to a high-K+ diet.
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Affiliation(s)
- Evan C Ray
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | | | | | | | - Lubika J Nkashama
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Jingxin Chen
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Aaliyah Winfrey
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Shawn Griffiths
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Tracey R Lam
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Daniel Flores
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Peng Wu
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - WenHui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Chou-Long Huang
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Arohan R Subramanya
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Thomas R Kleyman
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Lisa M Satlin
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York
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12
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Barone S, Zahedi K, Brooks M, Henske EP, Yang Y, Zhang E, Bissler JJ, Yu JJ, Soleimani M. Kidney intercalated cells and the transcription factor FOXi1 drive cystogenesis in tuberous sclerosis complex. Proc Natl Acad Sci U S A 2021; 118:e2020190118. [PMID: 33536341 DOI: 10.1073/pnas.2020190118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is caused by mutations in TSC1 or TSC2 gene and affects multiple organs, including the kidney, where it presents with angiomyolipomata and cysts that can result in kidney failure. The factors promoting cyst formation and tumor growth in TSC are incompletely understood. Current studies demonstrate that kidney cyst epithelia in TSC mouse models and in humans with TSC are composed of hyperproliferating intercalated cells, along with activation of H+-ATPase and carbonic anhydrase 2. Interfering with intercalated cell proliferation completely inhibited and inactivating carbonic anhydrase 2 significantly protected against cyst formation in TSC. Targeting the acid base and/or electrolyte transporters of intercalated cells may provide a therapeutic approach for the treatment of kidney cysts in TSC. Tuberous sclerosis complex (TSC) is caused by mutations in either TSC1 or TSC2 genes and affects multiple organs, including kidney, lung, and brain. In the kidney, TSC presents with the enlargement of benign tumors (angiomyolipomata) and cysts, which eventually leads to kidney failure. The factors promoting cyst formation and tumor growth in TSC are incompletely understood. Here, we report that mice with principal cell-specific inactivation of Tsc1 develop numerous cortical cysts, which are overwhelmingly composed of hyperproliferating A-intercalated (A-IC) cells. RNA sequencing and confirmatory expression studies demonstrated robust expression of Forkhead Transcription Factor 1 (Foxi1) and its downstream targets, apical H+-ATPase and cytoplasmic carbonic anhydrase 2 (CAII), in cyst epithelia in Tsc1 knockout (KO) mice but not in Pkd1 mutant mice. In addition, the electrogenic 2Cl−/H+ exchanger (CLC-5) is significantly up-regulated and shows remarkable colocalization with H+-ATPase on the apical membrane of cyst epithelia in Tsc1 KO mice. Deletion of Foxi1, which is vital to intercalated cells viability and H+-ATPase expression, completely abrogated the cyst burden in Tsc1 KO mice, as indicated by MRI images and histological analysis in kidneys of Foxi1/Tsc1 double-knockout (dKO) mice. Deletion of CAII, which is critical to H+-ATPase activation, caused significant reduction in cyst burden and increased life expectancy in CAII/Tsc1 dKO mice vs. Tsc1 KO mice. We propose that intercalated cells and their acid/base/electrolyte transport machinery (H+-ATPase/CAII/CLC-5) are critical to cystogenesis, and their inhibition or inactivation is associated with significant protection against cyst generation and/or enlargement in TSC.
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13
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Asede D, Doddapaneni D, Chavez A, Okoh J, Ali S, Von-Walter C, Bolton MM. Apical intercalated cell cluster: A distinct sensory regulator in the amygdala. Cell Rep 2021; 35:109151. [PMID: 34010641 DOI: 10.1016/j.celrep.2021.109151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 02/20/2021] [Accepted: 04/23/2021] [Indexed: 12/13/2022] Open
Abstract
GABAergic neurons regulate different aspects of information processing in the amygdala. Among these are clusters of intercalated cells (ITCs), which have been implicated in fear-related behaviors. Although a few of the ITC clusters have been studied, the functional role of apical ITCs (apITCs) is unknown. Here, we combine monosynaptic rabies tracing with optogenetics and demonstrate that apITCs receive synaptic input from medial geniculate nucleus (MGm), posterior intralaminar nucleus (PIN), and medial dorsal nucleus of the thalamus and from a diverse range of cortical areas including temporal association, entorhinal, insular, piriform, and somatosensory cortex. Upon fear learning, PIN/MGm inputs are strengthened, indicative of their involvement in fear behaviors. 3-D reconstruction of apITCs reveals local arborization and innervation of the dorsal striatum and lateral amygdala. We further show that apITCs provide sensory feedforward inhibition to LA principal cells, a putative mechanism for controlling plasticity during fear learning.
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14
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Wall SM, Verlander JW, Romero CA. The Renal Physiology of Pendrin-Positive Intercalated Cells. Physiol Rev 2020; 100:1119-1147. [PMID: 32347156 PMCID: PMC7474261 DOI: 10.1152/physrev.00011.2019] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 11/06/2019] [Accepted: 11/12/2019] [Indexed: 12/13/2022] Open
Abstract
Intercalated cells (ICs) are found in the connecting tubule and the collecting duct. Of the three IC subtypes identified, type B intercalated cells are one of the best characterized and known to mediate Cl- absorption and HCO3- secretion, largely through the anion exchanger pendrin. This exchanger is thought to act in tandem with the Na+-dependent Cl-/HCO3- exchanger, NDCBE, to mediate net NaCl absorption. Pendrin is stimulated by angiotensin II and aldosterone administration via the angiotensin type 1a and the mineralocorticoid receptors, respectively. It is also stimulated in models of metabolic alkalosis, such as with NaHCO3 administration. In some rodent models, pendrin-mediated HCO3- secretion modulates acid-base balance. However, of probably more physiological or clinical significance is the role of these pendrin-positive ICs in blood pressure regulation, which occurs, at least in part, through pendrin-mediated renal Cl- absorption, as well as their effect on the epithelial Na+ channel, ENaC. Aldosterone stimulates ENaC directly through principal cell mineralocorticoid hormone receptor (ligand) binding and also indirectly through its effect on pendrin expression and function. In so doing, pendrin contributes to the aldosterone pressor response. Pendrin may also modulate blood pressure in part through its action in the adrenal medulla, where it modulates the release of catecholamines, or through an indirect effect on vascular contractile force. In addition to its role in Na+ and Cl- balance, pendrin affects the balance of other ions, such as K+ and I-. This review describes how aldosterone and angiotensin II-induced signaling regulate pendrin and the contribution of pendrin-positive ICs in the kidney to distal nephron function and blood pressure.
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Affiliation(s)
- Susan M Wall
- Departments of Medicine and Physiology, Emory University School of Medicine, Atlanta, Georgia; and Department of Medicine, University of Florida, Gainesville, Florida
| | - Jill W Verlander
- Departments of Medicine and Physiology, Emory University School of Medicine, Atlanta, Georgia; and Department of Medicine, University of Florida, Gainesville, Florida
| | - Cesar A Romero
- Departments of Medicine and Physiology, Emory University School of Medicine, Atlanta, Georgia; and Department of Medicine, University of Florida, Gainesville, Florida
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15
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Zaika O, Tomilin VN, Pochynyuk O. Adenosine inhibits the basolateral Cl - ClC-K2/b channel in collecting duct intercalated cells. Am J Physiol Renal Physiol 2020; 318:F870-F877. [PMID: 31984792 DOI: 10.1152/ajprenal.00572.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Adenosine plays an important role in various aspects of kidney physiology, but the specific targets and mechanisms of actions are not completely understood. The collecting duct has the highest expression of adenosine receptors, particularly adenosine A1 receptors (A1Rs). Interstitial adenosine levels are greatly increased up to a micromolar range in response to dietary salt loading. We have previously shown that the basolateral membrane of principal cells has primarily K+ conductance mediated by Kir4.1/5.1 channels to mediate K+ recycling and to set up a favorable driving force for Na+/K+ exchange (47). Intercalated cells express the Cl- ClC-K2/b channel mediating transcellular Cl- reabsorption. Using patch-clamp electrophysiology in freshly isolated mouse collecting ducts, we found that acute application of adenosine reversely inhibits ClC-K2/b open probability from 0.31 ± 0.04 to 0.17 ± 0.06 and to 0.10 ± 0.05 for 1 and 10 µM, respectively. In contrast, adenosine (10 µM) had no measureable effect on Kir4.1/5.1 channel activity in principal cells. The inhibitory effect of adenosine on ClC-K2/b was abolished in the presence of the A1R blocker 8-cyclopentyl-1,3-dipropylxanthine (10 µM). Consistently, application of the A1R agonist N6-cyclohexyladenosine (1 µM) recapitulated the inhibitory action of adenosine on ClC-K2/b open probability. The effects of adenosine signaling in the collecting duct were independent from its purinergic counterpartner, ATP, having no measurable actions on ClC-K2/b and Kir4.1/5.1. Overall, we demonstrated that adenosine selectively inhibits ClC-K2/b activity in intercalated cells by targeting A1Rs. We propose that inhibition of transcellular Cl- reabsorption in the collecting duct by adenosine would aid in augmenting NaCl excretion during high salt intake.
