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Albritton CF, Demirci M, Neikirk K, Ertuglu LA, Ishimwe JA, Mutchler AL, Sheng Q, Laffer CL, Wanjalla CN, Ahmed T, Haynes AP, Saleem M, Beasley HK, Marshall AG, Vue Z, Ikizler AT, Kleyman TR, Kon V, Hinton A, Kirabo A. Myeloid Cell Glucocorticoid, Not Mineralocorticoid Receptor Signaling, Contributes to Salt-Sensitive Hypertension in Humans via Cortisol. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.10.598374. [PMID: 38915603 PMCID: PMC11195113 DOI: 10.1101/2024.06.10.598374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
BACKGROUND Salt sensitivity of blood pressure (SSBP) is an independent risk factor for cardiovascular morbidity and mortality, yet the etiology is poorly understood. We previously found that serum/glucocorticoid-regulated kinase 1 (SGK1) and epoxyeicosatrienoic acids (EETs) regulate epithelial sodium channel (ENaC)-dependent sodium entry into monocyte-derived antigen-presenting cells (APCs) and activation of NADPH oxidase, leading to the formation of isolevuglandins (IsoLGs) in SSBP. Whereas aldosterone via the mineralocorticoid receptor (MR) activates SGK1 leading to hypertension, our past findings indicate that levels of plasma aldosterone do not correlate with SSBP, and there is little to no MR expression in APCs. Thus, we hypothesized that cortisol acting via the glucocorticoid receptor (GR), not the MR in APCs mediates SGK1 actions to induce SSBP. METHODS We performed cellular indexing of transcriptomes and epitopes by sequencing (CITE-Seq) analysis on peripheral blood mononuclear cells of humans rigorously phenotyped for SSBP using an inpatient salt loading/depletion protocol to determine expression of MR, GR, and SGK1 in immune cells. In additional experiments, we performed bulk transcriptomic analysis on isolated human monocytes following in vitro treatment with high salt from a separate cohort. We then measured urine and plasma cortisol, cortisone, renin, and aldosterone. Subsequently, we measured the association of these hormones with changes in systolic, diastolic, mean arterial pressure and pulse pressure as well as immune cell activation via IsoLG formation. RESULTS We found that myeloid APCs predominantly express the GR and SGK1 with no expression of the MR. Expression of the GR in APCs increased after salt loading and decreased with salt depletion in salt-sensitive but not salt-resistant people and was associated with increased expression of SGK1. Moreover, we found that plasma and urine cortisol/cortisone but not aldosterone/renin correlated with SSBP and APCs activation via IsoLGs. We also found that cortisol negatively correlates with EETs. CONCLUSION Our findings suggest that renal cortisol signaling via the GR but not the MR in APCs contributes to SSBP via cortisol. Urine and plasma cortisol may provide an important currently unavailable feasible diagnostic tool for SSBP. Moreover, cortisol-GR-SGK1-ENaC signaling pathway may provide treatment options for SSBP.
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Affiliation(s)
- Claude F. Albritton
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37212-8802, USA
- Department of Biomedical Sciences, School of Graduate Studies, Meharry Medical College, Nashville, TN 37208-3501, USA
| | - Mert Demirci
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Kit Neikirk
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, TN 37212-8802, USA
| | - Lale A. Ertuglu
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Jeanne A Ishimwe
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37212-8802, USA
| | - Ashley L Mutchler
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37212-8802, USA
| | - Quanhu Sheng
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN 37212-8802, USA
| | - Cheryl L Laffer
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37212-8802, USA
| | - Celestine N. Wanjalla
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37212-8802, USA
| | - Taseer Ahmed
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37212-8802, USA
- Department of Pharmacology, College of Pharmacy, University of Sargodha, University Road, Sargodha, Punjab, 40100, Pakistan
| | - Alexandria Porcia Haynes
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37212-8802, USA
| | - Mohammad Saleem
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37212-8802, USA
| | - Heather K. Beasley
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, TN 37212-8802, USA
| | - Andrea G. Marshall
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, TN 37212-8802, USA
| | - Zer Vue
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, TN 37212-8802, USA
| | - Alp T Ikizler
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Thomas R. Kleyman
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Valentina Kon
- Division of Nephrology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN
| | - Antentor Hinton
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, TN 37212-8802, USA
| | - Annet Kirabo
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37212-8802, USA
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, TN 37212-8802, USA
- Vanderbilt Center for Immunobiology
- Vanderbilt Institute for Infection, Immunology and Inflammation
- Vanderbilt Institute for Global Health
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2
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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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3
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Mohammadifard N, Moazeni F, Azizian-Farsani F, Gharipour M, Khosravi E, Sadeghian L, Mansouri A, Shirani S, Sarrafzadegan N. Genetic variation in salt taste receptors impact salt intake and blood pressure. Sci Rep 2023; 13:4037. [PMID: 36899055 PMCID: PMC10006406 DOI: 10.1038/s41598-022-23827-0] [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: 08/13/2021] [Accepted: 03/14/2022] [Indexed: 03/12/2023] Open
Abstract
So far, few studies have examined the effect of salt taste receptors genetic variation on dietary intake in the Iranian population. We aimed to evaluate associations between single nucleotide polymorphisms (SNPs) in salt taste receptors' genes with dietary salt intake and blood pressure. A cross-sectional study was carried out among 116 randomly selected healthy adults aged ≥ 18 in Isfahan, Iran. Participants underwent sodium intake determination by 24-h urine collection, as well as dietary assessment by semi-quantitative food frequency questionnaire and blood pressure measurement. Whole blood was collected to extract DNA and genotype of SNP rs239345 in SCNN1B and rs224534, rs4790151 and rs8065080 in TRPV1 gene. Sodium consumption and diastolic blood pressure were significantly higher in carriers of the A-allele in rs239345 compared to subjects with the TT genotype (4808.4 ± 824.4 mg/day vs. 4043.5 ± 989.3 mg/day; P = 0.004) and 83.6 ± 8.5 mmHg vs. 77.3 ± 7.3 mmHg; P = 0.011), respectively. The level of sodium intake was lower in the TT genotype of TRPV1 (rs224534) than the CC genotype (3767.0 ± 713.7 mg/day vs. 4633.3 ± 793.5 mg/day; P = 0.012). We could not find any association between genotypes of all SNPs with systolic blood pressure as well as genotypes of rs224534, rs4790151 and rs8065080 with diastolic blood pressure. Genetic variations can relate with salt intake and consequently may associate with hypertension and finally cardiovascular disease risk in the Iranian population.
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Affiliation(s)
- Noushin Mohammadifard
- Isfahan Cardiovascular Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Faezeh Moazeni
- Department of Clinical Nutrition, School of Nutrition and Food Science, Food Security Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Fatemeh Azizian-Farsani
- Interventional Cardiology Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mojgan Gharipour
- Cardiac Rehabilitation Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Elham Khosravi
- Heart Failure Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Ladan Sadeghian
- Perdiatric Cardiovascular Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Asieh Mansouri
- Hypertension Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Shahin Shirani
- Department of Cardiology, Tehran University of Medical Science, Dr Ali Shariati Hospital, Tehran, Iran.
| | - Nizal Sarrafzadegan
- Isfahan Cardiovascular Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran
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Van Beusecum JP, Rianto F, Teakell J, Kon V, Sparks MA, Hoorn EJ, Kirabo A, Ramkumar N. Novel Concepts in Nephron Sodium Transport: A Physiological and Clinical Perspective. ADVANCES IN KIDNEY DISEASE AND HEALTH 2023; 30:124-136. [PMID: 36868728 DOI: 10.1053/j.akdh.2022.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 12/15/2022] [Accepted: 12/15/2022] [Indexed: 04/13/2023]
Abstract
The kidneys play a critical role in maintaining total body sodium (Na+) balance across a wide range of dietary intake, accomplished by a concerted effort involving multiple Na+ transporters along the nephron. Furthermore, nephron Na+ reabsorption and urinary Na+ excretion are closely linked to renal blood flow and glomerular filtration such that perturbations in either of them can modify Na+ transport along the nephron, ultimately resulting in hypertension and other Na+-retentive states. In this article, we provide a brief physiological overview of nephron Na+ transport and illustrate clinical syndromes and therapeutic agents that affect Na+ transporter function. We highlight recent advances in kidney Na+ transport, particularly the role of immune cells, lymphatics, and interstitial Na+ in regulating Na+ reabsorption, the emergence of potassium (K+) as a regulator of Na+ transport, and the evolution of the nephron to modulate Na+ transport.
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Affiliation(s)
- Justin P Van Beusecum
- Ralph H. Johnson VA Medical Center, Charleston, SC; Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, SC
| | - Fitra Rianto
- Division of Nephrology, Department of Medicine, Duke University School of Medicine and Renal Section, Durham VA Health Care System Durham, Durham, NC
| | - Jade Teakell
- Division of Renal Diseases and Hypertension, Department of Medicine, McGovern Medical School, University of Texas Health Science Center, Houston, TX
| | - Valentina Kon
- Division of Nephrology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN
| | - Matthew A Sparks
- Division of Nephrology, Department of Medicine, Duke University School of Medicine and Renal Section, Durham VA Health Care System Durham, Durham, NC
| | - Ewout J Hoorn
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Annet Kirabo
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Nirupama Ramkumar
- Division of Nephrology and Hypertension, Department of Medicine, University of Utah Health, Salt Lake City, UT.
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5
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Mrowka R. An update on hypertension. Acta Physiol (Oxf) 2023; 237:e13942. [PMID: 36709490 DOI: 10.1111/apha.13942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 01/25/2023] [Indexed: 01/30/2023]
Affiliation(s)
- Ralf Mrowka
- AG Experimentelle Nephrologie, Friedrich-Schiller-Universität Jena, Universitätsklinikum Jena, KIMIII, Thüringen, Jena, Germany
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6
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Siddiqui A, Dundar H, Sharma J, Kaczmarczyk A, Echols J, Dai Y, Sun CR, Du M, Liu Z, Zhao R, Wood T, Sanders S, Rasmussen L, Bostwick JR, Augelli-Szafran C, Suto M, Rowe SM, Bedwell DM, Keeling KM. Triamterene Functions as an Effective Nonsense Suppression Agent for MPS I-H (Hurler Syndrome). Int J Mol Sci 2023; 24:4521. [PMID: 36901952 PMCID: PMC10003437 DOI: 10.3390/ijms24054521] [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: 02/03/2023] [Revised: 02/20/2023] [Accepted: 02/22/2023] [Indexed: 03/03/2023] Open
Abstract
Mucopolysaccharidosis I-Hurler (MPS I-H) is caused by the loss of α-L-iduronidase, a lysosomal enzyme that degrades glycosaminoglycans. Current therapies cannot treat many MPS I-H manifestations. In this study, triamterene, an FDA-approved, antihypertensive diuretic, was found to suppress translation termination at a nonsense mutation associated with MPS I-H. Triamterene rescued enough α-L-iduronidase function to normalize glycosaminoglycan storage in cell and animal models. This new function of triamterene operates through premature termination codon (PTC) dependent mechanisms that are unaffected by epithelial sodium channel activity, the target of triamterene's diuretic function. Triamterene represents a potential non-invasive treatment for MPS I-H patients carrying a PTC.
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Affiliation(s)
- Amna Siddiqui
- Department of Biochemistry & Molecular Genetics, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Halil Dundar
- Department of Biochemistry & Molecular Genetics, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Next Generation Sequencing Transplant Diagnostics, Thermo-Fisher Scientific, West Hills, CA 91304, USA
| | - Jyoti Sharma
- Cystic Fibrosis Research Center, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Division of Infectious Diseases, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Aneta Kaczmarczyk
- Department of Biochemistry & Molecular Genetics, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- ARUP Laboratories, Department of Pathology, University of Utah, Salt Lake City, UT 84112, USA
| | - Josh Echols
- Department of Biochemistry & Molecular Genetics, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Yanying Dai
- Department of Biochemistry & Molecular Genetics, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Chuanxi Richard Sun
- Department of Biochemistry & Molecular Genetics, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Ming Du
- Department of Biochemistry & Molecular Genetics, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Cystic Fibrosis Research Center, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Zhong Liu
- Department of Biochemistry & Molecular Genetics, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Rui Zhao
- Department of Biochemistry & Molecular Genetics, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Tim Wood
- Greenwood Genetic Center, Greenwood, SC 29646, USA
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | | | | | | | | | - Mark Suto
- Southern Research, Birmingham, AL 35205, USA
| | - Steven M. Rowe
- Cystic Fibrosis Research Center, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - David M. Bedwell
- Department of Biochemistry & Molecular Genetics, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Cystic Fibrosis Research Center, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Kim M. Keeling
- Department of Biochemistry & Molecular Genetics, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Cystic Fibrosis Research Center, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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7
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Ertuglu LA, Kirabo A. Dendritic Cell Epithelial Sodium Channel in Inflammation, Salt-Sensitive Hypertension, and Kidney Damage. KIDNEY360 2022; 3:1620-1629. [PMID: 36245645 PMCID: PMC9528365 DOI: 10.34067/kid.0001272022] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/24/2022] [Indexed: 11/27/2022]
Abstract
Salt-sensitive hypertension is a major risk factor for cardiovascular morbidity and mortality. The pathophysiologic mechanisms leading to different individual BP responses to changes in dietary salt remain elusive. Research in the last two decades revealed that the immune system plays a critical role in the development of hypertension and related end organ damage. Moreover, sodium accumulates nonosmotically in human tissue, including the skin and muscle, shifting the dogma on body sodium balance and its regulation. Emerging evidence suggests that high concentrations of extracellular sodium can directly trigger an inflammatory response in antigen-presenting cells (APCs), leading to hypertension and vascular and renal injury. Importantly, sodium entry into APCs is mediated by the epithelial sodium channel (ENaC). Although the role of the ENaC in renal regulation of sodium excretion and BP is well established, these new findings imply that the ENaC may also exert BP modulatory effects in extrarenal tissue through an immune-dependent pathway. In this review, we discuss the recent advances in our understanding of the pathophysiology of salt-sensitive hypertension with a particular focus on the roles of APCs and the extrarenal ENaC.
