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Abstract
Type 1 and 2 diabetes mellitus are major medical epidemics affecting millions of patients worldwide. Diabetes mellitus is the leading cause of diabetic kidney disease (DKD), which is the most common cause of end-stage renal disease (ESRD). DKD is associated with significant changes in renal hemodynamics and electrolyte transport. Alterations in renal ion transport triggered by pathophysiological conditions in diabetes can exacerbate hypertension, accelerate renal injury, and are integral to the development of DKD. Renal ion transporters and electrolyte homeostasis play a fundamental role in functional changes and injury to the kidney during DKD. With the large number of ion transporters involved in DKD, understanding the roles of individual transporters as well as the complex cascades through which they interact is essential in the development of effective treatments for patients suffering from this disease. This chapter aims to gather current knowledge of the major renal ion transporters with altered expression and activity under diabetic conditions, and provide a comprehensive overview of their interactions and collective functions in DKD.
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Affiliation(s)
- Denisha Spires
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Anna D Manis
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Alexander Staruschenko
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States; Clement J. Zablocki VA Medical Center, Milwaukee, WI, United States.
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152
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Marunaka Y, Niisato N, Miyazaki H, Nakajima KI, Taruno A, Sun H, Marunaka R, Okui M, Yamamoto T, Kanamura N, Kogiso H, Ikeuchi Y, Kashio M, Hosogi S, Nakahari T. Quercetin is a Useful Medicinal Compound Showing Various Actions Including Control of Blood Pressure, Neurite Elongation and Epithelial Ion Transport. Curr Med Chem 2019; 25:4876-4887. [PMID: 27655075 DOI: 10.2174/0929867323666160919095043] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [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: 06/23/2016] [Revised: 07/21/2016] [Accepted: 07/21/2016] [Indexed: 11/22/2022]
Abstract
Quercetin has multiple potential to control various cell function keeping our body condition healthy. In this review article, we describe the molecular mechanism on how quercetin exerts its action on blood pressure, neurite elongation and epithelial ion transport based from a viewpoint of cytosolic Cl- environments, which is recently recognized as an important signaling factor in various types of cells. Recent studies show various roles of cytosolic Cl- in regulation of blood pressure and neurite elongation, and prevention from bacterial and viral infection. We have found the stimulatory action of quercetin on Cl- transporter, Na+-K+-2Cl- cotransporter 1 (NKCC1; an isoform of NKCC), which has been recognized as one of the most interesting, fundamental actions of quercetin. In this review article, based on this stimulatory action of quercetin on NKCC1, we introduce the molecular mechanism of quercetin on: 1) blood pressure, 2) neurite elongation, and 3) epithelial Cl- secretion including tight junction forming in epithelial tissues. 1) Quercetin induces elevation of the cytosolic Cl- concentration via activation of NKCC1, leading to anti-hypertensive action by diminishing expression of epithelial Na+ channel (ENaC), a key ion channel involved in renal Na+ reabsorption, while quercetin has no effects on the blood pressure with normal salt intake. 2) Quercetin also has stimulatory effects on neurite elongation by elevating the cytosolic Cl- concentration via activation of NKCC1 due to tubulin polymerization facilitated through Cl--induced inhibition of GTPase. 3) Further, in lung airway epithelia quercetin stimulates Cl- secretion by increasing the driving force for Cl- secretion via elevation of the cytosolic Cl- concentration: this leads to water secretion, participating in prevention of our body from bacterial and viral infection. In addition to transcellular ion transport, quercetin regulates tight junction function via enhancement of tight junction integrity by modulating expression and assembling tight junction-forming proteins. Based on these observations, it is concluded that quercetin is a useful medicinal compound keeping our body to be in healthy condition.
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Affiliation(s)
- Yoshinori Marunaka
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.,Department of Bio-Ionomics, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.,Japan Institute for Food Education and Health, St. Agnes' University, Kyoto 602-8013, Japan
| | - Naomi Niisato
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.,Japan Institute for Food Education and Health, St. Agnes' University, Kyoto 602-8013, Japan.,Department of Health and Sports Sciences, Faculty of Health and Medical Sciences, Kyoto Gakuen University, Kameoka 621-8555, Japan
| | - Hiroaki Miyazaki
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.,Japan Institute for Food Education and Health, St. Agnes' University, Kyoto 602-8013, Japan
| | - Ken-Ichi Nakajima
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Akiyuki Taruno
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Hongxin Sun
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Rie Marunaka
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.,Department of Dental Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Motoki Okui
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.,Department of Dental Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Toshiro Yamamoto
- Department of Dental Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Narisato Kanamura
- Department of Dental Medicine, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Haruka Kogiso
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Yukiko Ikeuchi
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Makiko Kashio
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Shigekuni Hosogi
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.,Department of Bio-Ionomics, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.,Japan Institute for Food Education and Health, St. Agnes' University, Kyoto 602-8013, Japan
| | - Takashi Nakahari
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.,Department of Bio-Ionomics, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.,Japan Institute for Food Education and Health, St. Agnes' University, Kyoto 602-8013, Japan
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153
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Hou Y, Cui Y, Zhou Z, Liu H, Zhang H, Ding Y, Nie H, Ji HL. Upregulation of the WNK4 Signaling Pathway Inhibits Epithelial Sodium Channels of Mouse Tracheal Epithelial Cells After Influenza A Infection. Front Pharmacol 2019; 10:12. [PMID: 30723408 PMCID: PMC6349759 DOI: 10.3389/fphar.2019.00012] [Citation(s) in RCA: 9] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 01/07/2019] [Indexed: 12/28/2022] Open
Abstract
Influenza virus has a significant impact on the respiratory system. The mechanism of how influenza virus impairs the fluid transport in airway is not fully understood. We examined its effects on epithelial sodium channels (ENaC), which are very important for water and salt transport in the respiratory system. We focused on the impacts of influenza virus on ENaC activity in mouse tracheal epithelial cells (MTECs) and applied Ussing chamber apparatus for recording the short-circuit currents in primary cultured MTECs. Expressions of α and γ-ENaC were measured at the protein and mRNA levels by western blot and quantitative real-time polymerase chain reaction, respectively. Roles of the with-no-lysine-kinase-4 (WNK4) pathway were considered in participating influenza virus-involved ENaC regulation by using siRNA to knockdown WNK4 and the physical properties of airway surface liquid (ASL) were detected by confocal microscopy. Our results showed that influenza virus reduced ENaC activity, and the expressions of α and γ-ENaC were decreased at the protein and mRNA levels, respectively. WNK4 expression increased time-dependently at the protein level after influenza virus infection, while knockdown of WNK4 rescued the impact of influenza virus on ENaC and ASL height increased obviously after MTECs were treated with influenza virus. Taken together, these results suggest that influenza virus causes the changes of biophysical profile in the airway by altering the ENaC activity at least partly via facilitating the expression of WNK4.
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Affiliation(s)
- Yapeng Hou
- Department of Stem Cells and Regenerative Medicine, Key Laboratory of Cell Biology, National Health Commission of China, Key Laboratory of Medical Cell Biology, Ministry of Education of China, China Medical University, Shenyang, China
| | - Yong Cui
- Department of Anesthesiology, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Zhiyu Zhou
- Department of Stem Cells and Regenerative Medicine, Key Laboratory of Cell Biology, National Health Commission of China, Key Laboratory of Medical Cell Biology, Ministry of Education of China, China Medical University, Shenyang, China
| | - Hongfei Liu
- Department of Stem Cells and Regenerative Medicine, Key Laboratory of Cell Biology, National Health Commission of China, Key Laboratory of Medical Cell Biology, Ministry of Education of China, China Medical University, Shenyang, China
| | - Honglei Zhang
- Department of Stem Cells and Regenerative Medicine, Key Laboratory of Cell Biology, National Health Commission of China, Key Laboratory of Medical Cell Biology, Ministry of Education of China, China Medical University, Shenyang, China
| | - Yan Ding
- Department of Stem Cells and Regenerative Medicine, Key Laboratory of Cell Biology, National Health Commission of China, Key Laboratory of Medical Cell Biology, Ministry of Education of China, China Medical University, Shenyang, China
| | - Hongguang Nie
- Department of Stem Cells and Regenerative Medicine, Key Laboratory of Cell Biology, National Health Commission of China, Key Laboratory of Medical Cell Biology, Ministry of Education of China, China Medical University, Shenyang, China
| | - Hong-Long Ji
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, TX, United States.,Texas Lung Injury Institute, The University of Texas Health Northeast, Tyler, TX, United States
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154
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Abstract
PURPOSE OF REVIEW In this review, we summarized the current knowledge of connecting tubule-glomerular feedback (CTGF), a novel mechanism of renal microcirculation regulation that integrates sodium handling in the connecting tubule (CNT) with kidney hemodynamics. RECENT FINDINGS Connecting tubule-glomerular feedback is a crosstalk communication between the CNT and the afferent arteriole (Af-Art), initiated by sodium chloride through the epithelial sodium channel (ENaC). High sodium in the CNT induces Af-Art vasodilation, increasing glomerular pressure and the glomerular filtration rate and favoring sodium excretion. CTGF antagonized and reset tubuloglomerular feedback and thus increased sodium excretion. CTGF is absent in spontaneous hypertensive rats and is overactivated in Dahl salt-sensitive rats. CTGF is also modulated by angiotensin II and aldosterone. CTGF is a feedback mechanism that integrates sodium handling in the CNT with glomerular hemodynamics. Lack of CTGF could promote hypertension, and CTGF overactivation may favor glomerular damage and proteinuria. More studies are needed to explore the alterations in renal microcirculation and the role of these alterations in the genesis of hypertension and glomerular damage in animals and humans. KEY POINTS • CTGF is a vasodilator mechanism that regulates afferent arteriole resistance. • CTGF is absent in spontaneous hypertensive rats and overactivated in Dahl salt-sensitive rats. • CTGF in excess may promote glomerular damage and proteinuria, while the absence may participate in sodium retention and hypertension.
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Affiliation(s)
- Cesar A Romero
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 2799 West Grand Boulevard, Detroit, MI, 48202-2689, USA.
| | - Oscar A Carretero
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 2799 West Grand Boulevard, Detroit, MI, 48202-2689, USA
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155
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Mies F, Virreira M, Goolaerts A, Djerbib S, Beauwens R, Shlyonsky V, Boom A. DUOX1-mediated hydrogen peroxide release regulates sodium transport in H441 bronchiolar epithelial cells. Acta Physiol (Oxf) 2019; 225:e13166. [PMID: 30052308 DOI: 10.1111/apha.13166] [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: 03/23/2018] [Revised: 07/23/2018] [Accepted: 07/24/2018] [Indexed: 11/26/2022]
Abstract
AIM Dexamethasone has been shown to induce the formation of epithelial domes by bronchiolar H441 cells. It stimulates the expression of both amiloride inhibitable epithelial sodium channels (ENaC) and dual oxidase-1 (DUOX1). We therefore ask the question whether DUOX1 expression and production of submillimolar amounts of H2 O2 is instrumental for the sodium channel upregulation observed in H441 cells. METHODS In vitro cell culture, nystatin-perforated whole-cell patch-clamp technique, immunocytochemistry and RT-PCR methods have been used. RESULTS Cells forming epithelial domes induced by dexamethasone (0.1 μmol L-1 , 24 hours) and by 5-aza-2'-deoxytidine (1 μmol L-1 , 48 hours) expressed more DUOX1 protein compared with other cells in the monolayer. Dome formation could be inhibited by exogenous catalase in a concentration-dependent manner and by the NADPH oxidase inhibitor diphenyliodonium, which suggested the involvement of H2 O2 . While single application of 0.2 mmol L-1 H2 O2 induced transient dome formation, lower doses were ineffective and higher doses disrupted the cell monolayer. Hydrogen peroxide (0.1 mmol L-1 ) activated acutely amiloride-sensitive whole-cell currents from 3.91 ± 0.79 pA pF-1 to 4.76 ± 0.98 pA pF-1 in dome-forming cells and had no effect in cells outside of domes. ENaC but not DUOX1 transcription was potentiated by catalase in the presence of dexamethasone, which suggested negative feedback of H2 O2 on ENaC gene expression. CONCLUSION Our observations suggest that tonic production of H2 O2 by DUOX1 participates in maintaining the level of vectorial sodium transport by lung epithelial cells. Moreover, the system appears to be well tuned as it would allow H2 O2 -dependent innate immunity without inducing airway/alveolar sodium and fluid hyperabsorption.
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Affiliation(s)
- Frédérique Mies
- Laboratory of Physiology and Pharmacology; Université libre de Bruxelles; Brussels Belgium
| | - Myrna Virreira
- Laboratory of Cell and Molecular Physiology; Université libre de Bruxelles; Brussels Belgium
| | - Arnaud Goolaerts
- Laboratory of Physiology and Pharmacology; Université libre de Bruxelles; Brussels Belgium
| | - Sami Djerbib
- Laboratory of Cell and Molecular Physiology; Université libre de Bruxelles; Brussels Belgium
| | - Renaud Beauwens
- Laboratory of Cell and Molecular Physiology; Université libre de Bruxelles; Brussels Belgium
| | - Vadim Shlyonsky
- Laboratory of Physiology and Pharmacology; Université libre de Bruxelles; Brussels Belgium
| | - Alain Boom
- Laboratory of Cell and Molecular Physiology; Université libre de Bruxelles; Brussels Belgium
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156
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Abstract
Since its discovery, aldosterone and ion modulation have been entwined. While scientific investigations throughout the decades have emphasized aldosterone's connection to Na+, K+, and H+ homeostasis, more recent research has demonstrated a relationship between aldosterone and Mg2+, Ca2+, and Cl- homeostasis. The mechanisms connecting aldosterone to ion regulation frequently involve ion channels; the membrane localized proteins containing at least one aqueous pore for ion conduction. In order to precisely control intracellular or intraorganelle ion concentrations, ion channels have evolved highly specific regions within the conduction pore that select ions by charge, size, and/or dehydration energy requirement, meaning aldosterone must be able to modulate multiple ion channels to regulate the many ions described above. The list of ion channels presently connected to aldosterone includes ENaC (Na+), ROMK/BK (K+), TRPV4/5/6 (Ca2+), TRPM7/6 (Mg2+), and ClC-K/CFTR (Cl-), among others. This list is only expected to grow over time, as the promiscuity of aldosterone becomes more understood.
