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Sure F, Einsiedel J, Gmeiner P, Duchstein P, Zahn D, Korbmacher C, Ilyaskin AV. The small molecule activator S3969 stimulates the epithelial sodium channel by interacting with a specific binding pocket in the channel's β-subunit. J Biol Chem 2024; 300:105785. [PMID: 38401845 PMCID: PMC11065748 DOI: 10.1016/j.jbc.2024.105785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 01/13/2024] [Accepted: 02/19/2024] [Indexed: 02/26/2024] Open
Abstract
The epithelial sodium channel (ENaC) is essential for mediating sodium absorption in several epithelia. Its impaired function leads to severe disorders, including pseudohypoaldosteronism type 1 and respiratory distress. Therefore, pharmacological ENaC activators have potential therapeutic implications. Previously, a small molecule ENaC activator (S3969) was developed. So far, little is known about molecular mechanisms involved in S3969-mediated ENaC stimulation. Here, we identified an S3969-binding site in human ENaC by combining structure-based simulations with molecular biological methods and electrophysiological measurements of ENaC heterologously expressed in Xenopus laevis oocytes. We confirmed a previous observation that the extracellular loop of β-ENaC is essential for ENaC stimulation by S3969. Molecular dynamics simulations predicted critical residues in the thumb domain of β-ENaC (Arg388, Phe391, and Tyr406) that coordinate S3969 within a binding site localized at the β-γ-subunit interface. Importantly, mutating each of these residues reduced (R388H; R388A) or nearly abolished (F391G; Y406A) the S3969-mediated ENaC activation. Molecular dynamics simulations also suggested that S3969-mediated ENaC stimulation involved a movement of the α5 helix of the thumb domain of β-ENaC away from the palm domain of γ-ENaC. Consistent with this, the introduction of two cysteine residues (βR437C - γS298C) to form a disulfide bridge connecting these two domains prevented ENaC stimulation by S3969 unless the disulfide bond was reduced by DTT. Finally, we demonstrated that S3969 stimulated ENaC endogenously expressed in cultured human airway epithelial cells (H441). These new findings may lead to novel (patho-)physiological and therapeutic concepts for disorders associated with altered ENaC function.
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Affiliation(s)
- Florian Sure
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jürgen Einsiedel
- Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Patrick Duchstein
- Theoretical Chemistry/Computer Chemistry Center (CCC), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Dirk Zahn
- Theoretical Chemistry/Computer Chemistry Center (CCC), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Christoph Korbmacher
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Alexandr V Ilyaskin
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
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2
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Carrisoza-Gaytan R, Mutchler SM, Carattino F, Soong J, Dalghi MG, Wu P, Wang W, Apodaca G, Satlin LM, Kleyman TR. PIEZO1 is a distal nephron mechanosensor and is required for flow-induced K+ secretion. J Clin Invest 2024; 134:e174806. [PMID: 38426496 PMCID: PMC10904061 DOI: 10.1172/jci174806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 01/02/2024] [Indexed: 03/02/2024] Open
Abstract
Ca2+-activated BK channels in renal intercalated cells (ICs) mediate luminal flow-induced K+ secretion (FIKS), but how ICs sense increased flow remains uncertain. We examined whether PIEZO1, a mechanosensitive Ca2+-permeable channel expressed in the basolateral membranes of ICs, is required for FIKS. In isolated cortical collecting ducts (CCDs), the mechanosensitive cation-selective channel inhibitor GsMTx4 dampened flow-induced increases in intracellular Ca2+ concentration ([Ca2+]i), whereas the PIEZO1 activator Yoda1 increased [Ca2+]i and BK channel activity. CCDs from mice fed a high-K+ (HK) diet exhibited a greater Yoda1-dependent increase in [Ca2+]i than CCDs from mice fed a control K+ diet. ICs in CCDs isolated from mice with a targeted gene deletion of Piezo1 in ICs (IC-Piezo1-KO) exhibited a blunted [Ca2+]i response to Yoda1 or increased flow, with an associated loss of FIKS in CCDs. Male IC-Piezo1-KO mice selectively exhibited an increased blood [K+] in response to an oral K+ bolus and blunted urinary K+ excretion following a volume challenge. Whole-cell expression of BKα subunit was reduced in ICs of IC-Piezo1-KO mice fed an HK diet. We conclude that PIEZO1 mediates flow-induced basolateral Ca2+ entry into ICs, is upregulated in the CCD in response to an HK diet, and is necessary for FIKS.
