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Mutchler SM, Whelan SCM, Marciszyn A, Chen J, Kleyman TR, Shi S. Role of paraoxonase 3 in regulating ENaC-mediated Na + transport in the distal nephron. J Physiol 2024; 602:737-757. [PMID: 38345534 PMCID: PMC10940207 DOI: 10.1113/jp285034] [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: 05/16/2023] [Accepted: 01/11/2024] [Indexed: 02/18/2024] Open
Abstract
Paraoxonase 3 (PON3) is expressed in the aldosterone-sensitive distal nephron, where filtered Na+ is reabsorbed mainly via the epithelial Na+ channel (ENaC) and Na+ -coupled co-transporters. We previously showed that PON3 negatively regulates ENaC through a chaperone mechanism. The present study aimed to determine the physiological role of PON3 in renal Na+ and K+ homeostasis. Pon3 knockout (KO) mice had higher amiloride-induced natriuresis and lower plasma [K+ ] at baseline. Single channel recordings in split-open tubules showed that the number of active channels per patch was significantly higher in KO mice, resulting in a higher channel activity in the absence of PON3. Although whole kidney abundance of ENaC subunits was not altered in Pon3 KOs, ENaC gamma subunit was more apically distributed within the connecting tubules and cortical collecting ducts of Pon3 KO kidneys. Additionally, small interfering RNA-mediated knockdown of PON3 in cultured mouse cortical collecting duct cells led to an increased surface abundance of ENaC gamma subunit. As a result of lower plasma [K+ ], sodium chloride co-transporter phosphorylation was enhanced in the KO kidneys, a phenotype that was corrected by a high K+ diet. Finally, PON3 expression was upregulated in mouse kidneys under dietary K+ restriction, potentially providing a mechanism to dampen ENaC activity and associated K+ secretion. Taken together, our results show that PON3 has a role in renal Na+ and K+ homeostasis through regulating ENaC functional expression in the distal nephron. KEY POINTS: Paraoxonase 3 (PON3) is expressed in the distal nephron of mouse kidneys and functions as a molecular chaperone to reduce epithelial Na+ channel (ENaC) expression and activity in heterologous expression systems. We examined the physiological role of PON3 in renal Na+ and K+ handling using a Pon3 knockout (KO) mouse model. At baseline, Pon3 KO mice had lower blood [K+ ], more functional ENaC in connecting tubules/cortical collecting ducts, higher amiloride-induced natriuresis, and enhanced sodium chloride co-transporter (NCC) phosphorylation. Upon challenge with a high K+ diet, Pon3 KO mice had normalized blood [K+ ] and -NCC phosphorylation but lower circulating aldosterone levels compared to their littermate controls. Kidney PON3 abundance was altered in mice under dietary K+ loading or K+ restriction, providing a potential mechanism for regulating ENaC functional expression and renal Na+ and K+ homeostasis in the distal nephron.
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Affiliation(s)
| | | | - Allison Marciszyn
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jingxin Chen
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Thomas R. Kleyman
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Shujie Shi
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
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Hypokalemia and hypertensive urgency in a 10-year-old boy: Answers. Pediatr Nephrol 2021; 36:3629-3631. [PMID: 33825041 DOI: 10.1007/s00467-021-05072-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 03/10/2021] [Accepted: 03/17/2021] [Indexed: 10/21/2022]
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He X, Modi Z, Else T. Hereditary causes of primary aldosteronism and other disorders of apparent excess mineralocorticoid activity. Gland Surg 2020; 9:150-158. [PMID: 32206607 DOI: 10.21037/gs.2019.11.20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Secondary hypertension is a common condition with a broad differential diagnosis. Identification of the true cause of hypertension can be critical for guiding appropriate management. Here, we review hereditary conditions underlying the most common cause of secondary hypertension, primary aldosteronism, as well as other disorders impacting various levels of mineralocorticoid action. Recently, several pathogenic variants of ion channels have been described as etiologies of familial aldosteronism. Defects in steroid hormone synthesis cause hypertension in 11β-hydroxylase deficiency and 17α-hydroxylase deficiency, two types of congenital adrenal hyperplasia. Inappropriate activation of mineralocorticoid receptors underlies the syndrome of apparent mineralocorticoid excess and constitutive activation of the mineralocorticoid receptor. Finally, Liddle syndrome and pseudohypoaldosteronism type 2 are disorders impacting the function of renal sodium channels, the endpoint of mineralocorticoid action. We discuss the pathophysiology, clinical presentation, diagnosis and management of these low renin hypertension states that ultimately result in apparent excess mineralocorticoid activity.
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Affiliation(s)
- Xin He
- Division of Metabolism, Endocrinology, and Diabetes, University of Michigan, Ann Arbor, MI, USA
| | - Zubin Modi
- Division of Pediatric Nephrology, Department of Pediatrics, University of Michigan, Ann Arbor, MI, USA.,Susan B. Meister Child Health Evaluation and Research (CHEAR) Center, University of Michigan, Ann Arbor, MI, USA
| | - Tobias Else
- Division of Metabolism, Endocrinology, and Diabetes, University of Michigan, Ann Arbor, MI, USA
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4
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Ding X, Jia N, Zhao C, Zhong Y, Dai D, Zhao Y, Xu C, Cai J, Wang Q, He Q. A family with Liddle's syndrome caused by a new c.1721 deletion mutation in the epithelial sodium channel β-subunit. Exp Ther Med 2019; 17:2777-2784. [PMID: 30930974 DOI: 10.3892/etm.2019.7270] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 11/01/2018] [Indexed: 11/06/2022] Open
Abstract
A 19-year-old male with early refractory hypertension, hypokalemia, serum potassium level of 3.4 mmol/l and hypoaldosteronemia was indicated in the present study. According to the results of laboratory tests and examinations, the patient was suspected of having Liddle's syndrome (LS). Genetic analysis of SCNN1B revealed a deletion mutation (c.1721delC). This mutation caused a length extension of SCNN1B coding sequence, which resulted in p.Pro574HisfsX675. A total of 34 family members were enrolled in the study and 29 of these family members underwent genetic testing. A total of 10 family members were clinically diagnosed with hypertension. Notably, 5 family members shared the same gene mutation as the proband and all cases with the mutation had hypertension. Blood pressure of the gene mutation carriers was well controlled by tailored treatment. In conclusion, a patient with early onset and refractory hypertension, hypokalemia and hypoaldosteronemia was diagnosed clinically and genetically with LS. Notably, a novel mutation (c.1721delC) was identified by DNA analysis. The present findings indicate that genetic analysis is useful, not only in the diagnosis of LS, but also in designing a tailored treatment.