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Affiliation(s)
- Oleg Zaika
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas
| | - Viktor N Tomilin
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas
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16
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Shen T, Levitman A, Li Y, Jacobs M, Xu K, Barasch J. Urinary defense begins in the kidney. Kidney Int 2019; 96:537-539. [PMID: 31445577 DOI: 10.1016/j.kint.2019.03.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 03/22/2019] [Indexed: 11/19/2022]
Affiliation(s)
- Tian Shen
- Columbia University, Department of Medicine, New York, New York, USA
| | - Abraham Levitman
- Columbia University, Department of Medicine, New York, New York, USA
| | - Yuanji Li
- Columbia University, Department of Medicine, New York, New York, USA
| | - Mendel Jacobs
- Columbia University, Department of Medicine, New York, New York, USA
| | - Katherine Xu
- Columbia University, Department of Medicine, New York, New York, USA
| | - Jonathan Barasch
- Columbia University, Department of Medicine, New York, New York, USA.
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17
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Eichler T, Bender K, Murtha MJ, Schwartz L, Metheny J, Solden L, Jaggers RM, Bailey MT, Gupta S, Mosquera C, Ching C, La Perle K, Li B, Becknell B, Spencer JD. Ribonuclease 7 Shields the Kidney and Bladder from Invasive Uropathogenic Escherichia coli Infection. J Am Soc Nephrol 2019; 30:1385-1397. [PMID: 31239387 DOI: 10.1681/asn.2018090929] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 04/17/2019] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Evidence suggests that antimicrobial peptides, components of the innate immune response, protect the kidneys and bladder from bacterial challenge. We previously identified ribonuclease 7 (RNase 7) as a human antimicrobial peptide that has bactericidal activity against uropathogenic Escherichia coli (UPEC). Functional studies assessing RNase 7's contributions to urinary tract defense are limited. METHODS To investigate RNase 7's role in preventing urinary tract infection (UTI), we quantified urinary RNase 7 concentrations in 29 girls and adolescents with a UTI history and 29 healthy female human controls. To assess RNase 7's antimicrobial activity in vitro in human urothelial cells, we used siRNA to silence urothelial RNase 7 production and retroviral constructs to stably overexpress RNase 7; we then evaluated UPEC's ability to bind and invade these cells. For RNase 7 in vivo studies, we developed humanized RNase 7 transgenic mice, subjected them to experimental UTI, and enumerated UPEC burden in the urine, bladder, and kidneys. RESULTS Compared with controls, study participants with a UTI history had 1.5-fold lower urinary RNase 7 concentrations. When RNase 7 was silenced in vitro, the percentage of UPEC binding or invading human urothelial cells increased; when cells overexpressed RNase 7, UPEC attachment and invasion decreased. In the transgenic mice, we detected RNase 7 expression in the kidney's intercalated cells and bladder urothelium. RNase 7 humanized mice exhibited marked protection from UPEC. CONCLUSIONS These findings provide evidence that RNase 7 has a role in kidney and bladder host defense against UPEC and establish a foundation for investigating RNase 7 as a UTI prognostic marker or nonantibiotic-based therapy.
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Affiliation(s)
- Tad Eichler
- Centers for Clinical and Translational Research and.,Nephrology and Urology Research Affinity Group
| | - Kristin Bender
- Centers for Clinical and Translational Research and.,Nephrology and Urology Research Affinity Group
| | - Matthew J Murtha
- Centers for Clinical and Translational Research and.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio; and
| | - Laura Schwartz
- Centers for Clinical and Translational Research and.,Nephrology and Urology Research Affinity Group
| | | | - Lindsey Solden
- Microbial Pathogenesis, The Research Institute at Nationwide Children's, Columbus, Ohio
| | - Robert M Jaggers
- Microbial Pathogenesis, The Research Institute at Nationwide Children's, Columbus, Ohio
| | - Michael T Bailey
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio; and.,Microbial Pathogenesis, The Research Institute at Nationwide Children's, Columbus, Ohio
| | - Sudipti Gupta
- Centers for Clinical and Translational Research and.,Nephrology and Urology Research Affinity Group
| | | | - Christina Ching
- Centers for Clinical and Translational Research and.,Nephrology and Urology Research Affinity Group.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio; and.,Divisions of Urology and.,Departments of Pediatric Surgery and
| | - Krista La Perle
- Comparative Pathology and Mouse Phenotyping Shared Resource, The Ohio State University College of Veterinary Medicine, Columbus, Ohio
| | - Birong Li
- Centers for Clinical and Translational Research and
| | - Brian Becknell
- Centers for Clinical and Translational Research and.,Nephrology and Urology Research Affinity Group.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio; and.,Nephrology, and.,Pediatrics, Nationwide Children's, Columbus, Ohio
| | - John David Spencer
- Centers for Clinical and Translational Research and .,Nephrology and Urology Research Affinity Group.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio; and.,Nephrology, and.,Pediatrics, Nationwide Children's, Columbus, Ohio
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18
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Elitok S, Sidler M, Bieringer M, Mohebbi N, Schneider W, Wagner CA. A patient with chronic kidney disease, primary biliary cirrhosis and metabolic acidosis. Clin Kidney J 2019; 13:463-467. [PMID: 32699627 PMCID: PMC7367120 DOI: 10.1093/ckj/sfz059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 04/17/2019] [Indexed: 11/14/2022] Open
Abstract
Autoimmune disorders such as rheumatoid arthritis or Sjögren's syndrome can be associated with impaired renal acid excretion. Only few cases of patients with primary biliary cirrhosis (PBC) and distal renal tubular acidosis (dRTA) have been described. Here, we present the case of a 60-year-old woman with PBC and dRTA. Her kidney biopsy showed an absence of markers of acid-secretory Type A intercalated cells (A-ICs) and expression of aquaporin-2, a marker of principal cells, in all cells lining the collecting duct. Moreover, the serum of the patient contained antibodies directed against a subset of cells of the collecting duct. Thus, PBC-related autoantibodies may target acid-secretory A-ICs and thereby impair urinary acidification.
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Affiliation(s)
- Saban Elitok
- Department of Nephrology and Endocrinology/Diabetology, Klinikum Ernst von Bergmann, Potsdam, Germany
- Correspondence and offprint requests to: Saban Elitok; E-mail: , Carsten A. Wagner; E-mail:
| | - Marius Sidler
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | | | - Nilufar Mohebbi
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | | | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Correspondence and offprint requests to: Saban Elitok; E-mail: , Carsten A. Wagner; E-mail:
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19
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Shibata S. Role of Pendrin in the Pathophysiology of Aldosterone-Induced Hypertension. Am J Hypertens 2019; 32:607-613. [PMID: 30982848 DOI: 10.1093/ajh/hpz054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 04/11/2019] [Indexed: 11/14/2022] Open
Abstract
The recent advances in genetics and molecular biology have resulted in the characterization of key components that critically regulate renal NaCl transport and blood pressure. Pendrin is a Cl-/HCO3- exchanger that is highly expressed in thyroid, inner ear, and kidney. In the kidney, it is selectively present at the apical membrane in non-α intercalated cells of the connecting tubules and cortical collecting duct. Besides its role in acid/base homeostasis, accumulating studies using various genetically modified animals have provided compelling evidence that pendrin regulates extracellular fluid volume and electrolyte balance at the downstream of aldosterone signaling. We have shown that angiotensin II and aldosterone cooperatively control pendrin abundance partly through mammalian target of rapamycin signaling and mineralocorticoid receptor dephosphorylation, which is necessary for the kidney to prevent extracellular fluid loss and electrolyte disturbances under physiologic perturbations. In line with the experimental observations, several clinical data indicated that the impaired pendrin function can cause fluid and electrolyte abnormalities in humans. The purpose of this review is to provide an update on the recent progress regarding the role of pendrin in fluid and electrolyte homeostasis, as well as in the pathophysiology of hypertension associated with mineralocorticoid receptor signaling.
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Affiliation(s)
- Shigeru Shibata
- Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan
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20
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Giesecke T, Himmerkus N, Leipziger J, Bleich M, Koshimizu TA, Fähling M, Smorodchenko A, Shpak J, Knappe C, Isermann J, Ayasse N, Kawahara K, Schmoranzer J, Gimber N, Paliege A, Bachmann S, Mutig K. Vasopressin Increases Urinary Acidification via V1a Receptors in Collecting Duct Intercalated Cells. J Am Soc Nephrol 2019; 30:946-961. [PMID: 31097611 DOI: 10.1681/asn.2018080816] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 03/11/2019] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND Antagonists of the V1a vasopressin receptor (V1aR) are emerging as a strategy for slowing progression of CKD. Physiologically, V1aR signaling has been linked with acid-base homeostasis, but more detailed information is needed about renal V1aR distribution and function. METHODS We used a new anti-V1aR antibody and high-resolution microscopy to investigate Va1R distribution in rodent and human kidneys. To investigate whether V1aR activation promotes urinary H+ secretion, we used a V1aR agonist or antagonist to evaluate V1aR function in vasopressin-deficient Brattleboro rats, bladder-catheterized mice, isolated collecting ducts, and cultured inner medullary collecting duct (IMCD) cells. RESULTS Localization of V1aR in rodent and human kidneys produced a basolateral signal in type A intercalated cells (A-ICs) and a perinuclear to subapical signal in type B intercalated cells of connecting tubules and collecting ducts. Treating vasopressin-deficient Brattleboro rats with a V1aR agonist decreased urinary pH and tripled net acid excretion; we observed a similar response in C57BL/6J mice. In contrast, V1aR antagonist did not affect urinary pH in normal or acid-loaded mice. In ex vivo settings, basolateral treatment of isolated perfused medullary collecting ducts with the V1aR agonist or vasopressin increased intracellular calcium levels in ICs and decreased luminal pH, suggesting V1aR-dependent calcium release and stimulation of proton-secreting proteins. Basolateral treatment of IMCD cells with the V1aR agonist increased apical abundance of vacuolar H+-ATPase in A-ICs. CONCLUSIONS Our results show that activation of V1aR contributes to urinary acidification via H+ secretion by A-ICs, which may have clinical implications for pharmacologic targeting of V1aR.