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Affiliation(s)
| | | | - Francisco Carattino
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Joanne Soong
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Marianela G. Dalghi
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Peng Wu
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - WenHui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA
| | - Gerard Apodaca
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Cell Biology and
| | - Lisa M. Satlin
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Thomas R. Kleyman
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Cell Biology and
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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3
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Hochstetler A, Smith H, Reed M, Hulme L, Territo P, Bedwell A, Persohn S, Perrotti N, D'Antona L, Musumeci F, Schenone S, Blazer-Yost BL. Inhibition of serum- and glucocorticoid-induced kinase 1 ameliorates hydrocephalus in preclinical models. Fluids Barriers CNS 2023; 20:61. [PMID: 37596666 PMCID: PMC10439616 DOI: 10.1186/s12987-023-00461-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 07/28/2023] [Indexed: 08/20/2023] Open
Abstract
BACKGROUND Hydrocephalus is a pathological accumulation of cerebrospinal fluid (CSF), leading to ventriculomegaly. Hydrocephalus may be primary or secondary to traumatic brain injury, infection, or intracranial hemorrhage. Regardless of cause, current treatment involves surgery to drain the excess CSF. Importantly, there are no long-term, effective pharmaceutical treatments and this represents a clinically unmet need. Many forms of hydrocephalus involve dysregulation in water and electrolyte homeostasis, making this an attractive, druggable target. METHODS In vitro, a combination of electrophysiological and fluid flux assays was used to elucidate secretory transepithelial electrolyte and fluid flux in a human cell culture model of the choroid plexus epithelium and to determine the involvement of serum-, glucocorticoid-induced kinase 1 (SGK1). In vivo, MRI studies were performed in a genetic rat model of hydrocephalus to determine effects of inhibition of SGK1 with a novel inhibitor, SI113. RESULTS In the cultured cell line, SI113 reduced secretory transepithelial electrolyte and fluid flux. In vivo, SI113 blocks the development of hydrocephalus with no effect on ventricular size of wild-type animals and no overt toxic effects. Mechanistically, the development of hydrocephalus in the rat model involves an increase in activated, phosphorylated SGK1 with no change in the total amount of SGK1. SI113 inhibits phosphorylation with no changes in total SGK1 levels in the choroid plexus epithelium. CONCLUSION These data provide a strong preclinical basis for the use of SGK1 inhibitors in the treatment of hydrocephalus.
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Affiliation(s)
- Alexandra Hochstetler
- Department of Biology, SL358, Indiana University Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN, 46202, USA
| | - Hillary Smith
- Department of Biology, SL358, Indiana University Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN, 46202, USA
| | - Makenna Reed
- Department of Biology, SL358, Indiana University Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN, 46202, USA
| | - Louise Hulme
- Department of Biology, SL358, Indiana University Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN, 46202, USA
| | - Paul Territo
- Department of Medicine, Indiana University School of Medicine, Indianapolis, USA
| | - Amanda Bedwell
- Department of Medicine, Indiana University School of Medicine, Indianapolis, USA
| | - Scott Persohn
- Department of Medicine, Indiana University School of Medicine, Indianapolis, USA
| | - Nicola Perrotti
- Dipartimento di Scienze della Salute, Università" Magna Graecia" di Catanzaro, Catanzaro, Italy
| | - Lucia D'Antona
- Dipartimento di Scienze della Salute, Università" Magna Graecia" di Catanzaro, Catanzaro, Italy
| | | | | | - Bonnie L Blazer-Yost
- Department of Biology, SL358, Indiana University Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN, 46202, USA.