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Affiliation(s)
| | - Rhian M Touyz
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Alvin Shrier
- Department of Physiology, McGill University, Montreal, QC, Canada.
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157
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Lenzig P, Wirtz M, Wiemuth D. Comparative electrophysiological analysis of the bile acid-sensitive ion channel (BASIC) from different species suggests similar physiological functions. Pflugers Arch 2018; 471:329-336. [PMID: 30353368 DOI: 10.1007/s00424-018-2223-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [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: 08/27/2018] [Revised: 10/11/2018] [Accepted: 10/12/2018] [Indexed: 12/29/2022]
Abstract
Despite the identification of cholangiocytes in the liver and unipolar brush cells in the cerebellum as sites of expression, the physiological function of the bile acid-sensitive ion channel (BASIC) remains unknown. Rat BASIC (rBASIC) and mouse BASIC (mBASIC) share 97% of their amino acid sequence but show strikingly different biophysical properties. rBASIC is inactive at rest while mBASIC is constitutively active, when expressed in Xenopus oocytes. This conundrum rendered the identification of the physiological function even more difficult. In this study, we investigated the electrophysiological and pharmacological properties of BASIC from rat, mouse, and human in Hek293 cells using the patch clamp technique. Surprisingly, in Hek293 cells, rBASIC and mBASIC showed almost completely identical properties. Both are blocked by extracellular Ca2+ and thus are inactive at rest; both are selective for Na+, show similar affinities for extracellular Ca2+, were inhibited by diminazene, and activated by various bile acids. This is in contrast to previous results derived from Xenopus oocytes as expression system and suggests that the cell type is important for shaping the biophysical properties of BASIC. Furthermore, we compared hBASIC with rBASIC and mBASIC and observed similar properties between these channels with one exception: the bile acid sensitivity profile of hBASIC is different from rBASIC and mBASIC; hBASIC is more sensitive to bile acids which are abundant in human bile but not in rodent bile. Taken together, these results suggest similar physiological roles for BASIC in different species.
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Affiliation(s)
- Pia Lenzig
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Monika Wirtz
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Dominik Wiemuth
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany.
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158
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Marunaka R, Taruno A, Yamamoto T, Kanamura N, Marunaka Y. Action of Protein Tyrosine Kinase Inhibitors on the Hypotonicity-Stimulated Trafficking Kinetics of Epithelial Na+ Channels ( ENaC) in Renal Epithelial Cells: Analysis Using a Mathematical Model. Cell Physiol Biochem 2018; 50:363-377. [PMID: 30308504 DOI: 10.1159/000494012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [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: 04/02/2018] [Accepted: 09/25/2018] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Epithelial Na+ channels (ENaCs) play crucial roles in control of blood pressure by determining the total amount of renal Na+ reabsorption, which is regulated by various factors such as aldosterone, vasopressin, insulin and osmolality. The intracellular trafficking process of ENaCs regulates the amount of the ENaC-mediated Na+ reabsorption in the collecting duct of the kidney mainly by determining the number of ENaC expressed at the apical membrane of epithelial cells. Although we previously reported protein tyrosine kinases (PTKs) contributed to the ENaC-mediated epithelial Na+ reabsorption, we have no information on the role of PTKs in the intracellular ENaC trafficking. METHODS Using the mathematical model recently established in our laboratory, we studied the effect of PTKs inhibitors (PTKIs), AG1296 (10 µM: an inhibitor of the PDGF receptor (PDGFR)) and AG1478 (10 µM: an inhibitor of the EGF receptor (EGFR)) on the rates of the intracellular ENaC trafficking in renal epithelial A6 cells endogenously expressing ENaCs. RESULTS We found that application of PTKIs significantly reduced the insertion rate of ENaC to the apical membrane by 56%, the recycling rate of ENaC by 83%, the cumulative time of an individual ENaC staying in the apical membrane by 27%, the whole life-time after the first insertion of ENaC by 47%, and the cumulative Na+ absorption by 61%, while the degradation rate was increased to 3.8-fold by application of PTKIs. These observations indicate that PTKs contribute to the processes of insertion, recycling and degradation of ENaC in the intracellular trafficking process under a hypotonic condition. CONCLUSION The present study indicates that application of EGFR and PDGFR-inhibitable PTKIs reduced the insertion rate (kI), and the recycling rate (kR) of ENaCs, but increased degradation rate (kD) in renal A6 epithelial cells under a hypotonic condition. These observations indicate that hypotonicity increases the surface expression of ENaCs by increasing the insertion rate (kI) and the recycling rate (kR) of ENaCs associated with a decrease in the degradation rate but without any significant effects on the endocytotic rate (kE) in EGFR and PDGFR-related PTKs-mediated pathways.
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Affiliation(s)
- Rie Marunaka
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan.,Department of Dental Medicine, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan
| | - Akiyuki Taruno
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan
| | - Toshiro Yamamoto
- Department of Dental Medicine, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan
| | - Narisato Kanamura
- Department of Dental Medicine, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan
| | - Yoshinori Marunaka
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan.,Japan Institute for Food Education and Health, St. Agnes' University, Kyoto, Japan.,Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto, Japan.,Research Center for Drug Discovery and Pharmaceutical Development Science, Research Organization of Science and Technology, Ritsumeikan University, Kusatsu, Japan
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159
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Abstract
Mucociliary clearance is critically important in protecting the airways from infection and from the harmful effects of smoke and various inspired substances known to induce oxidative stress and persistent inflammation. An essential feature of the clearance mechanism involves regulation of the periciliary liquid layer on the surface of the airway epithelium, which is necessary for normal ciliary beating and maintenance of mucus hydration. The underlying ion transport processes associated with airway surface hydration include epithelial Na+ channel-dependent Na+ absorption occurring in parallel with CFTR and Ca2+-activated Cl- channel-dependent anion secretion, which are coordinately regulated to control the depth of the periciliary liquid layer. Oxidative stress is known to cause both acute and chronic effects on airway ion transport function, and an increasing number of studies in the past few years have identified an important role for autophagy as part of the physiological response to the damaging effects of oxidation. In this review, recent studies addressing the influence of oxidative stress and autophagy on airway ion transport pathways, along with results showing the potential of autophagy modulators in restoring the function of ion channels involved in transepithelial electrolyte transport necessary for effective mucociliary clearance, are presented.
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Affiliation(s)
- Scott M O'Grady
- Departments of Animal Science, Integrative Biology and Physiology, University of Minnesota , St. Paul, Minnesota
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160
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Khadijah Ramli NS, Giribabu N, Salleh N. Testosterone enhances expression and functional activity of epithelial sodium channel ( ENaC), cystic fibrosis transmembrane regulator (CFTR) and sodium hydrogen exchanger (NHE) in vas deferens of sex-steroid deficient male rats. Steroids 2018; 138:117-133. [PMID: 30003911 DOI: 10.1016/j.steroids.2018.06.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 06/10/2018] [Accepted: 06/11/2018] [Indexed: 12/19/2022]
Abstract
UNLABELLED Effects of testosterone on expression and functional activity of ENaC, CFTR and NHE in vas deferens were investigated. METHODS Orchidectomized, adult male rats were given 125 and 250 μg/kg/day testosterone subcutaneously, with or without flutamide and finasteride for seven consecutive days. At the end of the treatment, rats were anesthetized and vas deferens were perfused. Changes in vas deferens fluid secretion rate, pH, HCO3-, Cl- and Na+ concentrations were recorded in the presence of amiloride and Cftr inh-172. Rats were then sacrificed and vas deferens were harvested and subjected for molecular biological analysis. RESULTS Testosterone treatment caused the fluid pH and HCO3- concentrations to decrease but secretion rate, Cl- and Na+ concentrations to increase, where upon amiloride administration, the pH and HCO3- concentration increased but Cl- and Na+ concentrations further increased. In testosterone-treated rats, administration of Cftr inh-172 caused all fluid parameters to decrease. In testosterone-treated rats co-administered with flutamide or finasteride, pH and HCO3- concentration increased but fluid secretion rate, Cl- and Na+ concentrations decreased and these parameters were not affected by amiloride or Cftr inh-172 administration. Under testosterone influence, CFTR and γ-ENaC were highly expressed at the apical membrane while NHE-1 and 4 were highly expressed at the basolateral membrane of vas deferens epithelium. Meanwhile, NHE-2 and 3 were highly expressed at the apical membrane. CONCLUSIONS Differential expression of ENaC, CFTR and NHE in vas deferens under testosterone influence indicated the important role of these transporters in creating optimal fluid microenvironment that is essential for preserving male fertility.
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Affiliation(s)
| | - Nelli Giribabu
- Department of Physiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Naguib Salleh
- Department of Physiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
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161
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Craigie E, Menzies RI, Larsen CK, Jacquillet G, Carrel M, Wildman SS, Loffing J, Leipziger J, Shirley DG, Bailey MA, Unwin RJ. The renal and blood pressure response to low sodium diet in P2X4 receptor knockout mice. Physiol Rep 2018; 6:e13899. [PMID: 30350402 PMCID: PMC6198136 DOI: 10.14814/phy2.13899] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [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] [Received: 04/24/2018] [Revised: 09/25/2018] [Accepted: 09/27/2018] [Indexed: 01/02/2023] Open
Abstract
In the kidney, purinergic (P2) receptor-mediated ATP signaling has been shown to be an important local regulator of epithelial sodium transport. Appropriate sodium regulation is crucial for blood pressure (BP) control and disturbances in sodium balance can lead to hypo- or hypertension. Links have already been established between P2 receptor signaling and the development of hypertension, attributed mainly to vascular and/or inflammatory effects. A transgenic mouse model with deletion of the P2X4 receptor (P2X4-/- ) is known to have hypertension, which is thought to reflect endothelial dysfunction and impaired nitric oxide (NO) release. However, renal function in this model has not been characterized; moreover, studies in vitro have shown that the P2X4 receptor can regulate renal epithelial Na+ channel (ENaC) activity. Therefore, in the present study we investigated renal function and sodium handling in P2X4-/- mice, focusing on ENaC-mediated Na+ reabsorption. We confirmed an elevated BP in P2X4-/- mice compared with wild-type mice, but found that ENaC-mediated Na+ reabsorption is no different from wild-type and does not contribute to the raised BP observed in the knockout. However, when P2X4-/- mice were placed on a low sodium diet, BP normalized. Plasma aldosterone concentration tended to increase according to sodium restriction status in both genotypes; in contrast to wild-types, P2X4-/- mice did not show an increase in functional ENaC activity. Thus, although the increased BP in P2X4-/- mice has been attributed to endothelial dysfunction and impaired NO release, there is also a sodium-sensitive component.
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Affiliation(s)
- Eilidh Craigie
- Centre for NephrologyUniversity College London Medical SchoolLondonUnited Kingdom
- Institue for AnatomyUniversity of ZürichZürichSwitzerland
| | - Robert I. Menzies
- British Heart Foundation Centre for Cardiovascular ScienceUniversity of EdinburghEdinburghUnited Kingdom
| | - Casper K. Larsen
- Department of Biomedicine, PhysiologyAarhus UniversityAarhus CDenmark
| | - Grégory Jacquillet
- Centre for NephrologyUniversity College London Medical SchoolLondonUnited Kingdom
| | - Monique Carrel
- Institue for AnatomyUniversity of ZürichZürichSwitzerland
| | - Scott S. Wildman
- Urinary System Physiology UnitMedway School of PharmacyUniversity of KentKentUnited Kingdom
| | | | - Jens Leipziger
- Department of Biomedicine, PhysiologyAarhus UniversityAarhus CDenmark
| | - David G. Shirley
- Centre for NephrologyUniversity College London Medical SchoolLondonUnited Kingdom
| | - Matthew A. Bailey
- British Heart Foundation Centre for Cardiovascular ScienceUniversity of EdinburghEdinburghUnited Kingdom
| | - Robert J. Unwin
- Centre for NephrologyUniversity College London Medical SchoolLondonUnited Kingdom
- CVRM iMEDAstraZeneca GothenburgGothenburgSweden
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Ramkumar N, Stuart D, Mironova E, Abraham N, Gao Y, Wang S, Lakshmipathi J, Stockand JD, Kohan DE. Collecting duct principal, but not intercalated, cell prorenin receptor regulates renal sodium and water excretion. Am J Physiol Renal Physiol 2018; 315:F607-F617. [PMID: 29790390 PMCID: PMC6172572 DOI: 10.1152/ajprenal.00122.2018] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [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: 03/15/2018] [Revised: 05/09/2018] [Accepted: 05/14/2018] [Indexed: 12/21/2022] Open
Abstract
The collecting duct is the predominant nephron site of prorenin and prorenin receptor (PRR) expression. We previously demonstrated that the collecting duct PRR regulates epithelial Na+ channel (ENaC) activity and water transport; however, which cell type is involved remains unclear. Herein, we examined the effects of principal cell (PC) or intercalated cell (IC) PRR deletion on renal Na+ and water handling. PC or IC PRR knockout (KO) mice were obtained by crossing floxed PRR mice with mice harboring Cre recombinase under the control of the AQP2 or B1 subunit of the H+ ATPase promoters, respectively. PC KO mice had reduced renal medullary ENaC-α abundance and increased urinary Na+ losses on a low-Na+ diet compared with controls. Conversely, IC KO mice had no apparent differences in Na+ balance or ENaC abundance compared with controls. Acute treatment with prorenin increased ENaC channel number and open probability in acutely isolated cortical collecting ducts from control and IC PRR KO, but not PC PRR KO, mice. Furthermore, compared with controls, PC KO, but not IC KO mice, had increased urine volume, reduced urine osmolality, and reduced abundance of renal medullary AQP2. Taken together, these findings indicate that PC, but not IC, PRR modulates ENaC activity, urinary Na+ excretion, and water transport.
