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Huang YC, Liu CJ, Lu ZH, Huang HS. Long-Term Sodium Deficiency Reduces Sodium Excretion but Impairs Renal Function and Increases Stone Formation in Hyperoxaluric Calcium Oxalate Rats. Int J Mol Sci 2024; 25:3942. [PMID: 38612752 PMCID: PMC11011831 DOI: 10.3390/ijms25073942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Revised: 03/19/2024] [Accepted: 03/25/2024] [Indexed: 04/14/2024] Open
Abstract
Excessive sodium intake is associated with nephrolithiasis, but the impact of sodium-deficient (SD) diets is unknown. Hence, we investigated the effects of short- and long-term SD diets on the expression of renal aquaporins and sodium transporters, and thus calcium oxalate (CaOx) crystal formation in hyperoxaluria rats. In a short-term sodium balance study, six male rats received drinking water and six received 0.75% ethylene glycol (EG) to induce hyperoxaluria. After a 30-day period of feeding on normal chow, both groups were treated with a normal-sodium diet for 5 days, followed by a sodium-free diet for the next 5 days. In a long-term SD study (42 days), four groups, induced with EG or not, were treated with normal-sodium water and sodium-free drinking water, alternately. Short-term sodium restriction in EG rats reversed the daily positive sodium balance, but progressively caused a negative cumulative water balance. In the long-term study, the abundant levels of of Na/H exchanger, thiazide-sensitive Na-Cl cotransporter, Na-K-ATPase, and aquaporins-1 from SD + EG rats were markedly reduced, corresponding to a decrease in Uosm, as compared to SD rats. Increased urine calcium, AP(CaOx)index, and renal CaOx deposition were also noted in SD + EG rats. Although the SD treatment reduced sodium excretion, it also increased urinary calcium and impaired renal function, ultimately causing the formation of more CaOx crystals.
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Affiliation(s)
| | | | | | - Ho-Shiang Huang
- Department of Urology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 704302, Taiwan; (Y.-C.H.); (C.-J.L.); (Z.-H.L.)
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Sure F, Einsiedel J, Gmeiner P, Duchstein P, Zahn D, Korbmacher C, Ilyaskin AV. The small molecule activator S3969 stimulates the epithelial sodium channel by interacting with a specific binding pocket in the channel's β-subunit. J Biol Chem 2024; 300:105785. [PMID: 38401845 PMCID: PMC11065748 DOI: 10.1016/j.jbc.2024.105785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 01/13/2024] [Accepted: 02/19/2024] [Indexed: 02/26/2024] Open
Abstract
The epithelial sodium channel (ENaC) is essential for mediating sodium absorption in several epithelia. Its impaired function leads to severe disorders, including pseudohypoaldosteronism type 1 and respiratory distress. Therefore, pharmacological ENaC activators have potential therapeutic implications. Previously, a small molecule ENaC activator (S3969) was developed. So far, little is known about molecular mechanisms involved in S3969-mediated ENaC stimulation. Here, we identified an S3969-binding site in human ENaC by combining structure-based simulations with molecular biological methods and electrophysiological measurements of ENaC heterologously expressed in Xenopus laevis oocytes. We confirmed a previous observation that the extracellular loop of β-ENaC is essential for ENaC stimulation by S3969. Molecular dynamics simulations predicted critical residues in the thumb domain of β-ENaC (Arg388, Phe391, and Tyr406) that coordinate S3969 within a binding site localized at the β-γ-subunit interface. Importantly, mutating each of these residues reduced (R388H; R388A) or nearly abolished (F391G; Y406A) the S3969-mediated ENaC activation. Molecular dynamics simulations also suggested that S3969-mediated ENaC stimulation involved a movement of the α5 helix of the thumb domain of β-ENaC away from the palm domain of γ-ENaC. Consistent with this, the introduction of two cysteine residues (βR437C - γS298C) to form a disulfide bridge connecting these two domains prevented ENaC stimulation by S3969 unless the disulfide bond was reduced by DTT. Finally, we demonstrated that S3969 stimulated ENaC endogenously expressed in cultured human airway epithelial cells (H441). These new findings may lead to novel (patho-)physiological and therapeutic concepts for disorders associated with altered ENaC function.
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Affiliation(s)
- Florian Sure
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jürgen Einsiedel
- Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Patrick Duchstein
- Theoretical Chemistry/Computer Chemistry Center (CCC), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Dirk Zahn
- Theoretical Chemistry/Computer Chemistry Center (CCC), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Christoph Korbmacher
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Alexandr V Ilyaskin
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
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Hu Y, Bao J, Gao Z, Ye L, Wang L. Sodium-Glucose Cotransporter Protein 2 Inhibitors: Novel Application for the Treatment of Obesity-Associated Hypertension. Diabetes Metab Syndr Obes 2024; 17:407-415. [PMID: 38292009 PMCID: PMC10826576 DOI: 10.2147/dmso.s446904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 01/13/2024] [Indexed: 02/01/2024] Open
Abstract
Obesity is becoming increasingly prevalent in China and worldwide and is closely related to the development of hypertension. The pathophysiology of obesity-associated hypertension is complex, including an overactive sympathetic nervous system (SNS), activation of the renin-angiotensin-aldosterone system (RAAS), insulin resistance, hyperleptinemia, renal dysfunction, inflammatory responses, and endothelial function, which complicates treatment. Sodium-glucose cotransporter protein 2 (SGLT-2) inhibitors, novel hypoglycemic agents, have been shown to reduce body weight and blood pressure and may serve as potential novel agents for the treatment of obesity-associated hypertension. This review discusses the beneficial mechanisms of SGLT-2 inhibitors for the treatment of obesity-associated hypertension. SGLT-2 inhibitors can inhibit SNS activity, reduce RAAS activation, ameliorate insulin resistance, reduce leptin secretion, improve renal function, and inhibit inflammatory responses. SGLT-2 inhibitors can, therefore, simultaneously target multiple mechanisms of obesity-associated hypertension and may serve as an effective treatment for obesity-associated hypertension.
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Affiliation(s)
- Yilan Hu
- The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, People’s Republic of China
- Heart Center, Department of Cardiovascular Medicine, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, People’s Republic of China
| | - Jiaqi Bao
- The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, People’s Republic of China
- Heart Center, Department of Cardiovascular Medicine, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, People’s Republic of China
| | - Zhicheng Gao
- The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, People’s Republic of China
- Heart Center, Department of Cardiovascular Medicine, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, People’s Republic of China
| | - Lifang Ye
- Heart Center, Department of Cardiovascular Medicine, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, People’s Republic of China
| | - Lihong Wang
- The Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, People’s Republic of China
- Heart Center, Department of Cardiovascular Medicine, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, People’s Republic of China
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Thompson JA, Kashon ML, McKinney W, Fedan JS. High-fat Western diet alters crystalline silica-induced airway epithelium ion transport but not airway smooth muscle reactivity. BMC Res Notes 2024; 17:13. [PMID: 38172968 PMCID: PMC10765734 DOI: 10.1186/s13104-023-06672-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 12/13/2023] [Indexed: 01/05/2024] Open
Abstract
OBJECTIVES Silicosis is an irreversible occupational lung disease resulting from crystalline silica inhalation. Previously, we discovered that Western diet (HFWD)-consumption increases susceptibility to silica-induced pulmonary inflammation and fibrosis. This study investigated the potential of HFWD to alter silica-induced effects on airway epithelial ion transport and smooth muscle reactivity. METHODS Six-week-old male F344 rats were fed a HFWD or standard rat chow (STD) and exposed to silica (Min-U-Sil 5®, 15 mg/m3, 6 h/day, 5 days/week, for 39 d) or filtered air. Experimental endpoints were measured at 0, 4, and 8 weeks post-exposure. Transepithelial potential difference (Vt), short-circuit current (ISC) and transepithelial resistance (Rt) were measured in tracheal segments and ion transport inhibitors [amiloride, Na+ channel blocker; NPPB; Cl- channel blocker; ouabain, Na+, K+-pump blocker] identified changes in ion transport pathways. Changes in airway smooth muscle reactivity to methacholine (MCh) were investigated in the isolated perfused trachea preparation. RESULTS Silica reduced basal ISC at 4 weeks and HFWD reduced the ISC response to amiloride at 0 week compared to air control. HFWD + silica exposure induced changes in ion transport 0 and 4 weeks after treatment compared to silica or HFWD treatments alone. No effects on airway smooth muscle reactivity to MCh were observed.
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Affiliation(s)
- Janet A Thompson
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505, USA.
- Pathology and Physiology Research Branch, National Institute for Occupational Safety and Health, 1000 Frederick Lane, Morgantown, WV, 26508, USA.
| | - Michael L Kashon
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505, USA
| | - Walter McKinney
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505, USA
| | - Jeffrey S Fedan
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505, USA
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Saha B, Shabbir W, Takagi E, Duan XP, Leite Dellova DCA, Demko J, Manis A, Loffing-Cueni D, Loffing J, Sørensen MV, Wang WH, Pearce D. Potassium Activates mTORC2-dependent SGK1 Phosphorylation to Stimulate Epithelial Sodium Channel: Role in Rapid Renal Responses to Dietary Potassium. J Am Soc Nephrol 2023; 34:1019-1038. [PMID: 36890646 PMCID: PMC10278851 DOI: 10.1681/asn.0000000000000109] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 02/06/2023] [Indexed: 03/10/2023] Open
Abstract
SIGNIFICANCE STATEMENT Rapid renal responses to ingested potassium are essential to prevent hyperkalemia and also play a central role in blood pressure regulation. Although local extracellular K + concentration in kidney tissue is increasingly recognized as an important regulator of K + secretion, the underlying mechanisms that are relevant in vivo remain controversial. To assess the role of the signaling kinase mTOR complex-2 (mTORC2), the authors compared the effects of K + administered by gavage in wild-type mice and knockout mice with kidney tubule-specific inactivation of mTORC2. They found that mTORC2 is rapidly activated to trigger K + secretion and maintain electrolyte homeostasis. Downstream targets of mTORC2 implicated in epithelial sodium channel regulation (SGK1 and Nedd4-2) were concomitantly phosphorylated in wild-type, but not knockout, mice. These findings offer insight into electrolyte physiologic and regulatory mechanisms. BACKGROUND Increasing evidence implicates the signaling kinase mTOR complex-2 (mTORC2) in rapid renal responses to changes in plasma potassium concentration [K + ]. However, the underlying cellular and molecular mechanisms that are relevant in vivo for these responses remain controversial. METHODS We used Cre-Lox-mediated knockout of rapamycin-insensitive companion of TOR (Rictor) to inactivate mTORC2 in kidney tubule cells of mice. In a series of time-course experiments in wild-type and knockout mice, we assessed urinary and blood parameters and renal expression and activity of signaling molecules and transport proteins after a K + load by gavage. RESULTS A K + load rapidly stimulated epithelial sodium channel (ENaC) processing, plasma membrane localization, and activity in wild-type, but not in knockout, mice. Downstream targets of mTORC2 implicated in ENaC regulation (SGK1 and Nedd4-2) were concomitantly phosphorylated in wild-type, but not knockout, mice. We observed differences in urine electrolytes within 60 minutes, and plasma [K + ] was greater in knockout mice within 3 hours of gavage. Renal outer medullary potassium (ROMK) channels were not acutely stimulated in wild-type or knockout mice, nor were phosphorylation of other mTORC2 substrates (PKC and Akt). CONCLUSIONS The mTORC2-SGK1-Nedd4-2-ENaC signaling axis is a key mediator of rapid tubule cell responses to increased plasma [K + ] in vivo . The effects of K + on this signaling module are specific, in that other downstream mTORC2 targets, such as PKC and Akt, are not acutely affected, and ROMK and Large-conductance K + (BK) channels are not activated. These findings provide new insight into the signaling network and ion transport systems that underlie renal responses to K +in vivo .
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Affiliation(s)
- Bidisha Saha
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | - Waheed Shabbir
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | - Enzo Takagi
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | - Xin-Peng Duan
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Deise Carla Almeida Leite Dellova
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
- Current address: Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga, Sao Paulo, Brazil
| | - John Demko
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | - Anna Manis
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | | | | | - Mads Vaarby Sørensen
- Department of Biomedicine, Unit of Physiology, Aarhus University, Aarhus, Denmark
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - David Pearce
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
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Ahmad T, Ertuglu LA, Masenga SK, Kleyman TR, Kirabo A. The epithelial sodium channel in inflammation and blood pressure modulation. Front Cardiovasc Med 2023; 10:1130148. [PMID: 37123470 PMCID: PMC10132033 DOI: 10.3389/fcvm.2023.1130148] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 03/24/2023] [Indexed: 05/02/2023] Open
Abstract
A major regulator of blood pressure and volume homeostasis in the kidney is the epithelial sodium channel (ENaC). ENaC is composed of alpha(α)/beta(β)/gamma(γ) or delta(δ)/beta(β)/gamma(γ) subunits. The δ subunit is functional in the guinea pig, but not in routinely used experimental rodent models including rat or mouse, and thus remains the least understood of the four subunits. While the δ subunit is poorly expressed in the human kidney, we recently found that its gene variants are associated with blood pressure and kidney function. The δ subunit is expressed in the human vasculature where it may influence vascular function. Moreover, we recently found that the δ subunit is also expressed human antigen presenting cells (APCs). Our studies indicate that extracellular Na+ enters APCs via ENaC leading to inflammation and salt-induced hypertension. In this review, we highlight recent findings on the role of extra-renal ENaC in inflammation, vascular dysfunction, and blood pressure modulation. Targeting extra-renal ENaC may provide new drug therapies for salt-induced hypertension.
