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Elevated intracellular Na + and osmolarity stimulate catalytic activity of the ubiquitin ligase Nedd4-2. Proc Natl Acad Sci U S A 2022; 119:e2122495119. [PMID: 35858421 PMCID: PMC9335340 DOI: 10.1073/pnas.2122495119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Regulation of catalytic activity of E3 ubiquitin ligases is critical for their cellular functions. We identified an unexpected mode of regulation of E3 catalytic activity by ions and osmolarity; enzymatic activity of the HECT family E3 Nedd4-2/Nedd4L is enhanced by increased intracellular Na+ ([Na+]i) and by hyperosmolarity. This stimulated activity is mediated by activation of p38-MAPK and is inhibited by WNKs. Moreover, protease (Furin)-mediated activation of the epithelial Na+ channel ENaC (a bona fide Nedd4-2 substrate), which leads to increased [Na+]i and osmolarity, results in enhanced Nedd4-2 catalytic activity. This enhancement is inhibited by a Furin inhibitor, by a protease-resistant ENaC mutant, or by treatment with the ENaC inhibitor amiloride. Moreover, WNK inhibition, which stimulates catalytic activity of Nedd4-2, leads to reduced levels of cell-surface ENaC and reduced channel activity. ENaC activity does not affect Nedd4-2:ENaC binding. Therefore, these results demonstrate activation of a ubiquitin ligase by Na+ and osmotic changes. Importantly, they reveal a negative feedback loop in which active ENaC leads to stimulation of catalytic activity of its own suppressor, Nedd4-2, to protect cells from excessive Na+ loading and hyperosmotic stress and to protect the animal from hypertension.
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McMullan CJ, McHill AW, Hull JT, Wang W, Forman JP, Klerman EB. Sleep Restriction and Recurrent Circadian Disruption Differentially Affects Blood Pressure, Sodium Retention, and Aldosterone Secretion. Front Physiol 2022; 13:914497. [PMID: 35874530 PMCID: PMC9305384 DOI: 10.3389/fphys.2022.914497] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/03/2022] [Indexed: 12/14/2022] Open
Abstract
Prolonged exposure to chronic sleep restriction (CSR) and shiftwork are both associated with incident hypertension and cardiovascular disease. We hypothesized that the combination of CSR and shiftwork's rotating sleep schedule (causing recurrent circadian disruption, RCD) would increase blood pressure, renal sodium retention, potassium excretion, and aldosterone excretion. Seventeen healthy participants were studied during a 32-day inpatient protocol that included 20-h "days" with associated scheduled sleep/wake and eating behaviors. Participants were randomly assigned to restricted (1:3.3 sleep:wake, CSR group) or standard (1:2 sleep:wake, Control group) ratios of sleep:wake duration. Systolic blood pressure during circadian misalignment was ∼6% higher in CSR conditions. Renal sodium and potassium excretion showed robust circadian patterns; potassium excretion also displayed some influence of the scheduled behaviors (sleep/wake, fasting during sleep so made parallel fasting/feeding). In contrast, the timing of renal aldosterone excretion was affected predominately by scheduled behaviors. Per 20-h "day," total sodium excretion increased, and total potassium excretion decreased during RCD without a change in total aldosterone excretion. Lastly, a reduced total renal sodium excretion was found despite constant oral sodium consumption and total aldosterone excretion, suggesting a positive total body sodium balance independent of aldosterone excretion. These findings may provide mechanistic insight into the observed adverse cardiovascular and renal effects of shiftwork.
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Affiliation(s)
- Ciaran J. McMullan
- Renal Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, United States,Channing Division of Network Medicine, Brigham and Women’s Hospital, Boston, MA, United States
| | - Andrew W. McHill
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital, Boston, MA, United States,Division of Sleep Medicine, Harvard Medical School, Boston, MA, United States,Sleep, Chronobiology, and Health Laboratory, School of Nursing, Oregon Health & Science University, Portland, OR, United States,*Correspondence: Andrew W. McHill,
| | - Joseph T. Hull
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital, Boston, MA, United States,Division of Sleep Medicine, Harvard Medical School, Boston, MA, United States
| | - Wei Wang
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital, Boston, MA, United States,Division of Sleep Medicine, Harvard Medical School, Boston, MA, United States
| | - John P. Forman
- Renal Division, Department of Medicine, Brigham and Women’s Hospital, Boston, MA, United States,Channing Division of Network Medicine, Brigham and Women’s Hospital, Boston, MA, United States
| | - Elizabeth B. Klerman
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital, Boston, MA, United States,Division of Sleep Medicine, Harvard Medical School, Boston, MA, United States,Department of Neurology, Massachusetts General Hospital, Boston, MA, United States
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53
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Kaulich E, Carroll T, Ackley B, Tang YQ, Hardege I, Nehrke K, Schafer WR, Walker DS. Distinct roles for two Caenorhabditis elegans acid-sensing ion channels in an ultradian clock. eLife 2022; 11:75837. [PMID: 35666106 PMCID: PMC9374441 DOI: 10.7554/elife.75837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 06/01/2022] [Indexed: 11/13/2022] Open
Abstract
Biological clocks are fundamental to an organism's health, controlling periodicity of behaviour and metabolism. Here, we identify two acid-sensing ion channels, with very different proton sensing properties, and describe their role in an ultradian clock, the defecation motor program (DMP) of the nematode Caenorhabditis elegans. An ACD-5-containing channel, on the apical membrane of the intestinal epithelium, is essential for maintenance of luminal acidity, and thus the rhythmic oscillations in lumen pH. In contrast, the second channel, composed of FLR-1, ACD-3 and/or DEL-5, located on the basolateral membrane, controls the intracellular Ca2+ wave and forms a core component of the master oscillator that controls timing and rhythmicity of the DMP. flr-1 and acd-3/del-5 mutants show severe developmental and metabolic defects. We thus directly link the proton-sensing properties of these channels to their physiological roles in pH regulation and Ca2+ signalling, the generation of an ultradian oscillator, and its metabolic consequences.
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Affiliation(s)
- Eva Kaulich
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Trae Carroll
- Department of Pathology and Lab Medicine, University of Rochester, Rochester, United States
| | - Brian Ackley
- Department of Molecular Biosciences, University of Kansas, Lawrence, United States
| | - Yi-Quan Tang
- Institutes of Brain Science, Fudan University, Shanghai, China
| | - Iris Hardege
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Keith Nehrke
- Department of Medicine, University of Rochester, Rochester, United States
| | - William R Schafer
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Denise S Walker
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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54
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Brown EF, Mitaera T, Fronius M. COVID-19 and Liquid Homeostasis in the Lung—A Perspective through the Epithelial Sodium Channel (ENaC) Lens. Cells 2022; 11:cells11111801. [PMID: 35681496 PMCID: PMC9180030 DOI: 10.3390/cells11111801] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 05/23/2022] [Accepted: 05/25/2022] [Indexed: 01/26/2023] Open
Abstract
Infections with a new corona virus in 2019 lead to the definition of a new disease known as Corona Virus Disease 2019 (COVID-19). The sever cases of COVID-19 and the main cause of death due to virus infection are attributed to respiratory distress. This is associated with the formation of pulmonary oedema that impairs blood oxygenation and hypoxemia as main symptoms of respiratory distress. An important player for the maintenance of a defined liquid environment in lungs needed for normal lung function is the epithelial sodium channel (ENaC). The present article reviews the implications of SARS-CoV-2 infections from the perspective of impaired function of ENaC. The rationale for this perspective is derived from the recognition that viral spike protein and ENaC share a common proteolytic cleavage site. This cleavage site is utilized by the protease furin, that is essential for ENaC activity. Furin cleavage of spike ‘activates’ the virus protein to enable binding to host cell membrane receptors and initiate cell infection. Based on the importance of proteolytic cleavage for ENaC function and activation of spike, it seems feasible to assume that virus infections are associated with impaired ENaC activity. This is further supported by symptoms of COVID-19 that are reminiscent of impaired ENaC function in the respiratory tract.
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Affiliation(s)
- Emily F. Brown
- Department of Physiology, University of Otago, Dunedin 9054, New Zealand; (E.F.B.); (T.M.)
- HeartOtago, University of Otago, Dunedin, New Zealand
| | - Tamapuretu Mitaera
- Department of Physiology, University of Otago, Dunedin 9054, New Zealand; (E.F.B.); (T.M.)
- HeartOtago, University of Otago, Dunedin, New Zealand
| | - Martin Fronius
- Department of Physiology, University of Otago, Dunedin 9054, New Zealand; (E.F.B.); (T.M.)
- HeartOtago, University of Otago, Dunedin, New Zealand
- Healthy Hearts for Aotearoa New Zealand, Centre of Research Excellence, New Zealand
- Maurice Wilkins Centre for Molecular Discovery, Centre of Research Excellence, New Zealand
- Correspondence: ; Tel.: +64-3-471-6081
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Mernea M, Ulăreanu RȘ, Cucu D, Al-Saedi JH, Pop CE, Fendrihan S, Anghelescu GDC, Mihăilescu DF. Epithelial Sodium Channel Inhibition by Amiloride Addressed with THz Spectroscopy and Molecular Modeling. Molecules 2022; 27:3271. [PMID: 35630748 PMCID: PMC9144217 DOI: 10.3390/molecules27103271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 05/08/2022] [Accepted: 05/18/2022] [Indexed: 11/16/2022] Open
Abstract
THz spectroscopy is important for the study of ion channels because it directly addresses the low frequency collective motions relevant for their function. Here we used THz spectroscopy to investigate the inhibition of the epithelial sodium channel (ENaC) by its specific blocker, amiloride. Experiments were performed on A6 cells' suspensions, which are cells overexpressing ENaC derived from Xenopus laevis kidney. THz spectra were investigated with or without amiloride. When ENaC was inhibited by amiloride, a substantial increase in THz absorption was noticed. Molecular modeling methods were used to explain the observed spectroscopic differences. THz spectra were simulated using the structural models of ENaC and ENaC-amiloride complexes built here. The agreement between the experiment and the simulations allowed us to validate the structural models and to describe the amiloride dynamics inside the channel pore. The amiloride binding site validated using THz spectroscopy agrees with previous mutagenesis studies. Altogether, our results show that THz spectroscopy can be successfully used to discriminate between native and inhibited ENaC channels and to characterize the dynamics of channels in the presence of their specific antagonist.
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Affiliation(s)
- Maria Mernea
- Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, 91–95 Splaiul Independenței Str., 050095 Bucharest, Romania; (M.M.); (R.Ș.U.); (J.H.A.-S.); (G.D.C.A.); (D.F.M.)
| | - Roxana Ștefania Ulăreanu
- Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, 91–95 Splaiul Independenței Str., 050095 Bucharest, Romania; (M.M.); (R.Ș.U.); (J.H.A.-S.); (G.D.C.A.); (D.F.M.)
| | - Dana Cucu
- Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, 91–95 Splaiul Independenței Str., 050095 Bucharest, Romania; (M.M.); (R.Ș.U.); (J.H.A.-S.); (G.D.C.A.); (D.F.M.)
| | - Jasim Hafedh Al-Saedi
- Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, 91–95 Splaiul Independenței Str., 050095 Bucharest, Romania; (M.M.); (R.Ș.U.); (J.H.A.-S.); (G.D.C.A.); (D.F.M.)
| | - Cristian-Emilian Pop
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, 91–95 Splaiul Independenței Str., 050095 Bucharest, Romania;
- Non-Governmental Research Organization Biologic, 14 Schitului Str., 032044 Bucharest, Romania;
| | - Sergiu Fendrihan
- Non-Governmental Research Organization Biologic, 14 Schitului Str., 032044 Bucharest, Romania;
- Faculty of Medicine, University “Vasile Goldis”, Bulevardul Revoluției 94, 310025 Arad, Romania
| | - Giorgiana Diana Carmen Anghelescu
- Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, 91–95 Splaiul Independenței Str., 050095 Bucharest, Romania; (M.M.); (R.Ș.U.); (J.H.A.-S.); (G.D.C.A.); (D.F.M.)
| | - Dan Florin Mihăilescu
- Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, 91–95 Splaiul Independenței Str., 050095 Bucharest, Romania; (M.M.); (R.Ș.U.); (J.H.A.-S.); (G.D.C.A.); (D.F.M.)
- Biometric Psychiatric Genetics Research Unit, Alexandru Obregia Psychiatric Hospital, 10 Șoseaua Berceni Str., 041914 Bucharest, Romania
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56
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Diakov A, Nesterov V, Dahlmann A, Korbmacher C. Two adjacent phosphorylation sites in the C-terminus of the channel's α-subunit have opposing effects on epithelial sodium channel (ENaC) activity. Pflugers Arch 2022; 474:681-697. [PMID: 35525869 PMCID: PMC9192390 DOI: 10.1007/s00424-022-02693-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 04/25/2022] [Indexed: 02/07/2023]
Abstract
How phosphorylation of the epithelial sodium channel (ENaC) contributes to its regulation is incompletely understood. Previously, we demonstrated that in outside-out patches ENaC activation by serum- and glucocorticoid-inducible kinase isoform 1 (SGK1) was abolished by mutating a serine residue in a putative SGK1 consensus motif RXRXX(S/T) in the channel’s α-subunit (S621 in rat). Interestingly, this serine residue is followed by a highly conserved proline residue rather than by a hydrophobic amino acid thought to be required for a functional SGK1 consensus motif according to invitro data. This suggests that this serine residue is a potential phosphorylation site for the dual-specificity tyrosine phosphorylated and regulated kinase 2 (DYRK2), a prototypical proline-directed kinase. Its phosphorylation may prime a highly conserved preceding serine residue (S617 in rat) to be phosphorylated by glycogen synthase kinase 3 β (GSK3β). Therefore, we investigated the effect of DYRK2 on ENaC activity in outside-out patches of Xenopus laevis oocytes heterologously expressing rat ENaC. DYRK2 included in the pipette solution significantly increased ENaC activity. In contrast, GSK3β had an inhibitory effect. Replacing S621 in αENaC with alanine (S621A) abolished the effects of both kinases. A S617A mutation reduced the inhibitory effect of GKS3β but did not prevent ENaC activation by DYRK2. Our findings suggest that phosphorylation of S621 activates ENaC and primes S617 for subsequent phosphorylation by GSK3β resulting in channel inhibition. In proof-of-concept experiments, we demonstrated that DYRK2 can also stimulate ENaC currents in microdissected mouse distal nephron, whereas GSK3β inhibits the currents.