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Affiliation(s)
- Xia Ding
- Department of Cardiology, Beijing Hospital, National Center of Gerontology, Beijing 100730, P.R. China.,Department of Nephrology, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, P.R. China
| | - Na Jia
- Department of Cardiology, Beijing Hospital, National Center of Gerontology, Beijing 100730, P.R. China
| | - Cong Zhao
- Department of Cardiology, Beijing Hospital, National Center of Gerontology, Beijing 100730, P.R. China
| | - You Zhong
- Department of Cardiology, Beijing Hospital, National Center of Gerontology, Beijing 100730, P.R. China
| | - Dapeng Dai
- The Key Laboratory of Geriatrics, Beijing Hospital and Beijing Institute of Geriatrics, Ministry of Health, Beijing 100730, P.R. China
| | - Yuanyuan Zhao
- Human Genome Research Center and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China
| | - Chengqi Xu
- Human Genome Research Center and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China
| | - Jianping Cai
- The Key Laboratory of Geriatrics, Beijing Hospital and Beijing Institute of Geriatrics, Ministry of Health, Beijing 100730, P.R. China
| | - Qing Wang
- Human Genome Research Center and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China
| | - Qing He
- Department of Cardiology, Beijing Hospital, National Center of Gerontology, Beijing 100730, P.R. China
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Yamaguchi E, Yoshikawa K, Nakaya I, Kato K, Miyasato Y, Nakagawa T, Kakizoe Y, Mukoyama M, Soma J. Liddle's-like syndrome associated with nephrotic syndrome secondary to membranous nephropathy: the first case report. BMC Nephrol 2018; 19:122. [PMID: 29792170 PMCID: PMC5966895 DOI: 10.1186/s12882-018-0916-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 05/11/2018] [Indexed: 12/20/2022] Open
Abstract
Background Liddle’s syndrome is a rare monogenic form of hypertension caused by truncating or missense mutations in the C termini of the epithelial sodium channel (ENaC) β or γ subunits. Patients with this syndrome present with early onset of hypertension, hypokalemia, metabolic alkalosis, hyporeninemia and hypoaldosteronism, and a potassium-sparing diuretics (triamterene or amiloride) can drastically improves the disease condition. Although elderly patients having these characteristics were considered to have Liddle’s syndrome or Liddle’s-like syndrome, no previous report has indicated that Liddle’s-like syndrome could be caused by nephrotic syndrome of primary glomerular disease, which is characterized by urinary excretion of > 3 g of protein/day plus edema and hypoalbuminemia, or has explained how the activity function of ENaC could be affected in the setting of high proteinuria. Case presentation A 65-year-old Japanese man presented with nephrotic syndrome. He had no remarkable family history, but had a medical history of hypertension and hyperlipidemia. On admission, hypertension, spironolactone-resistant hypokalemia (2.43 mEq/l), hyporeninemic hypoaldosteronism, and metabolic alkalosis, which suggested Liddle’s syndrome, were observed. Treatment with triamterene together with a steroid for nephrotic syndrome resulted in rapid and remarkable effective on improvements of hypertension, hypokalemia, and edema of the lower extremities. Renal biopsy revealed membranous nephropathy (MN) as the cause of nephrotic syndrome, and advanced gastric cancer was identified on screening examination for cancers that could be associated with the development of MN. After total gastrectomy, triamterene was not required and proteinuria decreased. A mutation in the β or γ subunits of the ENaC gene was not identified. Conclusion We reported for the first time a case of Liddle’s-like syndrome associated with nephrotic syndrome secondary to MN. Aberrant activation of ENaC was suggested transient during the period of high proteinuria, and the activation was reversible with a decrease in proteinuria.
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Affiliation(s)
- Eriko Yamaguchi
- Department of Nephrology and Rheumatology, Iwate Prefectural Central Hospital, 1-4-1, Morioka, 020-0066, Japan
| | - Kazuhiro Yoshikawa
- Department of Nephrology and Rheumatology, Iwate Prefectural Central Hospital, 1-4-1, Morioka, 020-0066, Japan
| | - Izaya Nakaya
- Department of Nephrology and Rheumatology, Iwate Prefectural Central Hospital, 1-4-1, Morioka, 020-0066, Japan
| | - Karen Kato
- Department of Nephrology and Rheumatology, Iwate Prefectural Central Hospital, 1-4-1, Morioka, 020-0066, Japan
| | - Yoshikazu Miyasato
- Department of Nephrology, Kumamoto University School of Medicine, Honjyo 1-1-1, Chuo-Ku, Kumamoto, 860-8556, Japan
| | - Terumasa Nakagawa
- Department of Nephrology, Kumamoto University School of Medicine, Honjyo 1-1-1, Chuo-Ku, Kumamoto, 860-8556, Japan
| | - Yutaka Kakizoe
- Department of Nephrology, Kumamoto University School of Medicine, Honjyo 1-1-1, Chuo-Ku, Kumamoto, 860-8556, Japan
| | - Masashi Mukoyama
- Department of Nephrology, Kumamoto University School of Medicine, Honjyo 1-1-1, Chuo-Ku, Kumamoto, 860-8556, Japan
| | - Jun Soma
- Department of Nephrology and Rheumatology, Iwate Prefectural Central Hospital, 1-4-1, Morioka, 020-0066, Japan.
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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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Analysis of the genes involved in Mendelian forms of low-renin hypertension in Chinese early-onset hypertensive patients. J Hypertens 2018; 36:502-509. [DOI: 10.1097/hjh.0000000000001556] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Pagani L, Diekmann Y, Sazzini M, De Fanti S, Rondinelli M, Farnetti E, Casali B, Caretto A, Novara F, Zuffardi O, Garagnani P, Mantero F, Thomas MG, Luiselli D, Rossi E. Three Reportedly Unrelated Families With Liddle Syndrome Inherited From a Common Ancestor. Hypertension 2017; 71:273-279. [PMID: 29229744 DOI: 10.1161/hypertensionaha.117.10491] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 10/31/2017] [Accepted: 11/14/2017] [Indexed: 12/31/2022]
Abstract
Liddle syndrome is considered a rare Mendelian hypertension. We have previously described 3 reportedly unrelated families, native of an Italian area around the Strait of Messina, carrying the same mutation (βP617L) of the epithelial sodium channel. The aims of our study were (1) to evaluate whether a close genomic relationship exists between the 3 families through the analysis of mitochondrial DNA and Y chromosome; and (2) to quantify the genomic relatedness between the patients with Liddle syndrome belonging to the 3 families and assess the hypothesis of a mutation shared through identity by descent. HVRI (the hypervariable region I) of the mitochondrial DNA genome and the Y chromosome short tandem repeats profiles were analyzed in individuals of the 3 families. Genotyping 542 585 genome-wide single nucleotide polymorphisms was performed in all the patients with Liddle syndrome of the 3 families and some of their relatives. A panel of 780 healthy Italian adult samples typed for the same set of markers was used as controls. espite different lineages between the 3 families based on the analysis of mitochondrial DNA and Y chromosome, the 3 probands and their 6 affected relatives share the same ≈5 Mbp long haplotype which encompasses the mutant allele. Using an approach based on coalescent theory, we estimate that the 3 families inherited the mutant allele from a common ancestor ≈13 generations ago and that such an ancestor may have left ≈20 carriers alive today. The prevalence of Liddle syndrome in the region of origin of the 3 families may be much higher than that estimated worldwide.
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Affiliation(s)
- Luca Pagani
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.)
| | - Yoan Diekmann
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.)
| | - Marco Sazzini
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.)
| | - Sara De Fanti
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.)
| | - Maurizio Rondinelli
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.)
| | - Enrico Farnetti
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.)
| | - Bruno Casali
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.)
| | - Amelia Caretto
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.)
| | - Francesca Novara
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.)
| | - Orsetta Zuffardi
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.)
| | - Paolo Garagnani
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.)
| | - Franco Mantero
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.)
| | - Mark G Thomas
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.)
| | - Donata Luiselli
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.)
| | - Ermanno Rossi
- From the Department of Biology (L.P.) and Endocrinology Unit, Department of Medicine (F.M.), University of Padova, Italy; Estonian Biocentre, Tartu (L.P.); Research Department of Genetics, Evolution and Environment, University College London, United Kingdom (Y.D., M.G.T.); Department of Biological Geological and Environmental Sciences (M.S., S.D.F., D.L.) and Department of Experimental, Diagnostic and Specialty Medicine (P.G.), University of Bologna, Italy; IRCCS Centro Cardiologico Monzino, Milano, Italy (M.R.); Department of Oncology and Advanced Technologies, Laboratory of Molecular Biology (E.F., B.C.) and Department of Internal Medicine (E.R.), IRCCS Santa Maria Nuova Hospital, Reggio Emilia, Italy; Department of Endocrinology and Metabolic Diseases, San Raffaele Scientific Institute, Milano, Italy (A.C.); and Department of Molecular Medicine, University of Pavia, Italy (F.N., O.Z.).
