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Almalki F. Review and research gap identification in genetics causes of syndromic and nonsyndromic hearing loss in Saudi Arabia. Ann Hum Genet 2024. [PMID: 38517009 DOI: 10.1111/ahg.12559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 02/13/2024] [Accepted: 03/04/2024] [Indexed: 03/23/2024]
Abstract
Congenital hearing loss is one of the most common sensory disabilities worldwide. The genetic causes of hearing loss account for 50% of hearing loss. Genetic causes of hearing loss can be classified as nonsyndromic hearing loss (NSHL) or syndromic hearing loss (SHL). NSHL is defined as a partial or complete hearing loss without additional phenotypes; however, SHL, known as hearing loss, is associated with other phenotypes. Both types follow a simple Mendelian inheritance fashion. Several studies have been conducted to uncover the genetic factors contributing to NSHL and SHL in Saudi patients. However, these studies have encountered certain limitations. This review assesses and discusses the genetic factors underpinning NSHL and SHL globally, with a specific emphasis on the Saudi Arabian context. It also explores the prevalence of the most observed genetic causes of NSHL and SHL in Saudi Arabia. It also sheds light on areas where further research is needed to fully understand the genetic foundations of hearing loss in the Saudi population. This review identifies several gaps in research in NSHL and SHL and provides insights into potential research to be conducted.
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Affiliation(s)
- Faisal Almalki
- Medical Laboratories Technology Department, College of Applied Medical Sciences, Taibah University, Al Madinah Al Munwarah, Saudi Arabia
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2
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Posukh OL, Maslova EA, Danilchenko VY, Zytsar MV, Orishchenko KE. Functional Consequences of Pathogenic Variants of the GJB2 Gene (Cx26) Localized in Different Cx26 Domains. Biomolecules 2023; 13:1521. [PMID: 37892203 PMCID: PMC10604905 DOI: 10.3390/biom13101521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 10/08/2023] [Accepted: 10/10/2023] [Indexed: 10/29/2023] Open
Abstract
One of the most common forms of genetic deafness has been predominantly associated with pathogenic variants in the GJB2 gene, encoding transmembrane protein connexin 26 (Cx26). The Cx26 molecule consists of an N-terminal domain (NT), four transmembrane domains (TM1-TM4), two extracellular loops (EL1 and EL2), a cytoplasmic loop, and a C-terminus (CT). Pathogenic variants in the GJB2 gene, resulting in amino acid substitutions scattered across the Cx26 domains, lead to a variety of clinical outcomes, including the most common non-syndromic autosomal recessive deafness (DFNB1A), autosomal dominant deafness (DFNA3A), as well as syndromic forms combining hearing loss and skin disorders. However, for rare and poorly documented variants, information on the mode of inheritance is often lacking. Numerous in vitro studies have been conducted to elucidate the functional consequences of pathogenic GJB2 variants leading to amino acid substitutions in different domains of Cx26 protein. In this work, we summarized all available data on a mode of inheritance of pathogenic GJB2 variants leading to amino acid substitutions and reviewed published information on their functional effects, with an emphasis on their localization in certain Cx26 domains.
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Affiliation(s)
- Olga L. Posukh
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia; (E.A.M.); (V.Y.D.); (M.V.Z.); (K.E.O.)
- Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Ekaterina A. Maslova
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia; (E.A.M.); (V.Y.D.); (M.V.Z.); (K.E.O.)
- Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Valeriia Yu. Danilchenko
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia; (E.A.M.); (V.Y.D.); (M.V.Z.); (K.E.O.)
- Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Marina V. Zytsar
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia; (E.A.M.); (V.Y.D.); (M.V.Z.); (K.E.O.)
| | - Konstantin E. Orishchenko
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia; (E.A.M.); (V.Y.D.); (M.V.Z.); (K.E.O.)
- Novosibirsk State University, 630090 Novosibirsk, Russia
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3
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Petit C, Bonnet C, Safieddine S. Deafness: from genetic architecture to gene therapy. Nat Rev Genet 2023; 24:665-686. [PMID: 37173518 DOI: 10.1038/s41576-023-00597-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/27/2023] [Indexed: 05/15/2023]
Abstract
Progress in deciphering the genetic architecture of human sensorineural hearing impairment (SNHI) or loss, and multidisciplinary studies of mouse models, have led to the elucidation of the molecular mechanisms underlying auditory system function, primarily in the cochlea, the mammalian hearing organ. These studies have provided unparalleled insights into the pathophysiological processes involved in SNHI, paving the way for the development of inner-ear gene therapy based on gene replacement, gene augmentation or gene editing. The application of these approaches in preclinical studies over the past decade has highlighted key translational opportunities and challenges for achieving effective, safe and sustained inner-ear gene therapy to prevent or cure monogenic forms of SNHI and associated balance disorders.
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Affiliation(s)
- Christine Petit
- Institut Pasteur, Université Paris Cité, Inserm, Institut de l'Audition, F-75012, Paris, France.
- Collège de France, F-75005, Paris, France.
| | - Crystel Bonnet
- Institut Pasteur, Université Paris Cité, Inserm, Institut de l'Audition, F-75012, Paris, France
| | - Saaïd Safieddine
- Institut Pasteur, Université Paris Cité, Inserm, Institut de l'Audition, F-75012, Paris, France
- Centre National de la Recherche Scientifique, F-75016, Paris, France
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4
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Zong YJ, Liu XZ, Tu L, Sun Y. Cytomembrane Trafficking Pathways of Connexin 26, 30, and 43. Int J Mol Sci 2023; 24:10349. [PMID: 37373495 DOI: 10.3390/ijms241210349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 06/12/2023] [Accepted: 06/13/2023] [Indexed: 06/29/2023] Open
Abstract
The connexin gene family is the most prevalent gene that contributes to hearing loss. Connexins 26 and 30, encoded by GJB2 and GJB6, respectively, are the most abundantly expressed connexins in the inner ear. Connexin 43, which is encoded by GJA1, appears to be widely expressed in various organs, including the heart, skin, the brain, and the inner ear. The mutations that arise in GJB2, GJB6, and GJA1 can all result in comprehensive or non-comprehensive genetic deafness in newborns. As it is predicted that connexins include at least 20 isoforms in humans, the biosynthesis, structural composition, and degradation of connexins must be precisely regulated so that the gap junctions can properly operate. Certain mutations result in connexins possessing a faulty subcellular localization, failing to transport to the cell membrane and preventing gap junction formation, ultimately leading to connexin dysfunction and hearing loss. In this review, we provide a discussion of the transport models for connexin 43, connexins 30 and 26, mutations affecting trafficking pathways of these connexins, the existing controversies in the trafficking pathways of connexins, and the molecules involved in connexin trafficking and their functions. This review can contribute to a new way of understanding the etiological principles of connexin mutations and finding therapeutic strategies for hereditary deafness.
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Affiliation(s)
- Yan-Jun Zong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xiao-Zhou Liu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Lei Tu
- Division of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
- Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan 430022, China
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5
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Abbott AC, García IE, Villanelo F, Flores-Muñoz C, Ceriani R, Maripillán J, Novoa-Molina J, Figueroa-Cares C, Pérez-Acle T, Sáez JC, Sánchez HA, Martínez AD. Expression of KID syndromic mutation Cx26S17F produces hyperactive hemichannels in supporting cells of the organ of Corti. Front Cell Dev Biol 2023; 10:1071202. [PMID: 36699003 PMCID: PMC9868548 DOI: 10.3389/fcell.2022.1071202] [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: 10/15/2022] [Accepted: 12/15/2022] [Indexed: 01/11/2023] Open
Abstract
Some mutations in gap junction protein Connexin 26 (Cx26) lead to syndromic deafness, where hearing impairment is associated with skin disease, like in Keratitis Ichthyosis Deafness (KID) syndrome. This condition has been linked to hyperactivity of connexin hemichannels but this has never been demonstrated in cochlear tissue. Moreover, some KID mutants, like Cx26S17F, form hyperactive HCs only when co-expressed with other wild-type connexins. In this work, we evaluated the functional consequences of expressing a KID syndromic mutation, Cx26S17F, in the transgenic mouse cochlea and whether co-expression of Cx26S17F and Cx30 leads to the formation of hyperactive HCs. Indeed, we found that cochlear explants from a constitutive knock-in Cx26S17F mouse or conditional in vitro cochlear expression of Cx26S17F produces hyperactive HCs in supporting cells of the organ of Corti. These conditions also produce loss of hair cells stereocilia. In supporting cells, we found high co-localization between Cx26S17F and Cx30. The functional properties of HCs formed in cells co-expressing Cx26S17F and Cx30 were also studied in oocytes and HeLa cells. Under the recording conditions used in this study Cx26S17F did not form functional HCs and GJCs, but cells co-expressing Cx26S17F and Cx30 present hyperactive HCs insensitive to HCs blockers, Ca2+ and La3+, resulting in more Ca2+ influx and cellular damage. Molecular dynamic analysis of putative heteromeric HC formed by Cx26S17F and Cx30 presents alterations in extracellular Ca2+ binding sites. These results support that in KID syndrome, hyperactive HCs are formed by the interaction between Cx26S17F and Cx30 in supporting cells probably causing damage to hair cells associated to deafness.
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Affiliation(s)
- Ana C. Abbott
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile,Facultad de Medicina Veterinaria y Agronomía, Instituto de Ciencias Naturales, Universidad de las Américas, Viña del Mar, Chile
| | - Isaac E. García
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile,Laboratorio de Fisiología Molecular y Biofísica, Facultad de Odontología, Universidad de Valparaíso, Valparaíso, Chile,Centro de Investigaciones en Ciencias Odontológicas y Médicas, CICOM, Universidad de Valparaíso, Valparaíso, Chile
| | - Felipe Villanelo
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Santiago, Chile,Computational Biology Lab, Centro Basal Ciencia & Vida, Universidad San Sebastián, Santiago, Chile
| | - Carolina Flores-Muñoz
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Ricardo Ceriani
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile,Escuela de Química y Farmacia, Facultad de Farmacia, Universidad de Valparaíso, Valparaíso, Chile
| | - Jaime Maripillán
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Joel Novoa-Molina
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Cindel Figueroa-Cares
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Tomas Pérez-Acle
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Santiago, Chile,Computational Biology Lab, Centro Basal Ciencia & Vida, Universidad San Sebastián, Santiago, Chile
| | - Juan C. Sáez
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Helmuth A. Sánchez
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile,*Correspondence: Helmuth A. Sánchez, ; Agustín D. Martínez,
| | - Agustín D. Martínez
- Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile,*Correspondence: Helmuth A. Sánchez, ; Agustín D. Martínez,
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Connolly K, Gonzalez-Cordero A. Modelling inner ear development and disease using pluripotent stem cells - a pathway to new therapeutic strategies. Dis Model Mech 2022; 15:dmm049593. [PMID: 36331565 PMCID: PMC10621662 DOI: 10.1242/dmm.049593] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2023] Open
Abstract
The sensory epithelia of the mammalian inner ear enable sound and movement to be perceived. Damage to these epithelia can cause irreversible sensorineural hearing loss and vestibular dysfunction because they lack regenerative capacity. The human inner ear cannot be biopsied without causing permanent damage, significantly limiting the tissue samples available for research. Investigating disease pathology and therapeutic developments have therefore traditionally relied on animal models, which often cannot completely recapitulate the human otic systems. These challenges are now being partly addressed using induced pluripotent stem cell-derived cultures, which generate the sensory epithelial-like tissues of the inner ear. Here, we review how pluripotent stem cells have been used to produce two-dimensional and three-dimensional otic cultures, the strengths and limitations of these new approaches, and how they have been employed to investigate genetic and acquired forms of audiovestibular dysfunction. This Review provides an overview of the progress in pluripotent stem cell-derived otic cultures thus far, focusing on their applications in disease modelling and therapeutic trials. We survey their current limitations and future directions, highlighting their prospective utility for high-throughput drug screening and developing personalised medicine approaches.