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Affiliation(s)
- Nirupama Ramkumar
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center , Salt Lake City, Utah
| | - Deborah Stuart
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center , Salt Lake City, Utah
| | - Elena Mironova
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center , San Antonio, Texas
| | - Nikita Abraham
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center , Salt Lake City, Utah
| | - Yang Gao
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center , Salt Lake City, Utah
| | - Shuping Wang
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center , Salt Lake City, Utah
| | - Jayalakshmi Lakshmipathi
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center , Salt Lake City, Utah
| | - James D Stockand
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center , San Antonio, Texas
| | - Donald E Kohan
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center , Salt Lake City, Utah
- Department of Veterans Affairs Medical Center , Salt Lake City, Utah
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163
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Kandel C, Schmidt P, Perniss A, Keshavarz M, Scholz P, Osterloh S, Althaus M, Kummer W, Deckmann K. ENaC in Cholinergic Brush Cells. Front Cell Dev Biol 2018; 6:89. [PMID: 30159312 PMCID: PMC6103785 DOI: 10.3389/fcell.2018.00089] [Citation(s) in RCA: 6] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 07/25/2018] [Indexed: 12/17/2022] Open
Abstract
Cholinergic polymodal chemosensory cells in the mammalian urethra (urethral brush cells = UBC) functionally express the canonical bitter and umami taste transduction signaling cascade. Here, we aimed to determine whether UBC are functionally equipped for the perception of salt through ENaC (epithelial sodium channel). Cholinergic UBC were isolated from ChAT-eGFP reporter mice (ChAT = choline acetyltransferase). RT-PCR showed mRNA expression of ENaC subunits Scnn1a, Scnn1b, and Scnn1g in urethral epithelium and isolated UBC. Scnn1a could also be detected by next generation sequencing in 4/6 (66%) single UBC, two of them also expressed the bitter receptor Tas2R108. Strong expression of Scnn1a was seen in some urothelial umbrella cells and in 65% of UBC (30/46 cells) in a Scnn1a reporter mouse strain. Intracellular [Ca2+] was recorded in isolated UBC stimulated with the bitter substance denatonium benzoate (25 mM), ATP (0.5 mM) and NaCl (50 mM, on top of 145 mM Na+ and 153 mM Cl− baseline in buffer); mannitol (150 mM) served as osmolarity control. NaCl, but not mannitol, evoked an increase in intracellular [Ca2+] in 70% of the tested UBC. The NaCl-induced effect was blocked by the ENaC inhibitor amiloride (IC50 = 0.47 μM). When responses to both NaCl and denatonium were tested, all three possible positive response patterns occurred in a balanced distribution: 42% NaCl only, 33% denatonium only, 25% to both stimuli. A similar reaction pattern was observed with ATP and NaCl as test stimuli. About 22% of the UBC reacted to all three stimuli. Thus, NaCl evokes calcium responses in several UBC, likely involving an amiloride-sensitive channel containing α-ENaC. This feature does not define a new subpopulation of UBC, but rather emphasizes their polymodal character. The actual function of α-ENaC in cholinergic UBC—salt perception, homeostatic ion transport, mechanoreception—remains to be determined.
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Affiliation(s)
- Chrissy Kandel
- Institute for Anatomy and Cell Biology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Patricia Schmidt
- Institute for Anatomy and Cell Biology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Alexander Perniss
- Institute for Anatomy and Cell Biology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Maryam Keshavarz
- Institute for Anatomy and Cell Biology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Paul Scholz
- Department of Cell Physiology, Ruhr-University Bochum, Bochum, Germany
| | - Sabrina Osterloh
- Department of Cell Physiology, Ruhr-University Bochum, Bochum, Germany
| | - Mike Althaus
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Wolfgang Kummer
- Institute for Anatomy and Cell Biology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Klaus Deckmann
- Institute for Anatomy and Cell Biology, Justus-Liebig-University Giessen, Giessen, Germany
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164
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Zhao C, Crosby J, Lv T, Bai D, Monia BP, Guo S. Antisense oligonucleotide targeting of mRNAs encoding ENaC subunits α, β, and γ improves cystic fibrosis-like disease in mice. J Cyst Fibros 2018; 18:334-341. [PMID: 30100257 DOI: 10.1016/j.jcf.2018.07.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 07/11/2018] [Accepted: 07/20/2018] [Indexed: 12/19/2022]
Abstract
BACKGROUND The epithelial sodium channel ENaC consists of three subunits encoded by Scnn1a, Scnn1b, and Scnn1g and increased sodium absorption through this channel is hypothesized to lead to mucus dehydration and accumulation in cystic fibrosis (CF) patients. METHODS We identified potent and specific antisense oligonucleotides (ASOs) targeting mRNAs encoding the ENaC subunits and evaluated these ASOs in mouse models of CF-like lung disease. RESULTS ASOs designed to target mRNAs encoding each ENaC subunit or a control ASO were administered directly into the lungs of mice. The reductions in ENaC subunits correlated well with a reduction in amiloride sensitive channel conductance. In addition, levels of mucus markers Gob5, AGR2, Muc5ac, and Muc5b, periodic acid-Schiff's reagent (PAS) goblet cell staining, and neutrophil recruitment were reduced and lung function was improved when levels of any of the ENaC subunits were decreased. CONCLUSIONS Delivery of ASOs targeting mRNAs encoding each of the three ENaC subunits directly into the lung improved disease phenotypes in a mouse model of CF-like lung disease. These findings suggest that targeting ENaC subunits could be an effective approach for the treatment of CF.
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Affiliation(s)
- Chenguang Zhao
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA.
| | - Jeff Crosby
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Tinghong Lv
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Dong Bai
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Brett P Monia
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Shuling Guo
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
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165
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Dagenais A, Desjardins J, Shabbir W, Roy A, Filion D, Sauvé R, Berthiaume Y. Loss of barrier integrity in alveolar epithelial cells downregulates ENaC expression and activity via Ca 2+ and TRPV4 activation. Pflugers Arch 2018; 470:1615-1631. [PMID: 30088081 DOI: 10.1007/s00424-018-2182-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 06/14/2018] [Accepted: 07/09/2018] [Indexed: 01/08/2023]
Abstract
The epithelial Na channel (ENaC) plays an essential role in lung physiology by modulating the amount of liquid lining the respiratory epithelium. Here, we tested the effect of breaking alveolar epithelial cell barrier integrity on ENaC expression and function. We found that either mechanical wounding by scratching the monolayer or disruption of tight junction with EDTA induced a ~ 50% decrease of α,β and γENaC mRNA expression and an 80% reduction of ENaC short-circuit current (Isc) at 6 h. Scratching the cell monolayer generated a Ca2+ wave that spread from the margin of the scratch to distant cells. Pretreatment with BAPTA-AM, an intracellular Ca2+ chelator, abolished the effect of mechanical wounding and EDTA on αENaC mRNA expression, suggesting that [Ca2+]i is important for this modulation. We tested the hypothesis that a mechanosensitive channel such as TRPV4, a cationic channel known to increase [Ca2+]i, could mediate this effect. Activation of the channel with the TRPV4 specific agonist GSK-1016790A (GSK) decreased αENAC mRNA expression and almost completely abolished ENaC Isc. Pretreatment of alveolar epithelial cells with HC-067047 (HC0), a specific TRPV4 antagonist, reduced the extent of αENAC mRNA downregulation by mechanical wounding and EDTA. Altogether, our results suggest that mechanical stress induced by wounding or TRPV4-mediated loss of tight junction increases [Ca2+]i and elicits a Ca2+ wave that affects ENaC expression and function away from the site of injury. These data are important to better understand how Ca2+ signaling affects lung liquid clearance in injured lungs.
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Affiliation(s)
- André Dagenais
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montreal, Quebec, H2W 1R7, Canada.
- Département de médecine, Université de Montréal, Montreal, Quebec, Canada.
| | - Julie Desjardins
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montreal, Quebec, H2W 1R7, Canada
| | - Waheed Shabbir
- Institute of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | - Antoine Roy
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montreal, Quebec, H2W 1R7, Canada
| | - Dominic Filion
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montreal, Quebec, H2W 1R7, Canada
| | - Rémy Sauvé
- Département de pharmacologie et physiologie, Université de Montréal, Montreal, Quebec, Canada
| | - Yves Berthiaume
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montreal, Quebec, H2W 1R7, Canada
- Département de médecine, Université de Montréal, Montreal, Quebec, Canada
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Abstract
INTRODUCTION Cystic fibrosis is an autosomal recessive disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that codes for the CFTR anion channel. In the absence of functional CFTR, the epithelial Na+ channel is also dysregulated. Airway surface liquid (ASL) hydration is maintained by a balance between epithelial sodium channel (ENaC)-led Na+ absorption and CFTR-dependent anion secretion. This finely tuned homeostatic mechanism is required to maintain sufficient airway hydration to permit the efficient mucus clearance necessary for a sterile lung environment. In CF airways, the lack of CFTR and increased ENaC activity lead to ASL/mucus dehydration that causes mucus obstruction, neutrophilic infiltration, and chronic bacterial infection. Rehydration of ASL/mucus in CF airways can be achieved by inhibiting Na+ absorption with pharmacological inhibitors of ENaC. Areas covered: In this review, we discuss ENaC structure and function and its role in CF lung disease and focus on ENaC inhibition as a potential therapeutic target to rehydrate CF mucus. We also discuss the failure of the first generation of pharmacological inhibitors of ENaC and recent alternate strategies to attenuate ENaC activity in the CF lung. Expert opinion: ENaC is an attractive therapeutic target to rehydrate CF ASL that may serve as a monotherapy or function in parallel with other treatments. Given the increased number of strategies being employed to inhibit ENaC, this is an exciting and optimistic time to be in this field.
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Affiliation(s)
- Patrick J Moore
- a Marsico Lung Institute , University of North Carolina , Chapel Hill , NC , USA
| | - Robert Tarran
- a Marsico Lung Institute , University of North Carolina , Chapel Hill , NC , USA.,b Department of Cell Biology & Physiology , University of North Carolina , Chapel Hill , NC , USA
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167
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Figueira MF, Webster MJ, Tarran R. Rebuttal from Miriam F. Figueira, Megan J. Webster and Robert Tarran. J Physiol 2018; 596:3443-3444. [PMID: 30014480 DOI: 10.1113/jp276146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 04/16/2018] [Indexed: 01/12/2023] Open
Affiliation(s)
- Miriam F Figueira
- Cystic Fibrosis Center/Marsico Lung Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Megan J Webster
- Cystic Fibrosis Center/Marsico Lung Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Robert Tarran
- Cystic Fibrosis Center/Marsico Lung Institute, University of North Carolina, Chapel Hill, NC 27599, USA.,Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
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168
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Tingskov SJ, Kwon TH, Frøkiær J, Nørregaard R. Tamoxifen Decreases Lithium-Induced Natriuresis in Rats With Nephrogenic Diabetes Insipidus. Front Physiol 2018; 9:903. [PMID: 30050465 PMCID: PMC6052323 DOI: 10.3389/fphys.2018.00903] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [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: 04/16/2018] [Accepted: 06/21/2018] [Indexed: 11/13/2022] Open
Abstract
Lithium is widely used in the treatment of bipolar affective disorders, but often causes nephrogenic diabetes insipidus (NDI), a condition characterized by a severe urinary concentrating defect. Lithium-induced NDI is associated with dysregulation of the amiloride-sensitive epithelial sodium channel (ENaC), which is essential for renal sodium reabsorption. Sex hormones have been shown to affect the expression of aquaporin-2 (AQP2) and sodium transporters. Therefore, we evaluated whether tamoxifen (TAM), a selective estrogen receptor modulator (SERM), would affect lithium-induced dysregulation of ENaC subunits and natriuresis. Rats were fed with lithium-containing food for 2 weeks to induce NDI and natriuresis. TAM was administered daily via gastric gavage after 1 week of lithium administration. Lithium treatment alone resulted in increased urinary sodium excretion and significant reduction of βENaC and γENaC at both RNA and protein levels. In addition, the plasma sodium level reduced after lithium treatment. Administration of TAM prevented increased urinary sodium excretion as well as attenuated the downregulation of βENaC and γENaC. Consistent with these findings, immunohistochemistry (IHC) showed stronger labeling of βENaC and γENaC subunits in the apical domain of the collecting duct cells in the cortical tissue of lithium-fed rats treated with TAM. Other major sodium transporters including NaPi-2, NKCC2, Na/K-ATPase, and NHE3, are believed not to have an effect on the increased urinary sodium excretion since their expression increased or was unchanged after treatment with lithium. In conclusion, the results demonstrated that TAM rescued the adverse effects of the lithium-induced increase in fractional excretion of sodium after the establishment of lithium-induced NDI.
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Affiliation(s)
| | - Tae-Hwan Kwon
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - Jørgen Frøkiær
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Rikke Nørregaard
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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169
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Ivy JR, Evans LC, Moorhouse R, Richardson RV, Al-Dujaili EAS, Flatman PW, Kenyon CJ, Chapman KE, Bailey MA. Renal and Blood Pressure Response to a High-Salt Diet in Mice With Reduced Global Expression of the Glucocorticoid Receptor. Front Physiol 2018; 9:848. [PMID: 30038578 PMCID: PMC6046455 DOI: 10.3389/fphys.2018.00848] [Citation(s) in RCA: 12] [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: 01/12/2018] [Accepted: 06/14/2018] [Indexed: 01/02/2023] Open
Abstract
Salt-sensitive hypertension is common in glucocorticoid excess. Glucocorticoid resistance also presents with hypercortisolemia and hypertension but the relationship between salt intake and blood pressure (BP) is not well defined. GRβgeo/+ mice have global glucocorticoid receptor (GR) haploinsufficiency and increased BP. Here we examined the effect of high salt diet on BP, salt excretion and renal blood flow in GRβgeo/+mice. Basal BP was ∼10 mmHg higher in male GRβgeo/+ mice than in GR+/+ littermates. This modest increase was amplified by ∼10 mmHg following a high-salt diet in GRβgeo/+ mice. High salt reduced urinary aldosterone excretion but increased renal mineralocorticoid receptor expression in both genotypes. Corticosterone, and to a lesser extent deoxycorticosterone, excretion was increased in GRβgeo/+ mice following a high-salt challenge, consistent with enhanced 24 h production. GR+/+ mice increased fractional sodium excretion and reduced renal vascular resistance during the high salt challenge, retaining neutral sodium balance. In contrast, sodium excretion and renal vascular resistance did not adapt to high salt in GRβgeo/+ mice, resulting in transient sodium retention and sustained hypertension. With high-salt diet, Slc12a3 and Scnn1a mRNAs were higher in GRβgeo/+ than controls, and this was reflected in an exaggerated natriuretic response to thiazide and benzamil, inhibitors of NCC and ENaC, respectively. Reduction in GR expression causes salt-sensitivity and an adaptive failure of the renal vasculature and tubule, most likely reflecting sustained mineralocorticoid receptor activation. This provides a mechanistic basis to understand the hypertension associated with loss-of-function polymorphisms in GR in the context of habitually high salt intake.