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9
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Chen L, Higgins PJ, Zhang W. Development and Diseases of the Collecting Duct System. Results Probl Cell Differ 2017; 60:165-203. [PMID: 28409346 DOI: 10.1007/978-3-319-51436-9_7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The collecting duct of the mammalian kidney is important for the regulation of extracellular volume, osmolarity, and pH. There are two major structurally and functionally distinct cell types: principal cells and intercalated cells. The former regulates Na+ and water homeostasis, while the latter participates in acid-base homeostasis. In vivo lineage tracing using Cre recombinase or its derivatives such as CreGFP and CreERT2 is a powerful new technique to identify stem/progenitor cells in their native environment and to decipher the origins of the tissue that they give rise to. Recent studies using this technique in mice have revealed multiple renal progenitor cell populations that differentiate into various nephron segments and collecting duct. In particular, emerging evidence suggests that like principal cells, most of intercalated cells originate from the progenitor cells expressing water channel Aquaporin 2. Mutations or malfunctions of the channels, pumps, and transporters expressed in the collecting duct system cause various human diseases. For example, gain-of-function mutations in ENaC cause Liddle's syndrome, while loss-of-function mutations in ENaC lead to Pseudohypoaldosteronism type 1. Mutations in either AE1 or V-ATPase B1 result in distal renal tubular acidosis. Patients with disrupted AQP2 or AVPR2 develop nephrogenic diabetes insipidus. A better understanding of the function and development of the collecting duct system may facilitate the discovery of new therapeutic strategies for treating kidney disease.
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Affiliation(s)
- Lihe Chen
- Epithelial Systems Biology Laboratory, Systems Biology Center, NHLBI, Bethesda, MD, 20892-1603, USA
| | - Paul J Higgins
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, MC-165, 47 New Scotland Avenue, Albany, NY, 12208, USA
| | - Wenzheng Zhang
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, MC-165, 47 New Scotland Avenue, Albany, NY, 12208, USA.
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10
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Yang KQ, Lu CX, Fan P, Zhang Y, Meng X, Dong XQ, Luo F, Liu YX, Zhang HM, Wu HY, Cai J, Zhang X, Zhou XL. Genetic screening of SCNN1B and SCNN1G genes in early-onset hypertensive patients helps to identify Liddle syndrome. Clin Exp Hypertens 2017; 40:107-111. [PMID: 28718682 DOI: 10.1080/10641963.2017.1334799] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Kun-Qi Yang
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Chao-Xia Lu
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Peng Fan
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Ying Zhang
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xu Meng
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xue-Qi Dong
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Fang Luo
- Department of Cardiology, 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 Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Hui-Min Zhang
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Hai-Ying Wu
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jun Cai
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xue Zhang
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xian-Liang Zhou
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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11
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Kuang ZM, Wang Y, Wang JJ, Liu JH, Zeng R, Zhou Q, Yu ZQ, Jiang L. The importance of genetic counseling and genetic screening: a case report of a 16-year-old boy with resistant hypertension and severe hypokalemia. ACTA ACUST UNITED AC 2017; 11:136-139. [DOI: 10.1016/j.jash.2017.01.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 10/28/2016] [Accepted: 01/24/2017] [Indexed: 10/20/2022]
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12
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Büyükkaragöz B, Yilmaz AC, Karcaaltincaba D, Ozdemir O, Ludwig M. Liddle syndrome in a Turkish family with heterogeneous phenotypes. Pediatr Int 2016; 58:801-4. [PMID: 27325428 DOI: 10.1111/ped.12985] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 02/13/2016] [Accepted: 03/09/2016] [Indexed: 11/30/2022]
Abstract
Liddle syndrome (LS) is a familial disease characterized by early onset hypertension (HT). Although regarded as rare, its incidence may be greater than expected because the classical findings of hypokalemic metabolic alkalosis with suppressed renin and aldosterone levels are not consistently present. Herein, we present the case of an adolescent boy and maternal relatives who were followed up with misdiagnosis of essential HT for a long duration. Clinical diagnosis of LS was confirmed on genetic analysis. Despite carrying the same mutation, the index patient and the family members manifested heterogeneous phenotypes of the disease including age at presentation, degree of HT, presence of hypokalemia and renal/cardiac complications. LS should be considered in the differential diagnosis of HT in children with a strong family history of HT resistant to conventional treatment; and genetic screening should be performed in these circumstances.
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Affiliation(s)
- Bahar Büyükkaragöz
- Department of Pediatric Nephrology, Keciören Research and Training Hospital, Ankara, Turkey
| | - Aysun Caltik Yilmaz
- Department of Pediatric Nephrology, Keciören Research and Training Hospital, Ankara, Turkey
| | | | - Osman Ozdemir
- Department of Pediatric Cardiology, Keciören Research and Training Hospital, Ankara, Turkey
| | - Michael Ludwig
- Department of Clinical Biochemistry and Clinical Pharmacology, University of Bonn, Bonn, Germany
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13
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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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14
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Magill SB. Pathophysiology, diagnosis, and treatment of mineralocorticoid disorders. Compr Physiol 2015; 4:1083-119. [PMID: 24944031 DOI: 10.1002/cphy.c130042] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The renin-angiotensin-aldosterone system (RAAS) is a major regulator of blood pressure control, fluid, and electrolyte balance in humans. Chronic activation of mineralocorticoid production leads to dysregulation of the cardiovascular system and to hypertension. The key mineralocorticoid is aldosterone. Hyperaldosteronism causes sodium and fluid retention in the kidney. Combined with the actions of angiotensin II, chronic elevation in aldosterone leads to detrimental effects in the vasculature, heart, and brain. The adverse effects of excess aldosterone are heavily dependent on increased dietary salt intake as has been demonstrated in animal models and in humans. Hypertension develops due to complex genetic influences combined with environmental factors. In the last two decades, primary aldosteronism has been found to occur in 5% to 13% of subjects with hypertension. In addition, patients with hyperaldosteronism have more end organ manifestations such as left ventricular hypertrophy and have significant cardiovascular complications including higher rates of heart failure and atrial fibrillation compared to similarly matched patients with essential hypertension. The pathophysiology, diagnosis, and treatment of primary aldosteronism will be extensively reviewed. There are many pitfalls in the diagnosis and confirmation of the disorder that will be discussed. Other rare forms of hyper- and hypo-aldosteronism and unusual disorders of hypertension will also be reviewed in this article.
