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Bockenhauer D, Kleta R. Tubulopathy meets Sherlock Holmes: biochemical fingerprinting of disorders of altered kidney tubular salt handling. Pediatr Nephrol 2021; 36:2553-2561. [PMID: 34143300 PMCID: PMC8260524 DOI: 10.1007/s00467-021-05098-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 04/27/2021] [Indexed: 11/19/2022]
Abstract
Evolution moves in mysterious ways. Excretion of waste products by glomerular filtration made perfect sense when life evolved in the ocean. Yet, the associated loss of water and solutes became a problem when life moved onto land: a serious design change was needed and this occurred in the form of ever more powerful tubules that attached to the glomerulus. By reabsorbing typically more than 99% of the glomerular filtrate, the tubules not only minimise urinary losses, but, crucially, also maintain homeostasis: tubular reabsorption and secretion are adjusted so as to maintain an overall balance, in which urine volume and composition matches intake and environmental stressors. A whole orchestra of highly specialised tubular transport proteins is involved in this process and dysfunction of one or more of these results in the so-called kidney tubulopathies, characterised by specific patterns of clinical and biochemical abnormalities. In turn, recognition of these patterns helps establish a specific diagnosis and pinpoints the defective transport pathway. In this review, we will discuss these clinical and biochemical "fingerprints" of tubular disorders of salt-handling and how sodium handling affects volume homeostasis but also handling of other solutes.
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Affiliation(s)
- Detlef Bockenhauer
- Department of Renal Medicine, University College London, NW3 2PF, London, UK. .,Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK.
| | - Robert Kleta
- Department of Renal Medicine, University College London, NW3 2PF, London, UK.,Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
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52
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Mayes-Hopfinger L, Enache A, Xie J, Huang CL, Köchl R, Tybulewicz VLJ, Fernandes-Alnemri T, Alnemri ES. Chloride sensing by WNK1 regulates NLRP3 inflammasome activation and pyroptosis. Nat Commun 2021; 12:4546. [PMID: 34315884 PMCID: PMC8316491 DOI: 10.1038/s41467-021-24784-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 06/30/2021] [Indexed: 01/05/2023] Open
Abstract
The NLRP3 inflammasome mediates the production of proinflammatory cytokines and initiates inflammatory cell death. Although NLRP3 is essential for innate immunity, aberrant NLRP3 inflammasome activation contributes to a wide variety of inflammatory diseases. Understanding the pathways that control NLRP3 activation will help develop strategies to treat these diseases. Here we identify WNK1 as a negative regulator of the NLRP3 inflammasome. Macrophages deficient in WNK1 protein or kinase activity have increased NLRP3 activation and pyroptosis compared with control macrophages. Mice with conditional knockout of WNK1 in macrophages have increased IL-1β production in response to NLRP3 stimulation compared with control mice. Mechanistically, WNK1 tempers NLRP3 activation by balancing intracellular Cl- and K+ concentrations during NLRP3 activation. Collectively, this work shows that the WNK1 pathway has a critical function in suppressing NLRP3 activation and suggests that pharmacological inhibition of this pathway to treat hypertension might have negative clinical implications.
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Affiliation(s)
- Lindsey Mayes-Hopfinger
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Aura Enache
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Jian Xie
- Department of Medicine, Division of Nephrology, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - Chou-Long Huang
- Department of Medicine, Division of Nephrology, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - Robert Köchl
- The Francis Crick Institute, London, UK
- Kings College London, London, UK
| | | | - Teresa Fernandes-Alnemri
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Emad S Alnemri
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA.
- Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA.
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53
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Xiao Y, Duan XP, Zhang DD, Wang WH, Lin DH. Deletion of renal Nedd4-2 abolishes the effect of high K + intake on Kir4.1/Kir5.1 and NCC activity in the distal convoluted tubule. Am J Physiol Renal Physiol 2021; 321:F1-F11. [PMID: 34029145 DOI: 10.1152/ajprenal.00072.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
High-dietary K+ (HK) intake inhibits basolateral Kir4.1/Kir5.1 activity in the distal convoluted tubule (DCT), and HK-induced inhibition of Kir4.1/Kir5.1 is essential for HK-induced inhibition of NaCl cotransporter (NCC). Here, we examined whether neural precursor cell expressed developmentally downregulated 4-2 (Nedd4-2) deletion compromises the effect of HK on basolateral Kir4.1/Kir5.1 and NCC in the DCT. Single-channel recording and whole cell recording showed that neither HK decreased nor low-dietary K+ (LK) increased basolateral Kir4.1/Kir5.1 activity of the DCT in kidney tubule-specific Nedd4-2 knockout (Ks-Nedd4-2 KO) mice. In contrast, HK inhibited and LK increased Kir4.1/Kir5.1 activity in control mice [neural precursor cell expressed developmentally downregulated 4-like (Nedd4l)flox/flox]. Also, HK intake decreased the negativity of K+ current reversal potential in the DCT (depolarization) only in control mice but not in Ks-Nedd4-2 KO mice. Renal clearance experiments showed that HK intake decreased, whereas LK intake increased, hydrochlorothiazide-induced renal Na+ excretion only in control mice, but this effect was absent in Ks-Nedd4-2 KO mice. Western blot analysis also demonstrated that HK-induced inhibition of phosphorylated NCC (Thr53) and total NCC was observed only in control mice but not in Ks-Nedd4-2 KO mice. Furthermore, expression of all three subunits of the epithelial Na+ channel in Ks-Nedd4-2 KO mice on HK was higher than in control mice. Thus, plasma K+ concentrations were similar between Nedd4lflox/flox and Ks-Nedd4-2 KO mice on HK for 7 days despite high NCC expression. We conclude that Nedd4-2 plays a role in regulating HK-induced inhibition of Kir4.1/Kir5.1 and NCC in the DCT.NEW & NOTEWORTHY Basolateral Kir4.1/Kir5.1 in the distal convoluted tubule plays an important role as a "K+ sensor" in the regulation of renal K+ excretion after high K+ intake. We found that neural precursor cell expressed developmentally downregulated 4-2 (Nedd4-2) a role in mediating the effect of K+ diet on Kir4.1/Kir5.1 and NaCl cotransporter because high K+ intake failed to inhibit basolateral Kir4.1/Kir5.1 and NaCl cotransporter in kidney tubule-specific Nedd4-2 knockout mice.
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Affiliation(s)
- Yu Xiao
- Department of Physiology, Qiqihar Medical College, Heilongjiang, China.,Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Xin-Peng Duan
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dan-Dan Zhang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York
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54
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Mukherjee A, Yang CL, McCormick JA, Martz K, Sharma A, Ellison DH. Roles of WNK4 and SPAK in K +-mediated dephosphorylation of the NaCl cotransporter. Am J Physiol Renal Physiol 2021; 320:F719-F733. [PMID: 33719576 PMCID: PMC8174808 DOI: 10.1152/ajprenal.00459.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 03/02/2021] [Accepted: 03/03/2021] [Indexed: 02/06/2023] Open
Abstract
Phosphorylation of the thiazide-sensitive NaCl cotransporter (NCC) in the distal convoluted tubule (DCT) is altered rapidly in response to changes in extracellular K+ concentration ([K+]). High extracellular [K+] is believed to activate specific phosphatases to dephosphorylate NCC, thereby reducing its activity. This process is defective in the human disease familial hyperkalemic hypertension, in which extracellular [K+] fails to dephosphorylate NCC, suggesting an interplay between NCC-activating and NCC-inactivating switches. Here, we explored the role of STE20/SPS1-related proline-alanine-rich protein kinase (SPAK) and intracellular Cl- concentration in the rapid effects of extracellular K+ on NCC phosphorylation. SPAK was found to be rapidly dephosphorylated in vitro in human embryonic kidney cells and ex vivo in kidney slices by high [K+]. Acute high-K+ challenge resulted in DCT1-specific SPAK dephosphorylation in vivo and dissolution of SPAK puncta. In line with the postulate of interplay between activating and inactivating switches, we found that the "on" switch, represented by with no lysine kinase 4 (WNK4)-SPAK, must be turned off for rapid NCC dephosphorylation by high [K+]. Longer-term WNK-SPAK-mediated stimulation, however, altered the sensitivity of the system, as it attenuated rapid NCC dephosphorylation due to acute K+ loading. Although blockade of protein phosphatase (PP)1 increased NCC phosphorylation at baseline, neither PP1 nor PP3, singly or in combination, was essential for NCC dephosphorylation. Overall, our data suggest that NCC phosphorylation is regulated by a dynamic equilibrium between activating kinases and inactivating phosphatases, with kinase inactivation playing a key role in the rapid NCC dephosphorylation by high extracellular K+.NEW & NOTEWORTHY Although a great deal is known about mechanisms by which thiazide-sensitive NaCl cotransporter is phosphorylated and activated, much less is known about dephosphorylation. Here, we show that rapid dephosphorylation by high K+ depends on the Cl- sensitivity of with no lysine kinase 4 and the rapid dephosphorylation of STE20/SPS1-related proline-alanine-rich protein kinase, primarily along the early distal convoluted tubule.
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Affiliation(s)
- Anindit Mukherjee
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Chao-Ling Yang
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - James A McCormick
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Kevin Martz
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Avika Sharma
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
- Oregon Clinical and Translational Research Institute, Oregon Health and Science University, Portland, Oregon
- Veterans Affairs Portland Health Care System, Portland, Oregon
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55
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Ostrosky-Frid M, Chávez-Canales M, Zhang J, Andrukhova O, Argaiz ER, Lerdo-de-Tejada F, Murillo-de-Ozores A, Sanchez-Navarro A, Rojas-Vega L, Bobadilla NA, Vazquez N, Castañeda-Bueno M, Alessi DR, Gamba G. Role of KLHL3 and dietary K + in regulating KS-WNK1 expression. Am J Physiol Renal Physiol 2021; 320:F734-F747. [PMID: 33682442 PMCID: PMC8174809 DOI: 10.1152/ajprenal.00575.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 03/03/2021] [Accepted: 03/03/2021] [Indexed: 02/08/2023] Open
Abstract
The physiological role of the shorter isoform of with no lysine kinase (WNK)1 that is exclusively expressed in the kidney (KS-WNK1), with particular abundance in the distal convoluted tubule, remains elusive. KS-WNK1, despite lacking the kinase domain, is nevertheless capable of stimulating the NaCl cotransporter, apparently through activation of WNK4. It has recently been shown that a less severe form of familial hyperkalemic hypertension featuring only hyperkalemia is caused by missense mutations in the WNK1 acidic domain that preferentially affect cullin 3 (CUL3)-Kelch-like protein 3 (KLHL3) E3-induced degradation of KS-WNK1 rather than that of full-length WNK1. Here, we show that full-length WNK1 is indeed less impacted by the CUL3-KLHL3 E3 ligase complex compared with KS-WNK1. We demonstrated that the unique 30-amino acid NH2-terminal fragment of KS-WNK1 is essential for its activating effect on the NaCl cotransporter and recognition by KLHL3. We identified specific amino acid residues in this region critical for the functional effect of KS-WNK1 and KLHL3 sensitivity. To further explore this, we generated KLHL3-R528H knockin mice that mimic human mutations causing familial hyperkalemic hypertension. These mice revealed that the KLHL3 mutation specifically increased expression of KS-WNK1 in the kidney. We also observed that in wild-type mice, the expression of KS-WNK1 was only detectable after exposure to a low-K+ diet. These findings provide new insights into the regulation and function of KS-WNK1 by the CUL3-KLHL3 complex in the distal convoluted tubule and indicate that this pathway is regulated by dietary K+ levels.NEW & NOTEWORTHY In this work, we demonstrated that the kidney-specific isoform of with no lysine kinase 1 (KS-WNK1) in the kidney is modulated by dietary K+ and activity of the ubiquitin ligase protein Kelch-like protein 3. We analyzed the role of different amino acid residues of KS-WNK1 in its activity against the NaCl cotransporter and sensitivity to Kelch-like protein 3.
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Affiliation(s)
- Mauricio Ostrosky-Frid
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
- PECEM (MD/PhD), Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - María Chávez-Canales
- Unidad de Investigación UNAM-INC, Instituto Nacional de Cardiología Ignacio Chávez and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Jinwei Zhang
- Institute of Biomedical and Clinical Sciences, Medical School, College of Medicine and Health, University of Exeter, Hatherly Laboratories, Exeter, United Kingdom
| | - Olena Andrukhova
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Eduardo R Argaiz
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Fernando Lerdo-de-Tejada
- Unidad de Investigación UNAM-INC, Instituto Nacional de Cardiología Ignacio Chávez and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Adrian Murillo-de-Ozores
- Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Andrea Sanchez-Navarro
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Lorena Rojas-Vega
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Norma A Bobadilla
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Norma Vazquez
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - María Castañeda-Bueno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Dario R Alessi
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Gerardo Gamba
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
- PECEM (MD/PhD), Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
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56
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Meor Azlan NF, Koeners MP, Zhang J. Regulatory control of the Na-Cl co-transporter NCC and its therapeutic potential for hypertension. Acta Pharm Sin B 2021; 11:1117-1128. [PMID: 34094823 PMCID: PMC8144889 DOI: 10.1016/j.apsb.2020.09.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 08/28/2020] [Accepted: 08/31/2020] [Indexed: 02/08/2023] Open
Abstract
Hypertension is the largest risk factor for cardiovascular disease, the leading cause of mortality worldwide. As blood pressure regulation is influenced by multiple physiological systems, hypertension cannot be attributed to a single identifiable etiology. Three decades of research into Mendelian forms of hypertension implicated alterations in the renal tubular sodium handling, particularly the distal convoluted tubule (DCT)-native, thiazide-sensitive Na-Cl cotransporter (NCC). Altered functions of the NCC have shown to have profound effects on blood pressure regulation as illustrated by the over activation and inactivation of the NCC in Gordon's and Gitelman syndromes respectively. Substantial progress has uncovered multiple factors that affect the expression and activity of the NCC. In particular, NCC activity is controlled by phosphorylation/dephosphorylation, and NCC expression is facilitated by glycosylation and negatively regulated by ubiquitination. Studies have even found parvalbumin to be an unexpected regulator of the NCC. In recent years, there have been considerable advances in our understanding of NCC control mechanisms, particularly via the pathway containing the with-no-lysine [K] (WNK) and its downstream target kinases, SPS/Ste20-related proline-alanine-rich kinase (SPAK) and oxidative stress responsive 1 (OSR1), which has led to the discovery of novel inhibitory molecules. This review summarizes the currently reported regulatory mechanisms of the NCC and discusses their potential as therapeutic targets for treating hypertension.