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8
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Mutengo KH, Masenga SK, Mwesigwa N, Patel KP, Kirabo A. Hypertension and human immunodeficiency virus: A paradigm for epithelial sodium channels? Front Cardiovasc Med 2022; 9:968184. [PMID: 36093171 PMCID: PMC9452753 DOI: 10.3389/fcvm.2022.968184] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 08/10/2022] [Indexed: 02/03/2023] Open
Abstract
Hypertension is a risk factor for end organ damage and death and is more common in persons with HIV compared to the general population. Several mechanisms have been studied in the pathogenesis of hypertension. Current evidence suggests that the epithelial sodium channel (ENaC) plays a key role in regulating blood pressure through the transport of sodium and water across membranes in the kidney tubules, resulting in retention of sodium and water and an altered fluid balance. However, there is scarcity of information that elucidates the role of ENaC in HIV as it relates to increasing the risk for development or pathogenesis of hypertension. This review summarized the evidence to date implicating a potential role for altered ENaC activity in contributing to hypertension in patients with HIV.
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Affiliation(s)
- Katongo H. Mutengo
- School of Medicine and Health Sciences, HAND Research Group, Mulungushi University, Livingstone Campus, Livingstone, Zambia,School of Public Health and Medicine, University of Zambia, Lusaka, Zambia
| | - Sepiso K. Masenga
- School of Medicine and Health Sciences, HAND Research Group, Mulungushi University, Livingstone Campus, Livingstone, Zambia,School of Public Health and Medicine, University of Zambia, Lusaka, Zambia
| | - Naome Mwesigwa
- Department of Medicine and Dentistry, Kampala International University, Kampala, Uganda
| | - Kaushik P. Patel
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Annet Kirabo
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States,*Correspondence: Annet Kirabo,
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9
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Warner ER, Aloor FZ, Satapathy SK. A narrative review of nutritional abnormalities, complications, and optimization in the cirrhotic patient. Transl Gastroenterol Hepatol 2022; 7:5. [PMID: 35243114 PMCID: PMC8826036 DOI: 10.21037/tgh-20-325] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 04/08/2021] [Indexed: 08/10/2023] Open
Abstract
OBJECTIVE The purpose of this manuscript is to identify the pathophysiology of the metabolic abnormalities observed in cirrhosis and to uncover associations, if any, to its complications, such as sarcopenia and hepatic encephalopathy (HE). BACKGROUND Liver dysfunction in cirrhosis is known to be a precipitating factor in the disruption of many physiological pathways, specifically nutrient metabolism. As a result, affected patients are highly susceptible to derangements of processes affecting multiple classes of macro- and micronutrients, including proteins, carbohydrates, electrolytes, vitamins, and minerals. These disruptions are thought to be contributory to the pathogenesis of known complications of cirrhosis. METHODS Literature research of relevant topics was conducted for the above stated objective; sources were limited to articles from peer-reviewed journals published within the last 30 years. CONCLUSION This research established that there is positive correlation between nutrient derangements and the increased risk of complications of cirrhosis, which themselves carry significant morbidity and mortality risk. It also established that some nutrient and electrolyte abnormalities are independent indicators of prognosis and adverse outcomes, such as mortality. This also highlights the importance of comprehension of anomalous metabolism and its complications as it necessitates serious consideration in clinical care. In addition to medical management, cirrhotic patients also require ancillary assessment, such as comprehensive nutritional evaluation, to identify and treat reversible nutritional derangements. This consideration provides the best opportunity to achieve maximal health outcomes in the cirrhotic patient population.
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Affiliation(s)
- Edgewood R. Warner
- Department of Medicine, Donald and Barbara Zucker School of Medicine/Northwell Health, Manhasset, NY, USA
| | | | - Sanjaya K. Satapathy
- Division of Hepatology and Sandra Atlas Bass Center for Liver Diseases and Transplantation, Department of Medicine, Donald and Barbara Zucker School of Medicine/Northwell Health, Manhasset, New York, USA
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10
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Xu X, Eales JM, Jiang X, Sanderson E, Drzal M, Saluja S, Scannali D, Williams B, Morris AP, Guzik TJ, Charchar FJ, Holmes MV, Tomaszewski M. Contributions of obesity to kidney health and disease: insights from Mendelian randomization and the human kidney transcriptomics. Cardiovasc Res 2021; 118:3151-3161. [PMID: 34893803 PMCID: PMC9732514 DOI: 10.1093/cvr/cvab357] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 12/06/2021] [Indexed: 12/16/2022] Open
Abstract
AIMS Obesity and kidney diseases are common complex disorders with an increasing clinical and economic impact on healthcare around the globe. Our objective was to examine if modifiable anthropometric obesity indices show putatively causal association with kidney health and disease and highlight biological mechanisms of potential relevance to the association between obesity and the kidney. METHODS AND RESULTS We performed observational, one-sample, two-sample Mendelian randomization (MR) and multivariable MR studies in ∼300 000 participants of white-British ancestry from UK Biobank and participants of predominantly European ancestry from genome-wide association studies. The MR analyses revealed that increasing values of genetically predicted body mass index and waist circumference were causally associated with biochemical indices of renal function, kidney health index (a composite renal outcome derived from blood biochemistry, urine analysis, and International Classification of Disease-based kidney disease diagnoses), and both acute and chronic kidney diseases of different aetiologies including hypertensive renal disease and diabetic nephropathy. Approximately 13-16% and 21-26% of the potentially causal effect of obesity indices on kidney health were mediated by blood pressure and type 2 diabetes, respectively. A total of 61 pathways mapping primarily onto transcriptional/translational regulation, innate and adaptive immunity, and extracellular matrix and metabolism were associated with obesity measures in gene set enrichment analysis in up to 467 kidney transcriptomes. CONCLUSIONS Our data show that a putatively causal association of obesity with renal health is largely independent of blood pressure and type 2 diabetes and uncover the signatures of obesity on the transcriptome of human kidney.
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Affiliation(s)
- Xiaoguang Xu
- Division of Cardiovascular Sciences, Faculty of Medicine, Biology and Health, University of Manchester, AV Hill Building, Manchester, M13 9PT, UK
| | - James M Eales
- Division of Cardiovascular Sciences, Faculty of Medicine, Biology and Health, University of Manchester, AV Hill Building, Manchester, M13 9PT, UK
| | - Xiao Jiang
- Division of Cardiovascular Sciences, Faculty of Medicine, Biology and Health, University of Manchester, AV Hill Building, Manchester, M13 9PT, UK
| | - Eleanor Sanderson
- MRC Integrative Epidemiology Unit, University of Bristol, Oakfield House, Bristol, BS8 2BN, UK
| | - Maciej Drzal
- Division of Cardiovascular Sciences, Faculty of Medicine, Biology and Health, University of Manchester, AV Hill Building, Manchester, M13 9PT, UK
| | - Sushant Saluja
- Division of Cardiovascular Sciences, Faculty of Medicine, Biology and Health, University of Manchester, AV Hill Building, Manchester, M13 9PT, UK
| | - David Scannali
- Division of Cardiovascular Sciences, Faculty of Medicine, Biology and Health, University of Manchester, AV Hill Building, Manchester, M13 9PT, UK
| | - Bryan Williams
- Institute of Cardiovascular Sciences, University College London, Roger Williams Building, London, WC1E 6HX, UK
| | - Andrew P Morris
- Centre for Genetics and Genomics Versus Arthritis, Centre for Musculoskeletal Research, Division of Musculoskeletal & Dermatological Sciences, Faculty of Medicine, Biology and Health, University of Manchester, AV Hill Building, Manchester, M13 9PT, UK
| | - Tomasz J Guzik
- BHF Glasgow Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8TA, UK,Department of Internal and Agricultural Medicine, Jagiellonian University College of Medicine, Skarbowa 1, 31-121 Kraków, Poland
| | - Fadi J Charchar
- School of Science, Psychology and Sport, Federation University, Ballarat, Victoria, 3353, Australia,Department of Cardiovascular Sciences, University of Leicester, University Road, Leicester, LE1 7RH, UK,Department of Physiology, University of Melbourne, Medical Building 181, Melbourne, Victoria, 3010, Australia
| | - Michael V Holmes
- NIHR Oxford Biomedical Research Centre, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Oxford, OX4 2PG, UK,Medical Research Council Population Health Research Unit at the University of Oxford, Nuffield Department of Population Health, University of Oxford, Oxford, OX3 7LF, UK,Clinical Trial Service Unit & Epidemiological Studies Unit (CTSU), Nuffield Department of Population Health, University of Oxford, Big Data Institute Building, Roosevelt Drive, Oxford, OX3 7LF, UK
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11
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Corrêa JWN, Boaro KR, Sene LB, Polidoro JZ, Salles TA, Martins FL, Bendhack LM, Girardi ACC. Antiproteinuric and Hyperkalemic Mechanisms Activated by Dual Versus Single Blockade of the RAS in Renovascular Hypertensive Rats. Front Physiol 2021; 12:656460. [PMID: 34177612 PMCID: PMC8221266 DOI: 10.3389/fphys.2021.656460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 04/09/2021] [Indexed: 11/24/2022] Open
Abstract
This study aimed to investigate the antiproteinuric and hyperkalemic mechanisms activated by dual renin-angiotensin system (RAS) blockade in renovascular hypertensive rats (2-kidney 1-clip model [2K-1C]). Six weeks after clipping the left renal artery or sham operation (2K), rats were treated with losartan, enalapril, or both drugs for two weeks. We found that 2K-1C rats displayed higher tail-cuff blood pressure (BP), increased non-clipped kidney Ang II concentration, and more pronounced urinary albumin excretion than 2K. BP was decreased by the treatment with either enalapril or losartan, and the combination of both drugs promoted an additional antihypertensive effect in 2K-1C rats. Renal Ang II content and albuminuria were reduced by either enalapril or losartan in monotherapy and restored to control levels by dual RAS blockade. Albuminuria in 2K-1C rats was accompanied by downregulation of the glomerular slit protein podocin, reduction of the endocytic receptors megalin and cubilin, and a marked decrease in the expression of the ClC-5 chloride channel, compared to 2K animals. Treatment with losartan and enalapril in monotherapy or combination increased the expression of podocin, cubilin, and ClC-5. However, only the combined therapy normalized podocin, cubilin, and ClC-5 protein abundance in the non-clipped kidney of 2K-1C rats. Renovascular hypertensive 2K-1C rats had a lower concentration of plasma potassium compared to 2K rats. Single RAS blockade normalized potassium plasma concentration, whereas 2K-1C rats treated with dual RAS blockade exhibited hyperkalemia. Hypokalemia in 2K-1C rats was accompanied by an increase in the cleaved activated forms of α-ENaC and γ-ENaC and the expression of β-ENaC. Combined RAS blockade but not monotherapy significantly reduced the expression of these ENaC subunits in 2K-1C rats. Indeed, double RAS blockade reduced the abundance of cleaved-α-ENaC to levels lower than those of 2K rats. Collectively, these results demonstrate that the antiproteinuric effect of dual RAS blockade in 2K-1C rats is associated with the restored abundance of podocin and cubilin, and ClC-5. Moreover, double RAS blockade-induced hyperkalemia may be due, at least partially, to an exaggerated downregulation of cleaved α-ENaC in the non-clipped kidney of renovascular hypertensive rats.