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Affiliation(s)
- Steven B Magill
- Division of Endocrinology, Metabolism, and Clinical Nutrition, Department of Medicine, Medical College of Wisconsin, Menomonee Falls, Wisconsin
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15
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Molecular genetics of Liddle's syndrome. Clin Chim Acta 2014; 436:202-6. [PMID: 24882431 DOI: 10.1016/j.cca.2014.05.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 05/11/2014] [Accepted: 05/15/2014] [Indexed: 01/04/2023]
Abstract
Liddle's syndrome, an autosomal dominant form of monogenic hypertension, is characterized by salt-sensitive hypertension with early penetrance, hypokalemia, metabolic alkalosis, suppression of plasma rennin activity and aldosterone secretion, and a clear-cut response to epithelial sodium channel (ENaC) blockers but not spironolactone therapy. Our understanding of ENaCs and Na(+) transport defects has expanded greatly over the past two decades and provides detailed insight into the molecular basis of Liddle's syndrome. In this review, we offer an overview of recent advances in understanding the molecular genetics of Liddle's syndrome, involving mutation analysis, molecular mechanisms and genetic testing. The ENaC in the distal nephron is composed of α, β and γ subunits that share similar structures. Mutations associated with Liddle's syndrome are positioned in either β or γ subunits and disturb or truncate a conserved proline-rich sequence (i.e., PY motif), leading to constitutive activation of the ENaC. Genetic testing has made it possible to make accurate diagnoses and develop tailored therapies for mutation carriers.
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16
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Gong L, Chen J, Shao L, Song W, Hui R, Wang Y. Phenotype-genotype analysis in two Chinese families with Liddle syndrome. Mol Biol Rep 2014; 41:1569-75. [PMID: 24474657 DOI: 10.1007/s11033-013-3003-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 12/30/2013] [Indexed: 10/25/2022]
Abstract
The families with Liddle syndrome show marked phenotypic variation in blood pressure, serum potassium and other clinical manifestations. Here we analyzed the correlation of genotype-phenotype in two Chinese families with Liddle syndrome. The sequence of C-terminus of SCNN1B and SCNN1G were screened in the two families with likely Liddle syndrome. In addition to hypertension and hypokalemia, one of the two pedigrees had sudden death in their family members, so the exons of 428 reported genes-related to cardiovascular diseases were screened as well in the family. A heterozygous βR566X nonsense mutation was found in the proband-1 in the first pedigree, and the proband's sister and father. They showed mild phenotype with hypertension under control. In contrast, two of the four previous studies report that the mutation causes severe phenotype. A heterozygous βR597PfrX607 frameshift mutation was identified in the proband-2 in the second pedigree, showing malignant phenotype including resistant hypertension, hypokalemia, higher PRA and plasma angiotensin II levels. Both the proband-2 and the proband-2's father had sudden death in their twenties, but no meaningful mutations were found by screening of the exons in 428 cardiovascular disease-related genes. However, the same mutation has been related to moderate phenotype in previous studies. Our results confirmed that the phenotypes of Liddle syndrome are varied significantly even with the same mutation. The mechanisms why the same mutation causes very different phenotype need to be explored because intervention of these modifiers may change the disease course and prognosis accordingly.
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Affiliation(s)
- Ling Gong
- 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, 167 Beilishi Road, Beijing, 100037, China
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17
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Gao L, Wang L, Liu Y, Zhou X, Hui R, Hu A. A family with Liddle syndrome caused by a novel missense mutation in the PY motif of the beta-subunit of the epithelial sodium channel. J Pediatr 2013; 162:166-70. [PMID: 22809657 DOI: 10.1016/j.jpeds.2012.06.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 05/23/2012] [Accepted: 06/07/2012] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To identify the gene mutation in β and γ subunits of the epithelial sodium channel (ENaC) in an adolescent and family members with Liddle syndrome, an autosomal dominant form of secondary hypertension. STUDY DESIGN We screened an adolescent with severe hypertension who was clinically diagnosed with Liddle syndrome for mutations in the C-terminus of the SCNN1B and SCNN1G genes. We also screened for these mutations in his family members, in 100 hypertensive patients, and in 100 controls. RESULTS The index case, a 14-year-old boy, was diagnosed with Liddle syndrome by the identification of a novel missense mutation, P614L, in the PY motif of the β subunit of the ENaC. Testing of relatives considered at risk revealed 6 subjects heterozygous for the mutation. All genetically affected subjects had a history of severe hypertension as well as hypokalemia. No other variants in the β or γ subunits of the ENaC were detected. CONCLUSION Based on direct DNA sequencing, we have detected a novel mutation that causes Liddle syndrome. This confirms the diagnosis and helps guide effective therapy for this adolescent and his affected relatives. These findings provide further evidence that the conserved PY motif is critical to regulation of ENaC activity.
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Affiliation(s)
- Linggen Gao
- Department of Cardiology, FuWai Hospital and Cardiovascular Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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18
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Bogdanović R, Kuburović V, Stajić N, Mughal SS, Hilger A, Ninić S, Prijić S, Ludwig M. Liddle syndrome in a Serbian family and literature review of underlying mutations. Eur J Pediatr 2012; 171:471-8. [PMID: 21956615 DOI: 10.1007/s00431-011-1581-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 09/08/2011] [Indexed: 12/13/2022]
Abstract
UNLABELLED Severe and reproducible low-renin hypertension responsive to salt restriction and amiloride-thiazide therapy in a 13-year-old otherwise asymptomatic boy suggested Liddle syndrome. This assumption was strengthened by a positive family history of hypertension poorly responsive to conventional treatment or sudden deaths under 40 years of age in four generations. DNA analysis of the beta and gamma subunits of the epithelial sodium channel revealed a heterozygous mutation c.C1852T (p.Pro618Ser) in the SCNN1B gene in the patient and in both his hypertensive mother and uncle. A PubMed search revealed 21 different disease-causing mutations reported to date, all but two clustering in the cytoplasmic C-terminal regions of either beta (16 mutations) or gamma (5) subunit, leading to a three- to eightfold increase in the amiloride-sensitive sodium current. Inter- and intrafamilial variability in both hypertension and hypokalemia were disclosed, which may not be obligatory among the subjects carrying a Liddle mutation. CONCLUSION Liddle syndrome should be considered as a cause of hypertension in children or adolescents particularly with suppressed renin activity. Early diagnosis and appropriately tailored treatment avoid complications of long-term unrecognized or inappropriately managed hypertension.
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Abstract
The epithelial Na(+) channel (ENaC) and acid-sensitive ion channel (ASIC) branches of the ENaC/degenerin superfamily of cation channels have drawn increasing attention as potential therapeutic targets in a variety of diseases and conditions. Originally thought to be solely expressed in fluid absorptive epithelia and in neurons, it has become apparent that members of this family exhibit nearly ubiquitous expression. Therapeutic opportunities range from hypertension, due to the role of ENaC in maintaining whole body salt and water homeostasis, to anxiety disorders and pain associated with ASIC activity. As a physiologist intrigued by the fundamental mechanics of salt and water transport, it was natural that Dale Benos, to whom this series of reviews is dedicated, should have been at the forefront of research into the amiloride-sensitive sodium channel. The cloning of ENaC and subsequently the ASIC channels has revealed a far wider role for this channel family than was previously imagined. In this review, we will discuss the known and potential roles of ENaC and ASIC subunits in the wide variety of pathologies in which these channels have been implicated. Some of these, such as the role of ENaC in Liddle's syndrome are well established, others less so; however, all are related in that the fundamental defect is due to inappropriate channel activity.