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Wang T, Zhai Y, Xue H, Zhou W, Ding Y, Nie H. Regulation of Epithelial Sodium Transport by SARS-CoV-2 Is Closely Related with Fibrinolytic System-Associated Proteins. Biomolecules 2023; 13:biom13040578. [PMID: 37189326 DOI: 10.3390/biom13040578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/08/2023] [Accepted: 03/21/2023] [Indexed: 05/17/2023] Open
Abstract
Dyspnea and progressive hypoxemia are the main clinical features of patients with coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Pulmonary pathology shows diffuse alveolar damage with edema, hemorrhage, and the deposition of fibrinogens in the alveolar space, which are consistent with the Berlin Acute Respiratory Distress Syndrome Criteria. The epithelial sodium channel (ENaC) is a key channel protein in alveolar ion transport and the rate-limiting step for pulmonary edema fluid clearance, the dysregulation of which is associated with acute lung injury/acute respiratory distress syndrome. The main protein of the fibrinolysis system, plasmin, can bind to the furin site of γ-ENaC and induce it to an activation state, facilitating pulmonary fluid reabsorption. Intriguingly, the unique feature of SARS-CoV-2 from other β-coronaviruses is that the spike protein of the former has the same furin site (RRAR) with ENaC, suggesting that a potential competition exists between SARS-CoV-2 and ENaC for the cleavage by plasmin. Extensive pulmonary microthrombosis caused by disorders of the coagulation and fibrinolysis system has also been seen in COVID-19 patients. To some extent, high plasmin (ogen) is a common risk factor for SARS-CoV-2 infection since an increased cleavage by plasmin accelerates virus invasion. This review elaborates on the closely related relationship between SARS-CoV-2 and ENaC for fibrinolysis system-related proteins, aiming to clarify the regulation of ENaC under SARS-CoV-2 infection and provide a novel reference for the treatment of COVID-19 from the view of sodium transport regulation in the lung epithelium.
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Affiliation(s)
- Tingyu Wang
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang 110122, China
| | - Yiman Zhai
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang 110122, China
| | - Hao Xue
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang 110122, China
| | - Wei Zhou
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang 110122, China
| | - Yan Ding
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang 110122, China
| | - Hongguang Nie
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang 110122, China
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Kourpa A, Kaiser-Graf D, Sporbert A, Philippe A, Catar R, Rothe M, Mangelsen E, Schulz A, Bolbrinker J, Kreutz R, Panáková D. 15-keto-Prostaglandin E2 exhibits bioactive role by modulating glomerular cytoarchitecture through EP2/EP4 receptors. Life Sci 2022; 310:121114. [DOI: 10.1016/j.lfs.2022.121114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/06/2022] [Accepted: 10/17/2022] [Indexed: 11/05/2022]
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6
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Yang T, Song C, Ralph DL, Andrews P, Sparks MA, Koller BH, McDonough AA, Coffman TM. Cell-Specific Actions of the Prostaglandin E-Prostanoid Receptor 4 Attenuating Hypertension: A Dominant Role for Kidney Epithelial Cells Compared With Macrophages. J Am Heart Assoc 2022; 11:e026581. [PMID: 36172956 PMCID: PMC9673718 DOI: 10.1161/jaha.122.026581] [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] [Indexed: 11/30/2022]
Abstract
Background A beneficial role for prostanoids in hypertension is suggested by clinical studies showing nonsteroidal anti-inflammatory drugs, which block the production of all prostanoids, cause sodium retention and exacerbate hypertension. Among prostanoids, prostaglandin E2 and its E-prostanoid receptor 4 receptor (EP4R) have been implicated in blood pressure control. Our previous study found that conditional deletion of EP4R from all tissues in adult mice exacerbates angiotensin II-dependent hypertension, suggesting a powerful effect of EP4R to resist blood pressure elevation. We also found that elimination of EP4R from vascular smooth muscle cells did not affect the severity of hypertension, suggesting nonvascular targets of prostaglandin E mediate this antihypertensive effect. Methods and Results Here we generated mice with cell-specific deletion of EP4R from macrophage-specific EP4 receptor knockouts or kidney epithelial cells (KEKO) to assess the contributions of EP4R in these cells to hypertension pathogenesis. Macrophage-specific EP4 receptor knockouts showed similar blood pressure responses to alterations in dietary sodium or chronic angiotensin II infusion as Controls. By contrast, angiotensin II-dependent hypertension was significantly augmented in KEKOs (mean arterial pressure: 146±3 mm Hg) compared with Controls (137±4 mm Hg; P=0.02), which was accompanied by impaired natriuresis in KEKOs. Because EP4R expression in the kidney is enriched in the collecting duct, we compared responses to amiloride in angiotensin II-infused KEKOs and Controls. Blockade of the epithelial sodium channel with amiloride caused exaggerated natriuresis in KEKOs compared with Controls (0.21±0.01 versus 0.15±0.02 mmol/24 hour per 20 g; P=0.015). Conclusions Our data suggest EP4R in kidney epithelia attenuates hypertension. This antihypertension effect of EP4R may be mediated by reducing the activity of the epithelial sodium channel, thereby promoting natriuresis.
