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Kashlan OB, Wang XP, Sheng S, Kleyman TR. Epithelial Na + Channels Function as Extracellular Sensors. Compr Physiol 2024; 14:1-41. [PMID: 39109974 PMCID: PMC11309579 DOI: 10.1002/cphy.c230015] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
The epithelial Na + channel (ENaC) resides on the apical surfaces of specific epithelia in vertebrates and plays a critical role in extracellular fluid homeostasis. Evidence that ENaC senses the external environment emerged well before the molecular identity of the channel was reported three decades ago. This article discusses progress toward elucidating the mechanisms through which specific external factors regulate ENaC function, highlighting insights gained from structural studies of ENaC and related family members. It also reviews our understanding of the role of ENaC regulation by the extracellular environment in physiology and disease. After familiarizing the reader with the channel's physiological roles and structure, we describe the central role protein allostery plays in ENaC's sensitivity to the external environment. We then discuss each of the extracellular factors that directly regulate the channel: proteases, cations and anions, shear stress, and other regulators specific to particular extracellular compartments. For each regulator, we discuss the initial observations that led to discovery, studies investigating molecular mechanism, and the physiological and pathophysiological implications of regulation. © 2024 American Physiological Society. Compr Physiol 14:5407-5447, 2024.
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Affiliation(s)
- Ossama B. Kashlan
- Department of Medicine, Renal-Electrolyte Division,
University of Pittsburgh, Pittsburgh, Pennsylvania
- Department of Computational and Systems Biology, University
of Pittsburgh, Pittsburgh, Pennsylvania
| | - Xue-Ping Wang
- Department of Medicine, Renal-Electrolyte Division,
University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Shaohu Sheng
- Department of Medicine, Renal-Electrolyte Division,
University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Thomas R. Kleyman
- Department of Medicine, Renal-Electrolyte Division,
University of Pittsburgh, Pittsburgh, Pennsylvania
- Department of Cell Biology, University of Pittsburgh,
Pittsburgh, Pennsylvania
- Department of Pharmacology and Chemical Biology, University
of Pittsburgh, Pittsburgh, Pennsylvania
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2
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Bissinger R, Qadri SM, Artunc F. Eryptosis: a driver of anemia in chronic kidney disease. Curr Opin Nephrol Hypertens 2024; 33:220-225. [PMID: 37987655 DOI: 10.1097/mnh.0000000000000957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
PURPOSE OF REVIEW Anemia, characterized by a reduction in red blood cell (RBC) count or hemoglobin concentration, commonly accompanies chronic kidney disease (CKD), significantly impacting patients' quality of life. This review delves into the multifaceted nature of anemia in CKD, with a focus on novel mechanisms, particularly the dysregulation of eryptosis or programmed cell death of RBCs, leading to shortened RBC lifespan. RECENT FINDINGS Recent studies in CKD patients and mouse models revealed that eryptosis, driven by factors such as uremic toxins, inflammation, and imbalances in calcium homeostasis, plays a pivotal role in the development of renal anemia. Dysregulated eryptosis results in premature RBC destruction, exacerbating the hypoproliferative character of anemia in CKD. SUMMARY Recognizing the intricate relationship between eryptosis and anemia in CKD opens promising prospects for improving patient outcomes and enhancing our understanding of this complex condition. Future research and therapeutic development in this area hold the potential to improve anemia treatment of CKD patients.
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Affiliation(s)
- Rosi Bissinger
- Department of Internal Medicine, Division of Diabetology, Endocrinology and Nephrology, University Hospital Tübingen, Germany
| | - Syed M Qadri
- Faculty of Health Sciences, Ontario Tech University, Oshawa, ON, Canada
| | - Ferruh Artunc
- Department of Internal Medicine, Division of Diabetology, Endocrinology and Nephrology, University Hospital Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen
- German Center for Diabetes Research at the University of Tübingen, Tübingen, Germany
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3
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Ortmann LA, Nandi S, Li YL, Zheng H, Patel KP. Activation of renal epithelial Na + channels (ENaC) in infants with congenital heart disease. Front Pediatr 2024; 12:1338672. [PMID: 38379911 PMCID: PMC10876900 DOI: 10.3389/fped.2024.1338672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 01/25/2024] [Indexed: 02/22/2024] Open
Abstract
Introduction This study was designed to measure the concentration and activity of urinary proteases that activate renal epithelial sodium channel (ENaC) mediated Na+ transport in infants with congenital heart disease, a potential mechanism for fluid retention. Methods Urine samples from infants undergoing cardiac surgery were collected at three time points: T1) pre-operatively, T2) 6-8 h after surgery, and T3) 24 h after diuretics. Urine was collected from five heathy infant controls. The urine was tested for four proteases and whole-cell patch-clamp testing was conducted in renal collecting duct M-1 cells to test whether patient urine increased Na+ currents consistent with ENaC activation. Results Heavy chain of plasminogen, furin, and prostasin were significantly higher in cardiac patients prior to surgery compared to controls. There was no difference in most proteases before and after surgery. Urine from cardiac patients produced a significantly greater increase in Na+ inward currents compared to healthy controls. Conclusion Urine from infants with congenital heart disease is richer in proteases and has the potential to increase activation of ENaC in the nephron to enhance Na+ reabsorption, which may lead to fluid retention in this population.