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Affiliation(s)
- Alexei Diakov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstr, 6, 91054, Erlangen, Germany
| | - Viatcheslav Nesterov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstr, 6, 91054, Erlangen, Germany
| | - Anke Dahlmann
- Medizinische Klinik 4 - Nephrologie und Hypertensiologie, Universitätsklinikum Erlangen, Ulmenweg 18, 91054, Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstr, 6, 91054, Erlangen, Germany.
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Epithelial Sodium Channel Alpha Subunit (αENaC) Is Associated with Inverse Salt Sensitivity of Blood Pressure. Biomedicines 2022; 10:biomedicines10050981. [PMID: 35625718 PMCID: PMC9138231 DOI: 10.3390/biomedicines10050981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 04/20/2022] [Accepted: 04/20/2022] [Indexed: 01/07/2023] Open
Abstract
Salt sensitivity of blood pressure (BP) refers to an increase in BP following an increase in dietary salt, which is associated with increased incidence of cardiovascular disease and early death. However, decreased sodium intake also increases mortality and morbidity. Inverse salt sensitivity (ISS), defined as a paradoxical increase in BP on a low-salt diet, about 11% of the population, may be the cause of this phenomenon. The epithelial sodium channel (ENaC) is a major regulator of sodium reabsorption in the kidney. In this study, human renal tubular epithelial cells (hRTC) were cultured from the urine of phenotyped salt study participants. αENaC expression was significantly lower in ISS than salt resistant (SR) hRTC, while ENaC-like channel activity was dramatically increased by trypsin treatment in ISS cells analyzed by patch clamp. αENaC expression was also decreased under high-salt treatment and increased by aldosterone treatment in ISS cells. Moreover, the αENaC variant, rs4764586, was more prevalent in ISS. In summary, αENaC may be associated with ISS hypertension on low salt. These findings may contribute to understanding the mechanisms of ISS and low salt effect on morbidity and mortality.
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Abd El-Aziz TM, Kaur A, Shapiro MS, Stockand JD, Archer CR. Optogenetic Control of PIP2 Interactions Shaping ENaC Activity. Int J Mol Sci 2022; 23:ijms23073884. [PMID: 35409240 PMCID: PMC8998630 DOI: 10.3390/ijms23073884] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 03/29/2022] [Indexed: 02/06/2023] Open
Abstract
The activity of the epithelial Na+ Channel (ENaC) is strongly dependent on the membrane phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2). PIP2 binds two distinct cationic clusters within the N termini of β- and γ-ENaC subunits (βN1 and γN2). The affinities of these sites were previously determined using short synthetic peptides, yet their role in sensitizing ENaC to changes in PIP2 levels in the cellular system is not well established. We addressed this question by comparing the effects of PIP2 depletion and recovery on ENaC channel activity and intracellular Na+ levels [Na+]i. We tested effects on ENaC activity with mutations to the PIP2 binding sites using the optogenetic system CIBN/CRY2-OCRL to selectively deplete PIP2. We monitored changes of [Na+]i by measuring the fluorescent Na+ indicator, CoroNa Green AM, and changes in channel activity by performing patch clamp electrophysiology. Whole cell patch clamp measurements showed a complete lack of response to PIP2 depletion and recovery in ENaC with mutations to βN1 or γN2 or both sites, compared to wild type ENaC. Whereas mutant βN1 also had no change in CoroNa Green fluorescence in response to PIP2 depletion, γN2 did have reduced [Na+]i, which was explained by having shorter CoroNa Green uptake and half-life. These results suggest that CoroNa Green measurements should be interpreted with caution. Importantly, the electrophysiology results show that the βN1 and γN2 sites on ENaC are each necessary to permit maximal ENaC activity in the presence of PIP2.
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Affiliation(s)
- Tarek Mohamed Abd El-Aziz
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78228, USA; (T.M.A.E.-A.); (M.S.S.); (J.D.S.)
- Faculty of Science, Zoology Department, Minia University, El-Minia 61519, Egypt
| | - Amanpreet Kaur
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA;
| | - Mark S. Shapiro
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78228, USA; (T.M.A.E.-A.); (M.S.S.); (J.D.S.)
| | - James D. Stockand
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78228, USA; (T.M.A.E.-A.); (M.S.S.); (J.D.S.)
| | - Crystal R. Archer
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78228, USA; (T.M.A.E.-A.); (M.S.S.); (J.D.S.)
- Correspondence:
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Pyrshev K, Khayyat NH, Stavniichuk A, Tomilin VN, Zaika O, Ramkumar N, Pochynyuk O. ClC-K2 Cl - channel allows identification of A- and B-type of intercalated cells in split-opened collecting ducts. FASEB J 2022; 36:e22275. [PMID: 35349181 PMCID: PMC9014849 DOI: 10.1096/fj.202200160r] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/01/2022] [Accepted: 03/14/2022] [Indexed: 11/11/2022]
Abstract
The collecting duct is a highly adaptive terminal part of the nephron, which is essential for maintaining systemic homeostasis. Principal and intercalated cells perform different physiological tasks and exhibit distinctive morphology. However, acid-secreting A- and base secreting B-type of intercalated cells cannot be easily separated in functional studies. We used BCECF-sensitive intracellular pH (pHi ) measurements in split-opened collecting ducts followed by immunofluorescent microscopy in WT and intercalated cell-specific ClC-K2-/- mice to demonstrate that ClC-K2 inhibition enables to distinguish signals from A- and B-intercalated cells. We show that ClC-K2 Cl- channel is expressed on the basolateral side of intercalated cells, where it governs Cl- -dependent H+ /HCO3 - transport. ClC-K2 blocker, NPPB, caused acidification or alkalization in different subpopulations of intercalated cells in WT but not ClC-K2-/- mice. Immunofluorescent assessment of the same collecting ducts revealed that NPPB increased pHi in AE1-positive A-type and decreased pHi in pendrin-positive B-type of intercalated cells. Induction of metabolic acidosis led to a significantly augmented abundance and H+ secretion in A-type and decreased proton transport in B-type of intercalated cells, whereas metabolic alkalosis caused the opposite changes in intercalated cell function, but did not substantially change their relative abundance. Overall, we show that inhibition of ClC-K2 can be employed to discriminate between A- and B-type of intercalated cells in split-opened collecting duct preparations. We further demonstrate that this method can be used to independently monitor changes in the functional status and abundance of A- and B-type in response to systemic acid/base stimuli.
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Affiliation(s)
- Kyrylo Pyrshev
- Department of Integrative Biology and Pharmacology, the University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Naghmeh Hassanzadeh Khayyat
- Department of Integrative Biology and Pharmacology, the University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Anna Stavniichuk
- Department of Integrative Biology and Pharmacology, the University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Viktor N Tomilin
- Department of Integrative Biology and Pharmacology, the University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Oleg Zaika
- Department of Integrative Biology and Pharmacology, the University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Nirupama Ramkumar
- Division of Nephrology and Hypertension, University of Utah Health, Salt Lake City, Utah, USA
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology, the University of Texas Health Science Center at Houston, Houston, Texas, USA
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60
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Dong H, Liu J, Zhu J, Zhou Z, Tizzano M, Peng X, Zhou X, Xu X, Zheng X. Oral Microbiota-Host Interaction Mediated by Taste Receptors. Front Cell Infect Microbiol 2022; 12:802504. [PMID: 35425718 PMCID: PMC9004699 DOI: 10.3389/fcimb.2022.802504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 03/07/2022] [Indexed: 11/13/2022] Open
Abstract
Taste receptors, originally identified in taste buds, function as the periphery receptors for taste stimuli and play an important role in food choice. Cohort studies have revealed that single nucleotide polymorphisms of taste receptors such as T1R1, T1R2, T2R38 are associated with susceptibility to oral diseases like dental caries. Recent studies have demonstrated the wide expression of taste receptors in various tissues, including intestinal epithelia, respiratory tract, and gingiva, with an emerging role of participating in the interaction between mucosa surface and microorganisms via monitoring a wide range of metabolites. On the one hand, individuals with different oral microbiomes exhibited varied taste sensitivity, suggesting a potential impact of the oral microbiota composition on taste receptor function. On the other hand, animal studies and in vitro studies have uncovered that a variety of oral cells expressing taste receptors such as gingival solitary chemosensory cells, gingival epithelial cells (GECs), and gingival fibroblasts can detect bacterial signals through bitter taste receptors to trigger host innate immune responses, thus regulating oral microbial homeostasis. This review focuses on how taste receptors, particularly bitter and sweet taste receptors, mediate the oral microbiota-host interaction as well as impact the occurrence and development of oral diseases. Further studies delineating the role of taste receptors in mediating oral microbiota-host interaction will advance our knowledge in oral ecological homeostasis establishment, providing a novel paradigm and treatment target for the better management of dental infectious diseases.
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Affiliation(s)
- Hao Dong
- State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jiaxin Liu
- State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jianhui Zhu
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Hangzhou, China
- Clinical Research Center for Oral Diseases of Zhejiang Province, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Hangzhou, China
| | - Zhiyan Zhou
- State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Marco Tizzano
- Basic and Translation Sciences, Penn Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Xian Peng
- State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xin Xu
- State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- *Correspondence: Xin Zheng, ; Xin Xu,
| | - Xin Zheng
- State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- *Correspondence: Xin Zheng, ; Xin Xu,
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Fronius M. Epithelial Na+ channel and the glycocalyx: a sweet and salty relationship for arterial shear stress sensing. Curr Opin Nephrol Hypertens 2022; 31:142-150. [PMID: 34966089 DOI: 10.1097/mnh.0000000000000779] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW The ability of endothelial cells to sense mechanical force, and shear stress in particular, is crucial for normal vascular function. This relies on an intact endothelial glycocalyx that facilitates the production of nitric oxide (NO). An emerging arterial shear stress sensor is the epithelial Na+ channel (ENaC). This review highlights existing and new evidence for the interdependent activity of the glycocalyx and ENaC and its implications for vascular function. RECENT FINDINGS New evidence suggests that the glycocalyx and ENaC are physically connected and that this is important for shear stress sensing. The connection relies on N-glycans attached to glycosylated asparagines of α-ENaC. Removal of specific N-glycans reduced ENaC's shear stress response. Similar effects were observed following degradation of the glycocalyx. Endothelial specific viral transduction of α-ENaC increased blood pressure (∼40 mmHg). This increase was attenuated in animals transduced with an α-ENaC version lacking N-glycans. SUMMARY These observations indicate that ENaC is connected to the glycocalyx and their activity is interdependent to facilitate arterial shear stress sensation. Future research focusing on how N-glycans mediate this interaction can provide new insights for the understanding of vascular function in health and disease.
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Affiliation(s)
- Martin Fronius
- Department of Physiology, School of Biomedical Sciences
- HeartOtago, University of Otago, Dunedin
- Healthy Hearts Aotearoa New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, Centre of Research Excellence, Auckland, New Zealand
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62
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Matsubara A, Miyashita T, Nakashima K, Mori N, Song SY, Hoshikawa H. Low-salt diet increases mRNA expression of aldosterone-regulated transporters in the intermediate portion of the endolymphatic sac. Pflugers Arch 2022; 474:505-515. [PMID: 35112133 DOI: 10.1007/s00424-021-02661-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 12/08/2021] [Accepted: 12/23/2021] [Indexed: 11/29/2022]
Abstract
The endolymphatic sac is a small sac-shaped organ at the end of the membranous labyrinth of the inner ear. The endolymphatic sac absorbs the endolymph, in which the ion balance is crucial for inner ear homeostasis. Of the three sections of the endolymphatic sac, the intermediate portion is the center of endolymph absorption, particularly sodium transport, and is thought to be regulated by aldosterone. Disorders of the endolymphatic sac may cause an excess of endolymph (endolymphatic hydrops), a histological observation in Meniere's disease. A low-salt diet is an effective treatment for Meniere's disease, and is based on the assumption that the absorption of endolymph in the endolymphatic sac abates endolymphatic hydrops through a physiological increase in aldosterone level. However, the molecular basis of endolymph absorption in each portion of the endolymphatic sac is largely unknown because of difficulties in gene expression analysis, resulting from its small size and intricate structure. The present study combined reverse transcription-quantitative polymerase chain reaction and laser capture microdissection techniques to analyze the difference of gene expression of the aldosterone-controlled epithelial Na+ channel, thiazide-sensitive Na+-Cl- cotransporter, and Na+, K+-ATPase genes in the three individual portions of the endolymphatic sac in a rat model. A low-salt diet increased the expression of aldosterone-controlled ion transporters, particularly in the intermediate portion of the endolymphatic sac. Our findings will contribute to the understanding of the physiological function of the endolymphatic sac and the pathophysiology of Meniere's disease.