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Affiliation(s)
- José Wilson N Corrêa
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor) University of São Paulo Medical School, São Paulo, Brazil.,Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Amazonas, Manaus, Brazil
| | - Karoline R Boaro
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor) University of São Paulo Medical School, São Paulo, Brazil
| | - Letícia B Sene
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor) University of São Paulo Medical School, São Paulo, Brazil
| | - Juliano Z Polidoro
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor) University of São Paulo Medical School, São Paulo, Brazil
| | - Thiago A Salles
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor) University of São Paulo Medical School, São Paulo, Brazil
| | - Flavia L Martins
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor) University of São Paulo Medical School, São Paulo, Brazil
| | - Lusiane M Bendhack
- Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | - Adriana C C Girardi
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor) University of São Paulo Medical School, São Paulo, Brazil
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12
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Zhang X, Zhao L, Jin R, Li M, Li MS, Li R, Liang X. CRISPR/Cas9-Mediated α-ENaC Knockout in a Murine Pancreatic β-Cell Line. Front Genet 2021; 12:664799. [PMID: 33868391 PMCID: PMC8047203 DOI: 10.3389/fgene.2021.664799] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 03/08/2021] [Indexed: 12/27/2022] Open
Abstract
Many ion channels participate in controlling insulin synthesis and secretion of pancreatic β-cells. Epithelial sodium channel (ENaC) expressed in human pancreatic tissue, but the biological role of ENaC in pancreatic β-cells is still unclear. Here, we applied the CRISPR/Cas9 gene editing technique to knockout α-ENaC gene in a murine pancreatic β-cell line (MIN6 cell). Four single-guide RNA (sgRNA) sites were designed for the exons of α-ENaC. The sgRNA1 and sgRNA3 with the higher activity were constructed and co-transfected into MIN6 cells. Through processing a series of experiment flow included drug screening, cloning, and sequencing, the α-ENaC gene-knockout (α-ENaC−/−) in MIN6 cells were obtained. Compared with the wild-type MIN6 cells, the cell viability and insulin content were significantly increased in α-ENaC−/− MIN6 cells. Therefore, α-ENaC−/− MIN6 cells generated by CRISPR/Cas9 technology added an effective tool to study the biological function of α-ENaC in pancreatic β-cells.
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Affiliation(s)
- Xue Zhang
- Department of Pathophysiology, Nanjing Medical University, Nanjing, China
| | - Lihua Zhao
- Jiangsu Key Laboratory of Xenotransplantation, Nanjing Medical University, Nanjing, China
| | - Runbing Jin
- Department of Pathophysiology, Nanjing Medical University, Nanjing, China
| | - Min Li
- Department of Pathophysiology, Nanjing Medical University, Nanjing, China
| | - Mei-Shuang Li
- Jiangsu Key Laboratory of Xenotransplantation, Nanjing Medical University, Nanjing, China
| | - Rongfeng Li
- Jiangsu Key Laboratory of Xenotransplantation, Nanjing Medical University, Nanjing, China
| | - Xiubin Liang
- Department of Pathophysiology, Nanjing Medical University, Nanjing, China.,Department of Nephrology, The Affiliated Sir Run Run Hospital of Nanjing Medical University, Nanjing, China
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13
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An increase in alveolar fluid clearance induced by hyperinsulinemia in obese rats with LPS-induced acute lung injury. Respir Physiol Neurobiol 2020; 279:103470. [PMID: 32474115 DOI: 10.1016/j.resp.2020.103470] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 05/07/2020] [Accepted: 05/25/2020] [Indexed: 01/11/2023]
Abstract
A lower mortality rate is observed in obese patients with acute lung injury (ALI), which is referred to as the obesity paradox, in several studies and recent meta-analyses. Hyperinsulinemia is characterized as the primary effect of obesity, and exogenous insulin attenuates LPS-induced pulmonary edema. The detailed mechanism responsible for the effect of hyperinsulinemia on pulmonary edema and alveolar filling needs to be elucidated. SD rats were fed with a high-fat diet (HFD) for a total of 14 weeks. SD rats were anesthetized and intraperitoneally injected with 10 mg/kg lipopolysaccharide (LPS), while control rats received only saline vehicle. Insulin receptor antagonist S961 (20 nmol/kg) was given by the tail vein and serum, and glucocorticoid-induced protein kinase-1 (SGK-1) inhibitor EMD638683 (20 mg/kg) was administrated intragastrically prior to LPS exposure. The lungs were isolated for the measurement of alveolar fluid clearance. The protein expression of epithelial sodium channel (ENaC) was detected by Western blot. Insulin level in serum was significantly higher in HFD rats compared with normal diet rats in the presence or absence of LPS pretreatment. Hyperinsulinemia induced by high fat feeding increased alveolar fluid clearance and the abundance of α-ENaC, β-ENaC, and γ-ENaC in both normal rats and ALI rats. Moreover, these effects were reversed in response to S961. EMD638683 prevented the simulation of alveolar fluid clearance and protein expression of ENaC in HFD rats with ALI. These findings suggest that hyperinsulinemia induced by obesity results in the stimulation of alveolar fluid clearance via the upregulation of the abundance of ENaC in clinical acute lung injury, whereas theses effects are prevented by an SGK-1 inhibitor.
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14
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Marunaka R, Marunaka Y. Interactive Actions of Aldosterone and Insulin on Epithelial Na + Channel Trafficking. Int J Mol Sci 2020; 21:ijms21103407. [PMID: 32408487 PMCID: PMC7279156 DOI: 10.3390/ijms21103407] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/08/2020] [Accepted: 05/09/2020] [Indexed: 11/29/2022] Open
Abstract
Epithelial Na+ channel (ENaC) participates in renal epithelial Na+ reabsorption, controlling blood pressure. Aldosterone and insulin elevate blood pressure by increasing the ENaC-mediated Na+ reabsorption. However, little information is available on the interactive action of aldosterone and insulin on the ENaC-mediated Na+ reabsorption. In the present study, we tried to clarify if insulin would modify the aldosterone action on the ENaC-mediated Na+ reabsorption from a viewpoint of intracellular ENaC trafficking. We measured the ENaC-mediated Na+ transport as short-circuit currents using a four-state mathematical ENaC trafficking model in renal A6 epithelial cells with or without aldosterone treatment under the insulin-stimulated and -unstimulated conditions. We found that: (A) under the insulin-stimulated condition, aldosterone treatment (1 µM for 20 h) significantly elevated the ENaC insertion rate to the apical membrane (kI) 3.3-fold and the ENaC recycling rate (kR) 2.0-fold, but diminished the ENaC degradation rate (kD) 0.7-fold without any significant effect on the ENaC endocytotic rate (kE); (B) under the insulin-unstimulated condition, aldosterone treatment decreased kE 0.5-fold and increased kR 1.4-fold, without any significant effect on kI or kD. Thus, the present study indicates that: (1) insulin masks the well-known inhibitory action of aldosterone on the ENaC endocytotic rate; (2) insulin induces a stimulatory action of aldosterone on ENaC apical insertion and an inhibitory action of aldosterone on ENaC degradation; (3) insulin enhances the aldosterone action on ENaC recycling; (4) insulin has a more effective action on diminution of ENaC endocytosis than aldosterone.
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Affiliation(s)
- Rie Marunaka
- Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto 604-8472, Japan;
- Okamura Dental Clinic, Chuo-ku, Osaka 541-0041, Japan
| | - Yoshinori Marunaka
- Research Institute for Clinical Physiology, Kyoto Industrial Health Association, Kyoto 604-8472, Japan;
- Research Center for Drug Discovery and Pharmaceutical Development Science, Research Organization of Science and Technology, Ritsumeikan University, Kusatsu 525-8577, Japan
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto 602-8566, Japan
- Correspondence: ; Tel.: +81-75-802-0135
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15
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Maestro I, Boya P, Martinez A. Serum- and glucocorticoid-induced kinase 1, a new therapeutic target for autophagy modulation in chronic diseases. Expert Opin Ther Targets 2020; 24:231-243. [PMID: 32067528 DOI: 10.1080/14728222.2020.1730328] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Introduction: Autophagy, a basic cellular degradation pathway essential for survival, is altered both in aging and in many chronic human diseases, including infections, cancer, heart disease, and neurodegeneration. Identifying new therapeutic targets for the control and modulation of autophagy events is therefore of utmost importance in drug discovery. Serum and glucocorticoid activated kinase 1 (SGK1), known for decades for its role in ion channel modulation, is now known to act as a switch for autophagy homeostasis, and has emerged as a novel and important therapeutic target likely to attract considerable research attention in the coming years.Areas covered: In this general review of SGK1 we describe the kinase's structure and its roles in physiological and pathological contexts. We also discuss small-molecule modulators of SGK1 activity. These modulators are of particular interest to medicinal chemists and pharmacists seeking to develop more potent and selective drug candidates for SGK1, which, despite its key role in autophagy, remains relatively understudied.Expert opinion: The main future challenges in this area are (i) deciphering the role of SGK1 in selective autophagy processes (e.g. mitophagy, lipophagy, and aggrephagy); (ii) identifying selective allosteric modulators of SGK1 with specific biological functions; and (iii) conducting first-in-man clinical studies.
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Affiliation(s)
- Inés Maestro
- Centro de Investigaciones Biológicas Margarita Salas-CSIC, Madrid, Spain
| | - Patricia Boya
- Centro de Investigaciones Biológicas Margarita Salas-CSIC, Madrid, Spain
| | - Ana Martinez
- Centro de Investigaciones Biológicas Margarita Salas-CSIC, Madrid, Spain.,Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
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16
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Chang HY, Su YW, Feng AN, Fong MC, Huang KC, Chong E, Chen KC, Yin WH. Prescription patterns of diabetes medications influencing clinical outcomes of heart failure patients with reduced ejection fraction. ESC Heart Fail 2020; 7:604-615. [PMID: 31995274 PMCID: PMC7160466 DOI: 10.1002/ehf2.12617] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 12/13/2019] [Accepted: 01/03/2020] [Indexed: 12/28/2022] Open
Abstract
Aims We collected the different prescription patterns of diabetes medications in a cohort of patients with heart failure with reduced ejection fraction (HFrEF) and analysed the impact of different prescription patterns on clinical outcomes. Methods and results Consecutive diabetic patients with HFrEF from a heart failure referral centre were retrospectively analysed between 2015 and 2016. Exclusion criteria include being lost to follow‐up, not receiving diabetes medications, and having severe renal impairment with a glomerular filtration rate < 30 mL/min/1.73 m2. Prescription of diabetes medications and the respective clinical outcomes were collected between 2016 and 2018. Among 381 patients (mean age, 64.8 ± 12.8 years; 71.9% male; mean left ventricular ejection fraction, 27.6 ± 7.0%; mean body mass index, 26.1 ± 4.7 kg/m2), the prescription rates of sodium‐glucose co‐transporter 2 inhibitor (SGLT2i) increased from 10.3% in 2016 to 17.6% in 2017 and 26.5% in 2018 (P < 0.001); the prescription rates of metformin, sulfonylurea, insulin, and dipeptidyl peptidase‐4 inhibitors did not change significantly over time. The prescription rates of metformin and SGLT2i were significantly higher in patients managed by cardiologists than non‐cardiologists (in 2018, 71.1% vs. 44.2% for metformin, 45.4% vs. 9.9% for SGLT2i, both P < 0.001). During the study period, annualized event rates of cardiovascular death or first unplanned HF hospitalization were 19.0 per 100 patient‐years. After a multivariate analysis, prescriptions of metformin {odds ratio (OR): 0.49 [95% confidence interval (CI) 0.27–0.51], P < 0.001} and SGLT2i [OR: 0.52 (95% CI 0.28–0.98), P = 0.042] were independently associated with lower annualized event rates of cardiovascular death or unplanned HF hospitalization. Conclusions Prescription patterns of diabetes medications in diabetics with HFrEF were diverse among different specialists. Prescriptions of metformin and SGLT2i were associated with favourable clinical outcomes. Our finding indicates the importance of awareness of beneficial effect of different classes of diabetes medications and collaboration between specialists in the management of diabetic HFrEF patients.