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Affiliation(s)
- Keeva Connolly
- Stem Cell Medicine Group, Children's Medical Research Institute, Westmead, 2145 NSW, Australia
- School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Westmead, 2145 NSW, Australia
| | - Anai Gonzalez-Cordero
- Stem Cell Medicine Group, Children's Medical Research Institute, Westmead, 2145 NSW, Australia
- School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Westmead, 2145 NSW, Australia
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7
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Liu W, Rask-Andersen H. GJB2 and GJB6 gene transcripts in the human cochlea: A study using RNAscope, confocal, and super-resolution structured illumination microscopy. Front Mol Neurosci 2022; 15:973646. [PMID: 36204137 PMCID: PMC9530750 DOI: 10.3389/fnmol.2022.973646] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 08/01/2022] [Indexed: 11/26/2022] Open
Abstract
Background Gap junction (GJ) proteins, connexin26 and 30, are highly prevalent in the human cochlea (HC), where they are involved in transcellular signaling, metabolic supply, and fluid homeostasis. Their genes, GJB2 and GJB6, are both located at the DFNB1 locus on chromosome 13q12. Mutations in GJB2 may cause mild to profound non-syndromic deafness. Here, we analyzed for the first time the various expressions of GJB2 and GJB6 gene transcripts in the different cell networks in the HC using the RNAscope technique. Materials and methods Archival paraformaldehyde-fixed sections of surgically obtained HC were used to label single mRNA oligonucleotides using the sensitive multiplex RNAscope® technique with fluorescent-tagged probes. Positive and negative controls also included the localization of ATP1A1, ATP1A2, and KCNJ10 gene transcripts in order to validate the specificity of labeling. Results Confocal and super-resolution structured illumination microscopy (SR-SIM) detected single gene transcripts as brightly stained puncta. The GJB2 and GJB6 gene transcripts were distributed in the epithelial and connective tissue systems in all three cochlear turns. The largest number of GJB2 and GJB6 gene transcripts was in the outer sulcus, spiral ligament, and stria vascularis (SV). Oligonucleotides were present in the supporting cells of the organ of Corti (OC), spiral limbus fibrocytes, and the floor of the scala vestibuli. Multiplex gene data suggest that cells in the cochlear lateral wall contain either GJB2 or GJB6 gene transcripts or both. The GJB6, but not GJB2, gene transcripts were found in the intermediate cells but none were found in the marginal cells. There were no GJB2 or GJB6 gene transcripts found in the hair cells and only a few in the spiral ganglion cells. Conclusion Both GJB2 and GJB6 mRNA gene transcripts were localized in cells in the adult HC using RNAscope®in situ hybridization (ISH) and high resolution microscopy. Generally, GJB6 dominated over GJB2, except in the basal cells. Results suggest that cells may contain either GJB2 or GJB6 gene transcripts or both. This may be consistent with specialized GJ plaques having separate channel permeability and gating properties. A reduction in the number of GJB2 gene transcripts was found in the basal turn. Such information may be useful for future gene therapy.
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Chen P, Wu W, Zhang J, Chen J, Li Y, Sun L, Hou S, Yang J. Pathological mechanisms of connexin26-related hearing loss: Potassium recycling, ATP-calcium signaling, or energy supply? Front Mol Neurosci 2022; 15:976388. [PMID: 36187349 PMCID: PMC9520402 DOI: 10.3389/fnmol.2022.976388] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 08/11/2022] [Indexed: 11/17/2022] Open
Abstract
Hereditary deafness is one of the most common human birth defects. GJB2 gene mutation is the most genetic etiology. Gap junction protein 26 (connexin26, Cx26) encoded by the GJB2 gene, which is responsible for intercellular substance transfer and signal communication, plays a critical role in hearing acquisition and maintenance. The auditory character of different Connexin26 transgenic mice models can be classified into two types: profound congenital deafness and late-onset progressive hearing loss. Recent studies demonstrated that there are pathological changes including endocochlear potential reduction, active cochlear amplification impairment, cochlear developmental disorders, and so on, in connexin26 deficiency mice. Here, this review summarizes three main hypotheses to explain pathological mechanisms of connexin26-related hearing loss: potassium recycling disruption, adenosine-triphosphate-calcium signaling propagation disruption, and energy supply dysfunction. Elucidating pathological mechanisms underlying connexin26-related hearing loss can help develop new protective and therapeutic strategies for this common deafness. It is worthy of further study on the detailed cellular and molecular upstream mechanisms to modify connexin (channel) function.
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Affiliation(s)
- Penghui Chen
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong 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
| | - Wenjin Wu
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong 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
| | - Jifang Zhang
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong 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
| | - Junmin Chen
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong 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
| | - Yue Li
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong 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
| | - Lianhua Sun
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong 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
| | - Shule Hou
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong 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
- *Correspondence: Shule Hou,
| | - Jun Yang
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong 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
- Jun Yang,
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Jang MW, Lim J, Park MG, Lee JH, Lee CJ. Active role of glia-like supporting cells in the organ of Corti: Membrane proteins and their roles in hearing. Glia 2022; 70:1799-1825. [PMID: 35713516 DOI: 10.1002/glia.24229] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 05/23/2022] [Accepted: 05/30/2022] [Indexed: 12/13/2022]
Abstract
The organ of Corti, located in the cochlea in the inner ear, is one of the major sensory organs involved in hearing. The organ of Corti consists of hair cells, glia-like supporting cells, and the cochlear nerve, which work in harmony to receive sound from the outer ear and transmit auditory signals to the cochlear nucleus in the auditory ascending pathway. In this process, maintenance of the endocochlear potential, with a high potassium gradient and clearance of electrolytes and biochemicals in the inner ear, is critical for normal sound transduction. There is an emerging need for a thorough understanding of each cell type involved in this process to understand the sophisticated mechanisms of the organ of Corti. Hair cells have long been thought to be active, playing a primary role in the cochlea in actively detecting and transmitting signals. In contrast, supporting cells are thought to be silent and function to support hair cells. However, growing lines of evidence regarding the membrane proteins that mediate ionic movement in supporting cells have demonstrated that supporting cells are not silent, but actively play important roles in normal signal transduction. In this review, we summarize studies that characterize diverse membrane proteins according to the supporting cell subtypes involved in cochlear physiology and hearing. This review contributes to a better understanding of supporting cell functions and facilitates the development of potential therapeutic tools for hearing loss.
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Affiliation(s)
- Minwoo Wendy Jang
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Jiwoon Lim
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea.,IBS School, University of Science and Technology (UST), Daejeon, Republic of Korea
| | - Mingu Gordon Park
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Jae-Hun Lee
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - C Justin Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea.,IBS School, University of Science and Technology (UST), Daejeon, Republic of Korea
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10
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Zhang L, Wang W, Kim SM, Wang J, Zhou B, Kong W, Zheng J, Lin X. Virally Mediated Connexin 26 Expression in Postnatal Scala Media Significantly and Transiently Preserves Hearing in Connexin 30 Null Mice. Front Cell Dev Biol 2022; 10:900416. [PMID: 35573684 PMCID: PMC9091169 DOI: 10.3389/fcell.2022.900416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 04/11/2022] [Indexed: 11/24/2022] Open
Abstract
Non-sensory cells in the sensory epithelium of the cochlea are connected extensively by gap junctions. Functionally null mutations in GJB6 (encoding Cx30) cause hearing loss in humans. In this study, we injected AAV1-CB7-Gjb2 into the scala media between P0-2 in the cochlea of Gjb6−/− mice. The injection increased Cx26 expression and significantly preserved auditory functions. However, the hearing preservation gradually declined and essentially disappeared 3 months after the injections. In contrast, the morphological preservation was still significant at 3 months post-injection. We found that the expression of Cx26, at both the mRNA and protein levels, showed substantial decreases during the 3-month period. Curiously, treatments by injecting AAV1-CB7-Gjb6 with the identical approach failed to yield any hearing preservation. Our results demonstrated the first successful cochlear gene therapy treatment in mouse models by virally expressing a companion gene of Gjb6.
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Affiliation(s)
- Li Zhang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Wenwen Wang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Sun Myoung Kim
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Jianjun Wang
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Binfei Zhou
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Weijia Kong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - James Zheng
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Xi Lin
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
- *Correspondence: Xi Lin,
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11
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Waissbluth S, Maass JC, Sanchez HA, Martínez AD. Supporting Cells and Their Potential Roles in Cisplatin-Induced Ototoxicity. Front Neurosci 2022; 16:867034. [PMID: 35573297 PMCID: PMC9104564 DOI: 10.3389/fnins.2022.867034] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 04/06/2022] [Indexed: 11/13/2022] Open
Abstract
Cisplatin is a known ototoxic chemotherapy drug, causing irreversible hearing loss. Evidence has shown that cisplatin causes inner ear damage as a result of adduct formation, a proinflammatory environment and the generation of reactive oxygen species within the inner ear. The main cochlear targets for cisplatin are commonly known to be the outer hair cells, the stria vascularis and the spiral ganglion neurons. Further evidence has shown that certain transporters can mediate cisplatin influx into the inner ear cells including organic cation transporter 2 (OCT2) and the copper transporter Ctr1. However, the expression profiles for these transporters within inner ear cells are not consistent in the literature, and expression of OCT2 and Ctr1 has also been observed in supporting cells. Organ of Corti supporting cells are essential for hair cell activity and survival. Special interest has been devoted to gap junction expression by these cells as certain mutations have been linked to hearing loss. Interestingly, cisplatin appears to affect connexin expression in the inner ear. While investigations regarding cisplatin-induced hearing loss have been focused mainly on the known targets previously mentioned, the role of supporting cells for cisplatin-induced ototoxicity has been overlooked. In this mini review, we discuss the implications of supporting cells expressing OCT2 and Ctr1 as well as the potential role of gap junctions in cisplatin-induced cytotoxicity.
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Affiliation(s)
- Sofia Waissbluth
- Department of Otolaryngology, Pontificia Universidad Católica de Chile, Santiago, Chile
- *Correspondence: Sofia Waissbluth, ;
| | - Juan Cristóbal Maass
- Department of Otolaryngology, Hospital Clínico de la Universidad de Chile, Santiago, Chile
| | - Helmuth A. Sanchez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Instituto de Neurociencia, Universidad de Valparaíso, Valparaíso, Chile
| | - Agustín D. Martínez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Instituto de Neurociencia, Universidad de Valparaíso, Valparaíso, Chile
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12
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Liu XZ, Jin Y, Chen S, Xu K, Xie L, Qiu Y, Wang XH, Sun Y, Kong WJ. F-Actin Dysplasia Involved in Organ of Corti Deformity in Gjb2 Knockdown Mouse Model. Front Mol Neurosci 2022; 14:808553. [PMID: 35345836 PMCID: PMC8957075 DOI: 10.3389/fnmol.2021.808553] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 12/13/2021] [Indexed: 11/13/2022] Open
Abstract
Mutations in the GJB2 gene encoding connexin26 (Cx26) protein are one of the most common causes of hereditary deafness. Previous studies have found that different Cx26-null mouse models have severe hearing loss and deformity of the organ of Corti (OC) as well as a reduction in microtubules in pillar cells (PCs). To explore the underlying mechanism of OC deformity caused by Cx26 downregulation further, we established Cx26 knockdown (KD) mouse models at postnatal days (P)0 and P8. The actin filaments contained in the pillar cells of mice in the P0 KD group were reduced by 54.85% and vinculin was increased by 22%, while the outer hair cells (OHCs) showed normal F-actin content. In the P8 KD group, PCs and OHCs of mice also showed almost normal F-actin content. The G-actin/F-actin ratio increased by 38% in the P0 KD group. No significant change was found in the mRNA or protein expression level of G-actin or the cadherin–catenin core complex in the P0 KD group at P6. Moreover, immunofluorescence showed that the intensity of LRRK2 was reduced by 97% in the P0 KD group at P6. Our results indicate that Cx26 is involved in the maturation of the cytoskeleton during the development of the OC at the early postnatal stage. The polymerization of G-actin into F-actin is prevented in Cx26 KD mice.