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Affiliation(s)
- Ting Yang
- Division of Nephrology‐Department of MedicineDuke UniversityDurhamNC
| | - Chengcheng Song
- Division of Nephrology‐Department of MedicineDuke UniversityDurhamNC,Department of AnesthesiologyTianjin Medical University General HospitalTianjinChina
| | - Donna L. Ralph
- Department of Physiology and NeuroscienceKeck School of Medicine of the University of Southern CaliforniaLos AngelesCA
| | - Portia Andrews
- Division of Nephrology‐Department of MedicineDuke UniversityDurhamNC
| | - Matthew A. Sparks
- Division of Nephrology‐Department of MedicineDuke UniversityDurhamNC
| | | | - Alicia A. McDonough
- Department of Physiology and NeuroscienceKeck School of Medicine of the University of Southern CaliforniaLos AngelesCA
| | - Thomas M. Coffman
- Division of Nephrology‐Department of MedicineDuke UniversityDurhamNC,Cardiovascular and Metabolic Disorders Research ProgramDuke‐National University of Singapore Graduate Medical SchoolSingapore
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Shimada S, Yang C, Kumar V, Mattson DL, Cowley AW. Acute Increase of Renal Perfusion Pressure Causes Rapid Activation of mTORC1 (Mechanistic Target Of Rapamycin Complex 1) and Leukocyte Infiltration. Hypertension 2022; 79:1180-1189. [PMID: 35291809 PMCID: PMC9098670 DOI: 10.1161/hypertensionaha.121.18643] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 02/25/2022] [Indexed: 11/16/2022]
Abstract
BACKGROUND The present study in Sprague-Dawley rats determined the effects of a rapid rise of renal perfusion pressure (RPP) upon the activation of mTOR (mechanistic target of rapamycin), and the effects upon the infiltration of CD68-positive macrophages/monocytes and CD3-positive T lymphocytes into the kidneys. METHODS RPP was elevated by 40 mm Hg for 30 minutes in male Sprague-Dawley rats while measuring renal blood flow and urine flow rate. Sham rats were studied in the same way, but RPP was not changed. Since initial studies found that the acute increase of RPP resulted in activation of mTORC1 (phosphorylation of S6S235/236), the effects of inhibition of mTORC1 with rapamycin pretreatment were then determined. RESULTS It was found that a 30-minute increase of RPP (≈40 mm Hg) resulted in an 8-fold increase of renal sodium excretion which was blunted by rapamycin treatment. Renal blood flow was not affected by the elevation of RPP. Activation of mTORC1 was observed. Significant increases in CD68-positive macrophages were found in both the cortex (intraglomerular and periglomerular regions) and in the outer medullary interstitial regions of the kidney and prevented by rapamycin treatment. Increases in CD3-positive T lymphocytes were observed exclusively in the periglomerular regions and prevented by rapamycin treatment. Upregulation of several proinflammatory markers was observed. CONCLUSIONS We conclude that elevation of RPP rapidly activates mTORC1 resulting in infiltration of immune cells into the kidney.
