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“Reversed polarization” of Na/K-ATPase—a sign of inverted transport in the human endolymphatic sac: a super-resolution structured illumination microscopy (SR-SIM) study. Cell Tissue Res 2019; 379:445-457. [DOI: 10.1007/s00441-019-03106-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 09/15/2019] [Indexed: 02/06/2023]
Abstract
AbstractThe human endolymphatic sac (ES) is believed to regulate inner ear fluid homeostasis and to be associated with Meniere’s disease (MD). We analyzed the ion transport protein sodium/potassium-ATPase (Na/K-ATPase) and its isoforms in the human ES using super-resolution structured illumination microscopy (SR-SIM). Human vestibular aqueducts were collected during trans-labyrinthine vestibular schwannoma surgery after obtaining ethical permission. Antibodies against various isoforms of Na/K-ATPase and additional solute-transporting proteins, believed to be essential for ion and fluid transport, were used for immunohistochemistry. A population of epithelial cells of the human ES strongly expressed Na/K-ATPase α1, β1, and β3 subunit isoforms in either the lateral/basolateral or apical plasma membrane domains. The β1 isoform was expressed in the lateral/basolateral plasma membranes in mostly large cylindrical cells, while β3 and α1 both were expressed with “reversed polarity” in the apical cell membrane in lower epithelial cells. The heterogeneous expression of Na/K-ATPase subunits substantiates earlier notions that the ES is a dynamic structure where epithelial cells show inverted epithelial transport. Dual absorption and secretion processes may regulate and maintain inner ear fluid homeostasis. These findings may shed new light on the etiology of endolymphatic hydrops and MD.
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Kim SH, Nam GS, Choi JY. Pathophysiologic Findings in the Human Endolymphatic Sac in Endolymphatic Hydrops: Functional and Molecular Evidence. Ann Otol Rhinol Laryngol 2019; 128:76S-83S. [PMID: 31092029 DOI: 10.1177/0003489419837993] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The endolymphatic sac (ES) is a cystic structure situated on the posterior fossa dura and is connected to the luminal space of the vestibular organ through the endolymphatic duct, which branches into the utricular and saccular ducts. Unlike the cochlea and vestibule, the ES does not contain sensory epithelium in its luminal space, and a single layer of epithelial cells line the luminal surface area. The ES in the inner ear is thought to play a role in the regulation of inner ear homeostasis, fluid volume, and immune reaction. If these functions of the ES are disrupted, dysfunction of the inner ear may develop. The most well-known pathology arising from dysfunction of the ES is endolymphatic hydrops, characterized by an enlarged endolymphatic space due to the accumulation of excessive endolymphatic fluid. Although, molecular identities and functional evidence for the roles were identified in animal studies, basic studies of the human ES are relatively uncommon compared with those using animal tissues, because of limited opportunity to harvest the human ES. METHODS In this study, molecular and functional evidence for the role of the human ES in the development of endolymphatic hydrops are reviewed. RESULTS AND CONCLUSIONS Although evidence is insufficient, studies using the human ES have mostly produced findings similar to those of animal studies. This review may provide a basis for planning further studies to investigate the pathophysiology of disorders with the finding of endolymphatic hydrops.
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Affiliation(s)
- Sung Huhn Kim
- 1 Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Republic of Korea.,2 The Airway Mucus Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Gi-Sung Nam
- 1 Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jae Young Choi
- 1 Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Republic of Korea.,2 The Airway Mucus Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
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Honda K, Kim SH, Kelly MC, Burns JC, Constance L, Li X, Zhou F, Hoa M, Kelley MW, Wangemann P, Morell RJ, Griffith AJ. Molecular architecture underlying fluid absorption by the developing inner ear. eLife 2017; 6. [PMID: 28994389 PMCID: PMC5634787 DOI: 10.7554/elife.26851] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 09/10/2017] [Indexed: 12/26/2022] Open
Abstract
Mutations of SLC26A4 are a common cause of hearing loss associated with enlargement of the endolymphatic sac (EES). Slc26a4 expression in the developing mouse endolymphatic sac is required for acquisition of normal inner ear structure and function. Here, we show that the mouse endolymphatic sac absorbs fluid in an SLC26A4-dependent fashion. Fluid absorption was sensitive to ouabain and gadolinium but insensitive to benzamil, bafilomycin and S3226. Single-cell RNA-seq analysis of pre- and postnatal endolymphatic sacs demonstrates two types of differentiated cells. Early ribosome-rich cells (RRCs) have a transcriptomic signature suggesting expression and secretion of extracellular proteins, while mature RRCs express genes implicated in innate immunity. The transcriptomic signature of mitochondria-rich cells (MRCs) indicates that they mediate vectorial ion transport. We propose a molecular mechanism for resorption of NaCl by MRCs during development, and conclude that disruption of this mechanism is the root cause of hearing loss associated with EES.