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Affiliation(s)
- Xiao-zhou Liu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yuan Jin
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Sen Chen
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Kai Xu
- Department of Otolaryngology, Head and Neck Surgery, The Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Le Xie
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yue Qiu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiao-hui Wang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- *Correspondence: Yu Sun Wei-jia Kong
| | - Wei-jia Kong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- *Correspondence: Yu Sun Wei-jia Kong
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13
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Campbell KCM, Cosenza N, Meech R, Buhnerkempe M, Qin J, Rybak L, Fox DJ. D-methionine immediate and continued rescue after noise exposure does not prevent temporary threshold shift but alters cochlear and serum antioxidant levels. Int J Audiol 2021; 61:769-777. [PMID: 34369249 DOI: 10.1080/14992027.2021.1959659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVE Determine if D-methionine (D-met) rescue prevents temporary threshold shift (TTS) from steady-state or impulse noise and determine D-met's impact on serum and cochlear antioxidant levels. DESIGN D-met at 50, 100 or 200 mg/kg/doses were administered 0, 6 and 18 hours-post noise. ABRs at baseline and 24 hours post-noise measured TTS. Serum (SOD, CAT, GR, GPx) and cochlear (GSH, GSSG) antioxidant levels measured physiological influence. Three control groups, with impulse or steady-state or without noise, were saline-injected. STUDY SAMPLE Ten Chinchillas/group. RESULTS D-met rescue did not significantly reduce TTS or impact serum CAT, SOD, GPx or GR levels vs. noise-exposed control groups, but TTS was greater in all groups relative to no-noise controls. D-met significantly elevated CAT at 50 mg/kg vs. steady-state controls and SOD at 200 mg/kg vs. impulse noise controls. D-met significantly reduced cochlear GSH/GSSG ratios in the 100 mg/kg D-met group vs. impulse noise controls. CONCLUSIONS While D-met rescue has reduced permanent threshold shift in previous studies, it did not reduce TTS in this study. However, D-met rescue did alter selective serum and cochlear oxidative state changes 24 hours post-noise relative to controls. Results demonstrate TTS studies do not always predict PTS protection in otoprotectant experimental designs.
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Affiliation(s)
- Kathleen C M Campbell
- Department of Medical Microbiology, Immunology, and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Nicole Cosenza
- Department of Medical Microbiology, Immunology, and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Robert Meech
- Department of Medical Microbiology, Immunology, and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Michael Buhnerkempe
- Department of Internal Medicine, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Jun Qin
- Department of Computer and Electrical Engineering, Southern Illinois University Carbondale, Carbondale, IL, USA
| | - Leonard Rybak
- Department of Otolaryngology, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Daniel J Fox
- Department of Clinical Research, Springfield Clinic, Springfield, IL, USA
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14
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Hosoya M, Fujioka M, Murayama AY, Ogawa K, Okano H, Ozawa H. Dynamic Spatiotemporal Expression Changes in Connexins of the Developing Primate's Cochlea. Genes (Basel) 2021; 12:genes12071082. [PMID: 34356098 PMCID: PMC8307058 DOI: 10.3390/genes12071082] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 07/14/2021] [Accepted: 07/15/2021] [Indexed: 01/03/2023] Open
Abstract
Connexins are gap junction components that are essential for acquiring normal hearing ability. Up to 50% of congenital, autosomal-recessive, non-syndromic deafness can be attributed to variants in GJB2, the gene that encodes connexin 26. Gene therapies modifying the expression of connexins are a feasible treatment option for some patients with genetic hearing losses. However, the expression patterns of these proteins in the human fetus are not fully understood due to ethical concerns. Recently, the common marmoset was used as a primate animal model for the human fetus. In this study, we examined the expression patterns of connexin 26 and connexin 30 in the developing cochlea of this primate. Primate-specific spatiotemporal expression changes were revealed, which suggest the existence of primate-specific control of connexin expression patterns and specific functions of these gap junction proteins. Moreover, our results indicate that treatments for connexin-related hearing loss established in rodent models may not be appropriate for human patients, underscoring the importance of testing these treatments in primate models before applying them in human clinical trials.
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Affiliation(s)
- Makoto Hosoya
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, 35 Shinanomachi Shinjuku-ku, Tokyo 160-8582, Japan; (M.H.); (K.O.); (H.O.)
| | - Masato Fujioka
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, 35 Shinanomachi Shinjuku-ku, Tokyo 160-8582, Japan; (M.H.); (K.O.); (H.O.)
- Correspondence: ; Tel.: +81-3-5363-3827
| | - Ayako Y. Murayama
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi Shinjuku-ku, Tokyo 160-8582, Japan; (A.Y.M.); (H.O.)
- Laboratory for Marmoset Neural Architecture, RIKEN Center for Brain Science, Wako 351-0198, Japan
| | - Kaoru Ogawa
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, 35 Shinanomachi Shinjuku-ku, Tokyo 160-8582, Japan; (M.H.); (K.O.); (H.O.)
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi Shinjuku-ku, Tokyo 160-8582, Japan; (A.Y.M.); (H.O.)
- Laboratory for Marmoset Neural Architecture, RIKEN Center for Brain Science, Wako 351-0198, Japan
| | - Hiroyuki Ozawa
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, 35 Shinanomachi Shinjuku-ku, Tokyo 160-8582, Japan; (M.H.); (K.O.); (H.O.)
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15
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Defourny J, Audouard C, Davy A, Thiry M. Efnb2 haploinsufficiency induces early gap junction plaque disassembly and endocytosis in the cochlea. Brain Res Bull 2021; 174:153-160. [PMID: 34139316 DOI: 10.1016/j.brainresbull.2021.06.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 06/07/2021] [Accepted: 06/11/2021] [Indexed: 11/15/2022]
Abstract
Chromosome 13q deletions encompassing EFNB2, which encodes the transmembrane protein ephrin-B2, are likely to cause syndromic forms of sensorineural hearing loss of unclear origin. Thus, unravelling the pathogenic mechanisms could help to improve therapeutic strategies. In the cochlea, adjacent non-sensory epithelial cells are connected via gap junction channels, the activity of which is critical to maintain cochlear homeostasis. Here we show that ephrin-B2 promotes the assembly of connexin 30 (Cx30) gap junction plaques (GJPs) between adjacent non-sensory Deiters' cells. An in situ proximity ligation assay revealed that ephrin-B2 preferentially interacts with Cx30 in the periphery of the GJPs, i.e. where newly synthesized connexin hemichannels accrue to the GJP. Moreover, we observed that heterozygous mice encoding an Efnb2 null allele display excessive clathrin-mediated internalization of Cx30 GJPs in early postnatal stages. Finally, an in vitro organotypic assay revealed that ectopic activation of ephrin-B2 reverse signalling promotes the internalization of Cx30 GJPs. These data argue in favor of a cell-autonomous, Eph receptor-independent role of ephrin-B2 in the assembly of Cx30 GJPs. According to recent observations, early GJP degradation could certainly play a role in the pathogenic process leading to progressive sensorineural hearing loss due to Efnb2/EFNB2 haploinsufficiency.
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Affiliation(s)
- Jean Defourny
- GIGA-Neurosciences, Unit of Cell and Tissue Biology, University of Liège, CHU B36, 4000, Liège, Belgium.
| | - Christophe Audouard
- Center for Developmental Biology, Center for Integrative Biology, University of Toulouse, CNRS, UPS, 118 route de Narbonne, 31062, Toulouse, France
| | - Alice Davy
- Center for Developmental Biology, Center for Integrative Biology, University of Toulouse, CNRS, UPS, 118 route de Narbonne, 31062, Toulouse, France
| | - Marc Thiry
- GIGA-Neurosciences, Unit of Cell and Tissue Biology, University of Liège, CHU B36, 4000, Liège, Belgium
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16
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Fukunaga I, Oe Y, Danzaki K, Ohta S, Chen C, Shirai K, Kawano A, Ikeda K, Kamiya K. Modeling gap junction beta 2 gene-related deafness with human iPSC. Hum Mol Genet 2021; 30:1429-1442. [PMID: 33997905 DOI: 10.1093/hmg/ddab097] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 03/29/2021] [Accepted: 03/31/2021] [Indexed: 02/06/2023] Open
Abstract
There are >120 forms of non-syndromic deafness associated with identified genetic loci. In particular, mutation of the gap junction beta 2 gene (GJB2), which encodes connexin (CX)26 protein, is the most frequent cause of hereditary deafness worldwide. We previously described an induction method to develop functional CX26 gap junction-forming cells from mouse-induced pluripotent stem cells (iPSCs) and generated in vitro models for GJB2-related deafness. However, functional CX26 gap junction-forming cells derived from human iPSCs or embryonic stem cells (ESCs) have not yet been reported. In this study, we generated human iPSC-derived functional CX26 gap junction-forming cells (iCX26GJCs), which have the characteristics of cochlear supporting cells. These iCX26GJCs had gap junction plaque-like formations at cell-cell borders and co-expressed several markers that are expressed in cochlear supporting cells. Furthermore, we generated iCX26GJCs derived from iPSCs from two patients with the most common GJB2 mutation in Asia, and these cells reproduced the pathology of GJB2-related deafness. These in vitro models may be useful for establishing optimal therapies and drug screening for various mutations in GJB2-related deafness.
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Affiliation(s)
- Ichiro Fukunaga
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 1138421, Japan
| | - Yoko Oe
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 1138421, Japan
| | - Keiko Danzaki
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 1138421, Japan
| | - Sayaka Ohta
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 1138421, Japan
| | - Cheng Chen
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 1138421, Japan
| | - Kyoko Shirai
- Department of Otolaryngology, Head and Neck Surgery, Tokyo Medical University, Tokyo 1600023, Japan
| | - Atsushi Kawano
- Department of Otolaryngology, Head and Neck Surgery, Tokyo Medical University, Tokyo 1600023, Japan
| | - Katsuhisa Ikeda
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 1138421, Japan
| | - Kazusaku Kamiya
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 1138421, Japan
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17
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Fukunaga I, Oe Y, Chen C, Danzaki K, Ohta S, Koike A, Ikeda K, Kamiya K. Activin/Nodal/TGF-β Pathway Inhibitor Accelerates BMP4-Induced Cochlear Gap Junction Formation During in vitro Differentiation of Embryonic Stem Cells. Front Cell Dev Biol 2021; 9:602197. [PMID: 33968919 PMCID: PMC8097046 DOI: 10.3389/fcell.2021.602197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 03/30/2021] [Indexed: 11/13/2022] Open
Abstract
Mutations in gap junction beta-2 (GJB2), the gene that encodes connexin 26 (CX26), are the most frequent cause of hereditary deafness worldwide. We recently developed an in vitro model of GJB2-related deafness (induced CX26 gap junction-forming cells; iCX26GJCs) from mouse induced pluripotent stem cells (iPSCs) by using Bone morphogenetic protein 4 (BMP4) signaling-based floating cultures (serum-free culture of embryoid body-like aggregates with quick aggregation cultures; hereafter, SFEBq cultures) and adherent cultures. However, to use these cells as a disease model platform for high-throughput drug screening or regenerative therapy, cell yields must be substantially increased. In addition to BMP4, other factors may also induce CX26 gap junction formation. In the SFEBq cultures, the combination of BMP4 and the Activin/Nodal/TGF-β pathway inhibitor SB431542 (SB) resulted in greater production of isolatable CX26-expressing cell mass (CX26+ vesicles) and higher Gjb2 mRNA levels than BMP4 treatment alone, suggesting that SB may promote BMP4-mediated production of CX26+ vesicles in a dose-dependent manner, thereby increasing the yield of highly purified iCX26GJCs. This is the first study to demonstrate that SB accelerates BMP4-induced iCX26GJC differentiation during stem cell floating culture. By controlling the concentration of SB supplementation in combination with CX26+ vesicle purification, large-scale production of highly purified iCX26GJCs suitable for high-throughput drug screening or regenerative therapy for GJB2-related deafness may be possible.