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Affiliation(s)
- Torsten Giesecke
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; .,Berlin Institute of Health (BIH), Berlin, Germany
| | - Nina Himmerkus
- Institute of Physiology, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Jens Leipziger
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Markus Bleich
- Institute of Physiology, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Taka-Aki Koshimizu
- Division of Molecular Pharmacology, Department of Pharmacology, Jichi Medical University, Shimotsuke-shi, Tochigi-ken, Japan
| | - Michael Fähling
- Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Alina Smorodchenko
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Julia Shpak
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Carolin Knappe
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Julian Isermann
- Institute of Physiology, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Niklas Ayasse
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Katsumasa Kawahara
- Department of Physiology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Jan Schmoranzer
- Advanced Medical BioImaging Core Facility, Charite-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Niclas Gimber
- Advanced Medical BioImaging Core Facility, Charite-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Alexander Paliege
- Division of Nephrology, Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany; and
| | - Sebastian Bachmann
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Kerim Mutig
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; .,Department of Pharmacology, I.M. Sechenov First Moscow State Medical University of the Ministry of Healthcare of the Russian Federation (Sechenovskiy University), Moscow, Russian Federation
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21
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Tomilin V, Mamenko M, Zaika O, Wingo CS, Pochynyuk O. TRPV4 deletion protects against hypokalemia during systemic K + deficiency. Am J Physiol Renal Physiol 2019; 316:F948-F956. [PMID: 30838874 DOI: 10.1152/ajprenal.00043.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Tight regulation of K+ balance is fundamental for normal physiology. Reduced dietary K+ intake, which is common in Western diets, often leads to hypokalemia and associated cardiovascular- and kidney-related pathologies. The distal nephron, and, specifically, the collecting duct (CD), is the major site of controlled K+ reabsorption via H+-K+-ATPase in the state of dietary K+ deficiency. We (Mamenko MV, Boukelmoune N, Tomilin VN, Zaika OL, Jensen VB, O'Neil RG, Pochynyuk OM. Kidney Int 91: 1398-1409, 2017) have previously demonstrated that the transient receptor potential vanilloid type 4 (TRPV4) Ca2+ channel, abundantly expressed in the CD, contributes to renal K+ handling by promoting flow-induced K+ secretion. Here, we investigated a potential role of TRPV4 in controlling H+-K+-ATPase-dependent K+ reabsorption in the CD. Treatment with a K+-deficient diet (<0.01% K+) for 7 days reduced serum K+ levels in wild-type (WT) mice from 4.3 ± 0.2 to 3.3 ± 0.2 mM but not in TRPV4-/- mice (4.3 ± 0.1 and 4.2 ± 0.3 mM, respectively). Furthermore, we detected a significant reduction in 24-h urinary K+ levels in TRPV4-/- compared with WT mice upon switching to K+-deficient diet. TRPV4-/- animals also had significantly more acidic urine on a low-K+ diet, but not on a regular (0.9% K+) or high-K+ (5% K+) diet, which is consistent with increased H+-K+-ATPase activity. Moreover, we detected a greatly accelerated H+-K+-ATPase-dependent intracellular pH extrusion in freshly isolated CDs from TRPV4-/- compared with WT mice fed a K+-deficient diet. Overall, our results demonstrate a novel kaliuretic role of TRPV4 by inhibiting H+-K+-ATPase-dependent K+ reabsorption in the CD. We propose that TRPV4 inhibition could be a novel strategy to manage certain hypokalemic states in clinical settings.
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Affiliation(s)
- Viktor Tomilin
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston , Houston, Texas
| | - Mykola Mamenko
- Department of Physiology, Medical College of Georgia, Augusta University , Augusta, Georgia
| | - Oleg Zaika
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston , Houston, Texas
| | - Charles S Wingo
- Division of Nephrology, Hypertension and Transplantation, Department of Medicine, University of Florida , Gainesville, Florida.,North Florida/South Georgia Veterans Health System, Gainesville, Florida
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston , Houston, Texas
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Yamazaki O, Ishizawa K, Hirohama D, Fujita T, Shibata S. Electrolyte transport in the renal collecting duct and its regulation by the renin-angiotensin-aldosterone system. Clin Sci (Lond) 2019; 133:75-82. [PMID: 30622159 DOI: 10.1042/CS20180194] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 11/29/2018] [Accepted: 12/17/2018] [Indexed: 01/13/2023]
Abstract
Distal nephron of the kidney plays key roles in fluid volume and electrolyte homeostasis by tightly regulating reabsorption and excretion of Na+, K+, and Cl- Studies to date demonstrate the detailed electrolyte transport mechanisms in principal cells of the cortical collecting duct, and their regulation by renin-angiotensin-aldosterone system (RAAS). In recent years, however, accumulating data indicate that intercalated cells, another cell type that is present in the cortical collecting duct, also play active roles in the regulation of blood pressure. Notably, pendrin in β-intercalated cells not only controls acid/base homeostasis, but is also one of the key components controlling salt and K+ transport in distal nephron. We have recently shown that pendrin is regulated by the co-ordinated action of angiotensin II (AngII) and aldosterone, and at the downstream of AngII, mammalian target of rapamycin (mTOR) signaling regulates pendrin through inhibiting the kinase unc51-like-kinase 1 and promoting dephosphorylation of mineralocorticoid receptor (MR). In this review, we summarize recent advances in the current knowledge on the salt transport mechanisms in the cortical collecting duct, and their regulation by the RAAS.
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23
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López-Cayuqueo KI, Chavez-Canales M, Pillot A, Houillier P, Jayat M, Baraka-Vidot J, Trepiccione F, Baudrie V, Büsst C, Soukaseum C, Kumai Y, Jeunemaître X, Hadchouel J, Eladari D, Chambrey R. A mouse model of pseudohypoaldosteronism type II reveals a novel mechanism of renal tubular acidosis. Kidney Int 2018; 94:514-523. [PMID: 30146013 DOI: 10.1016/j.kint.2018.05.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 04/26/2018] [Accepted: 05/03/2018] [Indexed: 02/04/2023]
Abstract
Pseudohypoaldosteronism type II (PHAII) is a genetic disease characterized by association of hyperkalemia, hyperchloremic metabolic acidosis, hypertension, low renin, and high sensitivity to thiazide diuretics. It is caused by mutations in the WNK1, WNK4, KLHL3 or CUL3 gene. There is strong evidence that excessive sodium chloride reabsorption by the sodium chloride cotransporter NCC in the distal convoluted tubule is involved. WNK4 is expressed not only in distal convoluted tubule cells but also in β-intercalated cells of the cortical collecting duct. These latter cells exchange intracellular bicarbonate for external chloride through pendrin, and therefore, account for renal base excretion. However, these cells can also mediate thiazide-sensitive sodium chloride absorption when the pendrin-dependent apical chloride influx is coupled to apical sodium influx by the sodium-driven chloride/bicarbonate exchanger. Here we determine whether this system is involved in the pathogenesis of PHAII. Renal pendrin activity was markedly increased in a mouse model carrying a WNK4 missense mutation (Q562E) previously identified in patients with PHAII. The upregulation of pendrin led to an increase in thiazide-sensitive sodium chloride absorption by the cortical collecting duct, and it caused metabolic acidosis. The function of apical potassium channels was altered in this model, and hyperkalemia was fully corrected by pendrin genetic ablation. Thus, we demonstrate an important contribution of pendrin in renal regulation of sodium chloride, potassium and acid-base homeostasis and in the pathophysiology of PHAII. Furthermore, we identify renal distal bicarbonate secretion as a novel mechanism of renal tubular acidosis.
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Affiliation(s)
- Karen I López-Cayuqueo
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 970, Paris, France; Centro de Estudios Científicos, Valdivia, Chile
| | - Maria Chavez-Canales
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 970, Paris, France
| | - Alexia Pillot
- Centre National de la Recherche Scientifique Equipe de Recherche Labelisée 8228, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche_S1138, Centre de Recherche des Cordeliers, Paris, France
| | - Pascal Houillier
- Centre National de la Recherche Scientifique Equipe de Recherche Labelisée 8228, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche_S1138, Centre de Recherche des Cordeliers, Paris, France; Genetics, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
| | - Maximilien Jayat
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 970, Paris, France
| | - Jennifer Baraka-Vidot
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 1188, CYROI, Sainte Clotilde, La Réunion, France
| | - Francesco Trepiccione
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 970, Paris, France
| | - Véronique Baudrie
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 970, Paris, France; Genetics, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
| | - Cara Büsst
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 970, Paris, France
| | - Christelle Soukaseum
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 970, Paris, France
| | - Yusuke Kumai
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 970, Paris, France
| | - Xavier Jeunemaître
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 970, Paris, France; Genetics, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
| | - Juliette Hadchouel
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 970, Paris, France
| | - Dominique Eladari
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 970, Paris, France; Service d'Explorations Fonctionnelles Rénales, Hôpital Felix Guyon, CHU de la Réunion, Saint Denis, La Réunion, France; Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 1188, CYROI, Sainte Clotilde, La Réunion, France.
| | - Régine Chambrey
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 970, Paris, France; Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 1188, CYROI, Sainte Clotilde, La Réunion, France; Centre National de la Recherche Scientifique, Délégation Paris Michel-Ange, Paris, France.