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Affiliation(s)
- Satoshi Shimada
- Department of Physiology, Medical College of Wisconsin, Milwaukee (S.S., C.Y., V.K., D.L.M., A.W.C.)
| | - Chun Yang
- Department of Physiology, Medical College of Wisconsin, Milwaukee (S.S., C.Y., V.K., D.L.M., A.W.C.)
| | - Vikash Kumar
- Department of Physiology, Medical College of Wisconsin, Milwaukee (S.S., C.Y., V.K., D.L.M., A.W.C.)
| | - David L Mattson
- Department of Physiology, Medical College of Wisconsin, Milwaukee (S.S., C.Y., V.K., D.L.M., A.W.C.)
- Now with: Department of Physiology, Medical College of Georgia at Augusta University (D.L.M.)
| | - Allen W Cowley
- Department of Physiology, Medical College of Wisconsin, Milwaukee (S.S., C.Y., V.K., D.L.M., A.W.C.)
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8
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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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9
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Sure F, Bertog M, Afonso S, Diakov A, Rinke R, Madej MG, Wittmann S, Gramberg T, Korbmacher C, Ilyaskin AV. Transmembrane serine protease 2 (TMPRSS2) proteolytically activates the epithelial sodium channel (ENaC) by cleaving the channel's γ-subunit. J Biol Chem 2022; 298:102004. [PMID: 35504352 PMCID: PMC9163703 DOI: 10.1016/j.jbc.2022.102004] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 04/21/2022] [Accepted: 04/27/2022] [Indexed: 01/09/2023] Open
Abstract
The epithelial sodium channel (ENaC) is a heterotrimer consisting of α-, β-, and γ-subunits. Channel activation requires proteolytic release of inhibitory tracts from the extracellular domains of α-ENaC and γ-ENaC; however, the proteases involved in the removal of the γ-inhibitory tract remain unclear. In several epithelial tissues, ENaC is coexpressed with the transmembrane serine protease 2 (TMPRSS2). Here, we explored the effect of human TMPRSS2 on human αβγ-ENaC heterologously expressed in Xenopus laevis oocytes. We found that coexpression of TMPRSS2 stimulated ENaC-mediated whole-cell currents by approximately threefold, likely because of an increase in average channel open probability. Furthermore, TMPRSS2-dependent ENaC stimulation was not observed using a catalytically inactive TMPRSS2 mutant and was associated with fully cleaved γ-ENaC in the intracellular and cell surface protein fractions. This stimulatory effect of TMPRSS2 on ENaC was partially preserved when inhibiting its proteolytic activity at the cell surface using aprotinin but was abolished when the γ-inhibitory tract remained attached to its binding site following introduction of two cysteine residues (S155C–Q426C) to form a disulfide bridge. In addition, computer simulations and site-directed mutagenesis experiments indicated that TMPRSS2 can cleave γ-ENaC at sites both proximal and distal to the γ-inhibitory tract. This suggests a dual role of TMPRSS2 in the proteolytic release of the γ-inhibitory tract. Finally, we demonstrated that TMPRSS2 knockdown in cultured human airway epithelial cells (H441) reduced baseline proteolytic activation of endogenously expressed ENaC. Thus, we conclude that TMPRSS2 is likely to contribute to proteolytic ENaC activation in epithelial tissues in vivo.
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Affiliation(s)
- Florian Sure
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - Marko Bertog
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - Sara Afonso
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - Alexei Diakov
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - Ralf Rinke
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - M Gregor Madej
- Department of Biophysics II/Structural Biology, University of Regensburg, Regensburg, Germany
| | - Sabine Wittmann
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsklinikum Erlangen, Institute of Clinical and Molecular Virology, Erlangen, Germany
| | - Thomas Gramberg
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsklinikum Erlangen, Institute of Clinical and Molecular Virology, Erlangen, Germany
| | - Christoph Korbmacher
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany.