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Affiliation(s)
| | | | | | | | | | | | | | - Kazusaku Kamiya
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo, Japan
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18
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Wang J, Song Q. Inhibition of connexin 43 induces hearing loss in postnatal mice. Physiol Int 2021. [PMID: 33769954 DOI: 10.1556/2060.2021.00008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/09/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND Connexin 43 (Cx43) is the most ubiquitously expressed member of the family of connexins, constituting gap junctions and mediating cell communication, still its role in hearing loss has been little studied. METHODS Immunohistochemistry was used to detect the expression pattern of Cx43. Spiral ganglia neurons (SGNs) and Corti co-culture were utilized to assay the re-innervation of hair cells by newborn SGNs. Gap19 was utilized to inhibit Cx43 hemichannels. Auditory brainstem responses (ABR) and endocochlear potential (E.P.) were measured to confirm the hearing loss. RESULTS The expression of Cx43 in P14 mice was higher than in P0 and P28 (adult) mice, the earlier time point coinciding with the early inner ear development. Additionally, the growth and synapse generation of fibers were inhibited after Gap 19 treatment of the co-cultures of the Corti and SGNs from newborn mice. Furthermore, the inhibition of Cx43 could increase the ABR threshold and decrease E.P. level in postnatal mice, whereas such an effect was not observed in adult mice. CONCLUSION The function of Cx43 is critical during the early development of mouse cochlea but is dispensable in adult mice.
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Affiliation(s)
- J Wang
- Department of Otolaryngology, Weifang City Hanting District People's Hospital, Weifang 261100, Shandong, China
| | - Q Song
- Department of Otolaryngology, Weifang City Hanting District People's Hospital, Weifang 261100, Shandong, China
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19
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Wang H, Gao Y, Guan J, Lan L, Yang J, Xiong W, Zhao C, Xie L, Yu L, Wang D, Wang Q. Phenotypic Heterogeneity of Post-lingual and/or Milder Hearing Loss for the Patients With the GJB2 c.235delC Homozygous Mutation. Front Cell Dev Biol 2021; 9:647240. [PMID: 33718389 PMCID: PMC7953049 DOI: 10.3389/fcell.2021.647240] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 02/08/2021] [Indexed: 01/01/2023] Open
Abstract
Objective To report the phenotypic heterogeneity of GJB2 c.235delC homozygotes associated with post-lingual and/or milder hearing loss, and explore the possible mechanism of these unconditional phenotypes. Methods Mutation screening of GJB2 was performed on all ascertained members from Family 1006983 and three sporadic patients by polymerase chain reaction (PCR) amplification and Sanger sequencing. Next generation sequencing (NGS) was successively performed on some of the affected members and normal controls from Family 1006983 to explore additional possible genetic codes. Reverse transcriptase–quantitative PCR was conducted to test the expression of Connexin30. Results We identified a Chinese autosomal recessive hearing loss family with the GJB2 c.235delC homozygous mutation, affected members from which had post-lingual moderate to profound hearing impairment, and three sporadic patients with post-lingual moderate hearing impairment, instead of congenital profound hearing loss. NGS showed no other particular variants. Overexpression of Connexin30 in some of these cases was verified. Conclusion Post-lingual and/or moderate hearing impairment phenotypes of GJB2 c.235delC homozygotes are not the most common phenotype, revealing the heterogeneity of GJB2 pathogenic mutations. To determine the possible mechanism that rescues part of the hearing or postpones onset age of these cases, more cases are required to confirm both Connexin30 overexpression and the existence of modifier genes.
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Affiliation(s)
- Hongyang Wang
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China
| | - Yun Gao
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Jing Guan
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Lan Lan
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Ju Yang
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Wenping Xiong
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Cui Zhao
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Linyi Xie
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Lan Yu
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Dayong Wang
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
| | - Qiuju Wang
- College of Otolaryngology, Head and Neck Surgery, Chinese People's Liberation Army (PLA) Institute of Otolaryngology, Chinese People's Liberation Army (PLA) General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Impairment Science of Ministry of Education, Beijing, China.,Key Lab of Hearing Impairment Prevention and Treatment of Beijing, Beijing, China
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20
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Naulin PA, Lozano B, Fuentes C, Liu Y, Schmidt C, Contreras JE, Barrera NP. Polydisperse molecular architecture of connexin 26/30 heteromeric hemichannels revealed by atomic force microscopy imaging. J Biol Chem 2020; 295:16499-16509. [PMID: 32887797 PMCID: PMC7864052 DOI: 10.1074/jbc.ra119.012128] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 08/31/2020] [Indexed: 11/06/2022] Open
Abstract
Connexin (Cx) protein forms hemichannels and gap junctional channels, which play diverse and profound roles in human physiology and diseases. Gap junctions are arrays of intercellular channels formed by the docking of two hemichannels from adjacent cells. Each hexameric hemichannel contains the same or different Cx isoform. Although homomeric Cxs forms have been largely described functionally and structurally, the stoichiometry and arrangement of heteromeric Cx channels remain unknown. The latter, however, are widely expressed in human tissues and variation might have important implications on channel function. Investigating properties of heteromeric Cx channels is challenging considering the high number of potential subunit arrangements and stoichiometries, even when only combining two Cx isoforms. To tackle this problem, we engineered an HA tag onto Cx26 or Cx30 subunits and imaged hemichannels that were liganded by Fab-epitope antibody fragments via atomic force microscopy. For Cx26-HA/Cx30 or Cx30-HA/Cx26 heteromeric channels, the Fab-HA binding distribution was binomial with a maximum of three Fab-HA bound. Furthermore, imaged Cx26/Cx30-HA triple liganded by Fab-HA showed multiple arrangements that can be derived from the law of total probabilities. Atomic force microscopy imaging of ringlike structures of Cx26/Cx30-HA hemichannels confirmed these findings and also detected a polydisperse distribution of stoichiometries. Our results indicate a dominant subunit stoichiometry of 3Cx26:3Cx30 with the most abundant subunit arrangement of Cx26-Cx26-Cx30-Cx26-Cx30-Cx30. To our knowledge, this is the first time that the molecular architecture of heteromeric Cx channels has been revealed, thus providing the basis to explore the functional effect of these channels in biology.
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Affiliation(s)
- Pamela A Naulin
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Benjamin Lozano
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Christian Fuentes
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Yu Liu
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Carla Schmidt
- Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Jorge E Contreras
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Nelson P Barrera
- Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile.
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21
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Defourny J, Thiry M. Tricellular adherens junctions provide a cell surface delivery platform for connexin 26/30 oligomers in the cochlea. Hear Res 2020; 400:108137. [PMID: 33291008 DOI: 10.1016/j.heares.2020.108137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 11/12/2020] [Accepted: 11/25/2020] [Indexed: 12/13/2022]
Abstract
In the cochlea, connexins 26 (Cx26) and 30 (Cx30) largely co-assemble into heteromeric gap junctions, which connect adjacent non-sensory epithelial cells. These channels are believed to ensure the rapid removal of K+ away from the base of sensory hair cells, resulting in K+ recycling back to the endolymph to maintain cochlear homeostasis. Many of the mutations in GJB2 and GJB6, which encode CX26 and CX30, impair the formation of membrane channels and cause autosomal hearing loss in humans. Although recent advances have been made, several important questions remain about connexin trafficking and gap junction biogenesis. Here we show that tricellular adherens junctions present at the crossroad between adjacent gap junction plaques, provide an unexpected cell surface delivery platform for Cx26/Cx30 oligomers. Using an in situ proximity ligation assay, we detected the presence of non-junctional Cx26/Cx30 oligomers within lipid raft-enriched tricellular junction sites. In addition, we observed that cadherin homophilic interactions are critically involved in microtubule-mediated trafficking of Cx26/Cx30 oligomers to the cell surface. Overall, our results unveil an unexpected role for tricellular junctions in the trafficking and assembly of membrane channels.
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Affiliation(s)
- Jean Defourny
- GIGA-Neurosciences, Unit of Cell and Tissue Biology, University of Liège, C.H.U B36, B-4000 Liège, Belgium.
| | - Marc Thiry
- GIGA-Neurosciences, Unit of Cell and Tissue Biology, University of Liège, C.H.U B36, B-4000 Liège, Belgium
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22
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Jovanovic S, Milenkovic I. Purinergic Modulation of Activity in the Developing Auditory Pathway. Neurosci Bull 2020; 36:1285-1298. [PMID: 33040238 DOI: 10.1007/s12264-020-00586-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 09/10/2020] [Indexed: 12/11/2022] Open
Abstract
Purinergic P2 receptors, activated by endogenous ATP, are prominently expressed on neuronal and non-neuronal cells during development of the auditory periphery and central auditory neurons. In the mature cochlea, extracellular ATP contributes to ion homeostasis, and has a protective function against noise exposure. Here, we focus on the modulation of activity by extracellular ATP during early postnatal development of the lower auditory pathway. In mammals, spontaneous patterned activity is conveyed along afferent auditory pathways before the onset of acoustically evoked signal processing. During this critical developmental period, inner hair cells fire bursts of action potentials that are believed to provide a developmental code for synaptic maturation and refinement of auditory circuits, thereby establishing a precise tonotopic organization. Endogenous ATP-release triggers such patterned activity by raising the extracellular K+ concentration and contributes to firing by increasing the excitability of auditory nerve fibers, spiral ganglion neurons, and specific neuron types within the auditory brainstem, through the activation of diverse P2 receptors. We review recent studies that provide new models on the contribution of purinergic signaling to early development of the afferent auditory pathway. Further, we discuss potential future directions of purinergic research in the auditory system.
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Affiliation(s)
- Sasa Jovanovic
- School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26129, Oldenburg, Germany
| | - Ivan Milenkovic
- School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26129, Oldenburg, Germany.