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Affiliation(s)
- Taseer Ahmad
- Department of Pharmacology, College of Pharmacy, University of Sargodha, Sargodha, Pakistan
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Lale A. Ertuglu
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Sepiso K. Masenga
- Department of Physiological Sciences, School of Medicine and Health Sciences, Mulungushi University, Livingstone, Zambia
| | - Thomas R. Kleyman
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, United States
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, United States
| | - Annet Kirabo
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
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Loughlin S, Costello HM, Roe AJ, Buckley C, Wilson SM, Bailey MA, Mansley MK. Mapping the Transcriptome Underpinning Acute Corticosteroid Action within the Cortical Collecting Duct. KIDNEY360 2023; 4:226-240. [PMID: 36821614 PMCID: PMC10103384 DOI: 10.34067/kid.0003582022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 11/08/2022] [Indexed: 11/10/2022]
Abstract
Key Points We report the transcriptomes associated with acute corticosteroid regulation of ENaC activity in polarized mCCDcl1 collecting duct cells. Nine genes were regulated by aldosterone (ALDO), 0 with corticosterone alone, and 151 with corticosterone when 11βHSD2 activity was inhibited. We validated three novel ALDO-induced genes, Rasd1 , Sult1d1 , and Gm43305 , in primary cells isolated from a novel principal cell reporter mouse. Background Corticosteroids regulate distal nephron and collecting duct (CD) Na+ reabsorption, contributing to fluid-volume and blood pressure homeostasis. The transcriptional landscape underpinning the acute stimulation of the epithelial sodium channel (ENaC) by physiological concentrations of corticosteroids remains unclear. Methods Transcriptomic profiles underlying corticosteroid-stimulated ENaC activity in polarized mCCDcl1 cells were generated by coupling electrophysiological measurements of amiloride-sensitive currents with RNAseq. Generation of a principal cell-specific reporter mouse line, mT/mG -Aqp2Cre, enabled isolation of primary CD principal cells by FACS, and ENaC activity was measured in cultured primary cells after acute application of corticosteroids. Expression of target genes was assessed by qRT-PCR in cultured cells or freshly isolated cells after the acute elevation of steroid hormones in mT/mG -Aqp2Cre mice. Results Physiological relevance of the mCCDcl1 model was confirmed with aldosterone (ALDO)-specific stimulation of SGK1 and ENaC activity. Corticosterone (CORT) only modulated these responses at supraphysiological concentrations or when 11βHSD2 was inhibited. When 11βHSD2 protection was intact, CORT caused no significant change in transcripts. We identified a small number of ALDO-induced transcripts associated with stimulated ENaC activity in mCCDcl1 cells and a much larger number with CORT in the absence of 11βHSD2 activity. Principal cells isolated from mT/mG -Aqp2Cre mice were validated and assessment of identified ALDO-induced genes revealed that Sgk1 , Zbtbt16 , Sult1d1 , Rasd1 , and Gm43305 are acutely upregulated by corticosteroids both in vitro and in vivo . Conclusions This study reports the transcriptome of mCCDcl1 cells and identifies a small number of ALDO-induced genes associated with acute stimulation of ENaC, including three previously undescribed genes.
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Affiliation(s)
- Struan Loughlin
- Cellular Medicine Research Division, University of St Andrews, St Andrews, United Kingdom
- Centre for Cardiovascular Science, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Hannah M. Costello
- Centre for Cardiovascular Science, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew J. Roe
- Division of Pharmacy, School of Medicine, Pharmacy and Health, Durham University Queen's Campus, Stockton-on-Tees, United Kingdom
| | - Charlotte Buckley
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Stuart M. Wilson
- Division of Pharmacy, School of Medicine, Pharmacy and Health, Durham University Queen's Campus, Stockton-on-Tees, United Kingdom
| | - Matthew A. Bailey
- Centre for Cardiovascular Science, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Morag K. Mansley
- Cellular Medicine Research Division, University of St Andrews, St Andrews, United Kingdom
- Centre for Cardiovascular Science, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
- Division of Pharmacy, School of Medicine, Pharmacy and Health, Durham University Queen's Campus, Stockton-on-Tees, United Kingdom
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Cardiovascular Disease in Obstructive Sleep Apnea: Putative Contributions of Mineralocorticoid Receptors. Int J Mol Sci 2023; 24:ijms24032245. [PMID: 36768567 PMCID: PMC9916750 DOI: 10.3390/ijms24032245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/12/2023] [Accepted: 01/20/2023] [Indexed: 01/24/2023] Open
Abstract
Obstructive sleep apnea (OSA) is a chronic and highly prevalent condition that is associated with oxidative stress, inflammation, and fibrosis, leading to endothelial dysfunction, arterial stiffness, and vascular insulin resistance, resulting in increased cardiovascular disease and overall mortality rates. To date, OSA remains vastly underdiagnosed and undertreated, with conventional treatments yielding relatively discouraging results for improving cardiovascular outcomes in OSA patients. As such, a better mechanistic understanding of OSA-associated cardiovascular disease (CVD) and the development of novel adjuvant therapeutic targets are critically needed. It is well-established that inappropriate mineralocorticoid receptor (MR) activation in cardiovascular tissues plays a causal role in a multitude of CVD states. Clinical studies and experimental models of OSA lead to increased secretion of the MR ligand aldosterone and excessive MR activation. Furthermore, MR activation has been associated with worsened OSA prognosis. Despite these documented relationships, there have been no studies exploring the causal involvement of MR signaling in OSA-associated CVD. Further, scarce clinical studies have exclusively assessed the beneficial role of MR antagonists for the treatment of systemic hypertension commonly associated with OSA. Here, we provide a comprehensive overview of overlapping mechanistic pathways recruited in the context of MR activation- and OSA-induced CVD and propose MR-targeted therapy as a potential avenue to abrogate the deleterious cardiovascular consequences of OSA.
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Diakov A, Nesterov V, Dahlmann A, Korbmacher C. Two adjacent phosphorylation sites in the C-terminus of the channel's α-subunit have opposing effects on epithelial sodium channel (ENaC) activity. Pflugers Arch 2022; 474:681-697. [PMID: 35525869 PMCID: PMC9192390 DOI: 10.1007/s00424-022-02693-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 04/25/2022] [Indexed: 02/07/2023]
Abstract
How phosphorylation of the epithelial sodium channel (ENaC) contributes to its regulation is incompletely understood. Previously, we demonstrated that in outside-out patches ENaC activation by serum- and glucocorticoid-inducible kinase isoform 1 (SGK1) was abolished by mutating a serine residue in a putative SGK1 consensus motif RXRXX(S/T) in the channel’s α-subunit (S621 in rat). Interestingly, this serine residue is followed by a highly conserved proline residue rather than by a hydrophobic amino acid thought to be required for a functional SGK1 consensus motif according to invitro data. This suggests that this serine residue is a potential phosphorylation site for the dual-specificity tyrosine phosphorylated and regulated kinase 2 (DYRK2), a prototypical proline-directed kinase. Its phosphorylation may prime a highly conserved preceding serine residue (S617 in rat) to be phosphorylated by glycogen synthase kinase 3 β (GSK3β). Therefore, we investigated the effect of DYRK2 on ENaC activity in outside-out patches of Xenopus laevis oocytes heterologously expressing rat ENaC. DYRK2 included in the pipette solution significantly increased ENaC activity. In contrast, GSK3β had an inhibitory effect. Replacing S621 in αENaC with alanine (S621A) abolished the effects of both kinases. A S617A mutation reduced the inhibitory effect of GKS3β but did not prevent ENaC activation by DYRK2. Our findings suggest that phosphorylation of S621 activates ENaC and primes S617 for subsequent phosphorylation by GSK3β resulting in channel inhibition. In proof-of-concept experiments, we demonstrated that DYRK2 can also stimulate ENaC currents in microdissected mouse distal nephron, whereas GSK3β inhibits the currents.
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Affiliation(s)
- Alexei Diakov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstr, 6, 91054, Erlangen, Germany
| | - Viatcheslav Nesterov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstr, 6, 91054, Erlangen, Germany
| | - Anke Dahlmann
- Medizinische Klinik 4 - Nephrologie und Hypertensiologie, Universitätsklinikum Erlangen, Ulmenweg 18, 91054, Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstr, 6, 91054, Erlangen, Germany.
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10
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Sure F, Bertog M, Afonso S, Diakov A, Rinke R, Madej MG, Wittmann S, Gramberg T, Korbmacher C, Ilyaskin AV. Transmembrane serine protease 2 (TMPRSS2) proteolytically activates the epithelial sodium channel (ENaC) by cleaving the channel's γ-subunit. J Biol Chem 2022; 298:102004. [PMID: 35504352 PMCID: PMC9163703 DOI: 10.1016/j.jbc.2022.102004] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 04/21/2022] [Accepted: 04/27/2022] [Indexed: 01/09/2023] Open
Abstract
The epithelial sodium channel (ENaC) is a heterotrimer consisting of α-, β-, and γ-subunits. Channel activation requires proteolytic release of inhibitory tracts from the extracellular domains of α-ENaC and γ-ENaC; however, the proteases involved in the removal of the γ-inhibitory tract remain unclear. In several epithelial tissues, ENaC is coexpressed with the transmembrane serine protease 2 (TMPRSS2). Here, we explored the effect of human TMPRSS2 on human αβγ-ENaC heterologously expressed in Xenopus laevis oocytes. We found that coexpression of TMPRSS2 stimulated ENaC-mediated whole-cell currents by approximately threefold, likely because of an increase in average channel open probability. Furthermore, TMPRSS2-dependent ENaC stimulation was not observed using a catalytically inactive TMPRSS2 mutant and was associated with fully cleaved γ-ENaC in the intracellular and cell surface protein fractions. This stimulatory effect of TMPRSS2 on ENaC was partially preserved when inhibiting its proteolytic activity at the cell surface using aprotinin but was abolished when the γ-inhibitory tract remained attached to its binding site following introduction of two cysteine residues (S155C–Q426C) to form a disulfide bridge. In addition, computer simulations and site-directed mutagenesis experiments indicated that TMPRSS2 can cleave γ-ENaC at sites both proximal and distal to the γ-inhibitory tract. This suggests a dual role of TMPRSS2 in the proteolytic release of the γ-inhibitory tract. Finally, we demonstrated that TMPRSS2 knockdown in cultured human airway epithelial cells (H441) reduced baseline proteolytic activation of endogenously expressed ENaC. Thus, we conclude that TMPRSS2 is likely to contribute to proteolytic ENaC activation in epithelial tissues in vivo.
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Affiliation(s)
- Florian Sure
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - Marko Bertog
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - Sara Afonso
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - Alexei Diakov
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - Ralf Rinke
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
| | - M Gregor Madej
- Department of Biophysics II/Structural Biology, University of Regensburg, Regensburg, Germany
| | - Sabine Wittmann
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsklinikum Erlangen, Institute of Clinical and Molecular Virology, Erlangen, Germany
| | - Thomas Gramberg
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsklinikum Erlangen, Institute of Clinical and Molecular Virology, Erlangen, Germany
| | - Christoph Korbmacher
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany.
| | - Alexandr V Ilyaskin
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Cellular and Molecular Physiology, Erlangen, Germany
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11
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Vu TA, Lema I, Hani I, Cheval L, Atger-Lallier L, Souvannarath V, Perrot J, Souvanheuane M, Marie Y, Fabrega S, Blanchard A, Bouligand J, Kamenickỷ P, Crambert G, Martinerie L, Lombès M, Viengchareun S. miR-324-5p and miR-30c-2-3p Alter Renal Mineralocorticoid Receptor Signaling under Hypertonicity. Cells 2022; 11:cells11091377. [PMID: 35563683 PMCID: PMC9104010 DOI: 10.3390/cells11091377] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/04/2022] [Accepted: 04/12/2022] [Indexed: 11/16/2022] Open
Abstract
The Mineralocorticoid Receptor (MR) mediates the sodium-retaining action of aldosterone in the distal nephron, but mechanisms regulating MR expression are still poorly understood. We previously showed that RNA Binding Proteins (RBPs) regulate MR expression at the post-transcriptional level in response to variations of extracellular tonicity. Herein, we highlight a novel regulatory mechanism involving the recruitment of microRNAs (miRNAs) under hypertonicity. RT-qPCR validated miRNAs candidates identified by high throughput screening approaches and transfection of a luciferase reporter construct together with miRNAs Mimics or Inhibitors demonstrated their functional interaction with target transcripts. Overexpression strategies using Mimics or lentivirus revealed the impact on MR expression and signaling in renal KC3AC1 cells. miR-324-5p and miR-30c-2-3p expression are increased under hypertonicity in KC3AC1 cells. These miRNAs directly affect Nr3c2 (MR) transcript stability, act with Tis11b to destabilize MR transcript but also repress Elavl1 (HuR) transcript, which enhances MR expression and signaling. Overexpression of miR-324-5p and miR-30c-2-3p alter MR expression and signaling in KC3AC1 cells with blunted responses in terms of aldosterone-regulated genes expression. We also confirm that their expression is increased by hypertonicity in vivo in the kidneys of mice treated with furosemide. These findings may have major implications for the pathogenesis of renal dysfunctions, sodium retention, and mineralocorticoid resistance.