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Affiliation(s)
- Ai Matsubara
- Department of Otolaryngology, Faculty of Medicine, Kagawa University, Ikenobe 1750-1, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan.
| | - Takenori Miyashita
- Department of Otolaryngology, Faculty of Medicine, Kagawa University, Ikenobe 1750-1, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan
| | - Kentaro Nakashima
- Institute of Neuroscience, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa, Japan
| | - Nozomu Mori
- Department of Otolaryngology, Faculty of Medicine, Kagawa University, Ikenobe 1750-1, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan
| | - Si-Young Song
- Institute of Neuroscience, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa, Japan
| | - Hiroshi Hoshikawa
- Department of Otolaryngology, Faculty of Medicine, Kagawa University, Ikenobe 1750-1, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan
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63
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Kelchtermans J, Pinney SE, Leonard JMM, Mcgrath-Morrow S. Diagnostic and management considerations in pseudohypoaldosteronism type 1b. BMJ Case Rep 2022; 15:e246538. [PMID: 34980640 PMCID: PMC8724702 DOI: 10.1136/bcr-2021-246538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2021] [Indexed: 11/04/2022] Open
Abstract
Pseudohypoaldosteronism type 1B is a rare autosomal recessive disorder caused by dysfunction of amiloride-sensitive epithelial sodium channels (ENaCs). We present the case of a neonate with cardiogenic shock after cardiac arrest due to profound hyperkalaemia. Genetic testing revealed a novel homozygous variant in SCNNIA We review diagnostic considerations including the molecular mechanisms of disease, discuss treatment approaches and highlight the possible significance of the diversity of pulmonary ENaCs.
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Affiliation(s)
- Jelte Kelchtermans
- Division of Pulmonary and Sleep Medicine, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Sara E Pinney
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Division of Endocrinology and Diabetes, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Jacqueline M M Leonard
- Roberts Individualized Medical Genetics Center, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Sharon Mcgrath-Morrow
- Division of Pulmonary and Sleep Medicine, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
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64
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Ridley J, Manyweathers S, Tang R, Goetze T, Becker N, Rinke-Weiß I, Kirby R, Obergrussberger A, Rogers M. Development of ASIC1a ligand-gated ion channel drug screening assays across multiple automated patch clamp platforms. Front Mol Neurosci 2022; 15:982689. [PMID: 36340694 PMCID: PMC9629855 DOI: 10.3389/fnmol.2022.982689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 09/12/2022] [Indexed: 02/05/2023] Open
Abstract
Human acid-sensing ion channels (ASIC) are ligand-gated ionotropic receptors expressed widely in peripheral tissues as well as sensory and central neurons and implicated in detection of inflammation, tissue injury, and hypoxia-induced acidosis. This makes ASIC channels promising targets for drug discovery in oncology, pain and ischemia, and several modulators have progressed into clinical trials. We describe the use of hASIC1a as a case study for the development and validation of low, medium and high throughput automated patch clamp (APC) assays suitable for the screening and mechanistic profiling of new ligands for this important class of ligand-gated ion channel. Initial efforts to expand on previous manual patch work describing an endogenous hASIC1a response in HEK cells were thwarted by low current expression and unusual pharmacology, so subsequent work utilized stable hASIC1a CHO cell lines. Ligand-gated application protocols and screening assays on the Patchliner, QPatch 48, and SyncroPatch 384 were optimized and validated based on pH activation and nM-μM potency of reference antagonists (e.g., Amiloride, Benzamil, Memantine, Mambalgin-3, A-317567, PcTx1). By optimizing single and stacked pipette tip applications available on each APC platform, stable pH-evoked currents during multiple ligand applications enabled cumulative EC50 and IC50 determinations with minimized receptor desensitization. Finally, we successfully demonstrated for the first time on an APC platform the ability to use current clamp to implement the historical technique of input resistance tracking to measure ligand-gated changes in membrane conductance on the Patchliner platform.
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Affiliation(s)
- John Ridley
- Metrion Biosciences Ltd., Cambridge, United Kingdom
| | | | - Raymond Tang
- Metrion Biosciences Ltd., Cambridge, United Kingdom
| | - Tom Goetze
- Nanion Technologies GmbH, Munich, Germany
| | | | | | - Robert Kirby
- Metrion Biosciences Ltd., Cambridge, United Kingdom
| | | | - Marc Rogers
- Metrion Biosciences Ltd., Cambridge, United Kingdom
- *Correspondence: Marc Rogers,
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Tsilosani A, Gao C, Zhang W. Aldosterone-Regulated Sodium Transport and Blood Pressure. Front Physiol 2022; 13:770375. [PMID: 35197862 PMCID: PMC8859437 DOI: 10.3389/fphys.2022.770375] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 01/06/2022] [Indexed: 11/13/2022] Open
Abstract
Aldosterone is a major mineralocorticoid steroid hormone secreted by glomerulosa cells in the adrenal cortex. It regulates a variety of physiological responses including those to oxidative stress, inflammation, fluid disruption, and abnormal blood pressure through its actions on various tissues including the kidney, heart, and the central nervous system. Aldosterone synthesis is primarily regulated by angiotensin II, K+ concentration, and adrenocorticotrophic hormone. Elevated serum aldosterone levels increase blood pressure largely by increasing Na+ re-absorption in the kidney through regulating transcription and activity of the epithelial sodium channel (ENaC). This review focuses on the signaling pathways involved in aldosterone synthesis and its effects on Na+ reabsorption through ENaC.
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Affiliation(s)
- Akaki Tsilosani
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
| | - Chao Gao
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
| | - Wenzheng Zhang
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
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Zhang DD, Zheng JY, Duan XP, Lin DH, Wang WH. ROMK channels are inhibited in the aldosterone-sensitive distal nephron of renal tubule Nedd4-2-deficient mice. Am J Physiol Renal Physiol 2022; 322:F55-F67. [PMID: 34843409 PMCID: PMC8714254 DOI: 10.1152/ajprenal.00306.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 11/18/2021] [Accepted: 11/27/2021] [Indexed: 01/03/2023] Open
Abstract
We used whole cell recording to examine the renal outer medullary K+ channel (ROMK or Kir1.1) and epithelial Na+ channel (ENaC) in the late distal convoluted tubule (DCT2)/initial connecting tubule (iCNT) and in the cortical collecting duct (CCD) of kidney tubule-specific neural precursor cell-expressed developmentally downregulated protein 4-2 (Nedd4-2) knockout mice (Ks-Nedd4-2 KO) and floxed neural precursor cell-expressed developmentally downregulated 4-like (Nedd4l) mice (control). Tertiapin Q (TPNQ)-sensitive K+ currents (ROMK) were smaller in both the DCT2/iCNT and CCD of Ks-Nedd4-2 KO mice on a normal diet than in control mice. Neither high dietary salt intake nor low dietary salt intake had a significant effect on ROMK activity in the DCT2/iCNT and CCD of control and Ks-Nedd4-2 KO mice. In contrast, high dietary K+ intake (HK) increased, whereas low dietary K+ intake (LK) decreased TPNQ-sensitive K+ currents in floxed Nedd4l mice. However, the effects of dietary K+ intake on ROMK channel activity were absent in Ks-Nedd4-2 KO mice since neither HK nor LK significantly affected TPNQ-sensitive K+ currents in the DCT2/iCNT and CCD. Moreover, TPNQ-sensitive K+ currents in the DCT2/iCNT and CCD of Ks-Nedd4-2 KO mice on HK were similar to those of control mice on LK. Amiloride-sensitive Na+ currents in the DCT2/iCNT and CCD were significantly higher in Ks-Nedd4-2 KO mice than in floxed Nedd4l mice on a normal K+ diet. HK increased ENaC activity of the DCT2/iCNT only in control mice, but HK stimulated ENaC of the CCD in both control and Ks-Nedd4-2 KO mice. Moreover, the HK-induced increase in amiloride-sensitive Na+ currents was larger in Ks-Nedd4-2 KO mice than in control mice. Deletion of Nedd4-2 increased with no lysine kinase 1 expression and abolished HK-induced inhibition of with no lysine kinase 1. We conclude that deletion of Nedd4-2 increases ENaC activity but decreases ROMK activity in the aldosterone-sensitive distal nephron and that HK fails to stimulate ROMK, but robustly increases ENaC activity in the CCD of Nedd4-2-deficient mice.NEW & NOTEWORTHY We demonstrate that renal outer medullary K+ (ROMK) channel activity is inhibited in the late distal convoluted tubule/initial connecting tubule and cortical collecting duct of neural precursor cell-expressed developmentally downregulated protein 4-2 (Nedd4-2)-deficient mice. Also, deletion of Nedd4-2 abolishes the stimulatory effect of dietary K+ intake on ROMK. The lack of high K+-induced stimulation of ROMK is associated with the absence of high K+-induced inhibition of with no lysine kinase 1.
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Affiliation(s)
- Dan-Dan Zhang
- Guangdong-Hong Kong Joint Laboratory on Immunological and Genetic Kidney Diseases, Guangdong Academy of Medical Sciences, Guangdong Provincial People's Hospital, Guangzhou, Guangdong, China
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Jun-Ya Zheng
- Department of Endocrinology, First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Xin-Peng Duan
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
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Zhang D, Qu Y, Dong XQ, Lu YT, Yang KQ, Liu XC, Fan P, Hu YX, Yang CX, Gao LG, Liu YX, Zhou XL. Pathogenicity and Long-Term Outcomes of Liddle Syndrome Caused by a Nonsense Mutation of SCNN1G in a Chinese Family. Front Pediatr 2022; 10:887214. [PMID: 35685915 PMCID: PMC9170920 DOI: 10.3389/fped.2022.887214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 05/02/2022] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVE Liddle syndrome (LS) is a monogenic hypertension consistent with autosomal dominant inheritance, often with early onset high blood pressure in childhood or adolescence. This study aimed to identify the pathogenicity of a nonsense mutation in SCNN1G in a Chinese family with LS and the long-term outcomes of tailored treatment with amiloride. METHODS To explore the pathogenicity of candidate variant reported in 2015 by our team, we constructed mutant and wild-type models in vitro and measured amiloride-sensitive current in Chinese Hamster Ovary (CHO) cells using patch clamp technique. Participants were followed up for 7 years after tailored treatment with amiloride. RESULTS A nonsense variant was detected in six members, two of whom were pediatric patients. This mutation resulted in a termination codon at codon 572, truncating the Pro-Pro-Pro-X-Tyr motif. The mutant epithelial sodium channels displayed higher amiloride-sensitive currents than the wild-type channels (P < 0.05). Tailored treatment with amiloride achieved ideal blood pressure control in all patients with normal cardiorenal function, and no adverse events occurred during follow-up. CONCLUSION We found the pathogenicity of a nonsense SCNN1G mutation (p.Glu571*) with enhanced amiloride-sensitive currents in a LS family with young patients. Tailored treatment with amiloride may be an effective strategy for the long-term control of blood pressure and protection from target organ damage or cardiovascular events, including children and youth patients with LS.
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Affiliation(s)
- Di Zhang
- Department of Cardiology, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China
| | - Yi Qu
- Department of Cardiology, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China
| | - Xue-Qi Dong
- Department of Cardiology, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China
| | - Yi-Ting Lu
- Department of Cardiology, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China
| | - Kun-Qi Yang
- Department of Cardiology, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China
| | - Xin-Chang Liu
- Department of Cardiology, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China
| | - Peng Fan
- Department of Cardiology, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China
| | - Yu-Xiao Hu
- Emergency and Critical Care Center, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China
| | - Chun-Xue Yang
- Emergency and Critical Care Center, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China
| | - Ling-Gen Gao
- Department of Geriatric Cardiology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China
| | - Ya-Xin Liu
- Emergency and Critical Care Center, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing, China
| | - Xian-Liang Zhou
- Department of Geriatric Cardiology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China
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Shi S, Buck TM, Nickerson AJ, Brodsky JL, Kleyman TR. Paraoxonase 2 is an ER chaperone that regulates the epithelial Na + channel. Am J Physiol Cell Physiol 2022; 322:C111-C121. [PMID: 34852210 PMCID: PMC8759969 DOI: 10.1152/ajpcell.00335.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The mammalian paraoxonases (PONs) have been linked to protection against oxidative stress. However, the physiological roles of members in this family (PON1, PON2, and PON3) are still being characterized. PON2 and PON3 are expressed in the aldosterone-sensitive distal nephron of the kidney and have been shown to negatively regulate expression of the epithelial sodium channel (ENaC), a trimeric ion channel that orchestrates salt and water homeostasis. To date, the nature of this phenomenon has not been explored. Therefore, to investigate the mechanism by which PON2 regulates ENaC, we expressed PON2 along with the ENaC subunits in fisher rat thyroid (FRT) cells, a system that is amenable to biochemical analyses of ENaC assembly and trafficking. We found that PON2 primarily resides in the endoplasmic reticulum (ER) in FRT cells, and its expression reduces the abundance of each ENaC subunit, reflecting enhanced subunit turnover. In contrast, no effect on the levels of mRNAs encoding the ENaC subunits was evident. Inhibition of lysosome function with chloroquine or NH4Cl did not alter the inhibitory effect of PON2 on ENaC expression. In contrast, PON2 accelerates ENaC degradation in a proteasome-dependent manner and acts before ENaC subunit ubiquitination. As a result of enhanced ENaC subunit ubiquitination and degradation, both channel surface expression and ENaC-mediated Na+ transport in FRT cells were reduced by PON2. Together, our data suggest that PON2 functions as an ER chaperone to monitor ENaC biogenesis and redirects the channel for ER-associated degradation.
