1
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Kunchur MG, Mauch TJ, Parkanzky M, Rahilly LJ. A review of renal tubular acidosis. J Vet Emerg Crit Care (San Antonio) 2024. [PMID: 39023331 DOI: 10.1111/vec.13407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 10/14/2022] [Accepted: 11/11/2022] [Indexed: 07/20/2024]
Abstract
OBJECTIVE To review the current scientific literature on renal tubular acidosis (RTA) in people and small animals, focusing on diseases in veterinary medicine that result in secondary RTA. DATA SOURCES Scientific reviews and original research publications on people and small animals focusing on RTA. SUMMARY RTA is characterized by defective renal acid-base regulation that results in normal anion gap hyperchloremic metabolic acidosis. Renal acid-base regulation includes the reabsorption and regeneration of bicarbonate in the renal proximal tubule and collecting ducts and the process of ammoniagenesis. RTA occurs as a primary genetic disorder or secondary to disease conditions. Based on pathophysiology, RTA is classified as distal or type 1 RTA, proximal or type 2 RTA, type 3 RTA or carbonic anhydrase II mutation, and type 4 or hyperkalemic RTA. Fanconi syndrome comprises proximal RTA with additional defects in proximal tubular function. Extensive research elucidating the genetic basis of RTA in people exists. RTA is a genetic disorder in the Basenji breed of dogs, where the mutation is known. Secondary RTA in human and veterinary medicine is the sequela of diseases that include immune-mediated, toxic, and infectious causes. Diagnosis and characterization of RTA include the measurement of urine pH and the evaluation of renal handling of substances that should affect acid or bicarbonate excretion. CONCLUSIONS Commonality exists between human and veterinary medicine among the types of RTA. Many genetic defects causing primary RTA are identified in people, but those in companion animals other than in the Basenji are unknown. Critically ill veterinary patients are often admitted to the ICU for diseases associated with secondary RTA, or they may develop RTA while hospitalized. Recognition and treatment of RTA may reverse tubular dysfunction and promote recovery by correcting metabolic acidosis.
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Affiliation(s)
| | - Teri Jo Mauch
- University of Nebraska Medical Center and Children's Hospital, Omaha, Nebraska, USA
- University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | | | - Louisa J Rahilly
- Cape Cod Veterinary Specialists, Buzzards Bay, Massachusetts, USA
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2
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Brazier F, Cornière N, Picard N, Chambrey R, Eladari D. Pendrin: linking acid base to blood pressure. Pflugers Arch 2024; 476:533-543. [PMID: 38110744 DOI: 10.1007/s00424-023-02897-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 12/11/2023] [Accepted: 12/11/2023] [Indexed: 12/20/2023]
Abstract
Pendrin (SLC26A4) is an anion exchanger from the SLC26 transporter family which is mutated in human patients affected by Pendred syndrome, an autosomal recessive disease characterized by sensoneurinal deafness and hypothyroidism. Pendrin is also expressed in the kidney where it mediates the exchange of internal HCO3- for external Cl- at the apical surface of renal type B and non-A non-B-intercalated cells. Studies using pendrin knockout mice have first revealed that pendrin is essential for renal base excretion. However, subsequent studies have demonstrated that pendrin also controls chloride absorption by the distal nephron and that this mechanism is critical for renal NaCl balance. Furthermore, pendrin has been shown to control vascular volume and ultimately blood pressure. This review summarizes the current knowledge about how pendrin is linking renal acid-base regulation to blood pressure control.
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Affiliation(s)
- François Brazier
- Centre de dépistage et de Médecine de précision des Maladies Rénales, Service de Néphrologie, Centre Hospitalier Universitaire Amiens-Picardie, Université de Picardie Jules Verne, F-80000, Amiens, France
| | - Nicolas Cornière
- Centre de dépistage et de Médecine de précision des Maladies Rénales, Service de Néphrologie, Centre Hospitalier Universitaire Amiens-Picardie, Université de Picardie Jules Verne, F-80000, Amiens, France
| | - Nicolas Picard
- Laboratory of Tissue Biology and Therapeutic Engineering, UMR 5305 CNRS, University Lyon 1, Lyon, France
| | - Régine Chambrey
- Paris Cardiovascular Research Center (PARCC), INSERM U970, F-75015, Paris, France
| | - Dominique Eladari
- Centre de dépistage et de Médecine de précision des Maladies Rénales, Service de Néphrologie, Centre Hospitalier Universitaire Amiens-Picardie, Université de Picardie Jules Verne, F-80000, Amiens, France.
- Laboratory of Tissue Biology and Therapeutic Engineering, UMR 5305 CNRS, University Lyon 1, Lyon, France.
- French Clinical Research Infrastructure Network (F-CRIN): INI-CRCT, Vandœuvre-lès-Nancy, France.
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3
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Wang L, Hoang A, Gil-Iturbe E, Laganowsky A, Quick M, Zhou M. Mechanism of anion exchange and small-molecule inhibition of pendrin. Nat Commun 2024; 15:346. [PMID: 38184688 PMCID: PMC10771415 DOI: 10.1038/s41467-023-44612-1] [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: 06/24/2023] [Accepted: 12/21/2023] [Indexed: 01/08/2024] Open
Abstract
Pendrin (SLC26A4) is an anion exchanger that mediates bicarbonate (HCO3-) exchange for chloride (Cl-) and is crucial for maintaining pH and salt homeostasis in the kidney, lung, and cochlea. Pendrin also exports iodide (I-) in the thyroid gland. Pendrin mutations in humans lead to Pendred syndrome, causing hearing loss and goiter. Inhibition of pendrin is a validated approach for attenuating airway hyperresponsiveness in asthma and for treating hypertension. However, the mechanism of anion exchange and its inhibition by drugs remains poorly understood. We applied cryo-electron microscopy to determine structures of pendrin from Sus scrofa in the presence of either Cl-, I-, HCO3- or in the apo-state. The structures reveal two anion-binding sites in each protomer, and functional analyses show both sites are involved in anion exchange. The structures also show interactions between the Sulfate Transporter and Anti-Sigma factor antagonist (STAS) and transmembrane domains, and mutational studies suggest a regulatory role. We also determine the structure of pendrin in a complex with niflumic acid (NFA), which uncovers a mechanism of inhibition by competing with anion binding and impeding the structural changes necessary for anion exchange. These results reveal directions for understanding the mechanisms of anion selectivity and exchange and their regulations by the STAS domain. This work also establishes a foundation for analyzing the pathophysiology of mutations associated with Pendred syndrome.
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Affiliation(s)
- Lie Wang
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
| | - Anthony Hoang
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
| | - Eva Gil-Iturbe
- Department of Psychiatry, Columbia University Irving Medical Center, New York, NY, USA
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, USA
| | - Arthur Laganowsky
- Department of Chemistry, Texas A&M University, College Station, TX, USA
| | - Matthias Quick
- Department of Psychiatry, Columbia University Irving Medical Center, New York, NY, USA.
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, USA.
- Area Neuroscience - Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, USA.
| | - Ming Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA.
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4
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Geertsma ER, Oliver D. SLC26 Anion Transporters. Handb Exp Pharmacol 2024; 283:319-360. [PMID: 37947907 DOI: 10.1007/164_2023_698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
Solute carrier family 26 (SLC26) is a family of functionally diverse anion transporters found in all kingdoms of life. Anions transported by SLC26 proteins include chloride, bicarbonate, and sulfate, but also small organic dicarboxylates such as fumarate and oxalate. The human genome encodes ten functional homologs, several of which are causally associated with severe human diseases, highlighting their physiological importance. Here, we review novel insights into the structure and function of SLC26 proteins and summarize the physiological relevance of human members.
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Affiliation(s)
- Eric R Geertsma
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, Marburg, Germany.
- Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Marburg, Giessen, Germany.
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5
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Feng Y, Hu S, Zhao S, Chen M. Recent advances in genetic etiology of non-syndromic deafness in children. Front Neurosci 2023; 17:1282663. [PMID: 37928735 PMCID: PMC10620706 DOI: 10.3389/fnins.2023.1282663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 10/04/2023] [Indexed: 11/07/2023] Open
Abstract
Congenital auditory impairment is a prevalent anomaly observed in approximately 2-3 per 1,000 infants. The consequences associated with hearing loss among children encompass the decline of verbal communication, linguistic skills, educational progress, social integration, cognitive aptitude, and overall well-being. Approaches to reversing or preventing genetic hearing loss are limited. Patients with mild and moderate hearing loss can only use hearing aids, while those with severe hearing loss can only acquire speech and language through cochlear implants. Both environmental and genetic factors contribute to the occurrence of congenital hearing loss, and advancements in our understanding of the pathophysiology and molecular mechanisms underlying hearing loss, coupled with recent progress in genetic testing techniques, will facilitate the development of innovative approaches for treatment and screening. In this paper, the latest research progress in genetic etiology of non-syndromic deafness in children with the highest incidence is summarized in order to provide help for personalized diagnosis and treatment of deafness in children.
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6
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Liu Q, Zhang X, Huang H, Chen Y, Wang F, Hao A, Zhan W, Mao Q, Hu Y, Han L, Sun Y, Zhang M, Liu Z, Li GL, Zhang W, Shu Y, Sun L, Chen Z. Asymmetric pendrin homodimer reveals its molecular mechanism as anion exchanger. Nat Commun 2023; 14:3012. [PMID: 37230976 DOI: 10.1038/s41467-023-38303-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 04/23/2023] [Indexed: 05/27/2023] Open
Abstract
Pendrin (SLC26A4) is an anion exchanger expressed in the apical membranes of selected epithelia. Pendrin ablation causes Pendred syndrome, a genetic disorder associated with sensorineural hearing loss, hypothyroid goiter, and reduced blood pressure. However its molecular structure has remained unknown, limiting our understanding of the structural basis of transport. Here, we determine the cryo-electron microscopy structures of mouse pendrin with symmetric and asymmetric homodimer conformations. The asymmetric homodimer consists of one inward-facing protomer and the other outward-facing protomer, representing coincident uptake and secretion- a unique state of pendrin as an electroneutral exchanger. The multiple conformations presented here provide an inverted alternate-access mechanism for anion exchange. The structural and functional data presented here disclose the properties of an anion exchange cleft and help understand the importance of disease-associated variants, which will shed light on the pendrin exchange mechanism.
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Affiliation(s)
- Qianying Liu
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Xiang Zhang
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Hui Huang
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Yuxin Chen
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
| | - Fang Wang
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
| | - Aihua Hao
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Wuqiang Zhan
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Qiyu Mao
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Yuxia Hu
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Lin Han
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Yifang Sun
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Meng Zhang
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Zhimin Liu
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Geng-Lin Li
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
| | - Weijia Zhang
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Yilai Shu
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China.
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China.
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China.
- Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China.
| | - Lei Sun
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China.
- Shanghai Institute of Infectious Disease and Biosecurity, Shanghai, 200032, China.
- Shanghai Key Laboratory of Medical Epigenetics, Shanghai, 200032, China.
| | - Zhenguo Chen
- The Fifth People's Hospital of Shanghai and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China.
- Shanghai Institute of Infectious Disease and Biosecurity, Shanghai, 200032, China.
- Shanghai Key Laboratory of Medical Epigenetics, Shanghai, 200032, China.
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7
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Tahaei E, Pham TD, Al-Qusairi L, Grimm R, Wall SM, Welling PA. Pendrin regulation is prioritized by anion in high-potassium diets. Am J Physiol Renal Physiol 2023; 324:F256-F266. [PMID: 36656986 PMCID: PMC9942896 DOI: 10.1152/ajprenal.00128.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 12/21/2022] [Accepted: 01/16/2023] [Indexed: 01/20/2023] Open
Abstract
The Cl-/[Formula: see text] exchanger pendrin in the kidney maintains acid-base balance and intravascular volume. Pendrin is upregulated in models associated with high circulating aldosterone concentration, such as dietary NaCl restriction or an aldosterone infusion. However, it has not been established if pendrin is similarly regulated by aldosterone with a high-K+ diet because the effects of accompanying anions have not been considered. Here, we explored how pendrin is modulated by different dietary potassium salts. Wild-type (WT) and aldosterone synthase (AS) knockout (KO) mice were randomized to control, high-KHCO3, or high-KCl diets. Dietary KCl and KHCO3 loading increased aldosterone in WT mice to the same extent but had opposite effects on pendrin abundance. KHCO3 loading increased pendrin protein and transcript abundance. Conversely, high-KCl diet feeding caused pendrin to decrease within 8 h of switching from the high-KHCO3 diet, coincident with an increase in plasma Cl- and a decrease in [Formula: see text]. In contrast, switching the high-KCl diet to the high-KHCO3 diet caused pendrin to increase in WT mice. Experiments in AS KO mice revealed that aldosterone is necessary to optimally upregulate pendrin protein in response to the high-KHCO3 diet but not to increase pendrin mRNA. We conclude that pendrin is differentially regulated by different dietary potassium salts and that its regulation is prioritized by the dietary anion, providing a mechanism to prevent metabolic alkalosis with high-K+ base diets and safeguard against hyperchloremic acidosis with consumption of high-KCl diets.NEW & NOTEWORTHY Regulation of the Cl-/[Formula: see text] exchanger pendrin has been suggested to explain the aldosterone paradox. A high-K+ diet has been proposed to downregulate a pendrin-mediated K+-sparing NaCl reabsorption pathway to maximize urinary K+ excretion. Here, we challenged the hypothesis, revealing that the accompanying anion, not K+, drives pendrin expression. Pendrin is downregulated with a high-KCl diet, preventing acidosis, and upregulated with an alkaline-rich high-K+ diet, preventing metabolic alkalosis. Pendrin regulation is prioritized for acid-base balance.