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Affiliation(s)
- Yawar J Qadri
- Department of Physiology and Biophysics, University of Alabama at Birmingham, AL 35294, USA
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Rossi E, Farnetti E, Nicoli D, Sazzini M, Perazzoli F, Regolisti G, Grasselli C, Santi R, Negro A, Mazzeo V, Mantero F, Luiselli D, Casali B. A clinical phenotype mimicking essential hypertension in a newly discovered family with Liddle's syndrome. Am J Hypertens 2011; 24:930-5. [PMID: 21525970 DOI: 10.1038/ajh.2011.76] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Liddle's syndrome (LS) is a monogenic form of hypertension simulating a mineralocorticoid excess, and is currently suspected in young hypokalemic hypertensives. The aims of the study were: (i) to evaluate the clinical phenotype of LS in a newly identified Italian family of Sicilian origin carrying a gain-of-function mutation of the β subunit of the epithelial sodium channel (ENaC) (P617L) previously reported by our group in an apparently unrelated Sicilian patient presenting the typical phenotype of LS including hypokalemia; (ii) to determine whether an unknown biological relationship exists between the newly identified family and the family of the proband previously reported. METHODS Genetic analysis was performed in the present family, in the individual in which the βP617L mutation was first observed, and in his relatives. RESULTS βP617L mutation was identified in the proband and in three maternal relatives. None of them showed hypokalemia. Mild to severe early onset hypertension and left ventricular hypertrophy were present in all of them. Analysis of mitochondrial DNA (mtDNA) and Y chromosome profiles in the present family and in the proband's family previously reported showed the absence of a relationship between them. The availability of only one carrier of the mutation in one of the two families meant that a genetic analysis able to assess a founder effect was not feasible. CONCLUSIONS LS should be considered in all cases of early onset hypertension, independently of the plasma potassium concentration. The incidence of LS may be greater than is currently thought, because hypokalemia is not invariably present.
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Jones ES, Owen EP, Davidson JS, Van Der Merwe L, Rayner BL. The R563Q mutation of the epithelial sodium channel beta-subunit is associated with hypertension. Cardiovasc J Afr 2010; 22:241-4. [PMID: 21107496 PMCID: PMC3721827 DOI: 10.5830/cvja-2010-084] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Accepted: 09/07/2010] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND A high prevalence of the R563Q mutation of the epithelial sodium channel β-subunit has been reported in South African hypertensives compared with unrelated normotensive controls. To delineate the effects of this mutation against a more uniform genetic background, this study investigated the association of the mutation with hypertension within affected kindreds. METHODS Forty-five index patients and members of their kindreds were studied. Blood pressure, serum potassium and the presence of the R563Q mutation were determined. RESULTS Of the 136 individuals studied, 89 were heterozygous for the R563Q mutation and 47 homozygous RR. The mean arterial pressure was significantly higher in the R563Q heterozygous group (p = 0.005) after adjusting for gender, race, age and kindred membership. Of the R563Q heterozygous subjects, 71 (80%) had hypertension, while 17 (36%) of the R563Q homozygous RR subjects were hypertensive. Six R563Q heterozygous subjects had hypokalaemia and one R563Q homozygous RR subject had hypokalaemia, but the difference was not statistically significant. Two heterozygous patients had Liddle's syndrome, both occurring during pregnancy. CONCLUSION The R563Q mutation of β-ENaC is associated with hypertension within affected kindreds, but does not usually cause the full Liddle's syndrome phenotype.
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Affiliation(s)
- E S Jones
- Division of Hypertension, Groote Schuur Hospital and University of Cape Town, South Africa
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Sawathiparnich P, Sumboonnanonda A, Weerakulwattana P, Limwongse C. A novel mutation in the beta-subunit of the epithelial sodium channel gene (SCNN1B) in a Thai family with Liddle's syndrome. J Pediatr Endocrinol Metab 2009; 22:85-9. [PMID: 19344079 DOI: 10.1515/jpem.2009.22.1.85] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Liddle's syndrome is a rare form of autosomal dominant hypertension with early penetrance and cardiovascular sequelae. It is caused by missense or frameshift mutations in the epithelial sodium channel (ENaC) gene resulting in excessive salt and water resorption from the distal nephron, volume expansion, and suppression of plasma renin activity and serum aldosterone secretion. Treatment with an antagonist of the amiloride-sensitive ENaC, amiloride or triamterine, can correct hypertension and biochemical abnormalities in Liddle's syndrome by closing the sodium channels. Missense and truncation mutations at the C-terminus of the ENaC gene have been found in two of the three genes encoding beta- and gamma-subunits of ENaC. We report here a Thai family with Liddle's syndrome caused by a novel P615H missense mutation in the proline-rich domain of the SCNN1B gene coding for the beta-subunit of ENaC. This mutation occurs within the conserved proline-rich (PY) motif at the C-terminal end and emphasizes the critical role of this motif in ENaC internalization. The presence of severe hypertension and/or a suggestive family history of hypertension with or without hypokalemia in young children should always raise a suspicion of Liddle's syndrome.
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Affiliation(s)
- Pairunyar Sawathiparnich
- Division of Pediatric Endocrinology , Department of Pediatrics, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
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Liddle's syndrome caused by a novel missense mutation (P617L) of the epithelial sodium channel β subunit. J Hypertens 2008; 26:921-7. [DOI: 10.1097/hjh.0b013e3282f85dfe] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Wang Y, Zheng Y, Chen J, Wu H, Zheng D, Hui R. A novel epithelial sodium channel gamma-subunit de novo frameshift mutation leads to Liddle syndrome. Clin Endocrinol (Oxf) 2007; 67:801-4. [PMID: 17634077 DOI: 10.1111/j.1365-2265.2007.02967.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Liddle syndrome is a rare autosomal-dominant monogenic form of hypertension caused by mutations in the C-termini of the epithelial sodium channel beta- or gamma-subunit encoded by SCNN1B and SCNN1G, respectively, and often presenting with a familial history of hypertension. The purpose of this study was to determine whether mutations of SCNN1B or SCNN1G were present in a patient clinically suspected to have Liddle syndrome with no familial history of hypertension. DESIGN AND PATIENTS We screened the C-terminus of SCNN1B and SCNN1G in the patient, and also screened for the mutation in his parents, 50 hypertensive patients and 50 controls. RESULTS In this patient, no mutations were found in the C-terminus of SCNN1B. However, we found a frameshift mutation caused by an 'AGCTC' deletion at the 583 codon in SCNN1G. The frameshift resulted in a new termination site at the 585 codon of the gamma-subunit and the deletion of its PY motif. Neither his parents nor 50 randomly selected patients with hypertension nor 50 controls have the mutation, indicating that this is a de novo mutation and not a common genetic polymorphism. CONCLUSION The de novo mutation is the first reported frameshift of the gamma-subunit causing Liddle syndrome. These data imply that a familial history of hypertension is not an essential criterion for the diagnosis of Liddle syndrome.
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Affiliation(s)
- Yibo Wang
- Key Laboratory for Clinical Cardiovascular Genetics, Ministry of Education, Beijing, People's Republic of China
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Staub O, Verrey F. Impact of Nedd4 proteins and serum and glucocorticoid-induced kinases on epithelial Na+ transport in the distal nephron. J Am Soc Nephrol 2005; 16:3167-74. [PMID: 16192418 DOI: 10.1681/asn.2005050454] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The precise control of BP occurs via Na(+) homeostasis and involves the precise regulation of the epithelial Na(+) channel (ENaC) in the aldosterone-sensitive distal nephron. This has been corroborated by the linkage of mutations in the genes encoding ENaC subunits and Liddle's syndrome, a heritable form of human hypertension. Mapping of these mutations on ENaC indicated that inactivation of PY motifs is responsible and leads to the proposition that the channel interacts via its PY motifs with the WW domains of the Nedd4/Nedd4-like ubiquitin-protein ligase family. It is now well established that the cell surface expression of ENaC is controlled via ubiquitylation by this protein family and that this ubiquitylation is regulated by the aldosterone-induced protein serum and glucocorticoid induced kinase 1.
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Affiliation(s)
- Olivier Staub
- Department of Pharmacology & Toxicology, University of Lausanne, Rue du Bugnon 27, 1005 Lausanne, Switzerland.