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Affiliation(s)
- Jessica R Ivy
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Louise C Evans
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Rebecca Moorhouse
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Rachel V Richardson
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Emad A S Al-Dujaili
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Peter W Flatman
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Christopher J Kenyon
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Karen E Chapman
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Matthew A Bailey
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
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170
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Ray EC, Miller RG, Demko JE, Costacou T, Kinlough CL, Demko CL, Unruh ML, Orchard TJ, Kleyman TR. Urinary Plasmin(ogen) as a Prognostic Factor for Hypertension. Kidney Int Rep 2018; 3:1434-1442. [PMID: 30450470 PMCID: PMC6224670 DOI: 10.1016/j.ekir.2018.06.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [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: 02/20/2018] [Revised: 05/25/2018] [Accepted: 06/25/2018] [Indexed: 12/05/2022] Open
Abstract
Introduction Plasmin and its precursor, plasminogen, are detectable in urine from patients with glomerular disease. Urinary plasmin(ogen) levels correlate with blood pressure (BP) and may contribute to renal Na+ retention by activating the epithelial Na+ channel (ENaC). In a longitudinal nested-cohort study, we asked whether urinary plasmin(ogen) levels predict subsequent increase in BP, incident hypertension, or mortality in subjects with type I diabetes, who often develop proteinuria. Methods The Pittsburgh Epidemiology of Diabetes Complications (EDC) study followed up type I diabetic subjects for 25 years. Urine specimens from 70 subjects with a spectrum of baseline urinary albumin levels were examined. Outcomes included increased BP after 2 years (≥1 SD over baseline systolic or diastolic BP, examined via logistic regression), 25-year incident hypertension (≥140/90 mm Hg or initiating BP-lowering medications), and all-cause or cardiovascular mortality, examined using Cox regression. Results Subjects experiencing a 2-year increase in BP had higher baseline urinary plasmin(ogen)/creatinine levels (uPl/Cr) than other subjects (P = 0.04); the difference in baseline urinary albumin/creatinine levels (uAlb/Cr) was similar (P = 0.07). Baseline uPl/Cr was associated with increased 25-year hypertension incidence (hazard ratio = 2.05, P = 0.001), all-cause mortality (HR = 2.05, P = 0.01) and cardiovascular mortality (HR = 3.30, P = 0.005), although not independent of uAlb/Cr. Conclusion This is the first long-term prospective study addressing clinical outcomes associated with increased urinary plasmin(ogen). Findings are consistent with a role for plasmin(ogen) in promoting increased BP, but also demonstrate the difficulty in distinguishing effects due to plasmin(ogen) from those of albuminuria.
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Affiliation(s)
- Evan C. Ray
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Correspondence: Evan C. Ray, Renal-Electrolyte Division, A915 Scaife Hall, 3550 Terrace Street, Pittsburgh, Pennsylvania 15261, USA.
| | - Rachel G. Miller
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - John E. Demko
- University of California San Francisco, San Francisco, California, USA
| | - Tina Costacou
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Carol L. Kinlough
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Casey L. Demko
- University of California San Francisco, San Francisco, California, USA
| | - Mark L. Unruh
- Department of Internal Medicine, University of New Mexico, Albuquerque, New Mexico, USA
- Nephrology Section, New Mexico Veterans Hospital, Albuquerque, New Mexico, USA
| | - Trevor J. Orchard
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Thomas R. Kleyman
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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171
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Manning JA, Kumar S. Physiological Functions of Nedd4-2: Lessons from Knockout Mouse Models. Trends Biochem Sci 2018; 43:635-647. [PMID: 30056838 DOI: 10.1016/j.tibs.2018.06.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [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: 04/05/2018] [Revised: 05/11/2018] [Accepted: 06/04/2018] [Indexed: 01/10/2023]
Abstract
Protein modification by ubiquitination plays a key evolutionarily conserved role in regulating membrane proteins. Nedd4-2, a ubiquitin ligase, targets membrane proteins such as ion channels and transporters for ubiquitination. This Nedd4-2-mediated ubiquitination provides a crucial step in controlling the membrane availability of these proteins, thus affecting their signaling and physiological outcomes. In one well-studied example, Nedd4-2 fine-tunes the physiological function of the epithelial sodium channel (ENaC), thus modulating Na+ reabsorption by epithelia to maintain whole-body Na+ homeostasis. This review summarizes the key signaling pathways regulated by Nedd4-2 and the possible implications of such regulation in various pathologies.
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Affiliation(s)
- Jantina A Manning
- Centre for Cancer Biology, University of South Australia and SA Pathology, GPO Box 2471, Adelaide, SA 5001, Australia
| | - Sharad Kumar
- Centre for Cancer Biology, University of South Australia and SA Pathology, GPO Box 2471, Adelaide, SA 5001, Australia.
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172
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Ware AW, Cheung TT, Rasulov S, Burstein E, McDonald FJ. Epithelial Na + Channel: Reciprocal Control by COMMD10 and Nedd4-2. Front Physiol 2018; 9:793. [PMID: 29997525 PMCID: PMC6028986 DOI: 10.3389/fphys.2018.00793] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 06/06/2018] [Indexed: 11/25/2022] Open
Abstract
Optimal function of the epithelial sodium channel (ENaC) in the distal nephron is key to the kidney’s long-term control of salt homeostasis and blood pressure. Multiple pathways alter ENaC cell surface populations, including correct processing and trafficking in the secretory pathway to the cell surface, and retrieval from the cell surface through ubiquitination by the ubiquitin ligase Nedd4-2, clathrin-mediated endocytosis, and sorting in the endosomal system. Members of the Copper Metabolism Murr1 Domain containing (COMMD) family of 10 proteins are known to interact with ENaC. COMMD1, 3 and 9 have been shown to down-regulate ENaC, most likely through Nedd4-2, however, the other COMMD family members remain uncharacterized. To investigate the effects of the COMMD10 protein on ENaC trafficking and function, the interaction of ENaC and COMMD10 was confirmed. Stable COMMD10 knockdown in Fischer rat thyroid epithelia decreased ENaC current and this decreased current was associated with increased Nedd4-2 protein, a known negative regulator of ENaC. However, inhibition of Nedd4-2’s ubiquitination of ENaC was only able to partially rescue the observed reduction in current. Stable COMMD10 knockdown results in defects both in endocytosis and recycling of transferrin suggesting COMMD10 likely interacts with multiple pathways to regulate ENaC and therefore could be involved in the long-term control of blood pressure.
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Affiliation(s)
- Adam W Ware
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Tanya T Cheung
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Sahib Rasulov
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Ezra Burstein
- Department of Internal Medicine and Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Fiona J McDonald
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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173
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Yang L, Xu S, Guo X, Uchida S, Weinstein AM, Wang T, Palmer LG. Regulation of renal Na transporters in response to dietary K. Am J Physiol Renal Physiol 2018; 315:F1032-F1041. [PMID: 29923764 DOI: 10.1152/ajprenal.00117.2018] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [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: 11/22/2022] Open
Abstract
Changes in the expression of Na transport proteins were measured in the kidneys of mice with increased dietary K intake for 1 wk. The epithelial Na channel (ENaC) was upregulated, with enhanced expression of full-length and cleaved forms of α-ENaC and cleaved γ-ENaC. At the same time, the amount of the NaCl cotransporter NCC and its phosphorylated form decreased by ~50% and ~80%, respectively. The expression of the phosphorylated form of the Na-K-2Cl cotransporter NKCC2 also decreased, despite an increase in overall protein content. The effect was stronger in males (80%) than in females (40%). This implies that less Na+ is reabsorbed in the thick ascending limb of Henle's loop and distal convoluted tubule along with Cl-, whereas more is reabsorbed in the aldosterone-sensitive distal nephron in exchange for secreted K+. The abundance of the proximal tubule Na/H exchanger NHE3 decreased by ~40%, with similar effects in males and females. Time-course studies indicated that NCC and NHE3 proteins decreased progressively over 7 days on a high-K diet. Expression of mRNA encoding these proteins increased, implying that the decreased protein levels resulted from decreased rates of synthesis or increased rates of degradation. The potential importance of changes in NHE3, NKCC2, and NCC in promoting K+ excretion was assessed with a mathematical model. Simulations indicated that decreased NHE3 produced the largest effect. Regulation of proximal tubule Na+ transport may play a significant role in achieving K homeostasis.
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Affiliation(s)
- Lei Yang
- Department of Physiology and Biophysics, Weill Medical College of Cornell University , New York, New York
| | - Shuhua Xu
- Department of Cellular and Molecular Physiology, Yale University , New Haven, Connecticut
| | - Xiaoyun Guo
- Department of Cellular and Molecular Physiology, Yale University , New Haven, Connecticut
| | - Shinichi Uchida
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Alan M Weinstein
- Department of Physiology and Biophysics, Weill Medical College of Cornell University , New York, New York
| | - Tong Wang
- Department of Cellular and Molecular Physiology, Yale University , New Haven, Connecticut
| | - Lawrence G Palmer
- Department of Physiology and Biophysics, Weill Medical College of Cornell University , New York, New York
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174
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Barbaro NR, Foss JD, Kryshtal DO, Tsyba N, Kumaresan S, Xiao L, Mernaugh RL, Itani HA, Loperena R, Chen W, Dikalov S, Titze JM, Knollmann BC, Harrison DG, Kirabo A. Dendritic Cell Amiloride-Sensitive Channels Mediate Sodium-Induced Inflammation and Hypertension. Cell Rep 2018; 21:1009-1020. [PMID: 29069584 PMCID: PMC5674815 DOI: 10.1016/j.celrep.2017.10.002] [Citation(s) in RCA: 168] [Impact Index Per Article: 28.0] [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: 02/23/2017] [Revised: 07/07/2017] [Accepted: 09/29/2017] [Indexed: 02/02/2023] Open
Abstract
Sodium accumulates in the interstitium and promotes inflammation through poorly defined mechanisms. We describe a pathway by which sodium enters dendritic cells (DCs) through amiloride-sensitive channels including the alpha and gamma subunits of the epithelial sodium channel and the sodium hydrogen exchanger 1. This leads to calcium influx via the sodium calcium exchanger, activation of protein kinase C (PKC), phosphorylation of p47phox, and association of p47phox with gp91phox. The assembled NADPH oxidase produces superoxide with subsequent formation of immunogenic isolevuglandin (IsoLG)-protein adducts. DCs activated by excess sodium produce increased interleukin-1β (IL-1β) and promote T cell production of cytokines IL-17A and interferon gamma (IFN-γ). When adoptively transferred into naive mice, these DCs prime hypertension in response to a sub-pressor dose of angiotensin II. These findings provide a mechanistic link between salt, inflammation, and hypertension involving increased oxidative stress and IsoLG production in DCs.
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Affiliation(s)
- Natalia R Barbaro
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jason D Foss
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Dmytro O Kryshtal
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Nikita Tsyba
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Shivani Kumaresan
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Liang Xiao
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | | | - Hana A Itani
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Roxana Loperena
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Wei Chen
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Sergey Dikalov
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jens M Titze
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Bjorn C Knollmann
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - David G Harrison
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Annet Kirabo
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.
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175
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Moore PJ, Reidel B, Ghosh A, Sesma J, Kesimer M, Tarran R. Cigarette smoke modifies and inactivates SPLUNC1, leading to airway dehydration. FASEB J 2018; 32:fj201800345R. [PMID: 29890087 PMCID: PMC6219833 DOI: 10.1096/fj.201800345r] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 05/21/2018] [Indexed: 01/14/2023]
Abstract
Chronic obstructive pulmonary disease (COPD) is a growing cause of morbidity and mortality worldwide. Cigarette smoke (CS) exposure, a major cause of COPD, dysregulates airway epithelial ion transport and diminishes airway surface liquid (ASL) volume. Short palate lung and nasal epithelial clone 1 (SPLUNC1) is secreted into the airway lumen where it maintains airway hydration via interactions with the epithelial Na+ channel (ENaC). Although ASL hydration is dysregulated in CS-exposed/COPD airways, effects of CS on SPLUNC1 have not been elucidated. We hypothesized that CS alters SPLUNC1 activity, therefore contributing to ASL dehydration. CS exposure caused irreversible SPLUNC1 aggregation and prevented SPLUNC1 from internalizing ENaC and maintaining ASL hydration. Proteomic analysis revealed αβ-unsaturated aldehyde modifications to SPLUNC1's cysteine residues. Removal of these cysteines prevented SPLUNC1 from regulating ENaC/ASL volume. In contrast, SPX-101, a peptide mimetic of natural SPLUNC1, that internalizes ENaC, but does not contain cysteines was unaffected by CS. SPX-101 increased ASL hydration and attenuated ENaC activity in airway cultures after CS exposure and prolonged survival in a chronic airway disease model. These findings suggest that the CS-induced defects in SPLUNC1 can be circumvented, thus making SPX-101 a novel candidate for the treatment of mucus dehydration in COPD. -Moore, P. J., Reidel, B., Ghosh, A., Sesma, J., Kesimer, M., Tarran, R. Cigarette smoke modifies and inactivates SPLUNC1, leading to airway dehydration.