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Affiliation(s)
- Ebrahim Tahaei
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Truyen D Pham
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Lama Al-Qusairi
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Rick Grimm
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Susan M Wall
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Paul A Welling
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
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8
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Lu YT, Wang L, Hou LL, Zheng PP, Xu Q, Deng DT. SLC26A4 mutation in Pendred syndrome with hypokalemia: A case report. Medicine (Baltimore) 2022; 101:e30253. [PMID: 36107570 PMCID: PMC9439793 DOI: 10.1097/md.0000000000030253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
RATIONALE Pendred syndrome is an autosomal recessive disorder characterized by sensorineural hearing loss, inner ear malformations, goiter, and abnormal organification of iodide. It is caused by mutations in SLC26A4 gene, which encodes pendrin (a transporter of chloride, bicarbonate, and iodide). Pendred syndrome is a common cause of syndromic deafness, but the metabolic abnormalities it causes are often overlooked. Here, we report the case of a patient diagnosed with Pendred syndrome with hypokalemia. PATIENT CONCERNS A 53-year-old deaf-mute woman was hospitalized due to severe limb asthenia. The emergency examination showed that her blood potassium level was 1.8 mmol/L. DIAGNOSES Through the genetic test, we found a mutation of SLC26A4 gene in NM_000441: c.2027T>A, p.L676Q, as well as the SLC26A4 exon 5-6 deletion. These genetic variations pointed to Pendred syndrome (an autosomal recessive disorder that mainly affects the inner ear, thyroid, and kidney) which is a common cause of syndromic deafness. INTERVENTIONS The patient was treated with potassium supplements and screened for the cause of hypokalemia. OUTCOMES The patient was discharged after her potassium levels rose to the normal range. LESSONS Patients with Pendred syndrome may also have certain metabolic abnormalities; thus, more attention should be paid to them during clinical diagnosis.
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Affiliation(s)
- Ya-Ting Lu
- Department of Endocrinology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui Province, China
| | - Lin Wang
- Department of Endocrinology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui Province, China
| | - Le-Le Hou
- Department of Endocrinology, Zhongda Hospital, Medical School, Southeast University, Nanjing, Jiangsu Province, China
| | - Ping-Ping Zheng
- Department of Endocrinology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui Province, China
| | - Qian Xu
- Department of Endocrinology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui Province, China
| | - Da-Tong Deng
- Department of Endocrinology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui Province, China
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9
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He X, Zhao S, Shi L, Lu Y, Yang Y, Zhang X. Compound heterozygous variants of the SLC26A4 gene in a Chinese family with enlarged vestibular aqueducts. BMC Med Genomics 2022; 15:152. [PMID: 35804348 PMCID: PMC9270741 DOI: 10.1186/s12920-022-01271-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 05/10/2022] [Indexed: 11/21/2022] Open
Abstract
Background To investigate the genetic causes of hearing loss in patients with enlarged vestibular aqueduct (EVA), the SLC26A4-related genotypes and phenotypes were analyzed. SLC26A4 gene is closely associated with EVA and its homozygous mutations or compound heterozygous mutations may cause deafness and strongly affect quality of life. Methods The patients who came to our hospital for hearing test and accompanied by bilateral hearing abnormalities were collected for fifteen deafness-related gene mutations detection. Those who are positive will be verified by Sanger sequencing, combined with family history, hearing test, and computerized tomography (CT) of the temporal bone, aiming to diagnose the enlarged vestibular aqueducts. Whole-exome sequencing were performed when necessary. Results Our patient failed hearing screening on both sides twice, and EVA (> 1.5 mm) was diagnosed by CT. This study has identified a novel missense mutation in the SLC26A4 gene, c.2069T>A, which in compound heterozygosity with c.1174A>T is likely to be the cause of hearing loss. The novel heterozygous c.2069T>A mutation of SLC26A4 gene has been submitted to Clinvar with Variation ID 1,048,780. Conclusion Our findings expand the gene mutation spectrum of SLC26A4 and provide additional knowledge for diagnosis and genetic counseling associated with EVA-induced hearing loss. Supplementary Information The online version contains supplementary material available at 10.1186/s12920-022-01271-3.
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Affiliation(s)
- Xiaohui He
- Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, China
| | - Shaozhi Zhao
- Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, China
| | - Lin Shi
- Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, China
| | - Yitong Lu
- Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, China
| | - Yintong Yang
- Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, China
| | - Xinwen Zhang
- Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, China.
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10
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Early Elevation and Normalization of Electrode Impedance in Patients With Enlarged Vestibular Aqueduct Undergoing Cochlear Implantation. Otol Neurotol 2022; 43:e535-e539. [PMID: 35213479 DOI: 10.1097/mao.0000000000003506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To characterize early changes in impedance in patients undergoing cochlear implantation with and without enlarged vestibular aqueducts (EVA). METHODS Case-control retrospective study of patients undergoing cochlear implantation with and without EVA. Impedance was measured across all channels intraoperatively and within 24 hours of surgery. All patients received the same electrode array. RESULTS Ten patients with EVA (and matched controls were identified). The average intraoperative impedance across all electrodes was significantly higher in patients with EVA (13.1 ± 1.4 kΩ) than in controls (9.6 ± 2.5 kΩ, p < 0.001). At 24-hour activation, the average impedance across all electrodes was roughly equal in both groups (6.8 ± 2.7 kΩ versus 6.5 ± 2.1 kΩ, p = 0.72). CONCLUSIONS This study is the first identify differences in intraoperative impedance between patients with and without EVA. In addition, these data demonstrate rapid normalization within 24 hours of surgery. Such findings can give a window of insight into both the intracochlear microenvironment of patients with EVA and the important early electrode-fluid-tissue interface changes that occur within hours of surgery for all patients.
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11
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Feng P, Xu Z, Chen J, Liu M, Zhao Y, Wang D, Han L, Wang L, Wan B, Xu X, Li D, Shu Y, Hua Y. Rescue of mis-splicing of a common SLC26A4 mutant associated with sensorineural hearing loss by antisense oligonucleotides. MOLECULAR THERAPY - NUCLEIC ACIDS 2022; 28:280-292. [PMID: 35433113 PMCID: PMC8987850 DOI: 10.1016/j.omtn.2022.03.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 03/18/2022] [Indexed: 11/11/2022]
Abstract
A wide spectrum of SLC26A4 mutations causes Pendred syndrome and enlarged vestibular aqueduct, both associated with sensorineural hearing loss (SNHL). A splice-site mutation, c.919-2A>G (A-2G), which is common in Asian populations, impairs the 3′ splice site of intron 7, resulting in exon 8 skipping during pre-mRNA splicing and a subsequent frameshift that creates a premature termination codon in the following exon. Currently, there is no effective drug treatment for SHNL. For A-2G-triggered SNHL, molecules that correct mis-splicing of the mutant hold promise to treat the disease. Antisense oligonucleotides (ASOs) can promote exon inclusion when targeting specific splicing silencers. Here, we systematically screened a large number of ASOs in a minigene system and identified a few that markedly repressed exon 8 skipping. A lead ASO, which targets a heterogeneous nuclear ribonucleoprotein (hnRNP) A1/A2 intronic splicing silencer (ISS) in intron 8, promoted efficient exon 8 inclusion in cultured peripheral blood mononuclear cells derived from two homozygous patients. In a partially humanized Slc26a4 A-2G mouse model, two subcutaneous injections of the ASO at 160 mg/kg significantly rescued exon 8 splicing in the liver. Our results demonstrate that the ISS-targeting ASO has therapeutic potential to treat genetic hearing loss caused by the A-2G mutation in SLC26A4.
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12
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Imenez Silva PH, Mohebbi N. Kidney metabolism and acid-base control: back to the basics. Pflugers Arch 2022; 474:919-934. [PMID: 35513635 PMCID: PMC9338915 DOI: 10.1007/s00424-022-02696-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 01/18/2023]
Abstract
Kidneys are central in the regulation of multiple physiological functions, such as removal of metabolic wastes and toxins, maintenance of electrolyte and fluid balance, and control of pH homeostasis. In addition, kidneys participate in systemic gluconeogenesis and in the production or activation of hormones. Acid-base conditions influence all these functions concomitantly. Healthy kidneys properly coordinate a series of physiological responses in the face of acute and chronic acid-base disorders. However, injured kidneys have a reduced capacity to adapt to such challenges. Chronic kidney disease patients are an example of individuals typically exposed to chronic and progressive metabolic acidosis. Their organisms undergo a series of alterations that brake large detrimental changes in the homeostasis of several parameters, but these alterations may also operate as further drivers of kidney damage. Acid-base disorders lead not only to changes in mechanisms involved in acid-base balance maintenance, but they also affect multiple other mechanisms tightly wired to it. In this review article, we explore the basic renal activities involved in the maintenance of acid-base balance and show how they are interconnected to cell energy metabolism and other important intracellular activities. These intertwined relationships have been investigated for more than a century, but a modern conceptual organization of these events is lacking. We propose that pH homeostasis indissociably interacts with central pathways that drive progression of chronic kidney disease, such as inflammation and metabolism, independent of etiology.
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Affiliation(s)
- Pedro Henrique Imenez Silva
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
- National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland.
| | - Nilufar Mohebbi
- National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
- Praxis Und Dialysezentrum Zurich, Zurich, Switzerland
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13
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Xu J, Barone S, Varasteh Kia M, Holliday LS, Zahedi K, Soleimani M. Identification of IQGAP1 as a SLC26A4 (Pendrin)-Binding Protein in the Kidney. Front Mol Biosci 2022; 9:874186. [PMID: 35601831 PMCID: PMC9117723 DOI: 10.3389/fmolb.2022.874186] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 03/22/2022] [Indexed: 11/25/2022] Open
Abstract
Background: Several members of the SLC26A family of transporters, including SLC26A3 (DRA), SLC26A5 (prestin), SLC26A6 (PAT-1; CFEX) and SLC26A9, form multi-protein complexes with a number of molecules (e.g., cytoskeletal proteins, anchoring or adaptor proteins, cystic fibrosis transmembrane conductance regulator, and protein kinases). These interactions provide regulatory signals for these molecules. However, the identity of proteins that interact with the Cl-/HCO3 - exchanger, SLC26A4 (pendrin), have yet to be determined. The purpose of this study is to identify the protein(s) that interact with pendrin. Methods: A yeast two hybrid (Y2H) system was employed to screen a mouse kidney cDNA library using the C-terminal fragment of SLC26A4 as bait. Immunofluorescence microscopic examination of kidney sections, as well as co-immunoprecipitation assays, were performed using affinity purified antibodies and kidney protein extracts to confirm the co-localization and interaction of pendrin and the identified binding partners. Co-expression studies were carried out in cultured cells to examine the effect of binding partners on pendrin trafficking and activity. Results: The Y2H studies identified IQ motif-containing GTPase-activating protein 1 (IQGAP1) as a protein that binds to SLC26A4's C-terminus. Co-immunoprecipitation experiments using affinity purified anti-IQGAP1 antibodies followed by western blot analysis of kidney protein eluates using pendrin-specific antibodies confirmed the interaction of pendrin and IQGAP1. Immunofluorescence microscopy studies demonstrated that IQGAP1 co-localizes with pendrin on the apical membrane of B-intercalated cells, whereas it shows basolateral expression in A-intercalated cells in the cortical collecting duct (CCD). Functional and confocal studies in HEK-293 cells, as well as confocal studies in MDCK cells, demonstrated that the co-transfection of pendrin and IQGAP1 shows strong co-localization of the two molecules on the plasma membrane along with enhanced Cl-/HCO3 - exchanger activity. Conclusion: IQGAP1 was identified as a protein that binds to the C-terminus of pendrin in B-intercalated cells. IQGAP1 co-localized with pendrin on the apical membrane of B-intercalated cells. Co-expression of IQGAP1 with pendrin resulted in strong co-localization of the two molecules and increased the activity of pendrin in the plasma membrane in cultured cells. We propose that pendrin's interaction with IQGAP1 may play a critical role in the regulation of CCD function and physiology, and that disruption of this interaction could contribute to altered pendrin trafficking and/or activity in pathophysiologic states.