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Key Words
- ATP, adenosine triphosphate
- Blood pressure regulation
- CCC, cation-coupled chloride cotransporters
- CCT, conserved carboxy-terminal
- CNI, calcineurin inhibitors
- CUL3, cullin 3
- CUL3/KLHL3-WNK-SPAK/OSR1
- Ca2+, calcium ion
- Cardiovascular disease
- DAG, diacylglycerol
- DCT, distal convoluted tubule
- DUSP, dual specificity phosphatases
- ECF, extracellular fluid
- ELISA, enzyme-bound immunosorbent analysis
- ERK, extracellular signal-regulated kinases
- EnaC, epithelial sodium channels
- GABA, gamma-aminobutyric acid
- HEK293, human embryonic kidney 293
- Hypertension
- I1, inhibitor 1
- K+, potassium ion
- KCC, potassium-chloride-cotransporters
- KLHL3, kelch-like 3
- KS-WNK1, kidney specific-WNK1
- Kinase inhibitors
- MAPK, mitogen-activated protein kinase
- MO25, mouse protein-25
- Membrane trafficking
- NCC, sodium–chloride cotransporters
- NKCC, sodium–potassium–chloride-cotransporter
- Na+, sodium ion
- NaCl, sodium chloride
- NaCl-cotransporter NCC
- OSR1, oxidative stress-responsive gene 1
- PCT, proximal convoluted tubule
- PHAII, pseudohypoaldosteronism type II
- PP, protein phosphatase
- PV, parvalbumin
- ROMK, renal outer medullary potassium
- RasGRP1, RAS guanyl-releasing protein 1
- SLC12, solute carrier 12
- SPAK, Ste20-related proline-alanine-rich-kinase
- TAL, thick ascending limb
- Therapeutic targets
- WNK, with-no-lysine kinases
- mDCT, mammalian DCT
- mRNA, messenger RNA
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Murillo-de-Ozores AR, Rodríguez-Gama A, Carbajal-Contreras H, Gamba G, Castañeda-Bueno M. WNK4 kinase: from structure to physiology. Am J Physiol Renal Physiol 2021; 320:F378-F403. [PMID: 33491560 DOI: 10.1152/ajprenal.00634.2020] [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] [Indexed: 12/12/2022] Open
Abstract
With no lysine kinase-4 (WNK4) belongs to a serine-threonine kinase family characterized by the atypical positioning of its catalytic lysine. Despite the fact that WNK4 has been found in many tissues, the majority of its study has revolved around its function in the kidney, specifically as a positive regulator of the thiazide-sensitive NaCl cotransporter (NCC) in the distal convoluted tubule of the nephron. This is explained by the description of gain-of-function mutations in the gene encoding WNK4 that causes familial hyperkalemic hypertension. This disease is mainly driven by increased downstream activation of the Ste20/SPS1-related proline-alanine-rich kinase/oxidative stress responsive kinase-1-NCC pathway, which increases salt reabsorption in the distal convoluted tubule and indirectly impairs renal K+ secretion. Here, we review the large volume of information that has accumulated about different aspects of WNK4 function. We first review the knowledge on WNK4 structure and enumerate the functional domains and motifs that have been characterized. Then, we discuss WNK4 physiological functions based on the information obtained from in vitro studies and from a diverse set of genetically modified mouse models with altered WNK4 function. We then review in vitro and in vivo evidence on the different levels of regulation of WNK4. Finally, we go through the evidence that has suggested how different physiological conditions act through WNK4 to modulate NCC activity.
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Affiliation(s)
- Adrián Rafael Murillo-de-Ozores
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico.,Facultad de Medicina, Universidad Nacional Autónoma de México, Coyoacan, Mexico City, Mexico
| | | | - Héctor Carbajal-Contreras
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico.,Combined Studies Program in Medicine MD/PhD (PECEM), Facultad de Medicina, Universidad Nacional Autónoma de México, Coyoacan, Mexico City, Mexico, Mexico
| | - Gerardo Gamba
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico.,Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico.,Combined Studies Program in Medicine MD/PhD (PECEM), Facultad de Medicina, Universidad Nacional Autónoma de México, Coyoacan, Mexico City, Mexico, Mexico
| | - María Castañeda-Bueno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico.,Combined Studies Program in Medicine MD/PhD (PECEM), Facultad de Medicina, Universidad Nacional Autónoma de México, Coyoacan, Mexico City, Mexico, Mexico
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58
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Chan CH, Wu SN, Bao BY, Li HW, Lu TL. MST3 Involvement in Na + and K + Homeostasis with Increasing Dietary Potassium Intake. Int J Mol Sci 2021; 22:ijms22030999. [PMID: 33498219 PMCID: PMC7863938 DOI: 10.3390/ijms22030999] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/14/2021] [Accepted: 01/15/2021] [Indexed: 02/07/2023] Open
Abstract
K+ loading inhibits NKCC2 (Na-K-Cl cotransporter) and NCC (Na-Cl cotransporter) in the early distal tubules, resulting in Na+ delivery to the late distal convoluted tubules (DCTs). In the DCTs, Na+ entry through ENaC (epithelial Na channel) drives K+ secretion through ROMK (renal outer medullary potassium channel). WNK4 (with-no-lysine 4) regulates the NCC/NKCC2 through SAPK (Ste20-related proline-alanine-rich kinase)/OSR1 (oxidative stress responsive). K+ loading increases intracellular Cl−, which binds to the WNK4, thereby inhibiting autophosphorylation and downstream signals. Acute K+ loading-deactivated NCC was not observed in Cl−-insensitive WNK4 mice, indicating that WNK4 was involved in K+ loading-inhibited NCC activity. However, chronic K+ loading deactivated NCC in Cl−-insensitive WNK4 mice, indicating that other mechanisms may be involved. We previously reported that mammalian Ste20-like protein kinase 3 (MST3/STK24) was expressed mainly in the medullary TAL (thick ascending tubule) and at lower levels in the DCTs. MST3−/− mice exhibited higher ENaC activity, causing hypernatremia and hypertension. To investigate MST3 function in maintaining Na+/K+ homeostasis in kidneys, mice were fed diets containing various concentrations of Na+ and K+. The 2% KCl diets induced less MST3 expression in MST3−/− mice than that in wild-type (WT) mice. The MST3−/− mice had higher WNK4, NKCC2-S130 phosphorylation, and ENaC expression, resulting in lower urinary Na+ and K+ excretion than those of WT mice. Lower urinary Na+ excretion was associated with elevated plasma [Na+] and hypertension. These results suggest that MST3 maintains Na+/K+ homeostasis in response to K+ loading by regulation of WNK4 expression and NKCC2 and ENaC activity.
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Affiliation(s)
- Chee-Hong Chan
- Department of Nephrology, Chang Bing Show Chwan Memorial Hospital, Lukang, Changhua 505, Taiwan;
| | - Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, Tainan 70101, Taiwan;
| | - Bo-Ying Bao
- School of Pharmacy, China Medical University, Taichung 406040, Taiwan;
- Department of Nursing, Asia University, Taichung 41354, Taiwan
| | - Houng-Wei Li
- Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung 406040, Taiwan;
| | - Te-Ling Lu
- School of Pharmacy, China Medical University, Taichung 406040, Taiwan;
- Correspondence:
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59
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Pleinis JM, Norrell L, Akella R, Humphreys JM, He H, Sun Q, Zhang F, Sosa-Pagan J, Morrison DE, Schellinger JN, Jackson LK, Goldsmith EJ, Rodan AR. WNKs are potassium-sensitive kinases. Am J Physiol Cell Physiol 2021; 320:C703-C721. [PMID: 33439774 DOI: 10.1152/ajpcell.00456.2020] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
With no lysine (K) (WNK) kinases regulate epithelial ion transport in the kidney to maintain homeostasis of electrolyte concentrations and blood pressure. Chloride ion directly binds WNK kinases to inhibit autophosphorylation and activation. Changes in extracellular potassium are thought to regulate WNKs through changes in intracellular chloride. Prior studies demonstrate that in some distal nephron epithelial cells, intracellular potassium changes with chronic low- or high-potassium diet. We, therefore, investigated whether potassium regulates WNK activity independent of chloride. We found decreased activity of Drosophila WNK and mammalian WNK3 and WNK4 in fly Malpighian (renal) tubules bathed in high extracellular potassium, even when intracellular chloride was kept constant at either ∼13 mM or 26 mM. High extracellular potassium also inhibited chloride-insensitive mutants of WNK3 and WNK4. High extracellular rubidium was also inhibitory and increased tubule rubidium. The Na+/K+-ATPase inhibitor, ouabain, which is expected to lower intracellular potassium, increased tubule Drosophila WNK activity. In vitro, potassium increased the melting temperature of Drosophila WNK, WNK1, and WNK3 kinase domains, indicating ion binding to the kinase. Potassium inhibited in vitro autophosphorylation of Drosophila WNK and WNK3, and also inhibited WNK3 and WNK4 phosphorylation of their substrate, Ste20-related proline/alanine-rich kinase (SPAK). The greatest sensitivity of WNK4 to potassium occurred in the range of 80-180 mM, encompassing physiological intracellular potassium concentrations. Together, these data indicate chloride-independent potassium inhibition of Drosophila and mammalian WNK kinases through direct effects of potassium ion on the kinase.
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Affiliation(s)
- John M Pleinis
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah
| | - Logan Norrell
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah
| | - Radha Akella
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas
| | - John M Humphreys
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Haixia He
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Qifei Sun
- Division of Nephrology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Feng Zhang
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah
| | - Jason Sosa-Pagan
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah
| | - Daryl E Morrison
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah
| | - Jeffrey N Schellinger
- Division of Nephrology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | | | - Elizabeth J Goldsmith
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Aylin R Rodan
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah.,Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, Utah.,Department of Human Genetics, University of Utah, Salt Lake City, Utah.,Medical Service, Veterans Affairs Salt Lake City Health Care System, Salt Lake City, Utah
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60
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Ayasse N, Berg P, Leipziger J, Sørensen MV. ENaC expression correlates with the acute furosemide-induced K + excretion. Physiol Rep 2021; 9:e14668. [PMID: 33410279 PMCID: PMC7788322 DOI: 10.14814/phy2.14668] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 10/27/2020] [Accepted: 10/28/2020] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND In the aldosterone-sensitive distal nephron (ASDN), epithelial sodium channel (ENaC)-mediated Na+ absorption drives K+ excretion. K+ excretion depends on the delivery of Na+ to the ASDN and molecularly activated ENaC. Furosemide is known as a K+ wasting diuretic as it greatly enhances Na+ delivery to the ASDN. Here, we studied the magnitude of acute furosemide-induced kaliuresis under various states of basal molecular ENaC activity. METHODS C57/Bl6J mice were subjected to different dietary regimens that regulate molecular ENaC expression and activity levels. The animals were anesthetized and bladder-catheterized. Diuresis was continuously measured before and after administration of furosemide (2 µg/g BW) or benzamil (0.2 µg/g BW). Flame photometry was used to measure urinary [Na+ ] and [K+ ]. The kidneys were harvested and, subsequently, ENaC expression and cleavage activation were determined by semiquantitative western blotting. RESULTS A low K+ and a high Na+ diet markedly suppressed ENaC protein expression, cleavage activation, and furosemide-induced kaliuresis. In contrast, furosemide-induced kaliuresis was greatly enhanced in animals fed a high K+ or low Na+ diet, conditions with increased ENaC expression. The furosemide-induced diuresis was similar in all dietary groups. CONCLUSION Acute furosemide-induced kaliuresis differs greatly and depends on the a priori molecular expression level of ENaC. Remarkably, it can be even absent in animals fed a high Na+ diet, despite a marked increase of tubular flow and urinary Na+ excretion. This study provides auxiliary evidence that acute ENaC-dependent K+ excretion requires both Na+ as substrate and molecular activation of ENaC.