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24
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Nanami M, Pham TD, Kim YH, Yang B, Sutliff RL, Staub O, Klein JD, Lopez-Cayuqueo KI, Chambrey R, Park AY, Wang X, Pech V, Verlander JW, Wall SM. The Role of Intercalated Cell Nedd4-2 in BP Regulation, Ion Transport, and Transporter Expression. J Am Soc Nephrol 2018; 29:1706-1719. [PMID: 29773687 DOI: 10.1681/asn.2017080826] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 03/29/2018] [Indexed: 12/23/2022] Open
Abstract
BackgroundNedd4-2 is an E3 ubiquitin-protein ligase that associates with transport proteins, causing their ubiquitylation, and then internalization and degradation. Previous research has suggested a correlation between Nedd4-2 and BP. In this study, we explored the effect of intercalated cell (IC) Nedd4-2 gene ablation on IC transporter abundance and function and on BP.Methods We generated IC Nedd4-2 knockout mice using Cre-lox technology and produced global pendrin/Nedd4-2 null mice by breeding global Nedd4-2 null (Nedd4-2-/- ) mice with global pendrin null (Slc26a4-/- ) mice. Mice ate a diet with 1%-4% NaCl; BP was measured by tail cuff and radiotelemetry. We measured transepithelial transport of Cl- and total CO2 and transepithelial voltage in cortical collecting ducts perfused in vitro Transporter abundance was detected with immunoblots, immunohistochemistry, and immunogold cytochemistry.Results IC Nedd4-2 gene ablation markedly increased electroneutral Cl-/HCO3- exchange in the cortical collecting duct, although benzamil-, thiazide-, and bafilomycin-sensitive ion flux changed very little. IC Nedd4-2 gene ablation did not increase the abundance of type B IC transporters, such as AE4 (Slc4a9), H+-ATPase, barttin, or the Na+-dependent Cl-/HCO3- exchanger (Slc4a8). However, IC Nedd4-2 gene ablation increased CIC-5 total protein abundance, apical plasma membrane pendrin abundance, and the ratio of pendrin expression on the apical membrane to the cytoplasm. IC Nedd4-2 gene ablation increased BP by approximately 10 mm Hg. Moreover, pendrin gene ablation eliminated the increase in BP observed in global Nedd4-2 knockout mice.Conclusions IC Nedd4-2 regulates Cl-/HCO3- exchange in ICs., Nedd4-2 gene ablation increases BP in part through its action in these cells.
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Affiliation(s)
| | | | | | - Baoli Yang
- Department of Obstetrics and Gynecology, University of Iowa, Iowa City, Iowa
| | | | - Olivier Staub
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,National Centre of Competence in Research "Kidney.ch," Zurich, Switzerland
| | | | - Karen I Lopez-Cayuqueo
- Centro de Estudios Cientificos, Valdivia, Chile.,Institut National de la Santé et de la Recherche Médicale U970, Paris Cardiovascular Research Center, Université Paris-Descartes, Paris, France
| | - Regine Chambrey
- Institut National de la Santé et de la Recherche Médicale U1188, Universite de la Reunion, Plateforme Cyclotron Réunion Océan Indien, St. Denis, Ile de la Reunion, France; and
| | | | | | | | - Jill W Verlander
- Renal Division, Department of Medicine, University of Florida at Gainesville, Gainesville, Florida
| | - Susan M Wall
- Renal and .,Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
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25
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Trepiccione F, Soukaseum C, Baudrie V, Kumai Y, Teulon J, Villoutreix B, Cornière N, Wangemann P, Griffith AJ, Byung Choi Y, Hadchouel J, Chambrey R, Eladari D. Acute genetic ablation of pendrin lowers blood pressure in mice. Nephrol Dial Transplant 2018; 32:1137-1145. [PMID: 28064162 DOI: 10.1093/ndt/gfw393] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 10/02/2016] [Indexed: 11/14/2022] Open
Abstract
Background Pendrin, the chloride/bicarbonate exchanger of β-intercalated cells of the renal connecting tubule and the collecting duct, plays a key role in NaCl reabsorption by the distal nephron. Therefore, pendrin may be important for the control of extracellular fluid volume and blood pressure. Methods Here, we have used a genetic mouse model in which the expression of pendrin can be switched-on in vivo by the administration of doxycycline. Pendrin can also be rapidly removed when doxycycline administration is discontinued. Therefore, our genetic strategy allows us to test selectively the acute effects of loss of pendrin function. Results We show that acute loss of pendrin leads to a significant decrease of blood pressure. In addition, acute ablation of pendrin did not alter significantly the acid-base status or blood K + concentration. Conclusion By using a transgenic mouse model, avoiding off-target effects related to pharmacological compounds, this study suggests that pendrin could be a novel target to treat hypertension.
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Affiliation(s)
- Francesco Trepiccione
- INSERM U970, Paris Cardiovascular Research Center, Université Paris-Descartes, Paris, France
| | - Christelle Soukaseum
- INSERM U970, Paris Cardiovascular Research Center, Université Paris-Descartes, Paris, France
| | - Veronique Baudrie
- INSERM U970, Paris Cardiovascular Research Center, Université Paris-Descartes, Paris, France.,Hôpital Européen Georges Pompidou, Département de Physiologie, Assistance Publique-Hopitaux de Paris, Paris, France
| | - Yusuke Kumai
- INSERM U970, Paris Cardiovascular Research Center, Université Paris-Descartes, Paris, France
| | - Jacques Teulon
- CNRS ERL 8228, INSERM UMRS 1138, Université Pierre et Marie Curie, Centre de Recherche des Cordeliers, Paris, France
| | - Bruno Villoutreix
- INSERM U973, MTi-Bioinformatics; University Paris Diderot, Paris, France
| | - Nicolas Cornière
- Service d'Explorations Fonctionnelles Rénales, Hôpital Felix Guyon, CHU de la Réunion, St Denis, Ile de la Réunion, France
| | - Philine Wangemann
- Anatomy and Physiology Department, Kansas State University, Manhattan, KS, USA
| | - Andrew J Griffith
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Yoon Byung Choi
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Juliette Hadchouel
- INSERM U970, Paris Cardiovascular Research Center, Université Paris-Descartes, Paris, France
| | - Regine Chambrey
- INSERM U970, Paris Cardiovascular Research Center, Université Paris-Descartes, Paris, France.,Centre National de la Recherche Scientifique, Paris, France
| | - Dominique Eladari
- Service d'Explorations Fonctionnelles Rénales, Hôpital Felix Guyon, CHU de la Réunion, St Denis, Ile de la Réunion, France
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26
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Barrett DW, Gonzalez-Lima F. Prefrontal-limbic Functional Connectivity during Acquisition and Extinction of Conditioned Fear. Neuroscience 2018; 376:162-171. [PMID: 29477695 DOI: 10.1016/j.neuroscience.2018.02.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 02/12/2018] [Accepted: 02/14/2018] [Indexed: 11/17/2022]
Abstract
This study is a new analysis to obtain novel metabolic data on the functional connectivity of prefrontal-limbic regions in Pavlovian fear acquisition and extinction of tone-footshock conditioning. Mice were analyzed with the fluorodeoxyglucose (FDG) autoradiographic method to metabolically map regional brain activity. New FDG data were sampled from the nuclei of the habenula and other regions implicated in aversive conditioning, such as infralimbic cortex, amygdala and periaqueductal gray regions. The activity patterns among these regions were inter-correlated during acquisition, extinction or pseudorandom training to develop a functional connectivity model. Two subdivisions of the habenular complex showed increased activity after acquisition relative to extinction, with the pseudorandom group intermediate between the other two groups. Significant acquisition activation effects were also found in centromedial amygdala, dorsomedial and ventrolateral periaqueductal gray. FDG uptake increases during extinction were found only in dorsal and ventral infralimbic cortex. The overall pattern of activity correlations between these regions revealed extensive but differential functional connectivity during acquisition and extinction training, with less functional connectivity found after pseudorandom training. Interestingly, habenula nuclei showed a distinct pattern of inter-correlations with amygdala nuclei during extinction. The functional connectivity model revealed changing interactions among infralimbic cortex, amygdala, habenula and periaqueductal gray regions through the stages of Pavlovian fear acquisition and extinction. This study provided new data on the contributions of the habenula to fear conditioning, and revealed previously unreported infralimbic-amygdala-habenula-periaqueductal gray interactions implicated in acquisition and extinction of conditioned fear.
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Affiliation(s)
- Douglas W Barrett
- Department of Psychology and Institute for Neuroscience, University of Texas at Austin, Austin, TX 78712, USA
| | - F Gonzalez-Lima
- Department of Psychology and Institute for Neuroscience, University of Texas at Austin, Austin, TX 78712, USA.