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Affiliation(s)
- Jie Xu
- Research Services, VA Medical Center, Albuquerque, NM, United States,Department of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Sharon Barone
- Research Services, VA Medical Center, Albuquerque, NM, United States,Department of Medicine, University of Cincinnati, Cincinnati, OH, United States,Department of Medicine, University of New Mexico, Albuquerque, NM, United States
| | - Mujan Varasteh Kia
- Department of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - L. Shannon Holliday
- Department of Orthodontics, University of Florida, Gainesville, FL, United States
| | - Kamyar Zahedi
- Research Services, VA Medical Center, Albuquerque, NM, United States,Department of Medicine, University of Cincinnati, Cincinnati, OH, United States,Department of Medicine, University of New Mexico, Albuquerque, NM, United States
| | - Manoocher Soleimani
- Research Services, VA Medical Center, Albuquerque, NM, United States,Department of Medicine, University of Cincinnati, Cincinnati, OH, United States,Department of Medicine, University of New Mexico, Albuquerque, NM, United States,*Correspondence: Manoocher Soleimani,
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14
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Abstract
PURPOSE OF REVIEW Pendrin resides on the luminal membrane of type B intercalated cells in the renal collecting tubule system mediating the absorption of chloride in exchange for bicarbonate. In mice or humans lacking pendrin, blood pressure is lower, and pendrin knockout mice are resistant to aldosterone-induced hypertension. Here we discuss recent findings on the regulation of pendrin. RECENT FINDINGS Pendrin activity is stimulated during alkalosis partly mediated by secretin. Also, angiotensin II and aldosterone stimulate pendrin activity requiring the mineralocorticoid receptor in intercalated cells. Angiotensin II induces dephosphorylation of the mineralocorticoid receptor rendering the receptor susceptible for aldosterone binding. In the absence of the mineralocorticoid receptor in intercalated cells, angiotensin II does not stimulate pendrin. The effect of aldosterone on pendrin expression is in part mediated by the development of hypokalemic alkalosis and blunted by K-supplements or amiloride. Part of the blood pressure-increasing effect of pendrin is also mediated by its stimulatory effect on the epithelial Na-channel in neighbouring principal cells. SUMMARY These findings identify pendrin as a critical regulator of renal salt handling and blood pressure along with acid--base balance. A regulatory network of hormones fine-tuning activity is emerging. Drugs blocking pendrin are being developed.
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15
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Sudarikova A, Vasileva V, Sultanova R, Ilatovskaya D. Recent advances in understanding ion transport mechanisms in polycystic kidney disease. Clin Sci (Lond) 2021; 135:2521-2540. [PMID: 34751394 PMCID: PMC8589009 DOI: 10.1042/cs20210370] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 10/15/2021] [Accepted: 10/26/2021] [Indexed: 12/18/2022]
Abstract
This review focuses on the most recent advances in the understanding of the electrolyte transport-related mechanisms important for the development of severe inherited renal disorders, autosomal dominant (AD) and recessive (AR) forms of polycystic kidney disease (PKD). We provide here a basic overview of the origins and clinical aspects of ARPKD and ADPKD and discuss the implications of electrolyte transport in cystogenesis. Special attention is devoted to intracellular calcium handling by the cystic cells, with a focus on polycystins and fibrocystin, as well as other calcium level regulators, such as transient receptor potential vanilloid type 4 (TRPV4) channels, ciliary machinery, and purinergic receptor remodeling. Sodium transport is reviewed with a focus on the epithelial sodium channel (ENaC), and the role of chloride-dependent fluid secretion in cystic fluid accumulation is discussed. In addition, we highlight the emerging promising concepts in the field, such as potassium transport, and suggest some new avenues for research related to electrolyte handling.
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Affiliation(s)
| | | | - Regina F. Sultanova
- Saint-Petersburg State Chemical Pharmaceutical University, St. Petersburg, Russia
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16
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Rehman T, Karp PH, Tan P, Goodell BJ, Pezzulo AA, Thurman AL, Thornell IM, Durfey SL, Duffey ME, Stoltz DA, McKone EF, Singh PK, Welsh MJ. Inflammatory cytokines TNF-α and IL-17 enhance the efficacy of cystic fibrosis transmembrane conductance regulator modulators. J Clin Invest 2021; 131:e150398. [PMID: 34166230 DOI: 10.1172/jci150398] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 06/22/2021] [Indexed: 12/12/2022] Open
Abstract
Without cystic fibrosis transmembrane conductance regulator-mediated (CFTR-mediated) HCO3- secretion, airway epithelia of newborns with cystic fibrosis (CF) produce an abnormally acidic airway surface liquid (ASL), and the decreased pH impairs respiratory host defenses. However, within a few months of birth, ASL pH increases to match that in non-CF airways. Although the physiological basis for the increase is unknown, this time course matches the development of inflammation in CF airways. To learn whether inflammation alters CF ASL pH, we treated CF epithelia with TNF-α and IL-17 (TNF-α+IL-17), 2 inflammatory cytokines that are elevated in CF airways. TNF-α+IL-17 markedly increased ASL pH by upregulating pendrin, an apical Cl-/HCO3- exchanger. Moreover, when CF epithelia were exposed to TNF-α+IL-17, clinically approved CFTR modulators further alkalinized ASL pH. As predicted by these results, in vivo data revealed a positive correlation between airway inflammation and CFTR modulator-induced improvement in lung function. These findings suggest that inflammation is a key regulator of HCO3- secretion in CF airways. Thus, they explain earlier observations that ASL pH increases after birth and indicate that, for similar levels of inflammation, the pH of CF ASL is abnormally acidic. These results also suggest that a non-cell-autonomous mechanism, airway inflammation, is an important determinant of the response to CFTR modulators.
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Affiliation(s)
- Tayyab Rehman
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine and
| | - Philip H Karp
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine and.,Howard Hughes Medical Institute, University of Iowa, Iowa City, Iowa, USA
| | - Ping Tan
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine and
| | - Brian J Goodell
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine and
| | - Alejandro A Pezzulo
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine and
| | - Andrew L Thurman
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine and
| | - Ian M Thornell
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine and
| | - Samantha L Durfey
- Departments of Medicine and Microbiology, University of Washington, Seattle, Washington, USA
| | - Michael E Duffey
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA
| | - David A Stoltz
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine and.,Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Edward F McKone
- National Referral Centre for Adult Cystic Fibrosis, St. Vincent's University Hospital and University College Dublin School of Medicine, Dublin, Ireland
| | - Pradeep K Singh
- Departments of Medicine and Microbiology, University of Washington, Seattle, Washington, USA
| | - Michael J Welsh
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine and.,Howard Hughes Medical Institute, University of Iowa, Iowa City, Iowa, USA.,Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
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17
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Horiguchi G, Matsumoto K, Nemoto K, Inokuchi M, Hirotsu N. Transition From Proto-Kranz-Type Photosynthesis to HCO 3 - Use Photosynthesis in the Amphibious Plant Hygrophila polysperma. FRONTIERS IN PLANT SCIENCE 2021; 12:675507. [PMID: 34220895 PMCID: PMC8242947 DOI: 10.3389/fpls.2021.675507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 04/26/2021] [Indexed: 06/13/2023]
Abstract
Hygrophila polysperma is a heterophyllous amphibious plant. The growth of H. polysperma in submerged conditions is challenging due to the low CO2 environment, increased resistance to gas diffusion, and bicarbonate ion (HCO3 -) being the dominant dissolved inorganic carbon source. The submerged leaves of H. polysperma have significantly higher rates of underwater photosynthesis compared with the terrestrial leaves. 4,4'-Diisothiocyanatostilbene-2,2'-disulfonate (DIDS), an anion exchanger protein inhibitor, and ethoxyzolamide (EZ), an inhibitor of internal carbonic anhydrase, repressed underwater photosynthesis by the submerged leaves. These results suggested that H. polysperma acclimates to the submerged condition by using HCO3 - for photosynthesis. H. polysperma transports HCO3 - into the leaf by a DIDS-sensitive HCO3 - transporter and converted to CO2 by carbonic anhydrase. Additionally, proteome analysis revealed that submerged leaves accumulated fewer proteins associated with C4 photosynthesis compared with terrestrial leaves. This finding suggested that H. polysperma is capable of C4 and C3 photosynthesis in the terrestrial and submerged leaves, respectively. The ratio of phosphoenol pyruvate carboxylase to ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) in the submerged leaves was less than that in the terrestrial leaves. Upon anatomical observation, the terrestrial leaves exhibited a phenotype similar to the Kranz anatomy found among C4 plants; however, chloroplasts in the bundle sheath cells were not located adjacent to the vascular bundles, and the typical Kranz anatomy was absent in submerged leaves. These results suggest that H. polysperma performs proto-Kranz type photosynthesis in a terrestrial environment and shifts from a proto-Kranz type in terrestrial leaves to a HCO3 - use photosynthesis in the submerged environments.
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Affiliation(s)
- Genki Horiguchi
- Graduate School of Life Sciences, Toyo University, Gunma, Japan
| | | | - Kyosuke Nemoto
- Graduate School of Life Sciences, Toyo University, Gunma, Japan
| | - Mayu Inokuchi
- Faculty of Life Sciences, Toyo University, Gunma, Japan
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Naoki Hirotsu
- Graduate School of Life Sciences, Toyo University, Gunma, Japan
- Faculty of Life Sciences, Toyo University, Gunma, Japan
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18
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Slavney AJ, Kawakami T, Jensen MK, Nelson TC, Sams AJ, Boyko AR. Five genetic variants explain over 70% of hair coat pheomelanin intensity variation in purebred and mixed breed domestic dogs. PLoS One 2021; 16:e0250579. [PMID: 34043658 PMCID: PMC8158882 DOI: 10.1371/journal.pone.0250579] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 04/08/2021] [Indexed: 11/19/2022] Open
Abstract
In mammals, the pigment molecule pheomelanin confers red and yellow color to hair, and the intensity of this coloration is caused by variation in the amount of pheomelanin. Domestic dogs exhibit a wide range of pheomelanin intensity, ranging from the white coat of the Samoyed to the deep red coat of the Irish Setter. While several genetic variants have been associated with specific coat intensity phenotypes in certain dog breeds, they do not explain the majority of phenotypic variation across breeds. In order to gain further insight into the extent of multigenicity and epistatic interactions underlying coat pheomelanin intensity in dogs, we leveraged a large dataset obtained via a direct-to-consumer canine genetic testing service. This consisted of genome-wide single nucleotide polymorphism (SNP) genotype data and owner-provided photos for 3,057 pheomelanic mixed breed and purebred dogs from 63 breeds and varieties spanning the full range of canine coat pheomelanin intensity. We first performed a genome-wide association study (GWAS) on 2,149 of these dogs to search for additional genetic variants that underlie intensity variation. GWAS identified five loci significantly associated with intensity, of which two (CFA15 29.8 Mb and CFA20 55.8 Mb) replicate previous findings and three (CFA2 74.7 Mb, CFA18 12.9 Mb, CFA21 10.9 Mb) have not previously been reported. In order to assess the combined predictive power of these loci across dog breeds, we used our GWAS data set to fit a linear model, which explained over 70% of variation in coat pheomelanin intensity in an independent validation dataset of 908 dogs. These results introduce three novel pheomelanin intensity loci, and further demonstrate the multigenic nature of coat pheomelanin intensity determination in domestic dogs.
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Affiliation(s)
- Andrea J. Slavney
- Embark Veterinary, Inc., Boston, Massachusetts, United States of America
| | - Takeshi Kawakami
- Embark Veterinary, Inc., Boston, Massachusetts, United States of America
| | - Meghan K. Jensen
- Embark Veterinary, Inc., Boston, Massachusetts, United States of America
| | - Thomas C. Nelson
- Embark Veterinary, Inc., Boston, Massachusetts, United States of America
| | - Aaron J. Sams
- Embark Veterinary, Inc., Boston, Massachusetts, United States of America
| | - Adam R. Boyko
- Embark Veterinary, Inc., Boston, Massachusetts, United States of America
- Department of Biomedical Sciences, Cornell University College of Veterinary Medicine, Ithaca, New York, United States of America
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19
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Berg P, Svendsen SL, Sorensen MV, Larsen CK, Andersen JF, Jensen-Fangel S, Jeppesen M, Schreiber R, Cabrita I, Kunzelmann K, Leipziger J. Impaired Renal HCO 3 - Excretion in Cystic Fibrosis. J Am Soc Nephrol 2020; 31:1711-1727. [PMID: 32703846 DOI: 10.1681/asn.2020010053] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 04/13/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Patients with cystic fibrosis (CF) do not respond with increased urinary HCO3 - excretion after stimulation with secretin and often present with metabolic alkalosis. METHODS By combining RT-PCR, immunohistochemistry, isolated tubule perfusion, in vitro cell studies, and in vivo studies in different mouse models, we elucidated the mechanism of secretin-induced urinary HCO3 - excretion. For CF patients and CF mice, we developed a HCO3 - drinking test to assess the role of the cystic fibrosis transmembrane conductance regulator (CFTR) in urinary HCO3 -excretion and applied it in the patients before and after treatment with the novel CFTR modulator drug, lumacaftor-ivacaftor. RESULTS β-Intercalated cells express basolateral secretin receptors and apical CFTR and pendrin. In vivo application of secretin induced a marked urinary alkalization, an effect absent in mice lacking pendrin or CFTR. In perfused cortical collecting ducts, secretin stimulated pendrin-dependent Cl-/HCO3 - exchange. In collecting ducts in CFTR knockout mice, baseline pendrin activity was significantly lower and not responsive to secretin. Notably, patients with CF (F508del/F508del) and CF mice showed a greatly attenuated or absent urinary HCO3 --excreting ability. In patients, treatment with the CFTR modulator drug lumacaftor-ivacaftor increased the renal ability to excrete HCO3 -. CONCLUSIONS These results define the mechanism of secretin-induced urinary HCO3 - excretion, explain metabolic alkalosis in patients with CF, and suggest feasibility of an in vivo human CF urine test to validate drug efficacy.