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Affiliation(s)
- Niklas Ayasse
- Department of Biomedicine, PhysiologyAarhus UniversityAarhus CDenmark
| | - Peder Berg
- Department of Biomedicine, PhysiologyAarhus UniversityAarhus CDenmark
| | - Jens Leipziger
- Department of Biomedicine, PhysiologyAarhus UniversityAarhus CDenmark
- Aarhus Institute of Advanced StudiesAarhus UniversityAarhus CDenmark
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61
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Xu S, Li J, Yang L, Wang CJ, Liu T, Weinstein AM, Palmer LG, Wang T. Sex difference in kidney electrolyte transport III: Impact of low K intake on thiazide-sensitive cation excretion in male and female mice. Pflugers Arch 2021; 473:1749-1760. [PMID: 34455480 PMCID: PMC8528772 DOI: 10.1007/s00424-021-02611-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/15/2021] [Accepted: 08/01/2021] [Indexed: 12/14/2022]
Abstract
We compared the regulation of the NaCl cotransporter (NCC) in adaptation to a low-K (LK) diet in male and female mice. We measured hydrochlorothiazide (HCTZ)-induced changes in urine volume (UV), glomerular filtration rate (GFR), absolute (ENa, EK), and fractional (FENa, FEK) excretion in male and female mice on control-K (CK, 1% KCl) and LK (0.1% KCl) diets for 7 days. With CK, NCC-dependent ENa and FENa were larger in females than males as observed previously. However, with LK, HCTZ-induced ENa and FENa increased in males but not in females, abolishing the sex differences in NCC function as observed in CK group. Despite large diuretic and natriuretic responses to HCTZ, EK was only slightly increased in response to the drug when animals were on LK. This suggests that the K-secretory apparatus in the distal nephron is strongly suppressed under these conditions. We also examined LK-induced changes in Na transport protein expression by Western blotting. Under CK conditions females expressed more NCC protein, as previously reported. LK doubled both total (tNCC) and phosphorylated NCC (pNCC) abundance in males but had more modest effects in females. The larger effect in males abolished the sex-dependence of NCC expression, consistent with the measurements of function by renal clearance. LK intake did not change NHE3, NHE2, or NKCC2 expression, but reduced the amount of the cleaved (presumably active) form of γENaC. LK reduced plasma K to lower levels in females than males. These results indicated that males had a stronger NCC-mediated adaptation to LK intake than females.
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Affiliation(s)
- Shuhua Xu
- grid.47100.320000000419368710Department of Cellular and Molecular Physiology, Yale School of Medicine University, 333 Cedar Street, P.O. Box 208026, New Haven, CT 06520-8026 USA
| | - Jing Li
- grid.47100.320000000419368710Department of Cellular and Molecular Physiology, Yale School of Medicine University, 333 Cedar Street, P.O. Box 208026, New Haven, CT 06520-8026 USA
| | - Lei Yang
- grid.5386.8000000041936877XDepartment of Physiology and Biophysics, Weill Medical College of Cornell University, New York, NY USA
| | - Claire J. Wang
- grid.47100.320000000419368710Department of Cellular and Molecular Physiology, Yale School of Medicine University, 333 Cedar Street, P.O. Box 208026, New Haven, CT 06520-8026 USA
| | - Tommy Liu
- grid.47100.320000000419368710Department of Cellular and Molecular Physiology, Yale School of Medicine University, 333 Cedar Street, P.O. Box 208026, New Haven, CT 06520-8026 USA
| | - Alan M. Weinstein
- grid.5386.8000000041936877XDepartment of Physiology and Biophysics, Weill Medical College of Cornell University, New York, NY USA
| | - Lawrence G. Palmer
- grid.5386.8000000041936877XDepartment of Physiology and Biophysics, Weill Medical College of Cornell University, New York, NY USA
| | - Tong Wang
- grid.47100.320000000419368710Department of Cellular and Molecular Physiology, Yale School of Medicine University, 333 Cedar Street, P.O. Box 208026, New Haven, CT 06520-8026 USA
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Abstract
PURPOSE OF REVIEW This review focuses on recent efforts in identifying with-no-lysine kinase 4 (WNK4) as a physiological intracellular chloride sensor and exploring regulators of intracellular chloride concentration ([Cl-]i) in the distal convoluted tubule (DCT). RECENT FINDINGS The discovery of WNK1's chloride-binding site provides the mechanistic details of the chloride-sensing regulation of WNK kinases. The subsequent in-vitro studies reveal that the chloride sensitivities of WNK kinases were variable. Because of its highest chloride sensitivity and dominant expression, WNK4 emerges as the leading candidate of the chloride sensor in DCT. The presentation of hypertension and increased sodium-chloride cotransporter (NCC) activity in chloride-insensitive WNK4 mice proved that WNK4 is inhibitable by physiological [Cl-]i in DCT. The chloride-mediated WNK4 regulation is responsible for hypokalemia-induced NCC activation but unnecessary for hyperkalemia-induced NCC deactivation. This chloride-sensing mechanism requires basolateral potassium and chloride channels or cotransporters, including Kir4.1/5.1, ClC-Kb, and possibly KCCs, to modulate [Cl-]i in response to the changes of plasma potassium. SUMMARY WNK4 is both a master NCC stimulator and an in-vivo chloride sensor in DCT. The understanding of chloride-mediated regulation of WNK4 explains the inverse relationship between dietary potassium intake and NCC activity.
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63
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Bovée DM, Cuevas CA, Zietse R, Danser AHJ, Mirabito Colafella KM, Hoorn EJ. Salt-sensitive hypertension in chronic kidney disease: distal tubular mechanisms. Am J Physiol Renal Physiol 2020; 319:F729-F745. [DOI: 10.1152/ajprenal.00407.2020] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Chronic kidney disease (CKD) causes salt-sensitive hypertension that is often resistant to treatment and contributes to the progression of kidney injury and cardiovascular disease. A better understanding of the mechanisms contributing to salt-sensitive hypertension in CKD is essential to improve these outcomes. This review critically explores these mechanisms by focusing on how CKD affects distal nephron Na+ reabsorption. CKD causes glomerulotubular imbalance with reduced proximal Na+ reabsorption and increased distal Na+ delivery and reabsorption. Aldosterone secretion further contributes to distal Na+ reabsorption in CKD and is not only mediated by renin and K+ but also by metabolic acidosis, endothelin-1, and vasopressin. CKD also activates the intrarenal renin-angiotensin system, generating intratubular angiotensin II to promote distal Na+ reabsorption. High dietary Na+ intake in CKD contributes to Na+ retention by aldosterone-independent activation of the mineralocorticoid receptor mediated through Rac1. High dietary Na+ also produces an inflammatory response mediated by T helper 17 cells and cytokines increasing distal Na+ transport. CKD is often accompanied by proteinuria, which contains plasmin capable of activating the epithelial Na+ channel. Thus, CKD causes both local and systemic changes that together promote distal nephron Na+ reabsorption and salt-sensitive hypertension. Future studies should address remaining knowledge gaps, including the relative contribution of each mechanism, the influence of sex, differences between stages and etiologies of CKD, and the clinical relevance of experimentally identified mechanisms. Several pathways offer opportunities for intervention, including with dietary Na+ reduction, distal diuretics, renin-angiotensin system inhibitors, mineralocorticoid receptor antagonists, and K+ or H+ binders.
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Affiliation(s)
- Dominique M. Bovée
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
- Division of Vascular Medicine, Department of Internal Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Catharina A. Cuevas
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Robert Zietse
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - A. H. Jan Danser
- Division of Vascular Medicine, Department of Internal Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Katrina M. Mirabito Colafella
- Cardiovascular Disease Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
- Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Ewout J. Hoorn
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
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Levanovich PE, Diaczok A, Rossi NF. Clinical and Molecular Perspectives of Monogenic Hypertension. Curr Hypertens Rev 2020; 16:91-107. [PMID: 30963979 PMCID: PMC7499356 DOI: 10.2174/1573402115666190409115330] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 04/02/2019] [Accepted: 04/04/2019] [Indexed: 12/12/2022]
Abstract
Advances in molecular research techniques have enabled a new frontier in discerning the mechanisms responsible for monogenic diseases. In this review, we discuss the current research on the molecular pathways governing blood pressure disorders with a Mendelian inheritance pattern, each presenting with a unique pathophysiology. Glucocorticoid Remediable Aldosteronism (GRA) and Apparent Mineralocorticoid Excess (AME) are caused by mutations in regulatory enzymes that induce increased production of mineralocorticoids or inhibit degradation of glucocorticoids, respectively. Geller syndrome is due to a point mutation in the hormone responsive element of the promotor for the mineralocorticoid receptor, rendering the receptor susceptible to activation by progesterone, leading to hypertension during pregnancy. Pseudohypoaldosteronism type II (PHA-II), also known as Gordon's syndrome or familial hyperkalemic hypertension, is a more variable disorder typically characterized by hypertension, high plasma potassium and metabolic acidosis. Mutations in a variety of intracellular enzymes that lead to enhanced sodium reabsorption have been identified. In contrast, hypertension in Liddle's syndrome, which results from mutations in the Epithelial sodium Channel (ENaC), is associated with low plasma potassium and metabolic alkalosis. In Liddle's syndrome, truncation of one the ENaC protein subunits removes a binding site necessary protein for ubiquitination and degradation, thereby promoting accumulation along the apical membrane and enhanced sodium reabsorption. The myriad effects due to mutation in phosphodiesterase 3A (PDE3A) lead to severe hypertension underlying sodium-independent autosomal dominant hypertension with brachydactyly. How mutations in PDE3A result in the phenotypic features of this disorder are discussed. Understanding the pathologies of these monogenic hypertensive disorders may provide insight into the causes of the more prevalent essential hypertension and new avenues to unravel the complexities of blood pressure regulation.
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Affiliation(s)
- Peter E Levanovich
- Department of Physiology, Wayne State University School of Medicine and the John D. Dingell VA Medical Center, Detroit, Michigan, MI 48201, United States
| | - Alexander Diaczok
- Department of Internal Medicine, Wayne State University School of Medicine and the John D. Dingell VA Medical Center, Detroit, Michigan, MI 48201, United States
| | - Noreen F Rossi
- Department of Physiology, Wayne State University School of Medicine and the John D. Dingell VA Medical Center, Detroit, Michigan, MI 48201, United States
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Murillo-de-Ozores AR, Chávez-Canales M, de Los Heros P, Gamba G, Castañeda-Bueno M. Physiological Processes Modulated by the Chloride-Sensitive WNK-SPAK/OSR1 Kinase Signaling Pathway and the Cation-Coupled Chloride Cotransporters. Front Physiol 2020; 11:585907. [PMID: 33192599 PMCID: PMC7606576 DOI: 10.3389/fphys.2020.585907] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 09/29/2020] [Indexed: 12/15/2022] Open
Abstract
The role of Cl– as an intracellular signaling ion has been increasingly recognized in recent years. One of the currently best described roles of Cl– in signaling is the modulation of the With-No-Lysine (K) (WNK) – STE20-Proline Alanine rich Kinase (SPAK)/Oxidative Stress Responsive Kinase 1 (OSR1) – Cation-Coupled Cl–Cotransporters (CCCs) cascade. Binding of a Cl– anion to the active site of WNK kinases directly modulates their activity, promoting their inhibition. WNK activation due to Cl– release from the binding site leads to phosphorylation and activation of SPAK/OSR1, which in turn phosphorylate the CCCs. Phosphorylation by WNKs-SPAK/OSR1 of the Na+-driven CCCs (mediating ions influx) promote their activation, whereas that of the K+-driven CCCs (mediating ions efflux) promote their inhibition. This results in net Cl– influx and feedback inhibition of WNK kinases. A wide variety of alterations to this pathway have been recognized as the cause of several human diseases, with manifestations in different systems. The understanding of WNK kinases as Cl– sensitive proteins has allowed us to better understand the mechanistic details of regulatory processes involved in diverse physiological phenomena that are reviewed here. These include cell volume regulation, potassium sensing and intracellular signaling in the renal distal convoluted tubule, and regulation of the neuronal response to the neurotransmitter GABA.