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27
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Merkulova M, Păunescu TG, Nair AV, Wang CY, Capen DE, Oliver PL, Breton S, Brown D. Targeted deletion of the Ncoa7 gene results in incomplete distal renal tubular acidosis in mice. Am J Physiol Renal Physiol 2018; 315:F173-F185. [PMID: 29384414 DOI: 10.1152/ajprenal.00407.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We recently reported that nuclear receptor coactivator 7 (Ncoa7) is a vacuolar proton pumping ATPase (V-ATPase) interacting protein whose function has not been defined. Ncoa7 is highly expressed in the kidney and partially colocalizes with the V-ATPase in collecting duct intercalated cells (ICs). Here, we hypothesized that targeted deletion of the Ncoa7 gene could affect V-ATPase activity in ICs in vivo. We tested this by analyzing the acid-base status, major electrolytes, and kidney morphology of Ncoa7 knockout (KO) mice. We found that Ncoa7 KO mice, similar to Atp6v1b1 KOs, did not develop severe distal renal tubular acidosis (dRTA), but they exhibited a persistently high urine pH and developed hypobicarbonatemia after acid loading with ammonium chloride. Conversely, they did not develop significant hyperbicarbonatemia and alkalemia after alkali loading with sodium bicarbonate. We also found that ICs were larger and with more developed apical microvilli in Ncoa7 KO compared with wild-type mice, a phenotype previously associated with metabolic acidosis. At the molecular level, the abundance of several V-ATPase subunits, carbonic anhydrase 2, and the anion exchanger 1 was significantly reduced in medullary ICs of Ncoa7 KO mice, suggesting that Ncoa7 is important for maintaining high levels of these proteins in the kidney. We conclude that Ncoa7 is involved in IC function and urine acidification in mice in vivo, likely through modulating the abundance of V-ATPase and other key acid-base regulators in the renal medulla. Consequently, mutations in the NCOA7 gene may also be involved in dRTA pathogenesis in humans.
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Affiliation(s)
- Maria Merkulova
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
| | - Teodor G Păunescu
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
| | - Anil V Nair
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
| | - Chia-Yu Wang
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
| | - Diane E Capen
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
| | - Peter L Oliver
- Department of Physiology, Anatomy and Genetics, University of Oxford , Oxford , United Kingdom
| | - Sylvie Breton
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
| | - Dennis Brown
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
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28
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Assmus AM, Mansley MK, Mullins LJ, Peter A, Mullins JJ. mCCD cl1 cells show plasticity consistent with the ability to transition between principal and intercalated cells. Am J Physiol Renal Physiol 2017; 314:F820-F831. [PMID: 29357433 DOI: 10.1152/ajprenal.00354.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The cortical collecting duct of the mammalian kidney plays a critical role in the regulation of body volume, sodium pH, and osmolarity and is composed of two distinct cells types, principal cells and intercalated cells. Each cell type is detectable in the kidney by the localization of specific transport proteins such as aquaporin 2 (Aqp2) and epithelial sodium channel (ENaC) in principal cells and V-ATPase B1 and connexin 30 (Cx30) in intercalated cells. mCCDcl1 cells have been widely used as a mouse principal cell line on the basis of their physiological characteristics. In this study, the mCCDcl1 parental cell line and three sublines cloned from isolated single cells (Ed1, Ed2, and Ed3) were grown on filters to assess their transepithelial resistance, transepithelial voltage, equivalent short circuit current and expression of the cell-specific markers Aqp2, ENaC, V-ATPaseB1, and Cx30. The parental mCCDcl1 cell line presented amiloride-sensitive electrogenic sodium transport indicative of principal cell function; however, immunocytochemistry and RT-PCR showed that some cells expressed the intercalated cell-specific markers V-ATPase B1 and Cx30, including a subset of cells also positive for Aqp2 and ENaC. The three subclonal lines contained cells that were positive for both intercalated and principal cell-specific markers. The vertical transmission of both principal and intercalated cell characteristics via single cell cloning reveals the plasticity of mCCDcl1 cells and a direct lineage relationship between these two physiologically important cell types and is consistent with mCCDcl1 cells being precursor cells.
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Affiliation(s)
- A M Assmus
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh , Edinburgh , United Kingdom
| | - M K Mansley
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh , Edinburgh , United Kingdom
| | - L J Mullins
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh , Edinburgh , United Kingdom
| | - A Peter
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh , Edinburgh , United Kingdom
| | - J J Mullins
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh , Edinburgh , United Kingdom
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29
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Battistone MA, Nair AV, Barton CR, Liberman RN, Peralta MA, Capen DE, Brown D, Breton S. Extracellular Adenosine Stimulates Vacuolar ATPase-Dependent Proton Secretion in Medullary Intercalated Cells. J Am Soc Nephrol 2017; 29:545-556. [PMID: 29222395 DOI: 10.1681/asn.2017060643] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 10/18/2017] [Indexed: 12/29/2022] Open
Abstract
Acidosis is an important complication of AKI and CKD. Renal intercalated cells (ICs) express the proton pumping vacuolar H+-ATPase (V-ATPase) and are extensively involved in acid-base homeostasis. H+ secretion in type A intercalated cells (A-ICs) is regulated by apical vesicle recycling and stimulated by cAMP. In other cell types, cAMP is increased by extracellular agonists, including adenosine, through purinergic receptors. Adenosine is a Food and Drug Administration-approved drug, but very little is known about the effect of adenosine on IC function. Therefore, we investigated the role of adenosine in the regulation of V-ATPase in ICs. Intravenous treatment of mice with adenosine or agonists of ADORA2A and ADORA2B purinergic P1 receptors induced V-ATPase apical membrane accumulation in medullary A-ICs but not in cortical A-ICs or other IC subtypes. Both receptors are located in A-IC apical membranes, and adenosine injection increased urine adenosine concentration and decreased urine pH. Cell fractionation showed that adenosine or an ADORA2A or ADORA2B agonist induced V-ATPase translocation from vesicles to the plasma membrane and increased protein kinase A (PKA)-dependent protein phosphorylation in purified medullary ICs that were isolated from mice. Either ADORA2A or ADORA2B antagonists or the PKA inhibitor mPKI blocked these effects. Finally, a fluorescence pH assay showed that adenosine activates V-ATPase in isolated medullary ICs. Our study shows that medullary A-ICs respond to luminal adenosine through ADORA2A and ADORA2B receptors in a cAMP/PKA pathway-dependent mechanism to induce V-ATPase-dependent H+ secretion.
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Affiliation(s)
- Maria A Battistone
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Anil V Nair
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Claire R Barton
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Rachel N Liberman
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Maria A Peralta
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Diane E Capen
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Dennis Brown
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Sylvie Breton
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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Gao C, Zhang L, Zhang Y, Wallace DP, Lopez-Soler RI, Higgins PJ, Zhang W. Insights into cellular and molecular basis for urinary tract infection in autosomal-dominant polycystic kidney disease. Am J Physiol Renal Physiol 2017; 313:F1077-F1083. [PMID: 28794066 DOI: 10.1152/ajprenal.00279.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 07/24/2017] [Accepted: 08/07/2017] [Indexed: 12/27/2022] Open
Abstract
Urinary tract infection (UTI) is a broad term referring to an infection of the kidneys, ureters, bladder, and/or urethra. Because of its prevalence, frequent recurrence, and rising resistance to antibiotics, UTI has become a challenge in clinical practice. Autosomal-dominant polycystic kidney disease (ADPKD) is the most common monogenic disorder of the kidney and is characterized by the growth of fluid-filled cysts in both kidneys. Progressive cystic enlargement, inflammation, and interstitial fibrosis result in nephron loss with subsequent decline in kidney function. ADPKD patients frequently develop UTI; however, the cellular and molecular mechanisms responsible for the high UTI incidence in ADPKD patients remain virtually unaddressed. Emerging evidence suggests that α-intercalated cells (α-ICs) of the collecting ducts function in the innate immune defense against UTI. α-ICs inhibit bacterial growth by acidifying urine and secreting neutrophil gelatinase-associated lipocalin (NGAL) that chelates siderophore-containing iron. It is necessary to determine, therefore, if ADPKD patients with recurrent UTI have a reduced number and/or impaired function of α-ICs. Identification of the underlying cellular and molecular mechanisms may lead to the development of novel strategies to reduce UTI in ADPKD.
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Affiliation(s)
- Chao Gao
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, New York
| | - Long Zhang
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, New York
| | - Ye Zhang
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, New York
| | - Darren P Wallace
- Departments of Internal Medicine and Physiology and The Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas; and
| | - Reynold I Lopez-Soler
- Department of Surgery, Division of Transplantation, Albany Medical College, Albany, New York
| | - Paul J Higgins
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, New York
| | - Wenzheng Zhang
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, New York;
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31
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Rojas M, Díaz P, León P, Gonzalez AA, González M, Barrientos V, Pestov NB, Alzamora R, Michea L. Mineralocorticoids modulate the expression of the β-3 subunit of the Na +, K +-ATPase in the renal collecting duct. Channels (Austin) 2017. [PMID: 28636485 DOI: 10.1080/19336950.2017.1344800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Renal sodium reabsorption depends on the activity of the Na+,K+-ATPase α/β heterodimer. Four α (α1-4) and 3 β (β1-3) subunit isoforms have been described. It is accepted that renal tubule cells express α1/β1 dimers. Aldosterone stimulates Na+,K+-ATPase activity and may modulate α1/β1 expression. However, some studies suggest the presence of β3 in the kidney. We hypothesized that the β3 isoform of the Na+,K+-ATPase is expressed in tubular cells of the distal nephron, and modulated by mineralocorticoids. We found that β3 is highly expressed in collecting duct of rodents, and that mineralocorticoids decreased the expression of β3. Thus, we describe a novel molecular mechanism of sodium pump modulation that may contribute to the effects of mineralocorticoids on sodium reabsorption.