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Ciechanowicz A, Dolezel Z, Placha G, Starha J, Góra J, Gaciong Z, Brodkiewicz A, Adler G. Liddle syndrome caused by P616R mutation of the epithelial sodium channel beta subunit. Pediatr Nephrol 2005; 20:837-8. [PMID: 15856328 DOI: 10.1007/s00467-004-1793-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Andrzej Ciechanowicz
- Pomeranian Medical University, Department of Pathobiochemistry and Molecular Biology, ul. Powstancow Wlkp. Szczecin, Poland.
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Abstract
Monogenic forms of low renin hypertension can now be identified in a large and heterogeneous family of hypertensive patients with highly specific etiologies and similar clinical manifestations. These include the following well-characterized disorders: apparent mineralocorticoid excess, Liddle's Syndrome, steroid 11beta-hydroxylase (11beta-OHD) and steroid 17-hydroxylase (17-OHD) deficiencies, glucocorticoid-remediable hyperaldosteronism (familial hyperaldosteronism type I), familial hyperaldosteronism type II, hypertension exacerbated by pregnancy and primary hyperaldosteronism (Conn's syndrome). The successful elucidation of specific DNA mutations in most of these conditions has emphasized the role of molecular genetics in hypertension, a field in which diagnosis can now be made on proven genetic evidence. The current knowledge of these genetic markers enables practitioners to make precise diagnoses, and to initiate specific therapy, in patients with these relatively uncommon but interesting and often treatable forms of hypertension.
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Affiliation(s)
- Maria I New
- Department of Pediatrics, Mount Sinai School of Medicine, 1 Gustave Levy Place, Box 1198, New York, NY 10029, USA.
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Freundlich M, Ludwig M. A novel epithelial sodium channel beta-subunit mutation associated with hypertensive Liddle syndrome. Pediatr Nephrol 2005; 20:512-5. [PMID: 15690192 DOI: 10.1007/s00467-004-1751-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2004] [Revised: 10/13/2004] [Accepted: 10/13/2004] [Indexed: 10/25/2022]
Abstract
Low-renin hypertension responsive to amiloride-thiazide therapy in a 4-year-old Afro-Haitian girl suggested Liddle syndrome. Urine steroid profiling substantiated the diagnosis and DNA analysis of the epithelial sodium channel (ENaC) revealed a novel heterozygous beta ENaC mutation in the patient and in her hypertensive father. Liddle syndrome should be considered as a cause of hypertension in young children particularly with suppressed renin activity.
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Zhou R, Snyder PM. Nedd4-2 phosphorylation induces serum and glucocorticoid-regulated kinase (SGK) ubiquitination and degradation. J Biol Chem 2004; 280:4518-23. [PMID: 15576372 DOI: 10.1074/jbc.m411053200] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Serum and glucocorticoid-regulated kinase (SGK) plays a key role in the regulation of epithelial Na+ transport. SGK phosphorylates Nedd4-2, an E3 ubiquitin-protein ligase that targets the epithelial Na+ channel (ENaC) for degradation. Phosphorylation increases Na+ transport by reducing Nedd4-2 binding to ENaC, which increases ENaC expression at the cell surface. Thus, SGK expression must be tightly controlled to maintain Na+ homeostasis. This occurs in part by regulation of SGK transcription; a variety of signals including steroid hormones (aldosterone and glucocorticoids) increase SGK levels by inducing transcription of SGK. However, SGK has a short half-life, suggesting that SGK levels might also be controlled by regulation of SGK degradation. Here we found that SGK degradation is mediated in part by Nedd4-2. Consistent with this model, overexpression of Nedd4-2 decreased steady-state levels of SGK in a dose-dependent manner by increasing SGK ubiquitination and degradation in the 26S proteasome. Conversely, silencing of Nedd4-2 by RNA interference stabilized SGK. Nedd4-2 phosphorylation potentiates SGK degradation; degradation was reduced by Nedd4-2 and SGK mutations that disrupt phosphorylation or by inhibition of SGK kinase activity. Together with previous work, the data support a model in which SGK and Nedd4-2 regulate one another in a reciprocal manner. SGK phosphorylates Nedd4-2, which reduces Nedd4-2 binding and inhibition of ENaC. Conversely, phosphorylation increases Nedd4-2-mediated degradation of SGK. Thus, by phosphorylating Nedd4-2, SGK induces its own degradation. This feedback inhibition may fine-tune the regulation of epithelial Na+ absorption.
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Affiliation(s)
- Ruifeng Zhou
- Department of Internal Medicine and Physiology, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA
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Snyder PM, Olson DR, Kabra R, Zhou R, Steines JC. cAMP and serum and glucocorticoid-inducible kinase (SGK) regulate the epithelial Na(+) channel through convergent phosphorylation of Nedd4-2. J Biol Chem 2004; 279:45753-8. [PMID: 15328345 DOI: 10.1074/jbc.m407858200] [Citation(s) in RCA: 177] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The epithelial Na(+) channel (ENaC) functions as a pathway for epithelial Na(+) transport, contributing to Na(+) homeostasis and blood pressure control. Vasopressin increases ENaC expression at the cell surface through a pathway that includes cAMP and cAMP-dependent protein kinase (PKA), but the mechanisms that link PKA to ENaC are unknown. Here we found that cAMP regulates Na(+) transport in part by inhibiting the function of Nedd4-2, an E3 ubiquitin-protein ligase that targets ENaC for degradation. Consistent with this model, we found that cAMP inhibited Nedd4-2 by decreasing its binding to ENaC. Moreover, decreased Nedd4-2 expression (RNA interference) or overexpression of a dominant negative Nedd4-2 construct disrupted ENaC regulation by cAMP. Nedd4-2 was a substrate for phosphorylation by PKA in vitro and in cells; three Nedd4-2 residues were phosphorylated by PKA and were required for cAMP to inhibit Nedd4-2 (relative functional importance Ser-327 > Ser-221 > Thr-246). Previous work found that these residues are also phosphorylated by serum and glucocorticoid-inducible kinase (SGK), a downstream mediator by which aldosterone regulates epithelial Na(+) transport. Consistent with a functional interaction between these pathways, overexpression of SGK blunted ENaC stimulation by cAMP, whereas inhibition of SGK increased stimulation. Conversely, cAMP agonists decreased ENaC stimulation by SGK. The data suggest that cAMP regulates ENaC in part by phosphorylation and inhibition of Nedd4-2. Moreover, Nedd4-2 is a central convergence point for kinase regulation of Na(+) transport.
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Affiliation(s)
- Peter M Snyder
- Department of Internal Medicine, and Department of Physiology and Biophysics, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA.
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Abstract
There has been a dramatic recent increase in the understanding of the renal epithelial transport systems with the identification, cloning and characterization of a large number of membrane transport proteins. The aim of this chapter is to integrate this body of knowledge with the understanding of the clinical disorders that accompany gain, loss or dysregulation of function of these transport systems. The specific focus is on the best-defined human clinical syndromes in which there are derangements in potassium (K(+)) homeostasis. The focus is on inherited syndromes, rather than on acquired syndromes due to tubular transport defects, and the therapeutic approaches address chronic derangements of K(+) homeostasis rather than acute interventions directed at life-threatening hyperkalaemia.
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Affiliation(s)
- David G Warnock
- Division of Nephrology, Departments of Medicine and Physiology, Nephrology Research and Training Center, University of Alabama at Birmingham, 647 THT, 1530 3rd Avenue South, Birmingham, AL 35294-0006, USA.