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Affiliation(s)
- Thi An Vu
- Physiologie et Physiopathologie Endocriniennes, Université Paris-Saclay, Inserm, 94276 Le Kremlin-Bicêtre, France; (T.A.V.); (I.L.); (I.H.); (L.A.-L.); (V.S.); (J.P.); (M.S.); (J.B.); (P.K.); (L.M.); (M.L.)
| | - Ingrid Lema
- Physiologie et Physiopathologie Endocriniennes, Université Paris-Saclay, Inserm, 94276 Le Kremlin-Bicêtre, France; (T.A.V.); (I.L.); (I.H.); (L.A.-L.); (V.S.); (J.P.); (M.S.); (J.B.); (P.K.); (L.M.); (M.L.)
| | - Imene Hani
- Physiologie et Physiopathologie Endocriniennes, Université Paris-Saclay, Inserm, 94276 Le Kremlin-Bicêtre, France; (T.A.V.); (I.L.); (I.H.); (L.A.-L.); (V.S.); (J.P.); (M.S.); (J.B.); (P.K.); (L.M.); (M.L.)
| | - Lydie Cheval
- Centre de Recherche des Cordeliers, Inserm, Sorbonne Université, Université Paris Cité, 75006 Paris, France; (L.C.); (G.C.)
| | - Laura Atger-Lallier
- Physiologie et Physiopathologie Endocriniennes, Université Paris-Saclay, Inserm, 94276 Le Kremlin-Bicêtre, France; (T.A.V.); (I.L.); (I.H.); (L.A.-L.); (V.S.); (J.P.); (M.S.); (J.B.); (P.K.); (L.M.); (M.L.)
| | - Vilayvane Souvannarath
- Physiologie et Physiopathologie Endocriniennes, Université Paris-Saclay, Inserm, 94276 Le Kremlin-Bicêtre, France; (T.A.V.); (I.L.); (I.H.); (L.A.-L.); (V.S.); (J.P.); (M.S.); (J.B.); (P.K.); (L.M.); (M.L.)
| | - Julie Perrot
- Physiologie et Physiopathologie Endocriniennes, Université Paris-Saclay, Inserm, 94276 Le Kremlin-Bicêtre, France; (T.A.V.); (I.L.); (I.H.); (L.A.-L.); (V.S.); (J.P.); (M.S.); (J.B.); (P.K.); (L.M.); (M.L.)
| | - Mélanie Souvanheuane
- Physiologie et Physiopathologie Endocriniennes, Université Paris-Saclay, Inserm, 94276 Le Kremlin-Bicêtre, France; (T.A.V.); (I.L.); (I.H.); (L.A.-L.); (V.S.); (J.P.); (M.S.); (J.B.); (P.K.); (L.M.); (M.L.)
| | - Yannick Marie
- Plateforme de Genotypage Séquençage (iGenSeq), Institut du Cerveau et de la Moelle Epinière, Hôpital Sapêtrière, 75013 Paris, France;
| | - Sylvie Fabrega
- Plateforme Vecteurs Viraux et Transfert de Gènes, Structure Federative de Recherche Necker, UMS 24, UMS 3633, Faculté de Santé, Université Paris Cité, 75015 Paris, France;
| | - Anne Blanchard
- Inserm, Centre d’Investigations Cliniques 9201, 75015 Paris, France;
| | - Jérôme Bouligand
- Physiologie et Physiopathologie Endocriniennes, Université Paris-Saclay, Inserm, 94276 Le Kremlin-Bicêtre, France; (T.A.V.); (I.L.); (I.H.); (L.A.-L.); (V.S.); (J.P.); (M.S.); (J.B.); (P.K.); (L.M.); (M.L.)
- Assistance Publique-Hôpitaux de Paris, Hôpital Bicêtre, Service de Génétique Moléculaire, Pharmacogénétique et Hormonologie, 94275 Le Kremlin-Bicêtre, France
| | - Peter Kamenickỷ
- Physiologie et Physiopathologie Endocriniennes, Université Paris-Saclay, Inserm, 94276 Le Kremlin-Bicêtre, France; (T.A.V.); (I.L.); (I.H.); (L.A.-L.); (V.S.); (J.P.); (M.S.); (J.B.); (P.K.); (L.M.); (M.L.)
- Assistance Publique-Hopitaux de Paris, Hôpital Bicêtre, Service d’Endocrinologie et des Maladies de la Reproduction, 94275 Le Kremlin-Bicêtre, France
| | - Gilles Crambert
- Centre de Recherche des Cordeliers, Inserm, Sorbonne Université, Université Paris Cité, 75006 Paris, France; (L.C.); (G.C.)
| | - Laetitia Martinerie
- Physiologie et Physiopathologie Endocriniennes, Université Paris-Saclay, Inserm, 94276 Le Kremlin-Bicêtre, France; (T.A.V.); (I.L.); (I.H.); (L.A.-L.); (V.S.); (J.P.); (M.S.); (J.B.); (P.K.); (L.M.); (M.L.)
- Assistance-Publique Hôpitaux de Paris, Hôpital Robert Debré, Service d’Endocrinologie Pédiatrique, Université Paris Cité, 75019 Paris, France
| | - Marc Lombès
- Physiologie et Physiopathologie Endocriniennes, Université Paris-Saclay, Inserm, 94276 Le Kremlin-Bicêtre, France; (T.A.V.); (I.L.); (I.H.); (L.A.-L.); (V.S.); (J.P.); (M.S.); (J.B.); (P.K.); (L.M.); (M.L.)
| | - Say Viengchareun
- Physiologie et Physiopathologie Endocriniennes, Université Paris-Saclay, Inserm, 94276 Le Kremlin-Bicêtre, France; (T.A.V.); (I.L.); (I.H.); (L.A.-L.); (V.S.); (J.P.); (M.S.); (J.B.); (P.K.); (L.M.); (M.L.)
- Correspondence:
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12
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Keely SJ, Urso A, Ilyaskin AV, Korbmacher C, Bunnett NW, Poole DP, Carbone SE. Contributions of bile acids to gastrointestinal physiology as receptor agonists and modifiers of ion channels. Am J Physiol Gastrointest Liver Physiol 2022; 322:G201-G222. [PMID: 34755536 PMCID: PMC8782647 DOI: 10.1152/ajpgi.00125.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 10/28/2021] [Accepted: 11/08/2021] [Indexed: 02/03/2023]
Abstract
Bile acids (BAs) are known to be important regulators of intestinal motility and epithelial fluid and electrolyte transport. Over the past two decades, significant advances in identifying and characterizing the receptors, transporters, and ion channels targeted by BAs have led to exciting new insights into the molecular mechanisms involved in these processes. Our appreciation of BAs, their receptors, and BA-modulated ion channels as potential targets for the development of new approaches to treat intestinal motility and transport disorders is increasing. In the current review, we aim to summarize recent advances in our knowledge of the different BA receptors and BA-modulated ion channels present in the gastrointestinal system. We discuss how they regulate motility and epithelial transport, their roles in pathogenesis, and their therapeutic potential in a range of gastrointestinal diseases.
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Affiliation(s)
- Stephen J Keely
- Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, Ireland
| | - Andreacarola Urso
- Department of Surgery, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York
- Department of Pharmacology, Columbia University, New York, New York
| | - Alexandr V Ilyaskin
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Bavaria, Germany
| | - Christoph Korbmacher
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Bavaria, Germany
| | - Nigel W Bunnett
- Department of Molecular Pathobiology, Neuroscience Institute, New York University, New York, New York
- Department of Neuroscience and Physiology, Neuroscience Institute, New York University, New York, New York
| | - Daniel P Poole
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Australian Research Council, Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Simona E Carbone
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Australian Research Council, Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
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13
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Pearce D, Manis AD, Nesterov V, Korbmacher C. Regulation of distal tubule sodium transport: mechanisms and roles in homeostasis and pathophysiology. Pflugers Arch 2022; 474:869-884. [PMID: 35895103 PMCID: PMC9338908 DOI: 10.1007/s00424-022-02732-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/09/2022] [Accepted: 07/11/2022] [Indexed: 02/03/2023]
Abstract
Regulated Na+ transport in the distal nephron is of fundamental importance to fluid and electrolyte homeostasis. Further upstream, Na+ is the principal driver of secondary active transport of numerous organic and inorganic solutes. In the distal nephron, Na+ continues to play a central role in controlling the body levels and concentrations of a more select group of ions, including K+, Ca++, Mg++, Cl-, and HCO3-, as well as water. Also, of paramount importance are transport mechanisms aimed at controlling the total level of Na+ itself in the body, as well as its concentrations in intracellular and extracellular compartments. Over the last several decades, the transporters involved in moving Na+ in the distal nephron, and directly or indirectly coupling its movement to that of other ions have been identified, and their interrelationships brought into focus. Just as importantly, the signaling systems and their components-kinases, ubiquitin ligases, phosphatases, transcription factors, and others-have also been identified and many of their actions elucidated. This review will touch on selected aspects of ion transport regulation, and its impact on fluid and electrolyte homeostasis. A particular focus will be on emerging evidence for site-specific regulation of the epithelial sodium channel (ENaC) and its role in both Na+ and K+ homeostasis. In this context, the critical regulatory roles of aldosterone, the mineralocorticoid receptor (MR), and the kinases SGK1 and mTORC2 will be highlighted. This includes a discussion of the newly established concept that local K+ concentrations are involved in the reciprocal regulation of Na+-Cl- cotransporter (NCC) and ENaC activity to adjust renal K+ secretion to dietary intake.
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Affiliation(s)
- David Pearce
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA USA
| | - Anna D. Manis
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA USA
| | - Viatcheslav Nesterov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, Erlangen, Germany
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14
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Nakazawa T, Yamaguchi Y, Fukunaga Y, Tamura K. A possible critical dosing period of p-cumylphenol for development of cystic kidneys in rat neonates. J Toxicol Pathol 2022; 35:123-127. [PMID: 35221506 PMCID: PMC8828611 DOI: 10.1293/tox.2021-0010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 08/30/2021] [Indexed: 11/19/2022] Open
Abstract
In accordance with a previous report on cystic kidneys induced in rat neonates when
dosed with p-cumylphenol (PCP) for 18 days from postnatal day (PND) 4, 3 rat neonates were
dosed with PCP once a day for 14 days, either from PND 14, 21, 28, 35, or 42 as W2, W3,
W4, W5, and W6 groups, respectively, to investigate whether dosing periods in different
PNDs influenced the development of cystic renal tubules. The lesion was striking in the W2
group and at a lesser magnitude in the W3 group, whereas either kidney was unaffected when
dosing was initiated beyond PND 28. These findings, together with the results from the
previous study, suggested that PND 14-28 is a critical dosing period for PCP to develop
cystic kidneys in rat neonates. The lining epithelium of the cystic tubules was
immunohistochemically positive for AQP2. This finding and the anatomical location
indicated that the cystic tubules were of collecting duct origin. Either obstruction,
fluid accumulation, or reparative hyperplasia of the lining epithelium was unlikely to be
involved in the formation of cystic tubules lined with a monolayer of cuboidal or columnar
epithelium with a high nuclear density. Thus, the follow-up investigation on PCP suggested
a critical dosing period of PND 14-28 in rat neonates for the development of cystic
dilation of renal collecting ducts. This study further supports that additive hyperplasia
of the lining epithelium is a fundamental basis of this unique lesion.
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Affiliation(s)
- Tomomi Nakazawa
- Pathology Division, Tsukuba Research Institute, Bozo Research Center Inc., 8 Okubo, Tsukuba-shi, Ibaraki 300-2611, Japan
| | - Yuko Yamaguchi
- Pathology Division, Gotemba Research Institute, Bozo Research Center Inc., 1284 Kamado, Gotemba, Shizuoka 412-0039, Japan
| | - Yachiyo Fukunaga
- Pathology Division, Tsukuba Research Institute, Bozo Research Center Inc., 8 Okubo, Tsukuba-shi, Ibaraki 300-2611, Japan
| | - Kazutoshi Tamura
- Pathology Division, Gotemba Research Institute, Bozo Research Center Inc., 1284 Kamado, Gotemba, Shizuoka 412-0039, Japan
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15
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Nesterov V, Bertog M, Korbmacher C. High baseline ROMK activity in the mouse late distal convoluted and early connecting tubule probably contributes to aldosterone-independent K + secretion. Am J Physiol Renal Physiol 2022; 322:F42-F54. [PMID: 34843658 DOI: 10.1152/ajprenal.00252.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 11/18/2021] [Indexed: 11/22/2022] Open
Abstract
The renal outer medullary K+ channel (ROMK) is colocalized with the epithelial Na+ channel (ENaC) in the late distal convoluted tubule (DCT2), connecting tubule (CNT), and cortical collecting duct (CCD). ENaC-mediated Na+ absorption generates the electrical driving force for ROMK-mediated tubular K+ secretion, which is critically important for maintaining renal K+ homeostasis. ENaC activity is aldosterone dependent in the late CNT and early CCD (CNT/CCD) but aldosterone independent in the DCT2 and early CNT (DCT2/CNT). This suggests that under baseline conditions with low plasma aldosterone, ROMK-mediated K+ secretion mainly occurs in the DCT2/CNT. Therefore, we hypothesized that baseline ROMK activity is higher in the DCT2/CNT than in the CNT/CCD. To test this hypothesis, patch-clamp experiments were performed in the DCT2/CNT and CNT/CCD microdissected from mice maintained on a standard diet. In single-channel recordings from outside-out patches, we detected typical ROMK channel activity in both the DCT2/CNT and CNT/CCD and confirmed that ROMK is the predominant K+ channel in the apical membrane. Amiloride-sensitive and tertiapin-sensitive whole-cell currents were determined to assess ENaC and ROMK activity, respectively. As expected, baseline amiloride-sensitive current was high in the DCT2/CNT (∼370 pA) but low in the CNT/CCD (∼60 pA). Importantly, tertiapin-sensitive current was significantly higher in the DCT2/CNT than in the CNT/CCD (∼810 vs. ∼350 pA). We conclude that high ROMK activity in the DCT2/CNT is critical for aldosterone-independent renal K+ secretion under baseline conditions. A low-K+ diet significantly reduced ENaC but not ROMK activity in the DCT2/CNT. This suggests that modifying ENaC activity in the DCT2/CNT plays a key regulatory role in adjusting renal K+ excretion to dietary K+ intake.NEW & NOTEWORTHY ROMK-mediated renal K+ secretion is essential for maintaining K+ balance and requires a lumen negative transepithelial potential critically dependent on ENaC activity. Using microdissected distal mouse tubules, we demonstrated that baseline apical ROMK activity is high in the DCT2/CNT. Aldosterone-independent baseline ENaC activity is also high in the DCT2/CNT and downregulated by a low-K+ diet, which highlights the important role of the DCT2/CNT in regulating K+ secretion in an aldosterone-independent manner.