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Affiliation(s)
- Patrick J. Moore
- Marsico Lung Institute, University of North Carolina at Chapel Hill, North Carolina, USA
| | - Boris Reidel
- Marsico Lung Institute, University of North Carolina at Chapel Hill, North Carolina, USA
| | - Arunava Ghosh
- Marsico Lung Institute, University of North Carolina at Chapel Hill, North Carolina, USA
| | | | - Mehmet Kesimer
- Marsico Lung Institute, University of North Carolina at Chapel Hill, North Carolina, USA
| | - Robert Tarran
- Marsico Lung Institute, University of North Carolina at Chapel Hill, North Carolina, USA
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, North Carolina, USA
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176
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Hinrichs GR, Mortensen LA, Jensen BL, Bistrup C. Amiloride resolves resistant edema and hypertension in a patient with nephrotic syndrome; a case report. Physiol Rep 2018; 6:e13743. [PMID: 29939487 PMCID: PMC6016639 DOI: 10.14814/phy2.13743] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 05/29/2018] [Accepted: 05/29/2018] [Indexed: 01/17/2023] Open
Abstract
Sodium and fluid retention is a hallmark and a therapeutic challenge of the nephrotic syndrome (NS). Studies support the "overfill" theory of NS with pathophysiological proteolytic activation of the epithelial sodium channel (ENaC) which explains the common observation of suppressed renin -angiotensin system and poor therapeutic response to ACE inhibitors. Blockade of ENaC by the diuretic amiloride would be a rational intervention compared to the traditionally used loop diuretics. We describe a 38-year-old male patient with type1 diabetes who developed severe hypertension (200/140 mmHg), progressive edema (of at least 10 L), and overt proteinuria (18.5 g/24 h), despite combined administration of five antihypertensive drugs. Addition of amiloride (5 mg/day) to treatment resulted in resolution of edema, weight loss of 7 kg, reduction in blood pressure (150/100-125/81 mmHg), increased 24 h urinary sodium excretion (127-165 mmol/day), decreased eGFR (41-29 mL/min), and increased plasma potassium concentration (4.6-7.8 mmol/L). Blocking of ENaC mobilizes nephrotic edema and lowers blood pressure in NS. However, acute kidney injury and dangerous hyperkalemia is a potential risk if amiloride is added to multiple other antihypertensive medications as ACEi and spironolactone. The findings support that ENaC is active in NS and is a relevant target in adult NS patients.
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Affiliation(s)
- Gitte R. Hinrichs
- Department of Cardiovascular and Renal ResearchUniversity of Southern DenmarkOdenseDenmark
| | | | - Boye L. Jensen
- Department of Cardiovascular and Renal ResearchUniversity of Southern DenmarkOdenseDenmark
| | - Claus Bistrup
- Department of NephrologyOdense University HospitalOdenseDenmark
- Department of Clinical ResearchUniversity of Southern DenmarkOdenseDenmark
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177
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Turan I, Kotan LD, Tastan M, Gurbuz F, Topaloglu AK, Yuksel B. Molecular genetic studies in a case series of isolated hypoaldosteronism due to biosynthesis defects or aldosterone resistance. Clin Endocrinol (Oxf) 2018; 88:799-805. [PMID: 29582446 DOI: 10.1111/cen.13603] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 03/21/2018] [Accepted: 03/21/2018] [Indexed: 01/22/2023]
Abstract
BACKGROUND AND AIM Hypoaldosteronism is associated with either insufficient aldosterone production or aldosterone resistance (pseudohypoaldosteronism). Patients with aldosterone defects typically present with similar symptoms and findings, which include failure to thrive, vomiting, hyponatremia, hyperkalemia and metabolic acidosis. Accurate diagnosis of these clinical conditions therefore can be challenging. Molecular genetic analyses can help to greatly clarify this complexity. The aim of this study was to obtain an overview of the clinical and genetic characteristics of patients with aldosterone defects due to biosynthesis defects or aldosterone resistance. DESIGN AND PATIENTS We investigated the clinical and molecular genetic features of 8 consecutive patients with a clinical picture of aldosterone defects seen in our clinics during the period of May 2015 through October 2017. We screened CYP11B2 for aldosterone synthesis defects and NR3C2 and the three EnaC subunits (SCNN1A, SCNN1B and SCNN1G) for aldosterone resistance. RESULTS We found 4 novel and 2 previously reported mutations in the genes CYP11B2, NR3C2, SCNN1A and SCNN1G in 9 affected individuals from 7 unrelated families. CONCLUSION Molecular genetic investigations can help confidently diagnose these conditions and clarify the pathogenicity of aldosterone defects. This study may expand the clinical and genetic correlations of defects in aldosterone synthesis or resistance.
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Affiliation(s)
- Ihsan Turan
- Faculty of Medicine, Division of Pediatric Endocrinology, Cukurova University, Adana, Turkey
| | - Leman Damla Kotan
- Faculty of Medicine, Division of Pediatric Endocrinology, Cukurova University, Adana, Turkey
| | - Mehmet Tastan
- Faculty of Medicine, Division of Pediatric Endocrinology, Cukurova University, Adana, Turkey
| | - Fatih Gurbuz
- Faculty of Medicine, Division of Pediatric Endocrinology, Cukurova University, Adana, Turkey
| | - Ali Kemal Topaloglu
- Faculty of Medicine, Division of Pediatric Endocrinology, Cukurova University, Adana, Turkey
| | - Bilgin Yuksel
- Faculty of Medicine, Division of Pediatric Endocrinology, Cukurova University, Adana, Turkey
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178
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Yang YJ, Kim J, Kwock CK. Association of Genetic Variation in the Epithelial Sodium Channel Gene with Urinary Sodium Excretion and Blood Pressure. Nutrients 2018; 10:E612. [PMID: 29757959 DOI: 10.3390/nu10050612] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 05/10/2018] [Accepted: 05/11/2018] [Indexed: 11/17/2022] Open
Abstract
This study was performed to investigate whether genetic variation in the epithelial sodium channel (ENaC) is associated with 24-h urinary sodium excretion and blood pressure. A total of 3345 participants of the KoGES_Ansan and Ansung study were eligible for this study. Genomic DNA samples were isolated from peripheral blood and genotyped on the Affymetrix Genome-Wide Human SNP Array 5.0. Thirty-four single nucleotide polymorphisms (SNPs) were extracted for gene regions (SCNN1A, SCNN1B, and SCNN1G) as additive components by using Plink. Twenty-four-hour sodium excretions were estimated from spot urine samples using the Tanaka formula. The general linear model (GLM) was applied to assess the association between SNPs and urinary sodium excretion or blood pressure. In the SCNN1G gene, six SNPs (rs4073291, rs12934362, rs7404408, rs4494543, rs5735, and rs6497657) were significantly different in 24-h urinary sodium excretion according to gene variants. However, no difference was found in blood pressure among participants with gene variants of ENaC. Our finding indicated that 24-h urinary sodium excretions were different according to variants of the SCNN1G gene in large samples. Further studies to replicate these findings are warranted.
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179
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Puga Molina LC, Pinto NA, Torres NI, González-Cota AL, Luque GM, Balestrini PA, Romarowski A, Krapf D, Santi CM, Treviño CL, Darszon A, Buffone MG. CFTR/ ENaC-dependent regulation of membrane potential during human sperm capacitation is initiated by bicarbonate uptake through NBC. J Biol Chem 2018; 293:9924-9936. [PMID: 29743243 DOI: 10.1074/jbc.ra118.003166] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 04/29/2018] [Indexed: 12/16/2022] Open
Abstract
To fertilize an egg, sperm must reside in the female reproductive tract to undergo several maturational changes that are collectively referred to as capacitation. From a molecular point of view, the HCO3--dependent activation of the atypical soluble adenylyl cyclase (ADCY10) is one of the first events that occurs during capacitation and leads to the subsequent cAMP-dependent activation of protein kinase A (PKA). Capacitation is also accompanied by hyperpolarization of the sperm plasma membrane. We previously reported that PKA activation is necessary for CFTR (cystic fibrosis transmembrane conductance regulator channel) activity and for the modulation of membrane potential (Em). However, the main HCO3- transporters involved in the initial transport and the PKA-dependent Em changes are not well known nor characterized. Here, we analyzed how the activity of CFTR regulates Em during capacitation and examined its relationship with an electrogenic Na+/HCO3- cotransporter (NBC) and epithelial Na+ channels (ENaCs). We observed that inhibition of both CFTR and NBC decreased HCO3- influx, resulting in lower PKA activity, and that events downstream of the cAMP activation of PKA are essential for the regulation of Em. Addition of a permeable cAMP analog partially rescued the inhibitory effects caused by these inhibitors. HCO3- also produced a rapid membrane hyperpolarization mediated by ENaC channels, which contribute to the regulation of Em during capacitation. Altogether, we demonstrate for the first time, that NBC cotransporters and ENaC channels are essential in the CFTR-dependent activation of the cAMP/PKA signaling pathway and Em regulation during human sperm capacitation.
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Affiliation(s)
- Lis C Puga Molina
- From the Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1425FQB Buenos Aires, Argentina
| | - Nicolás A Pinto
- From the Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1425FQB Buenos Aires, Argentina
| | - Nicolás I Torres
- From the Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1425FQB Buenos Aires, Argentina
| | - Ana L González-Cota
- the Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Guillermina M Luque
- From the Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1425FQB Buenos Aires, Argentina
| | - Paula A Balestrini
- From the Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1425FQB Buenos Aires, Argentina
| | - Ana Romarowski
- From the Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1425FQB Buenos Aires, Argentina
| | - Dario Krapf
- the Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET-UNR, Rosario 2000, Argentina, and
| | - Celia M Santi
- the Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Claudia L Treviño
- the Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, 62210 Morelos, México
| | - Alberto Darszon
- the Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, 62210 Morelos, México
| | - Mariano G Buffone
- From the Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1425FQB Buenos Aires, Argentina,
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180
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Abstract
Inflammatory bowel diseases broadly categorized into Crohn's disease (CD) and ulcerative colitis (UC), are chronic inflammatory disorders of the gastrointestinal tract with increasing prevalence worldwide. The etiology of the disease is complex and involves a combination of genetic, environmental, immunological and gut microbial factors. Recurring and bloody diarrhea is the most prevalent and debilitating symptom in IBD. The pathogenesis of IBD-associated diarrhea is multifactorial and is essentially an outcome of mucosal damage caused by persistent inflammation resulting in dysregulated intestinal ion transport, impaired epithelial barrier function and increased accessibility of the pathogens to the intestinal mucosa. Altered expression and/or function of epithelial ion transporters and channels is the principle cause of electrolyte retention and water accumulation in the intestinal lumen leading to diarrhea in IBD. Aberrant barrier function further contributes to diarrhea via leak-flux mechanism. Mucosal penetration of enteric pathogens promotes dysbiosis and exacerbates the underlying immune system further perpetuating IBD associated-tissue damage and diarrhea. Here, we review the mechanisms of impaired ion transport and loss of epithelial barrier function contributing to diarrhea associated with IBD.
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Affiliation(s)
- Arivarasu N Anbazhagan
- a Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago , Chicago , IL , USA
| | - Shubha Priyamvada
- a Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago , Chicago , IL , USA
| | - Waddah A Alrefai
- a Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago , Chicago , IL , USA.,b Jesse Brown VA Medical Center , Chicago , IL , USA
| | - Pradeep K Dudeja
- a Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago , Chicago , IL , USA.,b Jesse Brown VA Medical Center , Chicago , IL , USA
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181
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Srisomboon Y, Zaidman NA, Maniak PJ, Deachapunya C, O'Grady SM. P2Y receptor regulation of K2P channels that facilitate K + secretion by human mammary epithelial cells. Am J Physiol Cell Physiol 2018; 314:C627-C639. [PMID: 29365273 DOI: 10.1152/ajpcell.00342.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The objective of this study was to determine the molecular identity of ion channels involved in K+ secretion by the mammary epithelium and to examine their regulation by purinoceptor agonists. Apical membrane voltage-clamp experiments were performed on human mammary epithelial cells where the basolateral membrane was exposed to the pore-forming antibiotic amphotericin B dissolved in a solution with intracellular-like ionic composition. Addition of the Na+ channel inhibitor benzamil reduced the basal current, consistent with inhibition of Na+ uptake across the apical membrane, whereas the KCa3.1 channel blocker TRAM-34 produced an increase in current resulting from inhibition of basal K+ efflux. Treatment with two-pore potassium (K2P) channel blockers quinidine, bupivacaine and a selective TASK1/TASK3 inhibitor (PK-THPP) all produced concentration-dependent inhibition of apical K+ efflux. qRT-PCR experiments detected mRNA expression for nine K2P channel subtypes. Western blot analysis of biotinylated apical membranes and confocal immunocytochemistry revealed that at least five K2P subtypes (TWIK1, TREK1, TREK2, TASK1, and TASK3) are expressed in the apical membrane. Apical UTP also increased the current, but pretreatment with the PKC inhibitor GF109203X blocked the response. Similarly, direct activation of PKC with phorbol 12-myristate 13-acetate produced a similar increase in current as observed with UTP. These results support the conclusion that the basal level of K+ secretion involves constitutive activity of apical KCa3.1 channels and multiple K2P channel subtypes. Apical UTP evoked a transient increase in KCa3.1 channel activity, but over time caused persistent inhibition of K2P channel function leading to an overall decrease in K+ secretion.
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Affiliation(s)
| | - Nathan A Zaidman
- Departments of Animal Science, Integrative Biology, and Physiology, University of Minnesota , St. Paul, Minnesota
| | - Peter J Maniak
- Departments of Animal Science, Integrative Biology, and Physiology, University of Minnesota , St. Paul, Minnesota
| | | | - Scott M O'Grady
- Departments of Animal Science, Integrative Biology, and Physiology, University of Minnesota , St. Paul, Minnesota
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182
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Valinsky WC, Touyz RM, Shrier A. Aldosterone, SGK1, and ion channels in the kidney. Clin Sci (Lond) 2018; 132:173-83. [PMID: 29352074 DOI: 10.1042/CS20171525] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [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] [Received: 11/14/2017] [Revised: 12/15/2017] [Accepted: 12/19/2017] [Indexed: 12/14/2022]
Abstract
Hyperaldosteronism, a common cause of hypertension, is strongly connected to Na+, K+, and Mg2+ dysregulation. Owing to its steroidal structure, aldosterone is an active transcriptional modifier when bound to the mineralocorticoid receptor (MR) in cells expressing the enzyme 11β-hydroxysteroid dehydrogenase 2, such as those comprising the aldosterone-sensitive distal nephron (ASDN). One such up-regulated protein, the ubiquitous serum and glucocorticoid regulated kinase 1 (SGK1), has the capacity to modulate the surface expression and function of many classes of renal ion channels, including those that transport Na+ (ENaC), K+ (ROMK/BK), Ca2+ (TRPV4/5/6), Mg2+ (TRPM7/6), and Cl− (ClC-K, CFTR). Here, we discuss the mechanisms by which ASDN expressed channels are up-regulated by SGK1, while highlighting newly discovered pathways connecting aldosterone to nonselective cation channels that are permeable to Mg2+ (TRPM7) or Ca2+ (TRPV4).