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Affiliation(s)
- Keiji Honda
- Molecular Biology and Genetics Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Sung Huhn Kim
- Anatomy and Physiology Department, Kansas State University, Manhattan, United States
| | - Michael C Kelly
- Developmental Neuroscience Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Joseph C Burns
- Developmental Neuroscience Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Laura Constance
- Anatomy and Physiology Department, Kansas State University, Manhattan, United States
| | - Xiangming Li
- Anatomy and Physiology Department, Kansas State University, Manhattan, United States
| | - Fei Zhou
- Anatomy and Physiology Department, Kansas State University, Manhattan, United States
| | - Michael Hoa
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Matthew W Kelley
- Developmental Neuroscience Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Philine Wangemann
- Anatomy and Physiology Department, Kansas State University, Manhattan, United States
| | - Robert J Morell
- Genomics and Computational Biology Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Andrew J Griffith
- Molecular Biology and Genetics Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
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Runggaldier D, Pradas LG, Neckel PH, Mack AF, Hirt B, Gleiser C. Claudin expression in the rat endolymphatic duct and sac - first insights into regulation of the paracellular barrier by vasopressin. Sci Rep 2017; 7:45482. [PMID: 28374851 PMCID: PMC5379655 DOI: 10.1038/srep45482] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 02/28/2017] [Indexed: 12/13/2022] Open
Abstract
Hearing and balance functions of the inner ear rely on the homeostasis of the endolymphatic fluid. When disturbed, pathologic endolymphatic hydrops evolves as observed in Menière’s disease. The molecular basis of inner ear fluid regulation across the endolymphatic epithelium is largely unknown. In this study we identified the specific expression of the tight junction (TJ) molecules Claudin 3, 4, 6, 7, 8, 10, and 16 in epithelial preparations of the rat inner ear endolymphatic duct (ED) and endolymphatic sac (ES) by high-throughput qPCR and immunofluorescence confocal microscopy. Further we showed that Claudin 4 in the ES is a target of arginine-vasopressin (AVP), a hormone elevated in Menière’s disease. Moreover, our transmission-electron microscopy (TEM) analysis revealed that the TJs of the ED were shallow and shorter compared to the TJ of the ES indicating facilitation of a paracellular fluid transport across the ED epithelium. The significant differences in the subcellular localization of the barrier-forming protein Claudin 3 between the ED and ES epithelium further support the TEM observations. Our results indicate a high relevance of Claudin 3 and Claudin 4 as important paracellular barrier molecules in the ED and ES epithelium with potential involvement in the pathophysiology of Menière’s disease.
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Affiliation(s)
- Daniel Runggaldier
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
| | - Lidia Garcia Pradas
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
| | - Peter H Neckel
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
| | - Andreas F Mack
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
| | - Bernhard Hirt
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
| | - Corinna Gleiser
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
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He L, Huang N, Li H, Tian J, Zhou X, Li T, Yao K, Wu G, Yin Y. AMPK/α-Ketoglutarate Axis Regulates Intestinal Water and Ion Homeostasis in Young Pigs. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2017; 65:2287-2298. [PMID: 28241728 DOI: 10.1021/acs.jafc.7b00324] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Water and ion absorption via sensitive aquaporins (AQPs) and ion channels is of critical importance in intestinal health. However, whether α-ketoglutarate (AKG) could improve intestinal water and ion homeostasis in lipopolysaccharide (LPS)-challenged piglets and whether the AMP-activated protein kinase (AMPK) pathway is involved remains largely unknown. This study was conducted to investigate the effect of dietary AKG supplementation on the small intestinal water and ion homeostasis through modulating the AMPK pathway in a piglet diarrhea model. A total of 32 weaned piglets were used in a 2 × 2 factorial design; the major factors were diet (basal diet or 1% AKG diet) and challenge (Escherichia coli LPS or saline). The results showed that LPS challenge increased the diarrhea index and affected the concentrations of serum Na+, K+, Cl-, glucose, and AKG and its metabolites in piglets fed the basal or AKG diet. However, the addition of AKG attenuated diarrhea incidence and reversed these serum parameter concentrations. Most AQPs (e.g., AQP1, AQP3, AQP4, AQP5, AQP8, AQP10, and AQP11) and ion transporters (NHE3, ENaC, and DRA/PAT1) were widely distributed in the duodenum and jejunum of piglets. We also found that AKG up-regulated the expression of intestinal epithelial AQPs while inhibiting the expression of ion transporters. LPS challenge decreased (P < 0.05) the gene and protein expression of the AMPK pathway (AMPKα1, AMPKα2, SIRT1, PGC-1α, ACC, and TORC2) in the jejunum and ileum. Notably, AKG supplementation enhanced the abundance of these proteins in the LPS-challenged piglets. Collectively, AKG plays an important role in increasing water and ion homeostasis through modulating the AMPK pathway. Our novel finding has important implications for the prevention and treatment of gut dysfunction in neonates.