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Affiliation(s)
- Viatcheslav Nesterov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Marko Bertog
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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16
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Ertuglu LA, Elijovich F, Laffer CL, Kirabo A. Salt-Sensitivity of Blood Pressure and Insulin Resistance. Front Physiol 2021; 12:793924. [PMID: 34966295 PMCID: PMC8711096 DOI: 10.3389/fphys.2021.793924] [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: 10/12/2021] [Accepted: 11/18/2021] [Indexed: 12/20/2022] Open
Abstract
Salt sensitivity of blood pressure (SSBP) is an independent risk factor for cardiovascular morbidity and mortality that is seen in both hypertensive and normotensive populations. Insulin resistance (IR) strongly correlates with SSBP and affects nearly 50% of salt sensitive people. While the precise mechanism by which IR and SSBP relate remains elusive, several common pathways are involved in the genesis of both processes, including vascular dysfunction and immune activation. Vascular dysfunction associated with insulin resistance is characterized by loss of nitric oxide (NO)-mediated vasodilation and heightened endothelin-1 induced vasoconstriction, as well as capillary rarefaction. It manifests with increased blood pressure (BP) in salt sensitive murine models. Another common denominator in the pathogenesis of insulin resistance, hypertension, and salt sensitivity (SS) is immune activation involving pro-inflammatory cytokines like tumor necrosis factor (TNF)-α, IL-1β, and IL-6. In the last decade, a new understanding of interstitial sodium storage in tissues such as skin and muscle has revolutionized traditional concepts of body sodium handling and pathogenesis of SS. We have shown that interstitial Na+ can trigger a T cell mediated inflammatory response through formation of isolevuglandin protein adducts in antigen presenting cells (APCs), and that this response is implicated in salt sensitive hypertension. The peroxisome proliferator-activated receptor γ (PPARγ) is a transcription factor that modulates both insulin sensitivity and BP. PPARγ agonists increase insulin sensitivity and ameliorate salt sensitivity, whereas deficiency of PPARγ results in severe insulin resistance and hypertension. These findings suggest that PPARγ plays a role in the common pathogenesis of insulin sensitivity and salt sensitivity, perhaps via effects on the immune system and vascular function. The goal of this review is to discuss those mechanisms that may play a role in both SSBP and in insulin resistance.
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Affiliation(s)
- Lale A Ertuglu
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Fernando Elijovich
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Cheryl L Laffer
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Annet Kirabo
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
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17
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Hiramatsu A, Izumi Y, Eguchi K, Matsuo N, Deng Q, Inoue H, Nakayama Y, Nonoguchi H, Aramburu J, López-Rodríguez C, Kakizoe Y, Adachi M, Kuwabara T, Kim-Mitsuyama S, Mukoyama M. Salt-Sensitive Hypertension of the Renal Tubular Cell-Specific NFAT5 (Nuclear Factor of Activated T-Cells 5) Knockout Mice. Hypertension 2021; 78:1335-1346. [PMID: 34601973 DOI: 10.1161/hypertensionaha.121.17435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Akiko Hiramatsu
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Yuichiro Izumi
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Koji Eguchi
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Naomi Matsuo
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Qinyuan Deng
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Hideki Inoue
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Yushi Nakayama
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Hiroshi Nonoguchi
- Division of Internal Medicine, Kitasato University Medical Center, Kitamoto, Saitama, Japan (H.N.)
| | - Jose Aramburu
- Immunology Unit, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, and Barcelona Biomedical Research Park, Spain (J.A., C.L.-R.)
| | - Cristina López-Rodríguez
- Immunology Unit, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, and Barcelona Biomedical Research Park, Spain (J.A., C.L.-R.)
| | - Yutaka Kakizoe
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Masataka Adachi
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Takashige Kuwabara
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Shokei Kim-Mitsuyama
- Department of Pharmacology and Molecular Therapeutics (S.K.-M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Masashi Mukoyama
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
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18
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Mansley MK, Niklas C, Nacken R, Mandery K, Glaeser H, Fromm MF, Korbmacher C, Bertog M. Prostaglandin E2 stimulates the epithelial sodium channel (ENaC) in cultured mouse cortical collecting duct cells in an autocrine manner. J Gen Physiol 2021; 152:151804. [PMID: 32442241 PMCID: PMC7398144 DOI: 10.1085/jgp.201912525] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Revised: 03/30/2020] [Accepted: 04/21/2020] [Indexed: 12/26/2022] Open
Abstract
Prostaglandin E2 (PGE2) is the most abundant prostanoid in the kidney, affecting a wide range of renal functions. Conflicting data have been reported regarding the effects of PGE2 on tubular water and ion transport. The amiloride-sensitive epithelial sodium channel (ENaC) is rate limiting for transepithelial sodium transport in the aldosterone-sensitive distal nephron. The aim of the present study was to explore a potential role of PGE2 in regulating ENaC in cortical collecting duct (CCD) cells. Short-circuit current (ISC) measurements were performed using the murine mCCDcl1 cell line known to express characteristic properties of CCD principal cells and to be responsive to physiological concentrations of aldosterone and vasopressin. PGE2 stimulated amiloride-sensitive ISC via basolateral prostaglandin E receptors type 4 (EP4) with an EC50 of ∼7.1 nM. The rapid stimulatory effect of PGE2 on ISC resembled that of vasopressin. A maximum response was reached within minutes, coinciding with an increased abundance of β-ENaC at the apical plasma membrane and elevated cytosolic cAMP levels. The effects of PGE2 and vasopressin were nonadditive, indicating similar signaling cascades. Exposing mCCDcl1 cells to aldosterone caused a much slower (∼2 h) increase of the amiloride-sensitive ISC. Interestingly, the rapid effect of PGE2 was preserved even after aldosterone stimulation. Furthermore, application of arachidonic acid also increased the amiloride-sensitive ISC involving basolateral EP4 receptors. Exposure to arachidonic acid resulted in elevated PGE2 in the basolateral medium in a cyclooxygenase 1 (COX-1)–dependent manner. These data suggest that in the cortical collecting duct, locally produced and secreted PGE2 can stimulate ENaC-mediated transepithelial sodium transport.
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Affiliation(s)
- Morag K Mansley
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Christian Niklas
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Regina Nacken
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Kathrin Mandery
- Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Hartmut Glaeser
- Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Martin F Fromm
- Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Christoph Korbmacher
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Marko Bertog
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
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19
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Nesterov V, Bertog M, Canonica J, Hummler E, Coleman R, Welling PA, Korbmacher C. Critical role of the mineralocorticoid receptor in aldosterone-dependent and aldosterone-independent regulation of ENaC in the distal nephron. Am J Physiol Renal Physiol 2021; 321:F257-F268. [PMID: 34251271 PMCID: PMC9847332 DOI: 10.1152/ajprenal.00139.2021] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The epithelial Na+ channel (ENaC) constitutes the rate-limiting step for Na+ absorption in the aldosterone-sensitive distal nephron (ASDN) comprising the late distal convoluted tubule (DCT2), connecting tubule (CNT), and collecting duct (CD). Previously, we demonstrated that ENaC activity in the DCT2/CNT transition zone is constitutively high and independent of aldosterone, in contrast to its aldosterone dependence in the late CNT/initial cortical CD (CCD). The mineralocorticoid receptor (MR) is expressed in the entire ASDN. Its activation by glucocorticoids is prevented through 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2) abundantly expressed in the late but probably not early part of the ASDN. We hypothesized that ENaC function in the early part of the ASDN is aldosterone independent but may depend on MR activated by glucocorticoids due to low 11β-HSD2 abundance. To test this hypothesis, we used doxycycline-inducible nephron-specific MR-deficient [MR knockout (KO)] mice. Whole cell ENaC currents were investigated in isolated nephron fragments from the DCT2/CNT or CNT/CCD transition zones using the patch-clamp technique. ENaC activity was detectable in the CNT/CCD of control mice but absent or barely detectable in the majority of CNT/CCD preparations from MR KO mice. Importantly, ENaC currents in the DCT2/CNT were greatly reduced in MR KO mice compared with ENaC currents in the DCT2/CNT of control mice. Immunofluorescence for 11β-HSD2 was abundant in the CCD, less prominent in the CNT, and very low in the DCT2. We conclude that MR is critically important for maintaining aldosterone-independent ENaC activity in the DCT2/CNT. Aldosterone-independent MR activation is probably mediated by glucocorticoids due to low expression of 11β-HSD2.NEW & NOTEWORTHY Using a mouse model with inducible nephron-specific mineralocorticoid receptor (MR) deficiency, we demonstrated that MR is not only critical for maintaining aldosterone-dependent ENaC activity in CNT/CCD but also for aldosterone-independent ENaC activity in DCT2/CNT. Furthermore, we demonstrated that cells of this latter nephron segment express little 11β-HSD2, which probably allows glucocorticoids to stimulate MR, resulting in aldosterone-independent ENaC activity in DCT2/CNT. This site-specific ENaC regulation has physiologically relevant implications for renal sodium and potassium homeostasis.
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Affiliation(s)
- Viatcheslav Nesterov
- 1Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Marko Bertog
- 1Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jérémie Canonica
- 2Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Edith Hummler
- 2Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Richard Coleman
- 3Departments of Medicine, Nephrology, and Physiology, Johns Hopkins University Medical School, Baltimore, Maryland
| | - Paul A. Welling
- 3Departments of Medicine, Nephrology, and Physiology, Johns Hopkins University Medical School, Baltimore, Maryland
| | - Christoph Korbmacher
- 1Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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20
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Ilyaskin AV, Korbmacher C, Diakov A. Inhibition of the epithelial sodium channel (ENaC) by connexin 30 involves stimulation of clathrin-mediated endocytosis. J Biol Chem 2021; 296:100404. [PMID: 33577799 PMCID: PMC7973139 DOI: 10.1016/j.jbc.2021.100404] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/05/2021] [Accepted: 02/08/2021] [Indexed: 01/16/2023] Open
Abstract
Mice lacking connexin 30 (Cx30) display increased epithelial sodium channel (ENaC) activity in the distal nephron and develop salt-sensitive hypertension. This indicates a functional link between Cx30 and ENaC, which remains incompletely understood. Here, we explore the effect of Cx30 on ENaC function using the Xenopus laevis oocyte expression system. Coexpression of human Cx30 with human αβγENaC significantly reduced ENaC-mediated whole-cell currents. The size of the inhibitory effect on ENaC depended on the expression level of Cx30 and required Cx30 ion channel activity. ENaC inhibition by Cx30 was mainly due to reduced cell surface ENaC expression resulting from enhanced ENaC retrieval without discernible effects on proteolytic channel activation and single-channel properties. ENaC retrieval from the cell surface involves the interaction of the ubiquitin ligase Nedd4-2 with PPPxY-motifs in the C-termini of ENaC. Truncating the C- termini of β- or γENaC significantly reduced the inhibitory effect of Cx30 on ENaC. In contrast, mutating the prolines belonging to the PPPxY-motif in γENaC or coexpressing a dominant-negative Xenopus Nedd4 (xNedd4-CS) did not significantly alter ENaC inhibition by Cx30. Importantly, the inhibitory effect of Cx30 on ENaC was significantly reduced by Pitstop-2, an inhibitor of clathrin-mediated endocytosis, or by mutating putative clathrin adaptor protein 2 (AP-2) recognition motifs (YxxФ) in the C termini of β- or γ-ENaC. In conclusion, our findings suggest that Cx30 inhibits ENaC by promoting channel retrieval from the plasma membrane via clathrin-dependent endocytosis. Lack of this inhibition may contribute to increased ENaC activity and salt-sensitive hypertension in mice with Cx30 deficiency.
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Affiliation(s)
- Alexandr V Ilyaskin
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
| | - Alexei Diakov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
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21
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Ayuzawa N, Fujita T. The Mineralocorticoid Receptor in Salt-Sensitive Hypertension and Renal Injury. J Am Soc Nephrol 2021; 32:279-289. [PMID: 33397690 PMCID: PMC8054893 DOI: 10.1681/asn.2020071041] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Hypertension and its comorbidities pose a major public health problem associated with disease-associated factors related to a modern lifestyle, such high salt intake or obesity. Accumulating evidence has demonstrated that aldosterone and its receptor, the mineralocorticoid receptor (MR), have crucial roles in the development of salt-sensitive hypertension and coexisting cardiovascular and renal injuries. Accordingly, clinical trials have repetitively shown the promising effects of MR blockers in these diseases. We and other researchers have identified novel mechanisms of MR activation involved in salt-sensitive hypertension and renal injury, including the obesity-derived overproduction of aldosterone and ligand-independent signaling. Moreover, recent advances in the analysis of cell-specific and context-dependent mechanisms of MR activation in various tissues-including a classic target of aldosterone, aldosterone-sensitive distal nephrons-are now providing new insights. In this review, we summarize recent updates to our understanding of aldosterone-MR signaling, focusing on its role in salt-sensitive hypertension and renal injury.