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Affiliation(s)
- Hung-Yu Chang
- Heart Center, Cheng Hsin General Hospital, No. 45, Cheng-Hsin Street, 112 Beitou, Taipei, Taiwan.,Faculty of Medicine, School of Medicine, National Yang Ming University, Taipei, Taiwan
| | - Yu-Wen Su
- Faculty of Medicine, School of Medicine, National Yang Ming University, Taipei, Taiwan.,Division of Endocrinology & Metabolism, Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - An-Ning Feng
- Heart Center, Cheng Hsin General Hospital, No. 45, Cheng-Hsin Street, 112 Beitou, Taipei, Taiwan.,Faculty of Medicine, School of Medicine, National Yang Ming University, Taipei, Taiwan
| | - Man-Cai Fong
- Heart Center, Cheng Hsin General Hospital, No. 45, Cheng-Hsin Street, 112 Beitou, Taipei, Taiwan.,National Defense Medical Center, Taipei, Taiwan
| | - Kuan-Chih Huang
- Heart Center, Cheng Hsin General Hospital, No. 45, Cheng-Hsin Street, 112 Beitou, Taipei, Taiwan
| | - Eric Chong
- Division of Cardiology, Farrer Park Hospital, Singapore, Singapore
| | - Kuan-Chun Chen
- Heart Center, Cheng Hsin General Hospital, No. 45, Cheng-Hsin Street, 112 Beitou, Taipei, Taiwan.,National Defense Medical Center, Taipei, Taiwan.,Institute of Emergency and Critical Care Medicine, National Yang Ming University, Taipei, Taiwan
| | - Wei-Hsian Yin
- Heart Center, Cheng Hsin General Hospital, No. 45, Cheng-Hsin Street, 112 Beitou, Taipei, Taiwan.,Faculty of Medicine, School of Medicine, National Yang Ming University, Taipei, Taiwan
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17
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Bukhari AAS, Zhang X, Li M, Zhao A, Dong H, Liang X. Cofilin participates in regulating alpha-epithelial sodium channel by interaction with 14-3-3 isoforms. J Biomed Res 2020; 34:351-360. [PMID: 32981895 PMCID: PMC7540242 DOI: 10.7555/jbr.34.20190155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Renal epithelial sodium channel (ENaC) plays a crucial role in maintaining homeostasis and sodium absorption. While insulin participates in controlling sodium transport across the renal epithelium, the underlying molecular mechanism remain unclear. In this study, we found that insulin increased the expression and function of alpha-epithelial sodium channel (α-ENaC) as well as phosphorylation of cofilin, a family of actin-binding proteins which disassembles actin filaments, in mouse cortical collecting duct (mpkCCDc14) cells. The wild-type (WT) cofilin and its constitutively phosphorylated form (S3D), but not its constitutively non-phosphorylable form (S3A), contributed to the elevated expression on α-ENaC. Overexpression of 14-3-3ε, β, or γ increased the expression of α-ENaC and cofilin phosphorylation, which was blunted by knockdown of 14-3-3ε, β, or γ. Moreover, it was found that insulin increased the interaction between cofilin and 14-3-3 isoforms, which indicated relevance of 14-3-3 isoforms with cofilin. Furthermore, LIMK1/SSH1 pathway was involved in regulation of cofilin and α-ENaC expression by insulin. The results from this work indicate that cofilin participates in the regulation of α-ENaC by interaction with 14-3-3 isoforms.
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Affiliation(s)
| | | | | | | | | | - Xiubin Liang
- Department of Pathophysiology;Department of Nephrology, the Affiliated Sir Run Run Hospital of Nanjing Medical University, Nanjing, Jiangsu 211166, China
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18
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Wang B, Cai W, Ai D, Zhang X, Yao L. The Role of Deubiquitinases in Vascular Diseases. J Cardiovasc Transl Res 2019; 13:131-141. [DOI: 10.1007/s12265-019-09909-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 08/21/2019] [Indexed: 12/15/2022]
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19
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Fan P, Lu CX, Yang KQ, Lu PP, Hao SF, Luo F, Zhang HM, Song L, Wu HY, Cai J, Zhang X, Zhou XL. Truncated Epithelial Sodium Channel β Subunit Responsible for Liddle Syndrome in a Chinese Family. Kidney Blood Press Res 2019; 44:942-949. [DOI: 10.1159/000500919] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 05/12/2019] [Indexed: 11/19/2022] Open
Abstract
Background/Aims: Liddle syndrome (LS) is a rare autosomal dominant disease caused by mutations in genes coding for epithelial sodium channel (ENaC) subunits. The aim of this study was to identify the mutation responsible for the LS in an extended Chinese family. Methods: DNA samples from the proband with early-onset, treatment-resistant hypertension, and hypokalemia and 19 additional relatives were all sequenced for mutations in exon 13 of the β-ENaC and γ-ENaC genes, using amplification by polymerase chain reaction and direct DNA sequencing. Results: Genetic testing of exon 13 of SCNN1B revealed duplication of guanine into a string of 3 guanines located at codon 602. This frameshift mutation is predicted to generate a premature stop codon at position 607, resulting in truncated β-ENaC lacking the remaining 34 amino acids, including the crucial PY motif. Among a total of 9 participants with the identical mutation, different phenotypes were identified. Tailored treatment with amiloride was safe and effective in alleviating disease symptoms in LS. No mutation of SCNN1G was identified in any of the examined participants. Conclusions: We report here a family affected by LS harboring a frameshift mutation (c.1806dupG) with a premature stop codon deleting the PY motif of β-ENaC. Our study demonstrates that the earlier LS patients are diagnosed by genetic testing and treated with tailored medication, the greater the likelihood of preventing or minimizing complications in the vasculature and target organs.
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20
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Sudo M, Sakamaki Y, Hosojima M, Yamamoto S, Ito Y, Imai N, Kaneko Y, Goto S, Li CP, Shimizu A, Narita I. Cryofibrinogen-associated glomerulonephritis diagnosed by mass spectrometry and immunoelectron microscopy. HUMAN PATHOLOGY: CASE REPORTS 2019. [DOI: 10.1016/j.ehpc.2018.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Asleh R, Sheikh-Ahmad M, Briasoulis A, Kushwaha SS. The influence of anti-hyperglycemic drug therapy on cardiovascular and heart failure outcomes in patients with type 2 diabetes mellitus. Heart Fail Rev 2019; 23:445-459. [PMID: 29270818 DOI: 10.1007/s10741-017-9666-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Patients with type 2 diabetes mellitus (DM) are at a substantially increased risk of heart failure (HF) and HF mortality. Despite the lack of evidence that tight glycemic control reduces the incidence of cardiovascular (CV) events, a growing body of evidence suggests that the choice of glucose-lowering agents may influence outcomes including HF. Thiazolidinediones are associated with a significant risk of HF. For metformin, sulphonylureas and insulin, little data is available to indicate the impact on HF. The glucagon-like peptide-1 (GLP-1) agonists, liraglutide and semaglutide, have been shown to reduce major CV events, but did not affect rates of hospitalization for HF. Clinical trials have demonstrated diverse effects of Dipeptidyl peptidase-4 (DPP-4) inhibitors on HF; saxagliptin showed an increased risk of HF admissions, alogliptin was associated with higher rates of new HF admissions, while sitagliptin had a neutral effect. The sodium-glucose cotransporter 2 (SGLT2) inhibitors, empagliflozin and canagliflozin, have been recently shown to reduce the incidence of HF and cardiovascular mortality in patients with and without a history of HF. This review will summarize key findings of the impact of glucose-lowering agents on CV safety and HF-associated outcomes, present available data on the underlying mechanisms for the benefits of the SGLT2 inhibitors on HF, and discuss strategies to improve outcomes in patients with DM and high CV risk.
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Affiliation(s)
- Rabea Asleh
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First St. SW, Gonda 5 S, Rochester, MN, 55905, USA.
| | | | - Alexandros Briasoulis
- Department of Cardiovascular Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
| | - Sudhir S Kushwaha
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First St. SW, Gonda 5 S, Rochester, MN, 55905, USA
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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
Liddle syndrome is an inherited form of low-renin hypertension, transmitted with an autosomal dominant pattern. The molecular basis of Liddle syndrome resides in germline mutations of the SCNN1A, SCNN1B and SCNN1G genes, encoding the α, β, and γ-subunits of the epithelial Na+ channel (ENaC), respectively. To date, 31 different causative mutations have been reported in 72 families from four continents. The majority of the substitutions cause an increased expression of the channel at the distal nephron apical membrane, with subsequent enhanced renal sodium reabsorption. The most common clinical presentation of the disease is early onset hypertension, hypokalemia, metabolic alkalosis, suppressed plasma renin activity and low plasma aldosterone. Consequently, treatment of Liddle syndrome is based on the administration of ENaC blockers, amiloride and triamterene. Herein, we discuss the genetic basis, clinical presentation, diagnosis and treatment of Liddle syndrome. Finally, we report a new case in an Italian family, caused by a SCNN1B p.Pro618Leu substitution.
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24
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Loh SY, Giribabu N, Salleh N. Changes in plasma aldosterone and electrolytes levels, kidney epithelial sodium channel (ENaC) and blood pressure in normotensive WKY and hypertensive SHR rats following gonadectomy and chronic testosterone treatment. Steroids 2017; 128:128-135. [PMID: 28954214 DOI: 10.1016/j.steroids.2017.09.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 09/14/2017] [Accepted: 09/20/2017] [Indexed: 12/17/2022]
Abstract
UNLABELLED We hypothesized that testosterone-induced increase in blood pressure involve changes in aldosterone levels and expression of epithelial sodium channel (ENaC) in the kidneys. METHODS Ovariectomized female normotensive Wistar Kyoto (WKY) and Spontaneous hypertensive (SHR) rats were given six weeks treatment with testosterone via subcutaneous silastic implant. The rats were anesthetized and mean arterial pressure (MAP) was measured via direct cannulation of the carotid artery. Animals were sacrificed and kidneys were removed and subjected for α, β and γ-ENaC protein and mRNA expression analyses by Western blotting and Real-time polymerase chain reaction (qPCR), respectively. Distributions of α, β and γ-ENaC proteins in kidneys were observed by immunofluorescence. Plasma testosterone, aldosterone, electrolytes, osmolality, urea and creatinine levels were determined by biochemical assays. Analysis were also performed in non-testosterone treated orchidectomized and sham-operated male WKY and SHR rats. RESULTS Treatment of ovariectomized female WKY and SHR rats with testosterone causes increased in MAP but decreased in plasma aldosterone, sodium (Na+), osmolality and expression and distribution of α, β and γ-ENaC subunits in the kidneys. Orchidectomy decreased the MAP but increased plasma aldosterone, Na+, osmolality and α, β and γ-ENaC expression and distribution in the kidneys of male WKY and SHR rats. CONCLUSIONS Decreased in plasma aldosterone, Na+ and ENaC levels in kidneys under testosterone influence indicated that testosterone-induced increased in MAP were not due to increased plasma aldosterone and ENaC levels in kidneys, and thus the testosterone effect on MAP likely involve other mechanisms.
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Affiliation(s)
- Su Yi Loh
- Department of Physiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Nelli Giribabu
- Department of Physiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Naguib Salleh
- Department of Physiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
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Samson R, Qi A, Jaiswal A, Le Jemtel TH, Oparil S. Obesity-Associated Hypertension: the Upcoming Phenotype in African-American Women. Curr Hypertens Rep 2017; 19:41. [DOI: 10.1007/s11906-017-0738-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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26
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Actions of Quercetin, a Polyphenol, on Blood Pressure. Molecules 2017; 22:molecules22020209. [PMID: 28146071 PMCID: PMC6155806 DOI: 10.3390/molecules22020209] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 12/20/2022] Open
Abstract
Disorder of blood pressure control causes serious diseases in the cardiovascular system. This review focuses on the anti-hypertensive action of quercetin, a flavonoid, which is one of the polyphenols characterized as the compounds containing large multiples of phenol structural units, by varying the values of various blood pressure regulatory factors, such as vascular compliance, peripheral vascular resistance, and total blood volume via anti-inflammatory and anti-oxidant actions. In addition to the anti-inflammatory and anti-oxidant actions of quercetin, we especially describe a novel mechanism of quercetin’s action on the cytosolic Cl− concentration ([Cl−]c) and novel roles of the cytosolic Cl− i.e., (1) quercetin elevates [Cl−]c by activating Na+-K+-2Cl− cotransporter 1 (NKCC1) in renal epithelial cells contributing to Na+ reabsorption via the epithelial Na+ channel (ENaC); (2) the quercetin-induced elevation of [Cl−]c in renal epithelial cells diminishes expression of ENaC leading to a decrease in renal Na+ reabsorption; and (3) this reduction of ENaC-mediated Na+ reabsorption in renal epithelial cells drops volume-dependent elevated blood pressure. In this review, we introduce novel, unique mechanisms of quercetin’s anti-hypertensive action via activation of NKCC1 in detail.