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23
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Albuloushi A, Lovgren ML, Steel A, Yeoh Y, Waters A, Zamiri M, Martin PE. A heterozygous mutation in GJB2 (Cx26F142L) associated with deafness and recurrent skin rashes results in connexin assembly deficiencies. Exp Dermatol 2020; 29:970-979. [PMID: 32866991 DOI: 10.1111/exd.14187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 08/11/2020] [Accepted: 08/26/2020] [Indexed: 12/12/2022]
Abstract
Mutations in GJB2 encoding Connexin 26 (CX26) are associated with hearing loss and hyperproliferative skin disorders of differing severity including keratitis-ichthyosis-deafness (KID) and Vohwinkel syndrome. A 6-year-old Caucasian girl who presented with recurrent skin rashes and sensorineural hearing loss harboured a heterozygous point mutation in GJB2 (c.424T > C; p.F142L). To characterize the impact of CX26F142L on cellular events. Plasmids CX26WT, CX26F142L, CX26G12R (KID) or CX26D66H (Vohwinkel) were transfected into HeLa cells expressing Cx26 or Cx43 or into HaCaT cells, a model keratinocyte cell line. Confocal microscopy determined protein localization. MTT assays assessed cell viability in the presence or absence of carbenoxolone, a connexin-channel blocker. Co-immunoprecipitation/Western blot analysis determined Cx43:Cx26 interactions. Quantitative real-time polymerase chain reaction assessed changes in gene expression of ER stress markers. Dye uptake assays determined Connexin-channel functionality. F142L and G12R were restricted to perinuclear areas. Collapse of the microtubule network, rescued by co-treatment with paclitaxel, occurred. ER stress was not involved. Cell viability was reduced in cells expressing F142L and G12R but not D66H. Unlike G12R that forms "leaky" hemichannels, F142L had restricted permeability. Cell viability of F142L and G12R transfected cells was greater in HeLa cells expressing Cx43 than in native Cx-free HeLa cells. Co-immunoprecipitation suggested a possible interaction between Cx43 and the three mutations. Expression of CX26F142L and G12R results in microtubule collapse, rescued by interaction with Cx43. The GJB2 mutations interacted with Cx43 suggesting that unique Cx43:Cx26 channels are central to the diverse phenotype of CX26 skin-related channelopathies.
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Affiliation(s)
- Ahmad Albuloushi
- Department of Biological and Biomedical Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK
| | - Marie-Louise Lovgren
- Department of Dermatology, University Hospital Crosshouse, Kilmarnock, UK.,Department of Dermatology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Ainsley Steel
- Department of Biological and Biomedical Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK
| | - Yeelon Yeoh
- Department of Biological and Biomedical Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK
| | - Alex Waters
- Department of Dermatology, University Hospital Crosshouse, Kilmarnock, UK
| | - Mozheh Zamiri
- Department of Dermatology, University Hospital Crosshouse, Kilmarnock, UK.,Department of Dermatology, Queen Elizabeth University Hospital, Glasgow, UK
| | - Patricia E Martin
- Department of Biological and Biomedical Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, UK
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24
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Askew C, Chien WW. Adeno-associated virus gene replacement for recessive inner ear dysfunction: Progress and challenges. Hear Res 2020; 394:107947. [PMID: 32247629 PMCID: PMC7939749 DOI: 10.1016/j.heares.2020.107947] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 03/02/2020] [Accepted: 03/04/2020] [Indexed: 01/08/2023]
Abstract
Approximately 3 in 1000 children in the US under 4 years of age are affected by hearing loss. Currently, cochlear implants represent the only line of treatment for patients with severe to profound hearing loss, and there are no targeted drug or biological based therapies available. Gene replacement is a promising therapeutic approach for hereditary hearing loss, where viral vectors are used to deliver functional cDNA to "replace" defective genes in dysfunctional cells in the inner ear. Proof-of-concept studies have successfully used this approach to improve auditory function in mouse models of hereditary hearing loss, and human clinical trials are on the immediate horizon. The success of this method is ultimately determined by the underlying biology of the defective gene and design of the treatment strategy, relying on intervention before degeneration of the sensory structures occurs. A challenge will be the delivery of a corrective gene to the proper target within the therapeutic window of opportunity, which may be unique for each specific defective gene. Although rescue of pre-lingual forms of recessive deafness have been explored in animal models thus far, future identification of genes with post-lingual onset that are amenable to gene replacement holds even greater promise for treatment, since the therapeutic window is likely open for a much longer period of time. This review summarizes the current state of adeno-associated virus (AAV) gene replacement therapy for recessive hereditary hearing loss and discusses potential challenges and opportunities for translating inner ear gene replacement therapy for patients with hereditary hearing loss.
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Affiliation(s)
- Charles Askew
- Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Wade W Chien
- Inner Ear Gene Therapy Program, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health, Bethesda, MD, USA; Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, MD, USA.
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25
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Zhang L, Wu X, Lin X. Gene therapy for genetic mutations affecting non-sensory cells in the cochlea. Hear Res 2020; 394:107858. [PMID: 31791650 DOI: 10.1016/j.heares.2019.107858] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/13/2019] [Accepted: 11/22/2019] [Indexed: 01/15/2023]
Abstract
Congenital hearing loss (HL) affects about 1 in every 500 infants. Among those affected more than half are caused by genetic mutations. According to the cellular sites affected by mutations in the cochlea, deafness genes could be classified into three major groups: those affecting the function of hair cells and synapses, cochlear supporting cells, and cells in the stria vascularis (SV) as well as in the lateral wall. The second and third groups account for more than half of all sensorineural hearing loss (SNHL) cases caused by genetic mutations. Current major treatment options for SNHL patients are hearing aids and cochlear implants (CIs). Hearing aids can only help patients with moderate to severe HL. Resolution of CIs is still improving and these devices are quite expensive especially when lifetime rehabilitation and maintenance costs are included. Tremendous efforts have been made to find novel treatments that are expected to restore hearing with higher-resolution and more natural quality, and to have a significantly lower cost over the lifetime of uses. Gene therapy studies have made impressive progresses in preclinical trials. This review focuses on deafness genes that affect supporting cells and cells in the SV of the cochlea. We will discuss recent progresses and remaining challenges for gene therapies targeting mutations in deafness genes belonging to this category.
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Affiliation(s)
- Li Zhang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China; Department of Otolaryngology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322-3030, USA
| | - Xuewen Wu
- Department of Otolaryngology Head and Neck Surgery, Xiangya Hospital of Central South University, 87 Xiangya Road, Changsha, Hunan, 410008, China; Department of Otolaryngology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322-3030, USA
| | - Xi Lin
- Department of Otolaryngology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322-3030, USA.
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26
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Chen B, Xu H, Mi Y, Jiang W, Guo D, Zhang J, Zhao Y, Tang W. Mechanisms of hearing loss and cell death in the cochlea of connexin mutant mice. Am J Physiol Cell Physiol 2020; 319:C569-C578. [PMID: 32755449 DOI: 10.1152/ajpcell.00483.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mutations in connexin 30 (Cx30) are known to cause severe congenital hearing impairment; however, the mechanism by which Cx30 mediates homeostasis of endocochlear gap junctions is unclear. We used a gene deletion mouse model to explore the mechanisms of Cx30 in preventing hearing loss. Our results suggest that despite severe loss of the auditory brain-stem response and endocochlear potential at postnatal day 18, Cx30-/- mice only show sporadic loss of the outer hair cells. This inconsistency in the time course and severity of hearing and hair cell losses in Cx30-/- mice might be explained, in part, by an increase in reactive oxygen species generation beginning at postnatal day 10. The expression of oxidative stress genes was increased in Cx30-/- mice in the stria vascularis, spiral ligament, and organ of Corti. Furthermore, Cx30 deficiency caused mitochondrial dysfunction at postnatal day 18, as assessed by decreased ATP levels and decreased expression of mitochondrial complex I proteins, especially in the stria vascularis. Proteomic analysis further identified 444 proteins that were dysregulated in Cx30-/- mice, including several that are involved in mitochondria electron transport, ATP synthesis, or ion transport. Additionally, proapoptotic proteins, including Bax, Bad, and caspase-3, were upregulated at postnatal day 18, providing a molecular basis to explain the loss of hearing that occurs before hair cell loss. Therefore, our results are consistent with an environment of oxidative stress and mitochondrial damage in the cochlea of Cx30-/- mice that is coincident with hearing loss but precedes hair cell loss.
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Affiliation(s)
- Bei Chen
- Department of Otology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Hongen Xu
- Center for Precision Medicine of Zhengzhou University, Zhengzhou, China
| | - Yanfang Mi
- Department of Otolaryngology, the Second Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Wei Jiang
- Center for Precision Medicine of Zhengzhou University, Zhengzhou, China
| | - Dan Guo
- Department of Clinical Medicine, Henan Medical College, Zhengzhou, China
| | - Jinhui Zhang
- Department of Otology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Yulin Zhao
- Department of Otology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Wenxue Tang
- Center for Precision Medicine of Zhengzhou University, Zhengzhou, China.,Department of Otolaryngology, the Second Affiliated Hospital of Zhengzhou University, Zhengzhou, China
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27
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The Functional Role of CONNEXIN 26 Mutation in Nonsyndromic Hearing Loss, Demonstrated by Zebrafish Connexin 30.3 Homologue Model. Cells 2020; 9:cells9051291. [PMID: 32455934 PMCID: PMC7290585 DOI: 10.3390/cells9051291] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 05/20/2020] [Accepted: 05/20/2020] [Indexed: 01/02/2023] Open
Abstract
Nonsyndromic hearing loss (NSHL) is of great clinical importance, and mutations in the GJB2 gene and the encoded human CONNEXIN 26 (CX26) protein play important roles in the genetic pathogenesis. The CX26 p.R184Q mutation was shown to be a dominant-negative effect in our previous study. Previously, we also demonstrated that zebrafish Cx30.3 is orthologous to human CX26. In the present study, we established transgenic zebrafish models with mutated Cx30.3 specifically expressed in the supporting cells of zebrafish inner ears driven by the agr2 promoter, to demonstrate and understand the mechanism by which the human CX26 R.184 mutation causes NSHL. Our results indicated that significant structural changes in the inner ears of transgenic lines with mutations were measured and compared to wild-type zebrafish. Simultaneously, significant alterations of transgenic lines with mutations in swimming behavior were analyzed with the zebrafish behavioral assay. This is the first study to investigate the functional results of the CX26 p.R184Q mutation with in vivo disease models. Our work supports and confirms the pathogenic role of the CX26 p.R184Q mutation in NSHL, with a hypothesized mechanism of altered interaction among amino acids in the connexins.
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28
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Beach R, Abitbol JM, Allman BL, Esseltine JL, Shao Q, Laird DW. GJB2 Mutations Linked to Hearing Loss Exhibit Differential Trafficking and Functional Defects as Revealed in Cochlear-Relevant Cells. Front Cell Dev Biol 2020; 8:215. [PMID: 32300592 PMCID: PMC7142214 DOI: 10.3389/fcell.2020.00215] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 03/12/2020] [Indexed: 11/13/2022] Open
Abstract
GJB2 gene (that encodes Cx26) mutations are causal of hearing loss highlighting the importance of Cx26-based channel signaling amongst the supporting cells in the organ of Corti. While the majority of these GJB2 mutations are inherited in an autosomal recessive manner, others are inherited in an autosomal dominant manner and lead to syndromic hearing loss as well as skin diseases. To assess if common or divergent mechanisms are at the root of GJB2-linked hearing loss, we expressed several mutants in cochlear-relevant HEI-OC1 cells derived from the developing organ of Corti. Since supporting cells of the mature mammalian organ of Corti have negligible Cx43, but HEI-OC1 cells are rich in Cx43, we first used CRISPR-Cas9 to ablate endogenous Cx43, thus establishing a connexin-deficient platform for controlled reintroduction of hearing-relevant connexins and Cx26 mutants. We found three distinct outcomes and cellular phenotypes when hearing loss-linked Cx26 mutants were expressed in cochlear-relevant cells. The dominant syndromic Cx26 mutant N54K had trafficking defects and did not fully prevent wild-type Cx26 gap junction plaque formation but surprisingly formed gap junctions when co-expressed with Cx30. In contrast, the dominant syndromic S183F mutant formed gap junctions incapable of transferring dye and, as expected, co-localized in the same gap junctions as wild-type Cx26 and Cx30, but also gained the capacity to intermix with Cx43 within gap junctions. Both recessive non-syndromic Cx26 mutants (R32H and R184P) were retained in intracellular vesicles including early endosomes and did not co-localize with Cx30. As might be predicted, none of the Cx26 mutants prevented Cx43 gap junction plaque formation in Cx43-rich HEI-OC1 cells while Cx43-ablation had little effect on the expression of reference genes linked to auditory cell differentiation. We conclude from our studies in cochlear-relevant cells that the selected Cx26 mutants likely evoke hearing loss via three unique connexin defects that are independent of Cx43 status.