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Affiliation(s)
- Nobuhiro Ayuzawa
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Toshiro Fujita
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan,Shinshu University School of Medicine, Nagano, Japan,Research Center for Social Systems, Shinshu University, Nagano, Japan
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22
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Nakamura M, Satoh N, Tsukada H, Mizuno T, Fujii W, Suzuki A, Horita S, Nangaku M, Suzuki M. Stimulatory effect of insulin on H+-ATPase in the proximal tubule via the Akt/mTORC2 pathway. Physiol Int 2020; 107:376-389. [PMID: 32990653 DOI: 10.1556/2060.2020.00030] [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] [Received: 08/18/2019] [Accepted: 06/12/2020] [Indexed: 11/19/2022]
Abstract
Purpose Acid-base transport in renal proximal tubules (PTs) is mainly sodium-dependent and conducted in coordination by the apical Na+/H+ exchanger (NHE3), vacuolar H+-adenosine triphosphatase (V-ATPase), and the basolateral Na+/HCO3- cotransporter. V-ATPase on PTs is well-known to play an important role in proton excretion. Recently we reported a stimulatory effect of insulin on these transporters. However, it is unclear whether insulin is involved in acid-base balance in PTs. Thus, we assessed the role of insulin in acid-base balance in PTs. Methods V-ATPase activity was evaluated using freshly isolated PTs obtained from mice, and specific inhibitors were then used to assess the signaling pathways involved in the observed effects. Results V-ATPase activity in PTs was markedly enhanced by insulin, and its activation was completely inhibited by bafilomycin (a V-ATPase-specific inhibitor), Akt inhibitor VIII, and PP242 (an mTORC1/2 inhibitor), but not by rapamycin (an mTORC1 inhibitor). V-ATPase activity was stimulated by 1 nm insulin by approximately 20% above baseline, which was completely suppressed by Akt1/2 inhibitor VIII. PP242 completely suppressed the insulin-mediated V-ATPase stimulation in mouse PTs, whereas rapamycin failed to influence the effect of insulin. Insulin-induced Akt phosphorylation in the mouse renal cortex was completely suppressed by Akt1/2 inhibitor VIII and PP242, but not by rapamycin. Conclusion Our results indicate that stimulation of V-ATPase activity by insulin in PTs is mediated via the Akt2/mTORC2 pathway. These results reveal the mechanism underlying the complex signaling in PT acid-base balance, providing treatment targets for renal disease.
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Affiliation(s)
- M Nakamura
- 1Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - N Satoh
- 1Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - H Tsukada
- 1Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - T Mizuno
- 1Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - W Fujii
- 1Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - A Suzuki
- 1Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan.,2Department of Nephrology, Japan Community Health care Organization (JCHO), Tokyo Yamate Medical Center, Tokyo, Japan
| | - S Horita
- 1Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - M Nangaku
- 1Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - M Suzuki
- 3Health Service Center, Tokyo Gakugei University, Tokyo, Japan
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23
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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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24
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Jobin K, Stumpf NE, Schwab S, Eichler M, Neubert P, Rauh M, Adamowski M, Babyak O, Hinze D, Sivalingam S, Weisheit C, Hochheiser K, Schmidt SV, Meissner M, Garbi N, Abdullah Z, Wenzel U, Hölzel M, Jantsch J, Kurts C. A high-salt diet compromises antibacterial neutrophil responses through hormonal perturbation. Sci Transl Med 2020; 12:12/536/eaay3850. [DOI: 10.1126/scitranslmed.aay3850] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 02/12/2020] [Indexed: 12/11/2022]
Abstract
The Western diet is rich in salt, which poses various health risks. A high-salt diet (HSD) can stimulate immunity through the nuclear factor of activated T cells 5 (Nfat5)–signaling pathway, especially in the skin, where sodium is stored. The kidney medulla also accumulates sodium to build an osmotic gradient for water conservation. Here, we studied the effect of an HSD on the immune defense against uropathogenic E. coli–induced pyelonephritis, the most common kidney infection. Unexpectedly, pyelonephritis was aggravated in mice on an HSD by two mechanisms. First, on an HSD, sodium must be excreted; therefore, the kidney used urea instead to build the osmotic gradient. However, in contrast to sodium, urea suppressed the antibacterial functionality of neutrophils, the principal immune effectors against pyelonephritis. Second, the body excretes sodium by lowering mineralocorticoid production via suppressing aldosterone synthase. This caused an accumulation of aldosterone precursors with glucocorticoid functionality, which abolished the diurnal adrenocorticotropic hormone–driven glucocorticoid rhythm and compromised neutrophil development and antibacterial functionality systemically. Consistently, under an HSD, systemic Listeria monocytogenes infection was also aggravated in a glucocorticoid-dependent manner. Glucocorticoids directly induced Nfat5 expression, but pharmacological normalization of renal Nfat5 expression failed to restore the antibacterial defense. Last, healthy humans consuming an HSD for 1 week showed hyperglucocorticoidism and impaired antibacterial neutrophil function. In summary, an HSD suppresses intrarenal neutrophils Nfat5-independently by altering the local microenvironment and systemically by glucocorticoid-mediated immunosuppression. These findings argue against high-salt consumption during bacterial infections.
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Affiliation(s)
- Katarzyna Jobin
- Institute of Experimental Immunology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
- Institute for Systems Immunology, Julius Maximilian University of Würzburg, Würzburg, Germany
| | - Natascha E. Stumpf
- Institute of Experimental Immunology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
| | - Sebastian Schwab
- Institute of Experimental Immunology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
- Medizinische Klinik I, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
| | - Melanie Eichler
- Institute of Experimental Immunology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
| | - Patrick Neubert
- Institute of Clinical Microbiology and Hygiene, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Manfred Rauh
- Department of Pediatrics and Adolescent Medicine, University Hospital Erlangen, Loschgestraβe 15, 91054 Erlangen, Germany
| | - Marek Adamowski
- Institute of Experimental Immunology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
| | - Olena Babyak
- Institute of Experimental Immunology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
| | - Daniel Hinze
- Institute of Experimental Oncology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, Bonn, Germany
| | - Sugirthan Sivalingam
- Institute of Experimental Oncology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, Bonn, Germany
| | - Christina Weisheit
- Institute of Experimental Immunology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
- Department of Anesthesiology and Intensive Care Medicine, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
| | - Katharina Hochheiser
- Institute of Experimental Immunology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
| | - Susanne V. Schmidt
- Institute of Innate Immunity, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
| | - Mirjam Meissner
- Institute of Experimental Immunology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
| | - Natalio Garbi
- Institute of Experimental Immunology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
| | - Zeinab Abdullah
- Institute of Experimental Immunology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
| | - Ulrich Wenzel
- Department of Medicine, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Michael Hölzel
- Institute of Experimental Oncology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, Bonn, Germany
| | - Jonathan Jantsch
- Institute of Clinical Microbiology and Hygiene, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
| | - Christian Kurts
- Institute of Experimental Immunology, University Hospital of Bonn, Rheinische Friedrich Wilhelm University, 53127 Bonn, Germany
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC 3010, Australia
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25
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Frindt G, Bertog M, Korbmacher C, Palmer LG. Ubiquitination of renal ENaC subunits in vivo. Am J Physiol Renal Physiol 2020; 318:F1113-F1121. [PMID: 32174140 DOI: 10.1152/ajprenal.00609.2019] [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] [Indexed: 11/22/2022] Open
Abstract
Ubiquitination of the epithelial Na+ channel (ENaC) in epithelial cells may influence trafficking and hormonal regulation of the channels. We assessed ENaC ubiquitination (ub-ENaC) in mouse and rat kidneys using affinity beads to capture ubiquitinated proteins from tissue homogenates and Western blot analysis with anti-ENaC antibodies. Ub-αENaC was observed primarily as a series of proteins of apparent molecular mass of 40-70 kDa, consistent with the addition of variable numbers of ubiquitin molecules primarily to the NH2-terminal cleaved fragment (~30 kDa) of the subunit. No significant Ub-βENaC was detected, indicating that ubiquitination of this subunit is minimal. For γENaC, the protein eluted from the affinity beads had the same apparent molecular mass as the cleaved COOH-terminal fragment of the subunit (~65 kDa). This suggests that the ubiquitinated NH2 terminus remains attached to the COOH-terminal moiety during isolation through disulfide bonds. Consistent with this, under nonreducing conditions, eluates contained material with increased molecular mass (90-150 kDa). In mice with a Liddle syndrome mutation (β566X) deleting a putative binding site for the ubiquitin ligase neural precursor cell expressed developmentally downregulated 4-2, the amount of ub-γENaC was reduced as expected. To assess aldosterone dependence of ubiquitination, we fed rats either control or low-Na+ diets for 7 days before kidney harvest. Na+ depletion increased the amounts of ub-αENaC and ub-γENaC by three- to fivefold, probably reflecting increased amounts of fully cleaved ENaC. We conclude that ubiquitination occurs after complete proteolytic processing of the subunits, contributing to retrieval and/or disposal of channels expressed at the cell surface. Diminished ubiquitination does not appear to be a major factor in aldosterone-dependent ENaC upregulation.
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Affiliation(s)
- Gustavo Frindt
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, New York
| | - Marko Bertog
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Lawrence G Palmer
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, New York
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26
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Mansley MK, Roe AJ, Francis SL, Gill JH, Bailey MA, Wilson SM. Trichostatin A blocks aldosterone-induced Na + transport and control of serum- and glucocorticoid-inducible kinase 1 in cortical collecting duct cells. Br J Pharmacol 2019; 176:4708-4719. [PMID: 31423568 DOI: 10.1111/bph.14837] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 06/30/2019] [Accepted: 07/26/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND AND PURPOSE Aldosterone stimulates epithelial Na+ channel (ENaC)-dependent Na+ retention in the cortical collecting duct (CCD) of the kidney by activating mineralocorticoid receptors that promote expression of serum and glucocorticoid-inducible kinase 1 (SGK1). This response is critical to BP homeostasis. It has previously been suggested that inhibiting lysine deacetylases (KDACs) can post-transcriptionally disrupt this response by promoting acetylation of the mineralocorticoid receptor. The present study critically evaluates this hypothesis. EXPERIMENTAL APPROACH Electrometric and molecular methods were used to define the effects of a pan-KDAC inhibitor, trichostatin A, on the responses to a physiologically relevant concentration of aldosterone (3 nM) in murine mCCDcl1 cells. KEY RESULTS Aldosterone augmented ENaC-induced Na+ absorption and increased SGK1 activity and abundance, as expected. In the presence of trichostatin A, these responses were suppressed. Trichostatin A-induced inhibition of KDAC was confirmed by increased acetylation of histone H3, H4, and α-tubulin. Trichostatin A did not block the electrometric response to insulin, a hormone that activates SGK1 independently of increased transcription, indicating that trichostatin A has no direct effect upon the SGK1/ENaC pathway. CONCLUSIONS AND IMPLICATIONS Inhibition of lysine de-acetylation suppresses aldosterone-dependent control over the SGK1-ENaC pathway but does not perturb post-transcriptional signalling, providing a physiological basis for the anti-hypertensive action of KDAC inhibition seen in vivo.
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Affiliation(s)
- Morag K Mansley
- Division of Pharmacy, School of Medicine, Pharmacy and Health, Durham University Queen's Campus, Stockton-on-Tees, UK.,Centre for Cardiovascular Science, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | - Andrew J Roe
- Division of Pharmacy, School of Medicine, Pharmacy and Health, Durham University Queen's Campus, Stockton-on-Tees, UK
| | - Sarah L Francis
- Division of Pharmacy, School of Medicine, Pharmacy and Health, Durham University Queen's Campus, Stockton-on-Tees, UK
| | - Jason H Gill
- Division of Pharmacy, School of Medicine, Pharmacy and Health, Durham University Queen's Campus, Stockton-on-Tees, UK
| | - Matthew A Bailey
- Centre for Cardiovascular Science, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | - Stuart M Wilson
- Division of Pharmacy, School of Medicine, Pharmacy and Health, Durham University Queen's Campus, Stockton-on-Tees, UK
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27
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Kelley EF, Olson TP, Curry TB, Sprissler R, Snyder EM. The Effect of Genetically Guided Mathematical Prediction and the Blood Pressure Response to Pharmacotherapy in Hypertension Patients. Clin Med Insights Cardiol 2019; 13:1179546819845883. [PMID: 31105432 PMCID: PMC6501483 DOI: 10.1177/1179546819845883] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 04/03/2019] [Indexed: 01/13/2023] Open
Abstract
Purpose: The purpose of this study was to determine the effectiveness of a simple algorithm to mathematically predict a patients’ response to blood pressure (BP) therapy using functional genes in the 3 major organ systems involved in hypertension. Methods: Eighty-six patients with controlled hypertension completed 1 study visit consisting of a buccal swab collection, measurement of office BP, and a medical chart review for BP history. Genes in the analysis included 14 functional alleles in 11 genes. These genotypes were mathematically summed per organ system to determine whether a patient would likely respond to target therapy. Results: Patients recommended to and taking a diuretic had significantly higher rates of control (<120/<80) than patients recommended but not taking this drug class (0.2 ± 0.1 and 0.03 ± 0.03, respectively). Furthermore, there was a difference between patients genetically recommended and taking an angiotensin receptor blocker (ARB) vs patients recommended but not taking an ARB for the lowest diastolic blood pressure (DBP) and mean arterial pressure (MAP) recorded in the past 2 years (DBP = 66.2 ± 2.9 and 75.3 ± 1.7, MAP = 82.3 ± 2.8 and 89.3 ± 1.5, respectively). In addition, there was a nonsignificant trend for greater reductions in ΔSBP, ΔDBP, and ΔMAP in patients on recommended drug class for beta-blockers, diuretics, and angiotensin II receptor blockers vs patients not on these classes. Conclusion: The present study suggests that simple mathematical weighting of functional genotypes known to control BP may be ineffective in predicting control. This study demonstrates the need for a more complex, weighted, multigene algorithm to more accurately predict BP therapy response.