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Habibi J, Aroor AR, Sowers JR, Jia G, Hayden MR, Garro M, Barron B, Mayoux E, Rector RS, Whaley-Connell A, DeMarco VG. Sodium glucose transporter 2 (SGLT2) inhibition with empagliflozin improves cardiac diastolic function in a female rodent model of diabetes. Cardiovasc Diabetol 2017; 16:9. [PMID: 28086951 PMCID: PMC5237274 DOI: 10.1186/s12933-016-0489-z] [Citation(s) in RCA: 183] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 12/25/2016] [Indexed: 01/08/2023] Open
Abstract
Obese and diabetic individuals are at increased risk for impairments in diastolic relaxation and heart failure with preserved ejection fraction. The impairments in diastolic relaxation are especially pronounced in obese and diabetic women and predict future cardiovascular disease (CVD) events in this population. Recent clinical data suggest sodium glucose transporter-2 (SGLT2) inhibition reduces CVD events in diabetic individuals, but the mechanisms of this CVD protection are unknown. To determine whether targeting SGLT2 improves diastolic relaxation, we utilized empagliflozin (EMPA) in female db/db mice. Eleven week old female db/db mice were fed normal mouse chow, with or without EMPA, for 5 weeks. Blood pressure (BP), HbA1c and fasting glucose were significantly increased in untreated db/db mice (DbC) (P < 0.01). EMPA treatment (DbE) improved glycemic indices (P < 0.05), but not BP (P > 0.05). At baseline, DbC and DbE had already established impaired diastolic relaxation as indicated by impaired septal wall motion (>tissue Doppler derived E'/A' ratio) and increased left ventricular (LV) filling pressure (<E/E' ratio). Although these abnormalities persisted throughout the study period in DbC, diastolic function improved with EMPA treatment. In DbC, myocardial fibrosis was accompanied by increased expression of profibrotic/prohypertrophic proteins, serum/glucocorticoid regulated kinase 1 (SGK1) and the epithelial sodium channel (ENaC), and the development of these abnormalities were reduced with EMPA. DbC exhibited eccentric LV hypertrophy that was slightly improved by EMPA, indicated by a reduction in cardiomyocyte cross sectional area. In summary, EMPA improved glycemic indices along with diastolic relaxation, as well as SGK1/ENaC profibrosis signaling and associated interstitial fibrosis, all of which occurred in the absence of any changes in BP.
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Affiliation(s)
- Javad Habibi
- Department of Medicine, Division of Endocrinology, Diabetes and Cardiovascular Center, University of Missouri, School of Medicine, Columbia, USA.,Research Service, Harry S. Truman Memorial Veterans Hospital, Columbia, MO, USA
| | - Annayya R Aroor
- Department of Medicine, Division of Endocrinology, Diabetes and Cardiovascular Center, University of Missouri, School of Medicine, Columbia, USA.,Research Service, Harry S. Truman Memorial Veterans Hospital, Columbia, MO, USA
| | - James R Sowers
- Department of Medicine, Division of Endocrinology, Diabetes and Cardiovascular Center, University of Missouri, School of Medicine, Columbia, USA.,Department of Medical Pharmacology and Physiology, University of Missouri, School of Medicine, Columbia, USA.,Research Service, Harry S. Truman Memorial Veterans Hospital, Columbia, MO, USA.,The Dalton Cardiovascular Research Center, Columbia, MO, USA
| | - Guanghong Jia
- Department of Medicine, Division of Endocrinology, Diabetes and Cardiovascular Center, University of Missouri, School of Medicine, Columbia, USA.,Research Service, Harry S. Truman Memorial Veterans Hospital, Columbia, MO, USA
| | - Melvin R Hayden
- Department of Medicine, Division of Endocrinology, Diabetes and Cardiovascular Center, University of Missouri, School of Medicine, Columbia, USA
| | - Mona Garro
- Department of Medicine, Division of Endocrinology, Diabetes and Cardiovascular Center, University of Missouri, School of Medicine, Columbia, USA.,Research Service, Harry S. Truman Memorial Veterans Hospital, Columbia, MO, USA
| | - Brady Barron
- Department of Medicine, Division of Endocrinology, Diabetes and Cardiovascular Center, University of Missouri, School of Medicine, Columbia, USA.,Research Service, Harry S. Truman Memorial Veterans Hospital, Columbia, MO, USA
| | - Eric Mayoux
- Department of Cardiometabolic Diseases Research, Boehringer-Ingelheim, Biberach, Germany
| | - R Scott Rector
- Research Service, Harry S. Truman Memorial Veterans Hospital, Columbia, MO, USA.,Departments of Medicine-Gastroenterology and Hepatology and Nutrition and Exercise Physiology, University of Missouri, Columbia, MO, USA
| | - Adam Whaley-Connell
- Department of Medicine, Division of Endocrinology, Diabetes and Cardiovascular Center, University of Missouri, School of Medicine, Columbia, USA.,Division of Nephrology, University of Missouri, School of Medicine, Columbia, USA.,Research Service, Harry S. Truman Memorial Veterans Hospital, Columbia, MO, USA
| | - Vincent G DeMarco
- Department of Medicine, Division of Endocrinology, Diabetes and Cardiovascular Center, University of Missouri, School of Medicine, Columbia, USA. .,Department of Medical Pharmacology and Physiology, University of Missouri, School of Medicine, Columbia, USA. .,Research Service, Harry S. Truman Memorial Veterans Hospital, Columbia, MO, USA.
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Thiazide diuretics and the risk of osteoporotic fractures in hypertensive patients. Results from the Swedish Primary Care Cardiovascular Database. J Hypertens 2017; 35:188-197. [DOI: 10.1097/hjh.0000000000001124] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Yang W, Zhu Z, Wang J, Ye W, Ding Y. Evaluation of the relationship between T663A polymorphism in the alpha-epithelial sodium channel gene and essential hypertension. Saudi Med J 2016; 36:1039-45. [PMID: 26318459 PMCID: PMC4613626 DOI: 10.15537/smj.2015.9.11822] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Objectives: To evaluate the relationship between alpha epithelial sodium channel (alpha-ENaC) T663A polymorphism and the risk of essential hypertension. Methods: This meta-analysis was conducted between November 2014 and February 2015 in Shanghai Medical Instrumentation College, Shanghai, China. We collected all published available case-control data (N=12) identified through PubMed, Web of Science, Scopus, and Chinese National Knowledge Infrastructure (CNKI) up to December 2014. The pooled odds ratio (OR) with 95% confidence interval (CI) was calculated using the fixed- or random-effect model. Results: Although subgroup analysis showed that alpha-ENaC T663A polymorphism was associated with essential hypertension in North American individuals (OR=1.55, 95% CI=1.22-1.98, p=0.0003), our meta-analysis results did not confirm such association overall (OR=1.03, 95% CI=0.92-1.15, p=0.62). The lack of association was further confirmed by the non-superiority test (p<0.0001). Conclusion: Alpha-ENaC T663A polymorphism might not be a risk factor for essential hypertension.
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Affiliation(s)
- Wenchao Yang
- School of Pharmacy, Shanghai University of Medicine & Health Sciences, Shanghai, China. E-mail.
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Abstract
During the past 20 years, the studies on genetics or pharmacogenomics of primary hypertension provided interesting results supporting the role of genetics, but no actionable finding ready to be translated into personalized medicine. Two types of approaches have been applied: a "hypothesis-driven" approach on the candidate genes, coding for proteins involved in the biochemical machinery underlying the regulation of BP, and an "unbiased hypothesis-free" approach with GWAS, based on the randomness principles of frequentist statistics. During the past 10-15 years, the application of the latter has overtaken the application of the former leading to an enlargement of the number of previously unknown candidate loci or genes but without any actionable result for the therapy of hypertension. In the present review, we summarize the results of our hypothesis-driven approach based on studies carried out in rats with genetic hypertension and in humans with essential hypertension at the pre-hypertensive and early hypertensive stages. These studies led to the identification of mutant adducin and endogenous ouabain as candidate genetic-molecular mechanisms in both species. Rostafuroxin has been developed for its ability to selectively correct Na(+) pump abnormalities sustained by the two abovementioned mechanisms and to selectively reduce BP in rats and in humans carrying the gene variants underlying the mutant adducin and endogenous ouabain (EO) effects. A clinical trial is ongoing to substantiate these findings. Future studies should apply both the candidate gene and GWAS approaches to fully exploit the potential of genetics in optimizing the personalized therapy.
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Loh SY, Giribabu N, Salleh N. Sub-chronic testosterone treatment increases the levels of epithelial sodium channel (ENaC)-α, β and γ in the kidney of orchidectomized adult male Sprague-Dawley rats. PeerJ 2016; 4:e2145. [PMID: 27413634 PMCID: PMC4933084 DOI: 10.7717/peerj.2145] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 05/26/2016] [Indexed: 11/20/2022] Open
Abstract
Testosterone has been reported to cause blood pressure to increase. However mechanisms that underlie the effect of this hormone on this physiological parameter are currently not well understood. The aims of this study were to investigate effects of testosterone on expression of α, β and γ-epithelial sodium channel (ENaC) proteins and messenger RNAs (mRNAs) in kidneys, the channel known to be involved in Na+ reabsorption, which subsequently can affect the blood pressure. Methods. Adult male Sprague–Dawley (SD) rats were orchidectomized fourteen days prior to receiving seven days treatment with testosterone propionate (125 µg/kg/day or 250 µg/kg/day) with or without flutamide (androgen receptor blocker) or finasteride (5α-reductase inhibitor). Following sacrifice, the kidneys were removed and were subjected for α, β and γ-ENaC protein and mRNA expression analyses by Western blotting and Real-time PCR (qPCR) respectively. The distribution of α, β and γ-ENaC proteins in kidneys were observed by immunofluorescence. Results. The α, β and γ-ENaC proteins and mRNA levels in kidneys were enhanced in rats which received testosterone-only treatment. In these rats, α, β and γ-ENaC proteins were distributed in the distal tubules and collecting ducts of the nephrons. Co-treatment with flutamide or finasteride resulted in the levels of α, β and γ-ENaC proteins and mRNAs in kidneys to decrease. In conclusions, increases in α, β and γ-ENaC protein and mRNA levels in kidneys mainly in the distal tubules and collecting ducts under testosterone influence might lead to enhance Na+ reabsorption which subsequently might cause an increase in blood pressure.
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Affiliation(s)
- Su Yi Loh
- Department of Physiology, University of Malaya, Kuala Lumpur, Malaysia
| | - Nelli Giribabu
- Department of Physiology, University of Malaya, Kuala Lumpur, Malaysia
| | - Naguib Salleh
- Department of Physiology, University of Malaya, Kuala Lumpur, Malaysia
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Heart Failure Considerations of Antihyperglycemic Medications for Type 2 Diabetes. Circ Res 2016; 118:1830-43. [DOI: 10.1161/circresaha.116.306924] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 03/30/2016] [Indexed: 12/21/2022]
Abstract
Prevalent and incident heart failure (HF) is increased in people with type 2 diabetes mellitus, with risk directly associated with the severity of hyperglycemia. Furthermore, in patients with type 2 diabetes mellitus, mortality is increased ≈10-fold in patients with versus without HF. Reducing HF with antihyperglycemic therapies, however, has been unsuccessful until recently. In fact, HF as an important outcome in patients with type 2 diabetes mellitus seems to be heterogeneously modulated by antihyperglycemic medications, as evidenced by results from cardiovascular outcome trials (CVOTs) and large observational cohort studies. Appropriately powered and executed CVOTs are necessary to truly evaluate cardiovascular safety and efficacy of new antihyperglycemic medications, as reflected by the guidance of the US Food and Drug Administration and other regulatory agencies since 2008. In light of the best available evidence at present, metformin and the sodium-glucose-co-transporter 2-inhibitor empagliflozin seem to be especially advantageous with regard to HF effects, with their use associated with reduced HF events and improved mortality. Acarbose, the dipeptidyl-peptidase 4-inhibitor sitagliptin, the glucagon-like peptide 1-receptor agonist lixisenatide based on presently available CVOT results comprise reasonable additional options, as significant harm in terms of HF has been excluded for those drugs. Additions to this list are anticipated pending results of ongoing CVOTs. Although no HF harm was seen in CVOTs for insulin or sulfonylureas, they should be used only with caution in patients with HF, given their established high risk for hypoglycemia and some uncertainties on their safety in patients with HF derived from epidemiological observations. Pioglitazone is contraindicated in patients with HF>New York Heart Association I, despite some benefits suggested by CVOT subanalyses.
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Abstract
Heart disease is a leading cause of death in the United States, and hypertension is a predominant risk factor. Thus, effective blood pressure control is important to prevent adverse sequelae of hypertension, including heart failure, coronary artery disease, atrial fibrillation, and ischemic stroke. Over half of Americans have uncontrolled blood pressure, which may in part be explained by interpatient variability in drug response secondary to genetic polymorphism. As such, pharmacogenetic testing may be a supplementary tool to guide treatment. This review highlights the pharmacogenetics of antihypertensive response and response to drugs that treat adverse hypertension-related sequelae, particularly coronary artery disease and atrial fibrillation. While pharmacogenetic evidence may be more robust for the latter with respect to clinical implementation, there is increasing evidence of genetic variants that may help predict antihypertensive response. However, additional research and validation are needed before clinical implementation guidelines for antihypertensive therapy can become a reality.
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Abstract
Resistant hypertension (RHTN), defined as an uncontrolled blood pressure despite the use of multiple antihypertensive medications, is an increasing clinical problem associated with increased cardiovascular (CV) risk, including stroke and target organ damage. Genetic variability in blood pressure (BP)-regulating genes and pathways may, in part, account for the variability in BP response to antihypertensive agents, when taken alone or in combination, and may contribute to the RHTN phenotype. Pharmacogenomics focuses on the identification of genetic factors responsible for inter-individual variability in drug response. Expanding pharmacogenomics research to include patients with RHTN taking multiple BP-lowering medications may identify genetic markers associated with RHTN. To date, the available evidence surrounding pharmacogenomics in RHTN is limited and primarily focused on candidate genes. In this review, we summarize the most current data in RHTN pharmacogenomics and offer some recommendations on how to advance the field.