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183
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Shuyskiy LS, Levchenko VV, Negulyaev YA, Staruschenko AV, Ilatovskaya DV. Role of the Scaffold Protein MIM in the Actin-Dependent Regulation of Epithelial Sodium Channels ( ENaC). Acta Naturae 2018; 10:97-103. [PMID: 30116621 PMCID: PMC6087825] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Epithelial Sodium Channels (ENaCs) are expressed in different organs and tissues, particularly in the cortical collecting duct (CCD) in the kidney, where they fine tune sodium reabsorption. Dynamic rearrangements of the cytoskeleton are one of the common mechanisms of ENaC activity regulation. In our previous studies, we showed that the actin-binding proteins cortactin and Arp2/3 complex are involved in the cytoskeleton-dependent regulation of ENaC and that their cooperative work decreases a channel's probability of remaining open; however, the specific mechanism of interaction between actin-binding proteins and ENaC is unclear. In this study, we propose a new component for the protein machinery involved in the regulation of ENaC, the missing-in-metastasis (MIM) protein. The MIM protein contains an IMD domain (for interaction with PIP2 -rich plasma membrane regions and Rac GTPases; this domain also possesses F-actin bundling activity), a PRD domain (for interaction with cortactin), and a WH2 domain (interaction with G-actin). The patch-clamp electrophysiological technique in whole-cell configuration was used to test the involvement of MIM in the actin-dependent regulation of ENaC. Co-transfection of ENaC subunits with the wild-type MIM protein (or its mutant forms) caused a significant reduction in ENaC-mediated integral ion currents. The analysis of the F-actin structure after the transfection of MIM plasmids showed the important role played by the domains PRD and WH2 of the MIM protein in cytoskeletal rearrangements. These results suggest that the MIM protein may be a part of the complex of actin-binding proteins which is responsible for the actin-dependent regulation of ENaC in the CCD.
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Affiliation(s)
- L. S. Shuyskiy
- Institute of Cytology of RAS, Tikhoretskij Ave. 4, St. Petersburg, 194064, Russia , Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - V. V. Levchenko
- Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Y. A. Negulyaev
- Institute of Cytology of RAS, Tikhoretskij Ave. 4, St. Petersburg, 194064, Russia , Department of Medical Physics, Peter the Great St. Petersburg Polytechnic University, Politekhnicheskaya Str. 2, St. Petersburg, 195251, Russia
| | - A. V. Staruschenko
- Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - D. V. Ilatovskaya
- Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA , Medical University of South Carolina, Department of Medicine, Division of Nephrology, 96 Jonathan Lucas St, MSC 629 CSB 822, Charleston, SC 29425, USA
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184
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Affiliation(s)
- Jantina A Manning
- a Centre for Cancer Biology, University of South Australia & SA Pathology , Frome Road, Adelaide , SA , Australia
| | - Tanya L Henshall
- a Centre for Cancer Biology, University of South Australia & SA Pathology , Frome Road, Adelaide , SA , Australia
| | - Sharad Kumar
- a Centre for Cancer Biology, University of South Australia & SA Pathology , Frome Road, Adelaide , SA , Australia
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Kamei S, Fujikawa H, Nohara H, Ueno-Shuto K, Maruta K, Nakashima R, Kawakami T, Matsumoto C, Sakaguchi Y, Ono T, Suico MA, Boucher RC, Gruenert DC, Takeo T, Nakagata N, Li JD, Kai H, Shuto T. Zinc Deficiency via a Splice Switch in Zinc Importer ZIP2/SLC39A2 Causes Cystic Fibrosis-Associated MUC5AC Hypersecretion in Airway Epithelial Cells. EBioMedicine 2017; 27:304-316. [PMID: 29289532 PMCID: PMC5828551 DOI: 10.1016/j.ebiom.2017.12.025] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [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: 09/03/2017] [Revised: 12/15/2017] [Accepted: 12/19/2017] [Indexed: 01/02/2023] Open
Abstract
Airway mucus hyperproduction and fluid imbalance are important hallmarks of cystic fibrosis (CF), the most common life-shortening genetic disorder in Caucasians. Dysregulated expression and/or function of airway ion transporters, including cystic fibrosis transmembrane conductance regulator (CFTR) and epithelial sodium channel (ENaC), have been implicated as causes of CF-associated mucus hypersecretory phenotype. However, the contributory roles of other substances and transporters in the regulation of CF airway pathogenesis remain unelucidated. Here, we identified a novel connection between CFTR/ENaC expression and the intracellular Zn2 + concentration in the regulation of MUC5AC, a major secreted mucin that is highly expressed in CF airway. CFTR-defective and ENaC-hyperactive airway epithelial cells specifically and highly expressed a unique, alternative splice isoform of the zinc importer ZIP2/SLC39A2 (ΔC-ZIP2), which lacks the C-terminal domain. Importantly, ΔC-ZIP2 levels correlated inversely with wild-type ZIP2 and intracellular Zn2 + levels. Moreover, the splice switch to ΔC-ZIP2 as well as decreased expression of other ZIPs caused zinc deficiency, which is sufficient for induction of MUC5AC; while ΔC-ZIP2 expression per se induced ENaC expression and function. Thus, our findings demonstrate that the novel splicing switch contributes to CF lung pathology via the novel interplay of CFTR, ENaC, and ZIP2 transporters. Zinc deficiency is a common feature in both CFTR-defective (CF) and ENaC-hyperactive (CF-like) airway epithelial cells. A splice switch from WT-ZIP2 to ΔC-ZIP2 as well as other ZIPs down-regulation caused zinc deficiency in CF and CF-like cells. Lower intracellular Zn2 + levels contributed to CF-associated MUC5AC hypersecretion in airway epithelial cells.
The role of zinc in the pathogenesis of CF lung disease is not well understood. We utilized human CF patient-derived cell lines and primary cells as well as murine CF model, and identified zinc deficiency as a common characteristic in CF models. Down-regulation of several zinc importers (ZIPs) in CF cells caused zinc deficiency, which is sufficient for induction of MUC5AC, a major secreted mucin that exacerbates CF pathogenesis. Especially, strong contribution of ΔC-ZIP2, a novel ZIP2 splice isoform, in the regulation of CF-associated MUC5AC hypersecretion was clearly demonstrated. The study refined the importance of zinc in airway homeostasis.
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Affiliation(s)
- Shunsuke Kamei
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan; Program for Leading Graduate Schools "HIGO (Health life science: Interdisciplinary and Glocal Oriented) Program", Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Haruka Fujikawa
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan; Program for Leading Graduate Schools "HIGO (Health life science: Interdisciplinary and Glocal Oriented) Program", Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Hirofumi Nohara
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan; Program for Leading Graduate Schools "HIGO (Health life science: Interdisciplinary and Glocal Oriented) Program", Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Keiko Ueno-Shuto
- Laboratory of Pharmacology, Division of Life Science, Faculty of Pharmaceutical Sciences, Sojo University, 4-22-1 Ikeda, Nishi-ku, Kumamoto 860-0082, Japan
| | - Kasumi Maruta
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Ryunosuke Nakashima
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Taisei Kawakami
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Chizuru Matsumoto
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Yuki Sakaguchi
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Tomomi Ono
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Mary Ann Suico
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Richard C Boucher
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Dieter C Gruenert
- Head and Neck Stem Cell Lab, University of California, San Francisco, 2340 Sutter St, Box 1330, N331, San Francisco, CA 94115, USA
| | - Toru Takeo
- Division of Reproductive Engineering, Center for Animal Resources and Development (CARD), Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto 860-0811, Japan
| | - Naomi Nakagata
- Division of Reproductive Engineering, Center for Animal Resources and Development (CARD), Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto 860-0811, Japan
| | - Jian-Dong Li
- Center for Inflammation, Immunity & Infection, Institute for Biomedical Sciences, Georgia State University, 714 Petit Science Center, 100 Piedmont Ave SE, Atlanta GA30303, USA
| | - Hirofumi Kai
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan.
| | - Tsuyoshi Shuto
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-ku, Kumamoto 862-0973, Japan.
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186
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Agrawal PB, Wang R, Li HL, Schmitz-Abe K, Simone-Roach C, Chen J, Shi J, Louie T, Sheng S, Towne MC, Brainson CF, Matthay MA, Kim CF, Bamshad M, Emond MJ, Gerard NP, Kleyman TR, Gerard C. The Epithelial Sodium Channel Is a Modifier of the Long-Term Nonprogressive Phenotype Associated with F508del CFTR Mutations. Am J Respir Cell Mol Biol 2017; 57:711-720. [PMID: 28708422 PMCID: PMC5765421 DOI: 10.1165/rcmb.2017-0166oc] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [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: 05/01/2017] [Accepted: 07/05/2017] [Indexed: 12/11/2022] Open
Abstract
Cystic fibrosis (CF) remains the most lethal genetic disease in the Caucasian population. However, there is great variability in clinical phenotypes and survival times, even among patients harboring the same genotype. We identified five patients with CF and a homozygous F508del mutation in the CFTR gene who were in their fifth or sixth decade of life and had shown minimal changes in lung function over a longitudinal period of more than 20 years. Because of the rarity of this long-term nonprogressive phenotype, we hypothesized these individuals may carry rare genetic variants in modifier genes that ameliorate disease severity. Individuals at the extremes of survival time and lung-function trajectory underwent whole-exome sequencing, and the sequencing data were filtered to include rare missense, stopgain, indel, and splicing variants present with a mean allele frequency of <0.2% in general population databases. Epithelial sodium channel (ENaC) mutants were generated via site-directed mutagenesis and expressed for Xenopus oocyte assays. Four of the five individuals carried extremely rare or never reported variants in the SCNN1D and SCNN1B genes of the ENaC. Separately, an independently enriched rare variant in SCNN1D was identified in the Exome Variant Server database associated with a milder pulmonary disease phenotype. Functional analysis using Xenopus oocytes revealed that two of the three variants in δ-ENaC encoded by SCNN1D exhibited hypomorphic channel activity. Our data suggest a potential role for δ-ENaC in controlling sodium reabsorption in the airways, and advance the plausibility of ENaC as a therapeutic target in CF.
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Affiliation(s)
- Pankaj B. Agrawal
- Divisions of Newborn Medicine
- Genetics and Genomics
- Gene Discovery Core, Manton Center for Orphan Disease Research
| | | | - Hongmei Lisa Li
- Stem Cell Program, Division of Hematology/Oncology, Boston Children’s Hospital, Boston, Massachusetts
- Harvard Stem Cell Institute, Cambridge, Massachusetts
- Department of Genetics, and
| | - Klaus Schmitz-Abe
- Genetics and Genomics
- Gene Discovery Core, Manton Center for Orphan Disease Research
| | | | | | - Jiahai Shi
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR
| | - Tin Louie
- Biostatistics and Center for Biomedical Statistics
| | | | - Meghan C. Towne
- Genetics and Genomics
- Gene Discovery Core, Manton Center for Orphan Disease Research
| | | | - Michael A. Matthay
- Departments of Medicine and
- Anesthesia, Cardiovascular Research Institute, University of California–San Francisco, San Francisco, California
| | - Carla F. Kim
- Pulmonary and Respiratory Diseases, and
- Stem Cell Program, Division of Hematology/Oncology, Boston Children’s Hospital, Boston, Massachusetts
- Harvard Stem Cell Institute, Cambridge, Massachusetts
- Department of Genetics, and
| | - Michael Bamshad
- Pediatrics and Genome Sciences, University of Washington, Seattle, Washington
| | | | - Norma P. Gerard
- Pulmonary and Respiratory Diseases, and
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Thomas R. Kleyman
- Departments of Medicine
- Cell Biology, and Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
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187
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Abstract
Type II nephronophthisis (NPHP2) is an autosomal recessive renal cystic disorder characterized by mutations in the inversin gene. Humans and mice with mutations in inversin have enlarged cystic kidneys that may be due to fluid accumulation resulting from altered ion transport. To address this, transepithelial ion transport was measured in shRNA-mediated inversin-depleted mouse cortical collecting duct (mCCD) cells. Loss of inversin decreased the basal ion flux in mCCD cells compared with controls. Depletion of inversin decreased vasopressin-induced Na+ absorption but did not alter Cl- secretion by mCCD cells. Addition of amiloride, a specific blocker of the epithelial sodium channel (ENaC), abolished basal ion transport in both inversin knockdown and control cells, indicating ENaC involvement. Transcript levels of ENaC β-subunit were reduced in inversin-knockdown cells consistent with decreased ENaC activity. Furthermore, Nedd4l (neural precursor cell expressed, developmentally downregulated 4 like), an upstream negative regulator of ENaC, was evaluated. The relative amount of the phosphorylated, inactive Nedd4l was decreased in inversin-depleted cells consistent with decreased ENaC activity. The protein levels of Sgk1 (serum and glucocorticoid-inducible kinase), which phosphorylates Nedd4l, remained unchanged although the transcript levels were increased in inversin-depleted cells. Interestingly, mRNA and protein levels of Crtc2 (Creb-regulated transcription coactivator) kinase, a positive regulator of Sgk1, were decreased in inversin-depleted cells. Together these results suggest that loss of inversin decreases Na+ transport via ENaC, mediated in part by transcriptional and posttranslational regulation of Crtc2/Sgk1/Nedd4l axis as a contributory mechanism for enlarged kidneys in NPHP2.
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Affiliation(s)
- Nalini H Kulkarni
- Department of Biology, Indiana University-Purdue University at Indianapolis , Indianapolis, Indiana
| | - Rosamund C Smith
- Department of Biology, Indiana University-Purdue University at Indianapolis , Indianapolis, Indiana
| | - Bonnie L Blazer-Yost
- Department of Biology, Indiana University-Purdue University at Indianapolis , Indianapolis, Indiana
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188
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Abstract
Epithelial Na+ channels (ENaCs) are members of the ENaC/degenerin family of ion channels that evolved to respond to extracellular factors. In addition to being expressed in the distal aspects of the nephron, where ENaCs couple the absorption of filtered Na+ to K+ secretion, these channels are found in other epithelia as well as nonepithelial tissues. This review addresses mechanisms by which ENaC activity is regulated by extracellular factors, including proteases, Na+, and shear stress. It also addresses other factors, including acidic phospholipids and modification of ENaC cytoplasmic cysteine residues by palmitoylation, which enhance channel activity by altering interactions of the channel with the plasma membrane.