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Affiliation(s)
- Shujie Shi
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Teresa M. Buck
- 2Deparment of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Andrew J. Nickerson
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Jeffrey L. Brodsky
- 2Deparment of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Thomas R. Kleyman
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania,3Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania,4Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
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Dizin E, Olivier V, Roth I, Sassi A, Arnoux G, Ramakrishnan S, Morel S, Kwak BR, Loffing J, Hummler E, Wenger RH, Frew IJ, Feraille E. Activation of the Hypoxia-Inducible Factor Pathway Inhibits Epithelial Sodium Channel-Mediated Sodium Transport in Collecting Duct Principal Cells. J Am Soc Nephrol 2021; 32:3130-3145. [PMID: 34615708 PMCID: PMC8638392 DOI: 10.1681/asn.2021010046] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 08/18/2021] [Accepted: 09/05/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Active sodium reabsorption is the major factor influencing renal oxygen consumption and production of reactive oxygen species (ROS). Increased sodium reabsorption uses more oxygen, which may worsen medullary hypoxia and produce more ROS via enhanced mitochondrial ATP synthesis. Both mechanisms may activate the hypoxia-inducible factor (HIF) pathway. Because the collecting duct is exposed to low oxygen pressure and variations of active sodium transport, we assessed whether the HIF pathway controls epithelial sodium channel (ENaC)-dependent sodium transport. METHODS We investigated HIF's effect on ENaC expression in mpkCCD cl4 cells (a model of collecting duct principal cells) using real-time PCR and western blot and ENaC activity by measuring amiloride-sensitive current. We also assessed the effect of hypoxia and sodium intake on abundance of kidney sodium transporters in wild-type and inducible kidney tubule-specific Hif1α knockout mice. RESULTS In cultured cells, activation of the HIF pathway by dimethyloxalylglycine or hypoxia inhibited sodium transport and decreased expression of β ENaC and γ ENaC, as well as of Na,K-ATPase. HIF1 α silencing increased β ENaC and γ ENaC expression and stimulated sodium transport. A constitutively active mutant of HIF1 α produced the opposite effect. Aldosterone and inhibition of the mitochondrial respiratory chain slowly activated the HIF pathway, suggesting that ROS may also activate HIF. Decreased γ ENaC abundance induced by hypoxia in normal mice was abolished in Hif1α knockout mice. Similarly, Hif1α knockout led to increased γ ENaC abundance under high sodium intake. CONCLUSIONS This study reveals that γ ENaC expression and activity are physiologically controlled by the HIF pathway, which may represent a negative feedback mechanism to preserve oxygenation and/or prevent excessive ROS generation under increased sodium transport.
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Affiliation(s)
- Eva Dizin
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland,National Centre of Competence in Research “Kidney.CH”, Switzerland
| | - Valérie Olivier
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland,National Centre of Competence in Research “Kidney.CH”, Switzerland
| | - Isabelle Roth
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland,National Centre of Competence in Research “Kidney.CH”, Switzerland
| | - Ali Sassi
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland,National Centre of Competence in Research “Kidney.CH”, Switzerland
| | - Grégoire Arnoux
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland,National Centre of Competence in Research “Kidney.CH”, Switzerland
| | - Suresh Ramakrishnan
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland,National Centre of Competence in Research “Kidney.CH”, Switzerland
| | - Sandrine Morel
- Department of Pathology and Immunology, University of Geneva, CMU, Geneva, Switzerland
| | - Brenda R. Kwak
- Department of Pathology and Immunology, University of Geneva, CMU, Geneva, Switzerland
| | - Johannes Loffing
- National Centre of Competence in Research “Kidney.CH”, Switzerland,Institute of Anatomy, University of Zürich, Zürich, Switzerland
| | - Edith Hummler
- National Centre of Competence in Research “Kidney.CH”, Switzerland,Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Roland H. Wenger
- National Centre of Competence in Research “Kidney.CH”, Switzerland,Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Ian J. Frew
- Department of Internal Medicine I, Hematology, Oncology and Stem Cell Transplantation, Faculty of Medicine, Medical Centre - University of Freiburg, Freiburg, Germany
| | - Eric Feraille
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland,National Centre of Competence in Research “Kidney.CH”, Switzerland
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Aguado-García A, Priego-Espinosa DA, Aldana A, Darszon A, Martínez-Mekler G. Mathematical model reveals that heterogeneity in the number of ion transporters regulates the fraction of mouse sperm capacitation. PLoS One 2021; 16:e0245816. [PMID: 34793454 PMCID: PMC8601445 DOI: 10.1371/journal.pone.0245816] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Accepted: 10/20/2021] [Indexed: 12/03/2022] Open
Abstract
Capacitation is a complex maturation process mammalian sperm must undergo in the female genital tract to be able to fertilize an egg. This process involves, amongst others, physiological changes in flagellar beating pattern, membrane potential, intracellular ion concentrations and protein phosphorylation. Typically, in a capacitation medium, only a fraction of sperm achieve this state. The cause for this heterogeneous response is still not well understood and remains an open question. Here, one of our principal results is to develop a discrete regulatory network, with mostly deterministic dynamics in conjunction with some stochastic elements, for the main biochemical and biophysical processes involved in the early events of capacitation. The model criterion for capacitation requires the convergence of specific levels of a select set of nodes. Besides reproducing several experimental results and providing some insight on the network interrelations, the main contribution of the model is the suggestion that the degree of variability in the total amount and individual number of ion transporters among spermatozoa regulates the fraction of capacitated spermatozoa. This conclusion is consistent with recently reported experimental results. Based on this mathematical analysis, experimental clues are proposed for the control of capacitation levels. Furthermore, cooperative and interference traits that become apparent in the modelling among some components also call for future theoretical and experimental studies.
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Affiliation(s)
- Alejandro Aguado-García
- Instituto de Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | | | - Andrés Aldana
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, CDMX, México
| | - Alberto Darszon
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Gustavo Martínez-Mekler
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, CDMX, México
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Laselva O, Guerra L, Castellani S, Favia M, Di Gioia S, Conese M. Small-molecule drugs for cystic fibrosis: Where are we now? Pulm Pharmacol Ther 2021; 72:102098. [PMID: 34793977 DOI: 10.1016/j.pupt.2021.102098] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 10/24/2021] [Accepted: 11/12/2021] [Indexed: 01/05/2023]
Abstract
The cystic fibrosis (CF) lung disease is due to the lack/dysfunction of the CF Transmembrane Conductance Regulator (CFTR), a chloride channel expressed by epithelial cells as the main regulator of ion and fluid homeostasis. More than 2000 genetic variation in the CFTR gene are known, among which those with identified pathomechanism have been divided into six VI mutation classes. A major advancement in the pharmacotherapy of CF has been the development of small-molecule drugs hitting the root of the disease, i.e. the altered ion and fluid transport through the airway epithelium. These drugs, called CFTR modulators, have been advanced to the clinics to treat nearly 90% of CF patients, including the CFTR potentiator ivacaftor, approved for residual function mutations (Classes III and IV), and combinations of correctors (lumacaftor, tezacaftor, elexacaftor) and ivacaftor for patients bearing at least one the F508del mutation, the most frequent mutation belonging to class II. To cover the 10% of CF patients without etiological therapies, other novel small-molecule CFTR modulators are in evaluation of their effectiveness in all the CFTR mutation classes: read-through agents for Class I, correctors, potentiators and amplifiers from different companies for Class II-V, stabilizers for Class VI. In alternative, other solute carriers, such as SLC26A9 and SLC6A14, are the focus of intensive investigation. Finally, other molecular targets are being evaluated for patients with no approved CFTR modulator therapy or as means of enhancing CFTR modulatory therapy, including small molecules forming ion channels, inhibitors of the ENaC sodium channel and potentiators of the calcium-activated chloride channel TMEM16A. This paper aims to give an up-to-date overview of old and novel CFTR modulators as well as of novel strategies based on small-molecule drugs. Further investigations in in-vivo and cell-based models as well as carrying out large prospective studies will be required to determine if novel CFTR modulators, stabilizers, amplifiers, and the ENaC inhibitors or TMEM16A potentiators will further improve the clinical outcomes in CF management.
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Affiliation(s)
- Onofrio Laselva
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Lorenzo Guerra
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Stefano Castellani
- Department of Medical Sciences and Human Oncology, University of Bari, Bari, Italy
| | - Maria Favia
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Sante Di Gioia
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Massimo Conese
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy.
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72
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Chang J, Hu X, Nan J, Zhang X, Jin X. HOXD9‑induced SCNN1A upregulation promotes pancreatic cancer cell proliferation, migration and predicts prognosis by regulating epithelial‑mesenchymal transformation. Mol Med Rep 2021; 24:819. [PMID: 34558641 PMCID: PMC8477178 DOI: 10.3892/mmr.2021.12459] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 05/24/2021] [Indexed: 12/13/2022] Open
Abstract
Pancreatic cancer (PC) is a malignant tumor disease, whose molecular mechanism is not fully understood. Sodium channel epithelial 1α subunit (SCNN1A) serves an important role in tumor progression. The current study explored the role of homeobox D9 (HOXD9) and SCNN1A in the progression of PC. The expression of SCNN1A and HOXD9 in PC samples was predicted on online databases and detected in PC cell lines. The association between SCNN1A expression and PC prognosis was examined by the Gene Expression Profiling Interactive Analysis, The Cancer Genome Atlas and Genotype‑Tissue Expression databases and by a Kaplan‑Meier plotter. Subsequently, the biological effects of SCNN1A on PC cell growth, colony formation, migration and invasion were investigated through RNA interference and cell transfection. Next, the expression of E‑cadherin, N‑cadherin, Vimentin and Snail was detected by western blotting to discover whether HOXD9 dysregulation mediated PC metastasis. Binding sites of HOXD9 and SCNN1A promoters were predicted on JASPAR. Reverse transcription‑quantitative PCR and western blotting were used to detect the expression level of SCNN1A following interference and overexpression of HOXD9. Luciferase assay detected luciferase activity following interference with HOXD9 and the transcriptional activity of SCNN1A following binding site deletion. High expression of SCNN1A and HOXD9 in PC was predicted by online databases, signifying poor prognosis. The present study confirmed the above predictions in PC cell lines. Knockdown of SCNN1A and HOXD9 could effectively inhibit the proliferation, migration, invasion and epithelial‑mesenchymal transition of PC cells. Furthermore, HOXD9 activated SCNN1A transcription, forming a feedback regulatory loop. HOXD9 was demonstrated to activate SCNN1A and promote the malignant biological process of PC.
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Affiliation(s)
- Jinhai Chang
- Department of Internal Medicine, Yanbian Hospital of Traditional Chinese Medicine, Yanbian, Jilin 133000, P.R. China
| | - Xuguang Hu
- Department of Hepatobiliary Surgery, Jiangxi Cancer Hospital, Nanchang, Jiangxi 330029, P.R. China
| | - Jinniang Nan
- Department of Clinical Medicine, Jiangxi Health Vocational College of China, Nanchang, Jiangxi 330052, P.R. China
- Correspondence to: Dr Jinniang Nan, Department of Clinical Medicine, Jiangxi Health Vocational College of China, 689 Huiren Avenue, Xiaolan Economic Development Zone, Nanchang, Jiangxi 330052, P.R. China, E-mail:
| | - Xianghua Zhang
- Department of Thoracic Oncology, Jilin Province Cancer Hospital, Changchun, Jilin 130000, P.R. China
| | - Xintian Jin
- Department of Thoracic Surgery, Jilin Province Cancer Hospital, Changchun, Jilin 130000, P.R. China
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73
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Ibuprofen inhibits oral NaCl response through transmembrane channel-like 4. Biochem Biophys Res Commun 2021; 573:76-79. [PMID: 34411898 DOI: 10.1016/j.bbrc.2021.07.082] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 07/23/2021] [Indexed: 01/24/2023]
Abstract
Nonsteroidal anti-inflammatory drugs, such as ibuprofen, are known to modify salty taste perception in humans. However, the underlying molecular mechanisms remain unknown. We investigated the inhibitory effect of ibuprofen on the NaCl stimulation of epithelium sodium channel (ENaC) and transmembrane channel-like 4 (TMC4), which are involved in salty taste detection. Although ibuprofen only minimally inhibited the response of the ENaC to NaCl, it significantly inhibited the TMC4 response to NaCl with an IC50 at 1.45 mM. These results suggest that ibuprofen interferes with detection of salty taste via inhibition of TMC4.