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Affiliation(s)
- Liuqin He
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production , Changsha, Hunan 410125, China
- University of the Chinese Academy of Sciences , Beijing 10008, China
| | - Niu Huang
- College of Animal Science and Technology, Hunan Agricultural University , Changsha, Hunan 410128, China
| | - Huan Li
- College of Animal Science and Technology, Hunan Agricultural University , Changsha, Hunan 410128, China
| | - Junquan Tian
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production , Changsha, Hunan 410125, China
- University of the Chinese Academy of Sciences , Beijing 10008, China
| | - Xihong Zhou
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production , Changsha, Hunan 410125, China
| | - Tiejun Li
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production , Changsha, Hunan 410125, China
| | - Kang Yao
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production , Changsha, Hunan 410125, China
- College of Animal Science and Technology, Hunan Agricultural University , Changsha, Hunan 410128, China
| | - Guoyao Wu
- Department of Animal Science, Texas A&M University , College Station, Texas 77843, United States
| | - Yulong Yin
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production , Changsha, Hunan 410125, China
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Kim BG, Kim JY, Jung J, Moon IS, Yoon JH, Choi JY, Kim SH. β 1- and β 2-adrenergic stimulation-induced electrogenic transport by human endolymphatic sac epithelium and its clinical implications. Sci Rep 2017; 7:42217. [PMID: 28165045 PMCID: PMC5292703 DOI: 10.1038/srep42217] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 01/03/2017] [Indexed: 01/02/2023] Open
Abstract
The endolymphatic sac (ES) is a cystic structure of the inner ear connected to the cochlea and vestibule, which plays a role in regulating ion homeostasis in inner ear fluid. Disruption of ion homeostasis can cause inner ear disorders with hearing loss and dizziness, such as Meniere's disease. Herein, we found, for the first time, functional evidence for the involvement of β1- and β2-adrenergic receptors in apical electrogenic ion transport by human ES epithelium by using electrophysiological/pharmacological and molecular biological methods, which were dependent on K+ and Cl- ion transport. The apical electrogenic transport was absent or very weak in ES epithelia of patients with Meniere's disease. These results suggested that adrenergic stimulation via β1- and β2-adrenergic receptors in the human ES was involved in regulation of inner ear fluid ion homeostasis and impairment of this response could be a pathological mechanism of Meniere's disease.
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Affiliation(s)
- Bo Gyung Kim
- Department of Otorhinolaryngology, Soonchunhyang University College of Medicine, Bucheon, 420-767, Republic of Korea
| | - Jin Young Kim
- Research Center for Natural Human Defense System, Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Republic of Korea
| | - JinSei Jung
- Department of Otorhinolaryngology, Yonsei University College of Medicine
| | - In Seok Moon
- Department of Otorhinolaryngology, Yonsei University College of Medicine
| | - Joo-Heon Yoon
- Research Center for Natural Human Defense System, Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Republic of Korea.,Department of Otorhinolaryngology, Yonsei University College of Medicine.,The Airway Mucus Institute, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
| | - Jae Young Choi
- Department of Otorhinolaryngology, Yonsei University College of Medicine.,The Airway Mucus Institute, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
| | - Sung Huhn Kim
- Department of Otorhinolaryngology, Yonsei University College of Medicine.,The Airway Mucus Institute, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
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Ion transport its regulation in the endolymphatic sac: suggestions for clinical aspects of Meniere's disease. Eur Arch Otorhinolaryngol 2016; 274:1813-1820. [PMID: 27804084 PMCID: PMC5340852 DOI: 10.1007/s00405-016-4362-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Accepted: 10/26/2016] [Indexed: 01/22/2023]
Abstract
Ion transport and its regulation in the endolymphatic sac (ES) are reviewed on the basis of recent lines of evidence. The morphological and physiological findings demonstrate that epithelial cells in the intermediate portion of the ES are more functional in ion transport than those in the other portions. Several ion channels, ion transporters, ion exchangers, and so on have been reported to be present in epithelial cells of ES intermediate portion. An imaging study has shown that mitochondria-rich cells in the ES intermediate portion have a higher activity of Na+, K+-ATPase and a higher Na+ permeability than other type of cells, implying that molecules related to Na+ transport, such as epithelial sodium channel (ENaC), Na+–K+–2Cl− cotransporter 2 (NKCC2) and thiazide-sensitive Na+–Cl− cotransporter (NCC), may be present in mitochondria-rich cells. Accumulated lines of evidence suggests that Na+ transport is most important in the ES, and that mitochondria-rich cells play crucial roles in Na+ transport in the ES. Several lines of evidence support the hypothesis that aldosterone may regulate Na+ transport in ES, resulting in endolymph volume regulation. The presence of molecules related to acid/base transport, such as H+-ATPase, Na+–H+ exchanger (NHE), pendrin (SLC26A4), Cl−–HCO3− exchanger (SLC4A2), and carbonic anhydrase in ES epithelial cells, suggests that acid/base transport is another important one in the ES. Recent basic and clinical studies suggest that aldosterone may be involved in the effect of salt-reduced diet treatment in Meniere’s disease.
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