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Affiliation(s)
- Thomas R Kleyman
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA; .,Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.,Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
| | - Ossama B Kashlan
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA; .,Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Rebecca P Hughey
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA; .,Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.,Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania 15219, USA
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189
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Martin SL, Saint-Criq V, Hwang TC, Csanády L. Ion channels as targets to treat cystic fibrosis lung disease. J Cyst Fibros 2018; 17:S22-7. [PMID: 29102290 DOI: 10.1016/j.jcf.2017.10.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/09/2017] [Accepted: 10/09/2017] [Indexed: 11/21/2022]
Abstract
Lung health relies on effective mucociliary clearance and innate immune defence mechanisms. In cystic fibrosis (CF), an imbalance in ion transport due to an absence of chloride ion secretion, caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) and a concomitant sodium hyperabsorption, caused by dyregulation of the epithelial sodium channel (ENaC), results in mucus stasis which predisposes the lungs to cycles of chronic infection and inflammation leading to lung function decline. An increased understanding of CFTR structure and function has provided opportunity for the development of a number of novel modulators targeting mutant CFTR however, it is important to also consider other ion channels and transporters present in the airways as putative targets for drug development. In this review, we discuss recent advances in CFTR biology which will contribute to further drug discovery in the field. We also examine developments to inhibit the epithelial sodium channel (ENaC) and potentially activate alternative chloride channels and transporters as a multi-tracked strategy to hydrate CF airways and restore normal mucociliary clearance mechanisms in a manner independent of CFTR mutation.
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190
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Walker MP, Cowlen M, Christensen D, Miyamoto M, Barley P, Crowder T. Nonclinical safety assessment of SPX-101, a novel peptide promoter of epithelial sodium channel internalization for the treatment of cystic fibrosis. Inhal Toxicol 2017; 29:356-365. [PMID: 28984146 DOI: 10.1080/08958378.2017.1366602] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND ENaC inhibition has long been an attractive therapeutic target for the treatment of cystic fibrosis. However, previous attempts at developing ENaC inhibitors have been unsuccessful due to complications arising from systemic circulation of the compounds. Here, we describe the preclinical toxicology assessment of a new inhaled peptide promoter of ENaC internalization delivered as a nebulized aerosol. METHODS Preclinical assessment of SPX-101 safety was determined using an in vitro hERG assay, bolus injection of SPX-101 in a canine cardiovascular and respiratory safety pharmacology model and 28-day inhalation toxicology studies of nebulized drug in rats and dogs. RESULTS SPX101 had no effects on the respiratory, cardiac or central nervous systems. The 28-day inhalation toxicology studies of nebulized SPX-101 in rats and dogs revealed no drug-related adverse events. Plasma levels of SPX-101 peaked less than 1 h after the end of treatment in rats and were below the limit of detection in canine models. CONCLUSIONS SPX-101, a novel peptide promoter of ENaC internalization, elicited no adverse effects at doses up to the MFD and in excess of the highest preclinical efficacious and expected clinical doses. In contrast to channel blockers like amiloride and derivative small molecules, SPX-101 does not achieve significant systemic circulation, thus doses are not limited due to toxic side effects like hyperkalemia and weight loss.
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Affiliation(s)
| | - Matt Cowlen
- b Cowlen Consulting, LLC , Chapel Hill , NC , USA
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191
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Al Therwani S, Malmberg MES, Rosenbaek JB, Bech JN, Pedersen EB. Effect of tolvaptan on renal handling of water and sodium, GFR and central hemodynamics in autosomal dominant polycystic kidney disease during inhibition of the nitric oxide system: a randomized, placebo-controlled, double blind, crossover study. BMC Nephrol 2017; 18:268. [PMID: 28810844 PMCID: PMC5558668 DOI: 10.1186/s12882-017-0686-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [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: 04/26/2017] [Accepted: 08/07/2017] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Tolvaptan slows progression of autosomal dominant polycystic kidney disease (ADPKD) by antagonizing the vasopressin-cAMP axis. Nitric oxide (NO) stimulates natriuresis and diuresis, but its role is unknown during tolvaptan treatment in ADPKD. METHODS Eighteen patients with ADPKD received tolvaptan 60 mg or placebo in a randomized, placebo-controlled, double blind, crossover study. L-NMMA (L-NG-monomethyl-arginine) was given as a bolus followed by continuous infusion during 60 min. We measured: GFR, urine output (UO), free water clearance (CH2O), fractional excretion of sodium (FENa), urinary excretion of aquaporin-2 channels (u-AQP2) and epithelial sodium channels (u-ENaCγ), plasma concentrations of vasopressin (p-AVP), renin (PRC), angiotensinII (p-AngII), aldosterone (p-Aldo), and central blood pressure (cBP). RESULTS During tolvaptan with NO-inhibition, a more pronounced decrease was measured in UO, CH2O (61% vs 43%) and FENa (46% vs 41%) after placebo than after tolvaptan; GFR and u-AQP2 decreased to the same extent; p-AVP increased three fold, whereas u-ENaCγ, PRC, p-AngII, and p-Aldo remained unchanged. After NO-inhibition, GFR increased after placebo and remained unchanged after tolvaptan (5% vs -6%). Central diastolic BP (CDBP) increased to a higher level after placebo than tolvaptan. Body weight fell during tolvaptan treatment. CONCLUSIONS During NO inhibition, tolvaptan antagonized both the antidiuretic and the antinatriuretic effect of L-NMMA, partly via an AVP-dependent mechanism. U-AQP2 was not changed by tolvaptan, presumeably due to a counteracting effect of elevated p-AVP. The reduced GFR during tolvaptan most likely is caused by the reduction in extracellular fluid volume and blood pressure. TRIAL REGISTRATION Clinical Trial no: NCT02527863 . Registered 18 February 2015.
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Affiliation(s)
- Safa Al Therwani
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark.
| | - My Emma Sofie Malmberg
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Jeppe Bakkestroem Rosenbaek
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Jesper Noergaard Bech
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Erling Bjerregaard Pedersen
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
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192
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Sun C, Hummler E, Hill DL. Selective Deletion of Sodium Salt Taste during Development Leads to Expanded Terminal Fields of Gustatory Nerves in the Adult Mouse Nucleus of the Solitary Tract. J Neurosci 2017; 37:660-72. [PMID: 28100747 DOI: 10.1523/JNEUROSCI.2913-16.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 11/04/2016] [Accepted: 12/01/2016] [Indexed: 11/21/2022] Open
Abstract
Neuronal activity plays a key role in the development of sensory circuits in the mammalian brain. In the gustatory system, experimental manipulations now exist, through genetic manipulations of specific taste transduction processes, to examine how specific taste qualities (i.e., basic tastes) impact the functional and structural development of gustatory circuits. Here, we used a mouse knock-out model in which the transduction component used to discriminate sodium salts from other taste stimuli was deleted in taste bud cells throughout development. We used this model to test the hypothesis that the lack of activity elicited by sodium salt taste impacts the terminal field organization of nerves that carry taste information from taste buds to the nucleus of the solitary tract (NST) in the medulla. The glossopharyngeal, chorda tympani, and greater superficial petrosal nerves were labeled to examine their terminal fields in adult control mice and in adult mice in which the α-subunit of the epithelial sodium channel was conditionally deleted in taste buds (αENaC knockout). The terminal fields of all three nerves in the NST were up to 2.7 times greater in αENaC knock-out mice compared with the respective field volumes in control mice. The shapes of the fields were similar between the two groups; however, the density and spread of labels were greater in αENaC knock-out mice. Overall, our results show that disruption of the afferent taste signal to sodium salts disrupts the normal age-dependent "pruning" of all terminal fields, which could lead to alterations in sensory coding and taste-related behaviors. SIGNIFICANCE STATEMENT Neural activity plays a major role in the development of sensory circuits in the mammalian brain. To date, there has been no direct test of whether taste-elicited neural activity has a role in shaping central gustatory circuits. However, recently developed genetic tools now allow an assessment of how specific taste stimuli, in this case sodium salt taste, play a role in the maturation of the terminal fields in the mouse brainstem. We found that the specific deletion of sodium salt taste during development produced terminal fields in adults that were dramatically larger than in control mice, demonstrating for the first time that sodium salt taste-elicited activity is necessary for the normal maturation of gustatory inputs into the brain.
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193
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Krenn K, Lucas R, Croizé A, Boehme S, Klein KU, Hermann R, Markstaller K, Ullrich R. Inhaled AP301 for treatment of pulmonary edema in mechanically ventilated patients with acute respiratory distress syndrome: a phase IIa randomized placebo-controlled trial. Crit Care 2017; 21:194. [PMID: 28750677 PMCID: PMC5531100 DOI: 10.1186/s13054-017-1795-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 07/12/2017] [Indexed: 02/08/2023]
Abstract
Background High-permeability pulmonary edema is a hallmark of acute respiratory distress syndrome (ARDS) and is frequently accompanied by impaired alveolar fluid clearance (AFC). AP301 enhances AFC by activating epithelial sodium channels (ENaCs) on alveolar epithelial cells, and we investigated its effect on extravascular lung water index (EVLWI) in mechanically ventilated patients with ARDS. Methods Forty adult mechanically ventilated patients with ARDS were included in a randomized, double-blind, placebo-controlled trial for proof of concept. Patients were treated with inhaled AP301 (n = 20) or placebo (0.9% NaCl; n = 20) twice daily for 7 days. EVLWI was measured by thermodilution (PiCCO®), and treatment groups were compared using the nonparametric Mann–Whitney U test. Results AP301 inhalation was well tolerated. No differences in mean baseline-adjusted change in EVLWI from screening to day 7 were found between the AP301 and placebo group (p = 0.196). There was no difference in the PaO2/FiO2 ratio, ventilation pressures, Murray lung injury score, or 28-day mortality between the treatment groups. An exploratory subgroup analysis according to severity of illness showed reductions in EVLWI (p = 0.04) and ventilation pressures (p < 0.05) over 7 days in patients with initial sequential organ failure assessment (SOFA) scores ≥11 inhaling AP301 versus placebo, but not in patients with SOFA scores ≤10. Conclusions There was no difference in mean baseline-adjusted EVLWI between the AP301 and placebo group. An exploratory post-hoc subgroup analysis indicated reduced EVLWI in patients with SOFA scores ≥11 receiving AP301. These results suggest further confirmation in future clinical trials of inhaled AP301 for treatment of pulmonary edema in patients with ARDS. Trial registration The study was prospectively registered at clinicaltrials.gov, NCT01627613. Registered 20 June 2012. Electronic supplementary material The online version of this article (doi:10.1186/s13054-017-1795-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Katharina Krenn
- Department of Anaesthesia, Critical Care and Pain Medicine, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria
| | - Rudolf Lucas
- Vascular Biology Center, Department of Pharmacology and Toxicology and Division of Pulmonary and Critical Care Medicine, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Adrien Croizé
- Department of Anaesthesia, Critical Care and Pain Medicine, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria
| | - Stefan Boehme
- Department of Anaesthesia, Critical Care and Pain Medicine, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria
| | - Klaus Ulrich Klein
- Department of Anaesthesia, Critical Care and Pain Medicine, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria
| | | | - Klaus Markstaller
- Department of Anaesthesia, Critical Care and Pain Medicine, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria
| | - Roman Ullrich
- Department of Anaesthesia, Critical Care and Pain Medicine, Medical University of Vienna, Waehringer Guertel 18-20, A-1090, Vienna, Austria.
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Nagarajan S, Vohra T, Loffing J, Faresse N. Protein Phosphatase 1α enhances renal aldosterone signaling via mineralocorticoid receptor stabilization. Mol Cell Endocrinol 2017; 450:74-82. [PMID: 28454724 DOI: 10.1016/j.mce.2017.04.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 04/18/2017] [Accepted: 04/22/2017] [Indexed: 01/21/2023]
Abstract
Stimulation of the mineralocorticoid receptor (MR) by aldosterone controls several physiological parameters including blood pressure, inflammation or metabolism. We previously showed that MR turnover constitutes a crucial regulatory step in the responses of renal epithelial cells to aldosterone. Here, we identified Protein Phosphatase 1 alpha (PP1α), as a novel cytoplasmic binding partner of MR that promotes the receptor activity. The RT-PCR expression mapping of PP1α reveals a high expression in the kidney, particularly in the distal part of the nephron. At the molecular level, we demonstrate that PP1α inhibits the ubiquitin ligase Mdm2 by dephosphorylation, preventing its interaction with MR. This results in the accumulation of the receptor due to reduction of its proteasomal degradation and consequently a greater aldosterone-induced Na+ uptake by renal cells. Thus, our findings describe an original mechanism involving a phosphatase in the regulation of aldosterone signaling and provide new and important insights into the molecular mechanism underlying the MR turnover.
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Affiliation(s)
- Shunmugam Nagarajan
- Institute of Anatomy, University of Zurich, 8057 Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Switzerland
| | - Twinkle Vohra
- Institute of Anatomy, University of Zurich, 8057 Zurich, Switzerland
| | - Johannes Loffing
- Institute of Anatomy, University of Zurich, 8057 Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Switzerland
| | - Nourdine Faresse
- Institute of Anatomy, University of Zurich, 8057 Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Switzerland.
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195
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Salih M, Gautschi I, van Bemmelen MX, Di Benedetto M, Brooks AS, Lugtenberg D, Schild L, Hoorn EJ. A Missense Mutation in the Extracellular Domain of αENaC Causes Liddle Syndrome. J Am Soc Nephrol 2017; 28:3291-3299. [PMID: 28710092 DOI: 10.1681/asn.2016111163] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [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: 11/02/2016] [Accepted: 06/04/2017] [Indexed: 11/03/2022] Open
Abstract
Liddle syndrome is an autosomal dominant form of hypokalemic hypertension due to mutations in the β- or γ-subunit of the epithelial sodium channel (ENaC). Here, we describe a family with Liddle syndrome due to a mutation in αENaC. The proband was referred because of resistant hypokalemic hypertension, suppressed renin and aldosterone, and no mutations in the genes encoding β- or γENaC. Exome sequencing revealed a heterozygous, nonconservative T>C single-nucleotide mutation in αENaC that substituted Cys479 with Arg (C479R). C479 is a highly conserved residue in the extracellular domain of ENaC and likely involved in a disulfide bridge with the partner cysteine C394. In oocytes, the C479R and C394S mutations resulted in similar twofold increases in amiloride-sensitive ENaC current. Quantification of mature cleaved αENaC in membrane fractions showed that the number of channels did not increase with these mutations. Trypsin, which increases open probability of the channel by proteolytic cleavage, resulted in significantly higher currents in the wild type than in C479R or C394S mutants. In summary, a mutation in the extracellular domain of αENaC causes Liddle syndrome by increasing intrinsic channel activity. This mechanism differs from that of the β- and γ-mutations, which result in an increase in channel density at the cell surface. This mutation may explain other cases of patients with resistant hypertension and also provides novel insight into ENaC activation, which is relevant for kidney sodium reabsorption and salt-sensitive hypertension.