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Affiliation(s)
- Laura A. Ortmann
- Department of Pediatrics, University of Nebraska Medical Center, Omaha, NE, United States
| | - Shyam Nandi
- Department of Integrative and Cellular Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Yu-long Li
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Hong Zheng
- Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States
| | - Kaushik P. Patel
- Department of Integrative and Cellular Physiology, University of Nebraska Medical Center, Omaha, NE, United States
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Iwata Y, Deng Q, Kakizoe Y, Nakagawa T, Miyasato Y, Nakagawa M, Nishiguchi K, Nagayoshi Y, Narita Y, Izumi Y, Kuwabara T, Adachi M, Mukoyama M. A Serine Protease Inhibitor, Camostat Mesilate, Suppresses Urinary Plasmin Activity and Alleviates Hypertension and Podocyte Injury in Dahl Salt-Sensitive Rats. Int J Mol Sci 2023; 24:15743. [PMID: 37958726 PMCID: PMC10650472 DOI: 10.3390/ijms242115743] [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: 10/07/2023] [Revised: 10/25/2023] [Accepted: 10/28/2023] [Indexed: 11/15/2023] Open
Abstract
In proteinuric renal diseases, the serine protease (SP) plasmin activates the epithelial sodium channel (ENaC) by cleaving its γ subunit. We previously demonstrated that a high-salt (HS) diet provoked hypertension and proteinuria in Dahl salt-sensitive (DS) rats, accompanied by γENaC activation, which were attenuated by camostat mesilate (CM), an SP inhibitor. However, the effects of CM on plasmin activity in DS rats remain unclear. In this study, we investigated the effects of CM on plasmin activity, ENaC activation, and podocyte injury in DS rats. The DS rats were divided into the control diet, HS diet (8.0% NaCl), and HS+CM diet (0.1% CM) groups. After weekly blood pressure measurement and 24-h urine collection, the rats were sacrificed at 5 weeks. The HS group exhibited hypertension, massive proteinuria, increased urinary plasmin, and γENaC activation; CM treatment suppressed these changes. CM prevented plasmin(ogen) attachment to podocytes and mitigated podocyte injury by reducing the number of apoptotic glomerular cells, inhibiting protease-activated receptor-1 activation, and suppressing inflammatory and fibrotic cytokine expression. Our findings highlight the detrimental role of urinary plasmin in the pathogenesis of salt-sensitive hypertension and glomerular injury. Targeting plasmin with SP inhibitors, such as CM, may be a promising therapeutic approach for these conditions.
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Affiliation(s)
- Yasunobu Iwata
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Qinyuan Deng
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Yutaka Kakizoe
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
- Comprehensive Clinical Education, Training and Development Center, Kumamoto University Hospital, Kumamoto 860-8556, Japan
| | - Terumasa Nakagawa
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Yoshikazu Miyasato
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Miyuki Nakagawa
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Kayo Nishiguchi
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Yu Nagayoshi
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Yuki Narita
- Department of Pharmacy, Kumamoto University Hospital, Kumamoto 860-8556, Japan
| | - Yuichiro Izumi
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Takashige Kuwabara
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Masataka Adachi
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
| | - Masashi Mukoyama
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
- Comprehensive Clinical Education, Training and Development Center, Kumamoto University Hospital, Kumamoto 860-8556, Japan
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5
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The serine protease plasmin plays detrimental roles in epithelial sodium channel activation and podocyte injury in Dahl salt-sensitive rats. Hypertens Res 2023; 46:50-62. [PMID: 36241707 DOI: 10.1038/s41440-022-01064-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 09/06/2022] [Accepted: 09/26/2022] [Indexed: 02/03/2023]
Abstract
Salt-sensitive hypertension is associated with poor clinical outcomes. The epithelial sodium channel (ENaC) in the kidney plays pivotal roles in sodium reabsorption and blood pressure regulation, in which its γ subunit is activated by extracellular serine proteases. In proteinuric nephropathies, plasmin filtered through injured glomeruli reportedly activates γENaC in the distal nephron and causes podocyte injury. We previously reported that Dahl salt-sensitive (DS) rats fed a high-salt (HS) diet developed hypertension and proteinuria along with γENaC activation and that a synthetic serine protease inhibitor, camostat mesilate, mitigated these changes. However, the role of plasmin in DS rats remained unclear. In this study, we evaluated the relationship between plasmin and hypertension as well as podocyte injury and the effects of plasmin inhibitors in DS rats. Five-week-old DS rats were divided into normal-salt diet, HS diet, and HS+plasmin inhibitor (either tranexamic acid [TA] or synthetic plasmin inhibitor YO-2) groups. After blood pressure measurement and 24 h urine collection over 5 weeks, rats were sacrificed for biochemical analyses. The HS group displayed severe hypertension and proteinuria together with activation of plasmin in urine and γENaC in the kidney, which was significantly attenuated by YO-2 but not TA. YO-2 inhibited the attachment of plasmin(ogen) to podocytes and alleviated podocyte injury by inhibiting apoptosis and inflammatory/profibrotic cytokines. YO-2 also suppressed upregulation of protease-activated receptor-1 and phosphorylated ERK1/2. These results indicate an important role of plasmin in the development of salt-sensitive hypertension and related podocyte injury, suggesting plasmin inhibition as a potential therapeutic strategy.
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Kidney-Specific CAP1/Prss8-Deficient Mice Maintain ENaC-Mediated Sodium Balance through an Aldosterone Independent Pathway. Int J Mol Sci 2022; 23:ijms23126745. [PMID: 35743186 PMCID: PMC9224322 DOI: 10.3390/ijms23126745] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/10/2022] [Accepted: 06/15/2022] [Indexed: 12/14/2022] Open
Abstract
The serine protease prostasin (CAP1/Prss8, channel-activating protease-1) is a confirmed in vitro and in vivo activator of the epithelial sodium channel ENaC. To test whether proteolytic activity or CAP1/Prss8 abundance itself are required for ENaC activation in the kidney, we studied animals either hetero- or homozygous mutant at serine 238 (S238A; Prss8cat/+ and Prss8cat/cat), and renal tubule-specific CAP1/Prss8 knockout (Prss8PaxLC1) mice. When exposed to varying Na+-containing diets, no changes in Na+ and K+ handling and only minor changes in the expression of Na+ and K+ transporting protein were found in both models. Similarly, the α- or γENaC subunit cleavage pattern did not differ from control mice. On standard and low Na+ diet, Prss8cat/+ and Prss8cat/cat mice exhibited standard plasma aldosterone levels and unchanged amiloride-sensitive rectal potential difference indicating adapted ENaC activity. Upon Na+ deprivation, mice lacking the renal CAP1/Prss8 expression (Prss8PaxLC1) exhibit significantly decreased plasma aldosterone and lower K+ levels but compensate by showing significantly higher plasma renin activity. Our data clearly demonstrated that the catalytic activity of CAP1/Prss8 is dispensable for proteolytic ENaC activation. CAP1/Prss8-deficiency uncoupled ENaC activation from its aldosterone dependence, but Na+ homeostasis is maintained through alternative pathways.