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Affiliation(s)
- Adrián Rafael Murillo-de-Ozores
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.,Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - María Chávez-Canales
- Unidad de Investigación UNAM-INC, Instituto Nacional de Cardiología Ignacio Chávez and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Paola de Los Heros
- Unidad de Investigación UNAM-INC, Research Division, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Gerardo Gamba
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.,Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - María Castañeda-Bueno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
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Verkhratsky A, Semyanov A, Zorec R. Physiology of Astroglial Excitability. FUNCTION (OXFORD, ENGLAND) 2020; 1:zqaa016. [PMID: 35330636 PMCID: PMC8788756 DOI: 10.1093/function/zqaa016] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 08/29/2020] [Accepted: 09/03/2020] [Indexed: 01/06/2023]
Abstract
Classic physiology divides all neural cells into excitable neurons and nonexcitable neuroglia. Neuroglial cells, chiefly responsible for homeostasis and defense of the nervous tissue, coordinate their complex homeostatic responses with neuronal activity. This coordination reflects a specific form of glial excitability mediated by complex changes in intracellular concentration of ions and second messengers organized in both space and time. Astrocytes are equipped with multiple molecular cascades, which are central for regulating homeostasis of neurotransmitters, ionostasis, synaptic connectivity, and metabolic support of the central nervous system. Astrocytes are further provisioned with multiple receptors for neurotransmitters and neurohormones, which upon activation trigger intracellular signals mediated by Ca2+, Na+, and cyclic AMP. Calcium signals have distinct organization and underlying mechanisms in different astrocytic compartments thus allowing complex spatiotemporal signaling. Signals mediated by fluctuations in cytosolic Na+ are instrumental for coordination of Na+ dependent astrocytic transporters with tissue state and homeostatic demands. Astroglial ionic excitability may also involve K+, H+, and Cl-. The cyclic AMP signalling system is, in comparison to ions, much slower in targeting astroglial effector mechanisms. This evidence review summarizes the concept of astroglial intracellular excitability.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK,Achucarro Center for Neuroscience, Ikerbasque, 48011 Bilbao, Spain,Address correspondence to A.V. (e-mail: )
| | - Alexey Semyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia,Faculty of Biology, Moscow State University, Moscow, Russia,Sechenov First Moscow State Medical University, Moscow, Russia
| | - Robert Zorec
- Celica Biomedical, Ljubljana 1000, Slovenia,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana 1000, Slovenia
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67
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Wei KY, Gritter M, Vogt L, de Borst MH, Rotmans JI, Hoorn EJ. Dietary potassium and the kidney: lifesaving physiology. Clin Kidney J 2020; 13:952-968. [PMID: 33391739 PMCID: PMC7769543 DOI: 10.1093/ckj/sfaa157] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Indexed: 02/07/2023] Open
Abstract
Potassium often has a negative connotation in Nephrology as patients with chronic kidney disease (CKD) are prone to develop hyperkalaemia. Approaches to the management of chronic hyperkalaemia include a low potassium diet or potassium binders. Yet, emerging data indicate that dietary potassium may be beneficial for patients with CKD. Epidemiological studies have shown that a higher urinary potassium excretion (as proxy for higher dietary potassium intake) is associated with lower blood pressure (BP) and lower cardiovascular risk, as well as better kidney outcomes. Considering that the composition of our current diet is characterized by a high sodium and low potassium content, increasing dietary potassium may be equally important as reducing sodium. Recent studies have revealed that dietary potassium modulates the activity of the thiazide-sensitive sodium-chloride cotransporter in the distal convoluted tubule (DCT). The DCT acts as a potassium sensor to control the delivery of sodium to the collecting duct, the potassium-secreting portion of the kidney. Physiologically, this allows immediate kaliuresis after a potassium load, and conservation of potassium during potassium deficiency. Clinically, it provides a novel explanation for the inverse relationship between dietary potassium and BP. Moreover, increasing dietary potassium intake can exert BP-independent effects on the kidney by relieving the deleterious effects of a low potassium diet (inflammation, oxidative stress and fibrosis). The aim of this comprehensive review is to link physiology with clinical medicine by proposing that the same mechanisms that allow us to excrete an acute potassium load also protect us from hypertension, cardiovascular disease and CKD.
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Affiliation(s)
- Kuang-Yu Wei
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands.,Department of Internal Medicine, Division of Nephrology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Martin Gritter
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Liffert Vogt
- Department of Internal Medicine, Division of Nephrology, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - Martin H de Borst
- Department of Internal Medicine, Division of Nephrology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Joris I Rotmans
- Department of Internal Medicine, Division of Nephrology, Leiden University Medical Center, Leiden, The Netherlands
| | - Ewout J Hoorn
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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68
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Abstract
PURPOSE OF REVIEW The main goal of this article is to discuss the role of the epithelial sodium channel (ENaC) in extracellular fluid and blood pressure regulation. RECENT FINDINGS Besides its role in sodium handling in the kidney, recent studies have found that ENaC expressed in other cells including immune cells can influence blood pressure via extra-renal mechanisms. Dendritic cells (DCs) are activated and contribute to salt-sensitive hypertension in an ENaC-dependent manner. We discuss recent studies on how ENaC is regulated in both the kidney and other sites including the vascular smooth muscles, endothelial cells, and immune cells. We also discuss how this extra-renal ENaC can play a role in salt-sensitive hypertension and its promise as a novel therapeutic target. The role of ENaC in blood pressure regulation in the kidney has been well studied. Recent human gene sequencing efforts have identified thousands of variants among the genes encoding ENaC, and research efforts to determine if these variants and their expression in extra-renal tissue play a role in hypertension will advance our understanding of the pathogenesis of ENaC-mediated cardiovascular disease and lead to novel therapeutic targets.
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Affiliation(s)
- Ashley L Pitzer
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, 2215 Garland Avenue, P415C Medical Research Building IV, Nashville, TN, 37232, USA
| | - Justin P Van Beusecum
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, 2215 Garland Avenue, P415C Medical Research Building IV, Nashville, TN, 37232, USA
| | - Thomas R Kleyman
- Departments of Medicine, Cell Biology, Pharmacology, and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Annet Kirabo
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, 2215 Garland Avenue, P415C Medical Research Building IV, Nashville, TN, 37232, USA. .,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.
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69
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Abstract
Hypochloraemia is a common electrolyte abnormality in patients with heart failure (HF). It has a strong association with adverse outcome regardless of HF phenotype and independent of other prognostic markers. How hypochloraemia develops in a patient with HF and how it might influence outcome are not clear, and in this review we explore the possible mechanisms. Patients with HF and hypochloraemia almost invariably take higher doses of loop diuretic than patients with normal chloride levels. However, renal chloride and bicarbonate homeostasis are closely linked, and the latter may be influenced by neurohormonal activation: it is likely that the etiology of hypochloraemia in patients with HF is multifactorial and due to more than just diuretic-induced urinary losses. There are multiple proposed mechanisms by which low chloride concentrations may lead to an adverse outcome in patients with HF: by increasing renin release; by a stimulatory effect on the with-no-lysine kinases which might increase renal sodium-chloride co-transporter activity; and by an adverse effect on myocardial conduction and contractility. None of these proposed mechanisms are proven in humans with HF. However, if true, it might suggest that hypochloraemia is a therapeutic target that might be amenable to treatment with acetazolamide or chloride supplementation.
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70
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Su XT, Klett NJ, Sharma A, Allen CN, Wang WH, Yang CL, Ellison DH. Distal convoluted tubule Cl - concentration is modulated via K + channels and transporters. Am J Physiol Renal Physiol 2020; 319:F534-F540. [PMID: 32715757 DOI: 10.1152/ajprenal.00284.2020] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cl--sensitive with-no-lysine kinase (WNK) plays a key role in regulating the thiazide-sensitive Na+-Cl- cotransporter (NCC) in the distal convoluted tubule (DCT). Cl- enters DCT cells through NCC and leaves the cell across the basolateral membrane via the Cl- channel ClC-K2 or K+-Cl- cotransporter (KCC). While KCC is electroneutral, Cl- exit via ClC-K2 is electrogenic. Therefore, an alteration in DCT basolateral K+ channel activity is expected to influence Cl- movement across the basolateral membrane. Although a role for intracellular Cl- in the regulation of WNK and NCC has been established, intracellular Cl- concentrations ([Cl-]i) have not been directly measured in the mammalian DCT. Therefore, to measure [Cl-]i in DCT cells, we generated a transgenic mouse model expressing an optogenetic kidney-specific Cl-Sensor and measured Cl- fluorescent imaging in the isolated DCT. Basal measurements indicated that the mean [Cl-]i was ~7 mM. Stimulation of Cl- exit with low-Cl- hypotonic solutions decreased [Cl-]i, whereas inhibition of KCC by DIOA or inhibition of ClC-K2 by NPPB increased [Cl-]i, suggesting roles for both KCC and ClC-K2 in the modulation of [Cl-]i . Blockade of basolateral K+ channels (Kir4.1/5.1) with barium significantly increased [Cl-]i. Finally, a decrease in extracellular K+ concentration transiently decreased [Cl-]i, whereas raising extracellular K+ transiently increased [Cl-]i, further suggesting a role for Kir4.1/5.1 in the regulation of [Cl-]i. We conclude that the alteration in ClC-K2, KCC, and Kir4.1/5.1 activity influences [Cl-]i in the DCT.
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Affiliation(s)
- Xiao-Tong Su
- Division of Nephrology and Hypertension, School of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Nathan J Klett
- Division of Nephrology and Hypertension, School of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Avika Sharma
- Division of Nephrology and Hypertension, School of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Charles N Allen
- Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland, Oregon.,Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Chao-Ling Yang
- Division of Nephrology and Hypertension, School of Medicine, Oregon Health and Science University, Portland, Oregon
| | - David H Ellison
- Division of Nephrology and Hypertension, School of Medicine, Oregon Health and Science University, Portland, Oregon.,Veterans Administration Portland Health Care System, Portland, Oregon
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Cornelius RJ, Sharma A, Su XT, Guo JJ, McMahon JA, Ellison DH, McMahon AP, McCormick JA. A novel distal convoluted tubule-specific Cre-recombinase driven by the NaCl cotransporter gene. Am J Physiol Renal Physiol 2020; 319:F423-F435. [PMID: 32657158 DOI: 10.1152/ajprenal.00101.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cre-lox technology has revolutionized research in renal physiology by allowing site-specific genetic recombination in individual nephron segments. The distal convoluted tubule (DCT), consisting of distinct early (DCT1) and late (DCT2) segments, plays a central role in Na+ and K+ homeostasis. The only established Cre line targeting the DCT is Pvalb-Cre, which is limited by noninducibility, activity along DCT1 only, and activity in neurons. Here, we report the characterization of the first Cre line specific to the entire DCT. CRISPR/Cas9 targeting was used to introduce a tamoxifen-inducible IRES-Cre-ERT2 cassette downstream of the coding region of the Slc12a3 gene encoding the NaCl cotransporter (NCC). The resulting Slc12a3-Cre-ERT2 mice were crossed with R26R-YFP reporter mice, which revealed minimal leakiness with 6.3% of NCC-positive cells expressing yellow fluorescent protein (YFP) in the absence of tamoxifen. After tamoxifen injection, YFP expression was observed in 91.2% of NCC-positive cells and only in NCC-positive cells, revealing high recombination efficiency and DCT specificity. Crossing to R26R-TdTomato mice revealed higher leakiness (64.5%), suggesting differential sensitivity of the floxed site. Western blot analysis revealed no differences in abundances of total NCC or the active phosphorylated form of NCC in Slc12a3-Cre-ERT2 mice of either sex compared with controls. Plasma K+ and Mg2+ concentrations and thiazide-sensitive Na+ and K+ excretion did not differ in Slc12a3-Cre-ERT2 mice compared with controls when sex matched. These data suggest genetic modification had no obvious effect on NCC function. Slc12a3-Cre-ERT2 mice are the first line generated demonstrating inducible Cre recombinase activity along the entire DCT and will be a useful tool to study DCT function.
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Affiliation(s)
- Ryan J Cornelius
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Avika Sharma
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Xiao-Tong Su
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Jin-Jin Guo
- Department of Stem Cell Biology and Regenerative Medicine, Broad California Institute of Regenerative Medicine Center, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Jill A McMahon
- Department of Stem Cell Biology and Regenerative Medicine, Broad California Institute of Regenerative Medicine Center, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon.,Veterans Affairs Portland Health Care System, Portland, Oregon
| | - Andrew P McMahon
- Department of Stem Cell Biology and Regenerative Medicine, Broad California Institute of Regenerative Medicine Center, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - James A McCormick
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
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Calcium-Sensing Receptor and Regulation of WNK Kinases in the Kidney. Cells 2020; 9:cells9071644. [PMID: 32659887 PMCID: PMC7407487 DOI: 10.3390/cells9071644] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 07/01/2020] [Accepted: 07/06/2020] [Indexed: 12/27/2022] Open
Abstract
The kidney is essential for systemic calcium homeostasis. Urinary calcium excretion can be viewed as an integrative renal response to endocrine and local stimuli. The extracellular calcium-sensing receptor (CaSR) elicits a number of adaptive reactions to increased plasma Ca2+ levels including the control of parathyroid hormone release and regulation of the renal calcium handling. Calcium reabsorption in the distal nephron of the kidney is functionally coupled to sodium transport. Apart from Ca2+ transport systems, CaSR signaling affects relevant distal Na+-(K+)-2Cl- cotransporters, NKCC2 and NCC. NKCC2 and NCC are activated by a kinase cascade comprising with-no-lysine [K] kinases (WNKs) and two homologous Ste20-related kinases, SPAK and OSR1. Gain-of-function mutations within the WNK-SPAK/OSR1-NKCC2/NCC pathway lead to renal salt retention and hypertension, whereas loss-of-function mutations have been associated with salt-losing tubulopathies such as Bartter or Gitelman syndromes. A Bartter-like syndrome has been also described in patients carrying gain-of-function mutations in the CaSR gene. Recent work suggested that CaSR signals via the WNK-SPAK/OSR1 cascade to modulate salt reabsorption along the distal nephron. The review presented here summarizes the latest progress in understanding of functional interactions between CaSR and WNKs and their potential impact on the renal salt handling and blood pressure.