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Affiliation(s)
| | - Ivan Gautschi
- Département de Pharmacologie et de Toxicologie, Université de Lausanne, Lausanne, Switzerland; and
| | - Miguel X van Bemmelen
- Département de Pharmacologie et de Toxicologie, Université de Lausanne, Lausanne, Switzerland; and
| | - Michael Di Benedetto
- Département de Pharmacologie et de Toxicologie, Université de Lausanne, Lausanne, Switzerland; and
| | - Alice S Brooks
- Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Dorien Lugtenberg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Laurent Schild
- Département de Pharmacologie et de Toxicologie, Université de Lausanne, Lausanne, Switzerland; and
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196
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Abstract
The importance of renal ammonia metabolism in acid-base homeostasis is well known. However, the effects of renal ammonia metabolism other than in acid-base homeostasis are not as widely recognized. First, ammonia differs from almost all other solutes in the urine in that it does not result from arterial delivery. Instead, ammonia is produced by the kidney, and only a portion of the ammonia produced is excreted in the urine, with the remainder returned to the systemic circulation through the renal veins. In normal individuals, systemic ammonia addition is metabolized efficiently by the liver, but in patients with either acute or chronic liver disease, conditions that increase the addition of ammonia of renal origin to the systemic circulation can result in precipitation and/or worsening of hyperammonemia. Second, ammonia appears to serve as an intrarenal paracrine signaling molecule. Hypokalemia increases proximal tubule ammonia production and secretion as well as reabsorption in the thick ascending limb of the loop of Henle, thereby increasing delivery to the renal interstitium and the collecting duct. In the collecting duct, ammonia decreases potassium secretion and stimulates potassium reabsorption, thereby decreasing urinary potassium excretion and enabling feedback correction of the initiating hypokalemia. Finally, the stimulation of renal ammonia metabolism by hypokalemia may contribute to the development of metabolic alkalosis, which in turn can stimulate NaCl reabsorption and contribute to the intravascular volume expansion, increased blood pressure and diuretic resistance that can develop with hypokalemia. The evidence supporting these novel non-acid-base roles of renal ammonia metabolism is discussed in this review.
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Affiliation(s)
- I. David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College Of Medicine, Gainesville Florida,Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville Florida
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197
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Crosby JR, Zhao C, Jiang C, Bai D, Katz M, Greenlee S, Kawabe H, McCaleb M, Rotin D, Guo S, Monia BP. Inhaled ENaC antisense oligonucleotide ameliorates cystic fibrosis-like lung disease in mice. J Cyst Fibros 2017; 16:671-680. [PMID: 28539224 DOI: 10.1016/j.jcf.2017.05.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 04/26/2017] [Accepted: 05/08/2017] [Indexed: 01/19/2023]
Abstract
BACKGROUND Epithelial sodium channel (ENaC, Scnn1) hyperactivity in the lung leads to airway surface dehydration and mucus accumulation in cystic fibrosis (CF) patients and in mice with CF-like lung disease. METHODS We identified several potent ENaC specific antisense oligonucleotides (ASOs) and tested them by inhalation in mouse models of CF-like lung disease. RESULTS The inhaled ASOs distributed into lung airway epithelial cells and decreased ENaC expression by inducing RNase H1-dependent degradation of the targeted Scnn1a mRNA. Aerosol delivered ENaC ASO down-regulated mucus marker expression and ameliorated goblet cell metaplasia, inflammation, and airway hyper-responsiveness. Lack of systemic activity of ASOs delivered via the aerosol route ensures the safety of this approach. CONCLUSIONS Our results demonstrate that antisense inhibition of ENaC in airway epithelial cells could be an effective and safe approach for the prevention and reversal of lung symptoms in CF and potentially other inflammatory diseases of the lung.
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Affiliation(s)
- Jeff R Crosby
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA.
| | - Chenguang Zhao
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Chong Jiang
- The Hospital for Sick Children, 686 Bay Street, Toronto, Ontario M5G 0A4, Canada
| | - Dong Bai
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Melanie Katz
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Sarah Greenlee
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Hiroshi Kawabe
- Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Michael McCaleb
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Daniela Rotin
- The Hospital for Sick Children, 686 Bay Street, Toronto, Ontario M5G 0A4, Canada
| | - Shuling Guo
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Brett P Monia
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
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198
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Pavlov TS, Levchenko V, Ilatovskaya DV, Li H, Palygin O, Pastor-Soler NM, Hallows KR, Staruschenko A. Lack of Effects of Metformin and AICAR Chronic Infusion on the Development of Hypertension in Dahl Salt-Sensitive Rats. Front Physiol 2017; 8:227. [PMID: 28473772 PMCID: PMC5397526 DOI: 10.3389/fphys.2017.00227] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 03/31/2017] [Indexed: 12/19/2022] Open
Abstract
In the kidney, reabsorption via the epithelial sodium channel (ENaC) is involved in long-term blood pressure control. Previously we demonstrated that ENaC hyperactivity is associated with development of salt-sensitive (SS) hypertension in Dahl SS rats. AMP-activated kinase (AMPK), playing a role in cellular energy homeostasis, has been shown to decrease ENaC activity. Here, we tested whether metformin and AICAR, two drugs that activate AMPK, affect the development of salt-induced hypertension. High salt diet significantly increased mean arterial pressure (MAP) in Dahl SS rats. Blood pressure elevation was accompanied by a short-term decline of heart rate and increased circadian arterial pressure dipping. Metformin and AICAR were delivered intravenously at doses of 200 and 20 mg/kg/day, respectively. However, both control and drug-treated groups had similar development of high blood pressure within 3 weeks of 8% NaCl dietary salt intake. In the metformin-treated animals MAP reached 164.9 ± 9.1 mmHg, which was not significantly different from the control group (171.8 ± 5.6 mmHg). Patch clamp analysis revealed that the metformin-treated rats had no difference in the activity of ENaC. AICAR treatment also did not affect the development of hypertension and kidney injury. MAP reached 182.8 ± 4.8 and 178.0 ± 2.8 mmHg in AICAR and vehicle treated groups, respectively. Of note, we found that high-salt diet activated AMPK in the Dahl SS rats, and treatment with these AMPK activators had no significant further effect on AMPK activity. We conclude that AMPK activators, at least under these conditions, do not affect development of hypertension during high-salt diet in the Dahl SS rat model.
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Affiliation(s)
- Tengis S Pavlov
- Department of Physiology, Medical College of WisconsinMilwaukee, WI, USA.,Division of Hypertension and Vascular Research, Henry Ford HospitalDetroit, MI, USA
| | | | | | - Hui Li
- Division of Nephrology and Hypertension, Department of Medicine, Keck School of Medicine, University of Southern California, Los AngelesLos Angeles, CA, USA
| | - Oleg Palygin
- Department of Physiology, Medical College of WisconsinMilwaukee, WI, USA
| | - Nuria M Pastor-Soler
- Division of Nephrology and Hypertension, Department of Medicine, Keck School of Medicine, University of Southern California, Los AngelesLos Angeles, CA, USA
| | - Kenneth R Hallows
- Division of Nephrology and Hypertension, Department of Medicine, Keck School of Medicine, University of Southern California, Los AngelesLos Angeles, CA, USA
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199
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Sasamoto K, Marunaka R, Niisato N, Sun H, Taruno A, Pezzotti G, Yamamoto T, Kanamura N, Zhu W, Nishio K, Inui T, Eaton DC, Marunaka Y. Analysis of Aprotinin, a Protease Inhibitor, Action on the Trafficking of Epithelial Na+ Channels ( ENaC) in Renal Epithelial Cells Using a Mathematical Model. Cell Physiol Biochem 2017; 41:1865-1880. [PMID: 28478438 DOI: 10.1159/000471934] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [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: 11/15/2016] [Accepted: 01/25/2017] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIM Epithelial Na+ channels (ENaC) play a crucial role in control of blood pressure by regulating renal Na+ reabsorption. Intracellular trafficking of ENaC is one of the key regulators of ENaC function, but a quantitative description of intracellular recycling of endogenously expressed ENaC is unavailable. We attempt here to provide a model for intracellular recycling after applying a protease inhibitor under hypotonic conditions. METHODS We simulated the ENaC-mediated Na+ transport in renal epithelial A6 cells measured as short-circuit currents using a four-state mathematical ENaC trafficking model. RESULTS We developed a four-state mathematical model of ENaC trafficking in the cytosol of renal epithelial cells that consists of: an insertion state of ENaC that can be trafficked to the apical membrane state (insertion rate); an apical membrane state of ENaC conducting Na+ across the apical membrane; a recycling state containing ENaC that are retrieved from the apical membrane state (endocytotic rate) and then to the insertion state (recycling rate) communicating with the apical membrane state or to a degradation state (degradation rate). We studied the effect of aprotinin (a protease inhibitor) blocking protease-induced cleavage of the extracellular loop of γ ENaC subunit on the rates of intracellular ENaC trafficking using the above-defined four-state mathematical model of ENaC trafficking and the recycling number relative to ENaC staying in the apical membrane. We found that aprotinin significantly reduced the insertion rate of ENaC to the apical membrane by 40%, the recycling rate of ENaC by 81%, the cumulative time of an individual ENaC staying in the apical membrane by 32%, the cumulative life-time after the first endocytosis of ENaC by 25%, and the cumulative Na+ absorption by 31%. The most interesting result of the present study is that cleavage of ENaC affects the intracellular ENaC trafficking rate and determines the residency time of ENaC, indicating that more active cleaved ENaCs stay longer at the apical membrane contributing to transcellular Na+ transport via an increase in recycling of ENaC to the apical membrane. CONCLUSION The extracellular protease-induced cleavage of the extracellular loop of γ ENaC subunit increases transcellular epithelial Na+ transport by elevating the recycling rate of ENaC due to an increase in the recycling rate of ENaCs associated with increases in the insertion rate of ENaC.
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Affiliation(s)
| | - Rie Marunaka
- Department of Molecular Cell Physiology, Kyoto, Japan.,Department of Dental Medicine, Kyoto, Japan
| | - Naomi Niisato
- Department of Molecular Cell Physiology, Kyoto, Japan.,Department of Health and Sports Sciences, Faculty of Health and Medical Sciences, Kyoto Gakuen University, Kameoka, Japan.,Japan Institute for Food Education and Health, St. Agnes' University, Kyoto, Japan
| | - Hongxin Sun
- Department of Molecular Cell Physiology, Kyoto, Japan
| | | | - Giuseppe Pezzotti
- Department of Molecular Cell Physiology, Kyoto, Japan.,Ceramic Physics Laboratory, Kyoto Institute of Technology, Kyoto, Japan
| | | | | | - Wenliang Zhu
- Department of Medical Engineering for Treatment of Bone and Joint Disorders, Osaka University, Suita, Japan
| | - Kyosuke Nishio
- Department of Molecular Cell Physiology, Kyoto, Japan.,Japan Institute for Food Education and Health, St. Agnes' University, Kyoto, Japan.,Shin-Koiwa Clinic, Tokyo, Japan
| | - Toshio Inui
- Department of Molecular Cell Physiology, Kyoto, Japan.,Department of Bio-Ionomics, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan.,Saisei Mirai Clinics, Moriguchi, Japan
| | - Douglas C Eaton
- Center for Cell & Molecular Signaling, Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Yoshinori Marunaka
- Department of Molecular Cell Physiology, Kyoto, Japan.,Department of Bio-Ionomics, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan.,Japan Institute for Food Education and Health, St. Agnes' University, Kyoto, Japan
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200
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McDonough AA, Veiras LC, Guevara CA, Ralph DL. Cardiovascular benefits associated with higher dietary K + vs. lower dietary Na +: evidence from population and mechanistic studies. Am J Physiol Endocrinol Metab 2017; 312:E348-E356. [PMID: 28174181 PMCID: PMC5406991 DOI: 10.1152/ajpendo.00453.2016] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 01/26/2017] [Accepted: 02/03/2017] [Indexed: 12/24/2022]
Abstract
The World Health Organization ranks hypertension the leading global risk factor for disease, specifically, cardiovascular disease. Blood pressure (BP) is higher in Westernized populations consuming Na+-rich processed foods than in isolated societies consuming K+-rich natural foods. Evidence suggests that lowering dietary Na+ is particularly beneficial in hypertensive individuals who consume a high-Na+ diet. Nonetheless, numerous population studies demonstrate a relationship between higher dietary K+, estimated from urinary excretion or dietary recall, and lower BP, regardless of Na+ intake. Interventional studies with K+ supplementation suggest that it provides a direct benefit; K+ may also be a marker for other beneficial components of a "natural" diet. Recent studies in rodent models indicate mechanisms for the K+ benefit: the distal tubule Na+-Cl- cotransporter (NCC) controls Na+ delivery downstream to the collecting duct, where Na+ reabsorbed by epithelial Na+ channels drives K+ secretion and excretion through K+ channels in the same region. High dietary K+ provokes a decrease in NCC activity to drive more K+ secretion (and Na+ excretion, analogous to the actions of a thiazide diuretic) whether Na+ intake is high or low; low dietary K+ provokes an increase in NCC activity and Na+ retention, also independent of dietary Na+ Together, the findings suggest that public health efforts directed toward increasing consumption of K+-rich natural foods would reduce BP and, thus, cardiovascular and kidney disease.
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Affiliation(s)
- Alicia A McDonough
- Department of Cell and Neurobiology, Keck School of Medicine of the University of Southern California, Los Angeles, California
| | - Luciana C Veiras
- Department of Cell and Neurobiology, Keck School of Medicine of the University of Southern California, Los Angeles, California
| | - Claire A Guevara
- Department of Cell and Neurobiology, Keck School of Medicine of the University of Southern California, Los Angeles, California
| | - Donna L Ralph
- Department of Cell and Neurobiology, Keck School of Medicine of the University of Southern California, Los Angeles, California
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