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Rayner BL, Owen EP, King JA, Soule SG, Vreede H, Opie LH, Marais D, Davidson JS. A new mutation, R563Q, of the beta subunit of the epithelial sodium channel associated with low-renin, low-aldosterone hypertension. J Hypertens 2003; 21:921-6. [PMID: 12714866 DOI: 10.1097/00004872-200305000-00016] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To determine the relationship between R563Q, a mutation of the renal epithelial sodium channel, and hypertension. METHODS Hypertensive patients with low renin and aldosterone, hypokalemia or resistant hypertension were selected for DNA analysis. Genomic DNA encoding the C-terminal domain of the epithelial sodium channel beta subunit from hypertensives and controls was amplified by polymerase chain reaction and screened for the R563Q mutation by digestion with Sfc1 restriction enzyme, or sequenced. RESULTS A previously undescribed mutation, R563Q, of the beta epithelial sodium channel was found in 10 of 139 black hypertensives, but was not present in any of 103 black normotensives, a significant (P = 0.0058) difference in frequency. The frequency of the mutation in the subgroup of black low-renin, low-aldosterone hypertensives (four of 14) was significantly (P = 0.0001) greater than in normotensives, and was also greater (P = 0.041) than in normal-high renin hypertensives, suggesting that R563Q is an activating mutation of the epithelial sodium channel. R563Q was also found in seven out of 250 mixed ancestry hypertensives, and was significantly (P = 0.017) associated with low-renin, low-aldosterone hypertension in this population group. The mutation was found in one of 100 mixed ancestry normotensives but not in any of 136 white hypertensives. Of the 18 R563Q patients, 11 had severe hypertension, leading to renal failure in two cases, while only two had hypokalaemia. CONCLUSIONS R563Q, a new variant of the beta epithelial sodium channel, is associated with low-renin, low-aldosterone hypertension, in South African black and mixed-ancestry patients. Only a minority of individuals with the R563Q allelle fully express the Liddle's syndrome phenotype.
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Affiliation(s)
- Brian L Rayner
- Departments of aMedicine and bLaboratory Medicine, Groote Schuur Hospital and University of Cape Town, South Africa
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Nakano Y, Ishida T, Ozono R, Matsuura H, Yamamoto Y, Kambe M, Chayama K, Oshima T. A frameshift mutation of beta subunit of epithelial sodium channel in a case of isolated Liddle syndrome. J Hypertens 2002; 20:2379-82. [PMID: 12473861 DOI: 10.1097/00004872-200212000-00016] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Liddle syndrome is an autosomal dominant form of salt-sensitive hypertension caused by mutations in the epithelial sodium channel expressed in the distal nephron playing an essential role in Na absorption. All reported mutations in Liddle syndrome are either missense mutations or frameshift mutations destroying the PY motif closer to the C-terminus of the beta or gamma subunits causing the situation that the epithelial sodium channels are not degraded and sodium is pooled and thus hypertension and hypokalemia are caused. METHODS We sequenced the C-terminus of the beta or gamma subunits of the epithelial sodium channel in a Japanese family of a patient clinically diagnosed as having Liddle syndrome. RESULTS As a result, we found in the proband, a frameshift mutation of the beta subunit caused by a single cytosine insertion at the codon 595, introducing a new stop codon at 605 and deleting the last 34 amino acids from the normally encoded protein. CONCLUSION This mutation is carried by neither parent (with paternity proven) and hence confirms this has occurred as a event within this family.
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Affiliation(s)
- Yukiko Nakano
- Department of Medicine and Molecular Science, Hiroshima University Graduate School of Medicine, Japan.
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Kamynina E, Staub O. Concerted action of ENaC, Nedd4-2, and Sgk1 in transepithelial Na(+) transport. Am J Physiol Renal Physiol 2002; 283:F377-87. [PMID: 12167587 DOI: 10.1152/ajprenal.00143.2002] [Citation(s) in RCA: 149] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The epithelial Na(+) channel (ENaC), located in the apical membrane of renal aldosterone-responsive epithelia, plays an essential role in controlling the Na(+) balance of extracellular fluids and hence blood pressure. As of now, ENaC is the only Na(+) transport protein for which genetic evidence exists for its involvement in the genesis of both hypertension (Liddle's syndrome) and hypotension (pseudohypoaldosteronism type 1). The regulation of ENaC involves a variety of hormonal signals (aldosterone, vasopressin, insulin), but the molecular mechanisms behind this regulation are mostly unknown. Two regulatory proteins have gained interest in recent years: the ubiquitin-protein ligase neural precursor cell-expressed, developmentally downregulated gene 4 isoform Nedd4-2, which negatively controls ENaC cell surface expression, and serum glucocorticoid-inducible kinase 1 (Sgk1), which is an aldosterone- and insulin-dependent, positive regulator of ENaC density at the plasma membrane. Here, we summarize present ideas about Sgk1 and Nedd4-2 and the lines of experimental evidence, suggesting that they act sequentially in the regulatory pathways governed by aldosterone and insulin and regulate ENaC number at the plasma membrane.
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Affiliation(s)
- Elena Kamynina
- Institute of Pharmacology and Toxicology, University of Lausanne, CH-1005 Lausanne, Switzerland
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Schafer JA. Abnormal regulation of ENaC: syndromes of salt retention and salt wasting by the collecting duct. Am J Physiol Renal Physiol 2002; 283:F221-35. [PMID: 12110505 DOI: 10.1152/ajprenal.00068.2002] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although the aldosterone-responsive segments of the nephron together reabsorb <10% of the filtered Na+, certain single-gene defects that affect the epithelial Na+ channel (ENaC) in the luminal membrane of the collecting duct (CD) or its regulation by aldosterone cause severe hypertension, whereas others cause salt wasting and hypotension. These rare defects illustrate the key role of the distal nephron in maintaining normal extracellular volume and blood pressure. Genetic defects that increase the Cl- conductance of the junctional complexes may also lead to salt retention and hypertension. Less dramatic alterations in regulatory actions of other hormones such as vasopressin (VP), either alone or with other genetic variations, diet, or environmental factors, may also produce Na+ retention or loss. Although VP acts primarily to regulate water balance, it is also an antinatriuretic hormone. Elevated basal plasma VP levels, and/or augmented VP release with increased Na+ intake, have been linked to essential hypertension in humans and in animal models of congestive heart failure and cirrhosis. Norepinephrine, dopamine, and prostaglandin E2 can inhibit the antinatriuretic effects of VP, and changes in the actions of these autocrine and paracrine regulators may also be involved in abnormal regulation of Na+ reabsorption.
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Affiliation(s)
- James A Schafer
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
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Abstract
The recent knowledge of the renal epithelial transport systems has exploded with the identification, cloning, and characterization of a large number of membrane transport proteins. The fundamental aspects of these transporters are beginning to emerge at the molecular level and are summarized in the accompanying contributions in this volume of the Annual Review of Physiology. The aim of my review is to integrate this body of knowledge with the understanding of the clinical disorders of human mineral homeostasis that accompany gain, loss, or dysregulation of function of these transport systems. The specific focus is on the best defined human clinical syndromes in which there are derangements in K(+) and Mg(2+) homeostasis.
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Affiliation(s)
- David G Warnock
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, 35294, USA.