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Affiliation(s)
- Peder Berg
- Department of Biomedicine, Physiology and Biophysics, Aarhus University, Aarhus, Denmark
| | - Samuel L Svendsen
- Department of Biomedicine, Physiology and Biophysics, Aarhus University, Aarhus, Denmark
| | - Mads V Sorensen
- Department of Biomedicine, Physiology and Biophysics, Aarhus University, Aarhus, Denmark
| | - Casper K Larsen
- Department of Biomedicine, Physiology and Biophysics, Aarhus University, Aarhus, Denmark
| | - Jesper Frank Andersen
- Department of Biomedicine, Physiology and Biophysics, Aarhus University, Aarhus, Denmark
| | - Søren Jensen-Fangel
- Department of Infectious Diseases, Aarhus University Hospital, Aarhus, Denmark
| | - Majbritt Jeppesen
- Department of Infectious Diseases, Aarhus University Hospital, Aarhus, Denmark
| | - Rainer Schreiber
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Ines Cabrita
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Karl Kunzelmann
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Jens Leipziger
- Department of Biomedicine, Physiology and Biophysics, Aarhus University, Aarhus, Denmark
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20
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Wall SM, Verlander JW, Romero CA. The Renal Physiology of Pendrin-Positive Intercalated Cells. Physiol Rev 2020; 100:1119-1147. [PMID: 32347156 PMCID: PMC7474261 DOI: 10.1152/physrev.00011.2019] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 11/06/2019] [Accepted: 11/12/2019] [Indexed: 12/13/2022] Open
Abstract
Intercalated cells (ICs) are found in the connecting tubule and the collecting duct. Of the three IC subtypes identified, type B intercalated cells are one of the best characterized and known to mediate Cl- absorption and HCO3- secretion, largely through the anion exchanger pendrin. This exchanger is thought to act in tandem with the Na+-dependent Cl-/HCO3- exchanger, NDCBE, to mediate net NaCl absorption. Pendrin is stimulated by angiotensin II and aldosterone administration via the angiotensin type 1a and the mineralocorticoid receptors, respectively. It is also stimulated in models of metabolic alkalosis, such as with NaHCO3 administration. In some rodent models, pendrin-mediated HCO3- secretion modulates acid-base balance. However, of probably more physiological or clinical significance is the role of these pendrin-positive ICs in blood pressure regulation, which occurs, at least in part, through pendrin-mediated renal Cl- absorption, as well as their effect on the epithelial Na+ channel, ENaC. Aldosterone stimulates ENaC directly through principal cell mineralocorticoid hormone receptor (ligand) binding and also indirectly through its effect on pendrin expression and function. In so doing, pendrin contributes to the aldosterone pressor response. Pendrin may also modulate blood pressure in part through its action in the adrenal medulla, where it modulates the release of catecholamines, or through an indirect effect on vascular contractile force. In addition to its role in Na+ and Cl- balance, pendrin affects the balance of other ions, such as K+ and I-. This review describes how aldosterone and angiotensin II-induced signaling regulate pendrin and the contribution of pendrin-positive ICs in the kidney to distal nephron function and blood pressure.
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Affiliation(s)
- Susan M Wall
- Departments of Medicine and Physiology, Emory University School of Medicine, Atlanta, Georgia; and Department of Medicine, University of Florida, Gainesville, Florida
| | - Jill W Verlander
- Departments of Medicine and Physiology, Emory University School of Medicine, Atlanta, Georgia; and Department of Medicine, University of Florida, Gainesville, Florida
| | - Cesar A Romero
- Departments of Medicine and Physiology, Emory University School of Medicine, Atlanta, Georgia; and Department of Medicine, University of Florida, Gainesville, Florida
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21
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Rehman T, Thornell IM, Pezzulo AA, Thurman AL, Romano Ibarra GS, Karp PH, Tan P, Duffey ME, Welsh MJ. TNFα and IL-17 alkalinize airway surface liquid through CFTR and pendrin. Am J Physiol Cell Physiol 2020; 319:C331-C344. [PMID: 32432926 PMCID: PMC7500220 DOI: 10.1152/ajpcell.00112.2020] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The pH of airway surface liquid (ASL) is a key factor that determines respiratory host defense; ASL acidification impairs and alkalinization enhances key defense mechanisms. Under healthy conditions, airway epithelia secrete base ([Formula: see text]) and acid (H+) to control ASL pH (pHASL). Neutrophil-predominant inflammation is a hallmark of several airway diseases, and TNFα and IL-17 are key drivers. However, how these cytokines perturb pHASL regulation is uncertain. In primary cultures of differentiated human airway epithelia, TNFα decreased and IL-17 did not change pHASL. However, the combination (TNFα+IL-17) markedly increased pHASL by increasing [Formula: see text] secretion. TNFα+IL-17 increased expression and function of two apical [Formula: see text] transporters, CFTR anion channels and pendrin Cl-/[Formula: see text] exchangers. Both were required for maximal alkalinization. TNFα+IL-17 induced pendrin expression primarily in secretory cells where it was coexpressed with CFTR. Interestingly, significant pendrin expression was not detected in CFTR-rich ionocytes. These results indicate that TNFα+IL-17 stimulate [Formula: see text] secretion via CFTR and pendrin to alkalinize ASL, which may represent an important defense mechanism in inflamed airways.
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Affiliation(s)
- Tayyab Rehman
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Ian M Thornell
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Alejandro A Pezzulo
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Andrew L Thurman
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Guillermo S Romano Ibarra
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Philip H Karp
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa.,Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Ping Tan
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Michael E Duffey
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York
| | - Michael J Welsh
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa.,Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa.,Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
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22
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Saracyn M, Lubas A, Bober B, Kowalski Ł, Kapusta W, Niemczyk S, Wartofsky L, Kamiński G. Recombinant Human Thyrotropin Worsens Renal Cortical Perfusion and Renal Function in Patients After Total Thyroidectomy Due to Differentiated Thyroid Cancer. Thyroid 2020; 30:653-660. [PMID: 31964314 DOI: 10.1089/thy.2019.0372] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Background: Although thyrotropin (TSH) receptors are found in many nonthyroid tissues, we know little about the direct action of TSH on these receptors. Patients after total thyroidectomy for differentiated thyroid cancer (DTC) provide an interesting model for studying this issue. The administration of exogenous TSH in patients with an established thyroid state on levothyroxine (LT4) treatment allows us to study the effect of elevated TSH concentrations independent of thyroid status on the function of various organs, including the kidneys. The aim of this study was to assess the effects of the administration of recombinant human TSH (rhTSH) on renal perfusion and glomerular filtration in this group of patients. Methods: The study included 24 patients after total thyroidectomy due to DTC, without concomitant diseases, receiving only LT4 who qualified for radioiodine treatment (RIT). For two consecutive days, the patients received rhTSH and subsequently the RIT. Clinical and biochemical evaluation of thyroid and renal function was carried out before and 24 hours after the second dose of rhTSH and before the RIT. On the sixth day of hospitalization, the patients' glomerular filtration rate was re-evaluated. Kidney perfusion was assessed using color Doppler ultrasound imaging before and 24 hours after the second dose of rhTSH and before the RIT. Results: The administration of rhTSH to patients after total thyroidectomy due to DTC caused significant deterioration of renal perfusion after the second dose of rhTSH before the RIT, which was followed by a significant reduction in glomerular filtration. Furthermore, rhTSH did not significantly affect the hemodynamic parameters that could worsen renal function. Conclusions: This study indicates that TSH alone, independent of thyroid hormone concentrations, can influence renal perfusion and renal function.
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Affiliation(s)
- Marek Saracyn
- Department of Endocrinology and Radioisotope Therapy, Nephrology and Dialysotherapy, Military Medical Institute, Warsaw, Poland
| | - Arkadiusz Lubas
- Department of Internal Diseases, Nephrology and Dialysotherapy, Military Medical Institute, Warsaw, Poland
| | - Barbara Bober
- Department of Endocrinology and Radioisotope Therapy, Nephrology and Dialysotherapy, Military Medical Institute, Warsaw, Poland
| | - Łukasz Kowalski
- Department of Endocrinology and Radioisotope Therapy, Nephrology and Dialysotherapy, Military Medical Institute, Warsaw, Poland
| | - Waldemar Kapusta
- Department of Endocrinology and Radioisotope Therapy, Nephrology and Dialysotherapy, Military Medical Institute, Warsaw, Poland
| | - Stanisław Niemczyk
- Department of Internal Diseases, Nephrology and Dialysotherapy, Military Medical Institute, Warsaw, Poland
| | - Leonard Wartofsky
- Georgetown University School of Medicine, Washington, District of Columbia, USA
- Thyroid Cancer Research Unit, MedStar Health Research Institute, Washington, District of Columbia, USA
| | - Grzegorz Kamiński
- Department of Endocrinology and Radioisotope Therapy, Nephrology and Dialysotherapy, Military Medical Institute, Warsaw, Poland
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23
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Kim D, Huang J, Billet A, Abu-Arish A, Goepp J, Matthes E, Tewfik MA, Frenkiel S, Hanrahan JW. Pendrin Mediates Bicarbonate Secretion and Enhances Cystic Fibrosis Transmembrane Conductance Regulator Function in Airway Surface Epithelia. Am J Respir Cell Mol Biol 2020; 60:705-716. [PMID: 30742493 DOI: 10.1165/rcmb.2018-0158oc] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Bicarbonate facilitates mucin unpacking and bacterial killing; however, its transport mechanisms in the airways are not well understood. cAMP stimulates anion efflux through the cystic fibrosis (CF) transmembrane conductance regulator (CFTR; ABCC7) anion channel, and this is defective in CF. The anion exchanger pendrin (SLC26A4) also mediates HCO3- efflux and is upregulated by proinflammatory cytokines. Here, we examined pendrin and CFTR expression and their contributions to HCO3- secretion by human nasal and bronchial epithelia. In native tissue, both proteins were most abundant at the apical pole of ciliated surface cells with little expression in submucosal glands. In well-differentiated primary nasal and bronchial cell cultures, IL-4 dramatically increased pendrin mRNA levels and apical immunostaining. Exposure to low-Cl- apical solution caused intracellular alkalinization (ΔpHi) that was enhanced fourfold by IL-4 pretreatment. ΔpHi was unaffected by 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) or CFTR inhibitor CFTRinh-172, but was reduced by adenoviral shRNA targeting pendrin. Forskolin increased ΔpHi, and this stimulation was prevented by CFTRinh-172, implicating CFTR, yet forskolin only increased ΔpHi after pendrin expression had been induced by IL-4. The dependence of ΔpHi on pendrin suggests there is minimal electrical coupling between Cl- and HCO3- fluxes and that CFTR activation increases anion exchange-mediated HCO3- influx. Conversely, inducing pendrin expression increased forskolin-stimulated, CFTRinh-172-sensitive current by approximately twofold in epithelial and nonepithelial cells. We conclude that pendrin mediates most HCO3- secretion across airway surface epithelium during inflammation and enhances electrogenic Cl- secretion via CFTR, as described for other SLC26A transporters.
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Affiliation(s)
- Dusik Kim
- 1 Department of Physiology and.,2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and
| | - Junwei Huang
- 1 Department of Physiology and.,2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and
| | - Arnaud Billet
- 1 Department of Physiology and.,2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and
| | - Asmahan Abu-Arish
- 1 Department of Physiology and.,2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and
| | - Julie Goepp
- 1 Department of Physiology and.,2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and
| | - Elizabeth Matthes
- 1 Department of Physiology and.,2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and
| | - Marc A Tewfik
- 2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and.,3 Department of Otolaryngology-Head and Neck Surgery and
| | - Saul Frenkiel
- 2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and.,3 Department of Otolaryngology-Head and Neck Surgery and
| | - John W Hanrahan
- 1 Department of Physiology and.,2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and.,4 Research Institute, McGill University Health Centre, Montréal, Québec, Canada
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24
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Wasano K, Takahashi S, Rosenberg SK, Kojima T, Mutai H, Matsunaga T, Ogawa K, Homma K. Systematic quantification of the anion transport function of pendrin (SLC26A4) and its disease-associated variants. Hum Mutat 2020; 41:316-331. [PMID: 31599023 PMCID: PMC6930342 DOI: 10.1002/humu.23930] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 10/01/2019] [Accepted: 10/03/2019] [Indexed: 01/14/2023]
Abstract
Thanks to the advent of rapid DNA sequencing technology and its prevalence, many disease-associated genetic variants are rapidly identified in many genes from patient samples. However, the subsequent effort to experimentally validate and define their pathological roles is extremely slow. Consequently, the pathogenicity of most disease-associated genetic variants is solely speculated in silico, which is no longer deemed compelling. We developed an experimental approach to efficiently quantify the pathogenic effects of disease-associated genetic variants with a focus on SLC26A4, which is essential for normal inner ear function. Alterations of this gene are associated with both syndromic and nonsyndromic hereditary hearing loss with various degrees of severity. We established HEK293T-based stable cell lines that express pendrin missense variants in a doxycycline-dependent manner, and systematically determined their anion transport activities with high accuracy in a 96-well plate format using a high throughput plate reader. Our doxycycline dosage-dependent transport assay objectively distinguishes missense variants that indeed impair the function of pendrin from those that do not (functional variants). We also found that some of these putative missense variants disrupt normal messenger RNA splicing. Our comprehensive experimental approach helps determine the pathogenicity of each pendrin variant, which should guide future efforts to benefit patients.