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Affiliation(s)
- Rianne Beach
- Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
| | - Julia M. Abitbol
- Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
| | - Brian L. Allman
- Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
| | - Jessica L. Esseltine
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Qing Shao
- Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
| | - Dale W. Laird
- Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
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29
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Falah M, Houshmand M, Balali M, Asghari A, Bagher Z, Alizadeh R, Farhadi M. Role of GJB2 and GJB6 in Iranian Nonsyndromic Hearing Impairment: From Molecular Analysis to Literature Reviews. Fetal Pediatr Pathol 2020; 39:1-12. [PMID: 31215297 DOI: 10.1080/15513815.2019.1627625] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Background: Hearing impairment (HI) is a heterogeneous disorder. GJB2 and GJB6 genes are typically the first line of genetic screening before proceeding to any massive parallel sequencing. We evaluated the clinical utility of GJB2 and GJB6 testing in the Iranian population. Methods: GJB2 and GJB6 were sequenced. PubMed and Google Scholar were searched for Iranian publications on deletions in the DFNB1 locus. Results: We detected mutations of GJB2 in 16.5%, and no mutations of GJB6. Literature review revealed no reports of mutations of GJB6 in the Iranian population. Conclusion: This data and literature reviews indicate that GJB6 is not commonly responsible for Iranian nonsyndromic HI. Hence, the clinical utility of GJB6 genetic analysis as a first line for HI evaluation does not have the same utility as GJB2. The study is consistent with recent studies emphasizing the role of ethnicity in the selection of HI genetic testing strategy.
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Affiliation(s)
- Masoumeh Falah
- ENT and Head & Neck Research Center and Department, The Five Senses Institute, Hazrat Rasool Akram Hospital, Iran University of Medical Sciences, Tehran, Islamic Republic of Iran
| | - Massoud Houshmand
- ENT and Head & Neck Research Center and Department, The Five Senses Institute, Hazrat Rasool Akram Hospital, Iran University of Medical Sciences, Tehran, Islamic Republic of Iran.,Department of Medical Genetics, National Institute for Genetic Engineering and Biotechnology, Tehran, Islamic Republic of Iran
| | - Maryam Balali
- ENT and Head & Neck Research Center and Department, The Five Senses Institute, Hazrat Rasool Akram Hospital, Iran University of Medical Sciences, Tehran, Islamic Republic of Iran
| | - Alimohamad Asghari
- Skull Base Research Center, Iran University of Medical Sciences, Tehran, Islamic Republic of Iran
| | - Zohreh Bagher
- ENT and Head & Neck Research Center and Department, The Five Senses Institute, Hazrat Rasool Akram Hospital, Iran University of Medical Sciences, Tehran, Islamic Republic of Iran
| | - Rafieh Alizadeh
- ENT and Head & Neck Research Center and Department, The Five Senses Institute, Hazrat Rasool Akram Hospital, Iran University of Medical Sciences, Tehran, Islamic Republic of Iran
| | - Mohammad Farhadi
- ENT and Head & Neck Research Center and Department, The Five Senses Institute, Hazrat Rasool Akram Hospital, Iran University of Medical Sciences, Tehran, Islamic Republic of Iran
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30
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31
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Wu X, Zhang W, Li Y, Lin X. Structure and Function of Cochlear Gap Junctions and Implications for the Translation of Cochlear Gene Therapies. Front Cell Neurosci 2019; 13:529. [PMID: 31827424 PMCID: PMC6892400 DOI: 10.3389/fncel.2019.00529] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 11/13/2019] [Indexed: 12/23/2022] Open
Abstract
Connexins (Cxs) are ubiquitous membrane proteins that are found throughout vertebrate organs, acting as building blocks of the gap junctions (GJs) known to play vital roles in the normal function of many organs. Mutations in Cx genes (particularly GJB2, which encodes Cx26) cause approximately half of all cases of congenital hearing loss in newborns. Great progress has been made in understanding GJ function and the molecular mechanisms for the role of Cxs in the cochlea. Data reveal that multiple types of Cxs work together to ensure normal development and function of the cochlea. These findings include many aspects not proposed in the classic K+ recycling theory, such as the formation of normal cochlear morphology (e.g., the opening of the tunnel of Corti), the fine-tuning of the innervation of nerve fibers to the hair cells (HCs), the maturation of the ribbon synapses, and the initiation of the endocochlear potential (EP). New data, especially those collected from targeted modification of major Cx genes in the mouse cochlea, have demonstrated that Cx26 plays an essential role in the postnatal maturation of the cochlea. Studies also show that Cx26 and Cx30 assume very different roles in the EP generation, given that only Cx26 is required for normal hearing. This article will review our current understanding of the molecular structure, cellular distribution, and major functions of cochlear GJs. Potential implications of the knowledge of cochlear GJs on the design and implementation of translational studies of cochlear gene therapies for Cx mutations are also discussed.
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Affiliation(s)
- Xuewen Wu
- Department of Otolaryngology, Head-Neck and Surgery, Xiangya Hospital of Central South University, Changsha, China
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
| | - Wenjuan Zhang
- Department of Otolaryngology, Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yihui Li
- Department of Pharmacy, Changsha Hospital of Traditional Medicine, Changsha, China
| | - Xi Lin
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
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32
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Fukunaga I, Fujimoto A, Hatakeyama K, Kurebayashi N, Ikeda K, Kamiya K. Generation of Functional CX26–Gap‐Junction‐Plaque‐Forming Cells with Spontaneous Ca
2+
Transients via a Gap Junction Characteristic of Developing Cochlea. ACTA ACUST UNITED AC 2019; 51:e100. [DOI: 10.1002/cpsc.100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Ichiro Fukunaga
- Department of OtorhinolaryngologyJuntendo University Faculty of Medicine Tokyo Japan
| | - Ayumi Fujimoto
- Department of OtorhinolaryngologyJuntendo University Faculty of Medicine Tokyo Japan
| | - Kaori Hatakeyama
- Department of OtorhinolaryngologyJuntendo University Faculty of Medicine Tokyo Japan
| | - Nagomi Kurebayashi
- Department of Cellular and Molecular PharmacologyJuntendo University Graduate School of Medicine Tokyo Japan
| | - Katsuhisa Ikeda
- Department of OtorhinolaryngologyJuntendo University Faculty of Medicine Tokyo Japan
| | - Kazusaku Kamiya
- Department of OtorhinolaryngologyJuntendo University Faculty of Medicine Tokyo Japan
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33
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Expression pattern of Connexin 26 and Connexin 30 in mature cochlea of the monkey. Biochem Biophys Res Commun 2019; 518:357-361. [PMID: 31421828 DOI: 10.1016/j.bbrc.2019.08.063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 08/11/2019] [Indexed: 10/26/2022]
Abstract
Connexin26 (Cx26) and Cx30 are the predominant connexin subtypes found in the cochlea. They play an essential role in the cochlear functions. However, most studies use mice and the data on the cochlear expression profiles of the two Cxs in higher animals (e.g., humans) are scarce. Studies using the cochleae from non-human primate other than mice may provide information needed to narrow this gap. Here we studied cellular distributions of Cx26 and Cx30 in the adult monkey and guinea pig cochleae by immunofluorescent labeling and confocal microscopy observations. We detected Cx26 and Cx30 expressions in the type I, II& V fibrocytes in the spiral ligament, fibrocytes of the spiral limbus, in the supporting cells of organ of Corti, inner and outer sulcus cells, and in the basal cells of the stria vascularis. Both Cx26 and Cx30 were not detected in hair cells, in mesenchymal cells under the basilar membrane and cells lining the scala vestibule. Cells of the Reissner's membrane and spiral ganglion neurons are also negative. These findings demonstrate that cochlear expressions of Cx26 and Cx30 in the adult mouse, guinea pig and non-human primate have a common cellular pattern.
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Lu X, Chen Z, Vick S, Watsky MA. Vitamin D receptor and metabolite effects on corneal epithelial cell gap junction proteins. Exp Eye Res 2019; 187:107776. [PMID: 31465769 DOI: 10.1016/j.exer.2019.107776] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/12/2019] [Accepted: 08/23/2019] [Indexed: 12/29/2022]
Abstract
Vitamin D is a fat-soluble prohormone that can be activated both systemically and within individual tissues. Our lab has previously demonstrated that the corneal epithelium can activate vitamin D and that the vitamin D metabolites 1,25(OH)2D3 and 24R,25(OH)2D3 can affect corneal epithelial migration, proliferation, and tight and gap junction function. These vitamin D-derived metabolites signal through the vitamin D receptor (VDR). The purpose of this study was to specifically determine the effects of 1,25(OH)2D3 and 24R,25(OH)2D3 on corneal epithelial cell gap junction proteins. Connexin (Cx) 26, 30 and 43 protein expression was detected in a human corneal epithelial cell line (HCEC), wild type and vitamin D receptor knockout (VDR-/-) mouse corneas, and cultured mouse primary epithelial cells (MPCEC). In vitro gap junction function was assessed using the scrape loading/dye transfer assay. HCEC and MPCEC were treated with 1,25(OH)2D3 or 24R,25(OH)2D3. Western blotting was used to detect gap junction proteins. Vitamin D3 effects on epithelial intracellular Ca++ (Ca++i) were determined using the dye Cal-520. Cx26 and Cx43 protein levels were significantly increased in HCEC and MPCEC treated with both 1,25(OH)2D3 and 24R,25(OH)2D3. Cx30 and Cx43 protein levels were also significantly increased in VDR-/- MPCEC. In vitro gap junction connectivity was significanlty enhanced in HCEC and MPCEC cultured with 24R,25(OH)2D3 and 1,25(OH)2D3. Ca++i was not affected by 1,25(OH)2D3 or 24R,25(OH)2D3 in HCEC or MPCEC. We conclude that both 1,25(OH)2D3 and 24R,25(OH)2D3 are positive regulators of connexin proteins and gap junction communication in the corneal epithelium. These vitamin D metabolites appear to signal through both VDR-dependent and -independent pathways. The effects of vitamin D on corneal epithelial gap junctions do not seem to be dependent on Ca++i.
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Affiliation(s)
- Xiaowen Lu
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Zhong Chen
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Sarah Vick
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Mitchell A Watsky
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA, USA; The Graduate School, Augusta University, Augusta, GA, USA.
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Mammano F. Inner Ear Connexin Channels: Roles in Development and Maintenance of Cochlear Function. Cold Spring Harb Perspect Med 2019; 9:a033233. [PMID: 30181354 PMCID: PMC6601451 DOI: 10.1101/cshperspect.a033233] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Connexin 26 and connexin 30 are the prevailing isoforms in the epithelial and connective tissue gap junction systems of the developing and mature cochlea. The most frequently encountered variants of the genes that encode these connexins, which are transcriptionally coregulated, determine complete loss of protein function and are the predominant cause of prelingual hereditary deafness. Reducing connexin 26 expression by Cre/loxP recombination in the inner ear of adult mice results in a decreased endocochlear potential, increased hearing thresholds, and loss of >90% of outer hair cells, indicating that this connexin is essential for maintenance of cochlear function. In the developing cochlea, connexins are necessary for intercellular calcium signaling activity. Ribbon synapses and basolateral membrane currents fail to mature in inner hair cells of mice that are born with reduced connexin expression, even though hair cells do not express any connexin. In contrast, pannexin 1, an alternative mediator of intercellular signaling, is dispensable for hearing acquisition and auditory function.