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37
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Abstract
The epithelial Na+ channel (ENaC) forms the pathway for Na+ absorption in the kidney collecting duct and other epithelia. Dominant gain-of-function mutations cause Liddle's syndrome, an inherited form of hypertension resulting from excessive renal Na+ absorption. Conversely, loss-of-function mutations cause pseudohypoaldosteronism type I, a disorder of salt wasting and hypotension. Thus, ENaC has a critical role in the maintenance of Na+ homeostasis and blood pressure control. Altered Na+ absorption in the lung may also contribute to the pathogenesis of cystic fibrosis. Epithelial Na+ absorption is regulated in large part by mechanisms that control the expression of ENaC at the cell surface. Nedd4, a ubiquitin protein ligase, binds to ENaC and targets the channel for endocytosis and degradation. Liddle's syndrome mutations disrupt the interaction between ENaC and Nedd4, resulting in an increase in the number of ENaC channels at the cell surface. Aldosterone and vasopressin also regulate Na+ absorption to defend against hypotension and hypovolemia. Both hormones increase the expression of ENaC at the cell surface. The goal of this review is to summarize recent data on the regulation of ENaC expression at the cell surface.
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Affiliation(s)
- Peter M Snyder
- Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, 52422.
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Kyuma M, Ura N, Torii T, Takeuchi H, Takizawa H, Kitamura K, Tomita K, Sasaki S, Shimamoto K. A family with liddle's syndrome caused by a mutation in the beta subunit of the epithelial sodium channel. Clin Exp Hypertens 2001; 23:471-8. [PMID: 11478429 DOI: 10.1081/ceh-100104238] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Liddle's syndrome is a rare form of autosomal-dominant salt-sensitive hypertension. Constitutive activation of the amiloride-sensitive distal renal epithelial sodium channel (ENaC) is essential for salt-sensitive hypertension. Recently, several DNA analysis studies have indicated that there is a mutation of C-terminus of either the beta or y subunit. We sequenced the C-termini of the beta and -gamma subunits of the ENaC in a Japanese family with hypertension and hypopotassemia without excess minerarocorticoids, clinically diagnosed as Liddle's syndrome. The mutation of the ENaC of this family was beta R564X. Since such case seem to be rare in the literature, detailed data are shown in this report.
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Affiliation(s)
- M Kyuma
- The Second Department of Internal Medicine, Sapporo Medical University School of Medicine, Japan
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Gao PJ, Zhang KX, Zhu DL, He X, Han ZY, Zhan YM, Yang LW. Diagnosis of Liddle syndrome by genetic analysis of beta and gamma subunits of epithelial sodium channel--a report of five affected family members. J Hypertens 2001; 19:885-9. [PMID: 11393671 DOI: 10.1097/00004872-200105000-00008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To screen the gene mutation in beta and gamma subunits of the epithelial sodium channel (ENaC) of a Chinese family, some of whose members are clinically diagnosed as suffering from Liddle syndrome. METHODS Twelve family members were recruited to the study. Among them, two brothers had been clinically diagnosed as suffering from Liddle syndrome. Peripheral blood samples were collected from all members of the family and total genomic DNA was prepared for genetic analysis. Polymerase chain reaction (PCR) was used for amplifying the last exon of beta (codon 513-673) and gamma (codon 503-632) subunits of the ENaC gene. PCR products were purified and subjected to a direct DNA sequence analysis. RESULTS Genetic analysis of the beta ENaC gene revealed a missense mutation of CCC to CTC at codon 616 in four middle-aged men of the second generation and one young woman of the third generation. There was no mutation of the gamma ENaC gene in any of the individuals examined. CONCLUSION Through direct DNA sequencing analysis, we diagnosed the disease present in five members of a Chinese family as Liddle syndrome, and excluded it in some other young offspring suffering from the monogenic disease. Our results provide further evidence that Pro616 is a critical amino acid that has a key role in the inhibition of sodium channel activity.
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Affiliation(s)
- P J Gao
- Shanghai Institute of Hypertension, Ruijin Hospital, Shanghai Second Medical University, People's Republic of China
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Alper SL. Sporadic cases of Liddle's syndrome: Clues to essential hypertension? Am J Kidney Dis 2001. [DOI: 10.1016/s0272-6386(01)80024-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hamilton KL, Butt AG. The molecular basis of renal tubular transport disorders. Comp Biochem Physiol A Mol Integr Physiol 2000; 126:305-21. [PMID: 10964027 DOI: 10.1016/s1095-6433(00)00214-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Sodium and water homeostasis are key to the survival of organisms. Reabsorption of sodium and water occurs throughout the tubule structure of the nephron, the basic functional unit of the kidney, by various transport mechanisms. Altered transport protein function can lead to renal tubular disorders resulting in metabolic alkalosis, hypokalemia, hypertension, and decreased capacity to concentrate urine, for instance. However, recent advances in molecular physiology, molecular genetics and expression cloning systems have aided in unraveling the molecular basis of some renal tubular disorders. This review will examine the molecular basis of Bartter's syndrome, Gitelman's syndrome, Liddle's syndrome, and autosomal nephrogenic diabetes insipidus. An understanding of the molecular basis of these disorders of the human kidney can give us a better understanding of basic renal function of lower mammals and other vertebrates.
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Affiliation(s)
- K L Hamilton
- Department of Physiology, School of Medical Sciences, University of Otago, P.O. Box 913, Dunedin, New Zealand.
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Abstract
The highly amiloride-sensitive epithelial sodium channel (ENaC) is an apical membrane constituent of cells of many salt-absorbing epithelia. In the kidney, the functional relevance of ENaC expression has been well established. ENaC mediates the aldosterone-dependent sodium reabsorption in the distal nephron and is involved in the regulation of blood pressure. Mutations in genes encoding ENaC subunits are causative for two human inherited diseases: Liddle's syndrome, a severe form of hypertension associated with ENaC hyperfunction, and pseudohypoaldosteronism (PHA-1), a salt-wasting syndrome caused by decreased ENaC function. Transgenic mouse technologies provide a useful tool to study the role of ENaC in vivo. Different mouse lines have been established in which each of the ENaC subunits was affected. The phenotypes observed in these mice demonstrated that each subunit is essential for survival and for regulation of sodium transport in kidney and colon. Moreover, the alpha subunit plays a specific role in the control of fluid absorption in the airways at birth. Such mice can now be used to study the role of ENaC in various organs and can serve as models to understand the pathophysiology of these human diseases.
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Affiliation(s)
- O Bonny
- Institut de Pharmacologie et de Toxicologie, Université de Lausanne, Lausanne, Switzerland
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Stokes JB. Disorders of the epithelial sodium channel: insights into the regulation of extracellular volume and blood pressure. Kidney Int 1999; 56:2318-33. [PMID: 10594813 DOI: 10.1046/j.1523-1755.1999.00803.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- J B Stokes
- Department of Veterans Affairs Medical Center, University of Iowa, IowaCity 52242, USA
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Abstract
Our understanding of the genetics of hypertension is incomplete. A great deal has, however, been learned about the role of several <<candidate>> genes by altering their expression in transgenic and knockout models. Crosses of inbred strains, analyzed in F2 generations, have demonstrated consistent quantitative trait loci, particularly on chromosomes 1, 2 and 10, suggesting significant contributions of some genes in distinct models of rodent hypertension. The effect of these loci has been tested in congenic strains and their interaction underlined in double congenics. The weakness of testing individual animals from F2 crosses is overcome in recombinant inbred strains. In humans, Mendelian models of hypertension have contributed to progress in our understanding of this disease, but have not yet revealed any major gene of essential hypertension. Many association as well as linkage studies of humans have provided useful though somewhat contradictory data. Our renewed effort is oriented towards the discovery of genetic determinants of environmental interaction in hypertension as well as towards the future of pharmacogenomics. This progress will be the basis of future individualized treatment and prevention.
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Affiliation(s)
- P Hamet
- Centre Hospitalier de l'Université de Montréal-CHUM, Quebec, Canada
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