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74
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Consistent Assignment of Risk and Benign Allele at rs2303153 in the CF Modifier Gene SCNN1B in Three Independent F508del- CFTR Homozygous Patient Populations. Genes (Basel) 2021; 12:genes12101554. [PMID: 34680949 PMCID: PMC8535344 DOI: 10.3390/genes12101554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/27/2021] [Accepted: 09/28/2021] [Indexed: 11/17/2022] Open
Abstract
CFTR encodes for a chloride and bicarbonate channel expressed at the apical membrane of polarized epithelial cells. Transepithelial sodium transport mediated by the amiloride-sensitive sodium channel ENaC is thought to contribute to the manifestation of CF disease. Thus, ENaC is a therapeutic target in CF and a valid cystic fibrosis modifier gene. We have characterized SCNN1B as a genetic modifier in the three independent patient cohorts of F508del-CFTR homozygotes. We could identify a regulatory element at SCNN1B to the genomic segment rs168748-rs2303153-rs4968000 by fine-mapping (Pbest = 0.0177), consistently observing the risk allele rs2303153-C and the contrasting benign allele rs2303153-G in all three patient cohorts. Furthermore, our results show that expression levels of SCNN1B are associated with rs2303153 genotype in intestinal epithelia (p = 0.003). Our data confirm that the well-established biological role of SCNN1B can be recognized by an association study on informative endophenotypes in the rare disease cystic fibrosis and calls attention to reproducible results in association studies obtained from small, albeit carefully characterized patient populations.
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75
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Soares AG, Contreras J, Archer CR, Mironova E, Berdeaux R, Stockand JD, Abd El-Aziz TM. Stimulation of the Epithelial Na + Channel in Renal Principal Cells by Gs-Coupled Designer Receptors Exclusively Activated by Designer Drugs. Front Physiol 2021; 12:725782. [PMID: 34512393 PMCID: PMC8425396 DOI: 10.3389/fphys.2021.725782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 07/28/2021] [Indexed: 11/29/2022] Open
Abstract
The activity of the Epithelial Na+ Channel (ENaC) in renal principal cells (PC) fine-tunes sodium excretion and consequently, affects blood pressure. The Gs-adenylyl cyclase-cAMP signal transduction pathway is believed to play a central role in the normal control of ENaC activity in PCs. The current study quantifies the importance of this signaling pathway to the regulation of ENaC activity in vivo using a knock-in mouse that has conditional expression of Gs-DREADD (designer receptors exclusively activated by designer drugs; GsD) in renal PCs. The GsD mouse also contains a cAMP response element-luciferase reporter transgene for non-invasive bioluminescence monitoring of cAMP signaling. Clozapine N-oxide (CNO) was used to selectively and temporally stimulate GsD. Treatment with CNO significantly increased luciferase bioluminescence in the kidneys of PC-specific GsD but not control mice. CNO also significantly increased the activity of ENaC in principal cells in PC-specific GsD mice compared to untreated knock-in mice and CNO treated littermate controls. The cell permeable cAMP analog, 8-(4-chlorophenylthio)adenosine 3′,5′-cyclic monophosphate, significantly increased the activity and expression in the plasma membrane of recombinant ENaC expressed in CHO and COS-7 cells, respectively. Treatment of PC-specific GsD mice with CNO rapidly and significantly decreased urinary Na+ excretion compared to untreated PC-specific GsD mice and treated littermate controls. This decrease in Na+ excretion in response to CNO in PC-specific GsD mice was similar in magnitude and timing as that induced by the selective vasopressin receptor 2 agonist, desmopressin, in wild type mice. These findings demonstrate for the first time that targeted activation of Gs signaling exclusively in PCs is sufficient to increase ENaC activity and decrease dependent urinary Na+ excretion in live animals.
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Affiliation(s)
- Antonio G Soares
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Jorge Contreras
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Crystal R Archer
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Elena Mironova
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Rebecca Berdeaux
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - James D Stockand
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Tarek Mohamed Abd El-Aziz
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.,Zoology Department, Faculty of Science, Minia University, Minya, Egypt
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76
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Latorre-Estivalis JM, Almeida FC, Pontes G, Dopazo H, Barrozo RB, Lorenzo MG. Evolution of the insect PPK gene family. Genome Biol Evol 2021; 13:6352500. [PMID: 34390578 PMCID: PMC8438182 DOI: 10.1093/gbe/evab185] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/05/2021] [Indexed: 11/12/2022] Open
Abstract
Insect pickpocket (PPK) receptors mediate diverse functions, among them the detection of mechano- and chemo-sensory stimuli. Notwithstanding their relevance, studies on their evolution only focused on Drosophila. We have analyzed the genomes of 26 species of 8 orders including holometabolous and hemimetabolous insects (Blattodea, Orthoptera, Hemiptera, Phthiraptera, Hymenoptera, Lepidoptera, Coleoptera, and Diptera), to characterize the evolution of this gene family. PPKs were detected in all genomes analyzed, with 578 genes distributed in 7 subfamilies. According to our phylogeny ppk17 is the most divergent member, composing the new subfamily VII. PPKs evolved under a gene birth-and-death model that generated lineage-specific expansions usually located in clusters, while purifying selection affected several orthogroups. Subfamily V was the largest, including a mosquito-specific expansion that can be considered a new target for pest control. PPKs present a high gene turnover generating considerable variation. On one hand, Musca domestica (59), Aedes albopictus (51), Culex quinquefasciatus (48), and Blattella germanica (41) presented the largest PPK repertoires. On the other hand, Pediculus humanus (only ppk17), bees and ants (6-9) had the smallest PPK sets. A subset of prevalent PPKs was identified, indicating very conserved functions for these receptors. Finally, at least twenty percent of the sequences presented calmodulin-binding motifs, suggesting that these PPKs may amplify sensory responses similarly as proposed for D. melanogaster ppk25. Overall, this work characterized the evolutionary history of these receptors revealing relevant unknown gene sequence features and clade-specific expansions.
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Affiliation(s)
- Jose Manuel Latorre-Estivalis
- Laboratorio de Insectos Sociales, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIByNE), Universidad de Buenos Aires - CONICET, Buenos Aires, Argentina
| | - Francisca C Almeida
- Laboratorio de Genética Evolutiva, Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Gina Pontes
- Laboratorio de Eco-Fisiología de Insectos del Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA-CONICET), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Hernán Dopazo
- Laboratorio de Genómica de Poblaciones y Evolución. Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA). CONICET. Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Argentina
| | - Romina B Barrozo
- Grupo de Neuroetología de Insectos Vectores, Laboratorio de Fisiología de Insectos, Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA - UBA - CONICET), Departamento de Biología y Biodiversidad Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Marcelo Gustavo Lorenzo
- Vector Behaviour and Pathogen Interaction Group, Instituto René Rachou - FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil
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77
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Laube M, Dornis D, Wenzel F, Thome UH. Epidermal growth factor strongly affects epithelial Na + transport and barrier function in fetal alveolar cells, with minor sex-specific effects. Sci Rep 2021; 11:15951. [PMID: 34354180 PMCID: PMC8342687 DOI: 10.1038/s41598-021-95410-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 07/18/2021] [Indexed: 12/15/2022] Open
Abstract
Male sex remains an independent risk factor for respiratory distress syndrome (RDS) in preterm infants. Insufficient Na+ transport-mediated alveolar fluid clearance contributes to RDS development and we previously demonstrated sex-specific differences in Na+ transport. The epidermal growth factor (EGF) is important during fetal lung development with possible influence on Na+ transport. Sex-specific effects of EGF during surfactant synthesis were shown. We thus determined whether EGF exerts sex-specific effects on Na+ transport in fetal alveolar cells. We analyzed sex-specific fetal distal lung epithelial (FDLE) cells exposed to EGF and related ligands with Ussing chambers, RT-qPCR and Western blots. EGF strongly reduced the epithelial Na+ channel (ENaC) mRNA levels in both male and female FDLE cells. This was corroborated by a markedly reduced ENaC activity, while amiloride-insensitive pathways as well as barrier function were raised by EGF. In contrast to chronic effects, acute effects of EGF were sex-specific, because Na+ transport was reduced only in males. AKT phosphorylation was elevated only in female cells, while pERK1/2 was increased in both male and female cells. EGF showed certain sex- and time-dependent effects in FDLE cells. Nevertheless, the results suggest that EGF is an unlikely cause for the sex-specific differences in Na+ transport.
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Affiliation(s)
- Mandy Laube
- Department of Pediatrics, Division of Neonatology, Center for Pediatric Research Leipzig (CPL), University of Leipzig, Liebigstrasse 19, 04103, Leipzig, Germany.
| | - Diana Dornis
- Department of Pediatrics, Division of Neonatology, Center for Pediatric Research Leipzig (CPL), University of Leipzig, Liebigstrasse 19, 04103, Leipzig, Germany
| | - Fine Wenzel
- Department of Pediatrics, Division of Neonatology, Center for Pediatric Research Leipzig (CPL), University of Leipzig, Liebigstrasse 19, 04103, Leipzig, Germany
| | - Ulrich H Thome
- Department of Pediatrics, Division of Neonatology, Center for Pediatric Research Leipzig (CPL), University of Leipzig, Liebigstrasse 19, 04103, Leipzig, Germany
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78
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Gupta N, Prasad P. Hyperkalemia in diabetes: newer insights into mechanism and treatment. Postgrad Med J 2021; 98:e45. [PMID: 37063000 DOI: 10.1136/postgradmedj-2021-140226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2021] [Indexed: 11/04/2022]
Affiliation(s)
- Nimish Gupta
- Nephrology, Metro Heart Institute with Multispeciality, Faridabad, Haryana, India
| | - Pallavi Prasad
- Nephrology, Sri Ramachandra Medical College and Research Institute, Chennai, Tamil Nadu, India
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79
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Zhang J, Yuan HK, Chen S, Zhang ZR. Detrimental or beneficial: Role of endothelial ENaC in vascular function. J Cell Physiol 2021; 237:29-48. [PMID: 34279047 DOI: 10.1002/jcp.30505] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 06/29/2021] [Accepted: 07/01/2021] [Indexed: 12/19/2022]
Abstract
In the past, it was believed that the expression of the epithelial sodium channel (ENaC) was restricted to epithelial tissues, such as the distal nephron, airway, sweat glands, and colon, where it is critical for sodium homeostasis. Over the past two decades, this paradigm has shifted due to the finding that ENaC is also expressed in various nonepithelial tissues, notably in vascular endothelial cells. In this review, the recent findings of the expression, regulation, and function of the endothelial ENaC (EnNaC) are discussed. The expression of EnNaC subunits is reported in a variety of endothelial cell lines and vasculatures, but this is controversial across different species and vessels and is not a universal finding in all vascular beds. The expression density of EnNaC is very faint compared to ENaC in the epithelium. To date, little is known about the regulatory mechanism of EnNaC. Through it can be regulated by aldosterone, the detailed downstream signaling remains elusive. EnNaC responds to increased extracellular sodium with the feedforward activation mechanism, which is quite different from the Na+ self-inhibition mechanism of ENaC. Functionally, EnNaC was shown to be a determinant of cellular mechanics and vascular tone as it can sense shear stress, and its activation or insertion into plasma membrane causes endothelial stiffness and reduced nitric oxide production. However, in some blood vessels, EnNaC is essential for maintaining the integrity of endothelial barrier function. In this context, we discuss the possible reasons for the distinct role of EnNaC in vasculatures.
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Affiliation(s)
- Jun Zhang
- School of Biomedical Sciences and Li Ka Shing Institute of Health Science, The Chinese University of Hong Kong, Hong Kong, China
| | - Hui-Kai Yuan
- Department of General Surgery, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Shuo Chen
- Department of Biopharmaceutical Sciences, School of Pharmacy, Harbin Medical University (Daqing), Daqing, China
| | - Zhi-Ren Zhang
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang Key Laboratory for Metabolic Disorder & Cancer Related Cardiovascular Diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
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80
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Abd El-Aziz TM, Soares AG, Mironova E, Boiko N, Kaur A, Archer CR, Stockand JD, Berman JM. Mechanisms and consequences of casein kinase II and ankyrin-3 regulation of the epithelial Na + channel. Sci Rep 2021; 11:14600. [PMID: 34272444 PMCID: PMC8285517 DOI: 10.1038/s41598-021-94118-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 07/01/2021] [Indexed: 01/21/2023] Open
Abstract
Activity of the Epithelial Na+ Channel (ENaC) in the distal nephron fine-tunes renal sodium excretion. Appropriate sodium excretion is a key factor in the regulation of blood pressure. Consequently, abnormalities in ENaC function can cause hypertension. Casein Kinase II (CKII) phosphorylates ENaC. The CKII phosphorylation site in ENaC resides within a canonical "anchor" ankyrin binding motif. CKII-dependent phosphorylation of ENaC is necessary and sufficient to increase channel activity and is thought to influence channel trafficking in a manner that increases activity. We test here the hypothesis that phosphorylation of ENaC by CKII within an anchor motif is necessary for ankyrin-3 (Ank-3) regulation of the channel, which is required for normal channel locale and function, and the proper regulation of renal sodium excretion. This was addressed using a fluorescence imaging strategy combining total internal reflection fluorescence (TIRF) microscopy with fluorescence recovery after photobleaching (FRAP) to quantify ENaC expression in the plasma membrane in living cells; and electrophysiology to quantify ENaC activity in split-open collecting ducts from principal cell-specific Ank-3 knockout mice. Sodium excretion studies also were performed in parallel in this knockout mouse. In addition, we substituted a key serine residue in the consensus CKII site in β-ENaC with alanine to abrogate phosphorylation and disrupt the anchor motif. Findings show that disrupting CKII signaling decreases ENaC activity by decreasing expression in the plasma membrane. In the principal cell-specific Ank-3 KO mouse, ENaC activity and sodium excretion were significantly decreased and increased, respectively. These results are consistent with CKII phosphorylation of ENaC functioning as a "switch" that favors Ank-3 binding to increase channel activity.