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Affiliation(s)
- Fabio Mammano
- University of Padova, Department of Physics and Astronomy "G. Galilei," Padova 35129, Italy
- CNR Institute of Cell Biology and Neurobiology, Monterotondo 00015, Italy
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China
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Nishiyama N, Yamaguchi T, Yoneyama M, Onaka Y, Ogita K. Disruption of Gap Junction-Mediated Intercellular Communication in the Spiral Ligament Causes Hearing and Outer Hair Cell Loss in the Cochlea of Mice. Biol Pharm Bull 2019; 42:73-80. [PMID: 30606991 DOI: 10.1248/bpb.b18-00559] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is well-known that outer hair cell (OHC) loss occurs in the cochlea of animal models of permanent hearing loss induced by intense noise exposure. Our earlier studies demonstrated the production of hydroxynonenal and peroxynitrite, as well as the disruption of gap junction-mediated intercellular communication (GJIC), in the cochlear spiral ligament prior to noise-induced sudden hearing loss. The goal of the present study was to evaluate the mechanism underlying cochlear OHC loss after sudden hearing loss induced by intense noise exposure. In organ of Corti explant cultures from mice, no significant OHC loss was observed after in vitro exposure to 4-hydroxynonenal (a product of lipid peroxidation), H2O2, SIN-1 (peroxynitrite generator), and carbenoxolone (a gap junction inhibitor). Interestingly, in vivo intracochlear carbenoxolone injection through the posterior semicircular canal caused marked OHC and hearing loss, as well as the disruption of gap junction-mediated intercellular communication in the cochlear spiral ligament. However, no significant OHC loss was observed in vivo in animals treated with 4-hydroxynonenal and SIN-1. Taken together, our data suggest that disruption of GJIC in the cochlear lateral wall structures is an important cause of cochlear OHC loss in models of hearing loss, including those induced by noise.
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Affiliation(s)
- Norito Nishiyama
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Setsunan University
| | - Taro Yamaguchi
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Setsunan University
| | - Masanori Yoneyama
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Setsunan University
| | - Yusuke Onaka
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Setsunan University
| | - Kiyokazu Ogita
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Setsunan University
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Defourny J, Thelen N, Thiry M. Actin-independent trafficking of cochlear connexin 26 to non-lipid raft gap junction plaques. Hear Res 2019; 374:69-75. [DOI: 10.1016/j.heares.2019.01.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 12/13/2018] [Accepted: 01/24/2019] [Indexed: 12/15/2022]
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Defourny J. Eph/ephrin signalling in the development and function of the mammalian cochlea. Dev Biol 2019; 449:35-40. [PMID: 30771305 DOI: 10.1016/j.ydbio.2019.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 02/10/2019] [Accepted: 02/11/2019] [Indexed: 12/12/2022]
Abstract
In mammals, the functional development of the cochlea requires the tight regulation of multiple molecules and signalling pathways including fibroblast growth factors, bone morphogenetic proteins, Wnt and Notch signalling pathways. Over the last decade, the Eph/ephrin system also emerged as a key player of the development and function of the mammalian cochlea. In this review, we discuss the recent advances on the role of Eph/ephrin signalling in patterning the cochlear sensory epithelium and the complex innervation of mechanosensory hair cells by spiral ganglion neurons. Finally, we address the issue of a syndromic form of hearing loss caused by a deficient member of the Eph/ephrin family.
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Affiliation(s)
- Jean Defourny
- GIGA-Neurosciences, Unit of Cell and Tissue Biology, University of Liège, C.H.U. B36, B-4000, Liège, Belgium.
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Cochlear connexin 30 homomeric and heteromeric channels exhibit distinct assembly mechanisms. Mech Dev 2019; 155:8-14. [DOI: 10.1016/j.mod.2018.10.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 10/04/2018] [Indexed: 01/01/2023]
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Kelly JJ, Abitbol JM, Hulme S, Press ER, Laird DW, Allman BL. The connexin 30 A88V mutant reduces cochlear gap junction expression and confers long-term protection against hearing loss. J Cell Sci 2019; 132:jcs.224097. [PMID: 30559251 DOI: 10.1242/jcs.224097] [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: 08/17/2018] [Accepted: 12/06/2018] [Indexed: 12/23/2022] Open
Abstract
Mutations in the genes that encode the gap junction proteins connexin 26 (Cx26, encoded by GJB2) and Cx30 (GJB6) are the leading cause of hereditary hearing loss. That said, the Cx30 p.Ala88Val (A88V) mutant causes Clouston syndrome, but not hearing loss. Here, we report that the Cx30-A88V mutant, despite being toxic to inner ear-derived HEI-OC1 cells, conferred remarkable long-term protection against age-related high frequency hearing loss in Cx30A88V/A88V mice. During early development, there were no overt structural differences in the cochlea between genotypes, including a normal complement of hair cells; however, the supporting cell Cx30 gap junction plaques in mutant mice were reduced in size. In adulthood, Cx30A88V/A88V mutant mice had a reduction of cochlear Cx30 mRNA and protein, yet a full complement of hair cells. Conversely, the age-related high frequency hearing loss in Cx30+/+ and Cx30+/A88V mice was due to extensive loss of outer hair cells. Our data suggest that the Cx30-A88V mutant confers long-term hearing protection and prevention of hair cell death, possibly via a feedback mechanism that leads to the reduction of total Cx30 gap junction expression in the cochlea.
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Affiliation(s)
- John J Kelly
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Julia M Abitbol
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Stephanie Hulme
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Eric R Press
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Dale W Laird
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Brian L Allman
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario N6A 5C1, Canada
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The spatial distribution pattern of Connexin26 expression in supporting cells and its role in outer hair cell survival. Cell Death Dis 2018; 9:1180. [PMID: 30518746 PMCID: PMC6281596 DOI: 10.1038/s41419-018-1238-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 11/01/2018] [Accepted: 11/20/2018] [Indexed: 01/17/2023]
Abstract
Mutations in the GJB2 gene (which encodes Connexin26 (Cx26)) account for about a quarter of all cases of non-syndromic deafness. Previous studies have indicated that knockout (KO) of Gjb2 gene during early postnatal days can cause outer hair cell (OHC) loss in mouse models. However, the postnatal spatial distribution pattern of Cx26 in different types of supporting cells (SCs) and the role of such distributions for the survival of OHCs is still obscure. In this study, the spatial distribution patterns of Cx26 in SCs were observed, and based on these observations different spatial Cx26-null mouse models were established in order to determine the effect of changes in the spatial distribution of Cx26 in SCs on the survival of OHCs. At postnatal day (P)3, unlike the synchronous expression of Cx26 along both longitudinal and radial boundaries of most types of SCs, Cx26 expression was primarily observed along the longitudinal boundaries of rows of Deiter’s cells (DCs). From P5 to P7, radial expression of Cx26 was gradually observed between adjacent rows of DCs. When Gjb2 gene was knocked out at random in different types of SCs, about 40% of the total DCs lost Cx26 expression and these Cx26-null DCs were distributed randomly in all three rows of DCs. The mice in this randomly Cx26-null group showed normal hearing and no significant OHC loss. When using a longitudinal KO pattern to induce knockout of Gjb2 gene specifically in the third row of DCs, about 33% of the total DCs lost Cx26 expression in this specific longitudinally Cx26-null group. The mice in this group showed late-onset hearing loss and significant OHC loss, however, the morphology of corresponding DCs was slightly altered. In both experimental groups, no substantial DC loss was observed. These results indicate that longitudinal Cx26-based channels are predominant in DCs during P3–P5. The Cx26 expression along rows of DCs might play a key role in the survival of OHCs, but this longitudinal KO pattern in DCs has a limited effect on DC survival or on its postnatal development.
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Delmar M, Laird DW, Naus CC, Nielsen MS, Verselis VK, White TW. Connexins and Disease. Cold Spring Harb Perspect Biol 2018; 10:cshperspect.a029348. [PMID: 28778872 DOI: 10.1101/cshperspect.a029348] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Inherited or acquired alterations in the structure and function of connexin proteins have long been associated with disease. In the present work, we review current knowledge on the role of connexins in diseases associated with the heart, nervous system, cochlea, and skin, as well as cancer and pleiotropic syndromes such as oculodentodigital dysplasia (ODDD). Although incomplete by virtue of space and the extent of the topic, this review emphasizes the fact that connexin function is not only associated with gap junction channel formation. As such, both canonical and noncanonical functions of connexins are fundamental components in the pathophysiology of multiple connexin related disorders, many of them highly debilitating and life threatening. Improved understanding of connexin biology has the potential to advance our understanding of mechanisms, diagnosis, and treatment of disease.
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Affiliation(s)
- Mario Delmar
- The Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York 10016
| | - Dale W Laird
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario N6A5C1, Canada
| | - Christian C Naus
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Morten S Nielsen
- Department of Biological Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Vytautas K Verselis
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, New York 10461
| | - Thomas W White
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York 11790
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Chen K, Wu X, Zong L, Jiang H. GJB3/GJB6 screening in GJB2 carriers with idiopathic hearing loss: Is it necessary? J Clin Lab Anal 2018; 32:e22592. [PMID: 29926981 DOI: 10.1002/jcla.22592] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Accepted: 05/29/2018] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Genetic analysis detected excessive mono-allelic recessive GJB2 mutations in individuals with idiopathic deafness; the remaining alleles in trans/cis are underdetermined. The aim of this study was to assess the contributions of variants in GJB3 or GJB6 to non-syndromic sensorineural hearing impairment (NSHI) in Chinese patients with mono-allelic GJB2 mutations. METHODS The entire coding sequences of GJB3/GJB6, as well as deletions in GJB6, in a cohort of NSHI patients (n = 100) carrying likely pathogenic heterozygous GJB2 mutations, were tested. Targeted next generation sequencing was further performed in a multiplex family GDHY with moderate to profound NSHI. RESULTS Putatively causative GJB3 variant underlied 1% (1/100) in this cohort. In family GDHY, we identified a rare GJB3 c.250G>A mutation, as double heterozygotes with GJB2 c.109G>A and/or a novel GJB2 mutation c.638T>C predicted to be damaging in a digenic inheritance after precluding other attributable mutations from 127 deafness genes. No GJB6 mutation was found. CONCLUSIONS GJB3/GJB6 variants account for a low proportion in autosomal recessive GJB2 mutation carriers in our cohort. Environmental causes, or other NSHI relevant genes, revealed by targeted next generation sequencing or whole exome sequencing, may play major roles in triggering deafness in these patients.