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Xiao M, Bohnert BN, Grahammer F, Artunc F. Rodent models to study sodium retention in experimental nephrotic syndrome. Acta Physiol (Oxf) 2022; 235:e13844. [PMID: 35569011 DOI: 10.1111/apha.13844] [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: 02/26/2022] [Revised: 05/02/2022] [Accepted: 05/10/2022] [Indexed: 12/12/2022]
Abstract
Sodium retention and edema are hallmarks of nephrotic syndrome (NS). Different experimental rodent models have been established for simulating NS, however, not all of them feature sodium retention which requires proteinuria to exceed a certain threshold. In rats, puromycin aminonucleoside nephrosis (PAN) is a classic NS model introduced in 1955 that was adopted as doxorubicin-induced nephropathy (DIN) in 129S1/SvImJ mice. In recent years, mice with inducible podocin deletion (Nphs2Δipod ) or podocyte apoptosis (POD-ATTAC) have been developed. In these models, sodium retention is thought to be caused by activation of the epithelial sodium channel (ENaC) in the distal nephron through aberrantly filtered serine proteases or proteasuria. Strikingly, rodent NS models follow an identical chronological time course after the development of proteinuria featuring sodium retention within days and spontaneous reversal thereafter. In DIN and Nphs2Δipod mice, inhibition of ENaC by amiloride or urinary serine protease activity by aprotinin prevents sodium retention, opening up new and promising therapeutic approaches that could be translated into the treatment of nephrotic patients. However, the essential serine protease(s) responsible for ENaC activation is (are) still unknown. With the use of nephrotic rodent models, there is the possibility that this (these) will be identified in the future. This review summarizes the various rodent models used to study experimental nephrotic syndrome and the insights gained from these models with regard to the pathophysiology of sodium retention.
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Affiliation(s)
- Mengyun Xiao
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine University Hospital Tübingen Tübingen Germany
| | - Bernhard N. Bohnert
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine University Hospital Tübingen Tübingen Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen Tübingen Germany
- German Center for Diabetes Research (DZD) at the University Tübingen Tübingen Germany
| | - Florian Grahammer
- III. Department of Medicine University Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Ferruh Artunc
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine University Hospital Tübingen Tübingen Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen Tübingen Germany
- German Center for Diabetes Research (DZD) at the University Tübingen Tübingen Germany
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8
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Anand D, Hummler E, Rickman OJ. ENaC activation by proteases. Acta Physiol (Oxf) 2022; 235:e13811. [PMID: 35276025 PMCID: PMC9540061 DOI: 10.1111/apha.13811] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/04/2022] [Accepted: 03/08/2022] [Indexed: 12/13/2022]
Abstract
Proteases are fundamental for a plethora of biological processes, including signalling and tissue remodelling, and dysregulated proteolytic activity can result in pathogenesis. In this review, we focus on a subclass of membrane‐bound and soluble proteases that are defined as channel‐activating proteases (CAPs), since they induce Na+ ion transport through an autocrine mechanism when co‐expressed with the highly amiloride‐sensitive epithelial sodium channel (ENaC) in Xenopus oocytes. These experiments first identified CAP1 (channel‐activating protease 1, prostasin) followed by CAP2 (channel‐activating protease 2, TMPRSS4) and CAP3 (channel‐activating protease 3, matriptase) as in vitro mediators of ENaC current. Since then, more serine‐, cysteine‐ and metalloproteases were confirmed as in vitro CAPs that potentially cleave and regulate ENaC, and thus this nomenclature was not further followed, but is accepted as functional term or alias. The precise mechanism of ENaC modulation by proteases has not been fully elucidated. Studies in organ‐specific protease knockout models revealed evidence for their role in increasing ENaC activity, although the proteases responsible for ENaC activation are yet to be identified. We summarize recent findings in animal models of these CAPs with respect to their implication in ENaC activation. We discuss the consequences of dysregulated CAPs underlying epithelial phenotypes in pathophysiological conditions, and the role of selected protease inhibitors. We believe that these proteases may present interesting therapeutic targets for diseases with aberrant sodium homoeostasis.
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Affiliation(s)
- Deepika Anand
- Department of Biomedical Sciences University of Lausanne Lausanne Switzerland
- National Center of Competence in Research, Kidney.CH Lausanne Switzerland
| | - Edith Hummler
- Department of Biomedical Sciences University of Lausanne Lausanne Switzerland
- National Center of Competence in Research, Kidney.CH Lausanne Switzerland
| | - Olivia J. Rickman
- Department of Biomedical Sciences University of Lausanne Lausanne Switzerland
- National Center of Competence in Research, Kidney.CH Lausanne Switzerland
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9
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Essigke D, Bohnert BN, Janessa A, Wörn M, Omage K, Kalbacher H, Birkenfeld AL, Bugge TH, Szabo R, Artunc F. Sodium retention in nephrotic syndrome is independent of the activation of the membrane-anchored serine protease prostasin (CAP1/PRSS8) and its enzymatic activity. Pflugers Arch 2022; 474:613-624. [PMID: 35312839 PMCID: PMC9117342 DOI: 10.1007/s00424-022-02682-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/25/2022] [Accepted: 03/04/2022] [Indexed: 12/11/2022]
Abstract
Experimental nephrotic syndrome leads to activation of the epithelial sodium channel (ENaC) by proteolysis and promotes renal sodium retention. The membrane-anchored serine protease prostasin (CAP1/PRSS8) is expressed in the distal nephron and participates in proteolytic ENaC regulation by serving as a scaffold for other serine proteases. However, it is unknown whether prostasin is also involved in ENaC-mediated sodium retention of experimental nephrotic syndrome. In this study, we used genetically modified knock-in mice with Prss8 mutations abolishing its proteolytic activity (Prss8-S238A) or prostasin activation (Prss8-R44Q) to investigate the development of sodium retention in doxorubicin-induced nephrotic syndrome. Healthy Prss8-S238A and Prss8-R44Q mice had normal ENaC activity as reflected by the natriuretic response to the ENaC blocker triamterene. After doxorubicin injection, all genotypes developed similar proteinuria. In all genotypes, urinary prostasin excretion increased while renal expression was not altered. In nephrotic mice of all genotypes, triamterene response was similarly increased, consistent with ENaC activation. As a consequence, urinary sodium excretion dropped in all genotypes and mice similarly gained body weight by + 25 ± 3% in Prss8-wt, + 20 ± 2% in Prss8-S238A and + 28 ± 3% in Prss8-R44Q mice (p = 0.16). In Western blots, expression of fully cleaved α- and γ-ENaC was similarly increased in nephrotic mice of all genotypes. In conclusion, proteolytic ENaC activation and sodium retention in experimental nephrotic syndrome are independent of the activation of prostasin and its enzymatic activity and are consistent with the action of aberrantly filtered serine proteases or proteasuria.