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Affiliation(s)
- Koichiro Wasano
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Laboratory of Auditory Disorders, Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo 152-8902, Japan
| | - Satoe Takahashi
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Samuel K. Rosenberg
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Takashi Kojima
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Hideki Mutai
- Laboratory of Auditory Disorders, Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo 152-8902, Japan
| | - Tatsuo Matsunaga
- Laboratory of Auditory Disorders, Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo 152-8902, Japan
| | - Kaoru Ogawa
- Department of Otolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo 160-8582, Japan
| | - Kazuaki Homma
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, IL 60608, USA
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25
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Kim MA, Kim SH, Ryu N, Ma JH, Kim YR, Jung J, Hsu CJ, Choi JY, Lee KY, Wangemann P, Bok J, Kim UK. Gene therapy for hereditary hearing loss by SLC26A4 mutations in mice reveals distinct functional roles of pendrin in normal hearing. Theranostics 2019; 9:7184-7199. [PMID: 31695761 PMCID: PMC6831294 DOI: 10.7150/thno.38032] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 08/06/2019] [Indexed: 12/13/2022] Open
Abstract
Rationale: Mutations of SLC26A4 that abrogate pendrin, expressed in endolymphatic sac, cochlea and vestibule, are known to cause autosomal recessive sensorineural hearing loss with enlargement of the membranous labyrinth. This is the first study to demonstrate the feasibility of gene therapy for pendrin-related hearing loss. Methods: We used a recombinant viral vector to transfect Slc26a4 cDNA into embryonic day 12.5 otocysts of pendrin-deficient knock-out (Slc26a4∆/∆ ) and pendrin-deficient knock-in (Slc26a4tm1Dontuh/tm1Dontuh ) mice. Results: Local gene-delivery resulted in spatially and temporally limited pendrin expression, prevented enlargement, failed to restore vestibular function, but succeeded in the restoration of hearing. Restored hearing phenotypes included normal hearing as well as sudden, fluctuating, and progressive hearing loss. Conclusion: Our study illustrates the feasibility of gene therapy for pendrin-related hearing loss, suggests differences in the requirement of pendrin between the cochlea and the vestibular labyrinth, and documents that insufficient pendrin expression during late embryonal and early postnatal development of the inner ear can cause sudden, fluctuating and progressive hearing loss without obligatory enlargement of the membranous labyrinth.
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Affiliation(s)
- Min-A Kim
- Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu 41566, Republic of Korea
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Sung Huhn Kim
- Department of Otorhinolaryngology, Head and Neck Surgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Nari Ryu
- Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu 41566, Republic of Korea
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Ji-Hyun Ma
- Department of Anatomy, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Ye-Ri Kim
- Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu 41566, Republic of Korea
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Jinsei Jung
- Department of Otorhinolaryngology, Head and Neck Surgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Chuan-Jen Hsu
- Department of Otolaryngology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jae Young Choi
- Department of Otorhinolaryngology, Head and Neck Surgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Kyu-Yup Lee
- Department of Otorhinolaryngology-Head and Neck Surgery, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea
| | - Philine Wangemann
- Department of Anatomy and Physiology, Kansas State University, Manhattan, United States of America
| | - Jinwoong Bok
- Department of Otorhinolaryngology, Head and Neck Surgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
- Department of Anatomy, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
- BK21PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Un-Kyung Kim
- Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu 41566, Republic of Korea
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, Republic of Korea
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26
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Zhu JS, Lu JY, Tan JA, Rivera AA, Phuan PW, Shatskikh ME, Son JH, Haggie PM, Verkman AS, Kurth MJ. Synthesis and evaluation of tetrahydropyrazolopyridine inhibitors of anion exchange protein SLC26A4 (pendrin). Bioorg Med Chem Lett 2019; 29:2119-2123. [PMID: 31281021 DOI: 10.1016/j.bmcl.2019.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/29/2019] [Accepted: 07/01/2019] [Indexed: 01/03/2023]
Abstract
Pendrin is a transmembrane chloride/anion antiporter that is strongly upregulated in the airways in rhinoviral infection, asthma, cystic fibrosis and chronic rhinosinusitis. Based on its role in the regulation of airway surface liquid depth, pendrin inhibitors have potential indications for treatment of inflammatory airways diseases. Here, a completely regioselective route to tetrahydro-pyrazolopyridine pendrin inhibitors based on 1,3-diketone and substituted hydrazine condensation was been developed. Structure-activity relationships at the tetrahydropyridyl nitrogen were investigated using a focused library, establishing the privileged nature of N-phenyl ureas and improving inhibitor potency by greater than 2-fold.
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Affiliation(s)
- Jie S Zhu
- Department of Chemistry, University of California, Davis, CA 95616, United States
| | - Julia Y Lu
- Department of Chemistry, University of California, Davis, CA 95616, United States
| | - Joseph-Anthony Tan
- Departments of Medicine & Physiology, University of California, San Francisco, CA 94143, United States
| | - Amber A Rivera
- Departments of Medicine & Physiology, University of California, San Francisco, CA 94143, United States
| | - Puay-Wah Phuan
- Departments of Medicine & Physiology, University of California, San Francisco, CA 94143, United States
| | - Marina E Shatskikh
- Department of Chemistry, University of California, Davis, CA 95616, United States
| | - Jung-Ho Son
- Department of Chemistry, University of California, Davis, CA 95616, United States
| | - Peter M Haggie
- Departments of Medicine & Physiology, University of California, San Francisco, CA 94143, United States
| | - Alan S Verkman
- Departments of Medicine & Physiology, University of California, San Francisco, CA 94143, United States
| | - Mark J Kurth
- Department of Chemistry, University of California, Davis, CA 95616, United States.
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27
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Fehsenfeld S, Kolosov D, Wood CM, O'Donnell MJ. Section-specific H + flux in renal tubules of fasted and fed goldfish. ACTA ACUST UNITED AC 2019; 222:jeb.200964. [PMID: 31138633 DOI: 10.1242/jeb.200964] [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: 01/31/2019] [Accepted: 05/21/2019] [Indexed: 12/12/2022]
Abstract
A recent study demonstrated that in response to a feeding-induced metabolic acidosis, goldfish (Carassius auratus) adjust epithelial protein and/or mRNA expression in their kidney tubules for multiple transporters known to be relevant for acid-base regulation. These include Na+/H+ exchanger (NHE), V-type H+-ATPase (V-ATPase), cytoplasmic carbonic anhydrase, HCO3 - transporters and Rhesus proteins. Consequently, renal acid output in the form of protons and NH4 + increases. However, little is known about the mechanistic details of renal acid-base regulation in C. auratus and teleost fishes in general. The present study applied the scanning ion-selective electrode technique (SIET) to measure proton flux in proximal, distal and connecting tubules of goldfish. We detected increased H+ efflux into the extracellular fluid from the tubule in fed animals, resulting from paracellular back-flux of H+ through the tight junction. By applying inhibitors for selected acid-base regulatory epithelial transporters, we found that cytosolic carbonic anhydrase and HCO3 - transporters were important in mediating H+ flux in all three tubule segments of fed goldfish. Contrastingly, V-ATPase seemed to play a role in H+ flux only in proximal and distal tubules, and NHE in proximal and connecting tubules. We developed working models for transport of acid-base relevant equivalents (H+, HCO3 -, NH3/NH4 +) for each tubule segment in C. auratus kidney. While the proximal tubule appears to play a major role in both H+ secretion and HCO3 - reabsorption, the distal and connecting tubules seem to mainly serve for HCO3 - reabsorption and NH3/NH4 + secretion.
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Affiliation(s)
- Sandra Fehsenfeld
- Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, Rimouski, QC, G5L 3A1, Canada .,Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Dennis Kolosov
- Department of Biology, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | - Chris M Wood
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.,Department of Biology, McMaster University, Hamilton, ON, L8S 4K1, Canada
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28
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Pourahmadiyan A, Alipour P, Fattahi N, Kasiri M, Rezaeian F, Taghipour-Sheshdeh A, Mohammadi-Asl J, Tabatabaiefar MA, Hashemzadeh Chaleshtori M. A pathogenic variant in SLC26A4 is associated with Pendred syndrome in a consanguineous Iranian family. Int J Audiol 2019; 58:628-634. [PMID: 31187663 DOI: 10.1080/14992027.2019.1619945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Objective: Hearing loss (HL) is a common sensory deficit with high phenotypic and genotypic heterogeneity. A large Iranian family with HL was genetically assessed in this study. Design: A proband from a consanguineous multiplex HL family from Iran was examined via Targeted Next-Generation Sequencing (TNGS). Sanger sequencing allowed the segregation analysis of the variant of interest and the investigation of its presence in a cohort of 50 ethnicity-matched healthy control individuals. The gene was previously associated with HL. Therefore, to determine whether the variant was specifically associated with Pendred Syndrome (PDS) or DFNB4, biochemical analyses, PTA, thyroid scans by Tc99m, perchlorate discharge test and high-resolution CT scan of the temporal bone were carried out on the affected family members. Study sample: Ten members of a large multiplex Iranian family with HL were recruited in this study. In addition, 50 unrelated healthy controls of the same ethnic group were randomly selected to genotype the variant. Results: A homozygous missense variant (NM_000441.1: c.1211C > T/p.Thr404Ile) in exon 10 was found segregating in the family. Based on the ACMG's guidelines, the variant was classified as pathogenic. Conclusion: This study expands the spectrum of SLC26A4 pathogenic variants in hearing loss.
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Affiliation(s)
- Azam Pourahmadiyan
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences , Shahrekord , Iran
| | - Paria Alipour
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences , Shahrekord , Iran
| | - Najmeh Fattahi
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences , Shahrekord , Iran
| | - Mahbubeh Kasiri
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences , Shahrekord , Iran
| | - Fateme Rezaeian
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences , Shahrekord , Iran
| | - Afsaneh Taghipour-Sheshdeh
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences , Shahrekord , Iran
| | - Javad Mohammadi-Asl
- Department of Medical Genetics, School of Medicine, Ahvaz Jundishapur University of Medical Sciences , Ahvaz , Iran
| | - Mohammad Amin Tabatabaiefar
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences , Isfahan , Iran.,Pediatric Inherited Diseases Research Center, Research Institute for Primordial Prevention of Non-communicable Disease, Isfahan University of Medical Sciences , Isfahan , Iran
| | - Morteza Hashemzadeh Chaleshtori
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences , Shahrekord , Iran
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29
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Lashhab R, Ullah AS, Cordat E. Renal collecting duct physiology and pathophysiology. Biochem Cell Biol 2019; 97:234-242. [DOI: 10.1139/bcb-2018-0192] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Rawad Lashhab
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - A.K.M. Shahid Ullah
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Emmanuelle Cordat
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
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30
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Wen Z, Zhu H, Li Z, Zhang S, Zhang A, Zhang T, Fu X, Sun D, Zhang J, Gao J. A knock-in mouse model of Pendred syndrome with Slc26a4 L236P mutation. Biochem Biophys Res Commun 2019; 515:359-365. [PMID: 31155292 DOI: 10.1016/j.bbrc.2019.05.157] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 05/25/2019] [Indexed: 11/25/2022]
Abstract
SLC26A4 gene mutations lead to Pendred syndrome and non-syndromic hearing loss (DFNB4). The mouse model is well used to study the pathology of Pendred syndrome, however, mice with different Slc26a4 mutations exhibit different phenotypes, and these mice have severe deafness and inner ear malformations that are not imitated less severely Human phenotype. In this study, we generated a knock-in mouse model of Pendred syndrome with Slc26a4 L236P mutation to mimic the most common mutation found in human. Some L236P mice were observed to have significant vestibular dysfunction including torticollis and circling, the giant otoconia and destruction of the otoconial membrane was observed in L236P mice. Unlike other profoundly deafness in Slc26a4 mouse model, L236P mice present mild to profound hearing loss, consistent with the hearing threshold, inner ear hair cells also lost from slight to significant. Together, these data demonstrate that the L236P mouse phenotype is more similar to the human phenotype and should be used as a tool for further research into the human Pendred syndrome.
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Affiliation(s)
- Zongzhuang Wen
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, Shandong, China
| | - Haixia Zhu
- State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, China
| | - Zhenzu Li
- Department of Bioengineering, Shandong Polytechnic, Jinan, Shandong, China
| | - Sen Zhang
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, Shandong, China
| | - Aizhen Zhang
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, Shandong, China
| | - Tingting Zhang
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, Shandong, China
| | - Xiaolong Fu
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, Shandong, China
| | - Daqing Sun
- Department of Paediatric Surgery, Tianjin Medical University General Hospital, Tianjin, China.
| | - Jian Zhang
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, Shandong, China.
| | - Jiangang Gao
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan, Shandong, China.