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Affiliation(s)
- Macarena Rojas
- a Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile , Santiago , Chile
| | - Pablo Díaz
- a Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile , Santiago , Chile
| | - Pablo León
- a Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile , Santiago , Chile
| | - Alexis A Gonzalez
- b Instituto de Química, Pontificia Universidad Católica de Valparaíso , Valparaíso , Chile
| | - Magdalena González
- a Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile , Santiago , Chile
| | - Víctor Barrientos
- a Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile , Santiago , Chile
| | - Nikolay B Pestov
- c Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry , Moscow , Russia.,d Department of Physiology and Pharmacology and Center for Diabetes and Endocrine Research , University of Toledo College of Medicine , Toledo , OH , USA
| | - Rodrigo Alzamora
- a Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile , Santiago , Chile.,e Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD) , Santiago , Chile
| | - Luis Michea
- a Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile , Santiago , Chile.,f Millennium Institute on Immunology and Immunotherapy , Santiago , Chile
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Werth M, Schmidt-Ott KM, Leete T, Qiu A, Hinze C, Viltard M, Paragas N, Shawber CJ, Yu W, Lee P, Chen X, Sarkar A, Mu W, Rittenberg A, Lin CS, Kitajewski J, Al-Awqati Q, Barasch J. Transcription factor TFCP2L1 patterns cells in the mouse kidney collecting ducts. eLife 2017; 6. [PMID: 28577314 PMCID: PMC5484618 DOI: 10.7554/elife.24265] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 06/03/2017] [Indexed: 12/19/2022] Open
Abstract
Although most nephron segments contain one type of epithelial cell, the collecting ducts consists of at least two: intercalated (IC) and principal (PC) cells, which regulate acid-base and salt-water homeostasis, respectively. In adult kidneys, these cells are organized in rosettes suggesting functional interactions. Genetic studies in mouse revealed that transcription factor Tfcp2l1 coordinates IC and PC development. Tfcp2l1 induces the expression of IC specific genes, including specific H+-ATPase subunits and Jag1. Jag1 in turn, initiates Notch signaling in PCs but inhibits Notch signaling in ICs. Tfcp2l1 inactivation deletes ICs, whereas Jag1 inactivation results in the forfeiture of discrete IC and PC identities. Thus, Tfcp2l1 is a critical regulator of IC-PC patterning, acting cell-autonomously in ICs, and non-cell-autonomously in PCs. As a result, Tfcp2l1 regulates the diversification of cell types which is the central characteristic of 'salt and pepper' epithelia and distinguishes the collecting duct from all other nephron segments. DOI:http://dx.doi.org/10.7554/eLife.24265.001
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Affiliation(s)
- Max Werth
- Columbia University, New York, United States
| | - Kai M Schmidt-Ott
- Columbia University, New York, United States.,Max Delbruck Center for Molecular Medicine, Berlin, Germany.,Department of Nephrology and Intensive Care Medicine, Charité - Universitaetsmedizin Berlin, Berlin, Germany
| | | | - Andong Qiu
- Columbia University, New York, United States.,Tongji University, Shanghai, China
| | | | - Melanie Viltard
- Columbia University, New York, United States.,Institute for European Expertise in Physiology, Paris, France
| | - Neal Paragas
- Columbia University, New York, United States.,University of Washington, Seattle, United States
| | | | - Wenqiang Yu
- Columbia University, New York, United States.,Fudan University, Shanghai, China
| | - Peter Lee
- Columbia University, New York, United States
| | - Xia Chen
- Columbia University, New York, United States
| | - Abby Sarkar
- Columbia University, New York, United States
| | - Weiyi Mu
- Columbia University, New York, United States
| | | | | | - Jan Kitajewski
- Columbia University, New York, United States.,University of Illinois at Chicago, Chicago, United States
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Abstract
Pendrin is a Na(+)-independent Cl(-)/HCO3(-) exchanger found in the apical regions of type B and non-A, non-B intercalated cells within the aldosterone-sensitive region of the nephron, i.e., the distal convoluted tubule (DCT), the connecting tubule (CNT), and the cortical collecting duct (CCD). Type B intercalated cells mediate Cl(-) absorption and HCO3(-) secretion primarily through pendrin-mediated Cl(-)/HCO3(-) exchange. This exchanger is upregulated with angiotensin II administration and in models of metabolic alkalosis, such as following administration of aldosterone or NaHCO3. In the absence of pendrin-mediated HCO3(-) secretion, an enhanced alkalosis is observed following aldosterone or NaHCO3 administration. However, probably of more significance is the role of pendrin in the pressor response to aldosterone. Pendrin mediates Cl(-) absorption and modulates aldosterone-induced Na(+) absorption mediated by the epithelial Na channel (ENaC). Pendrin changes ENaC activity by changing both channel open probability (Po) and surface density (N), at least partly by altering luminal HCO3(-) and ATP concentration. Thus aldosterone and angiotensin II stimulate pendrin expression and function, which stimulates ENaC activity, thereby contributing to the pressor response of these hormones. However, pendrin may modulate blood pressure partly through its extrarenal effects. For example, pendrin is expressed in the adrenal medulla, where it modulates catecholamine release. The increase in catecholamine release observed with pendrin gene ablation likely contributes to the increment in vascular contractile force observed in the pendrin null mouse. This review summarizes the signaling mechanisms that regulate pendrin abundance and function as well as the contribution of pendrin to distal nephron function.
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Affiliation(s)
- Susan M Wall
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; and Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
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34
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Abstract
Pendrin is a Na(+)-independent Cl(-)/HCO3(-) exchanger that localizes to type B and non-A, non-B intercalated cells, which are expressed within the aldosterone-sensitive region of the nephron, i.e., the distal convoluted tubule, the connecting tubule, and the cortical collecting duct. Type B cells mediate Cl(-) absorption and HCO3(-) secretion primarily through pendrin-mediated Cl(-)/HCO3(-) exchange. At least in some treatment models, pendrin acts in tandem with the Na(+)-dependent Cl(-)/HCO3(-) exchanger (NDCBE) encoded by Slc4a8 to mediate NaCl absorption. The pendrin-mediated Cl(-)/HCO3(-) exchange process is greatly upregulated in models of metabolic alkalosis, such as following aldosterone administration or dietary NaHCO3 loading. It is also upregulated by angiotensin II. In the absence of pendrin [Slc26a4 (-/-) or pendrin null mice], aldosterone-stimulated NaCl absorption is reduced, which lowers the blood pressure response to aldosterone and enhances the alkalosis that follows the administration of this steroid hormone. Pendrin modulates aldosterone-induced Na(+) absorption by changing ENaC abundance and function through a kidney-specific mechanism that does not involve changes in the concentration of a circulating hormone. Instead, pendrin changes ENaC abundance and function at least in part by altering luminal HCO3(-) and ATP concentrations. Thus, aldosterone and angiotensin II also stimulate pendrin expression and function, which likely contributes to the pressor response of these hormones. This review summarizes the contribution of the Cl(-)/HCO3(-) exchanger pendrin in distal nephron function.
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Cowley AW, Yang C, Kumar V, Lazar J, Jacob H, Geurts AM, Liu P, Dayton A, Kurth T, Liang M. Pappa2 is linked to salt-sensitive hypertension in Dahl S rats. Physiol Genomics 2015; 48:62-72. [PMID: 26534937 DOI: 10.1152/physiolgenomics.00097.2015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 10/29/2015] [Indexed: 01/11/2023] Open
Abstract
A 1.37 Mbp region of chromosome 13 previously identified by exclusion mapping was consistently associated with a reduction of salt-induced hypertension in the Dahl salt-sensitive (SS) rat. This region contained five genes that were introgressed from the salt-insensitive Brown Norway (BN) rat. The goal of the present study was to further narrow that region to identify the gene(s) most likely to protect from salt-induced hypertension. The studies yielded a subcongenic SS rat strain containing a 0.71 Mbp insert from BN (26-P strain) in which salt-induced hypertension was reduced by 24 mmHg. The region contained two protein-coding genes (Astn1 and Pappa2) and a microRNA (miR-488). Pappa2 mRNA in the renal cortex of the protected 26-P was 6- to 10-fold greater than in SS fed a 0.4% NaCl diet but was reduced to levels observed in SS when fed 8.0% NaCl diet for 7 days. Compared with brain nuclei (NTS, RVLM, CVLM) and the adrenal gland, Pappa2 in the renal cortex was the only gene found to be differentially expressed between SS and 26-P and that responded to changes of salt diet. Immunohistochemistry studies found Pappa2 localized in the cytosol of the epithelial cells of the cortical thick ascending limbs. In more distal segments of the renal tubules, it was observed within tubular lumens and most notably bound to the apical membranes of the intercalated cells of collecting ducts. We conclude that we have identified a variant form of Pappa2 that can protect against salt-induced hypertension in the Dahl S rat.