| | - Alexandr V Ilyaskin
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
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Xu C, Yang G, Fu Z, Chen Y, Xie S, Wang F, Yang T. Na +-Retaining Action of COX-2 (Cyclooxygenase-2)/EP 1 Pathway in the Collecting Duct via Activation of Intrarenal Renin-Angiotensin-Aldosterone System and Epithelial Sodium Channel. Hypertension 2022; 79:1190-1202. [PMID: 35296155 DOI: 10.1161/hypertensionaha.121.17245] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The collecting duct (CD) is a major site of both biosynthesis and action of prostaglandin E2 as highlighted by the predominant expression of COX-2 (cyclooxygenase-2) and some E-prostanoid (EP) subtypes at this nephron site. The purpose of this study was to determine the relevance and mechanism of CD COX-2/prostaglandin E2/EP1 signaling for the regulation of Na+ hemostasis during Na+ depletion. METHODS Mice with Aqp2Cre-driven deletion of COX-2 (COX-2fl/flAqp2Cre+) or the EP1 subtype (EP1fl/flAqp2Cre+) were generated and the Na+-wasting phenotype of these mice during low-salt (LS) intake was examined. EP subtypes responsible for prostaglandin E2-induced local renin response were analyzed in primary cultured mouse inner medullary CD cells. RESULTS Following 28-day LS intake, COX-2fl/flAqp2Cre+ mice exhibited a higher urinary Na+ excretion and lower cumulative Na+ balance, accompanied with suppressed intrarenal renin, AngII (angiotensin II), and aldosterone, expression of CYP11B2 (cytochrome P450 family 11 subfamily B member 2), and blunted expression of epithelial sodium channel subunits compared to floxed controls (COX-2fl/flAqp2Cre-), whereas no differences were observed for indices of systemic renin-angiotensin-aldosterone system. In cultured CD cells, exposure to prostaglandin E2 stimulated release of soluble (pro)renin receptor, prorenin/renin and aldosterone and the stimulation was more sensitive to antagonism of EP1 as compared other EP subtypes. Subsequently, EP1fl/flAqp2Cre+ mice largely recapitulated Na+-wasting phenotype seen in COX-2fl/flAqp2Cre+ mice. CONCLUSIONS The study for the first time reports that CD COX-2/EP1 pathway might play a key role in maintenance of Na+ homeostasis in the face of Na+ depletion, at least in part, through activation of intrarenal renin-angiotensin-aldosterone-system and epithelial sodium channel.
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Affiliation(s)
- Chuanming Xu
- Department of Internal Medicine, University of Utah and Veterans Affairs Medical Center, Salt Lake City
| | - Guangrui Yang
- Department of Internal Medicine, University of Utah and Veterans Affairs Medical Center, Salt Lake City
| | - Ziwei Fu
- Department of Internal Medicine, University of Utah and Veterans Affairs Medical Center, Salt Lake City
| | - Yanting Chen
- Department of Internal Medicine, University of Utah and Veterans Affairs Medical Center, Salt Lake City
| | - Shiying Xie
- Department of Internal Medicine, University of Utah and Veterans Affairs Medical Center, Salt Lake City
| | - Fei Wang
- Department of Internal Medicine, University of Utah and Veterans Affairs Medical Center, Salt Lake City
| | - Tianxin Yang
- Department of Internal Medicine, University of Utah and Veterans Affairs Medical Center, Salt Lake City
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11
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Zapf AM, Grimm PR, Al-Qusairi L, Delpire E, Welling PA. Low Salt Delivery Triggers Autocrine Release of Prostaglandin E2 From the Aldosterone-Sensitive Distal Nephron in Familial Hyperkalemic Hypertension Mice. Front Physiol 2022; 12:787323. [PMID: 35069250 PMCID: PMC8770744 DOI: 10.3389/fphys.2021.787323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/19/2021] [Indexed: 11/13/2022] Open
Abstract
Aberrant activation of with-no-lysine kinase (WNK)-STE20/SPS1-related proline-alanine-rich protein kinase (SPAK) kinase signaling in the distal convoluted tubule (DCT) causes unbridled activation of the thiazide-sensitive sodium chloride cotransporter (NCC), leading to familial hyperkalemic hypertension (FHHt) in humans. Studies in FHHt mice engineered to constitutively activate SPAK specifically in the DCT (CA-SPAK mice) revealed maladaptive remodeling of the aldosterone sensitive distal nephron (ASDN), characterized by decrease in the potassium excretory channel, renal outer medullary potassium (ROMK), and epithelial sodium channel (ENaC), that contributes to the hyperkalemia. The mechanisms by which NCC activation in DCT