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31
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Electrolyte transport in the renal collecting duct and its regulation by the renin-angiotensin-aldosterone system. Clin Sci (Lond) 2019; 133:75-82. [PMID: 30622159 DOI: 10.1042/cs20180194] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 11/29/2018] [Accepted: 12/17/2018] [Indexed: 01/13/2023]
Abstract
Distal nephron of the kidney plays key roles in fluid volume and electrolyte homeostasis by tightly regulating reabsorption and excretion of Na+, K+, and Cl- Studies to date demonstrate the detailed electrolyte transport mechanisms in principal cells of the cortical collecting duct, and their regulation by renin-angiotensin-aldosterone system (RAAS). In recent years, however, accumulating data indicate that intercalated cells, another cell type that is present in the cortical collecting duct, also play active roles in the regulation of blood pressure. Notably, pendrin in β-intercalated cells not only controls acid/base homeostasis, but is also one of the key components controlling salt and K+ transport in distal nephron. We have recently shown that pendrin is regulated by the co-ordinated action of angiotensin II (AngII) and aldosterone, and at the downstream of AngII, mammalian target of rapamycin (mTOR) signaling regulates pendrin through inhibiting the kinase unc51-like-kinase 1 and promoting dephosphorylation of mineralocorticoid receptor (MR). In this review, we summarize recent advances in the current knowledge on the salt transport mechanisms in the cortical collecting duct, and their regulation by the RAAS.
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32
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Yang T, Guo L, Wang L, Yu X. Diagnosis, Intervention, and Prevention of Genetic Hearing Loss. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1130:73-92. [PMID: 30915702 DOI: 10.1007/978-981-13-6123-4_5] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
It is estimated that at least 50% of congenital or childhood hearing loss is attributable to genetic causes. In non-syndromic hearing loss, which accounts for 70% of genetic hearing loss, approximately 80% of cases are autosomal recessive, 15% autosomal dominant, and 1-2% mitochondrial or X-linked. In addition, 30% of genetic hearing loss is syndromic. The genetic causes of hearing loss are highly heterogeneous. So far, more than 140 deafness-related genes have been discovered. Studies on those genes tremendously increased our understanding of the inner ear functions at the molecular level. It also offers important information for the patients and allows personalized and accurate genetic counseling. In many cases, genetic diagnosis of hearing loss can help to avoid unnecessary and costly clinical testing, offer prognostic information, and guide future medical management. On the other hand, a variety of gene therapeutic approaches have been developed aiming to relieve or converse the hearing loss due to genetic causes. Prevention of genetic hearing loss is feasible through prepregnancy and prenatal genetic diagnosis and counseling.
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Affiliation(s)
- Tao Yang
- Department of Otorhinolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China. .,Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, China. .,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
| | - Luo Guo
- Key Laboratory of Hearing Medicine of NHFPC, ENT Institute and Otorhinolaryngology Department, Shanghai Engineering Research Centre of Cochlear Implant, Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
| | - Longhao Wang
- Department of Otorhinolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.,Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, China.,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Xiaoyu Yu
- Department of Otorhinolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.,Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, China.,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
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33
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Teulon J, Planelles G, Sepúlveda FV, Andrini O, Lourdel S, Paulais M. Renal Chloride Channels in Relation to Sodium Chloride Transport. Compr Physiol 2018; 9:301-342. [DOI: 10.1002/cphy.c180024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Barone S, Xu J, Zahedi K, Brooks M, Soleimani M. Probenecid Pre-treatment Downregulates the Kidney Cl -/HCO 3- Exchanger (Pendrin) and Potentiates Hydrochlorothiazide-Induced Diuresis. Front Physiol 2018; 9:849. [PMID: 30050451 PMCID: PMC6050369 DOI: 10.3389/fphys.2018.00849] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 06/14/2018] [Indexed: 01/14/2023] Open
Abstract
Background: Probenecid is a uricosuric agent that in addition to exerting a positive ionotropic effect in the heart, blocks the ATP transporter Pannexin 1 and inhibits the Cl-/HCO3- exchanger, pendrin. In the kidney, pendrin blunts the loss of salt wasting secondary to the inhibition of the thiazide-sensitive Na+-Cl- co-transporter (NCC/SLC12A3). Hypothesis: Pre-treatment with probenecid down-regulates pendrin; therefore, leaving NCC as the main salt absorbing transporter in the distal nephron, and hence enhances the hydrochlorothiazide (HCTZ)-induced diuresis. Methods: Daily balance studies, blood and urine chemical analysis, immunofluorescence, as well as western and northern blot analyses were utilized to examine the effects of probenecid alone (at 250 mg/kg/day) or in combination with HCTZ (at 40 mg/kg/day) on kidney function and on salt and water transporters in the collecting duct. Results: Male Sprague Dawley rats were subjected to three different protocols: (1) HCTZ for 4 days, (2) probenecid for 10 days, and (3) primed with probenecid for 6 days followed by probenecid and HCTZ for 4 additional days. Treatment protocol 1 (HCTZ for 4 days) only mildly increased the urine volume (U Vol) from a baseline of 9.8-13.4 ml/day. In response to treatment protocol 2 (probenecid for 10 days), U Vol increased to 15.9 ml/24 h. Treatment protocol 3 (probenecid for 6 days followed by probenecid and HCTZ for 4 additional days) increased the U Vol to 42.9 ml/day on day 4 of co-treatment with HCTZ and probenecid (compared to probenecid p = 0.003, n = 5 or HCTZ alone p = 0.001, n = 5). Probenecid treatment at 250 mg/kg/day downregulated the expression of pendrin and led to a decrease in AQP2 expression. Enhanced diuresis by probenecid plus HCTZ was not associated with volume depletion. Conclusion: Probenecid pre-treatment downregulates pendrin and robustly enhances diuresis by HCTZ-mediated NCC inhibition in kidney.
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Affiliation(s)
- Sharon Barone
- Department of Medicine, University of Cincinnati, Cincinnati, OH, United States
- Research Services, VA Medical Center, Cincinnati, OH, United States
| | - Jie Xu
- Department of Medicine, University of Cincinnati, Cincinnati, OH, United States
- Center on Genetics of Transport and Epithelial Biology, University of Cincinnati, Cincinnati, OH, United States
| | - Kamyar Zahedi
- Department of Medicine, University of Cincinnati, Cincinnati, OH, United States
- Research Services, VA Medical Center, Cincinnati, OH, United States
| | - Marybeth Brooks
- Department of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Manoocher Soleimani
- Department of Medicine, University of Cincinnati, Cincinnati, OH, United States
- Research Services, VA Medical Center, Cincinnati, OH, United States
- Center on Genetics of Transport and Epithelial Biology, University of Cincinnati, Cincinnati, OH, United States
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Wall SM. Renal intercalated cells and blood pressure regulation. Kidney Res Clin Pract 2017; 36:305-317. [PMID: 29285423 PMCID: PMC5743040 DOI: 10.23876/j.krcp.2017.36.4.305] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 11/17/2017] [Accepted: 11/20/2017] [Indexed: 12/12/2022] Open
Abstract
Type B and non-A, non-B intercalated cells are found within the connecting tubule and the cortical collecting duct. Of these cell types, type B intercalated cells are known to mediate Cl- absorption and HCO3- secretion largely through pendrin-dependent Cl-/HCO3- exchange. This exchange is stimulated by angiotensin II administration and is also stimulated in models of metabolic alkalosis, for instance after aldosterone or NaHCO3 administration. In some rodent models, pendrin-mediated HCO3- secretion modulates acid-base balance. However, the role of pendrin in blood pressure regulation is likely of more physiological or clinical significance. Pendrin regulates blood pressure not only by mediating aldosterone-sensitive Cl- absorption, but also by modulating the aldosterone response for epithelial Na+ channel (ENaC)-mediated Na+ absorption. Pendrin regulates ENaC through changes in open channel of probability, channel surface density, and channels subunit total protein abundance. Thus, aldosterone stimulates ENaC activity through both direct and indirect effects, the latter occurring through its stimulation of pendrin expression and function. Therefore, pendrin contributes to the aldosterone pressor response. Pendrin may also modulate blood pressure in part through its action in the adrenal medulla, where it modulates the release of catecholamines, or through an indirect effect on vascular contractile force. This review describes how aldosterone and angiotensin II-induced signaling regulate pendrin and the contributory role of pendrin in distal nephron function and blood pressure.
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Affiliation(s)
- Susan M. Wall
- Departments of Medicine, Emory University School of Medicine, Atlanta, GA,
USA
- Physiology, Emory University School of Medicine, Atlanta, GA,
USA
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CK2 is a key regulator of SLC4A2-mediated Cl -/HCO 3- exchange in human airway epithelia. Pflugers Arch 2017; 469:1073-1091. [PMID: 28455748 PMCID: PMC5554290 DOI: 10.1007/s00424-017-1981-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 03/27/2017] [Accepted: 04/10/2017] [Indexed: 12/17/2022]
Abstract
Transepithelial bicarbonate secretion by human airway submucosal glands and surface epithelial cells is crucial to maintain the pH-sensitive innate defence mechanisms of the lung. cAMP agonists stimulate HCO3- secretion via coordinated increases in basolateral HCO3- influx and accumulation, as well as CFTR-dependent HCO3- efflux at the luminal membrane of airway epithelial cells. Here, we investigated the regulation of a basolateral located, DIDS-sensitive, Cl-/HCO3- exchanger, anion exchanger 2 (AE2; SLC4A2) which is postulated to act as an acid loader, and therefore potential regulator of HCO3- secretion, in human airway epithelial cells. Using intracellular pH measurements performed on Calu-3 cells, we demonstrate that the activity of the basolateral Cl-/HCO3- exchanger was significantly downregulated by cAMP agonists, via a PKA-independent mechanism and also required Ca2+ and calmodulin under resting conditions. AE2 contains potential phosphorylation sites by a calmodulin substrate, protein kinase CK2, and we demonstrated that AE2 activity was reduced in the presence of CK2 inhibition. Moreover, CK2 inhibition abolished the activity of AE2 in primary human nasal epithelia. Studies performed on mouse AE2 transfected into HEK-293T cells confirmed almost identical Ca2+/calmodulin and CK2 regulation to that observed in Calu-3 and primary human nasal cells. Furthermore, mouse AE2 activity was reduced by genetic knockout of CK2, an effect which was rescued by exogenous CK2 expression. Together, these findings are the first to demonstrate that CK2 is a key regulator of Cl--dependent HCO3- export at the serosal membrane of human airway epithelial cells.
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Russo A, Ranieri M, Di Mise A, Dossena S, Pellegrino T, Furia E, Nofziger C, Debellis L, Paulmichl M, Valenti G, Tamma G. Interleukin-13 increases pendrin abundance to the cell surface in bronchial NCI-H292 cells via Rho/actin signaling. Pflugers Arch 2017; 469:1163-1176. [PMID: 28378089 DOI: 10.1007/s00424-017-1970-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 03/20/2017] [Accepted: 03/22/2017] [Indexed: 11/28/2022]
Abstract
Interleukin-13 (IL13) is a major player in the development of airway hyperresponsiveness in several respiratory disorders. Emerging data suggest that an increased expression of pendrin in airway epithelia is associated with elevated airway hyperreactivity in asthma. Here, we investigate the effect of IL13 on pendrin localization and function using bronchiolar NCI-H292 cells. The data obtained revealed that IL13 increases the cell surface expression of pendrin. This effect was paralleled by a significant increase in the intracellular pH, possibly via indirect stimulation of NHE. IL13 effect on pendrin localization and intracellular pH was reversed by theophylline, a bronchodilator compound used to treat asthma. IL13 upregulated RhoA activity, a crucial protein controlling actin dynamics, via G-alpha-13. Specifically, IL13 stabilized actin cytoskeleton and promoted co-localization and a direct molecular interaction between pendrin and F-actin in the plasma membrane region. These effects were reversed following exposure of cells to theophylline. Selective inhibition of Rho kinase, a downstream effector of Rho, reduced the IL13-dependent cell surface expression of pendrin. Together, these data indicate that IL13 increases pendrin abundance to the cell surface via Rho/actin signaling, an effect reversed by theophylline.
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Affiliation(s)
- Annamaria Russo
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125, Bari, Italy
| | - Marianna Ranieri
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125, Bari, Italy.
| | - Annarita Di Mise
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125, Bari, Italy
| | - Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Tommaso Pellegrino
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125, Bari, Italy
| | - Emilia Furia
- Department of Chemistry and Chemical Technologies, University of Calabria, Rende, Italy
| | - Charity Nofziger
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Lucantonio Debellis
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125, Bari, Italy
| | - Markus Paulmichl
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Giovanna Valenti
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125, Bari, Italy.,Istituto Nazionsale di Biostrutture e Biosistemi (I.N.B.B.), Rome, Italy.,Centre of Excellence Genomic and Proteomics GEBCA, University of Bari, Bari, Italy
| | - Grazia Tamma
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125, Bari, Italy. .,Istituto Nazionsale di Biostrutture e Biosistemi (I.N.B.B.), Rome, Italy.