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Affiliation(s)
- Daniel Essigke
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Otfried-Mueller-Str.10, 72076, Tuebingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tuebingen, Germany
- German Center for Diabetes Research (DZD) at the University Tübingen, Tuebingen, Germany
| | - Bernhard N Bohnert
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Otfried-Mueller-Str.10, 72076, Tuebingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tuebingen, Germany
- German Center for Diabetes Research (DZD) at the University Tübingen, Tuebingen, Germany
| | - Andrea Janessa
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Otfried-Mueller-Str.10, 72076, Tuebingen, Germany
| | - Matthias Wörn
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Otfried-Mueller-Str.10, 72076, Tuebingen, Germany
| | - Kingsley Omage
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Otfried-Mueller-Str.10, 72076, Tuebingen, Germany
| | | | - Andreas L Birkenfeld
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Otfried-Mueller-Str.10, 72076, Tuebingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tuebingen, Germany
- German Center for Diabetes Research (DZD) at the University Tübingen, Tuebingen, Germany
| | - Thomas H Bugge
- Proteases and Tissue Remodeling Section, NIDCR, National Institutes of Health, Bethesda, MD, USA
| | - Roman Szabo
- Proteases and Tissue Remodeling Section, NIDCR, National Institutes of Health, Bethesda, MD, USA
| | - Ferruh Artunc
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Otfried-Mueller-Str.10, 72076, Tuebingen, Germany.
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tuebingen, Germany.
- German Center for Diabetes Research (DZD) at the University Tübingen, Tuebingen, Germany.
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10
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Wörner S, Bohnert BN, Wörn M, Xiao M, Janessa A, Birkenfeld AL, Amann K, Daniel C, Artunc F. Renal effects of the serine protease inhibitor aprotinin in healthy conscious mice. Acta Pharmacol Sin 2022; 43:111-120. [PMID: 33758357 PMCID: PMC8724274 DOI: 10.1038/s41401-021-00628-1] [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: 12/10/2020] [Accepted: 02/12/2021] [Indexed: 12/31/2022] Open
Abstract
Treatment with aprotinin, a broad-spectrum serine protease inhibitor with a molecular weight of 6512 Da, was associated with acute kidney injury, which was one of the reasons for withdrawal from the market in 2007. Inhibition of renal serine proteases regulating the epithelial sodium channel ENaC could be a possible mechanism. Herein, we studied the effect of aprotinin in wild-type 129S1/SvImJ mice on sodium handling, tubular function, and integrity under a control and low-salt diet. Mice were studied in metabolic cages, and aprotinin was delivered by subcutaneously implanted sustained release pellets (2 mg/day over 10 days). Mean urinary aprotinin concentration ranged between 642 ± 135 (day 2) and 127 ± 16 (day 8) µg/mL . Aprotinin caused impaired sodium preservation under a low-salt diet while stimulating excessive hyperaldosteronism and unexpectedly, proteolytic activation of ENaC. Aprotinin inhibited proximal tubular function leading to glucosuria and proteinuria. Plasma urea and cystatin C concentration increased significantly under aprotinin treatment. Kidney tissues from aprotinin-treated mice showed accumulation of intracellular aprotinin and expression of the kidney injury molecule 1 (KIM-1). In electron microscopy, electron-dense deposits were observed. There was no evidence for kidney injury in mice treated with a lower aprotinin dose (0.5 mg/day). In conclusion, high doses of aprotinin exert nephrotoxic effects by accumulation in the tubular system of healthy mice, leading to inhibition of proximal tubular function and counterregulatory stimulation of ENaC-mediated sodium transport.
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11
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Cole HA, Moore-Lotridge SN, Hawley GD, Jacobson R, Yuasa M, Gewin L, Nyman JS, Flick MJ, Schoenecker JG. The Deleterious Effects of Impaired Fibrinolysis on Skeletal Development Are Dependent on Fibrin(ogen), but Independent of Interlukin-6. Front Cardiovasc Med 2021; 8:768338. [PMID: 34938785 PMCID: PMC8685342 DOI: 10.3389/fcvm.2021.768338] [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: 08/31/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022] Open
Abstract
Chronic diseases in growing children, such as autoimmune disorders, obesity, and cancer, are hallmarked by musculoskeletal growth disturbances and osteoporosis. Many of the skeletal changes in these children are thought to be secondary to chronic inflammation. Recent studies have likewise suggested that changes in coagulation and fibrinolysis may contribute to musculoskeletal growth disturbances. In prior work, we demonstrated that mice deficient in plasminogen, the principal protease of degrading and clearing fibrin matrices, suffer from inflammation-driven systemic osteoporosis and that elimination of fibrinogen resulted in normalization of IL-6 levels and complete rescue of the skeletal phenotype. Given the intimate link between coagulation, fibrinolysis, and inflammation, here we determined if persistent fibrin deposition, elevated IL-6, or both contribute to early skeletal aging and physeal disruption in chronic inflammatory conditions. Skeletal growth as well as bone quality, physeal development, and vascularity were analyzed in C57BL6/J mice with plasminogen deficiency with and without deficiencies of either fibrinogen or IL-6. Elimination of fibrinogen, but not IL-6, rescued the skeletal phenotype and growth disturbances in this model of chronic disease. Furthermore, the skeletal phenotypes directly correlated with both systemic and local vascular changes in the skeletal environment. In conclusion, these results suggest that fibrinolysis through plasmin is essential for skeletal growth and maintenance, and is multifactorial by limiting inflammation and preserving vasculature.