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Affiliation(s)
- Tarek Mohamed Abd El-Aziz
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center At San Antonio, San Antonio, TX, 78229-3900, USA
- Zoology Department, Faculty of Science, Minia University, El-Minia, 61519, Egypt
| | - Antonio G Soares
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center At San Antonio, San Antonio, TX, 78229-3900, USA
| | - Elena Mironova
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center At San Antonio, San Antonio, TX, 78229-3900, USA
| | - Nina Boiko
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center At San Antonio, San Antonio, TX, 78229-3900, USA
| | - Amanpreet Kaur
- Department of Biochemistry, University of Washington, Seattle, Washington, 98195, USA
| | - Crystal R Archer
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center At San Antonio, San Antonio, TX, 78229-3900, USA
| | - James D Stockand
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center At San Antonio, San Antonio, TX, 78229-3900, USA.
| | - Jonathan M Berman
- Department of Basic Science, New York Institute of Technology College of Osteopathic Medicine at Arkansas State University, Jonesboro, AR, 72401, USA
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81
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Harris A. Human molecular genetics and the long road to treating cystic fibrosis. Hum Mol Genet 2021; 30:R264-R273. [PMID: 34245257 DOI: 10.1093/hmg/ddab191] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/04/2021] [Accepted: 07/06/2021] [Indexed: 11/13/2022] Open
Abstract
The causative gene in cystic fibrosis was identified in 1989, three years before the publication of the first issue of Human Molecular Genetics. CFTR was among the first genes underlying a common inherited disorder to be cloned, and hence its subsequent utilization towards a cure for CF provides a roadmap for other monogenic diseases. Over the past 30 years the advances that built upon knowledge of the gene and the CFTR protein to develop effective therapeutics have been remarkable, and yet the setbacks have also been challenging. Technological progress in other fields has often circumvented the barriers. This review focuses on key aspects of CF diagnostics and current approaches to develop new therapies for all CFTR mutations. It also highlights the major research advances that underpinned progress towards treatments, and considers the remaining obstacles.
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Affiliation(s)
- Ann Harris
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA
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82
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Lactate sensing mechanisms in arterial chemoreceptor cells. Nat Commun 2021; 12:4166. [PMID: 34230483 PMCID: PMC8260783 DOI: 10.1038/s41467-021-24444-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 06/08/2021] [Indexed: 12/17/2022] Open
Abstract
Classically considered a by-product of anaerobic metabolism, lactate is now viewed as a fundamental fuel for oxidative phosphorylation in mitochondria, and preferred over glucose by many tissues. Lactate is also a signaling molecule of increasing medical relevance. Lactate levels in the blood can increase in both normal and pathophysiological conditions (e.g., hypoxia, physical exercise, or sepsis), however the manner by which these changes are sensed and induce adaptive responses is unknown. Here we show that the carotid body (CB) is essential for lactate homeostasis and that CB glomus cells, the main oxygen sensing arterial chemoreceptors, are also lactate sensors. Lactate is transported into glomus cells, leading to a rapid increase in the cytosolic NADH/NAD+ ratio. This in turn activates membrane cation channels, leading to cell depolarization, action potential firing, and Ca2+ influx. Lactate also decreases intracellular pH and increases mitochondrial reactive oxygen species production, which further activates glomus cells. Lactate and hypoxia, although sensed by separate mechanisms, share the same final signaling pathway and jointly activate glomus cells to potentiate compensatory cardiorespiratory reflexes. Lactate levels in blood change during hypoxia or exercise, however whether this variable is sensed to evoke adaptive responses is unknown. Here the authors show that oxygen-sensing carotid body cells stimulated by hypoxia are also activated by lactate to potentiate a compensatory ventilatory response.
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83
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Mareš Š, Filipovský J, Vlková K, Pešta M, Černá V, Hrabák J, Mlíková Seidlerová J, Mayer O. A novel nonsense mutation in the β-subunit of the epithelial sodium channel causing Liddle syndrome. Blood Press 2021; 30:291-299. [PMID: 34223773 DOI: 10.1080/08037051.2021.1942785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE Liddle syndrome is a hereditary form of arterial hypertension caused by mutations in the genes coding of the epithelial sodium channel - SCNN1A, SCNN1B and SCNN1G. It is characterised by early onset of hypertension and variable biochemical features such as hypokalaemia and low plasma concentrations of renin and aldosterone. Phenotypic variability is large and, therefore, LS is probably underdiagnosed. Our objective was to examine a family suspected from Liddle syndrome including genetic testing and evaluate clinical and biochemical features of affected family members. MATERIALS AND METHODS Thirteen probands from the Czech family, related by blood, underwent physical examination, laboratory tests, and genetic testing. Alleles of SCNN1B and SCNN1G genes were examined by PCR amplification and Sanger sequencing of amplicons. RESULTS We identified a novel mutation in the β-subunit of an epithelial sodium channel coded by the SCNN1B gene, causing the nonsense mutation in the protein sequence p.Tyr604*. This mutation was detected in 7 members of the family. The mutation carriers differed in the severity of hypertension and hypokalaemia which appeared only after diuretics in most of them; low aldosterone level (< 0.12 nmol/l) was, however, present in all. CONCLUSIONS This finding expands the spectrum of known mutations causing Liddle syndrome. Hypoaldosteronemia was 100% sensitive sign in the mutation carriers. Low levels are observed especially in the Caucasian population reaching 96% sensitivity. Assessment of plasma aldosterone concentration is helpful for differential diagnosis of arterial hypertension. CONDENSED ABSTRACT Liddle syndrome is a hereditary form of arterial hypertension caused by mutations in the genes encoding the epithelial sodium channel's α-, β- and γ-subunit. It is usually manifested by early onset of hypertension accompanied by low potassium and aldosterone levels. We performed a physical examination, laboratory tests and genetic screening in 13 members of a Czech family. We found a new mutation of the SCNN1B gene which encodes the β-subunit of the epithelial sodium channel. We describe the variability of each family member phenotype and point out the relevance of using aldosterone levels as a high sensitivity marker of Liddle syndrome in Caucasians.
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Affiliation(s)
- Štěpán Mareš
- Second Department of Internal Medicine, University Hospital, Pilsen, Czech Republic.,Biomedical Center, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic
| | - Jan Filipovský
- Second Department of Internal Medicine, University Hospital, Pilsen, Czech Republic.,Biomedical Center, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic
| | - Kateřina Vlková
- Biomedical Center, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic.,Department of Microbiology, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic
| | - Martin Pešta
- Biomedical Center, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic.,Institute of Biology, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic
| | - Václava Černá
- Institute of Biology, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic
| | - Jaroslav Hrabák
- Biomedical Center, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic.,Department of Microbiology, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic
| | - Jitka Mlíková Seidlerová
- Second Department of Internal Medicine, University Hospital, Pilsen, Czech Republic.,Biomedical Center, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic
| | - Otto Mayer
- Second Department of Internal Medicine, University Hospital, Pilsen, Czech Republic.,Biomedical Center, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic
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84
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Morris C, O'Donnell MJ. Vacuolar H+-ATPase and Na+/K+-ATPase energize Na+ uptake mechanisms in the nuchal organ of the hyperregulating freshwater crustacean Daphnia magna. J Exp Biol 2021; 224:269112. [PMID: 34115859 DOI: 10.1242/jeb.242205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 05/06/2021] [Indexed: 11/20/2022]
Abstract
The nuchal organ of the embryos and neonates of the cladoceran, Daphnia magna, has been shown to be a site of Na+ influx and H+, NH4+ and Cl- efflux. This study combines the scanning ion-selective electrode technique with application of inhibitors of specific transporters to assess the mechanisms of Na+ transport across the nuchal organ. Na+ influx across the nuchal organ was inhibited both by inhibitors of the Na+/K+-ATPase (ouabain, bufalin) and by inhibitors of the vacuolar H+-ATPase (bafilomycin, N-ethylmaleimde, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, KM91104, S-nitrosoglutathione). Na+ influx was unaffected by the epithelial Na+ channel blocker benzamil, but was sensitive to ethylisopropyl amiloride and elevated external ammonium concentrations, consistent with roles for Na+/H+ and Na+/NH4+ exchangers in the apical membrane but not Na+ channels. Transport across the basolateral membrane into the haemolymph is proposed to involve the Na+/K+-ATPase and a thiazide-sensitive Na+/Cl- cotransporter.
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Affiliation(s)
- Carolyn Morris
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
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85
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Raghav PK, Kalyanaraman K, Kumar D. Human cell receptors: potential drug targets to combat COVID-19. Amino Acids 2021; 53:813-842. [PMID: 33950300 PMCID: PMC8097256 DOI: 10.1007/s00726-021-02991-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 04/21/2021] [Indexed: 01/08/2023]
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the coronavirus disease 2019 (COVID-19). The World Health Organization (WHO) has announced that COVID-19 is a pandemic having a higher spread rate rather than the mortality. Identification of a potential approach or therapy against COVID-19 is still under consideration. Therefore, it is essential to have an insight into SARS-CoV-2, its interacting partner, and domains for an effective treatment. The present study is divided into three main categories, including SARS-CoV-2 prominent receptor and its expression levels, other interacting partners, and their binding domains. The first section focuses primarily on coronaviruses' general aspects (SARS-CoV-2, SARS-CoV, and the Middle East Respiratory Syndrome Coronaviruses (MERS-CoV)) their structures, similarities, and mode of infections. The second section discusses the host receptors which includes the human targets of coronaviruses like dipeptidyl peptidase 4 (DPP4), CD147, CD209L, Angiotensin-Converting Enzyme 2 (ACE2), and other miscellaneous targets (type-II transmembrane serine proteases (TTSPs), furin, trypsin, cathepsins, thermolysin, elastase, phosphatidylinositol 3-phosphate 5-kinase, two-pore segment channel, and epithelium sodium channel C-α subunit). The human cell receptor, ACE2 plays an essential role in the Renin-Angiotensin system (RAS) pathway and COVID-19. Thus, this section also discusses the ACE2 expression and risk of COVID-19 infectivity in various organs and tissues such as the liver, lungs, intestine, heart, and reproductive system in the human body. Absence of ACE2 protein expression in immune cells could be used for limiting the SARS-CoV-2 infection. The third section covers the current available approaches for COVID-19 treatment. Overall, this review focuses on the critical role of human cell receptors involved in coronavirus pathogenesis, which would likely be used in designing target-specific drugs to combat COVID-19.
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Affiliation(s)
| | - Keerthana Kalyanaraman
- Amity Institute of Biotechnology, Amity University, Sector-125, Noida, Uttar Pradesh, India
| | - Dinesh Kumar
- ICMR-National Institute of Cancer Prevention & Research, Noida, 201301, India.
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86
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Abstract
The Epithelial Na+ Channel, ENaC, comprised of 3 subunits (αβγ, or sometimes δβγENaC), plays a critical role in regulating salt and fluid homeostasis in the body. It regulates fluid reabsorption into the blood stream from the kidney to control blood volume and pressure, fluid absorption in the lung to control alveolar fluid clearance at birth and maintenance of normal airway surface liquid throughout life, and fluid absorption in the distal colon and other epithelial tissues. Moreover, recent studies have also revealed a role for sodium movement via ENaC in nonepithelial cells/tissues, such as endothelial cells in blood vessels and neurons. Over the past 25 years, major advances have been made in our understanding of ENaC structure, function, regulation, and role in human disease. These include the recently solved three-dimensional structure of ENaC, ENaC function in various tissues, and mutations in ENaC that cause a hereditary form of hypertension (Liddle syndrome), salt-wasting hypotension (PHA1), or polymorphism in ENaC that contributes to other diseases (such as cystic fibrosis). Moreover, great strides have been made in deciphering the regulation of ENaC by hormones (e.g., the mineralocorticoid aldosterone, glucocorticoids, vasopressin), ions (e.g., Na+ ), proteins (e.g., the ubiquitin-protein ligase NEDD4-2, the kinases SGK1, AKT, AMPK, WNKs & mTORC2, and proteases), and posttranslational modifications [e.g., (de)ubiquitylation, glycosylation, phosphorylation, acetylation, palmitoylation]. Characterization of ENaC structure, function, regulation, and role in human disease, including using animal models, are described in this article, with a special emphasis on recent advances in the field. © 2021 American Physiological Society. Compr Physiol 11:1-29, 2021.