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Affiliation(s)
- Eli F Kelley
- School of Kinesiology, University of Minnesota, Minneapolis, MN, USA
| | - Thomas P Olson
- Geneticure, Inc, Rochester, MN, USA.,College of Medicine and Science, Mayo Clinic, Rochester, MN, USA
| | - Timothy B Curry
- Geneticure, Inc, Rochester, MN, USA.,College of Medicine and Science, Mayo Clinic, Rochester, MN, USA
| | - Ryan Sprissler
- Geneticure, Inc, Rochester, MN, USA.,Department of Genetics, University of Arizona Genomics Core, Tucson, AZ, USA
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Liu GZ, Zhang S, Li YY, Liu YW, Zhang Y, Zhao XB, Yuan Y, Zhang JW, Khannanova Z, Li Y. Aldosterone stimulation mediates cardiac metabolism remodeling via Sirt1/AMPK signaling in canine model. Naunyn Schmiedebergs Arch Pharmacol 2019; 392:851-863. [PMID: 30852656 DOI: 10.1007/s00210-019-01641-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Accepted: 02/28/2019] [Indexed: 11/29/2022]
Abstract
Aldosterone (Aldo), a pivotal hormone that is ubiquitously expressed in systemic tissues of mammals, is a crucial factor in the pathogenesis of cardiac disease. Accumulating evidence suggests that disturbances in cell energy metabolism are involved in increasing aldosterone levels. However, the precise mechanism underlying the impact of cardiac metabolic remodeling underlying aldosterone stimulation remains limited. In this work, we evaluated the underlying effect of aldosterone on regulating cardiac metabolism remodeling in a canine model. Fifteen beagle dogs were divided into a control group (n = 5), Aldo group (n = 5), and a group treated with spironolactone (SP), a mineralocorticoid receptor antagonist (n = 5), for 4 weeks. Blood pressure, electrocardiogram and respiratory parameters, H&E, Masson staining, ultrastructural changes, the adenosine triphosphate (ATP) and free fatty acid (FFA) levels of ventricular tissues, the level of mRNA, and the protein expression of key metabolic factors and regulators were assessed. The Sirt1/AMPK signaling pathway was significantly inhibited in the canine model of aldosterone stimulation, resulting in a reduction of the key downstream metabolic factors involved in glucose and fatty acid oxidation. The dysregulation of expression of key factors in glycogen metabolism led to glycogen deposition, an increase in FFA levels, a reduction in ATP levels, apoptosis, inflammatory cell infiltration, and mitochondrial damage in the ventricular myocardium. These effects were significantly restored by spironolactone. Aldosterone stimulation induced cardiac metabolic remodeling in ventricular cardiomyocytes possibly through the Sirt1/AMPK signaling pathway, implying that this pathway may provide a novel therapeutic target for cardiac metabolic remodeling.
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Affiliation(s)
- Guang-Zhong Liu
- Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, Youzheng Street 23#, Nangang District, Harbin, 150001, Heilongjiang Province, China
| | - Song Zhang
- Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, Youzheng Street 23#, Nangang District, Harbin, 150001, Heilongjiang Province, China
| | - Yan-Yan Li
- Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, Youzheng Street 23#, Nangang District, Harbin, 150001, Heilongjiang Province, China
| | - Yong-Wu Liu
- Centre for Drug Safety Evaluation, Heilongjiang University of Chinese Medicine, Harbin, 150001, Heilongjiang Province, China
| | - Yun Zhang
- Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, Youzheng Street 23#, Nangang District, Harbin, 150001, Heilongjiang Province, China
| | - Xin-Bo Zhao
- Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, Youzheng Street 23#, Nangang District, Harbin, 150001, Heilongjiang Province, China
| | - Yue Yuan
- Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, Youzheng Street 23#, Nangang District, Harbin, 150001, Heilongjiang Province, China
| | - Jia-Wei Zhang
- Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, Youzheng Street 23#, Nangang District, Harbin, 150001, Heilongjiang Province, China
| | - Zulfiia Khannanova
- Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, Youzheng Street 23#, Nangang District, Harbin, 150001, Heilongjiang Province, China
| | - Yue Li
- Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, Youzheng Street 23#, Nangang District, Harbin, 150001, Heilongjiang Province, China. .,Key Laboratory of Cardiac Diseases and Heart Failure, Harbin Medical University, Harbin, 150001, Heilongjiang Province, China. .,Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Harbin, 150001, Heilongjiang Province, China.
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Phelps PK, Kelley EF, Walla DM, Ross JK, Simmons JJ, Bulock EK, Ayres A, Akre MK, Sprissler R, Olson TP, Snyder EM. Relationship between a Weighted Multi-Gene Algorithm and Blood Pressure Control in Hypertension. J Clin Med 2019; 8:jcm8030289. [PMID: 30823438 PMCID: PMC6463118 DOI: 10.3390/jcm8030289] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 02/16/2019] [Accepted: 02/25/2019] [Indexed: 01/01/2023] Open
Abstract
Hypertension (HTN) is a complex disease with interactions among multiple organ systems, including the heart, vasculature, and kidney with a strong heritable component. Despite the multifactorial nature of HTN, no clinical guidelines utilize a multi-gene approach to guide blood pressure (BP) therapy. Non-smokers with a family history of HTN were included in the analysis (n = 384; age = 61.0 ± 0.9, 11% non-white). A total of 17 functional genotypes were weighted according to the previous effect size in the literature and entered into an algorithm. Pharmacotherapy was ranked from 1–4 as most to least likely to respond based on the algorithmic assessment of individual patient’s genotypes. Three-years of data were assessed at six-month intervals for BP and medication history. There was no difference in BP at diagnosis between groups matching the top drug recommendation using the multi-gene weighted algorithm (n = 92) vs. those who did not match (n = 292). However, from diagnosis to nadir, patients who matched the primary recommendation had a significantly greater drop in BP when compared to patients who did not. Further, the difference between diagnosis to current 1-year average BP was lower in the group that matched the top recommendation. These data suggest an association between a weighted multi-gene algorithm on the BP response to pharmacotherapy.
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Affiliation(s)
- Pamela K Phelps
- Medical Center, University of Minnesota, Fairview, Minneapolis, MN 55455, USA.
| | - Eli F Kelley
- School of Kinesiology, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Danielle M Walla
- Medical Center, University of Minnesota, Fairview, Minneapolis, MN 55455, USA.
| | - Jennifer K Ross
- Medical Center, University of Minnesota, Fairview, Minneapolis, MN 55455, USA.
| | - Jerad J Simmons
- Medical Center, University of Minnesota, Fairview, Minneapolis, MN 55455, USA.
| | - Emma K Bulock
- Medical Center, University of Minnesota, Fairview, Minneapolis, MN 55455, USA.
| | - Audrie Ayres
- Medical Center, University of Minnesota, Fairview, Minneapolis, MN 55455, USA.
| | | | - Ryan Sprissler
- Geneticure, Inc., Rochester, MN 55902, USA.
- University of Arizona Genomics Core, University of Arizona, Tucson, AZ 85705, USA.
| | - Thomas P Olson
- Geneticure, Inc., Rochester, MN 55902, USA.
- College of Medicine, Mayo Clinic, Rochester, MN 55905, USA.
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Romero CA, Carretero OA. A Novel Mechanism of Renal Microcirculation Regulation: Connecting Tubule-Glomerular Feedback. Curr Hypertens Rep 2019; 21:8. [PMID: 30659366 DOI: 10.1007/s11906-019-0911-5] [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] [Indexed: 12/15/2022]
Abstract
PURPOSE OF REVIEW In this review, we summarized the current knowledge of connecting tubule-glomerular feedback (CTGF), a novel mechanism of renal microcirculation regulation that integrates sodium handling in the connecting tubule (CNT) with kidney hemodynamics. RECENT FINDINGS Connecting tubule-glomerular feedback is a crosstalk communication between the CNT and the afferent arteriole (Af-Art), initiated by sodium chloride through the epithelial sodium channel (ENaC). High sodium in the CNT induces Af-Art vasodilation, increasing glomerular pressure and the glomerular filtration rate and favoring sodium excretion. CTGF antagonized and reset tubuloglomerular feedback and thus increased sodium excretion. CTGF is absent in spontaneous hypertensive rats and is overactivated in Dahl salt-sensitive rats. CTGF is also modulated by angiotensin II and aldosterone. CTGF is a feedback mechanism that integrates sodium handling in the CNT with glomerular hemodynamics. Lack of CTGF could promote hypertension, and CTGF overactivation may favor glomerular damage and proteinuria. More studies are needed to explore the alterations in renal microcirculation and the role of these alterations in the genesis of hypertension and glomerular damage in animals and humans. KEY POINTS • CTGF is a vasodilator mechanism that regulates afferent arteriole resistance. • CTGF is absent in spontaneous hypertensive rats and overactivated in Dahl salt-sensitive rats. • CTGF in excess may promote glomerular damage and proteinuria, while the absence may participate in sodium retention and hypertension.
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Affiliation(s)
- Cesar A Romero
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 2799 West Grand Boulevard, Detroit, MI, 48202-2689, USA.
| | - Oscar A Carretero
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 2799 West Grand Boulevard, Detroit, MI, 48202-2689, USA
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Zhang P, Gu L, Cong J, Zhang J, Thomsen JS, Andreasen A, Chang SJ, Deng SQ, Xing J, Zhai XY. Morphology of the initial nephron-collecting duct connection in mice using computerized 3D tracing and electron microscopy. Biochem Biophys Res Commun 2019; 509:114-118. [DOI: 10.1016/j.bbrc.2018.12.079] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Accepted: 12/11/2018] [Indexed: 11/16/2022]
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Rossitto G, Cesari M, Ceolotto G, Maiolino G, Seccia TM, Rossi GP. Effects of mineralocorticoid and AT-1 receptor antagonism on the aldosterone–renin ratio (ARR) in primary aldosteronism patients (EMIRA Study): rationale and design. J Hum Hypertens 2018; 33:167-171. [DOI: 10.1038/s41371-018-0139-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 10/29/2018] [Accepted: 11/15/2018] [Indexed: 11/09/2022]
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Al-Fifi ZI, Mujallid MI. Effect of circadian on the activities of ion transport ATPases and histological structure of kidneys in mice. Saudi J Biol Sci 2018; 26:963-969. [PMID: 31303826 PMCID: PMC6601028 DOI: 10.1016/j.sjbs.2018.06.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 06/17/2018] [Accepted: 06/27/2018] [Indexed: 02/07/2023] Open
Abstract
The impacts of unnatural every day cycles (circadian) for 60 days on the histological structure of kidneys and ATPase activities in MF1 mice were studied. The exposure times were 16 h dark, 16 h light, 24 h dark, and 24 h light, and control exposure times were 12 h dark followed by 12 h light. Our results showed an increase in the total ATPase activity of mice in all groups. Additionally, the activity of the enzyme Na+/K+-ATPase was increased after 24 h darkness, 24 h light, and 16 h light exposures compared to control. The enzyme Mg+2-ATPase activities of the groups were higher when exposed to 16 h light, 24 h light, 24 h darkness and 16 h darkness. The activities of total ATPase, Na+/K+-ATPase and Mg+2-ATPase in kidneys were increased in all groups after 24 h light, 24 h darkness, 16 h darkness and 16 h light exposures. Interestingly, the activity of V-type ATPase was reduced after 16 h darkness, 24 h darkness and 16 h light. Taking everything into account, changes in the day by day cycle prompt neurotic changes, enzymatic and histological changes in the kidneys of mice. More studies should be directed to explore the impacts of light and darkness that can prompt these progressions.
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Affiliation(s)
- Zarraq I Al-Fifi
- Department of Biology, Faculty of Science, Jazan University, Saudi Arabia
| | - Mohammad I Mujallid
- Department of Biology, Faculty of Science, King Abdulaziz University, Saudi Arabia
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Harvey BJ, Thomas W. Aldosterone-induced protein kinase signalling and the control of electrolyte balance. Steroids 2018; 133:67-74. [PMID: 29079406 DOI: 10.1016/j.steroids.2017.10.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 10/18/2017] [Accepted: 10/21/2017] [Indexed: 01/20/2023]
Abstract
Aldosterone acts through the mineralocorticoid receptor (MR) to modulate gene expression in target tissues. In the kidney, the principal action of aldosterone is to promote sodium conservation in the distal nephron and so indirectly enhance water conservation under conditions of hypotension. Over the last twenty years the rapid activation of protein kinase signalling cascades by aldosterone has been described in various tissues. This review describes the integration of rapid protein kinase D signalling responses with the non-genomic actions of aldosterone and transcriptional effects of MR activation.
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Affiliation(s)
- Brian J Harvey
- Molecular Medicine Laboratories, Royal College of Surgeons in Ireland, Education Centre, Beaumont Hospital, Dublin, Ireland
| | - Warren Thomas
- Molecular Medicine Laboratories, Royal College of Surgeons in Ireland, Education Centre, Beaumont Hospital, Dublin, Ireland; Perdana University - Royal College of Surgeons in Ireland School of Medicine, Serdang, Selangor, Malaysia.
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Abstract
The kidneys regulate many vital functions that require precise control throughout the day. These functions, such as maintaining sodium balance or regulating arterial pressure, rely on an intrinsic clock mechanism that was commonly believed to be controlled by the central nervous system. Mounting evidence in recent years has unveiled previously underappreciated depth of influence by circadian rhythms and clock genes on renal function, at the molecular and physiological level, independent of other external factors. The impact of circadian rhythms in the kidney also affects individuals from a clinical standpoint, as the loss of rhythmic activity or clock gene expression have been documented in various cardiovascular diseases. Fortunately, the prognostic value of examining circadian rhythms may prove useful in determining the progression of a kidney-related disease, and chronotherapy is a clinical intervention that requires consideration of circadian and diurnal rhythms in the kidney. In this review, we discuss evidence of circadian regulation in the kidney from basic and clinical research in order to provide a foundation on which a great deal of future research is needed to expand our understanding of circadian relevant biology.