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Affiliation(s)
- Heather A Cole
- Departments of Nuclear Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Stephanie N Moore-Lotridge
- Departments of Orthopaedics, Vanderbilt University Medical Center, Nashville, TN, United States.,Center of Bone Biology, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Gregory D Hawley
- Departments of Orthopaedics, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Richard Jacobson
- Departments of Orthopaedics, Vanderbilt University Medical Center, Nashville, TN, United States.,Department of Pharmacology, Vanderbilt University, Nashville, TN, United States
| | - Masato Yuasa
- Departments of Orthopaedics, Vanderbilt University Medical Center, Nashville, TN, United States.,Department of Orthopaedic and Spinal Surgery, Tokyo Medical and Dental University, Tokyo, Japan
| | - Leslie Gewin
- Departments of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States.,Department of Research, Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN, United States
| | - Jeffry S Nyman
- Departments of Orthopaedics, Vanderbilt University Medical Center, Nashville, TN, United States.,Center of Bone Biology, Vanderbilt University Medical Center, Nashville, TN, United States.,Department of Research, Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN, United States.,Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States
| | - Matthew J Flick
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, United States.,University of North Carolina Blood Research Center, University of North Carolina, Chapel Hill, NC, United States.,Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, United States
| | - Jonathan G Schoenecker
- Departments of Orthopaedics, Vanderbilt University Medical Center, Nashville, TN, United States.,Center of Bone Biology, Vanderbilt University Medical Center, Nashville, TN, United States.,Department of Pharmacology, Vanderbilt University, Nashville, TN, United States.,Departments of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States.,Departments of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States.,Departments of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, United States
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12
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Artunc F, Bohnert BN, Schneider JC, Staudner T, Sure F, Ilyaskin AV, Wörn M, Essigke D, Janessa A, Nielsen NV, Birkenfeld AL, Etscheid M, Haerteis S, Korbmacher C, Kanse SM. Proteolytic activation of the epithelial sodium channel (ENaC) by factor VII activating protease (FSAP) and its relevance for sodium retention in nephrotic mice. Pflugers Arch 2021; 474:217-229. [PMID: 34870751 PMCID: PMC8766372 DOI: 10.1007/s00424-021-02639-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/05/2021] [Accepted: 10/18/2021] [Indexed: 12/18/2022]
Abstract
Proteolytic activation of the epithelial sodium channel (ENaC) by aberrantly filtered serine proteases is thought to contribute to renal sodium retention in nephrotic syndrome. However, the identity of the responsible proteases remains elusive. This study evaluated factor VII activating protease (FSAP) as a candidate in this context. We analyzed FSAP in the urine of patients with nephrotic syndrome and nephrotic mice and investigated its ability to activate human ENaC expressed in Xenopus laevis oocytes. Moreover, we studied sodium retention in FSAP-deficient mice (Habp2−/−) with experimental nephrotic syndrome induced by doxorubicin. In urine samples from nephrotic humans, high concentrations of FSAP were detected both as zymogen and in its active state. Recombinant serine protease domain of FSAP stimulated ENaC-mediated whole-cell currents in a time- and concentration-dependent manner. Mutating the putative prostasin cleavage site in γ-ENaC (γRKRK178AAAA) prevented channel stimulation by the serine protease domain of FSAP. In a mouse model for nephrotic syndrome, active FSAP was present in nephrotic urine of Habp2+/+ but not of Habp2−/− mice. However, Habp2−/− mice were not protected from sodium retention compared to nephrotic Habp2+/+ mice. Western blot analysis revealed that in nephrotic Habp2−/− mice, proteolytic cleavage of α- and γ-ENaC was similar to that in nephrotic Habp2+/+ animals. In conclusion, active FSAP is excreted in the urine of nephrotic patients and mice and activates ENaC in vitro involving the putative prostasin cleavage site of γ-ENaC. However, endogenous FSAP is not essential for sodium retention in nephrotic mice.
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Affiliation(s)
- Ferruh Artunc
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany. .,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tubingen, Germany. .,German Center for Diabetes Research (DZD) at the University Tübingen, Tubingen, Germany.