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Affiliation(s)
- Nihal El Rouby
- Department of Pharmacotherapy and Translational Research, University of Florida, PO Box 100486, 1600 SW Archer Road, Gainesville, FL 32610-0486, USA
| | - Rhonda M. Cooper-DeHoff
- Department of Pharmacotherapy and Translational Research, University of Florida, PO Box 100486, 1600 SW Archer Road, Gainesville, FL 32610-0486, USA
- Division of Cardiovascular Medicine, Colleges of Pharmacy and Medicine, University of Florida, PO Box 100486, 1600 SW Archer Road, Gainesville, FL 32610-0486, USA
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Kortenoeven MLA, Pedersen NB, Rosenbaek LL, Fenton RA. Vasopressin regulation of sodium transport in the distal nephron and collecting duct. Am J Physiol Renal Physiol 2015; 309:F280-99. [DOI: 10.1152/ajprenal.00093.2015] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 05/27/2015] [Indexed: 12/22/2022] Open
Abstract
Arginine vasopressin (AVP) is released from the posterior pituitary gland during states of hyperosmolality or hypovolemia. AVP is a peptide hormone, with antidiuretic and antinatriuretic properties. It allows the kidneys to increase body water retention predominantly by increasing the cell surface expression of aquaporin water channels in the collecting duct alongside increasing the osmotic driving forces for water reabsorption. The antinatriuretic effects of AVP are mediated by the regulation of sodium transport throughout the distal nephron, from the thick ascending limb through to the collecting duct, which in turn partially facilitates osmotic movement of water. In this review, we will discuss the regulatory role of AVP in sodium transport and summarize the effects of AVP on various molecular targets, including the sodium-potassium-chloride cotransporter NKCC2, the thiazide-sensitive sodium-chloride cotransporter NCC, and the epithelial sodium channel ENaC.
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Affiliation(s)
- M. L. A. Kortenoeven
- Department of Biomedicine and Center for Interactions of Proteins in Epithelial Transport (InterPrET), Aarhus University, Aarhus, Denmark
| | - N. B. Pedersen
- Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark; and
| | - L. L. Rosenbaek
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - R. A. Fenton
- Department of Biomedicine and Center for Interactions of Proteins in Epithelial Transport (InterPrET), Aarhus University, Aarhus, Denmark
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Shen Y, Xu W, You H, Su D, Xing J, Li M, Li L, Liang X. FoxO1 inhibits transcription and membrane trafficking of epithelial Na+ channel. J Cell Sci 2015; 128:3621-30. [PMID: 26272921 DOI: 10.1242/jcs.171876] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 08/02/2015] [Indexed: 01/06/2023] Open
Abstract
The epithelial Na(+) channel (ENaC), regulated by insulin, is of fundamental importance in the control of Na(+) reabsorption in the distal nephron. The potential role of Forkhead box O1 (FoxO1), downstream of insulin signaling, in the regulation of ENaC remains to be investigated. Here, we found that the overexpression of a constitutively active form of FoxO1 (ADA-FoxO1) suppressed the mRNA level of the ENaC α subunit (α-ENaC; also known as SCCN1A) and the apical density of ENaC in mouse cortical collecting duct (mCCD) cells. Conversely, knockdown of FoxO1 increased the apical membrane levels of α-ENaC and Na(+) transport under basal conditions. Insulin elevated α-ENaC expression and induced FoxO1 phosphorylation; however, the increase in α-ENaC and phosphorylated FoxO1 expression observed with insulin treatment was blunted ∼ 60% in cells expressing ADA-FoxO1. Moreover, insulin induced the interaction between phosphorylated FoxO1 and 14-3-3ε, indicating that FoxO1 phosphorylation promotes ENaC membrane trafficking by binding to 14-3-3ε. FoxO1 also suppressed activity of the α-ENaC promoter, and the putative FoxO1 target site is located in the -500 to -200 nt region of the α-ENaC promoter. These findings indicate that FoxO1 is a key negative regulatory factor in the insulin-dependent control of ENaC expression and forward trafficking in mCCD epithelia.
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Affiliation(s)
- Yachen Shen
- Center of Metabolic Disease Research, Nanjing Medical University, 210029 Nanjing, Jiangsu Province, China
| | - Weifeng Xu
- Center of Metabolic Disease Research, Nanjing Medical University, 210029 Nanjing, Jiangsu Province, China
| | - Hui You
- Center of Metabolic Disease Research, Nanjing Medical University, 210029 Nanjing, Jiangsu Province, China
| | - Dongming Su
- Department of Pathology, Nanjing Medical University, 210029 Nanjing, Jiangsu Province, China State Key Laboratory of Reproductive Medicine, Nanjing Medical University, 210029 Nanjing, Jiangsu Province, China
| | - Jing Xing
- Center of Metabolic Disease Research, Nanjing Medical University, 210029 Nanjing, Jiangsu Province, China
| | - Min Li
- Center of Metabolic Disease Research, Nanjing Medical University, 210029 Nanjing, Jiangsu Province, China
| | - Lei Li
- Center of Metabolic Disease Research, Nanjing Medical University, 210029 Nanjing, Jiangsu Province, China
| | - Xiubin Liang
- Center of Metabolic Disease Research, Nanjing Medical University, 210029 Nanjing, Jiangsu Province, China State Key Laboratory of Reproductive Medicine, Nanjing Medical University, 210029 Nanjing, Jiangsu Province, China
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Zhang Y, Sun Y, Ding G, Huang S, Zhang A, Jia Z. Inhibition of Mitochondrial Complex-1 Prevents the Downregulation of NKCC2 and ENaCα in Obstructive Kidney Disease. Sci Rep 2015. [PMID: 26207612 PMCID: PMC4513566 DOI: 10.1038/srep12480] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Ureteral obstruction with subsequent hydronephrosis is a common clinical complication. Downregulation of renal sodium transporters in obstructed kidneys could contribute to impaired urinary concentrating capability and salt waste following the release of a ureteral obstruction. The current study was undertaken to investigate the role of mitochondrial complex-1 inhibition in modulating sodium transporters in obstructive kidney disease. Following unilateral ureteral obstruction (UUO) for 7 days, a global reduction of sodium transporters, including NHE3, α-Na-K-ATPase, NCC, NKCC2, p-NKCC2, ENaCα, and ENaCγ, was observed, as determined via qRT-PCR and/or Western blotting. Interestingly, inhibition of mitochondrial complex-1 by rotenone markedly reversed the downregulation of NKCC2, p-NKCC2, and ENaCα. In contrast, other sodium transporters were not affected by rotenone. To study the potential mechanisms involved in mediating the effects of rotenone on sodium transporters, we examined a number of known sodium modulators, including PGE2, ET1, Ang II, natriuretic peptides (ANP, BNP, and CNP), and nitric oxide synthases (iNOS, nNOS, and eNOS). Importantly, among these modulators, only BNP and iNOS were significantly reduced by rotenone treatment. Collectively, these findings demonstrated a substantial role of mitochondrial dysfunction in mediating the downregulation of NKCC2 and ENaCα in obstructive kidney disease, possibly via iNOS-derived nitric oxide and BNP.
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Affiliation(s)
- Yue Zhang
- 1] Department of Nephrology, Nanjing Children's Hospital, Affiliated with Nanjing Medical University, Nanjing 210008, China [2] Institute of Pediatrics, Nanjing Medical University, Nanjing, China [3] Nanjing Key Laboratory of Pediatrics, Nanjing Children Hospital, Affiliated with Nanjing Medical University, Nanjing 210008, China
| | - Ying Sun
- 1] Department of Nephrology, Nanjing Children's Hospital, Affiliated with Nanjing Medical University, Nanjing 210008, China [2] Institute of Pediatrics, Nanjing Medical University, Nanjing, China [3] Nanjing Key Laboratory of Pediatrics, Nanjing Children Hospital, Affiliated with Nanjing Medical University, Nanjing 210008, China
| | - Guixia Ding
- 1] Department of Nephrology, Nanjing Children's Hospital, Affiliated with Nanjing Medical University, Nanjing 210008, China [2] Institute of Pediatrics, Nanjing Medical University, Nanjing, China [3] Nanjing Key Laboratory of Pediatrics, Nanjing Children Hospital, Affiliated with Nanjing Medical University, Nanjing 210008, China
| | - Songming Huang
- 1] Department of Nephrology, Nanjing Children's Hospital, Affiliated with Nanjing Medical University, Nanjing 210008, China [2] Institute of Pediatrics, Nanjing Medical University, Nanjing, China [3] Nanjing Key Laboratory of Pediatrics, Nanjing Children Hospital, Affiliated with Nanjing Medical University, Nanjing 210008, China
| | - Aihua Zhang
- 1] Department of Nephrology, Nanjing Children's Hospital, Affiliated with Nanjing Medical University, Nanjing 210008, China [2] Institute of Pediatrics, Nanjing Medical University, Nanjing, China [3] Nanjing Key Laboratory of Pediatrics, Nanjing Children Hospital, Affiliated with Nanjing Medical University, Nanjing 210008, China
| | - Zhanjun Jia
- 1] Department of Nephrology, Nanjing Children's Hospital, Affiliated with Nanjing Medical University, Nanjing 210008, China [2] Institute of Pediatrics, Nanjing Medical University, Nanjing, China [3] Nanjing Key Laboratory of Pediatrics, Nanjing Children Hospital, Affiliated with Nanjing Medical University, Nanjing 210008, China
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Wang LP, Yang KQ, Jiang XJ, Wu HY, Zhang HM, Zou YB, Song L, Bian J, Hui RT, Liu YX, Zhou XL. Prevalence of Liddle Syndrome Among Young Hypertension Patients of Undetermined Cause in a Chinese Population. J Clin Hypertens (Greenwich) 2015; 17:902-7. [PMID: 26075967 DOI: 10.1111/jch.12598] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 04/14/2015] [Accepted: 04/19/2015] [Indexed: 11/28/2022]
Affiliation(s)
- Lin-Ping Wang
- Department of Cardiology; Fuwai Hospital; National Center for Cardiovascular Disease; Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing China
| | - Kun-Qi Yang
- Department of Cardiology; Fuwai Hospital; National Center for Cardiovascular Disease; Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing China
| | - Xiong-Jing Jiang
- Department of Cardiology; Fuwai Hospital; National Center for Cardiovascular Disease; Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing China
| | - Hai-Ying Wu
- Department of Cardiology; Fuwai Hospital; National Center for Cardiovascular Disease; Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing China
| | - Hui-Min Zhang
- Department of Cardiology; Fuwai Hospital; National Center for Cardiovascular Disease; Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing China
| | - Yu-Bao Zou
- Department of Cardiology; Fuwai Hospital; National Center for Cardiovascular Disease; Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing China
| | - Lei Song
- Department of Cardiology; Fuwai Hospital; National Center for Cardiovascular Disease; Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing China
| | - Jin Bian
- Department of Cardiology; Fuwai Hospital; National Center for Cardiovascular Disease; Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing China
| | - Ru-Tai Hui
- Department of Cardiology; Fuwai Hospital; National Center for Cardiovascular Disease; Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing China
- State Key Laboratory of Cardiovascular Disease; Sino-German Laboratory for Molecular Medicine; Fuwai Hospital; National Center for Cardiovascular Diseases; Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing China
| | - Ya-Xin Liu
- Department of Cardiology; Fuwai Hospital; National Center for Cardiovascular Disease; Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing China
| | - Xian-Liang Zhou
- Department of Cardiology; Fuwai Hospital; National Center for Cardiovascular Disease; Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing China
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Abstract
Individuals with diabetes are not only at high risk of developing heart failure but are also at increased risk of dying from it. Fortunately, antiheart failure therapies such as angiotensin-converting-enzyme inhibitors, β blockers and mineralocorticoid-receptor antagonists work similarly well in individuals with diabetes as in individuals without the disease. Response to intensive glycaemic control and the various classes of antihyperglycaemic agent therapy is substantially less well understood. Insulin, for example, induces sodium retention and thiazolidinediones increase the risk of heart failure. The need for new glucose-lowering drugs to show cardiovascular safety has led to the unexpected finding of an increase in the risk of admission to hospital for heart failure in patients treated with the dipeptidylpeptidase-4 (DPP4) inhibitor, saxagliptin, compared with placebo. Here we review the relation between glycaemic control and heart failure risk, focusing on the state of knowledge for the various types of antihyperglycaemic drugs that are used at present.