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73
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Shoda W, Nomura N, Ando F, Tagashira H, Iwamoto T, Ohta A, Isobe K, Mori T, Susa K, Sohara E, Rai T, Uchida S. Sodium-calcium exchanger 1 is the key molecule for urinary potassium excretion against acute hyperkalemia. PLoS One 2020; 15:e0235360. [PMID: 32603346 PMCID: PMC7326190 DOI: 10.1371/journal.pone.0235360] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 06/13/2020] [Indexed: 02/07/2023] Open
Abstract
The sodium (Na+)-chloride cotransporter (NCC) expressed in the distal convoluted tubule (DCT) is a key molecule regulating urinary Na+ and potassium (K+) excretion. We previously reported that high-K+ load rapidly dephosphorylated NCC and promoted urinary K+ excretion in mouse kidneys. This effect was inhibited by calcineurin (CaN) and calmodulin inhibitors. However, the detailed mechanism through which high-K+ signal results in CaN activation remains unknown. We used Flp-In NCC HEK293 cells and mice to evaluate NCC phosphorylation. We analyzed intracellular Ca2+ concentration ([Ca2+]in) using live cell Ca2+ imaging in HEK293 cells. We confirmed that high-K+-induced NCC dephosphorylation was not observed without CaN using Flp-In NCC HEK29 cells. Extracellular Ca2+ reduction with a Ca2+ chelator inhibited high-K+-induced increase in [Ca2+]in and NCC dephosphorylation. We focused on Na+/Ca2+ exchanger (NCX) 1, a bidirectional regulator of cytosolic Ca2+ expressed in DCT. We identified that NCX1 suppression with a specific inhibitor (SEA0400) or siRNA knockdown inhibited K+-induced increase in [Ca2+]in and NCC dephosphorylation. In a mouse study, SEA0400 treatment inhibited K+-induced NCC dephosphorylation. SEA0400 reduced urinary K+ excretion and induced hyperkalemia. Here, we identified NCX1 as a key molecule in urinary K+ excretion promoted by CaN activation and NCC dephosphorylation in response to K+ load.
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Affiliation(s)
- Wakana Shoda
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Naohiro Nomura
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
- * E-mail:
| | - Fumiaki Ando
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Hideaki Tagashira
- Department of pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Takahiro Iwamoto
- Department of pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Akihito Ohta
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Kiyoshi Isobe
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Takayasu Mori
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Koichiro Susa
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Eisei Sohara
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Tatemitsu Rai
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Shinichi Uchida
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
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74
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Hamrahian SM, Fülöp T. Hyperkalemia and Hypertension Post Organ Transplantation - A Management Challenge. Am J Med Sci 2020; 361:106-110. [PMID: 32709394 DOI: 10.1016/j.amjms.2020.06.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 04/22/2020] [Accepted: 06/22/2020] [Indexed: 10/24/2022]
Abstract
Potassium is the most important intracellular cation and the kidneys play a pivotal role in potassium homeostasis. Potassium disorder is a common electrolyte abnormality and it increases the risk of death from any cause, particularly cardiovascular events. Hyperkalemia is a common electrolyte abnormality encountered post organ transplantation. The etiology is multifactorial, and includes drugs such as calcineurin inhibitors. In certain regards, the clinical picture of post-transplantation hyperkalemia and hypertension resembles that of Gordon syndrome or familial hyperkalemic hypertension, a disorder characterized by over activity of thiazide-sensitive sodium chloride cotransporter. Effective and safe management of chronic hyperkalemia can be challenging in this special patient population. Despite the significant short-term and long-term side effects, fludrocortisone (a potent synthetic oral mineralocorticoid receptor agonist) has emerged as the default drug of choice for treatment of refractory hyperkalemia in many organ transplant recipients. However, the long-term efficacy and safety of fludrocortisone for management of hyperkalemia in organ transplant recipients remains unknown. This review discusses potassium homeostasis, including the role of the kidneys, and focuses on calcineurin inhibitor-induced hyperkalemia and on the under-appreciated role of thiazide-type diuretic use in management of hyperkalemia and hypertension. We present an illustrative case of post-transplantation hyperkalemia and hypertension with relevant literature.
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Affiliation(s)
- Seyed Mehrdad Hamrahian
- Division of Nephrology, Department of Medicine, Thomas Jefferson University, Philadelphia, PA.
| | - Tibor Fülöp
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina; Medicine Service, Ralph H. Johnson VA Medical Center, Charleston, South Carolina
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75
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Pacheco-Alvarez D, Carrillo-Pérez DL, Mercado A, Leyva-Ríos K, Moreno E, Hernández-Mercado E, Castañeda-Bueno M, Vázquez N, Gamba G. WNK3 and WNK4 exhibit opposite sensitivity with respect to cell volume and intracellular chloride concentration. Am J Physiol Cell Physiol 2020; 319:C371-C380. [PMID: 32579473 DOI: 10.1152/ajpcell.00488.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cation-coupled chloride cotransporters (CCC) play a role in modulating intracellular chloride concentration ([Cl-]i) and cell volume. Cell shrinkage and cell swelling are accompanied by an increase or decrease in [Cl-]i, respectively. Cell shrinkage and a decrease in [Cl-]i increase the activity of NKCCs (Na-K-Cl cotransporters: NKCC1, NKCC2, and Na-Cl) and inhibit the activity of KCCs (K-Cl cotransporters: KCC1 to KCC4), wheras cell swelling and an increase in [Cl-]i activate KCCs and inhibit NKCCs; thus, it is unlikely that the same kinase is responsible for both effects. WNK1 and WNK4 are chloride-sensitive kinases that modulate the activity of CCC in response to changes in [Cl-]i. Here, we showed that WNK3, another member of the serine-threonine kinase WNK family with known effects on CCC, is not sensitive to [Cl-]i but can be regulated by changes in extracellular tonicity. In contrast, WNK4 is highly sensitive to [Cl-]i but is not regulated by changes in cell volume. The activity of WNK3 toward NaCl cotransporter is not affected by eliminating the chloride-binding site of WNK3, further confirming that the kinase is not sensitive to chloride. Chimeric WNK3/WNK4 proteins were produced, and analysis of the chimeras suggests that sequences within the WNK's carboxy-terminal end may modulate the chloride affinity. We propose that WNK3 is a cell volume-sensitive kinase that translates changes in cell volume into phosphorylation of CCC.
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Affiliation(s)
| | - Diego Luis Carrillo-Pérez
- Department of Medicine, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico.,Escuela de Medicina y Ciencias de la Salud, Tecnológico de Monterrey, Monterrey, Mexico
| | - Adriana Mercado
- Department of Nephrology, Instituto Nacional de Cardiología Ignacio Chávez, Tlalpan, Mexico City, Mexico
| | - Karla Leyva-Ríos
- Escuela de Medicina, Universidad Panamericana, Mexico City, Mexico
| | - Erika Moreno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico
| | | | - María Castañeda-Bueno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico
| | - Norma Vázquez
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Coyoacan, Mexico City, Mexico
| | - Gerardo Gamba
- Escuela de Medicina y Ciencias de la Salud, Tecnológico de Monterrey, Monterrey, Mexico.,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico.,Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Coyoacan, Mexico City, Mexico
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76
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Yasuda M, Inui TA, Hirano S, Asano S, Okazaki T, Inui T, Marunaka Y, Nakahari T. Intracellular Cl - Regulation of Ciliary Beating in Ciliated Human Nasal Epithelial Cells: Frequency and Distance of Ciliary Beating Observed by High-Speed Video Microscopy. Int J Mol Sci 2020; 21:ijms21114052. [PMID: 32517062 PMCID: PMC7312665 DOI: 10.3390/ijms21114052] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 05/28/2020] [Accepted: 06/03/2020] [Indexed: 12/12/2022] Open
Abstract
Small inhaled particles, which are entrapped by the mucous layer that is maintained by mucous secretion via mucin exocytosis and fluid secretion, are removed from the nasal cavity by beating cilia. The functional activities of beating cilia are assessed by their frequency and the amplitude. Nasal ciliary beating is controlled by intracellular ions (Ca2+, H+ and Cl-), and is enhanced by a decreased concentration of intracellular Cl- ([Cl-]i) in ciliated human nasal epithelial cells (cHNECs) in primary culture, which increases the ciliary beat amplitude. A novel method to measure both ciliary beat frequency (CBF) and ciliary beat distance (CBD, an index of ciliary beat amplitude) in cHNECs has been developed using high-speed video microscopy, which revealed that a decrease in [Cl-]i increased CBD, but not CBF, and an increase in [Cl-]i decreased both CBD and CBF. Thus, [Cl-]i inhibits ciliary beating in cHNECs, suggesting that axonemal structures controlling CBD and CBF may have Cl- sensors and be regulated by [Cl-]i. These observations indicate that the activation of Cl- secretion stimulates ciliary beating (increased CBD) mediated via a decrease in [Cl-]i in cHNECs. Thus, [Cl-]i is critical for controlling ciliary beating in cHNECs. This review introduces the concept of Cl- regulation of ciliary beating in cHNECs.
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Affiliation(s)
- Makoto Yasuda
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (T.-a.I.); (S.H.)
- Correspondence: (M.Y.); (T.N.); Tel.: +81-75-251-5603 (M.Y.); +81-77-561-3488 (ext. 7554) (T.N.)
| | - Taka-aki Inui
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (T.-a.I.); (S.H.)
| | - Shigeru Hirano
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; (T.-a.I.); (S.H.)
| | - Shinji Asano
- Research Unit for Epithelial Physiology, Research Organization of Science and Technology, BKC, Ritsumeikan University, Kusatsu 525-8577, Japan; (S.A.); (T.I.); (Y.M.)
- Department of Molecular Physiology, Faculty of Pharmaceutical Sciences, BKC, Ritsumeikan University, Kusatsu 525-8577, Japan;
| | - Tomonori Okazaki
- Department of Molecular Physiology, Faculty of Pharmaceutical Sciences, BKC, Ritsumeikan University, Kusatsu 525-8577, Japan;
| | - Toshio Inui
- Research Unit for Epithelial Physiology, Research Organization of Science and Technology, BKC, Ritsumeikan University, Kusatsu 525-8577, Japan; (S.A.); (T.I.); (Y.M.)
- Saisei Mirai Clinics, Moriguchi 570-0012, Japan
| | - Yoshinori Marunaka
- Research Unit for Epithelial Physiology, Research Organization of Science and Technology, BKC, Ritsumeikan University, Kusatsu 525-8577, Japan; (S.A.); (T.I.); (Y.M.)
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
- Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto 604-8472, Japan
| | - Takashi Nakahari
- Research Unit for Epithelial Physiology, Research Organization of Science and Technology, BKC, Ritsumeikan University, Kusatsu 525-8577, Japan; (S.A.); (T.I.); (Y.M.)
- Correspondence: (M.Y.); (T.N.); Tel.: +81-75-251-5603 (M.Y.); +81-77-561-3488 (ext. 7554) (T.N.)
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77
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Boyd-Shiwarski CR, Weaver CJ, Beacham RT, Shiwarski DJ, Connolly KA, Nkashama LJ, Mutchler SM, Griffiths SE, Knoell SA, Sebastiani RS, Ray EC, Marciszyn AL, Subramanya AR. Effects of extreme potassium stress on blood pressure and renal tubular sodium transport. Am J Physiol Renal Physiol 2020; 318:F1341-F1356. [PMID: 32281415 PMCID: PMC7311711 DOI: 10.1152/ajprenal.00527.2019] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We characterized mouse blood pressure and ion transport in the setting of commonly used rodent diets that drive K+ intake to the extremes of deficiency and excess. Male 129S2/Sv mice were fed either K+-deficient, control, high-K+ basic, or high-KCl diets for 10 days. Mice maintained on a K+-deficient diet exhibited no change in blood pressure, whereas K+-loaded mice developed an ~10-mmHg blood pressure increase. Following challenge with NaCl, K+-deficient mice developed a salt-sensitive 8 mmHg increase in blood pressure, whereas blood pressure was unchanged in mice fed high-K+ diets. Notably, 10 days of K+ depletion induced diabetes insipidus and upregulation of phosphorylated NaCl cotransporter, proximal Na+ transporters, and pendrin, likely contributing to the K+-deficient NaCl sensitivity. While the anionic content with high-K+ diets had distinct effects on transporter expression along the nephron, both K+ basic and KCl diets had a similar increase in blood pressure. The blood pressure elevation on high-K+ diets correlated with increased Na+-K+-2Cl- cotransporter and γ-epithelial Na+ channel expression and increased urinary response to furosemide and amiloride. We conclude that the dietary K+ maneuvers used here did not recapitulate the inverse effects of K+ on blood pressure observed in human epidemiological studies. This may be due to the extreme degree of K+ stress, the low-Na+-to-K+ ratio, the duration of treatment, and the development of other coinciding events, such as diabetes insipidus. These factors must be taken into consideration when studying the physiological effects of dietary K+ loading and depletion.
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Affiliation(s)
- Cary R. Boyd-Shiwarski
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Claire J. Weaver
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Rebecca T. Beacham
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Daniel J. Shiwarski
- 2Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Kelly A. Connolly
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Lubika J. Nkashama
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Stephanie M. Mutchler
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Shawn E. Griffiths
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Sophia A. Knoell
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Romano S. Sebastiani
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Evan C. Ray
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Allison L. Marciszyn
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Arohan R. Subramanya
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania,3Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania,4Veterans Administration, Pittsburgh Healthcare System, Pittsburgh Pennsylvania
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78
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Akella R, Drozdz MA, Humphreys JM, Jiou J, Durbacz MZ, Mohammed ZJ, He H, Liwocha J, Sekulski K, Goldsmith EJ. A Phosphorylated Intermediate in the Activation of WNK Kinases. Biochemistry 2020; 59:1747-1755. [PMID: 32314908 PMCID: PMC7914002 DOI: 10.1021/acs.biochem.0c00146] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
WNK kinases autoactivate by autophosphorylation. Crystallography of the kinase domain of WNK1 phosphorylated on the primary activating site (pWNK1) in the presence of AMP-PNP reveals a well-ordered but inactive configuration. This new pWNK1 structure features specific and unique interactions of the phosphoserine, less hydration, and smaller cavities compared with those of unphosphorylated WNK1 (uWNK1). Because WNKs are activated by osmotic stress in cells, we addressed whether the structure was influenced directly by osmotic pressure. pWNK1 crystals formed in PEG3350 were soaked in the osmolyte sucrose. Suc-WNK1 crystals maintained X-ray diffraction, but the lattice constants and pWNK1 structure changed. Differences were found in the activation loop and helix C, common switch loci in kinase activation. On the basis of these structural changes, we tested for effects on in vitro activity of two WNKs, pWNK1 and pWNK3. The osmolyte PEG400 enhanced ATPase activity. Our data suggest multistage activation of WNKs.