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Affiliation(s)
- Jermaine G Johnston
- Section of Cardio-Renal Physiology and Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - David M Pollock
- Section of Cardio-Renal Physiology and Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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The phosphorylation site T613 in the β-subunit of rat epithelial Na+ channel (ENaC) modulates channel inhibition by Nedd4-2. Pflugers Arch 2018; 470:649-660. [DOI: 10.1007/s00424-018-2115-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 01/17/2018] [Accepted: 01/23/2018] [Indexed: 10/18/2022]
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Whole Transcriptome Sequencing Analyses Reveal Molecular Markers of Blood Pressure Response to Thiazide Diuretics. Sci Rep 2017; 7:16068. [PMID: 29167564 PMCID: PMC5700078 DOI: 10.1038/s41598-017-16343-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 11/10/2017] [Indexed: 01/13/2023] Open
Abstract
Thiazide diuretics (TD) are commonly prescribed anti-hypertensives worldwide. However, <40% of patients treated with thiazide monotherapy achieve BP control. This study uses whole transcriptome sequencing to identify novel molecular markers associated with BP response to TD. We assessed global RNA expression levels in whole blood samples from 150 participants, representing patients in the upper and lower quartile of BP response to TD from the Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR) (50 whites) and from PEAR-2 (50 whites and 50 blacks). In each study cohort, we performed poly-A RNA-sequencing in baseline samples from 25 responders and 25 non-responders to hydrochlorothiazide (HCTZ) or chlorthalidone. At FDR adjusted p-value < 0.05, 29 genes were differentially expressed in relation to HCTZ or chlorthalidone BP response in whites. For each differentially expressed gene, replication was attempted in the alternate white group and PEAR-2 blacks. CEBPD (meta-analysis p = 1.8 × 10−11) and TSC22D3 (p = 1.9 × 10−9) were differentially expressed in all 3 cohorts, and explain, in aggregate, 21.9% of response variability to TD. This is the first report of the use of transcriptome-wide sequencing data to identify molecular markers of antihypertensive drug response. These findings support CEBPD and TSC22D3 as potential biomarkers of BP response to TD.
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Poulsen SB, Christensen BM. Long-term aldosterone administration increases renal Na+-Cl− cotransporter abundance in late distal convoluted tubule. Am J Physiol Renal Physiol 2017; 313:F756-F766. [DOI: 10.1152/ajprenal.00352.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 10/04/2016] [Accepted: 10/07/2016] [Indexed: 11/22/2022] Open
Abstract
Renal Na+-Cl− cotransporter (NCC) is expressed in early distal convoluted tubule (DCT) 1 and late DCT (DCT2). NCC activity can be stimulated by aldosterone administration, and the mechanism is assumed to depend on the enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), which inactivates glucocorticoids that would otherwise occupy aldosterone receptors. Because 11β-HSD2 in rat may only be abundantly expressed in DCT2 cells and not in DCT1 cells, it has been speculated that aldosterone specifically stimulates NCC activity in DCT2 cells. In mice, however, it is debated if 11β-HSD2 is expressed in DCT2 cells. The present study examined whether aldosterone administration in mice stimulates NCC abundance and phosphorylation in DCT2 cells but not in DCT1 cells. B6/C57 male mice were administered 100 µg aldosterone·kg body weight−1·24 h−1 for 6 days and euthanized during isoflurane inhalation. Western blotting of whole kidney homogenate showed that aldosterone administration stimulated NCC and pT58-NCC abundances ( P < 0.001). In DCT1 cells, confocal microscopy detected no effect of the aldosterone administration on NCC and pT58-NCC abundances. By contrast, NCC and pT58-NCC abundances were stimulated by aldosterone administration in the middle of DCT2 ( P < 0.001 and <0.01, respectively) and at the junction between DCT2 and CNT ( P < 0.001 and <0.05, respectively). In contrast to rat, immunohistochemistry in mouse showed no/very weak 11β-HSD2 expression in DCT2 cells. Collectively, long-term aldosterone administration stimulates mouse NCC and pT58-NCC abundances in DCT2 cells and presumably not in DCT1 cells.
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Inhibitors of the proteasome stimulate the epithelial sodium channel (ENaC) through SGK1 and mimic the effect of aldosterone. Pflugers Arch 2017; 470:295-304. [DOI: 10.1007/s00424-017-2060-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 08/17/2017] [Accepted: 08/21/2017] [Indexed: 10/19/2022]
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Al Therwani S, Malmberg MES, Rosenbaek JB, Bech JN, Pedersen EB. Effect of tolvaptan on renal handling of water and sodium, GFR and central hemodynamics in autosomal dominant polycystic kidney disease during inhibition of the nitric oxide system: a randomized, placebo-controlled, double blind, crossover study. BMC Nephrol 2017; 18:268. [PMID: 28810844 PMCID: PMC5558668 DOI: 10.1186/s12882-017-0686-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 08/07/2017] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Tolvaptan slows progression of autosomal dominant polycystic kidney disease (ADPKD) by antagonizing the vasopressin-cAMP axis. Nitric oxide (NO) stimulates natriuresis and diuresis, but its role is unknown during tolvaptan treatment in ADPKD. METHODS Eighteen patients with ADPKD received tolvaptan 60 mg or placebo in a randomized, placebo-controlled, double blind, crossover study. L-NMMA (L-NG-monomethyl-arginine) was given as a bolus followed by continuous infusion during 60 min. We measured: GFR, urine output (UO), free water clearance (CH2O), fractional excretion of sodium (FENa), urinary excretion of aquaporin-2 channels (u-AQP2) and epithelial sodium channels (u-ENaCγ), plasma concentrations of vasopressin (p-AVP), renin (PRC), angiotensinII (p-AngII), aldosterone (p-Aldo), and central blood pressure (cBP). RESULTS During tolvaptan with NO-inhibition, a more pronounced decrease was measured in UO, CH2O (61% vs 43%) and FENa (46% vs 41%) after placebo than after tolvaptan; GFR and u-AQP2 decreased to the same extent; p-AVP increased three fold, whereas u-ENaCγ, PRC, p-AngII, and p-Aldo remained unchanged. After NO-inhibition, GFR increased after placebo and remained unchanged after tolvaptan (5% vs -6%). Central diastolic BP (CDBP) increased to a higher level after placebo than tolvaptan. Body weight fell during tolvaptan treatment. CONCLUSIONS During NO inhibition, tolvaptan antagonized both the antidiuretic and the antinatriuretic effect of L-NMMA, partly via an AVP-dependent mechanism. U-AQP2 was not changed by tolvaptan, presumeably due to a counteracting effect of elevated p-AVP. The reduced GFR during tolvaptan most likely is caused by the reduction in extracellular fluid volume and blood pressure. TRIAL REGISTRATION Clinical Trial no: NCT02527863 . Registered 18 February 2015.
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Affiliation(s)
- Safa Al Therwani
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark.
| | - My Emma Sofie Malmberg
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Jeppe Bakkestroem Rosenbaek
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Jesper Noergaard Bech
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Erling Bjerregaard Pedersen
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
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Al Therwani S, Rosenbæk JB, Mose FH, Bech JN, Pedersen EB. Effect of tolvaptan on renal water and sodium excretion and blood pressure during nitric oxide inhibition: a dose-response study in healthy subjects. BMC Nephrol 2017; 18:86. [PMID: 28288570 PMCID: PMC5347830 DOI: 10.1186/s12882-017-0501-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 03/07/2017] [Indexed: 01/17/2023] Open
Abstract
Background Tolvaptan is a selective vasopressin receptor antagonist. Nitric Oxide (NO) promotes renal water and sodium excretion, but the effect is unknown in the nephron’s principal cells. In a dose-response study, we measured the effect of tolvaptan on renal handling of water and sodium and systemic hemodynamics, during baseline and NO-inhibition with L-NMMA (L-NG-monomethyl-arginine). Methods In a randomized, placebo-controlled, double blind, cross over study, 15 healthy subjects received tolvaptan 15, 30 and 45 mg or placebo. L-NMMA was given as a bolus followed by continuous infusion during 60 min. We measured urine output (UO), free water clearance (CH2O), fractional excretion of sodium (FENa), urinary aquaporin-2 channels (u-AQP2) and epithelial sodium channels (u-ENaCγ), plasma vasopressin (p-AVP) and central blood pressure (cBP). Results During baseline, FENa was unchanged. Tolvaptan decreased u-ENaCγ dose-dependently and increased p-AVP threefold, whereas u-AQP2 was unchanged. During tolvaptan with NO-inhibition, UO and CH2O decreased dose-dependently. FENa decreased dose-independently and u-ENaCγ remained unchanged. Central BP increased equally after all treatments. Conclusions During baseline, fractional excretion of sodium was unchanged. During tolvaptan with NO-inhibition, renal water excretion was reduced dose dependently, and renal sodium excretion was reduced unrelated to the dose, partly via an AVP dependent mechanism. Thus, tolvaptan antagonized the reduction in renal water and sodium excretion during NO-inhibition. Most likely, the lack of decrease in AQP2 excretion by tolvaptan could be attributed to a counteracting effect of the high level of p-AVP. Trial registration Clinical Trial no: NCT02078973. Registered 1 March 2014. Electronic supplementary material The online version of this article (doi:10.1186/s12882-017-0501-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Safa Al Therwani
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital, Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark.
| | - Jeppe Bakkestrøm Rosenbæk
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital, Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Frank Holden Mose
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital, Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Jesper Nørgaard Bech
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital, Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Erling Bjerregaard Pedersen
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital, Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
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Ong GSY, Young MJ. Mineralocorticoid regulation of cell function: the role of rapid signalling and gene transcription pathways. J Mol Endocrinol 2017; 58:R33-R57. [PMID: 27821439 DOI: 10.1530/jme-15-0318] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 11/06/2016] [Indexed: 12/22/2022]
Abstract
The mineralocorticoid receptor (MR) and mineralocorticoids regulate epithelial handling of electrolytes, and induces diverse effects on other tissues. Traditionally, the effects of MR were ascribed to ligand-receptor binding and activation of gene transcription. However, the MR also utilises a number of intracellular signalling cascades, often by transactivating unrelated receptors, to change cell function more rapidly. Although aldosterone is the physiological mineralocorticoid, it is not the sole ligand for MR. Tissue-selective and mineralocorticoid-specific effects are conferred through the enzyme 11β-hydroxysteroid dehydrogenase 2, cellular redox status and properties of the MR itself. Furthermore, not all aldosterone effects are mediated via MR, with implication of the involvement of other membrane-bound receptors such as GPER. This review will describe the ligands, receptors and intracellular mechanisms available for mineralocorticoid hormone and receptor signalling and illustrate their complex interactions in physiology and disease.
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Affiliation(s)
- Gregory S Y Ong
- Cardiovascular Endocrinology LaboratoryCentre for Endocrinology and Metabolism, Hudson Institute of Medical Research, Clayton, Victoria, Australia
- Department of MedicineSchool of Clinical Sciences, Monash University, Clayton, Victoria, Australia
| | - Morag J Young
- Cardiovascular Endocrinology LaboratoryCentre for Endocrinology and Metabolism, Hudson Institute of Medical Research, Clayton, Victoria, Australia
- Department of PhysiologySchool of Biomedical Sciences, Monash University, Clayton, Victoria, Australia
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Mansley MK, Watt GB, Francis SL, Walker DJ, Land SC, Bailey MA, Wilson SM. Dexamethasone and insulin activate serum and glucocorticoid-inducible kinase 1 (SGK1) via different molecular mechanisms in cortical collecting duct cells. Physiol Rep 2016; 4:4/10/e12792. [PMID: 27225626 PMCID: PMC4886164 DOI: 10.14814/phy2.12792] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 03/29/2016] [Indexed: 01/12/2023] Open
Abstract
Serum and glucocorticoid-inducible kinase 1 (SGK1) is a protein kinase that contributes to the hormonal control of renal Na(+) retention by regulating the abundance of epithelial Na(+) channels (ENaC) at the apical surface of the principal cells of the cortical collecting duct (CCD). Although glucocorticoids and insulin stimulate Na(+) transport by activating SGK1, the responses follow different time courses suggesting that these hormones act by different mechanisms. We therefore explored the signaling pathways that allow dexamethasone and insulin to stimulate Na(+) transport in mouse CCD cells (mpkCCDcl4). Dexamethasone evoked a progressive augmentation of electrogenic Na(+) transport that became apparent after ~45 min latency and was associated with increases in SGK1 activity and abundance and with increased expression of SGK1 mRNA Although the catalytic activity of SGK1 is maintained by phosphatidylinositol-OH-3-kinase (PI3K), dexamethasone had no effect upon PI3K activity. Insulin also stimulated Na(+) transport but this response occurred with no discernible latency. Moreover, although insulin also activated SGK1, it had no effect upon SGK1 protein or mRNA abundance. Insulin did, however, evoke a clear increase in cellular PI3K activity. Our data are consistent with earlier work, which shows that glucocorticoids regulate Na(+) retention by inducing sgk1 gene expression, and also establish that this occurs independently of increased PI3K activity. Insulin, on the other hand, stimulates Na(+) transport via a mechanism independent of sgk1 gene expression that involves PI3K activation. Although both hormones act via SGK1, our data show that they activate this kinase by distinct physiological mechanisms.
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Affiliation(s)
- Morag K Mansley
- Division of Pharmacy, School of Medicine, Pharmacy and Health, Durham University Queen's Campus, Stockton-on-Tees, UK
| | - Gordon B Watt
- Medical Research Institute, College of Medicine, Dentistry and Nursing, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - Sarah L Francis
- Division of Pharmacy, School of Medicine, Pharmacy and Health, Durham University Queen's Campus, Stockton-on-Tees, UK
| | - David J Walker
- Medical Research Institute, College of Medicine, Dentistry and Nursing, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - Stephen C Land
- Medical Research Institute, College of Medicine, Dentistry and Nursing, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - Matthew A Bailey
- The British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - Stuart M Wilson
- Division of Pharmacy, School of Medicine, Pharmacy and Health, Durham University Queen's Campus, Stockton-on-Tees, UK
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Ilatovskaya DV, Palygin O, Staruschenko A. Functional and therapeutic importance of purinergic signaling in polycystic kidney disease. Am J Physiol Renal Physiol 2016; 311:F1135-F1139. [PMID: 27654892 DOI: 10.1152/ajprenal.00406.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 09/20/2016] [Indexed: 12/12/2022] Open
Abstract
Polycystic kidney diseases (PKD) are a group of inherited nephropathies marked with the formation of fluid-filled cysts along the nephron. This renal disorder affects millions of people worldwide, but current treatment strategies are unfortunately limited to supportive therapy, dietary restrictions, and, eventually, renal transplantation. Recent advances in PKD management are aimed at targeting exaggerated cell proliferation and dedifferentiation to interfere with cyst growth. However, not nearly enough is known about the ion transport properties of the cystic cells, or specific signaling pathways modulating channels and transporters in this condition. There is growing evidence that abnormally elevated concentrations of adenosine triphosphate (ATP) in PKD may contribute to cyst enlargement; change in the profile of purinergic receptors may also result in promotion of cystogenesis. The current mini-review is focused on the role of ATP and associated signaling affecting ion transport properties of the renal cystic epithelia.