| | - Bernhard N Bohnert
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tubingen, Germany.,German Center for Diabetes Research (DZD) at the University Tübingen, Tubingen, Germany
| | - Jonas C Schneider
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany
| | - Tobias Staudner
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Florian Sure
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Alexandr V Ilyaskin
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Matthias Wörn
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany
| | - Daniel Essigke
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tubingen, Germany.,German Center for Diabetes Research (DZD) at the University Tübingen, Tubingen, Germany
| | - Andrea Janessa
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany
| | - Nis V Nielsen
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Andreas L Birkenfeld
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tubingen, Germany.,German Center for Diabetes Research (DZD) at the University Tübingen, Tubingen, Germany
| | | | - Silke Haerteis
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany.,Institute of Anatomy, University of Regensburg, Regensburg, Germany
| | - Christoph Korbmacher
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Sandip M Kanse
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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13
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Bohnert BN, Essigke D, Janessa A, Schneider JC, Wörn M, Kalo MZ, Xiao M, Kong L, Omage K, Hennenlotter J, Amend B, Birkenfeld AL, Artunc F. Experimental nephrotic syndrome leads to proteolytic activation of the epithelial Na + channel in the mouse kidney. Am J Physiol Renal Physiol 2021; 321:F480-F493. [PMID: 34423678 DOI: 10.1152/ajprenal.00199.2021] [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] [Indexed: 11/22/2022] Open
Abstract
Proteolytic activation of the renal epithelial Na+ channel (ENaC) involves cleavage events in its α- and γ-subunits and is thought to mediate Na+ retention in nephrotic syndrome (NS). However, the detection of proteolytically processed ENaC in kidney tissue from nephrotic mice has been elusive so far. We used a refined Western blot technique to reliably discriminate full-length α-ENaC and γ-ENaC and their cleavage products after proteolysis at their proximal and distal cleavage sites (designated from the NH2-terminus), respectively. Proteolytic ENaC activation was investigated in kidneys from mice with experimental NS induced by doxorubicin or inducible podocin deficiency with or without treatment with the serine protease inhibitor aprotinin. Nephrotic mice developed Na+ retention and increased expression of fragments of α-ENaC and γ-ENaC cleaved at both the proximal cleavage site and, more prominently, the distal cleavage site, respectively. Treatment with aprotinin but not with the mineralocorticoid receptor antagonist canrenoate prevented Na+ retention and upregulation of the cleavage products in nephrotic mice. Increased expression of cleavage products of α-ENaC and γ-ENaC was similarly found in healthy mice treated with a low-salt diet, sensitive to mineralocorticoid receptor blockade. In human nephrectomy specimens, γ-ENaC was found in the full-length form and predominantly cleaved at its distal cleavage site. In conclusion, murine experimental NS leads to aprotinin-sensitive proteolytic activation of ENaC at both proximal and, more prominently, distal cleavage sites of its α- and γ-subunit, most likely by urinary serine protease activity or proteasuria.NEW & NOTEWORTHY This study demonstrates that murine experimental nephrotic syndrome leads to aprotinin-sensitive proteolytic activation of the epithelial Na+ channel at both the α- and γ-subunit, most likely by urinary serine protease activity or proteasuria.
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Affiliation(s)
- Bernhard N Bohnert
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, University Tübingen, Tübingen, Germany.,German Center for Diabetes Research, University Tübingen, Tübingen, Germany
| | - Daniel Essigke
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Andrea Janessa
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Jonas C Schneider
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Matthias Wörn
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - M Zaher Kalo
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Mengyun Xiao
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Lingsi Kong
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Kingsley Omage
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Jörg Hennenlotter
- Department of Urology, University Hospital Tübingen, Tübingen, Germany
| | - Bastian Amend
- Department of Urology, University Hospital Tübingen, Tübingen, Germany
| | - Andreas L Birkenfeld
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, University Tübingen, Tübingen, Germany.,German Center for Diabetes Research, University Tübingen, Tübingen, Germany
| | - Ferruh Artunc
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, University Tübingen, Tübingen, Germany.,German Center for Diabetes Research, University Tübingen, Tübingen, Germany
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14
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Bissinger R, Nemkov T, D'Alessandro A, Grau M, Dietz T, Bohnert BN, Essigke D, Wörn M, Schaefer L, Xiao M, Beirne JM, Kalo MZ, Schork A, Bakchoul T, Omage K, Kong L, Gonzalez-Menendez I, Quintanilla-Martinez L, Fehrenbacher B, Schaller M, Dhariwal A, Birkenfeld AL, Grahammer F, Qadri SM, Artunc F. Proteinuric chronic kidney disease is associated with altered red blood cell lifespan, deformability and metabolism. Kidney Int 2021; 100:1227-1239. [PMID: 34537228 DOI: 10.1016/j.kint.2021.08.024] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 08/05/2021] [Accepted: 08/13/2021] [Indexed: 12/14/2022]
Abstract
Anemia is a common complication of chronic kidney disease, affecting the quality of life of patients. Among various factors, such as iron and erythropoietin deficiency, reduced red blood cell (RBC) lifespan has been implicated in the pathogenesis of anemia. However, mechanistic data on in vivo RBC dysfunction in kidney disease are lacking. Herein, we describe the development of chronic kidney disease-associated anemia in mice with proteinuric kidney disease resulting from either administration of doxorubicin or an inducible podocin deficiency. In both experimental models, anemia manifested at day 10 and progressed at day 30 despite increased circulating erythropoietin levels and erythropoiesis in the bone marrow and spleen. Circulating RBCs in both mouse models displayed altered morphology and diminished osmotic-sensitive deformability together with increased phosphatidylserine externalization on the outer plasma membrane, a hallmark of RBC death. Fluorescence-labelling of RBCs at day 20 of mice with doxorubicin-induced kidney disease revealed premature clearance from the circulation. Metabolomic analyses of RBCs from both mouse models demonstrated temporal changes in redox recycling pathways and Lands' cycle, a membrane lipid remodeling process. Anemic patients with proteinuric kidney disease had an increased proportion of circulating phosphatidylserine-positive RBCs. Thus, our observations suggest that reduced RBC lifespan, mediated by altered RBC metabolism, reduced RBC deformability, and enhanced cell death contribute to the development of anemia in proteinuric kidney disease.
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Affiliation(s)
- Rosi Bissinger
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Travis Nemkov
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Angelo D'Alessandro
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA; Division of Hematology, University of Colorado Denver, Aurora, Colorado, USA
| | - Marijke Grau
- Institute of Molecular and Cellular Sports Medicine, German Sport University of Cologne, Köln, Germany
| | - Thomas Dietz
- Institute of Molecular and Cellular Sports Medicine, German Sport University of Cologne, Köln, Germany
| | - Bernhard N Bohnert
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany; Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD) at the University Tübingen, Tübingen, Germany
| | - Daniel Essigke
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Matthias Wörn
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Lina Schaefer
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Mengyun Xiao
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Jonathan M Beirne
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - M Zaher Kalo
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Anja Schork
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany; Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD) at the University Tübingen, Tübingen, Germany
| | - Tamam Bakchoul
- Center for Clinical Transfusion Medicine, University Hospital of Tübingen, Tübingen, Germany
| | - Kingsley Omage
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | - Lingsi Kong
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany
| | | | | | - Birgit Fehrenbacher
- Department of Dermatology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Martin Schaller
- Department of Dermatology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Achal Dhariwal
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Andreas L Birkenfeld
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany; Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD) at the University Tübingen, Tübingen, Germany
| | - Florian Grahammer
- Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Syed M Qadri
- Faculty of Health Sciences, Ontario Tech University, Oshawa, Ontario, Canada
| | - Ferruh Artunc
- Division of Endocrinology, Diabetology and Nephrology, Department of Internal Medicine, University Hospital Tübingen, Tübingen, Germany; Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD) at the University Tübingen, Tübingen, Germany.