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Affiliation(s)
- Radha Akella
- Department of Biophysics, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8816, USA
| | - Mateusz A. Drozdz
- Department of Biophysics, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8816, USA
| | - John M. Humphreys
- Department of Biophysics, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8816, USA
| | - Jenny Jiou
- Department of Biophysics, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8816, USA
| | - Mateusz Z. Durbacz
- Faculty of Agronomy and Bioengineering, University of Life Sciences, Wojska Polskiego 28, 60-624 Poznan, Poland
| | - Zuhair J. Mohammed
- Biomedical Engineering, University of Texas at Dallas, Richardson, TX 75080
| | - Haixia He
- Department of Biophysics, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8816, USA
| | - Joanna Liwocha
- Department of Molecular Machines and Signaling, Max Planck Institute for Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
| | - Kamil Sekulski
- Department of Biophysics, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8816, USA
| | - Elizabeth J. Goldsmith
- Department of Biophysics, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8816, USA
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79
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Abstract
PURPOSE OF REVIEW Studies of the genetic model organism, Drosophila melanogaster, have unraveled molecular pathways relevant to human physiology and disease. The Malpighian tubule, the Drosophila renal epithelium, is described here, including tools available to study transport; conserved transporters, channels, and the signaling pathways regulating them; and fly models of kidney stone disease. RECENT FINDINGS Tools to measure Malpighian tubule transport continue to advance, including use of a transgenic sensor to quantify intracellular pH and proton fluxes. A recent study generated an RNA-sequencing-based atlas of tissue-specific gene expression, with resulting insights into Malpighian tubule gene expression of transporters and channels. Advances have been made in understanding the molecular physiology of the With No Lysine kinase-Ste20-related proline/alanine rich kinase/oxidative stress response kinase cascade that regulates epithelial ion transport in flies and mammals. New studies in Drosophila kidney stone models have characterized zinc transporters and used Malpighian tubules to study the efficacy of a plant metabolite in decreasing stone burden. SUMMARY Study of the Drosophila Malpighian tubule affords opportunities to better characterize the molecular physiology of epithelial transport mechanisms relevant to mammalian renal physiology.
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80
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Wu P, Su XT, Gao ZX, Zhang DD, Duan XP, Xiao Y, Staub O, Wang WH, Lin DH. Renal Tubule Nedd4-2 Deficiency Stimulates Kir4.1/Kir5.1 and Thiazide-Sensitive NaCl Cotransporter in Distal Convoluted Tubule. J Am Soc Nephrol 2020; 31:1226-1242. [PMID: 32295826 DOI: 10.1681/asn.2019090923] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 03/07/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The potassium channel Kir4.1 forms the Kir4.1/Kir5.1 heterotetramer in the basolateral membrane of the distal convoluted tubule (DCT) and plays an important role in the regulation of the thiazide-sensitive NaCl cotransporter (NCC). Kidney-specific deletion of the ubiquitin ligase Nedd4-2 increases expression of NCC, and coexpression of Nedd4-2 inhibits Kir4.1/Kir5.1 in vitro. Whether Nedd4-2 regulates NCC expression in part by regulating Kir4.1/Kir5.1 channel activity in the DCT is unknown. METHODS We used electrophysiology studies, immunoblotting, immunostaining, and renal clearance to examine Kir4.1/Kir5.1 activity in the DCT and NCC expression/activity in wild-type mice and mice with kidney-specific knockout of Nedd4-2, Kir4.1, or both. RESULTS Deletion of Nedd4-2 increased the activity/expression of Kir4.1 in the DCT and also, hyperpolarized the DCT membrane. Expression of phosphorylated NCC/total NCC and thiazide-induced natriuresis were significantly increased in the Nedd4-2 knockout mice, but these mice were normokalemic. Double-knockout mice lacking both Kir4.1/Kir5.1 and Nedd4-2 in the kidney exhibited increased expression of the epithelial sodium channel α-subunit, largely abolished basolateral potassium ion conductance (to a degree similar to that of kidney-specific Kir4.1 knockout mice), and depolarization of the DCT membrane. Compared with wild-type mice, the double-knockout mice displayed inhibited expression of phosphorylated NCC and total NCC and had significantly blunted thiazide-induced natriuresis as well as renal potassium wasting and hypokalemia. However, NCC expression/activity was higher in the double-knockout mice than in Kir4.1 knockout mice. CONCLUSIONS Nedd4-2 regulates Kir4.1/Kir5.1 expression/activity in the DCT and modulates NCC expression by Kir4.1-dependent and Kir4.1-independent mechanisms. Basolateral Kir4.1/Kir5.1 activity in the DCT partially accounts for the stimulation of NCC activity/expression induced by deletion of Nedd4-2.
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Affiliation(s)
- Peng Wu
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Xiao-Tong Su
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Zhong-Xiuzi Gao
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dan-Dan Zhang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Xin-Peng Duan
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Yu Xiao
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Olivier Staub
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York
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81
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Furusho T, Uchida S, Sohara E. The WNK signaling pathway and salt-sensitive hypertension. Hypertens Res 2020; 43:733-743. [PMID: 32286498 DOI: 10.1038/s41440-020-0437-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 03/11/2020] [Accepted: 03/11/2020] [Indexed: 12/19/2022]
Abstract
The distal nephron of the kidney has a central role in sodium and fluid homeostasis, and disruption of this homeostasis due to mutations of with-no-lysine kinase 1 (WNK1), WNK4, Kelch-like 3 (KLHL3), or Cullin 3 (CUL3) causes pseudohypoaldosteronism type II (PHAII), an inherited hypertensive disease. WNK1 and WNK4 activate the NaCl cotransporter (NCC) at the distal convoluted tubule through oxidative stress-responsive gene 1 (OSR1)/Ste20-related proline-alanine-rich kinase (SPAK), constituting the WNK-OSR1/SPAK-NCC phosphorylation cascade. The level of WNK protein is regulated through degradation by the CUL3-KLHL3 E3 ligase complex. In the normal state, the activity of WNK signaling in the kidney is physiologically regulated by sodium intake to maintain sodium homeostasis in the body. In patients with PHAII, however, because of the defective degradation of WNK kinases, NCC is constitutively active and not properly suppressed by a high salt diet, leading to abnormally increased salt reabsorption and salt-sensitive hypertension. Importantly, recent studies have demonstrated that potassium intake, insulin, and TNFα are also physiological regulators of WNK signaling, suggesting that they contribute to the salt-sensitive hypertension associated with a low potassium diet, metabolic syndrome, and chronic kidney disease, respectively. Moreover, emerging evidence suggests that WNK signaling also has some unique roles in metabolic, cardiovascular, and immunological organs. Here, we review the recent literature and discuss the molecular mechanisms of the WNK signaling pathway and its potential as a therapeutic target.
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Affiliation(s)
- Taisuke Furusho
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Shinichi Uchida
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Eisei Sohara
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
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82
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Intracellular chloride: a regulator of transepithelial transport in the distal nephron. Curr Opin Nephrol Hypertens 2020; 28:360-367. [PMID: 30865168 DOI: 10.1097/mnh.0000000000000502] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW This review focuses on the role of intracellular chloride in regulating transepithelial ion transport in the distal convoluted tubule (DCT) in response to perturbations in plasma potassium homeostasis. RECENT FINDINGS Low dietary potassium increases the phosphorylation and activity of the sodium chloride cotransporter (NCC) in the DCT, and vice versa, affecting sodium-dependent potassium secretion in the downstream aldosterone-sensitive distal nephron. In cells, NCC phosphorylation is increased by lowering of intracellular chloride, via activation of the chloride-sensitive with no lysine (WNK)-SPAK/OSR1 (Ste20-related proline/alanine-rich kinase/oxidative stress response) kinase cascade. In-vivo studies have demonstrated pathway activation in the kidney in response to low dietary potassium. A possible mechanism is lowering of DCT intracellular chloride in response to low potassium because of parallel basolateral potassium and chloride channels. Recent studies support a role for these channels in the response of NCC to varying potassium. Studies examining chloride-insensitive WNK mutants, in the Drosophila renal tubule and in the mouse, lend further support to a role for chloride in regulating WNK activity and transepithelial ion transport. Caveats, alternatives, and future directions are also discussed. SUMMARY Chloride sensing by WNK kinase provides a mechanism to allow coupling of extracellular potassium with NCC phosphorylation and activity to maintain potassium homeostasis.
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83
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Felker GM, Ellison DH, Mullens W, Cox ZL, Testani JM. Diuretic Therapy for Patients With Heart Failure. J Am Coll Cardiol 2020; 75:1178-1195. [DOI: 10.1016/j.jacc.2019.12.059] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 11/15/2019] [Accepted: 12/02/2019] [Indexed: 12/12/2022]
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84
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Abstract
Eating more potassium may reduce blood pressure and the occurrence of other cardiovascular diseases by actions on various systems, including the vasculature, the sympathetic nervous system, systemic metabolism, and body fluid volume. Among these, the kidney plays a major role in the potassium-rich diet-mediated blood pressure reduction. PURPOSE OF REVIEW: To provide an overview of recent discoveries about the mechanisms by which a potassium-rich diet leads to natriuresis. RECENT FINDINGS: Although the distal convoluted tubule (DCT) is a short part of the nephron that reabsorbs salt, via the sodium-chloride cotransporter (NCC), it is highly sensitive to changes in plasma potassium concentration. Activation or inhibition of NCC raises or lowers blood pressure. Recent work suggests that extracellular potassium concentration is sensed by the DCT via intracellular chloride concentration which regulates WNK kinases in the DCT. High-potassium diet targets NCC in the DCT, resulting in natriuresis and fluid volume reduction, which are protective from hypertension and other cardiovascular problems.
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Affiliation(s)
- Xiao-Tong Su
- School of Medicine, Oregon Health and Science University, Portland, OR USA
| | - Chao-Ling Yang
- School of Medicine, Oregon Health and Science University, Portland, OR USA
| | - David H. Ellison
- School of Medicine, Oregon Health and Science University, Portland, OR USA ,Oregon Clinical & Translational Research Institute, SN4N, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239 USA ,Veterans Administration Portland Health Care System, Portland, OR USA
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85
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Hoorn EJ, Gritter M, Cuevas CA, Fenton RA. Regulation of the Renal NaCl Cotransporter and Its Role in Potassium Homeostasis. Physiol Rev 2020; 100:321-356. [DOI: 10.1152/physrev.00044.2018] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Daily dietary potassium (K+) intake may be as large as the extracellular K+ pool. To avoid acute hyperkalemia, rapid removal of K+ from the extracellular space is essential. This is achieved by translocating K+ into cells and increasing urinary K+ excretion. Emerging data now indicate that the renal thiazide-sensitive NaCl cotransporter (NCC) is critically involved in this homeostatic kaliuretic response. This suggests that the early distal convoluted tubule (DCT) is a K+ sensor that can modify sodium (Na+) delivery to downstream segments to promote or limit K+ secretion. K+ sensing is mediated by the basolateral K+ channels Kir4.1/5.1, a capacity that the DCT likely shares with other nephron segments. Thus, next to K+-induced aldosterone secretion, K+ sensing by renal epithelial cells represents a second feedback mechanism to control K+ balance. NCC’s role in K+ homeostasis has both physiological and pathophysiological implications. During hypovolemia, NCC activation by the renin-angiotensin system stimulates Na+ reabsorption while preventing K+ secretion. Conversely, NCC inactivation by high dietary K+ intake maximizes kaliuresis and limits Na+ retention, despite high aldosterone levels. NCC activation by a low-K+ diet contributes to salt-sensitive hypertension. K+-induced natriuresis through NCC offers a novel explanation for the antihypertensive effects of a high-K+ diet. A possible role for K+ in chronic kidney disease is also emerging, as epidemiological data reveal associations between higher urinary K+ excretion and improved renal outcomes. This comprehensive review will embed these novel insights on NCC regulation into existing concepts of K+ homeostasis in health and disease.