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Affiliation(s)
- Daria V Ilatovskaya
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
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Ilyaskin AV, Diakov A, Korbmacher C, Haerteis S. Activation of the Human Epithelial Sodium Channel (ENaC) by Bile Acids Involves the Degenerin Site. J Biol Chem 2016; 291:19835-47. [PMID: 27489102 DOI: 10.1074/jbc.m116.726471] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Indexed: 12/22/2022] Open
Abstract
The epithelial sodium channel (ENaC) is a member of the ENaC/degenerin ion channel family, which also includes the bile acid-sensitive ion channel (BASIC). So far little is known about the effects of bile acids on ENaC function. ENaC is probably a heterotrimer consisting of three well characterized subunits (αβγ). In humans, but not in mice and rats, an additional δ-subunit exists. The aim of this study was to investigate the effects of chenodeoxycholic, cholic, and deoxycholic acid in unconjugated (CDCA, CA, and DCA) and tauro-conjugated (t-CDCA, t-CA, t-DCA) form on human ENaC in its αβγ- and δβγ-configuration. We demonstrated that tauro-conjugated bile acids significantly stimulate ENaC in the αβγ- and in the δβγ-configuration. In contrast, non-conjugated bile acids have a robust stimulatory effect only on δβγENaC. Bile acids stimulate ENaC-mediated currents by increasing the open probability of active channels without recruiting additional near-silent channels known to be activated by proteases. Stimulation of ENaC activity by bile acids is accompanied by a significant reduction of the single-channel current amplitude, indicating an interaction of bile acids with a region close to the channel pore. Analysis of the known ASIC1 (acid-sensing ion channel) crystal structure suggested that bile acids may bind to the pore region at the degenerin site of ENaC. Substitution of a single amino acid residue within the degenerin region of βENaC (N521C or N521A) significantly reduced the stimulatory effect of bile acids on ENaC, suggesting that this site is critical for the functional interaction of bile acids with the channel.
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Affiliation(s)
- Alexandr V Ilyaskin
- From the Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Alexei Diakov
- From the Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Christoph Korbmacher
- From the Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Silke Haerteis
- From the Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
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Nesterov V, Krueger B, Bertog M, Dahlmann A, Palmisano R, Korbmacher C. In Liddle Syndrome, Epithelial Sodium Channel Is Hyperactive Mainly in the Early Part of the Aldosterone-Sensitive Distal Nephron. Hypertension 2016; 67:1256-62. [DOI: 10.1161/hypertensionaha.115.07061] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 03/16/2016] [Indexed: 11/16/2022]
Affiliation(s)
- Viatcheslav Nesterov
- From the Institut für Zelluläre und Molekulare Physiologie (V.N., B.K., M.B., C.K.), Universitätsklinikum Erlangen, Medizinische Klinik 4–Nephrologie und Hypertensiologie (A.D.), and Optical Imaging Center Erlangen (OICE) (R.P.), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Bettina Krueger
- From the Institut für Zelluläre und Molekulare Physiologie (V.N., B.K., M.B., C.K.), Universitätsklinikum Erlangen, Medizinische Klinik 4–Nephrologie und Hypertensiologie (A.D.), and Optical Imaging Center Erlangen (OICE) (R.P.), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Marko Bertog
- From the Institut für Zelluläre und Molekulare Physiologie (V.N., B.K., M.B., C.K.), Universitätsklinikum Erlangen, Medizinische Klinik 4–Nephrologie und Hypertensiologie (A.D.), and Optical Imaging Center Erlangen (OICE) (R.P.), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Anke Dahlmann
- From the Institut für Zelluläre und Molekulare Physiologie (V.N., B.K., M.B., C.K.), Universitätsklinikum Erlangen, Medizinische Klinik 4–Nephrologie und Hypertensiologie (A.D.), and Optical Imaging Center Erlangen (OICE) (R.P.), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Ralf Palmisano
- From the Institut für Zelluläre und Molekulare Physiologie (V.N., B.K., M.B., C.K.), Universitätsklinikum Erlangen, Medizinische Klinik 4–Nephrologie und Hypertensiologie (A.D.), and Optical Imaging Center Erlangen (OICE) (R.P.), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Christoph Korbmacher
- From the Institut für Zelluläre und Molekulare Physiologie (V.N., B.K., M.B., C.K.), Universitätsklinikum Erlangen, Medizinische Klinik 4–Nephrologie und Hypertensiologie (A.D.), and Optical Imaging Center Erlangen (OICE) (R.P.), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
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47
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Chen D, Stegbauer J, Sparks MA, Kohan D, Griffiths R, Herrera M, Gurley SB, Coffman TM. Impact of Angiotensin Type 1A Receptors in Principal Cells of the Collecting Duct on Blood Pressure and Hypertension. Hypertension 2016; 67:1291-7. [PMID: 27141055 DOI: 10.1161/hypertensionaha.115.06987] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/16/2016] [Indexed: 01/09/2023]
Abstract
The main actions of the renin-angiotensin system to control blood pressure (BP) are mediated by the angiotensin type 1 receptors (AT1Rs). The major murine AT1R isoform, AT1AR, is expressed throughout the nephron, including the collecting duct in both principal and intercalated cells. Principal cells play the major role in sodium and water reabsorption. Although aldosterone is considered to be the dominant regulator of sodium reabsorption by principal cells, recent studies suggest a role for direct actions of AT1R. To specifically examine the contributions of AT1AR in principal cells to BP regulation and the development of hypertension in vivo, we generated inbred 129/SvEv mice with deletion of AT1AR from principal cells (PCKO). At baseline, we found that BPs measured by radiotelemetry were similar between PCKOs and controls. During 1-week of low-salt diet (<0.02% NaCl), BPs fell significantly (P<0.05) and to a similar extent in both groups. On a high-salt (6% NaCl) diet, BP increased but was not different between groups. During the initial phase of angiotensin II-dependent hypertension, there was a modest but significant attenuation of hypertension in PCKOs (163±6 mm Hg) compared with controls (178±2 mm Hg; P<0.05) that was associated with enhanced natriuresis and decreased alpha epithelial sodium channel activation in the medulla of PCKOs. However, from day 9 onward, BPs were indistinguishable between groups. Although effects of AT1AR on baseline BP and adaptation to changes in dietary salt are negligible, our studies suggest that direct actions of AT1AR contribute to the initiation of hypertension and epithelial sodium channel activation.
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Affiliation(s)
- Daian Chen
- From the Division of Nephrology, Department of Medicine, Duke University, and Durham VA Medical Centers, NC (D.C., M.A.S., R.G., M.H., S.B.G., T.M.C.); Department of Nephrology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany (J.S.); School of Medicine, University of Utah Health Sciences Center, Salt Lake City (D.K.); and Cardiovascular and Metabolic Disorders Research Program, Duke-NUS Graduate Medical School, Singapore, Singapore (T.M.C.)
| | - Johannes Stegbauer
- From the Division of Nephrology, Department of Medicine, Duke University, and Durham VA Medical Centers, NC (D.C., M.A.S., R.G., M.H., S.B.G., T.M.C.); Department of Nephrology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany (J.S.); School of Medicine, University of Utah Health Sciences Center, Salt Lake City (D.K.); and Cardiovascular and Metabolic Disorders Research Program, Duke-NUS Graduate Medical School, Singapore, Singapore (T.M.C.)
| | - Matthew A Sparks
- From the Division of Nephrology, Department of Medicine, Duke University, and Durham VA Medical Centers, NC (D.C., M.A.S., R.G., M.H., S.B.G., T.M.C.); Department of Nephrology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany (J.S.); School of Medicine, University of Utah Health Sciences Center, Salt Lake City (D.K.); and Cardiovascular and Metabolic Disorders Research Program, Duke-NUS Graduate Medical School, Singapore, Singapore (T.M.C.)
| | - Donald Kohan
- From the Division of Nephrology, Department of Medicine, Duke University, and Durham VA Medical Centers, NC (D.C., M.A.S., R.G., M.H., S.B.G., T.M.C.); Department of Nephrology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany (J.S.); School of Medicine, University of Utah Health Sciences Center, Salt Lake City (D.K.); and Cardiovascular and Metabolic Disorders Research Program, Duke-NUS Graduate Medical School, Singapore, Singapore (T.M.C.)
| | - Robert Griffiths
- From the Division of Nephrology, Department of Medicine, Duke University, and Durham VA Medical Centers, NC (D.C., M.A.S., R.G., M.H., S.B.G., T.M.C.); Department of Nephrology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany (J.S.); School of Medicine, University of Utah Health Sciences Center, Salt Lake City (D.K.); and Cardiovascular and Metabolic Disorders Research Program, Duke-NUS Graduate Medical School, Singapore, Singapore (T.M.C.)
| | - Marcela Herrera
- From the Division of Nephrology, Department of Medicine, Duke University, and Durham VA Medical Centers, NC (D.C., M.A.S., R.G., M.H., S.B.G., T.M.C.); Department of Nephrology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany (J.S.); School of Medicine, University of Utah Health Sciences Center, Salt Lake City (D.K.); and Cardiovascular and Metabolic Disorders Research Program, Duke-NUS Graduate Medical School, Singapore, Singapore (T.M.C.)
| | - Susan B Gurley
- From the Division of Nephrology, Department of Medicine, Duke University, and Durham VA Medical Centers, NC (D.C., M.A.S., R.G., M.H., S.B.G., T.M.C.); Department of Nephrology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany (J.S.); School of Medicine, University of Utah Health Sciences Center, Salt Lake City (D.K.); and Cardiovascular and Metabolic Disorders Research Program, Duke-NUS Graduate Medical School, Singapore, Singapore (T.M.C.)
| | - Thomas M Coffman
- From the Division of Nephrology, Department of Medicine, Duke University, and Durham VA Medical Centers, NC (D.C., M.A.S., R.G., M.H., S.B.G., T.M.C.); Department of Nephrology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany (J.S.); School of Medicine, University of Utah Health Sciences Center, Salt Lake City (D.K.); and Cardiovascular and Metabolic Disorders Research Program, Duke-NUS Graduate Medical School, Singapore, Singapore (T.M.C.).
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MEC-10 and MEC-19 Reduce the Neurotoxicity of the MEC-4(d) DEG/ENaC Channel in Caenorhabditis elegans. G3-GENES GENOMES GENETICS 2016; 6:1121-30. [PMID: 27172609 PMCID: PMC4825646 DOI: 10.1534/g3.115.023507] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The Caenorhabditis elegans DEG/ENaC proteins MEC-4 and MEC-10 transduce gentle touch in the six touch receptor neurons .
Gain-of-function mutations of mec-4 and mec-4(d) result in a hyperactive channel and
neurodegeneration in vivo. Loss of MEC-6, a putative DEG/ENaC-specific chaperone, and of the similar
protein POML-1 suppresses the neurodegeneration caused by a mec-4(d) mutation. We find that mutation of two genes,
mec-10 and a new gene mec-19 (previously named C49G9.1), prevents this action of POML-1, allowing the touch receptor neurons to die in
poml-1mec-4(d) animals. The proteins encoded by these genes
normally inhibit mec-4(d) neurotoxicity through different mechanisms.
MEC-10, a subunit of the mechanosensory transduction channel with
MEC-4, inhibits MEC-4(d) activity without affecting MEC-4 expression. In contrast, MEC-19, a membrane protein specific to nematodes, inhibits MEC-4(d) activity and reduces MEC-4 surface expression.
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Grahammer F, Nesterov V, Ahmed A, Steinhardt F, Sandner L, Arnold F, Cordts T, Negrea S, Bertog M, Ruegg MA, Hall MN, Walz G, Korbmacher C, Artunc F, Huber TB. mTORC2 critically regulates renal potassium handling. J Clin Invest 2016; 126:1773-82. [PMID: 27043284 DOI: 10.1172/jci80304] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 02/18/2016] [Indexed: 12/12/2022] Open
Abstract
The mTOR pathway orchestrates cellular homeostasis. The rapamycin-sensitive mTOR complex (mTORC1) in the kidney has been widely studied; however, mTORC2 function in renal tubules is poorly characterized. Here, we generated mice lacking mTORC2 in the distal tubule (Rictorfl/fl Ksp-Cre mice), which were viable and had no obvious phenotype, except for a 2.5-fold increase in plasma aldosterone. Challenged with a low-Na+ diet, these mice adequately reduced Na+ excretion; however, Rictorfl/fl Ksp-Cre mice rapidly developed hyperkalemia on a high-K+ diet, despite a 10-fold increase in serum aldosterone levels, implying that mTORC2 regulates kaliuresis. Phosphorylation of serum- and glucocorticoid-inducible kinase 1 (SGK1) and PKC-α was absent in Rictorfl/fl Ksp-Cre mice, indicating a functional block in K+ secretion activation via ROMK channels. Indeed, patch-clamp experiments on split-open tubular segments from the transition zone of the late connecting tubule and early cortical collecting duct demonstrated that Ba2+-sensitive apical K+ currents were barely detectable in the majority of Rictorfl/fl Ksp-Cre mice. Conversely, epithelial sodium channel (ENaC) activity was largely preserved, suggesting that the reduced ability to maintain K+ homeostasis is the result of impaired apical K+ conductance and not a reduced electrical driving force for K+ secretion. Thus, these data unravel a vital and nonredundant role of mTORC2 for distal tubular K+ handling.
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50
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Plasma membrane insertion of epithelial sodium channels occurs with dual kinetics. Pflugers Arch 2016; 468:859-70. [DOI: 10.1007/s00424-016-1799-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 02/04/2016] [Accepted: 02/08/2016] [Indexed: 01/05/2023]
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