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Affiliation(s)
- Richard E Gilbert
- Division of Endocrinology, St Michael's Hospital, University of Toronto, On, Canada.
| | - Henry Krum
- Centre of Cardiovascular Research and Education in Therapeutics, Monash University, Melbourne, VIC, Australia
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ENaC in the Rabbit Lacrimal Gland and its Changes During Sjögren Syndrome and Pregnancy. Eye Contact Lens 2015; 41:297-303. [PMID: 25828511 DOI: 10.1097/icl.0000000000000123] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE Epithelial sodium channel (ENaC) plays a critical role in the control of Na(+) balance and the development and progression of exocrine gland pathologic condition. The aim of the present study was to investigate the presence of ENaC in the rabbit lacrimal gland (LG) and its potential changes during induced autoimmune dacryoadenitis (IAD) and pregnancy. METHODS Total messenger RNA (mRNA) of α, β, and γ subunits was extracted from whole LG, acinar cells, and ductal cells by laser capture microdissection (LCM) for real-time reverse-transcriptase polymerase chain reaction. Lacrimal glands were processed for Western blot and immunofluorescence. RESULTS Messenger RNA for both α and γ was expressed in whole LG lysates, whereas β was undetectable. In rabbits with IAD, the levels of mRNA for α and γ were 20.9% and 58.9% lower (P<0.05), whereas no significant changes were observed in term-pregnant rabbits (P=0.152). However, we were unable to detect mRNA of any subunit in LCM specimens of ductal cells because of their low levels. Western blot demonstrated bands for both α (90 kDa) and γ (85 kDa) but β was undetectable. In rabbits with IAD, densitometry analysis showed that expression of α decreased 22%, whereas γ decreased 26% (P<0.05). In pregnant rabbits, however, α expression was 31% lower, whereas γ expression was 34% lower (P<0.05). From immunofluorescence studies, all subunits were present in ductal cells, whereas virtually no immunoreactivity was detected in acini. No noticeable changes of their distribution pattern and intensity were found in rabbits with IAD or during pregnancy. CONCLUSIONS The present study demonstrated the presence of ENaC in the rabbit LG and its alterations in IAD and pregnancy, suggesting that ENaC may contribute to the pathogenesis of altered LG secretion and ocular surface symptoms in these animals.
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Gleason CE, Frindt G, Cheng CJ, Ng M, Kidwai A, Rashmi P, Lang F, Baum M, Palmer LG, Pearce D. mTORC2 regulates renal tubule sodium uptake by promoting ENaC activity. J Clin Invest 2014; 125:117-28. [PMID: 25415435 DOI: 10.1172/jci73935] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 10/23/2014] [Indexed: 12/17/2022] Open
Abstract
The epithelial Na+ channel (ENaC) is essential for Na+ homeostasis, and dysregulation of this channel underlies many forms of hypertension. Recent studies suggest that mTOR regulates phosphorylation and activation of serum/glucocorticoid regulated kinase 1 (SGK1), which is known to inhibit ENaC internalization and degradation; however, it is not clear whether mTOR contributes to the regulation of renal tubule ion transport. Here, we evaluated the effect of selective mTOR inhibitors on kidney tubule Na+ and K+ transport in WT and Sgk1-/- mice, as well as in isolated collecting tubules. We found that 2 structurally distinct competitive inhibitors (PP242 and AZD8055), both of which prevent all mTOR-dependent phosphorylation, including that of SGK1, caused substantial natriuresis, but not kaliuresis, in WT mice, which indicates that mTOR preferentially influences ENaC function. PP242 also substantially inhibited Na+ currents in isolated perfused cortical collecting tubules. Accordingly, patch clamp studies on cortical tubule apical membranes revealed that mTOR inhibition markedly reduces ENaC activity, but does not alter activity of K+ inwardly rectifying channels (ROMK channels). Together, these results demonstrate that mTOR regulates kidney tubule ion handling and suggest that mTOR regulates Na+ homeostasis through SGK1-dependent modulation of ENaC activity.
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Yang X, He J, Gu D, Hixson JE, Huang J, Rao DC, Shimmin LC, Chen J, Rice TK, Li J, Schwander K, Kelly TN. Associations of epithelial sodium channel genes with blood pressure changes and hypertension incidence: the GenSalt study. Am J Hypertens 2014; 27:1370-6. [PMID: 24735600 DOI: 10.1093/ajh/hpu060] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND We examined the associations of epithelial sodium channel (ENaC) genes with blood pressure (BP) changes and hypertension incidence in a longitudinal family study. METHODS A total of 2,755 Han Chinese participants of the Genetic Epidemiology Network of Salt Sensitivity (GenSalt) baseline examination were eligible for this study. The associations of 43 tag single nucleotide polymorphisms (SNPs) in ENaC genes with BP changes and hypertension incidence were assessed using mixed models to account for the correlations of repeated measures among individuals and within families. A genotype by time interaction term was used to model differences in longitudinal BP change according to genotype over time. Gene-based analyses were conducted using the truncated product method. The Bonferroni method was used to adjust for multiple testing in all analyses. RESULTS During an average of 7.4 years follow-up, systolic BP (SBP) and diastolic BP (DBP) increased, and approximately 33% of participants developed hypertension. SCNN1A SNP rs11064153 and SCNN1G SNP rs4401050 were significantly associated with longitudinal changes in SBP after adjustment for multiple testing (P interaction = 5.8×10(-4) and 0.001, respectively). Similar but nonsignificant trends were observed for the associations between both rs11064153 and rs4401050 and DBP changes (P interaction = 0.024 and 0.005, respectively) and between rs11604153 and hypertension incidence (P = 0.02). Gene-based analyses also supported the overall association of SCNN1G with longitudinal changes in SBP (P = 2.0×10(-4)). CONCLUSIONS Our findings indicated that SCNN1A and SCNN1G may contribute to BP changes over time in the Han Chinese population. Replication of these findings is warranted.
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Affiliation(s)
- Xueli Yang
- Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana; State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center of Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jiang He
- Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana; Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana
| | - Dongfeng Gu
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center of Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China;
| | - James E Hixson
- Department of Epidemiology, Human Genetics and Environmental Sciences, University of Texas School of Public Health, Houston, Texas
| | - Jianfeng Huang
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center of Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Dabeeru C Rao
- Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri
| | - Lawrence C Shimmin
- Department of Epidemiology, Human Genetics and Environmental Sciences, University of Texas School of Public Health, Houston, Texas
| | - Jichun Chen
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center of Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Treva K Rice
- Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri
| | - Jianxin Li
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center of Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Karen Schwander
- Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri
| | - Tanika N Kelly
- Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana
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Schönberger M, Althaus M, Fronius M, Clauss W, Trauner D. Controlling epithelial sodium channels with light using photoswitchable amilorides. Nat Chem 2014; 6:712-9. [PMID: 25054942 DOI: 10.1038/nchem.2004] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 06/12/2014] [Indexed: 11/09/2022]
Abstract
Amiloride is a widely used diuretic that blocks epithelial sodium channels (ENaCs). These heterotrimeric transmembrane proteins, assembled from β, γ and α or δ subunits, effectively control water transport across epithelia and sodium influx into non-epithelial cells. The functional role of δβγENaC in various organs, including the human brain, is still poorly understood and no pharmacological tools are available for the functional differentiation between α- and δ-containing ENaCs. Here we report several photoswitchable versions of amiloride. One compound, termed PA1, enables the optical control of ENaC channels, in particular the δβγ isoform, by switching between blue and green light, or by turning on and off blue light. PA1 was used to modify functionally δβγENaC in amphibian and mammalian cells. We also show that PA1 can be used to differentiate between δβγENaC and αβγENaC in a model for the human lung epithelium.
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Affiliation(s)
- Matthias Schönberger
- Department of Chemistry and Center for Integrated Protein Science, Ludwig Maximilians-Universität München, Butenandtstraße 5-13 (F4.086), 81377 Munich, Germany
| | - Mike Althaus
- Institute of Animal Physiology, Justus Liebig University Giessen, Heinrich-Buff-Ring 26, 35392 Giessen, Germany
| | - Martin Fronius
- 1] Institute of Animal Physiology, Justus Liebig University Giessen, Heinrich-Buff-Ring 26, 35392 Giessen, Germany [2] Department of Physiology, University of Otago, PO Box 913, Dunedin 9054, New Zealand
| | - Wolfgang Clauss
- Institute of Animal Physiology, Justus Liebig University Giessen, Heinrich-Buff-Ring 26, 35392 Giessen, Germany
| | - Dirk Trauner
- Department of Chemistry and Center for Integrated Protein Science, Ludwig Maximilians-Universität München, Butenandtstraße 5-13 (F4.086), 81377 Munich, Germany
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Laffer CL, Elijovich F, Eckert GJ, Tu W, Pratt JH, Brown NJ. Genetic variation in CYP4A11 and blood pressure response to mineralocorticoid receptor antagonism or ENaC inhibition: an exploratory pilot study in African Americans. JOURNAL OF THE AMERICAN SOCIETY OF HYPERTENSION : JASH 2014; 8:475-80. [PMID: 25064769 PMCID: PMC4115247 DOI: 10.1016/j.jash.2014.04.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 04/30/2014] [Accepted: 04/30/2014] [Indexed: 11/23/2022]
Abstract
An rs3890011 variant of CYP4A11, which is in linkage disequilibrium with the loss-of-function variant rs1126742, is associated with hypertension in humans. In mice, Cyp4a deficiency results in salt-sensitive hypertension through activation of ENaC. We tested the hypothesis that the rs3890011 variant is associated with blood pressure response to drugs acting via the ENaC pathway. African Americans with volume-dependent, resistant hypertension were randomized to treatment with placebo, spironolactone, amiloride, or combination. Blood pressure responses were analyzed by CYP4A11 genotypes. Rs3890011 (GG:GC:CC = 20:35:28) and rs1126742 (TT:TC:CC = 45:31:7) were in linkage disequilibrium (D' = 1, r = 0.561). Expected small number of rs1126742 CC homozygotes precluded analysis of the effect of this genotype on treatment responses. Spironolactone reduced blood pressure in rs3890011 GG and GC individuals, but not in CC homozygotes (P = .002), whereas amiloride reduced blood pressure similarly in all rs3890011 genotypes. The antihypertensive effects of spironolactone and amiloride were comparable in GG and GC participants, but only amiloride reduced pressure in CC homozygotes (-6.3 ± 7.3/-3.2 ± 4.0 vs. +6.8 ± 7.9/+4.8 ± 8.6 mm Hg, P < .01/<.05). The aldosterone response to spironolactone was also blunted in the CC genotype. In individuals homozygous for the CYP4A11 rs3890011 C allele, blood pressure is resistant to mineralocorticoid receptor antagonism, but sensitive to ENaC inhibition, consistent with ENaC activation. Studies in a larger population are needed to replicate these findings.
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Affiliation(s)
- Cheryl L Laffer
- The Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA.
| | - Fernando Elijovich
- The Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - George J Eckert
- The Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Wanzhu Tu
- The Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA; The Regenstrief Institute, Inc., Indianapolis, IN, USA
| | - J Howard Pratt
- The Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA; The Richard L Roudebush VA Medical Center, Indianapolis, IN, USA
| | - Nancy J Brown
- The Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA
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Wang Y, Liu Z, Hua Q, Chen Y, Cai Y, Liu R. Association of epithelial sodium channel β-subunit common polymorphism with essential hypertension families in a Chinese population. Cell Biochem Biophys 2014; 70:1277-82. [PMID: 24888492 DOI: 10.1007/s12013-014-0051-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The purpose of this study was to investigate whether common polymorphisms in the C-terminus of SCNN1B gene encoding the β-subunit of epithelial sodium channel are associated with essential hypertension (EH) in Chinese hypertensive families. A total of 433 subjects from 102 EH families were recruited. Biochemical and anthropometric indices and systematic screening of the C-terminus of SCNN1B were performed. Four single nucleotide polymorphisms (SNPs) were found. Homozygotes for the common A allele at rs3743966 had on average a 12.06 mmHg higher SBP and a 7.43 mmHg higher DBP than homozygotes for the rarer T allele. AA + AT genotype of rs3743966 was also found to maybe a risk factor of hypertension by logistic regression and transmission/disequilibrium test. AA + AT genotype of rs3743966 maybe a risk factor of EH. In conclusion, there was a significant association between the rs3743966 SNP in intron 12 and EH in Chinese hypertensive families.