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Abstract
Pendred syndrome is an autosomal recessive disorder that is classically defined by the combination of sensorineural deafness/hearing impairment, goiter, and an abnormal organification of iodide with or without hypothyroidism. The hallmark of the syndrome is the impaired hearing, which is associated with inner ear malformations such as an enlarged vestibular aqueduct (EVA). The thyroid phenotype is variable and may be modified by the nutritional iodine intake. Pendred syndrome is caused by biallelic mutations in the SLC26A4/PDS gene, which encodes the multifunctional anion exchanger pendrin. Pendrin has affinity for chloride, iodide, and bicarbonate, among other anions. In the inner ear, pendrin functions as a chloride/bicarbonate exchanger that is essential for maintaining the composition and the potential of the endolymph. In the thyroid, pendrin is expressed at the apical membrane of thyroid cells facing the follicular lumen. Functional studies have demonstrated that pendrin can mediate iodide efflux in heterologous cells. This, together with the thyroid phenotype observed in humans (goiter, impaired iodine organification) suggests that pendrin could be involved in iodide efflux into the lumen, one of the steps required for thyroid hormone synthesis. Iodide efflux can, however, also occur in the absence of pendrin suggesting that other exchangers or channels are involved. It has been suggested that Anoctamin 1 (ANO1/TMEM16A), a calcium-activated anion channel, which is also expressed at the apical membrane of thyrocytes, could participate in mediating apical efflux. In the kidney, pendrin is involved in bicarbonate secretion and chloride reabsorption. While there is no renal phenotype under basal conditions, severe metabolic alkalosis has been reported in Pendred syndrome patients exposed to an increased alkali load. This review provides an overview on the clinical spectrum of Pendred syndrome, the functional data on pendrin with a focus on its potential role in the thyroid, as well as the controversy surrounding the relative physiological roles of pendrin and anoctamin.
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Affiliation(s)
- Jean-Louis Wémeau
- Université de Lille 2, Centre Hospitalier Régional Universitaire de Lille, Clinique Endocrinologique Marc-Linquette, 59037 Lille, France.
| | - Peter Kopp
- Northwestern University, Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Tarry 15, 303 East Chicago Avenue, Chicago, IL 60611, USA.
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Karatas A, Erdem H, Karatas Z, Ozlu T, Cakmak B. The effect of smoking on placental pendrin expression. J OBSTET GYNAECOL 2016; 37:11-14. [PMID: 28013561 DOI: 10.1080/01443615.2016.1174825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Pendrin is important for transport of iodine across the placenta. Thiocyanate coming from cigarette is a competitive inhibitor of iodine transport. We aimed to evaluate the pendrin immunostaining intensity in placentas of smoker and non-smoker women. Placental tissues from 61 women, of which 28 were in smoking, and 33 were in non-smoking group were evaluated by immunohistochemical staining. Positive immunostaining was evaluated using a semiquantitative score: 0, negative; +, mild; ++, moderate; and +++, intense. Birth weight was significantly lower in the smoker group (p = 0.024). There was a negative correlation between birth weight and intensity of placental pendrin immunostaining in the smoker group (r = -0.44, p = 0.02). Placentas of the smoking women showed significantly higher immunostaining with pendrin than the control group (p = 0.006). Thiocyonate coming from cigarettes may competitively inhibit pendrin mediated iodine transport in the placenta and adversely affect foetal development by this mechanism.
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Affiliation(s)
- Ahmet Karatas
- a Department of Obstetrics and Gynaecology , School of Medicine, Abant Izzet Baysal University, Golkoy Kampusu, Golkoy Yerleskesi , Bolu , Turkey
| | - Havva Erdem
- b Department of Medical Pathology , School of Medicine, Duzce University, Merkez Yerleskesi , Konuralp , Duzce , Turkey
| | - Zehra Karatas
- c Department of Paediatrics , School of Medicine, Abant Izzet Baysal University, Golkoy Kampusu, Golkoy Yerleskesi , Bolu , Turkey
| | - Tulay Ozlu
- a Department of Obstetrics and Gynaecology , School of Medicine, Abant Izzet Baysal University, Golkoy Kampusu, Golkoy Yerleskesi , Bolu , Turkey
| | - Bulent Cakmak
- d Department of Obstetrics and Gynaecology , School of Medicine, Gaziosmanpasa University, Sevki Erek Yerleskesi , Tokat , Turkey
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Mapping pathogenic mutations suggests an innovative structural model for the pendrin (SLC26A4) transmembrane domain. Biochimie 2016; 132:109-120. [PMID: 27771369 DOI: 10.1016/j.biochi.2016.10.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 10/03/2016] [Indexed: 12/16/2022]
Abstract
Human pendrin (SLC26A4) is an anion transporter mostly expressed in the inner ear, thyroid and kidney. SLC26A4 gene mutations are associated with a broad phenotypic spectrum, including Pendred Syndrome and non-syndromic hearing loss with enlarged vestibular aqueduct (ns-EVA). No experimental structure of pendrin is currently available, making phenotype-genotype correlations difficult as predictions of transmembrane (TM) segments vary in number. Here, we propose a novel three-dimensional (3D) pendrin transmembrane domain model based on the SLC26Dg transporter. The resulting 14 TM topology was found to include two non-canonical transmembrane segments crucial for pendrin activity. Mutation mapping of 147 clinically validated pathological mutations shows that most affect two previously undescribed TM regions.
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Kim BG, Yoo TH, Yoo JE, Seo YJ, Jung J, Choi JY. Resistance to hypertension and high Cl - excretion in humans with SLC26A4 mutations. Clin Genet 2016; 91:448-452. [PMID: 27090054 DOI: 10.1111/cge.12789] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 04/12/2016] [Accepted: 04/14/2016] [Indexed: 10/21/2022]
Abstract
Pendrin is a membrane transporter encoded by solute carrier family26A4 (SLC26A4). Mutations in this gene are known to cause hearing loss, and recent data from animal studies indicate a link between pendrin expression and hypertension; although, this association in humans is unclear. To clarify this issue, we investigated the influence of pendrin on blood pressure by analyzing demographic and biochemical data - including blood pressure and urinary electrolyte excretion - in patients with bi-allelic SLC26A4 mutations. Systolic and diastolic blood pressure and the left ventricular hypertrophy index were lower in subjects with pendrin mutations than in controls. In addition, fractional excretion of Na+ and Cl- was increased and serum renin, angiotensin I and II levels were higher in subjects with pendrin mutations as compared to controls. Thus, patients with impaired pendrin function are likely to be resistant to high blood pressure due to enhanced urinary Na+ /Cl- excretion. These results suggest that pendrin may regulate blood pressure through increased urinary salt excretion.
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Affiliation(s)
- B G Kim
- Department of Otorhinolaryngology-Head and Neck Surgery, Soonchunhyang University, College of Medicine, Bucheon, Korea
| | - T-H Yoo
- Department of Internal Medicine, Yonsei University, College of Medicine, Seoul, Korea
| | - J-E Yoo
- Department of Otorhinolaryngology, Yonsei University, College of Medicine, Seoul, Korea
| | - Y J Seo
- Department of Otorhinolaryngology, Yonsei University, WonJu College of Medicine, Wonju, Korea
| | - J Jung
- Department of Otorhinolaryngology, Yonsei University, College of Medicine, Seoul, Korea
| | - J Y Choi
- Department of Otorhinolaryngology, Yonsei University, College of Medicine, Seoul, Korea
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Takabe S, Inokuchi M, Yamaguchi Y, Hyodo S. Distribution and dynamics of branchial ionocytes in houndshark reared in full-strength and diluted seawater environments. Comp Biochem Physiol A Mol Integr Physiol 2016; 198:22-32. [PMID: 27040185 DOI: 10.1016/j.cbpa.2016.03.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 03/18/2016] [Accepted: 03/23/2016] [Indexed: 12/22/2022]
Abstract
In teleost fishes, it is well-established that the gill serves as an important ionoregulatory organ in addition to its primary function of respiratory gas exchange. In elasmobranchs, however, the ionoregulatory function of the gills is still incompletely understood. Although two types of ionocytes, Na(+)/K(+)-ATPase (NKA)-rich (type-A) cell and vacuolar-type H(+)-ATPase (V-ATPase)-rich (type-B) cell, have been found in elasmobranch fishes, these cells were considered to function primarily in acid-base regulation. In the present study, we examined ion-transporting proteins expressed in ionocytes of Japanese-banded houndshark, Triakis scyllium, reared in full-strength seawater (SW) and transferred to diluted (30%) SW. In addition to the upregulation of NKA and Na(+)/H(+) exchanger type 3 (NHE3) mRNAs in the type-A ionocytes, we found that Na(+), Cl(-) cotransporter (NCC, Slc12a3) is expressed in a subpopulation of the type-B ionocytes, and that the expression level of NCC mRNA was enhanced in houndsharks transferred to a low-salinity environment. These results suggest that elasmobranch gill ionocytes contribute to NaCl uptake in addition to the already described function of acid-base regulation, and that NCC is most probably one of the key molecules for hyper-osmoregulatory function of elasmobranch gills. The existence of two types of ionocytes (NHE3- and NCC-expressing cells) that are responsible for NaCl absorption seems to be a common feature in both teleosts and elasmobranchs for adaptation to a low salinity environment. A possible driving mechanism for NCC in type-B ionocytes is discussed.
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Affiliation(s)
- Souichirou Takabe
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan.
| | - Mayu Inokuchi
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
| | - Yoko Yamaguchi
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan; Hawai'i Institute of Marine Biology, University of Hawai'i, 46-007 Lilipuna Road, Kaneohe, HI 96744, USA
| | - Susumu Hyodo
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
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The Role of Epithelial Sodium Channel ENaC and the Apical Cl-/HCO3- Exchanger Pendrin in Compensatory Salt Reabsorption in the Setting of Na-Cl Cotransporter (NCC) Inactivation. PLoS One 2016; 11:e0150918. [PMID: 26963391 PMCID: PMC4786216 DOI: 10.1371/journal.pone.0150918] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 02/18/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The absence of NCC does not cause significant salt wasting in NCC deficient mice under basal conditions. We hypothesized that ENaC and pendrin play important roles in compensatory salt absorption in the setting of NCC inactivation, and their inhibition and/or downregulation can cause significant salt wasting in NCC KO mice. METHODS WT and NCC KO mice were treated with a daily injection of either amiloride, an inhibitor of ENaC, or acetazolamide (ACTZ), a blocker of salt and bicarbonate reabsorption in the proximal tubule and an inhibitor of carbonic anhydrases in proximal tubule and intercalated cells, or a combination of acetazolamide plus amiloride for defined durations. Animals were subjected to daily balance studies. At the end of treatment, kidneys were harvested and examined. Blood samples were collected for electrolytes and acid base analysis. RESULTS Amiloride injection significantly increased the urine output (UO) in NCC KO mice (from 1.3 ml/day before to 2.5 ml/day after amiloride, p<0.03, n = 4) but caused only a slight change in UO in WT mice (p>0.05). The increase in UO in NCC KO mice was associated with a significant increase in sodium excretion (from 0.25 mmol/24 hrs at baseline to 0.35 mmol/24 hrs after amiloride injection, p<0.05, n = 4). Daily treatment with ACTZ for 6 days resulted in >80% reduction of kidney pendrin expression in both WT and NCC KO mice. However, ACTZ treatment noticeably increased urine output and salt excretion only in NCC KO mice (with urine output increasing from a baseline of 1.1 ml/day to 2.3 ml/day and sodium excretion increasing from 0.22 mmole/day before to 0.31 mmole/day after ACTZ) in NCC KO mice; both parameters were significantly higher than in WT mice. Western blot analysis demonstrated significant enhancement in ENaC expression in medulla and cortex of NCC KO and WT mice in response to ACTZ injection for 6 days, and treatment with amiloride in ACTZ-pretreated mice caused a robust increase in salt excretion in both NCC KO and WT mice. Pendrin KO mice did not display a significant increase in urine output or salt excretion after treatment with amiloride or ACTZ. CONCLUSION 1. ENaC plays an important role in salt reabsorption in NCC KO mice. 2. NCC contributes to compensatory salt reabsorption in the setting of carbonic anhydrase inhibition, which is associated with increased delivery of salt from the proximal tubule and the down regulation of pendrin. 3. ENaC is upregulated by ACTZ treatment and its inhibition by amiloride causes significant diuresis in NCC KO and WT mice. Despite being considered mild agents individually, we propose that the combination of acetazolamide and amiloride in the setting of NCC inhibition (i.e., hydrochlorothiazide) will be a powerful diuretic regimen.
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Haggie PM, Phuan PW, Tan JA, Zlock L, Finkbeiner WE, Verkman AS. Inhibitors of pendrin anion exchange identified in a small molecule screen increase airway surface liquid volume in cystic fibrosis. FASEB J 2016; 30:2187-97. [PMID: 26932931 DOI: 10.1096/fj.201600223r] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 02/06/2016] [Indexed: 12/31/2022]
Abstract
Pendrin (SLC26A4) is a Cl(-)/anion exchanger expressed in the epithelium of inflamed airways where it is thought to facilitate Cl(-) absorption and HCO3 (-) secretion. Studies using pendrin knockout mice and airway epithelial cells from hearing-impaired subjects with pendrin loss of function suggest involvement of pendrin in inflammatory lung diseases, including cystic fibrosis (CF), perhaps by regulation of airway surface liquid (ASL) volume. Here we identified small-molecule pendrin inhibitors and demonstrated their efficacy in increasing ASL volume. A cell-based, functional high-throughput screen of ∼36,000 synthetic small molecules produced 3 chemical classes of inhibitors of human pendrin. After structure-activity studies, tetrahydropyrazolopyridine and pyrazolothiophenesulfonamide compounds reversibly inhibited pendrin-facilitated Cl(-) exchange with SCN(-), I(-), NO3 (-), and HCO3 (-) with drug concentration causing 50% inhibition down to ∼2.5 μM. In well-differentiated primary cultures of human airway epithelial cells from non-CF and CF subjects, treatment with IL-13, which causes inflammation with strong pendrin up-regulation, strongly increased Cl(-)/HCO3 (-) exchange and the increase was blocked by pendrin inhibition. Pendrin inhibition significantly increased ASL depth (by ∼8 μm) in IL-13-treated non-CF and CF cells but not in untreated cells. These studies implicate the involvement of pendrin-facilitated Cl(-)/HCO3 (-) in the regulation of ASL volume and suggest the utility of pendrin inhibitors in inflammatory lung diseases, including CF.-Haggie, P. M., Phuan, P.-W., Tan, J.-A., Zlock, L., Finkbeiner, W. E., Verkman, A. S. Inhibitors of pendrin anion exchange identified in a small molecule screen increase airway surface liquid volume in cystic fibrosis.