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15
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Bohnert BN, Gonzalez-Menendez I, Dörffel T, Schneider JC, Xiao M, Janessa A, Kalo MZ, Fehrenbacher B, Schaller M, Casadei N, Amann K, Daniel C, Birkenfeld AL, Grahammer F, Izem L, Plow EF, Quintanilla-Martinez L, Artunc F. Essential role of DNA-PKcs and plasminogen for the development of doxorubicin-induced glomerular injury in mice. Dis Model Mech 2021; 14:271906. [PMID: 34423816 PMCID: PMC8461821 DOI: 10.1242/dmm.049038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 08/02/2021] [Indexed: 12/11/2022] Open
Abstract
Susceptibility to doxorubicin-induced nephropathy (DIN), a toxic model for the induction of proteinuria in mice, is related to the single-nucleotide polymorphism (SNP) C6418T of the Prkdc gene encoding for the DNA-repair enzyme DNA-PKcs. In addition, plasminogen (Plg) has been reported to play a role in glomerular damage. Here, we investigated the interdependence of both factors for the development of DIN. Genotyping confirmed the SNP of the Prkdc gene in C57BL/6 (PrkdcC6418/C6418) and 129S1/SvImJ (PrkdcT6418/T6418) mice. Intercross of heterozygous 129SB6F1 mice led to 129SB6F2 hybrids with Mendelian inheritance of the SNP. After doxorubicin injection, only homozygous F2 mice with PrkdcT6418/T6418 developed proteinuria. Genetic deficiency of Plg (Plg−/−) in otherwise susceptible 129S1/SvImJ mice led to resistance to DIN. Immunohistochemistry revealed glomerular binding of Plg in Plg+/+ mice after doxorubicin injection involving histone H2B as Plg receptor. In doxorubicin-resistant C57BL/6 mice, Plg binding was absent. In conclusion, susceptibility to DIN in 129S1/SvImJ mice is determined by a hierarchical two-hit process requiring the C6418T SNP in the Prkdc gene and subsequent glomerular binding of Plg. This article has an associated First Person interview with the first author of the paper. Summary: Susceptibility to doxorubicin-induced nephropathy in 129S1/SvImJ mice is determined by a hierarchical two-hit process requiring the C6418T single-nucleotide polymorphism in the Prkdc gene and subsequent glomerular binding of plasminogen.
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Affiliation(s)
- Bernhard N Bohnert
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, 72076 Tübingen, Germany.,German Center for Diabetes Research (DZD), University Tübingen, 72076 Tübingen, Germany
| | - Irene Gonzalez-Menendez
- Institute of Pathology and Neuropathology, Department of Pathology, Eberhard Karls University of Tübingen and Comprehensive Cancer Center, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Thomas Dörffel
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Jonas C Schneider
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Mengyun Xiao
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Andrea Janessa
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany
| | - M Zaher Kalo
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Birgit Fehrenbacher
- Department of Dermatology, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Martin Schaller
- Department of Dermatology, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Nicolas Casadei
- Institute of Genetics, University Hospital Tübingen, 72076 Tübingen, Germany.,NGS Competence Center Tübingen, University Tübingen, Tübingen 72076, Germany
| | - Kerstin Amann
- Institute of Pathology, Department of Nephropathology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Christoph Daniel
- Institute of Pathology, Department of Nephropathology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Andreas L Birkenfeld
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, 72076 Tübingen, Germany.,German Center for Diabetes Research (DZD), University Tübingen, 72076 Tübingen, Germany
| | - Florian Grahammer
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Lahoucine Izem
- Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Edward F Plow
- Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Leticia Quintanilla-Martinez
- Institute of Pathology and Neuropathology, Department of Pathology, Eberhard Karls University of Tübingen and Comprehensive Cancer Center, University Hospital Tübingen, 72076 Tübingen, Germany
| | - Ferruh Artunc
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, 72076 Tübingen, Germany.,German Center for Diabetes Research (DZD), University Tübingen, 72076 Tübingen, Germany
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16
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Essigke D, Ilyaskin AV, Wörn M, Bohnert BN, Xiao M, Daniel C, Amann K, Birkenfeld AL, Szabo R, Bugge TH, Korbmacher C, Artunc F. Zymogen-locked mutant prostasin (Prss8) leads to incomplete proteolytic activation of the epithelial sodium channel (ENaC) and severely compromises triamterene tolerance in mice. Acta Physiol (Oxf) 2021; 232:e13640. [PMID: 33650216 DOI: 10.1111/apha.13640] [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] [Received: 11/18/2020] [Revised: 02/15/2021] [Accepted: 02/26/2021] [Indexed: 02/06/2023]
Abstract
AIM The serine protease prostasin (Prss8) is expressed in the distal tubule and stimulates proteolytic activation of the epithelial sodium channel (ENaC) in co-expression experiments in vitro. The aim of this study was to explore the role of prostasin in proteolytic ENaC activation in the kidney in vivo. METHODS We used genetically modified knockin mice carrying a Prss8 mutation abolishing proteolytic activity (Prss8-S238A) or a mutation leading to a zymogen-locked state (Prss8-R44Q). Mice were challenged with low sodium diet and diuretics. Regulation of ENaC activity by Prss8-S238A and Prss8-R44Q was studied in vitro using the Xenopus laevis oocyte expression system. RESULTS Co-expression of murine ENaC with Prss8-wt or Prss8-S238A in oocytes caused maximal proteolytic ENaC activation, whereas ENaC was activated only partially in oocytes co-expressing Prss8-R44Q. This was paralleled by a reduced proteolytic activity at the cell surface of Prss8-R44Q expressing oocytes. Sodium conservation under low sodium diet was preserved in Prss8-S238A and Prss8-R44Q mice but with higher plasma aldosterone concentrations in Prss8-R44Q mice. Treatment with the ENaC inhibitor triamterene over four days was tolerated in Prss8-wt and Prss8-S238A mice, whereas Prss8-R44Q mice developed salt wasting and severe weight loss associated with hyperkalemia and acidosis consistent with impaired ENaC function and renal failure. CONCLUSION Unlike proteolytically inactive Prss8-S238A, zymogen-locked Prss8-R44Q produces incomplete proteolytic ENaC activation in vitro and causes a severe renal phenotype in mice treated with the ENaC inhibitor triamterene. This indicates that Prss8 plays a role in proteolytic ENaC activation and renal function independent of its proteolytic activity.