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Affiliation(s)
- Daniela Rotin
- The Hospital for Sick Children, and The University of Toronto, Toronto, Canada
| | - Olivier Staub
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
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87
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Wang QS, Liang C, Jiang S, Zhu D, Sun Y, Niu N, Yang X, Yang YC, Dong BH, Yao J, Yu CJ, Lou J, Tang LL, Wu MM, Zhang ZR, Ma HP. NaHS or Lovastatin Attenuates Cyclosporine A-Induced Hypertension in Rats by Inhibiting Epithelial Sodium Channels. Front Pharmacol 2021; 12:665111. [PMID: 34122084 PMCID: PMC8187945 DOI: 10.3389/fphar.2021.665111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 04/19/2021] [Indexed: 12/01/2022] Open
Abstract
The use of cyclosporine A (CsA) in transplant recipients is limited due to its side effects of causing severe hypertension. We have previously shown that CsA increases the activity of the epithelial sodium channel (ENaC) in cultured distal nephron cells. However, it remains unknown whether ENaC mediates CsA-induced hypertension and how we could prevent hypertension. Our data show that the open probability of ENaC in principal cells of split-open cortical collecting ducts was significantly increased after treatment of rats with CsA; the increase was attenuated by lovastatin. Moreover, CsA also elevated the levels of intracellular cholesterol (Cho), intracellular reactive oxygen species (ROS) via activation of NADPH oxidase p47phox, serum- and glucocorticoid-induced kinase isoform 1 (Sgk1), and phosphorylated neural precursor cell-expressed developmentally downregulated protein 4-2 (p-Nedd4-2) in the kidney cortex. Lovastatin also abolished CsA-induced elevation of α-, ß-, and γ-ENaC expressions. CsA elevated systolic blood pressure in rats; the elevation was completely reversed by lovastatin (an inhibitor of cholesterol synthesis), NaHS (a donor of H2S which ameliorated CsA-induced elevation of reactive oxygen species), or amiloride (a potent ENaC blocker). These results suggest that CsA elevates blood pressure by increasing ENaC activity via a signaling cascade associated with elevation of intracellular ROS, activation of Sgk1, and inactivation of Nedd4-2 in an intracellular cholesterol-dependent manner. Our data also show that NaHS ameliorates CsA-induced hypertension by inhibition of oxidative stress.
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Affiliation(s)
- Qiu-Shi Wang
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Chen Liang
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Shuai Jiang
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Di Zhu
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Yu Sun
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Na Niu
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Xu Yang
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Yan-Chao Yang
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Bi-Han Dong
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Jie Yao
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Chang-Jiang Yu
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Jie Lou
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Liang-Liang Tang
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Ming-Ming Wu
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Zhi-Ren Zhang
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder & cancer related cardiovascular diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - He-Ping Ma
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
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88
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Lossow K, Hermans-Borgmeyer I, Meyerhof W, Behrens M. Segregated Expression of ENaC Subunits in Taste Cells. Chem Senses 2021; 45:235-248. [PMID: 32006019 DOI: 10.1093/chemse/bjaa004] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Salt taste is one of the 5 basic taste qualities. Depending on the concentration, table salt is perceived either as appetitive or aversive, suggesting the contribution of several mechanisms to salt taste, distinguishable by their sensitivity to the epithelial sodium channel (ENaC) blocker amiloride. A taste-specific knockout of the α-subunit of the ENaC revealed the relevance of this polypeptide for low-salt transduction, whereas the response to other taste qualities remained normal. The fully functional ENaC is composed of α-, β-, and γ-subunits. In taste tissue, however, the precise constitution of the channel and the cell population responsible for detecting table salt remain uncertain. In order to examine the cells and subunits building the ENaC, we generated mice carrying modified alleles allowing the synthesis of green and red fluorescent proteins in cells expressing the α- and β-subunit, respectively. Fluorescence signals were detected in all types of taste papillae and in taste buds of the soft palate and naso-incisor duct. However, the lingual expression patterns of the reporters differed depending on tongue topography. Additionally, immunohistochemistry for the γ-subunit of the ENaC revealed a lack of overlap between all potential subunits. The data suggest that amiloride-sensitive recognition of table salt is unlikely to depend on the classical ENaCs formed by α-, β-, and γ-subunits and ask for a careful investigation of the channel composition.
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Affiliation(s)
- Kristina Lossow
- Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee, Nuthetal, Germany
| | - Irm Hermans-Borgmeyer
- Transgenic Animal Unit, University Medical Center Hamburg-Eppendorf (ZMNH), Hamburg, Germany
| | - Wolfgang Meyerhof
- Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee, Nuthetal, Germany
| | - Maik Behrens
- Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee, Nuthetal, Germany
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89
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Abstract
Among the 5 taste qualities, salt is the least understood. The receptors, their expression pattern in taste cells, and the transduction mechanisms for salt taste are still unclear. Previous studies have suggested that low concentrations of NaCl are detected by the amiloride-sensitive epithelial Na+ channel (ENaC), which in other systems requires assembly of 3 homologous subunits (α, β, and γ) to form a functional channel. However, a new study from Lossow and colleagues, published in this issue of Chemical Senses, challenges that hypothesis by examining expression levels of the 3 ENaC subunits in individual taste cells using gene-targeted mice in combination with immunohistochemistry and in situ hybridization. Results show a lack of colocalization of ENaC subunits in taste cells as well as expression of subunits in taste cells that show no amiloride sensitivity. These new results question the molecular identity of the amiloride-sensitive Na+ conductance in taste cells.
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Affiliation(s)
- Aurelie Vandenbeuch
- Department of Otolaryngology and Rocky Mountain Taste and Smell Center, University of Colorado-Anschutz Medical Campus, Aurora, USA
| | - Sue C Kinnamon
- Department of Otolaryngology and Rocky Mountain Taste and Smell Center, University of Colorado-Anschutz Medical Campus, Aurora, USA
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90
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Xu BY, Jin Y, Ma XH, Wang CY, Guo Y, Zhou D. The potential role of mechanically sensitive ion channels in the physiology, injury, and repair of articular cartilage. J Orthop Surg (Hong Kong) 2021; 28:2309499020950262. [PMID: 32840428 DOI: 10.1177/2309499020950262] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Biomechanical factors play an extremely important role in regulating the function of articular chondrocytes. Understanding the mechanical factors that drive chondrocyte biological responses is at the heart of our interpretation of cascade events leading to changes in articular cartilage osteoarthritis. The mechanism by which mechanical load is transduced into intracellular signals that can regulate chondrocyte gene expression remains largely unknown. The mechanically sensitive ion channel (MSC) may be one of its specific mechanisms. This review focuses on four ion channels involved in the mechanotransduction of chondrocytes, exploring their properties and the main factors that activate the associated pathways. The upstream and downstream potential relationships between the protein pathways were also explored. The specific biophysical mechanism of the chondrocyte mechanical microenvironment is becoming the focus of research. Elucidating the mechanotransduction mechanism of MSC is essential for the research of biophysical pathogenesis and targeted drugs in cartilage injury-related diseases.
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Affiliation(s)
- Bo-Yang Xu
- School of Acupuncture-Moxibustion and Tuina, 58301Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China
| | - Yu Jin
- School of Chinese Medicine, 58301Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China
| | - Xiao-Hui Ma
- School of Culture and Health Communication, 58301Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China
| | - Chi-Yu Wang
- Department of Electrical Engineering and Computer Sciences, 1438University of California, Berkeley, CA, USA
| | - Yi Guo
- School of Chinese Medicine, 58301Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China.,Research Center of Experimental Acupuncture Science, 58301Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China.,National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, People's Republic of China
| | - Dan Zhou
- School of Acupuncture-Moxibustion and Tuina, 58301Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China.,Research Center of Experimental Acupuncture Science, 58301Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China.,National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, People's Republic of China
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91
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Puri S, Lee Y. Salt Sensation and Regulation. Metabolites 2021; 11:metabo11030175. [PMID: 33802977 PMCID: PMC8002656 DOI: 10.3390/metabo11030175] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/08/2021] [Accepted: 03/15/2021] [Indexed: 12/02/2022] Open
Abstract
Taste sensation and regulation are highly conserved in insects and mammals. Research conducted over recent decades has yielded major advances in our understanding of the molecular mechanisms underlying the taste sensors for a variety of taste sensations and the processes underlying regulation of ingestion depending on our internal state. Salt (NaCl) is an essential ingested nutrient. The regulation of internal sodium concentrations for physiological processes, including neuronal activity, fluid volume, acid–base balance, and muscle contraction, are extremely important issues in animal health. Both mammals and flies detect low and high NaCl concentrations as attractive and aversive tastants, respectively. These attractive or aversive behaviors can be modulated by the internal nutrient state. However, the differential encoding of the tastes underlying low and high salt concentrations in the brain remain unclear. In this review, we discuss the current view of taste sensation and modulation in the brain with an emphasis on recent advances in this field. This work presents new questions that include but are not limited to, “How do the fly’s neuronal circuits process this complex salt code?” and “Why do high concentrations of salt induce a negative valence only when the need for salt is low?” A better understanding of regulation of salt homeostasis could improve our understanding of why our brains enjoy salty food so much.
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Affiliation(s)
- Sonali Puri
- Interdisciplinary Program for Bio-Health Convergence, Kookmin University, Seoul 02707, Korea;
| | - Youngseok Lee
- Interdisciplinary Program for Bio-Health Convergence, Kookmin University, Seoul 02707, Korea;
- Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul 02707, Korea
- Correspondence: ; Tel.: +82-2-910-5734
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92
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Fechner S, D'Alessandro I, Wang L, Tower C, Tao L, Goodman MB. DEG/ENaC/ASIC channels vary in their sensitivity to anti-hypertensive and non-steroidal anti-inflammatory drugs. J Gen Physiol 2021; 153:211847. [PMID: 33656557 PMCID: PMC7933985 DOI: 10.1085/jgp.202012655] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 01/12/2021] [Indexed: 12/19/2022] Open
Abstract
The degenerin channels, epithelial sodium channels, and acid-sensing ion channels (DEG/ENaC/ASICs) play important roles in sensing mechanical stimuli, regulating salt homeostasis, and responding to acidification in the nervous system. They have two transmembrane domains separated by a large extracellular domain and are believed to assemble as homomeric or heteromeric trimers. Based on studies of selected family members, these channels are assumed to form nonvoltage-gated and sodium-selective channels sensitive to the anti-hypertensive drug amiloride. They are also emerging as a target of nonsteroidal anti-inflammatory drugs (NSAIDs). Caenorhabditis elegans has more than two dozen genes encoding DEG/ENaC/ASIC subunits, providing an excellent opportunity to examine variations in drug sensitivity. Here, we analyze a subset of the C. elegans DEG/ENaC/ASIC proteins to test the hypothesis that individual family members vary not only in their ability to form homomeric channels but also in their drug sensitivity. We selected a panel of C. elegans DEG/ENaC/ASICs that are coexpressed in mechanosensory neurons and expressed gain-of-function or d mutants in Xenopus laevis oocytes. We found that only DEGT‑1d, UNC‑8d, and MEC‑4d formed homomeric channels and that, unlike MEC‑4d and UNC‑8d, DEGT‑1d channels were insensitive to amiloride and its analogues. As reported for rat ASIC1a, NSAIDs inhibit DEGT‑1d and UNC‑8d channels. Unexpectedly, MEC‑4d was strongly potentiated by NSAIDs, an effect that was decreased by mutations in the putative NSAID-binding site in the extracellular domain. Collectively, these findings reveal that not all DEG/ENaC/ASIC channels are amiloride-sensitive and that NSAIDs can both inhibit and potentiate these channels.
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Affiliation(s)
- Sylvia Fechner
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
| | - Isabel D'Alessandro
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
| | - Lingxin Wang
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
| | - Calvin Tower
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
| | - Li Tao
- Department of Biology, Stanford University, Stanford, CA
| | - Miriam B Goodman
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
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93
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CRISPR/Cas9 Mediated Knock Down of δ-ENaC Blunted the TNF-Induced Activation of ENaC in A549 Cells. Int J Mol Sci 2021; 22:ijms22041858. [PMID: 33673381 PMCID: PMC7917654 DOI: 10.3390/ijms22041858] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 02/02/2021] [Accepted: 02/09/2021] [Indexed: 11/16/2022] Open
Abstract
Tumor necrosis factor (TNF) is known to activate the epithelial Na+ channel (ENaC) in A549 cells. A549 cells are widely used model for ENaC research. The role of δ-ENaC subunit in TNF-induced activation has not been studied. In this study we hypothesized that δ-ENaC plays a major role in TNF-induced activation of ENaC channel in A549 cells which are widely used model for ENaC research. We used CRISPR/Cas 9 approach to knock down (KD) the δ-ENaC in A549 cells. Western blot and immunofluorescence assays were performed to analyze efficacy of δ-ENaC protein KD. Whole-cell patch clamp technique was used to analyze the TNF-induced activation of ENaC. Overexpression of wild type δ-ENaC in the δ-ENaC KD of A549 cells restored the TNF-induced activation of whole-cell Na+ current. Neither N-linked glycosylation sites nor carboxyl terminus domain of δ-ENaC was necessary for the TNF-induced activation of whole-cell Na+ current in δ-ENaC KD of A549 cells. Our data demonstrated that in A549 cells the δ-ENaC plays a major role in TNF-induced activation of ENaC.
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94
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Liu G, Fu D, Tian H, Dai A. The mechanism of ions in pulmonary hypertension. Pulm Circ 2021; 11:2045894020987948. [PMID: 33614016 PMCID: PMC7869166 DOI: 10.1177/2045894020987948] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 12/23/2020] [Indexed: 12/15/2022] Open
Abstract
Pulmonary hypertension(PH)is a kind of hemodynamic and pathophysiological state, in which the pulmonary artery pressure (PAP) rises above a certain threshold. The main pathological manifestation is pulmonary vasoconstriction and remodelling progressively. More and more studies have found that ions play a major role in the pathogenesis of PH. Many vasoactive substances, inflammatory mediators, transcription-inducing factors, apoptosis mediators, redox substances and translation modifiers can control the concentration of ions inside and outside the cell by regulating the activity of ion channels, which can regulate vascular contraction, cell proliferation, migration, apoptosis, inflammation and other functions. We all know that there are no effective drugs to treat PH. Ions are involved in the occurrence and development of PH, so it is necessary to clarify the mechanism of ions in PH as a therapeutic target for PH. The main ions involved in PH are calcium ion (Ca2+), potassium ion (K+), sodium ion (Na+) and chloride ion (Cl-). Here, we mainly discuss the distribution of these ions and their channels in pulmonary arteries and their role in the pathogenesis of PH.