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Affiliation(s)
- Peter M Haggie
- Department of Medicine, University of California, San Francisco, San Francisco, California, USA; Department of Physiology, University of California, San Francisco, San Francisco, California, USA; and
| | - Puay-Wah Phuan
- Department of Medicine, University of California, San Francisco, San Francisco, California, USA; Department of Physiology, University of California, San Francisco, San Francisco, California, USA; and
| | - Joseph-Anthony Tan
- Department of Medicine, University of California, San Francisco, San Francisco, California, USA; Department of Physiology, University of California, San Francisco, San Francisco, California, USA; and
| | - Lorna Zlock
- Department of Pathology, University of California, San Francisco, San Francisco, California, USA
| | - Walter E Finkbeiner
- Department of Pathology, University of California, San Francisco, San Francisco, California, USA
| | - A S Verkman
- Department of Medicine, University of California, San Francisco, San Francisco, California, USA; Department of Physiology, University of California, San Francisco, San Francisco, California, USA; and
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Abstract
Pendrin is a Na(+)-independent Cl(-)/HCO3(-) exchanger found in the apical regions of type B and non-A, non-B intercalated cells within the aldosterone-sensitive region of the nephron, i.e., the distal convoluted tubule (DCT), the connecting tubule (CNT), and the cortical collecting duct (CCD). Type B intercalated cells mediate Cl(-) absorption and HCO3(-) secretion primarily through pendrin-mediated Cl(-)/HCO3(-) exchange. This exchanger is upregulated with angiotensin II administration and in models of metabolic alkalosis, such as following administration of aldosterone or NaHCO3. In the absence of pendrin-mediated HCO3(-) secretion, an enhanced alkalosis is observed following aldosterone or NaHCO3 administration. However, probably of more significance is the role of pendrin in the pressor response to aldosterone. Pendrin mediates Cl(-) absorption and modulates aldosterone-induced Na(+) absorption mediated by the epithelial Na channel (ENaC). Pendrin changes ENaC activity by changing both channel open probability (Po) and surface density (N), at least partly by altering luminal HCO3(-) and ATP concentration. Thus aldosterone and angiotensin II stimulate pendrin expression and function, which stimulates ENaC activity, thereby contributing to the pressor response of these hormones. However, pendrin may modulate blood pressure partly through its extrarenal effects. For example, pendrin is expressed in the adrenal medulla, where it modulates catecholamine release. The increase in catecholamine release observed with pendrin gene ablation likely contributes to the increment in vascular contractile force observed in the pendrin null mouse. This review summarizes the signaling mechanisms that regulate pendrin abundance and function as well as the contribution of pendrin to distal nephron function.
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Affiliation(s)
- Susan M Wall
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; and Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
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Effect of SLC26 anion transporter disease-causing mutations on the stability of the homologous STAS domain of E. coli DauA (YchM). Biochem J 2015; 473:615-26. [PMID: 26635355 DOI: 10.1042/bj20151025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 12/03/2015] [Indexed: 01/08/2023]
Abstract
The human solute carrier 26 (SLC26) family of anion transporters consists of ten members that are found in various organs in the body including the stomach, intestine, kidney, thyroid and ear where they transport anions including bicarbonate, chloride and sulfate, typically in an exchange mode. Mutations in these genes cause a plethora of diseases such as diastrophic dysplasia affecting sulfate uptake into chondrocytes (SLC26A2), congenital chloride-losing diarrhoea (SLC26A3) affecting chloride secretion in the intestine and Pendred's syndrome (SLC26A4) resulting in hearing loss. To understand how these mutations affect the structures of the SLC26 membrane proteins and their ability to function properly, 12 human disease-causing mutants from SLC26A2, SLC26A3 and SLC26A4 were introduced into the equivalent sites of the sulfate transporter anti-sigma factor antagonist (STAS) domain of a bacterial homologue SLC26 protein DauA (YchM). Biophysical analyses including size-exclusion chromatography, circular dichroism (CD), differential scanning fluorimetry (DSF) and tryptophan fluorescence revealed that most mutations caused protein instability and aggregation. The mutation A463K, equivalent to N558K in human SLC26A4, which is located within α-helix 1 of the DauA STAS domain, stabilized the protein. CD measurements showed that most disease-related mutants had a mildly reduced helix content, but were more sensitive to thermal denaturation. Fluorescence spectroscopy showed that the mutants had more open structures and were more readily denatured by urea, whereas DSF indicated more labile folds. Overall, we conclude that the disease-associated mutations destabilized the STAS domain resulting in an increased propensity to misfold and aggregate.
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Abstract
Pendrin is a Na(+)-independent Cl(-)/HCO3(-) exchanger that localizes to type B and non-A, non-B intercalated cells, which are expressed within the aldosterone-sensitive region of the nephron, i.e., the distal convoluted tubule, the connecting tubule, and the cortical collecting duct. Type B cells mediate Cl(-) absorption and HCO3(-) secretion primarily through pendrin-mediated Cl(-)/HCO3(-) exchange. At least in some treatment models, pendrin acts in tandem with the Na(+)-dependent Cl(-)/HCO3(-) exchanger (NDCBE) encoded by Slc4a8 to mediate NaCl absorption. The pendrin-mediated Cl(-)/HCO3(-) exchange process is greatly upregulated in models of metabolic alkalosis, such as following aldosterone administration or dietary NaHCO3 loading. It is also upregulated by angiotensin II. In the absence of pendrin [Slc26a4 (-/-) or pendrin null mice], aldosterone-stimulated NaCl absorption is reduced, which lowers the blood pressure response to aldosterone and enhances the alkalosis that follows the administration of this steroid hormone. Pendrin modulates aldosterone-induced Na(+) absorption by changing ENaC abundance and function through a kidney-specific mechanism that does not involve changes in the concentration of a circulating hormone. Instead, pendrin changes ENaC abundance and function at least in part by altering luminal HCO3(-) and ATP concentrations. Thus, aldosterone and angiotensin II also stimulate pendrin expression and function, which likely contributes to the pressor response of these hormones. This review summarizes the contribution of the Cl(-)/HCO3(-) exchanger pendrin in distal nephron function.
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48
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Potential treatments for genetic hearing loss in humans: current conundrums. Gene Ther 2015; 22:603-9. [PMID: 25781649 DOI: 10.1038/gt.2015.27] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 01/24/2015] [Accepted: 02/12/2015] [Indexed: 12/18/2022]
Abstract
Genetic defects are a major cause of hearing loss in newborns. Consequently, hearing loss has a profound negative impact on human daily living. Numerous causative genes for genetic hearing loss have been identified. However, presently, there are no truly curative treatments for this condition. There have been several recent reports on successful treatments in mice using embryonic gene therapy, neonatal gene therapy and neonatal antisense oligonucleotide therapy. Herein, we describe state-of-the-art research on genetic hearing loss treatment through gene therapy and discuss the obstacles to overcome in curative treatments of genetic hearing loss in humans.
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Fang SC, Chung CL, Chen CH, Lopez-Paz C, Umen JG. Defects in a new class of sulfate/anion transporter link sulfur acclimation responses to intracellular glutathione levels and cell cycle control. PLANT PHYSIOLOGY 2014; 166:1852-68. [PMID: 25361960 PMCID: PMC4256884 DOI: 10.1104/pp.114.251009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 10/29/2014] [Indexed: 05/18/2023]
Abstract
We previously identified a mutation, suppressor of mating type locus3 15-1 (smt15-1), that partially suppresses the cell cycle defects caused by loss of the retinoblastoma tumor suppressor-related protein encoded by the MAT3 gene in Chlamydomonas reinhardtii. smt15-1 single mutants were also found to have a cell cycle defect leading to a small-cell phenotype. SMT15 belongs to a previously uncharacterized subfamily of putative membrane-localized sulfate/anion transporters that contain a sulfate transporter domain and are found in a widely distributed subset of eukaryotes and bacteria. Although we observed that smt15-1 has a defect in acclimation to sulfur-limited growth conditions, sulfur acclimation (sac) mutants, which are more severely defective for acclimation to sulfur limitation, do not have cell cycle defects and cannot suppress mat3. Moreover, we found that smt15-1, but not sac mutants, overaccumulates glutathione. In wild-type cells, glutathione fluctuated during the cell cycle, with highest levels in mid G1 phase and lower levels during S and M phases, while in smt15-1, glutathione levels remained elevated during S and M. In addition to increased total glutathione levels, smt15-1 cells had an increased reduced-to-oxidized glutathione redox ratio throughout the cell cycle. These data suggest a role for SMT15 in maintaining glutathione homeostasis that impacts the cell cycle and sulfur acclimation responses.
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Affiliation(s)
- Su-Chiung Fang
- Biotechnology Center in Southern Taiwan, Academia Sinica, Tainan County 741, Taiwan (S.-C.F., C.-L.C., C.-H.C.);Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan (S.-C.F., C.-L.C., C.-H.C.);Institute of Marine Biotechnology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (C.-L.C.); andDonald Danforth Plant Science Center, St. Louis, Missouri 63132 (C.L.-P., J.G.U.)
| | - Chin-Lin Chung
- Biotechnology Center in Southern Taiwan, Academia Sinica, Tainan County 741, Taiwan (S.-C.F., C.-L.C., C.-H.C.);Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan (S.-C.F., C.-L.C., C.-H.C.);Institute of Marine Biotechnology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (C.-L.C.); andDonald Danforth Plant Science Center, St. Louis, Missouri 63132 (C.L.-P., J.G.U.)
| | - Chun-Han Chen
- Biotechnology Center in Southern Taiwan, Academia Sinica, Tainan County 741, Taiwan (S.-C.F., C.-L.C., C.-H.C.);Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan (S.-C.F., C.-L.C., C.-H.C.);Institute of Marine Biotechnology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (C.-L.C.); andDonald Danforth Plant Science Center, St. Louis, Missouri 63132 (C.L.-P., J.G.U.)
| | - Cristina Lopez-Paz
- Biotechnology Center in Southern Taiwan, Academia Sinica, Tainan County 741, Taiwan (S.-C.F., C.-L.C., C.-H.C.);Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan (S.-C.F., C.-L.C., C.-H.C.);Institute of Marine Biotechnology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (C.-L.C.); andDonald Danforth Plant Science Center, St. Louis, Missouri 63132 (C.L.-P., J.G.U.)
| | - James G Umen
- Biotechnology Center in Southern Taiwan, Academia Sinica, Tainan County 741, Taiwan (S.-C.F., C.-L.C., C.-H.C.);Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan (S.-C.F., C.-L.C., C.-H.C.);Institute of Marine Biotechnology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (C.-L.C.); andDonald Danforth Plant Science Center, St. Louis, Missouri 63132 (C.L.-P., J.G.U.)
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Yamazaki H, Naito Y, Moroto S, Tamaya R, Yamazaki T, Fujiwara K, Ito J. SLC26A4 p.Thr410Met homozygous mutation in a patient with a cystic cochlea and an enlarged vestibular aqueduct showing characteristic features of incomplete partition type I and II. Int J Pediatr Otorhinolaryngol 2014; 78:2322-6. [PMID: 25468468 DOI: 10.1016/j.ijporl.2014.10.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 10/21/2014] [Accepted: 10/29/2014] [Indexed: 11/16/2022]
Abstract
Mutations of SLC26A4 are associated with incomplete partition type II (IP-II) and isolated enlargement of the vestibular aqueduct (EVA). We experienced a congenitally deaf 6-year-old boy with a rare p.Thr410Met homozygous mutation in SLC26A4 who underwent bilateral cochlear implantation. He had bilateral inner ear malformation, in which the dilated vestibule and EVA were identical to those in IP-II, but the cochlea lacking a bony modiolus resembled that in incomplete partition type I. These results suggest that homozygous mutations in SLC26A4 are always associated with EVA, while the severity of cochlear malformation may vary depending on the type of SLC26A4 mutation.
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Affiliation(s)
- Hiroshi Yamazaki
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
| | - Yasushi Naito
- Department of Otolaryngology, Kobe City Medical Center General Hospital, Kobe, Japan
| | - Saburo Moroto
- Department of Otolaryngology, Kobe City Medical Center General Hospital, Kobe, Japan
| | - Rinko Tamaya
- Department of Otolaryngology, Kobe City Medical Center General Hospital, Kobe, Japan
| | - Tomoko Yamazaki
- Department of Otolaryngology, Kobe City Medical Center General Hospital, Kobe, Japan
| | - Keizo Fujiwara
- Department of Otolaryngology, Kobe City Medical Center General Hospital, Kobe, Japan
| | - Juichi Ito
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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