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Affiliation(s)
- Allen W Cowley
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin;
| | - Chun Yang
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Vikash Kumar
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Jozef Lazar
- Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Howard Jacob
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Aron M Geurts
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin; and
| | - Pengyuan Liu
- Cancer Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Alex Dayton
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Theresa Kurth
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Mingyu Liang
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
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Labarca M, Nizar JM, Walczak EM, Dong W, Pao AC, Bhalla V. Harvest and primary culture of the murine aldosterone-sensitive distal nephron. Am J Physiol Renal Physiol 2015; 308:F1306-15. [PMID: 25810438 DOI: 10.1152/ajprenal.00668.2014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/19/2015] [Indexed: 11/22/2022] Open
Abstract
The aldosterone-sensitive distal nephron (ASDN) exhibits axial heterogeneity in structure and function from the distal convoluted tubule to the medullary collecting duct. Ion and water transport is primarily divided between the cortex and medulla of the ASDN, respectively. Transcellular transport in this segment is highly regulated in health and disease and is integrated across different cell types. We currently lack an inexpensive, high-yield, and tractable technique to harvest and culture cells for the study of gene expression and physiological properties of mouse cortical ASDN. To address this need, we harvested tubules bound to Dolichos biflorus agglutinin lectin-coated magnetic beads from the kidney cortex and characterized these cell preparations. We determined that these cells are enriched for markers of distal convoluted tubule, connecting tubule, and cortical collecting duct, including principal and intercalated cells. In primary culture, these cells develop polarized monolayers with high resistance (1,000-1,500 Ω * cm(2)) and maintain expression and activity of key channels. These cells demonstrate an amiloride-sensitive short-circuit current that can be enhanced with aldosterone and maintain measurable potassium and anion secretion. Our method can be easily adopted to study the biology of the ASDN and to investigate phenotypic differences between wild-type and transgenic mouse models.
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Affiliation(s)
- Mariana Labarca
- Division of Nephrology, Department of Medicine, Stanford University, Palo Alto, California; and
| | - Jonathan M Nizar
- Division of Nephrology, Department of Medicine, Stanford University, Palo Alto, California; and
| | - Elisabeth M Walczak
- Division of Nephrology, Department of Medicine, Stanford University, Palo Alto, California; and
| | - Wuxing Dong
- Division of Nephrology, Department of Medicine, Stanford University, Palo Alto, California; and
| | - Alan C Pao
- Division of Nephrology, Department of Medicine, Stanford University, Palo Alto, California; and Division of Nephrology, Department of Medicine, Veterans Affairs Palo Alto Healthcare System, Palo Alto, California
| | - Vivek Bhalla
- Division of Nephrology, Department of Medicine, Stanford University, Palo Alto, California; and
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van den Wildenberg MJ, Hoorn EJ, Mohebbi N, Wagner CA, Woittiez AJ, de Vries PAM, Laverman GD. Distal renal tubular acidosis with multiorgan autoimmunity: a case report. Am J Kidney Dis 2014; 65:607-10. [PMID: 25533600 DOI: 10.1053/j.ajkd.2014.09.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 09/11/2014] [Indexed: 11/11/2022]
Abstract
A 61-year-old woman with a history of pernicious anemia presented with progressive muscle weakness and dysarthria. Hypokalemic paralysis (serum potassium, 1.4 mEq/L) due to distal renal tubular acidosis (dRTA) was diagnosed. After excluding several possible causes, dRTA was considered autoimmune. However, the patient did not meet criteria for any of the autoimmune disorders classically associated with dRTA. She had very high antibody titers against parietal cells, intrinsic factor, and thyroid peroxidase (despite normal thyroid function). The patient consented to a kidney biopsy, and acid-base transporters, anion exchanger type 1 (AE1), and pendrin were undetectable by immunofluorescence. Indirect immunofluorescence detected diminished abundance of AE1- and pendrin-expressing intercalated cells in the kidney, as well as staining by the patient's serum of normal human intercalated cells and parietal cells expressing the adenosine triphosphatase hydrogen/potassium pump (H(+)/K(+)-ATPase) in normal human gastric mucosa. The dRTA likely is caused by circulating autoantibodies against intercalated cells, with possible cross-reactivity against structures containing gastric H(+)/K(+)-ATPase. This case demonstrates that in patients with dRTA without a classic autoimmune disorder, autoimmunity may still be the underlying cause. The mechanisms involved in autoantibody development and how dRTA can be caused by highly specific autoantibodies against intercalated cells have yet to be determined.
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Affiliation(s)
| | - Ewout J Hoorn
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Nilufar Mohebbi
- Division of Nephrology, University Hospital Zurich, Zürich, Switzerland; Institute of Physiology and Zürich Center for Human Intergrative Physiology, University of Zürich, Zürich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology and Zürich Center for Human Intergrative Physiology, University of Zürich, Zürich, Switzerland
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Hains DS, Chen X, Saxena V, Barr-Beare E, Flemming W, Easterling R, Becknell B, Schwartz GJ, Schwaderer AL. Carbonic anhydrase 2 deficiency leads to increased pyelonephritis susceptibility. Am J Physiol Renal Physiol 2014; 307:F869-80. [PMID: 25143453 DOI: 10.1152/ajprenal.00344.2014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Carbonic anhydrase 2 regulates acid-base homeostasis, and recent findings have indicated a correlation between cellular control of acid-base status and the innate defense of the kidney. Mice deficient in carbonic anhydrase 2 (Car2(-/-) mice) have metabolic acidosis, impaired urine acidification, and are deficient in normal intercalated cells. The objective of the present study was to evaluate the biological consequences of carbonic anhydrase 2 deficiency in a murine model of pyelonephritis. Infection susceptibility and transcription of bacterial response components in Car2(-/-) mice were compared with wild-type littermate controls. Car2(-/-) mice had increased kidney bacterial burdens along with decreased renal bacterial clearance after inoculation compared with wild-type mice. Standardization of the urine pH and serum HCO(3)(-) levels did not substantially alter kidney infection susceptibility between wild-type and Car2(-/-) mice; thus, factors other than acid-base status are responsible. Car2(-/-) mice had significantly increased neutrophil-gelatinase-associated lipocalin mRNA and protein and expression at baseline and a marked decreased ability to upregulate key bacterial response genes during pyelonephritis. Our findings provide in vivo evidence that supports a role for carbonic anhydrase 2 and intercalated cells in promoting renal bacterial clearance. Decreased carbonic anhydrase expression results in increased antimicrobial peptide production by cells other than renal intercalated cells, which is not sufficient to prevent infection after a bacterial challenge.
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Affiliation(s)
- David S Hains
- Division of Nephrology, Le Bonheur Children's Hospital, Memphis, Tennessee
| | - Xi Chen
- Division of Nephrology, Le Bonheur Children's Hospital, Memphis, Tennessee; Center for Clinical and Translational Medicine, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio
| | - Vijay Saxena
- Center for Clinical and Translational Medicine, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio
| | - Evan Barr-Beare
- Center for Clinical and Translational Medicine, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio
| | - Weisi Flemming
- Center for Clinical and Translational Medicine, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio
| | - Robert Easterling
- Center for Clinical and Translational Medicine, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio
| | - Brian Becknell
- Center for Clinical and Translational Medicine, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio; Division of Nephrology, Nationwide Children's Hospital, Columbus, Ohio; Department of Pediatrics, The Ohio State University, Columbus, Ohio
| | - George J Schwartz
- Department of Pediatrics, The University of Rochester, Rochester, New York
| | - Andrew L Schwaderer
- Center for Clinical and Translational Medicine, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio; Division of Nephrology, Nationwide Children's Hospital, Columbus, Ohio; Department of Pediatrics, The Ohio State University, Columbus, Ohio;
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Xu J, Barone S, Brooks MB, Soleimani M. Double knockout of carbonic anhydrase II (CAII) and Na(+)-Cl(-) cotransporter (NCC) causes salt wasting and volume depletion. Cell Physiol Biochem 2013; 32:173-83. [PMID: 24429824 PMCID: PMC10947769 DOI: 10.1159/000356637] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND AND AIMS The thiazide-sensitive Na(+)-Cl(-) cotransporter NCC and the Cl(-)/HCO3(-)exchanger pendrin are expressed on apical membranes of distal cortical nephron segments and mediate salt absorption, with pendrin working in tandem with the epithelial Na(+) channel (ENaC) and the Na(+)-dependent chloride/bicarbonate exchanger (NDCBE), whereas NCC is working by itself. A recent study showed that NCC and pendrin compensate for loss of each other under basal conditions, therefore masking the role that each plays in salt reabsorption. Carbonic anhydrase II (CAII, CA2 or CAR2) plays an important role in acid-base transport and salt reabsorption in the proximal convoluted tubule and acid-base transport in the collecting duct. Animals with CAII deletion show remodeling of intercalated cells along with the downregulation of pendrin. NCC KO mice on the other hand show significant upregulation of pendrin and ENaC. Neither model shows any significant salt wasting under baseline conditions. We hypothesized that the up-regulation of pendrin is essential for the prevention of salt wasting in NCC KO mice. METHODS AND RESULTS To test this hypothesis, we generated NCC/CAII double KO (dKO) mice by crossing mice with single deletion of NCC and CAII. The NCC/CAII dKO mice displayed significant downregulation of pendrin, along with polyuria and salt wasting. As a result, the dKO mice developed volume depletion, which was associated with the inability to concentrate urine. CONCLUSIONS We conclude that the upregulation of pendrin is essential for the prevention of salt and water wasting in NCC deficient animals and its downregulation or inactivation will result in salt wasting, impaired water conservation and volume depletion in the setting of NCC inactivation or inhibition.