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Affiliation(s)
- Yanling Wang
- Department of Cardiology, Xuanwu Hospital, Capital Medical University, Beijing, China
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46
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Yusef YR, Thomas W, Harvey BJ. Estrogen increases ENaC activity via PKCδ signaling in renal cortical collecting duct cells. Physiol Rep 2014; 2:2/5/e12020. [PMID: 24872356 PMCID: PMC4098747 DOI: 10.14814/phy2.12020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The most active estrogen, 17β‐estradiol (E2), has previously been shown to stimulate a female sex‐specific antisecretory response in the intestine. This effect is thought to contribute to the increase in whole body extracellular fluid (ECF) volume which occurs in high estrogen states, such as in the implantation window during estrous cycle. The increased ECF volume may be short‐circuited by a renal compensation unless estrogen exerts a proabsorptive effect in the nephron. Thus, the effect of E2 on ENaC in kidney cortical collecting duct (CCD) cells is of interest to understand estrogen regulation of ECF volume. Previous studies showed a rapid stimulatory effect of estrogen on ENaC in bronchial epithelium. In this study we examined if such a rapid effect on Na+ absorption could occur in the kidney. Experiments were carried out on murine M1‐CCD cell cultures. E2 (25 nmol/L) treatment caused a rapid‐onset (<15 min) and sustained increase in the amiloride‐sensitive Na+ current (INa) in CCD monolayers mounted in Ussing chambers (control, 1.9 ± 0.2 μA/cm2; E2, 4.7 ± 0.3 μA/cm2; n = 43, P < 0.001), without affecting the ouabain‐sensitive Na+/K+ pump current. The INa response to E2 was inhibited by PKCδ activity antagonism with rottlerin (5 μmol/L), inhibition of matrix metalloproteinases activity with GM6001 (1 μmol/L), inhibition of EGFR activity with AG1478 (10 μmol/L), inhibition of PLC activity with U‐73122 (10 μmol/L), and inhibition of estrogen receptors with the general ER antagonist ICI‐182780 (100 nmol/L). The estrogen activation of INa could be mimicked by the ERα agonist PPT (1 nmol/L). The nuclear excluded estrogen dendrimer conjugate (EDC) induced similar stimulatory effects on INa comparable to free E2. The end target for E2 stimulation of PKCδ was shown to be an increased abundance of the γ‐ENaC subunit in the apical plasma membrane of CCD cells. We have demonstrated a novel rapid “nongenomic” function of estrogen to stimulate ENaC via ERα‐EGFR transactivation in kidney CCD cells. We propose that the salt‐retaining effect of estrogen in the kidney together with its antisecretory action in the intestine are the molecular mechanisms causing the expanded ECF volume in high‐estrogen states. Estrogen stimulates sodium absorption in kidney cells. This rapid “nongenomic” response to estrogen is transduced via estrogen receptor transactivation of the epidermal growth factor receptor. The ER‐EGFR transactivation triggers a protein kinase signaling cascade which culminates in the insertion of sodium channel subunits into the cell membrane. Estrogen is a novel salt‐retaining hormone with proabsorptive effects in kidney and antisecretory actions in intestine.
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Affiliation(s)
- Yamil R Yusef
- Department of Molecular Medicine, Royal College of Surgeons in Ireland, RCSI Education and Research Centre, Beaumont Hospital, Dublin, Ireland
| | - Warren Thomas
- Department of Molecular Medicine, Royal College of Surgeons in Ireland, RCSI Education and Research Centre, Beaumont Hospital, Dublin, Ireland
| | - Brian J Harvey
- Department of Molecular Medicine, Royal College of Surgeons in Ireland, RCSI Education and Research Centre, Beaumont Hospital, Dublin, Ireland
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Davies M, Fraser SA, Galic S, Choy SW, Katerelos M, Gleich K, Kemp BE, Mount PF, Power DA. Novel mechanisms of Na+ retention in obesity: phosphorylation of NKCC2 and regulation of SPAK/OSR1 by AMPK. Am J Physiol Renal Physiol 2014; 307:F96-F106. [PMID: 24808538 DOI: 10.1152/ajprenal.00524.2013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Enhanced tubular reabsorption of salt is important in the pathogenesis of obesity-related hypertension, but the mechanisms remain poorly defined. To identify changes in the regulation of salt transporters in the kidney, C57BL/6 mice were fed a 40% fat diet [high-fat diet (HFD)] or a 12% fat diet (control diet) for 14 wk. Compared with control diet-fed mice, HFD-fed mice had significantly greater elevations in weight, blood pressure, and serum insulin and leptin levels. When we examined Na(+) transporter expression, Na(+)-K(+)-2Cl(-) cotransporter (NKCC2) was unchanged in whole kidney and reduced in the cortex, Na(+)-Cl(-) cotransporter (NCC) and α-epithelial Na(+) channel (ENaC) and γ-ENaC were unchanged, and β-ENaC was reduced. Phosphorylation of NCC was unaltered. Activating phosphorylation of NKCC2 at S126 was increased 2.5-fold. Activation of STE-20/SPS1-related proline-alanine-rich protein kinase (SPAK)/oxidative stress responsive 1 kinase (OSR1) was increased in kidneys from HFD-fed mice, and enhanced phosphorylation of NKCC2 at T96/T101 was evident in the cortex. Increased activity of NKCC2 in vivo was confirmed with diuretic experiments. HFD-fed mice had reduced activating phosphorylation of AMP-activated protein kinase (AMPK) in the renal cortex. In vitro, activation of AMPK led to a reduction in phospho-SPAK/phospho-OSR1 in AMPK(+/+) murine embryonic fibroblasts (MEFs), but no effect was seen in AMPK(-/-) MEFs, indicating an AMPK-mediated effect. Activation of the with no lysine kinase/SPAK/OSR1 pathway with low-NaCl solution invoked a greater elevation in phospho-SPAK/phospho-OSR1 in AMPK(-/-) MEFs than in AMPK(+/+) MEFs, consistent with a negative regulatory effect of AMPK on SPAK/OSR1 phosphorylation. In conclusion, this study identifies increased phosphorylation of NKCC2 on S126 as a hitherto-unrecognized mediator of enhanced Na(+) reabsorption in obesity and identifies a new role for AMPK in regulating the activity of SPAK/OSR1.
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Affiliation(s)
- Matthew Davies
- Kidney Laboratory, Institute for Breathing and Sleep, University of Melbourne, Heidelberg, Victoria, Australia; Department of Nephrology, University of Melbourne, Heidelberg, Victoria, Australia; Department of Medicine, University of Melbourne, Heidelberg, Victoria, Australia; and
| | - Scott A Fraser
- Kidney Laboratory, Institute for Breathing and Sleep, University of Melbourne, Heidelberg, Victoria, Australia
| | - Sandra Galic
- St. Vincent's Institute, Fitzroy, Victoria, Australia
| | - Suet-Wan Choy
- Kidney Laboratory, Institute for Breathing and Sleep, University of Melbourne, Heidelberg, Victoria, Australia; Department of Nephrology, University of Melbourne, Heidelberg, Victoria, Australia; Department of Medicine, University of Melbourne, Heidelberg, Victoria, Australia; and
| | - Marina Katerelos
- Kidney Laboratory, Institute for Breathing and Sleep, University of Melbourne, Heidelberg, Victoria, Australia
| | - Kurt Gleich
- Kidney Laboratory, Institute for Breathing and Sleep, University of Melbourne, Heidelberg, Victoria, Australia
| | - Bruce E Kemp
- St. Vincent's Institute, Fitzroy, Victoria, Australia
| | - Peter F Mount
- Kidney Laboratory, Institute for Breathing and Sleep, University of Melbourne, Heidelberg, Victoria, Australia; Department of Nephrology, University of Melbourne, Heidelberg, Victoria, Australia; Department of Medicine, University of Melbourne, Heidelberg, Victoria, Australia; and
| | - David A Power
- Kidney Laboratory, Institute for Breathing and Sleep, University of Melbourne, Heidelberg, Victoria, Australia; Department of Nephrology, University of Melbourne, Heidelberg, Victoria, Australia; Department of Medicine, University of Melbourne, Heidelberg, Victoria, Australia; and
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Adeva-Andany MM, Carneiro-Freire N, Donapetry-García C, Rañal-Muíño E, López-Pereiro Y. The importance of the ionic product for water to understand the physiology of the acid-base balance in humans. BIOMED RESEARCH INTERNATIONAL 2014; 2014:695281. [PMID: 24877130 PMCID: PMC4022011 DOI: 10.1155/2014/695281] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 03/31/2014] [Accepted: 04/04/2014] [Indexed: 12/13/2022]
Abstract
Human plasma is an aqueous solution that has to abide by chemical rules such as the principle of electrical neutrality and the constancy of the ionic product for water. These rules define the acid-base balance in the human body. According to the electroneutrality principle, plasma has to be electrically neutral and the sum of its cations equals the sum of its anions. In addition, the ionic product for water has to be constant. Therefore, the plasma concentration of hydrogen ions depends on the plasma ionic composition. Variations in the concentration of plasma ions that alter the relative proportion of anions and cations predictably lead to a change in the plasma concentration of hydrogen ions by driving adaptive adjustments in water ionization that allow plasma electroneutrality while maintaining constant the ionic product for water. The accumulation of plasma anions out of proportion of cations induces an electrical imbalance compensated by a fall of hydroxide ions that brings about a rise in hydrogen ions (acidosis). By contrast, the deficiency of chloride relative to sodium generates plasma alkalosis by increasing hydroxide ions. The adjustment of plasma bicarbonate concentration to these changes is an important compensatory mechanism that protects plasma pH from severe deviations.
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Affiliation(s)
| | | | | | - Eva Rañal-Muíño
- Hospital General Juan Cardona, C/ Pardo Bazán s/n, Ferrol, 15406 La Coruña, Spain
| | - Yosua López-Pereiro
- Hospital General Juan Cardona, C/ Pardo Bazán s/n, Ferrol, 15406 La Coruña, Spain
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Hallow KM, Lo A, Beh J, Rodrigo M, Ermakov S, Friedman S, de Leon H, Sarkar A, Xiong Y, Sarangapani R, Schmidt H, Webb R, Kondic AG. A model-based approach to investigating the pathophysiological mechanisms of hypertension and response to antihypertensive therapies: extending the Guyton model. Am J Physiol Regul Integr Comp Physiol 2014; 306:R647-62. [PMID: 24500431 DOI: 10.1152/ajpregu.00039.2013] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Reproducibly differential responses to different classes of antihypertensive agents are observed among hypertensive patients and may be due to interindividual differences in hypertension pathology. Computational models provide a tool for investigating the impact of underlying disease mechanisms on the response to antihypertensive therapies with different mechanisms of action. We present the development, calibration, validation, and application of an extension of the Guyton/Karaaslan model of blood pressure regulation. The model incorporates a detailed submodel of the renin-angiotensin-aldosterone system (RAAS), allowing therapies that target different parts of this pathway to be distinguished. Literature data on RAAS biomarker and blood pressure responses to different classes of therapies were used to refine the physiological actions of ANG II and aldosterone on renin secretion, renal vascular resistance, and sodium reabsorption. The calibrated model was able to accurately reproduce the RAAS biomarker and blood pressure responses to combinations of dual-RAAS agents, as well as RAAS therapies in combination with diuretics or calcium channel blockers. The final model was used to explore the impact of underlying mechanisms of hypertension on the blood pressure response to different classes of antihypertensive agents. Simulations indicate that the underlying etiology of hypertension can impact the magnitude of response to a given class of therapy, making a patient more sensitive to one class and less sensitive others. Given that hypertension is usually the result of multiple mechanisms, rather than a single factor, these findings yield insight into why combination therapy is often required to adequately control blood pressure.
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Affiliation(s)
- K Melissa Hallow
- Department of Modeling and Simulation, Primary Care Franchise, Novartis Pharmaceuticals Corporation, East Hanover, New Jersey
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50
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Chen J, Kleyman TR, Sheng S. Deletion of α-subunit exon 11 of the epithelial Na+ channel reveals a regulatory module. Am J Physiol Renal Physiol 2014; 306:F561-7. [PMID: 24402098 DOI: 10.1152/ajprenal.00587.2013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Epithelial Na(+) channel (ENaC) subunits (α, β, and γ) found in functional complexes are translated from mature mRNAs that are similarly processed by the inclusion of 13 canonical exons. We examined whether individual exons 3-12, encoding the large extracellular domain, are required for functional channel expression. Human ENaCs with an in-frame deletion of a single α-subunit exon were expressed in Xenopus oocytes, and their functional properties were examined by two-electrode voltage clamp. With the exception of exon 11, deletion of an individual exon eliminated channel activity. Channels lacking α-subunit exon 11 were hyperactive. Oocytes expressing this mutant exhibited fourfold greater amiloride-sensitive whole cell currents than cells expressing wild-type channels. A parallel fivefold increase in channel open probability was observed with channels lacking α-subunit exon 11. These mutant channels also exhibited a lost of Na(+) self-inhibition, whereas we found similar levels of surface expression of mutant and wild-type channels. In contrast, in-frame deletions of exon 11 from either the β- or γ-subunit led to a significant loss of channel activity, in association with a marked decrease in surface expression. Our results suggest that exon 11 within the three human ENaC genes encodes structurally homologous yet functionally diverse domains and that exon 11 in the α-subunit encodes a module that regulates channel gating.
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Affiliation(s)
- Jingxin Chen
- Renal-Electrolyte Div., Univ. of Pittsburgh, 3550 Terrace St., Pittsburgh, PA 15261.
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