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Affiliation(s)
- Ewout J. Hoorn
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands; and Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Martin Gritter
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands; and Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Catherina A. Cuevas
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands; and Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Robert A. Fenton
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands; and Department of Biomedicine, Aarhus University, Aarhus, Denmark
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86
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Dizin E, Olivier V, Maire C, Komarynets O, Sassi A, Roth I, Loffing J, de Seigneux S, Maillard M, Rutkowski JM, Edwards A, Feraille E. Time-course of sodium transport along the nephron in nephrotic syndrome: The role of potassium. FASEB J 2019; 34:2408-2424. [PMID: 31908015 DOI: 10.1096/fj.201901345r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 11/21/2019] [Accepted: 11/30/2019] [Indexed: 11/11/2022]
Abstract
The mechanism of sodium retention and its location in kidney tubules may vary with time in nephrotic syndrome (NS). We studied the mechanisms of sodium retention in transgenic POD-ATTAC mice, which display an inducible podocyte-specific apoptosis. At day 2 after the induction of NS, the increased abundance of NHE3 and phosphorylated NCC in nephrotic mice compared with controls suggest that early sodium retention occurs mainly in the proximal and distal tubules. At day 3, the abundance of NHE3 normalized, phosphorylated NCC levels decreased, and cleavage and apical localization of γ-ENaC increased in nephrotic mice. These findings indicate that sodium retention shifted from the proximal and distal tubules to the collecting system. Increased cleavage and apical localization of γ-ENaC persisted at day 5 in nephrotic mice when hypovolemia resolved and steady-state was reached. Sodium retention and γ-ENaC cleavage were independent of the increased plasma levels of aldosterone. Nephrotic mice displayed decreased glomerular filtration rate and urinary potassium excretion associated with hyperkaliemia at day 3. Feeding nephrotic mice with a low potassium diet prevented hyperkaliemia, γ-ENaC cleavage, and led to persistent increased phosphorylation of NCC. These results suggest that potassium homeostasis is a major determinant of the tubular site of sodium retention in nephrotic mice.
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Affiliation(s)
- Eva Dizin
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland.,National Centre of Competence in Research "Kidney.ch", Zürich, Switzerland
| | - Valérie Olivier
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland.,National Centre of Competence in Research "Kidney.ch", Zürich, Switzerland
| | - Charline Maire
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland.,National Centre of Competence in Research "Kidney.ch", Zürich, Switzerland
| | - Olga Komarynets
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland
| | - Ali Sassi
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland
| | - Isabelle Roth
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland.,National Centre of Competence in Research "Kidney.ch", Zürich, Switzerland
| | - Johannes Loffing
- National Centre of Competence in Research "Kidney.ch", Zürich, Switzerland.,Institute of Anatomy, University of Zürich, Zürich, Switzerland
| | - Sophie de Seigneux
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland.,National Centre of Competence in Research "Kidney.ch", Zürich, Switzerland
| | - Marc Maillard
- Service of Nephrology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Joseph M Rutkowski
- Department of Medical Physiology, Texas A&M University Health Science Center, Bryan, TX, USA
| | - Aurélie Edwards
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Eric Feraille
- Department of Cellular Physiology and Metabolism, University of Geneva, CMU, Geneva, Switzerland.,National Centre of Competence in Research "Kidney.ch", Zürich, Switzerland
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87
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Gu L, Wang J, Zhang DD, Meng X, Zhang Y, Zhang J, Zhang H, Guo X, Lin DH, Wang WH, Gu RM. Inhibition of AT2R and Bradykinin Type II Receptor (BK2R) Compromises High K + Intake-Induced Renal K + Excretion. Hypertension 2019; 75:439-448. [PMID: 31865783 DOI: 10.1161/hypertensionaha.119.13852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The inhibition of Type II angiotensin II receptor (AT2R) or BK2R (bradykinin type II receptor) stimulates basolateral Kir4.1/Kir5.1 in the distal convoluted tubule (DCT) and activates thiazide-sensitive NCC (Na-Cl cotransporter). The aim of the present study is to examine the role of AT2R and BK2R in mediating the effect of HK (high dietary K+) intake on the basolateral K+ channels, NCC, and renal K+ excretion. Feeding mice (male and female) with HK diet for overnight significantly decreased the basolateral K+ conductance, depolarized the DCT membrane, diminished the expression of pNCC (phosphorylated NCC) and tNCC (total NCC), and decreased thiazide-sensitive natriuresis. Overnight HK intake also increased the expression of cleaved ENaC-α and -γ subunits but had no effect on NKCC2 expression. Pretreatment of the mice (male and female) with PD123319 and HOE140 stimulated the expression of tNCC and pNCC, augmented hydrochlorothiazide-induced natriuresis, and increased the negativity of the DCT membrane. The deletion of Kir4.1 not only decreased the NCC activity but also abolished the stimulatory effect of PD123319 and HOE140 perfusion on NCC activity. Moreover, the effect of overnight HK loading on Kir4.1/Kir5.1 in the DCT and NCC expression/activity was compromised in the mice treated with AT2R/BK2R antagonists. Renal clearance study showed that inhibition of AT2R and BK2R impairs renal K+ excretion in response to overnight HK loading, and the mice pretreated with PD123319 and HOE140 were hyperkalemic during HK intake. We conclude that synergistic activation of AT2R and BK2R is required for the effect of overnight HK diet on Kir4.1/Kir5.1 in the DCT and NCC activity.
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Affiliation(s)
- Li Gu
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
| | - JunLin Wang
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
| | - Dan-Dan Zhang
- Department of Pharmacology, New York Medical College, Valhalla (D.-D. Z., D.-H.L, W.-H.W.)
| | - XinXin Meng
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
| | - YunHong Zhang
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
| | - JiaWen Zhang
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
| | - Hao Zhang
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
| | - XiWen Guo
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla (D.-D. Z., D.-H.L, W.-H.W.)
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla (D.-D. Z., D.-H.L, W.-H.W.)
| | - Rui-Min Gu
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
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88
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Lee HW, Harris AN, Romero MF, Welling PA, Wingo CS, Verlander JW, Weiner ID. NBCe1-A is required for the renal ammonia and K + response to hypokalemia. Am J Physiol Renal Physiol 2019; 318:F402-F421. [PMID: 31841393 DOI: 10.1152/ajprenal.00481.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Hypokalemia increases ammonia excretion and decreases K+ excretion. The present study examined the role of the proximal tubule protein NBCe1-A in these responses. We studied mice with Na+-bicarbonate cotransporter electrogenic, isoform 1, splice variant A (NBCe1-A) deletion [knockout (KO) mice] and their wild-type (WT) littermates were provided either K+ control or K+-free diet. We also used tissue sections to determine the effect of extracellular ammonia on NaCl cotransporter (NCC) phosphorylation. The K+-free diet significantly increased proximal tubule NBCe1-A and ammonia excretion in WT mice, and NBCe1-A deletion blunted the ammonia excretion response. NBCe1-A deletion inhibited the ammoniagenic/ammonia recycling enzyme response in the cortical proximal tubule (PT), where NBCe1-A is present in WT mice. In the outer medulla, where NBCe1-A is not present, the PT ammonia metabolism response was accentuated by NBCe1-A deletion. KO mice developed more severe hypokalemia and had greater urinary K+ excretion during the K+-free diet than did WT mice. This was associated with blunting of the hypokalemia-induced change in NCC phosphorylation. NBCe1-A KO mice have systemic metabolic acidosis, but experimentally induced metabolic acidosis did not alter NCC phosphorylation. Although KO mice have impaired ammonia metabolism, experiments in tissue sections showed that lack of ammonia does impair NCC phosphorylation. Finally, urinary aldosterone was greater in KO mice than in WT mice, but neither expression of epithelial Na+ channel α-, β-, and γ-subunits nor of H+-K+-ATPase α1- or α2-subunits correlated with changes in urinary K+. We conclude that NBCe1-A is critical for the effect of diet-induced hypokalemia to increase cortical proximal tubule ammonia generation and for the expected decrease in urinary K+ excretion.
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Affiliation(s)
- Hyun-Wook Lee
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Autumn N Harris
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Michael F Romero
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Paul A Welling
- Nephrology Division, Departments of Medicine and Physiology, Johns Hopkins Medical School, Baltimore, Maryland
| | - Charles S Wingo
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida.,Nephrology and Hypertension Section, Gainesville Veterans Affairs Medical Center, Gainesville, Florida
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - I David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida.,Nephrology and Hypertension Section, Gainesville Veterans Affairs Medical Center, Gainesville, Florida
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89
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Mutig K, Bachmann S. Hyperkalemia and blood pressure regulation. Nephrol Dial Transplant 2019; 34:iii26-iii35. [PMID: 31800077 DOI: 10.1093/ndt/gfz218] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Indexed: 11/12/2022] Open
Abstract
Hypertension is common in the general population. Management of hypertensive patients at risk of hyperkalemia is challenging due to potential life-threatening complications such as cardiac arrest. Chronic hyperkalemia is often associated with impaired renal ability to excrete excessive potassium ions (K+). This may refer to chronic kidney disease or certain pharmacological interventions, including broadly used renin-angiotensin-aldosterone system and calcineurin inhibitors. Understanding the intrinsic mechanisms permitting kidney adaptations to hyperkalemia is critical for choosing therapeutic strategies. Valuable insights were obtained from the analysis of familial hyperkalemic hypertension (FHHt) syndrome, which became a classic model for coincidence of high blood pressure and hyperkalemia. FHHt can be caused by mutations in several genes, all of them resulting in excessive activity of with-no-lysine kinases (WNKs) in the distal nephron of the kidney. WNKs have been increasingly recognized as key signalling enzymes in the regulation of renal sodium ions (Na+) and K+ handling, enabling adaptive responses to systemic shifts of potassium homoeostasis consequent to variations in dietary potassium intake or disease. The WNK signalling pathway recruits a complex protein network mediating catalytic and non-catalytic effects of distinct WNK isoforms on relevant Na+- or K+-transporting proteins. In this review article, we summarize recent progress in understanding WNK signalling. An update of available models for renal adaptation to hyperkalemic conditions is presented. Consequences for blood pressure regulation are discussed. Pharmacological targeting of WNKs or their substrates offers promising options to manage hypertension while preventing hyperkalemia.
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Affiliation(s)
- Kerim Mutig
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Department of Pharmacology, I.M. Sechenov First Moscow State Medical University of the Ministry of Healthcare of the Russian Federation (Sechenovskiy University), Moscow, Russia
| | - Sebastian Bachmann
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
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90
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Gritter M, Rotmans JI, Hoorn EJ. Role of Dietary K + in Natriuresis, Blood Pressure Reduction, Cardiovascular Protection, and Renoprotection. Hypertension 2019; 73:15-23. [PMID: 30571564 DOI: 10.1161/hypertensionaha.118.11209] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Martin Gritter
- From the Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands (M.G., E.J.H.)
| | - Joris I Rotmans
- Department of Internal Medicine-Nephrology, Leiden University Medical Center, the Netherlands (J.I.R.)
| | - Ewout J Hoorn
- From the Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands (M.G., E.J.H.)
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91
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Abstract
Epithelial Na+ channels (ENaCs) are members of a family of cation channels that function as sensors of the extracellular environment. ENaCs are activated by specific proteases in the biosynthetic pathway and at the cell surface and remove embedded inhibitory tracts, which allows channels to transition to higher open-probability states. Resolved structures of ENaC and an acid-sensing ion channel revealed highly organized extracellular regions. Within the periphery of ENaC subunits are unique domains formed by antiparallel β-strands containing the inhibitory tracts and protease cleavage sites. ENaCs are inhibited by Na+ binding to specific extracellular site(s), which promotes channel transition to a lower open-probability state. Specific inositol phospholipids and channel modification by Cys-palmitoylation enhance channel open probability. How these regulatory factors interact in a concerted manner to influence channel open probability is an important question that has not been resolved. These various factors are reviewed, and the impact of specific factors on human disorders is discussed.
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Affiliation(s)
- Thomas R Kleyman
- Renal-Electrolyte Division, Department of Medicine, and Departments of Cell Biology and of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Douglas C Eaton
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, Georgia
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92
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Abstract
Cl- is the major extracellular (Cl-out) and intracellular (Cl-in) anion whose concentration is actively regulated by multiple transporters. These transporters generate Cl- gradients across the plasma membrane and between the cytoplasm and intracellular organelles. [Cl-]in changes rapidly in response to cell stimulation and influences many physiological functions, as well as cellular and systemic homeostasis. However, less appreciated is the signaling function of Cl-. Cl- interacts with multiple proteins to directly modify their activity. This review highlights the signaling function of Cl- and argues that Cl- is a bona fide signaling ion, a function deserving extensive exploration.
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Affiliation(s)
- Benjamin P Lüscher
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland
| | - Laura Vachel
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland
| | - Ehud Ohana
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Shmuel Muallem
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland
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93
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Murthy M, O’Shaughnessy KM. Modified HEK cells simulate DCT cells in their sensitivity and response to changes in extracellular K. Physiol Rep 2019; 7:e14280. [PMID: 31762176 PMCID: PMC6875656 DOI: 10.14814/phy2.14280] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
A potassium (K+ ) rich diet is known to have an antihypertensive effect that has been embodied by the NHLBI in the DASH diet. However, the molecular basis for this blood pressure-lowering effect has been unclear, until a recent study proposed a model in which the DCT cells of the kidney regulate their salt transport in response to variations in intracellular chloride ([Cl- ]i ), which are directly regulated by serum K+ . With the knowledge that WNK proteins are Cl- sensors, and are a part of the WNK/SPAK/NCC signaling cascade which regulates the NCC, the main salt transporter in the distal nephron, we examined the effect of serum K+ on the ([Cl- ]i ) and, in turn its effect on the WNK4 signaling pathway in a "modified HEK 293T" cell line. Using a fluorescence-based approach in this cell line, we have shown that the membrane potential of the cell membrane is sensitive to the small changes in external KCl within the physiological range (2-5 mM), thus functioning as a K+ electrode. When the extracellular K+ was progressively increased (2-5 mM), the membrane depolarization lead to a subsequent increase in [Cl- ]i measured by fluorescence quenching of an intracellular chloride sensor. Increase in extracellular [K] resulted in a decrease in the phosphorylation of the WNK4 protein and its downstream targets, SPAK and NCC. This confirms that small changes in serum K can affect WNK4/SPAK/NCC signaling and transcellular Na+ flux through the DCT and provide a possible mechanism by which a K-rich DASH diet could reduce blood pressure.