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Affiliation(s)
- Guogu Liu
- Department of Graduate School, University of South China,
Hengyang, China
- Department of Respiratory Medicine, Hunan Provincial People’s
Hospital, Changsha, China
| | - Daiyan Fu
- Department of Respiratory Medicine, Hunan Provincial People’s
Hospital, Changsha, China
| | - Heshen Tian
- Department of Graduate School, University of South China,
Hengyang, China
- Department of Respiratory Medicine, Hunan Provincial People’s
Hospital, Changsha, China
| | - Aiguo Dai
- Department of Respiratory Diseases, Hunan University of Chinese
Medicine, Changsha, China
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95
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Brower RK, Ghlichloo IA, Shabgahi V, Elsholz D, Menon RK, Vyas AK. Liddle Syndrome due to a Novel c.1713 Deletion in the Epithelial Sodium Channel β-Subunit in a Normotensive Adolescent. AACE Clin Case Rep 2020; 7:65-68. [PMID: 33851023 PMCID: PMC7924163 DOI: 10.1016/j.aace.2020.11.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Objective Liddle syndrome (LS) is a rare autosomal dominant condition secondary to a gain-of-function mutation affecting the epithelial sodium channels (ENaCs) in the distal nephron. It presents with early-onset hypertension, hypokalemia, and metabolic alkalosis in the face of hyporeninemia and hypoaldosteronism. We report a novel mutation affecting the ENaCs in a normotensive adolescent with LS. Methods We describe a pediatric case of LS with a novel mutation and review the condition’s presentation and management. To date, 31 different mutations in the β- or γ-subunit of ENaCs have been reported as associated with LS. Results We describe a 16-year-old girl presenting with muscle cramps with a strong family history of hypertension and hypokalemia. Initial investigations revealed hypokalemia together with hypoaldosteronism and hyporeninemia. Subsequent genetic testing revealed a novel mutation in SCNN1B (deletion: c.1713delC), leading to the premature termination of the sodium channel epithelial 1 subunit-β protein and the LS phenotype. Treatment with triamterene (50 mg, twice daily) and potassium chloride (20 mEq, once daily) normalized the serum potassium and led to resolution of her muscle cramps. Conclusion It is essential to consider investigating the presence of rare genetic syndromes, like LS, when a patient presents with hypokalemia. Further studies are needed to understand the variable presentation of this condition.
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Affiliation(s)
- Raven K. Brower
- College of Medicine, California Northstate University, Elk Grove, California
| | - Ida A. Ghlichloo
- College of Medicine, California Northstate University, Elk Grove, California
| | - Venus Shabgahi
- College of Medicine, California Northstate University, Elk Grove, California
| | | | - Ram K. Menon
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan
| | - Arpita K. Vyas
- College of Medicine, California Northstate University, Elk Grove, California
- Address correspondence and reprint requests to Dr Arpita K Vyas, Elk Grove, CA 95757.
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96
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Paudel P, McDonald FJ, Fronius M. The δ subunit of epithelial sodium channel in humans-a potential player in vascular physiology. Am J Physiol Heart Circ Physiol 2020; 320:H487-H493. [PMID: 33275523 DOI: 10.1152/ajpheart.00800.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vascular epithelial sodium channels (ENaCs) made up of canonical α, β, and γ subunits have attracted more attention recently owing to their physiological role in vascular health and disease. A fourth subunit, δ-ENaC, is expressed in various mammalian species, except mice and rats, which are common animal models for cardiovascular research. Accordingly, δ-ENaC is the least understood subunit. However, the recent discovery of δ subunit in human vascular cells indicates that this subunit may play a significant role in normal/pathological vascular physiology in humans. Channels containing the δ subunit have different biophysical and pharmacological properties compared with channels containing the α subunit, with the potential to alter the vascular function of ENaC in health and disease. Hence, it is important to investigate the expression and function of δ-ENaC in the vasculature to identify whether δ-ENaC is a potential new drug target for the treatment of cardiovascular disease. In this review, we will focus on the existing knowledge of δ-ENaC and implications for vascular physiology and pathophysiology in humans.
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Affiliation(s)
- Puja Paudel
- Department of Physiology, University of Otago, Dunedin, New Zealand.,HeartOtago, University of Otago, Dunedin, New Zealand
| | - Fiona J McDonald
- Department of Physiology, University of Otago, Dunedin, New Zealand
| | - Martin Fronius
- Department of Physiology, University of Otago, Dunedin, New Zealand.,HeartOtago, University of Otago, Dunedin, New Zealand
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97
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Mukherjee A, MacDonald KD, Kim J, Henderson MI, Eygeris Y, Sahay G. Engineered mutant α-ENaC subunit mRNA delivered by lipid nanoparticles reduces amiloride currents in cystic fibrosis-based cell and mice models. SCIENCE ADVANCES 2020; 6:6/47/eabc5911. [PMID: 33208364 PMCID: PMC7673816 DOI: 10.1126/sciadv.abc5911] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 10/05/2020] [Indexed: 05/02/2023]
Abstract
Cystic fibrosis (CF) results from mutations in the chloride-conducting CF transmembrane conductance regulator (CFTR) gene. Airway dehydration and impaired mucociliary clearance in CF is proposed to result in tonic epithelial sodium channel (ENaC) activity, which drives amiloride-sensitive electrogenic sodium absorption. Decreasing sodium absorption by inhibiting ENaC can reverse airway surface liquid dehydration. Here, we inhibit endogenous heterotrimeric ENaC channels by introducing inactivating mutant ENaC α mRNA (αmutENaC). Lipid nanoparticles carrying αmutENaC were transfected in CF-based airway cells in vitro and in vivo. We observed a significant decrease in macroscopic as well as amiloride-sensitive ENaC currents and an increase in airway surface liquid height in CF airway cells. Similarly, intranasal transfection of αmutENaC mRNA decreased amiloride-sensitive nasal potential difference in CFTRKO mice. These data suggest that mRNA-based ENaC inhibition is a powerful strategy for reducing mucus dehydration and has therapeutic potential for treating CF in all patients, independent of genotype.
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Affiliation(s)
- Anindit Mukherjee
- Department of Pharmaceutical Sciences, College of Pharmacy, Robertson Life Sciences Building, Oregon State University, Portland, OR 97201, USA
| | - Kelvin D MacDonald
- Department of Pharmaceutical Sciences, College of Pharmacy, Robertson Life Sciences Building, Oregon State University, Portland, OR 97201, USA
- Department of Pediatrics, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Jeonghwan Kim
- Department of Pharmaceutical Sciences, College of Pharmacy, Robertson Life Sciences Building, Oregon State University, Portland, OR 97201, USA
| | - Michael I Henderson
- Department of Cell, Developmental and Cancer Biology, Oregon Health & Science University, Portland, OR 97201, USA
| | - Yulia Eygeris
- Department of Pharmaceutical Sciences, College of Pharmacy, Robertson Life Sciences Building, Oregon State University, Portland, OR 97201, USA
| | - Gaurav Sahay
- Department of Pharmaceutical Sciences, College of Pharmacy, Robertson Life Sciences Building, Oregon State University, Portland, OR 97201, USA.
- Department of Biomedical Engineering, Robertson Life Sciences Building, Oregon Health & Science University, Portland, OR 97239, USA
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98
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Cheung TT, Geda AC, Ware AW, Rasulov SR, Tenci P, Hamilton KL, McDonald FJ. Retromer is involved in epithelial Na+ channel trafficking. Am J Physiol Renal Physiol 2020; 319:F895-F907. [DOI: 10.1152/ajprenal.00198.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The epithelial Na+ channel (ENaC) located at the apical membrane in many epithelia is the rate-limiting step for Na+ reabsorption. Tight regulation of the plasma membrane population of ENaC is required, as hypertension or hypotension may result if too many or too few ENaCs are present. Endocytosed ENaC travels to the early endosome and is then either trafficked to the lysosome for degradation or recycled back to the plasma membrane. Recently, the retromer recycling complex, located at the early endosome, has been implicated in plasma membrane protein recycling pathways. We hypothesized that the retromer is required for recycling of ENaC. Stabilization of retromer function with the retromer stabilizing chaperone R55 increased ENaC current, whereas knockdown or overexpression of individual retromer and associated proteins altered ENaC current and cell surface population of ENaC. KIBRA was identified as an ENaC-binding protein allowing ENaC to link to sorting nexin 4 to alter ENaC trafficking. Knockdown of the retromer-associated cargo-binding sorting nexin 27 protein did not alter ENaC current, whereas CCDC22, a CCC-complex protein, coimmunoprecipitated with ENaC, and CCDC22 knockdown decreased ENaC current and population at the cell surface. Together, our results confirm that retromer and the CCC complex play a role in recycling of ENaC to the plasma membrane.
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Affiliation(s)
- Tanya T. Cheung
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Anna C. Geda
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Adam W. Ware
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Sahib R. Rasulov
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Polly Tenci
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Kirk L. Hamilton
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Fiona J. McDonald
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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99
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Gentzsch M, Rossier BC. A Pathophysiological Model for COVID-19: Critical Importance of Transepithelial Sodium Transport upon Airway Infection. FUNCTION 2020; 1:zqaa024. [PMID: 33201937 PMCID: PMC7662147 DOI: 10.1093/function/zqaa024] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 09/29/2020] [Accepted: 10/03/2020] [Indexed: 01/06/2023] Open
Abstract
The Coronavirus Disease 2019 (COVID-19) pandemic remains a serious public health problem and will continue to be until effective drugs and/or vaccines are available. The rational development of drugs critically depends on our understanding of disease mechanisms, that is, the physiology and pathophysiology underlying the function of the organ targeted by the virus. Since the beginning of the pandemic, tireless efforts around the globe have led to numerous publications on the virus, its receptor, its entry into the cell, its cytopathic effects, and how it triggers innate and native immunity but the role of apical sodium transport mediated by the epithelial sodium channel (ENaC) during the early phases of the infection in the airways has received little attention. We propose a pathophysiological model that defines the possible role of ENaC in this process.
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Affiliation(s)
- Martina Gentzsch
- Department of Cell Biology and Physiology, Marsico Lung Institute, University of North Carolina, Chapel Hill, USA
- Department of Pediatric Pulmonology, Marsico Lung Institute, University of North Carolina, Chapel Hill, USA
| | - Bernard C Rossier
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
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100
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Bazard P, Ding B, Chittam HK, Zhu X, Parks TA, Taylor-Clark TE, Bhethanabotla VR, Frisina RD, Walton JP. Aldosterone up-regulates voltage-gated potassium currents and NKCC1 protein membrane fractions. Sci Rep 2020; 10:15604. [PMID: 32973172 PMCID: PMC7515911 DOI: 10.1038/s41598-020-72450-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 07/12/2020] [Indexed: 02/02/2023] Open
Abstract
Na+-K+-2Cl- Cotransporter (NKCC1) is a protein that aids in the active transport of sodium, potassium, and chloride ions across cell membranes. It has been shown that long-term systemic treatment with aldosterone (ALD) can enhance NKCC1 protein expression and activity in the aging cochlea resulting in improved hearing. In the present work, we used a cell line with confirmed NKCC1 expression to demonstrate that in vitro application of ALD increased outward voltage-gated potassium currents significantly, and simultaneously upregulated whole lysate and membrane portion NKCC1 protein expression. These ALD-induced changes were blocked by applying the mineralocorticoid receptor antagonist eplerenone. However, application of the NKCC1 inhibitor bumetanide or the potassium channel antagonist Tetraethyl ammonium had no effect. In addition, NKKC1 mRNA levels remained stable, indicating that ALD modulates NKCC1 protein expression via the activation of mineralocorticoid receptors and post-transcriptional modifications. Further, in vitro electrophysiology experiments, with ALD in the presence of NKCC1, K+ channel and mineralocorticoid receptor inhibitors, revealed interactions between NKCC1 and outward K+ channels, mediated by a mineralocorticoid receptor-ALD complex. These results provide evidence of the therapeutic potential of ALD for the prevention/treatment of inner ear disorders such as age-related hearing loss.
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Affiliation(s)
- Parveen Bazard
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL, 33620, USA
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL, 33612, USA
| | - Bo Ding
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL, 33620, USA
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL, 33612, USA
| | - Harish K Chittam
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL, 33620, USA
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL, 33612, USA
| | - Xiaoxia Zhu
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL, 33620, USA
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL, 33612, USA
| | - Thomas A Parks
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, FL, 33620, USA
| | - Thomas E Taylor-Clark
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, FL, 33620, USA
| | - Venkat R Bhethanabotla
- Department of Chemical Engineering, College of Engineering, University of South Florida, Tampa, FL, 33620, USA
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL, 33612, USA
| | - Robert D Frisina
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL, 33620, USA
- Department Communication Sciences and Disorders, College of Behavioral and Communication Sciences, Tampa, FL, 33620, USA
- Department of Chemical Engineering, College of Engineering, University of South Florida, Tampa, FL, 33620, USA
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL, 33612, USA
| | - Joseph P Walton
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL, 33620, USA.
- Department Communication Sciences and Disorders, College of Behavioral and Communication Sciences, Tampa, FL, 33620, USA.
- Department of Chemical Engineering, College of Engineering, University of South Florida, Tampa, FL, 33620, USA.
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL, 33612, USA.
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