promotes remodeling of connecting tubule (CNT) are unknown, but paracrine communication and reduced salt delivery to the ASDN have been suspected. Here, we explore the involvement of prostaglandin E2 (PGE2). We found that PGE2 and the terminal PGE2 synthase, mPGES1, are increased in kidney cortex of CA-SPAK mice, compared to control or SPAK KO mice. Hydrochlorothiazide (HCTZ) reduced PGE2 to control levels, indicating increased PGE2 synthesis is dependent on increased NCC activity. Immunolocalization studies revealed mPGES1 is selectively increased in the CNT of CA-SPAK mice, implicating low salt-delivery to ASDN as the trigger. Salt titration studies in an in vitro ASDN cell model, mouse CCD cell (mCCD-CL1), confirmed PGE2 synthesis is activated by low salt, and revealed that response is paralleled by induction of mPGES1 gene expression. Finally, inhibition of the PGE2 receptor, EP1, in CA-SPAK mice partially restored potassium homeostasis as it partially rescued ROMK protein abundance, but not ENaC. Together, these data indicate low sodium delivery to the ASDN activates PGE2 synthesis and this inhibits ROMK through autocrine activation of the EP1 receptor. These findings provide new insights into the mechanism by which activation of sodium transport in the DCT causes remodeling of the ASDN.
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Affiliation(s)
- Ava M Zapf
- Molecular Medicine, Graduate Program in Life Sciences, University of Maryland Medical School, Baltimore, MD, United States
| | - Paul R Grimm
- Department of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Lama Al-Qusairi
- Department of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University Medical School, Nashville, TN, United States
| | - Paul A Welling
- Department of Medicine, Johns Hopkins University, Baltimore, MD, United States.,Department of Physiology, Johns Hopkins University, Baltimore, MD, United States
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12
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Sholokh A, Klussmann E. Local cyclic adenosine monophosphate signalling cascades-Roles and targets in chronic kidney disease. Acta Physiol (Oxf) 2021; 232:e13641. [PMID: 33660401 DOI: 10.1111/apha.13641] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/26/2021] [Accepted: 03/01/2021] [Indexed: 12/20/2022]
Abstract
The molecular mechanisms underlying chronic kidney disease (CKD) are poorly understood and treatment options are limited, a situation underpinning the need for elucidating the causative molecular mechanisms and for identifying innovative treatment options. It is emerging that cyclic 3',5'-adenosine monophosphate (cAMP) signalling occurs in defined cellular compartments within nanometre dimensions in processes whose dysregulation is associated with CKD. cAMP compartmentalization is tightly controlled by a specific set of proteins, including A-kinase anchoring proteins (AKAPs) and phosphodiesterases (PDEs). AKAPs such as AKAP18, AKAP220, AKAP-Lbc and STUB1, and PDE4 coordinate arginine-vasopressin (AVP)-induced water reabsorption by collecting duct principal cells. However, hyperactivation of the AVP system is associated with kidney damage and CKD. Podocyte injury involves aberrant AKAP signalling. cAMP signalling in immune cells can be local and slow the progression of inflammatory processes typical for CKD. A major risk factor of CKD is hypertension. cAMP directs the release of the blood pressure regulator, renin, from juxtaglomerular cells, and plays a role in Na+ reabsorption through ENaC, NKCC2 and NCC in the kidney. Mutations in the cAMP hydrolysing PDE3A that cause lowering of cAMP lead to hypertension. Another major risk factor of CKD is diabetes mellitus. AKAP18 and AKAP150 and several PDEs are involved in insulin release. Despite the increasing amount of data, an understanding of functions of compartmentalized cAMP signalling with relevance for CKD is fragmentary. Uncovering functions will improve the understanding of physiological processes and identification of disease-relevant aberrations may guide towards new therapeutic concepts for the treatment of CKD.
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Affiliation(s)
- Anastasiia Sholokh
- Max‐Delbrück‐Center for Molecular Medicine (MDC) Helmholtz Association Berlin Germany
| | - Enno Klussmann
- Max‐Delbrück‐Center for Molecular Medicine (MDC) Helmholtz Association Berlin Germany
- DZHK (German Centre for Cardiovascular Research) Berlin Germany
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