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Affiliation(s)
- Jie Xu
- Research Services, Veterans Affairs Medical Center, University of Cincinnati
- Departments of Medicine, University of Cincinnati
| | - Sharon Barone
- Research Services, Veterans Affairs Medical Center, University of Cincinnati
- Departments of Medicine, University of Cincinnati
| | | | - Manoocher Soleimani
- Research Services, Veterans Affairs Medical Center, University of Cincinnati
- Departments of Medicine, University of Cincinnati
- Center on Genetics of Transport and Epithelial Biology, University of Cincinnati Cincinnati, OH, USA
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Abstract
In the distal nephron, the large-conductance Ca-activated K (BK) channel, comprised of a pore-forming-α (BK-α) and the BK-β4 subunit, promotes K excretion when mice are maintained on a high-K alkaline diet (HK-alk). We examined whether BK-β4 and the acid-base status regulate apical membrane expression of BK-α in the cortical (CCD) and medullary collecting ducts (MCD) using immunohistochemical analysis (IHC) and Western blot. With the use of IHC, BK-α of mice on acontrol diet localized mostly cytoplasmically in intercalated cells (IC) of the CCD and in the perinuclear region of both principle cells (PC) and IC of the MCD. HK-alk wild-type mice (WT), but not BK-β4 knockout mice (β4KO), exhibited increased apical BK-α in both the CCD and MCD. When given a high-K acidic diet (HK-Cl), BK-α expression increased but remained cytoplasmic in the CCD and perinuclear in the MCD of both WT and β4KO. Western blot confirmed that total BK-α expression was enhanced by either HK-alk or HK-Cl but only increased in the plasma membrane with HK-alk. Compared with controls, mice drinking NaHCO3 water exhibited more apical BK-α and total cellular BK-β4. Spironolactone given to mice on HK-alk significantly reduced K secretion and decreased total cellular BK-α but did not affect cellular BK-β4 and apical BK-α. Experiments with MDCK-C11 cells indicated that BK-β4 stabilizes surface BK-α by inhibiting degradation through a lysosomal pathway. These data suggest that aldosterone mediates a high-K-induced increase in BK-α and urinary alkalinization increases BK-β4 expression, which promotes the apical localization of BK-α.
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Affiliation(s)
- Donghai Wen
- Dept. of Cellular and Integrative Physiology, 985850 Nebraska Medical Center, Omaha, NE 68198-5850.
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41
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Abstract
Renal intercalated cells mediate the secretion or absorption of Cl(-) and OH(-)/H(+) equivalents in the connecting segment (CNT) and cortical collecting duct (CCD). In so doing, they regulate acid-base balance, vascular volume, and blood pressure. Cl(-) absorption is either electrogenic and amiloride-sensitive or electroneutral and thiazide-sensitive. However, which Cl(-) transporter(s) are targeted by these diuretics is debated. While epithelial Na(+) channel (ENaC) does not transport Cl(-), it modulates Cl(-) transport probably by generating a lumen-negative voltage, which drives Cl(-) flux across tight junctions. In addition, recent evidence indicates that ENaC inhibition increases electrogenic Cl(-) secretion via a type A intercalated cells. During ENaC blockade, Cl(-) is taken up across the basolateral membrane through the Na(+)-K(+)-2Cl(-) cotransporter (NKCC1) and then secreted across the apical membrane through a conductive pathway (a Cl(-) channel or an electrogenic exchanger). The mechanism of this apical Cl(-) secretion is unresolved. In contrast, thiazide diuretics inhibit electroneutral Cl(-) absorption mediated by a Na(+)-dependent Cl(-)/HCO3(-) exchanger. The relative contribution of the thiazide and the amiloride-sensitive components of Cl(-) absorption varies between studies and probably depends on the treatment model employed. Cl(-) absorption increases markedly with angiotensin and aldosterone administration, largely by upregulating the Na(+)-independent Cl(-)/HCO3(-) exchanger pendrin. In the absence of pendrin [Slc26a4((-/-)) or pendrin null mice], aldosterone-stimulated Cl(-) absorption is significantly reduced, which attenuates the pressor response to this steroid hormone. Pendrin also modulates aldosterone-induced changes in ENaC abundance and function through a kidney-specific mechanism that does not involve changes in the concentration of a circulating hormone. Instead, pendrin changes ENaC abundance and function, at least in part, by altering luminal HCO3(-). This review summarizes mechanisms of Cl(-) transport in CNT and CCD and how these transporters contribute to the regulation of extracellular volume and blood pressure.
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Affiliation(s)
- Susan M Wall
- Renal Division, WMB Rm. 338, 1639 Pierce Dr., NE, Atlanta, GA 30322.
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Geracitano R, Fischer D, Kasugai Y, Ferraguti F, Capogna M. Functional expression of the GABA(A) receptor α2 and α3 subunits at synapses between intercalated medial paracapsular neurons of mouse amygdala. Front Neural Circuits 2012; 6:32. [PMID: 22666188 PMCID: PMC3364593 DOI: 10.3389/fncir.2012.00032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 05/07/2012] [Indexed: 01/11/2023] Open
Abstract
In the amygdala, GABAergic neurons in the intercalated medial paracapsular cluster (Imp) have been suggested to play a key role in fear learning and extinction. These neurons project to the central (CE) amygdaloid nucleus and to other areas within and outside the amygdala. In addition, they give rise to local collaterals that innervate other neurons in the Imp. Several drugs, including benzodiazepines (BZ), are allosteric modulators of GABAA receptors. BZ has both anxiolytic and sedative actions, which are mediated through GABAA receptors containing α2/α3 and α1 subunits, respectively. To establish whether α1 or α2/α3 subunits are expressed at Imp cell synapses, we used paired recordings of anatomically identified Imp neurons and high resolution immunocytochemistry in the mouse. We observed that a selective α3 subunit agonist, TP003 (100 nM), significantly increased the decay time constant of the unitary IPSCs. A similar effect was also induced by zolpidem (10 μM) or by diazepam (1 μM). In contrast, lower doses of zolpidem (0.1–1 μM) did not significantly alter the kinetics of the unitary IPSCs. Accordingly, immunocytochemical experiments established that the α2 and α3, but not the α1 subunits of the GABAA receptors, were present at Imp cell synapses of the mouse amygdala. These results define, for the first time, some of the functional GABAA receptor subunits expressed at synapses of Imp cells. The data also provide an additional rationale to prompt the search of GABAA receptor α3 selective ligands as improved anxiolytic drugs.
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Affiliation(s)
- Raffaella Geracitano
- Medical Research Council, Anatomical Neuropharmacology Unit, Department of Pharmacology, University of Oxford Oxford, UK
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Vijayakumar S, Takito J, Hikita C, Al-Awqati Q. Hensin remodels the apical cytoskeleton and induces columnarization of intercalated epithelial cells: processes that resemble terminal differentiation. J Biophys Biochem Cytol 1999; 144:1057-67. [PMID: 10085301 PMCID: PMC2148197 DOI: 10.1083/jcb.144.5.1057] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Intercalated epithelial cells exist in a spectrum of phenotypes; at one extreme, beta cells secrete HCO3 by an apical Cl/HCO3 exchanger and a basolateral H+ ATPase. When an immortalized beta cell line is seeded at high density it deposits in its extracellular matrix (ECM) a new protein, hensin, which can reverse the polarity of several proteins including the Cl/HCO3 exchanger (an alternately spliced form of band 3) and the proton translocating ATPase. When seeded at low density and allowed to form monolayers these polarized epithelial cells maintain the original distribution of these two proteins. Although these cells synthesize and secrete hensin, it is not retained in the ECM, but rather, hensin is present in a large number of intracellular vesicles. The apical cytoplasm of low density cells is devoid of actin, villin, and cytokeratin19. Scanning electron microscopy shows that these cells have sparse microvilli, whereas high density cells have exuberant apical surface infolding and microvilli. The apical cytoplasm of high density cells contains high levels of actin, cytokeratin19, and villin. The cell shape of these two phenotypes is different with high density cells being tall with a small cross-sectional area, whereas low density cells are low and flat. This columnarization and the remodeling of the apical cytoplasm is hensin-dependent; it can be induced by seeding low density cells on filters conditioned by high density cells and prevented by an antibody to hensin. The changes in cell shape and apical cytoskeleton are reminiscent of the processes that occur in terminal differentiation of the intestine and other epithelia. Hensin is highly expressed in the intestine and prostate (two organs where there is a continuous process of differentiation). The expression of hensin in the less differentiated crypt cells of the intestine and the basal cells of the prostate is similar to that of low density cells; i.e., abundant intracellular vesicles but no localization in the ECM. On the other hand, as in high density cells hensin is located exclusively in the ECM of the terminally differentiated absorptive villus cells and the prostatic luminal cell. These studies suggest that hensin is a critical new molecule in the terminal differentiation of intercalated cell and perhaps other epithelial cells.
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Affiliation(s)
- S Vijayakumar
- Department of Medicine and Department of Physiology, College of Physicians and Surgeons of Columbia University, New York 10032, USA
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