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Affiliation(s)
- Meena Murthy
- Division of Experimental Medicine and ImmunotherapeuticsDepartment of MedicineUniversity of CambridgeCambridgeUK
| | - Kevin M. O’Shaughnessy
- Division of Experimental Medicine and ImmunotherapeuticsDepartment of MedicineUniversity of CambridgeCambridgeUK
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94
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Ferdaus MZ, Mukherjee A, Nelson JW, Blatt PJ, Miller LN, Terker AS, Staub O, Lin DH, McCormick JA. Mg 2+ restriction downregulates NCC through NEDD4-2 and prevents its activation by hypokalemia. Am J Physiol Renal Physiol 2019; 317:F825-F838. [PMID: 31364380 PMCID: PMC6843039 DOI: 10.1152/ajprenal.00216.2019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Hypomagnesemia is associated with reduced kidney function and life-threatening complications and sustains hypokalemia. The distal convoluted tubule (DCT) determines final urinary Mg2+ excretion and, via activity of the Na+-Cl- cotransporter (NCC), also plays a key role in K+ homeostasis by metering Na+ delivery to distal segments. Little is known about the mechanisms by which plasma Mg2+ concentration regulates NCC activity and how low-plasma Mg2+ concentration and K+ concentration interact to modulate NCC activity. To address this, we performed dietary manipulation studies in mice. Compared with normal diet, abundances of total NCC and phosphorylated NCC (pNCC) were lower after short-term (3 days) or long-term (14 days) dietary Mg2+ restriction. Altered NCC activation is unlikely to play a role, since we also observed lower total NCC abundance in mice lacking the two NCC-activating kinases, STE20/SPS-1-related proline/alanine-rich kinase and oxidative stress response kinase-1, after Mg2+ restriction. The E3 ubiquitin-protein ligase NEDD4-2 regulates NCC abundance during dietary NaCl loading or K+ restriction. Mg2+ restriction did not lower total NCC abundance in inducible nephron-specific neuronal precursor cell developmentally downregulated 4-2 (NEDD4-2) knockout mice. Total NCC and pNCC abundances were similar after short-term Mg2+ or combined Mg2+-K+ restriction but were dramatically lower compared with a low-K+ diet. Therefore, sustained NCC downregulation may serve a mechanism that enhances distal Na+ delivery during states of hypomagnesemia, maintaining hypokalemia. Similar results were obtained with long-term Mg2+-K+ restriction, but, surprisingly, NCC was not activated after long-term K+ restriction despite lower plasma K+ concentration, suggesting significant differences in distal tubule adaptation to acute or chronic K+ restriction.
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Affiliation(s)
- Mohammed Z. Ferdaus
- 1Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Anindit Mukherjee
- 1Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Jonathan W. Nelson
- 1Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Philip J. Blatt
- 1Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Lauren N. Miller
- 1Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Andrew S. Terker
- 2Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Olivier Staub
- 3Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Dao-Hong Lin
- 4Department of Pharmacology, New York Medical College, Valhalla, New York
| | - James A. McCormick
- 1Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
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95
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Wang X, Chen J, Shi S, Sheng S, Kleyman TR. Analyses of epithelial Na + channel variants reveal that an extracellular β-ball domain critically regulates ENaC gating. J Biol Chem 2019; 294:16765-16775. [PMID: 31551351 DOI: 10.1074/jbc.ra119.010001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 09/19/2019] [Indexed: 11/06/2022] Open
Abstract
Epithelial Na+ channel (ENaC)-mediated Na+ transport has a key role in the regulation of extracellular fluid volume, blood pressure, and extracellular [K+]. Among the thousands of human ENaC variants, only a few exist whose functional consequences have been experimentally tested. Here, we used the Xenopus oocyte expression system to investigate the functional roles of four nonsynonymous human ENaC variants located within the β7-strand and its adjacent loop of the α-subunit extracellular β-ball domain. αR350Wβγ and αG355Rβγ channels exhibited 2.5- and 1.8-fold greater amiloride-sensitive currents than WT αβγ human ENaCs, respectively, whereas αV351Aβγ channels conducted significantly less current than WT. Currents in αH354Rβγ-expressing oocytes were similar to those expressing WT. Surface expression levels of three mutants (αR350Wβγ, αV351Aβγ, and αG355Rβγ) were similar to that of WT. However, three mutant channels (αR350Wβγ, αH354Rβγ, and αG355Rβγ) exhibited a reduced Na+ self-inhibition response. Open probability of αR350Wβγ was significantly greater than that of WT. Moreover, other Arg-350 variants, including αR350G, αR350L, and αR350Q, also had significantly increased channel activity. A direct comparison of αR350W and two previously reported gain-of-function variants revealed that αR350W increases ENaC activity similarly to αW493R, but to a much greater degree than does αC479R. Our results indicate that αR350W along with αR350G, αR350L, and αR350Q, and αG355R are novel gain-of-function variants that function as gating modifiers. The location of these multiple functional variants suggests that the αENaC β-ball domain portion that interfaces with the palm domain of βENaC critically regulates ENaC gating.
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Affiliation(s)
- Xueqi Wang
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261.,Department of Nephrology, The Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China.,The Third Xiangya Hospital of Central South University, Changsha, Hunan 410013, China
| | - Jingxin Chen
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Shujie Shi
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Shaohu Sheng
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Thomas R Kleyman
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261.,Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261.,Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
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96
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Kim Y, Jun I, Shin DH, Yoon JG, Piao H, Jung J, Park HW, Cheng MH, Bahar I, Whitcomb DC, Lee MG. Regulation of CFTR Bicarbonate Channel Activity by WNK1: Implications for Pancreatitis and CFTR-Related Disorders. Cell Mol Gastroenterol Hepatol 2019; 9:79-103. [PMID: 31561038 PMCID: PMC6889609 DOI: 10.1016/j.jcmgh.2019.09.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 09/16/2019] [Accepted: 09/17/2019] [Indexed: 12/28/2022]
Abstract
BACKGRAOUD & AIMS Aberrant epithelial bicarbonate (HCO3-) secretion caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene is associated with several diseases including cystic fibrosis and pancreatitis. Dynamically regulated ion channel activity and anion selectivity of CFTR by kinases sensitive to intracellular chloride concentration ([Cl-]i) play an important role in epithelial HCO3- secretion. However, the molecular mechanisms of how [Cl-]i-dependent mechanisms regulate CFTR are unknown. METHODS We examined the mechanisms of the CFTR HCO3- channel regulation by [Cl-]i-sensitive kinases using an integrated electrophysiological, molecular, and computational approach including whole-cell, outside-out, and inside-out patch clamp recordings and molecular dissection of WNK1 and CFTR proteins. In addition, we analyzed the effects of pancreatitis-causing CFTR mutations on the WNK1-mediated regulation of CFTR. RESULTS Among the WNK1, SPAK, and OSR1 kinases that constitute a [Cl-]i-sensitive kinase cascade, the expression of WNK1 alone was sufficient to increase the CFTR bicarbonate permeability (PHCO3/PCl) and conductance (GHCO3) in patch clamp recordings. Molecular dissection of the WNK1 domains revealed that the WNK1 kinase domain is responsible for CFTR PHCO3/PCl regulation by direct association with CFTR, while the surrounding N-terminal regions mediate the [Cl-]i-sensitivity of WNK1. Furthermore, the pancreatitis-causing R74Q and R75Q mutations in the elbow helix 1 of CFTR hampered WNK1-CFTR physical associations and reduced WNK1-mediated CFTR PHCO3/PCl regulation. CONCLUSION The CFTR HCO3- channel activity is regulated by [Cl-]i and a WNK1-dependent mechanism. Our results provide new insights into the regulation of the ion selectivity of CFTR and the pathogenesis of CFTR-related disorders.
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Affiliation(s)
- Yonjung Kim
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Ikhyun Jun
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea,Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea
| | - Dong Hoon Shin
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Jihoon G. Yoon
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - He Piao
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Jinsei Jung
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea,Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Korea
| | - Hyun Woo Park
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea
| | - Mary Hongying Cheng
- Department of Computational & Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Ivet Bahar
- Department of Computational & Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - David C. Whitcomb
- Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Min Goo Lee
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea,Correspondence Address correspondence to: Min Goo Lee, Department of Pharmacology, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seoul 03722, Korea. fax: +82 2 313 1894.
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97
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Cornelius RJ, Ferdaus MZ, Nelson JW, McCormick JA. Cullin-Ring ubiquitin ligases in kidney health and disease. Curr Opin Nephrol Hypertens 2019; 28:490-497. [PMID: 31313673 PMCID: PMC6686897 DOI: 10.1097/mnh.0000000000000527] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE OF REVIEW Members of the Cullin family act as scaffolds in E3 ubiquitin ligases and play a central role in mediating protein degradation. Interactions with many different substrate-binding adaptors permit Cullin-containing E3 ligases to participate in diverse cellular functions. In the kidney, one well established target of Cullin-mediated degradation is the transcription factor Nrf2, a key player in responses to oxidative stress. The goal of this review is to discuss more recent findings revealing broader roles for Cullins in the kidney. RECENT FINDINGS Cullin 3 acts as the scaffold in the E3 ligase regulating Nrf2 abundance, but was more recently shown to be mutated in the disease familial hyperkalemic hypertension. Studies seeking to elucidate the molecular mechanisms by which Cullin 3 mutations lead to dysregulation of renal sodium transport will be discussed. Disruption of Cullin 3 in mice unexpectedly causes polyuria and fibrotic injury suggesting it has additional roles in the kidney. We will also review recent transcriptomic data suggesting that other Cullins are also likely to play important roles in renal function. SUMMARY Cullins form a large and diverse family of E3 ubiquitin ligases that are likely to have many important functions in the kidney.
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Affiliation(s)
- Ryan J. Cornelius
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR
| | - Mohammed Z. Ferdaus
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR
| | - Jonathan W. Nelson
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR
| | - James A. McCormick
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR
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98
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Blijdorp CJ, Hoorn EJ. Urinary extracellular vesicles: the mothership connection. Am J Physiol Renal Physiol 2019; 317:F648-F649. [DOI: 10.1152/ajprenal.00358.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- Charles J. Blijdorp
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Ewout J. Hoorn
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands
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99
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Mazumdar P, Pratama H, Lau SE, Teo CH, Harikrishna JA. Biology, phytochemical profile and prospects for snake fruit: An antioxidant-rich fruit of South East Asia. Trends Food Sci Technol 2019. [DOI: 10.1016/j.tifs.2019.06.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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100
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Wu P, Gao ZX, Zhang DD, Su XT, Wang WH, Lin DH. Deletion of Kir5.1 Impairs Renal Ability to Excrete Potassium during Increased Dietary Potassium Intake. J Am Soc Nephrol 2019; 30:1425-1438. [PMID: 31239388 PMCID: PMC6683724 DOI: 10.1681/asn.2019010025] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/24/2019] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The basolateral potassium channel in the distal convoluted tubule (DCT), comprising the inwardly rectifying potassium channel Kir4.1/Kir5.1 heterotetramer, plays a key role in mediating the effect of dietary potassium intake on the thiazide-sensitive NaCl cotransporter (NCC). The role of Kir5.1 (encoded by Kcnj16) in mediating effects of dietary potassium intake on the NCC and renal potassium excretion is unknown. METHODS We used electrophysiology, renal clearance, and immunoblotting to study Kir4.1 in the DCT and NCC in Kir5.1 knockout (Kcnj16-/- ) and wild-type (Kcnj16+/+ ) mice fed with normal, high, or low potassium diets. RESULTS We detected a 40-pS and 20-pS potassium channel in the basolateral membrane of the DCT in wild-type and knockout mice, respectively. Compared with wild-type, Kcnj16-/- mice fed a normal potassium diet had higher basolateral potassium conductance, a more negative DCT membrane potential, higher expression of phosphorylated NCC (pNCC) and total NCC (tNCC), and augmented thiazide-induced natriuresis. Neither high- nor low-potassium diets affected the basolateral DCT's potassium conductance and membrane potential in Kcnj16-/- mice. Although high potassium reduced and low potassium increased the expression of pNCC and tNCC in wild-type mice, these effects were absent in Kcnj16-/- mice. High potassium intake inhibited and low intake augmented thiazide-induced natriuresis in wild-type but not in Kcnj16-/- mice. Compared with wild-type, Kcnj16-/- mice with normal potassium intake had slightly lower plasma potassium but were more hyperkalemic with prolonged high potassium intake and more hypokalemic during potassium restriction. CONCLUSIONS Kir5.1 is essential for dietary potassium's effect on NCC and for maintaining potassium homeostasis.
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Affiliation(s)
- Peng Wu
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Zhong-Xiuzi Gao
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dan-Dan Zhang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Xiao-Tong Su
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York
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