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Affiliation(s)
- Daniel Essigke
- Department of Internal Medicine Division of Endocrinology, Diabetology and Nephrology University Hospital Tübingen Tuebingen Germany
| | - Alexandr V. Ilyaskin
- Institute of Cellular and Molecular Physiology Friedrich‐Alexander University Erlangen‐Nürnberg (FAU) Erlangen Germany
| | - Matthias Wörn
- Department of Internal Medicine Division of Endocrinology, Diabetology and Nephrology University Hospital Tübingen Tuebingen Germany
| | - Bernhard N. Bohnert
- Department of Internal Medicine Division of Endocrinology, Diabetology and Nephrology University Hospital Tübingen Tuebingen Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen Tuebingen Germany
- German Center for Diabetes Research (DZD) at the University Tübingen Tuebingen Germany
| | - Mengyun Xiao
- Department of Internal Medicine Division of Endocrinology, Diabetology and Nephrology University Hospital Tübingen Tuebingen Germany
| | - Christoph Daniel
- Institute of Pathology Department of Nephropathology Friedrich‐Alexander University Erlangen‐Nürnberg (FAU) Erlangen Germany
| | - Kerstin Amann
- Institute of Pathology Department of Nephropathology Friedrich‐Alexander University Erlangen‐Nürnberg (FAU) Erlangen Germany
| | - Andreas L. Birkenfeld
- Department of Internal Medicine Division of Endocrinology, Diabetology and Nephrology University Hospital Tübingen Tuebingen Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen Tuebingen Germany
- German Center for Diabetes Research (DZD) at the University Tübingen Tuebingen Germany
| | - Roman Szabo
- Proteases and Tissue Remodeling Section National Institute of Dental and Craniofacial ResearchNational Institutes of Health Bethesda MD USA
| | - Thomas H. Bugge
- Proteases and Tissue Remodeling Section National Institute of Dental and Craniofacial ResearchNational Institutes of Health Bethesda MD USA
| | - Christoph Korbmacher
- Institute of Cellular and Molecular Physiology Friedrich‐Alexander University Erlangen‐Nürnberg (FAU) Erlangen Germany
| | - Ferruh Artunc
- Department of Internal Medicine Division of Endocrinology, Diabetology and Nephrology University Hospital Tübingen Tuebingen Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen Tuebingen Germany
- German Center for Diabetes Research (DZD) at the University Tübingen Tuebingen Germany
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17
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Affiliation(s)
- Isabel Auge
- Experimentelle Nephrologie Universitätsklinikum Jena Jena Germany
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18
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Frindt G, Shi S, Kleyman TR, Palmer LG. Cleavage state of γENaC in mouse and rat kidneys. Am J Physiol Renal Physiol 2021; 320:F485-F491. [PMID: 33522411 DOI: 10.1152/ajprenal.00536.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Extracellular proteases can activate the epithelial Na channel (ENaC) by cleavage of the γ subunit. Here, we investigated the cleavage state of the channel in the kidneys of mice and rats on a low-salt diet. We identified the cleaved species of channels expressed in Fisher rat thyroid cells by coexpressing the apical membrane-bound protease channel-activating protease 1 (CAP1; prostasin). To compare the peptides produced in the heterologous system with those in the mouse kidney, we treated both lysates with PNGaseF to remove N-linked glycosylation. The apparent molecular mass of the smallest COOH-terminal fragment of γENaC (52 kDa) was indistinguishable from that of the CAP1-induced species in Fisher rat thyroid cells. Similar cleaved peptides were observed in total and cell surface fractions of the rat kidney. This outcome suggests that most of the subunits at the surface have been processed by extracellular proteases. This was confirmed using nonreducing gels, in which the NH2- and COOH-terminal fragments of γENaC are linked by a disulfide bond. Under these conditions, the major cleaved form in the rat kidney had an apparent molecular mass of 56 kDa, ∼4 kDa lower than that of the full-length form, consistent with excision of a short peptide by two proteolytic events. We conclude that the most abundant γENaC species in the apical membrane of rat and mouse kidneys on a low-Na diet is the twice-cleaved, presumably activated form.NEW & NOTEWORTHY We have identified the major aldosterone-dependent cleaved form of the epithelial Na channel (ENaC) γ subunit in the kidney as a twice-cleaved peptide. This form appears to be identical in size with a subunit cleaved in vitro by the extracellular protease channel-activating protease 1 (prostasin). In the absence of reducing agents, it has an overall molecular mass less than that of the intact subunit, consistent with the excision of an inhibitory domain.
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Affiliation(s)
- Gustavo Frindt
- Department of Physiology and Biophysics, Weill Cornell School of Medicine, New York, New York
| | - Shujie Shi
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Thomas R Kleyman
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.,Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.,Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Lawrence G Palmer
- Department of Physiology and Biophysics, Weill Cornell School of Medicine, New York, New York
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