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Affiliation(s)
- Kaitian Chen
- Department of Otorhinolaryngology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.,Institute of Otorhinolaryngology, Sun Yat-sen University, Guangzhou, China
| | - Xuan Wu
- Department of Otorhinolaryngology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.,Institute of Otorhinolaryngology, Sun Yat-sen University, Guangzhou, China
| | - Ling Zong
- Department of Otorhinolaryngology, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Hongyan Jiang
- Department of Otorhinolaryngology, Hainan General Hospital, Haikou, China
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Amritkumar P, Jeffrey JM, Chandru J, Vanniya S P, Kalaimathi M, Ramakrishnan R, Karthikeyen NP, Srikumari Srisailapathy CR. Role of DFNB1 mutations in hereditary hearing loss among assortative mating hearing impaired families from South India. BMC MEDICAL GENETICS 2018; 19:105. [PMID: 29921236 PMCID: PMC6008914 DOI: 10.1186/s12881-018-0609-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 05/18/2018] [Indexed: 08/14/2023]
Abstract
Background DFNB1, the first locus to have been associated with deafness, has two major genes GJB2 & GJB6, whose mutations have played vital role in hearing impairment across many ethnicities in the world. In our present study we have focused on the role of these mutations in assortative mating hearing impaired families from south India. Methods One hundred and six assortatively mating hearing impaired (HI) families of south Indian origin comprising of two subsets: 60 deaf marrying deaf (DXD) families and 46 deaf marrying normal hearing (DXN) families were recruited for this study. In the 60 DXD families, 335 members comprising of 118 HI mates, 63 other HI members and 154 normal hearing members and in the 46 DXN families, 281 members comprising of 46 HI and their 43 normal hearing partners, 50 other HI members and 142 normal hearing family members, participated in the molecular study. One hundred and sixty five (165) healthy normal hearing volunteers were recruited as controls for this study. All the participating members were screened for variants in GJB2 and GJB6 genes and the outcome of gene mutations were compared in the subsequent generation in begetting deaf offspring. Results The DFNB1 allele frequencies for DXD mates and their offspring were 36.98 and 38.67%, respectively and for the DXN mates and their offspring were 22.84 and 24.38%, respectively. There was a 4.6% increase in the subsequent generation in the DXD families, while a 6.75% increase in the DXN families, which demonstrates the role of assortative mating along with consanguinity in the increase of DFNB1 mutations in consecutive generations. Four novel variants, p.E42D (in GJB2 gene), p.Q57R, p.E101Q, p.R104H (in GJB6 gene) were also identified in this study. Conclusion This is the first study from an Indian subcontinent reporting novel variants in the coding region of GJB6 gene. This is perhaps the first study in the world to test real-time, the hypothesis proposed by Nance et al. in 2000 (intense phenotypic assortative mating mechanism can double the frequency of the commonest forms of recessive deafness [DFNB1]) in assortative mating HI parental generation and their offspring.
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Affiliation(s)
- Pavithra Amritkumar
- Department of Genetics, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai, 600113, India.,Current affiliation: PG and Research Department of Biotechnology, Women's Christian College, Chennai, India
| | - Justin Margret Jeffrey
- Department of Genetics, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai, 600113, India
| | - Jayasankaran Chandru
- Department of Genetics, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai, 600113, India
| | - Paridhy Vanniya S
- Department of Genetics, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai, 600113, India
| | - M Kalaimathi
- Department of Genetics, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai, 600113, India
| | - Rajagopalan Ramakrishnan
- Department of ENT, SRM Medical College Hospital and Research Centre, SRM Institute of Science and Technology, Kattankulathur, India
| | - N P Karthikeyen
- DOAST Hearing Care Center, Anna Nagar, Chennai, 600040, India
| | - C R Srikumari Srisailapathy
- Department of Genetics, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai, 600113, India.
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Miller ME, Lopez IA, Linthicum FH, Ishiyama A. Connexin 26 Immunohistochemistry in Temporal Bones With Cochlear Otosclerosis. Ann Otol Rhinol Laryngol 2018; 127:536-542. [PMID: 29911391 DOI: 10.1177/0003489418779410] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
HYPOTHESIS Connexin-26 (Cx26) expression is diminished in the spiral ligament of subjects with hearing loss and cochlear otosclerosis (CO). BACKGROUND Human temporal bone (HTB) studies have demonstrated that CO is associated with hyalinization of the spiral ligament. We hypothesize that hyalinization is associated with a loss of fibrocytes with a consequent decline in Cx26 expression. Cx26 and Connexin-30 (Cx30) encode gap junction proteins expressed in supporting cells of the organ of Corti, the spiral limbus, stria vascularis, and in fibrocytes of the spiral ligament. These gap junctions are critical for potassium recycling and maintenance of the endocochlear potential. Diminished expression of these proteins would likely be associated with hearing dysfunction. METHODS Histopathology and clinical characteristics of 45 HTB specimens with CO and spiral ligament hyalinization were reviewed. Those with sensorineural or mixed hearing loss but normal or near-normal hair cell counts were analyzed with light microscopy, and Cx26-immunoreactive (IR) signal was qualitatively assessed. RESULTS H&E staining demonstrated hyalinization in the spiral ligament and loss of type II and type III fibrocytes. Cx26-IR was diminished throughout the cochlea affected with CO compared with normal controls. CONCLUSIONS Cx26-IR reduction in the spiral ligament of subjects with CO likely plays a role in hearing loss.
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Affiliation(s)
| | | | - Fred H Linthicum
- 3 University of California, Los Angeles, West Los Angeles, California, USA
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Shodo R, Hayatsu M, Koga D, Horii A, Ushiki T. Three-dimensional reconstruction of root cells and interdental cells in the rat inner ear by serial section scanning electron microscopy. Biomed Res 2018; 38:239-248. [PMID: 28794401 DOI: 10.2220/biomedres.38.239] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In the cochlea, a high K+ environment in the endolymph is essential for the maintenance of normal hearing function, and the transport of K+ ions through gap junctions of the cochlear epithelium is thought to play an important role in endolymphatic homeostasis. The aim of the present study was to demonstrate the three-dimensional (3D) ultrastructure of spiral ligament root cells and interdental cells, which are located at both ends of the gap junction system of the cochlea epithelium. Serial semi-thin sections of plastic-embedded rat cochlea were mounted on glass slides, stained with uranyl acetate and lead citrate, and observed by scanning electron microscopy (SEM) using the backscattered electron (BSE) mode. 3D reconstruction of BSE images of serial sections revealed that the root cells were linked together to form a branched structure like an elaborate "tree root" in the spiral ligament. The interdental cells were also connected to each other, forming a comb-shaped cellular network with a number of cellular strands in the spiral limbus. Furthermore, TEM studies of ultra-thin sections revealed the rich presence of gap junctions in both root cells and interdental cells. These findings suggest the possibility that both root cells and interdental cells contribute to K+ circulation as the end portion of the epithelial cell gap junction system of the cochlea.
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Affiliation(s)
- Ryusuke Shodo
- Division of Microscopic Anatomy, Niigata University Graduate School of Medical and Dental Sciences.,Department of Otolaryngology Head and Neck Surgery, Niigata University Graduate School of Medical and Dental Sciences
| | - Manabu Hayatsu
- Division of Microscopic Anatomy, Niigata University Graduate School of Medical and Dental Sciences
| | - Daisuke Koga
- Department of Microscopic Anatomy and Cell Biology, Asahikawa Medical University
| | - Arata Horii
- Department of Otolaryngology Head and Neck Surgery, Niigata University Graduate School of Medical and Dental Sciences
| | - Tatsuo Ushiki
- Division of Microscopic Anatomy, Niigata University Graduate School of Medical and Dental Sciences
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Chen S, Xie L, Xu K, Cao HY, Wu X, Xu XX, Sun Y, Kong WJ. Developmental abnormalities in supporting cell phalangeal processes and cytoskeleton in the Gjb2 knockdown mouse model. Dis Model Mech 2018; 11:dmm.033019. [PMID: 29361521 PMCID: PMC5894950 DOI: 10.1242/dmm.033019] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 01/15/2018] [Indexed: 12/30/2022] Open
Abstract
Mutations in the GJB2 gene [which encodes connexin 26 (Cx26)] are the most common causes of hereditary hearing loss in humans, and previous studies showed postnatal development arrest of the organ of Corti in different Cx26-null mouse models. To explore the pathological changes and the mechanism behind the cochlear abnormalities in these mice further, we established transgenic mouse models by conditional knockdown of cochlear Cx26 at postnatal day (P) 0 and P8. Auditory brainstem responses were recorded and the morphological features in the organ of Corti were analyzed 18 days after Cx26 knockdown. Mice in the P0 knockdown group displayed severe hearing loss at all frequencies, whereas mice in the P8 knockdown group showed nearly normal hearing. In the P8 knockdown group, the organ of Corti displayed normal architecture, and no ultrastructural changes were observed. In the P0 knockdown group, the phalangeal processes of Deiter's cells did not develop into finger-like structures, and the formation of microtubules in the pillar cells was significantly reduced; moreover, the amount of acetylated α-tubulin was reduced in pillar cells. Our results indicate that Gjb2 participates in postnatal development of the cytoskeleton in pillar cells during structural maturation of the organ of Corti. In P0 knockdown mice, the reduction in microtubules in pillar cells might be responsible for the failure of the tunnel of Corti to open, and the malformed phalangeal processes might negatively affect the supporting framework of the organ of Corti, which would be a new mechanism of Gjb2-related hearing loss. Summary: A reduction in connexin 26 before opening of the tunnel of Corti impedes microtubule formation in supporting cells, and this may lead to cochlear developmental abnormalities and deafness in the Gjb2 knockdown mouse model.
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Affiliation(s)
- Sen Chen
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Le Xie
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Kai Xu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Hai-Yan Cao
- Department of Ultrasound, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xia Wu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xiao-Xiang Xu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China .,Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Wei-Jia Kong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China .,Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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48
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Lin J, Huang H, Lv G, Xu X, Lin W, Xu X, Cheng J, Zheng M. Chronic prenatal hypoxia impairs cochlear development, a mechanism involving connexin26 expression and promoter methylation. Int J Mol Med 2017; 41:852-858. [PMID: 29207085 PMCID: PMC5752184 DOI: 10.3892/ijmm.2017.3303] [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: 07/12/2017] [Accepted: 11/02/2017] [Indexed: 12/31/2022] Open
Abstract
Chronic prenatal hypoxia is a damaging to fetal development and may have various consequences, including hearing loss. Connexin 26 (Cx26) is one of the major protein subunits required for gap junction formation, and has an important role in maintaining homeostasis in the cochlea and normal hearing. Cx26 mutation and expression abnormality are closely associated with inherited nonsyndromic deafness, but the association between Cx26 and prenatal hypoxia is less established. The present study aimed to examine Cx26 expression and aberrant methylation the Cx26 promoter region in the cochlea from rats exposed to chronic prenatal hypoxia. Hematoxylin and eosin staining demonstrated that the number of hair cells in the organ of Corti were less in the hypoxia group. Reverse transcription-quantitative polymerase chain reaction and western blot analysis revealed that protein and mRNA levels of Cx26 were decreased in the hypoxia group compared with the control group. Further bisulfite sequencing analysis revealed that prenatal hypoxia significantly increased the methylation status of the promoter region of the Cx26 gene. These results demonstrate that chronic prenatal hypoxia caused hearing impairment, and suggest that promoter region hypermethylation and expression downregulation of Cx26 underlie the mechanism of action.
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Affiliation(s)
- Jingcang Lin
- Department of Anatomy, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, Fujian 350004, P.R. China
| | - Huang Huang
- Department of Histology and Embryology, Quanzhou Medical College, Quanzhou, Fujian 362100, P.R. China
| | - Guorong Lv
- Department of Medical Imaging, Quanzhou Medical College, Quanzhou, Fujian 362100, P.R. China
| | - Xiangyang Xu
- Department of Histology and Embryology, Quanzhou Medical College, Quanzhou, Fujian 362100, P.R. China
| | - Wendong Lin
- Department of Anatomy, Quanzhou Medical College, Quanzhou, Fujian 362100, P.R. China
| | - Xianyan Xu
- Department of Anatomy, Quanzhou Medical College, Quanzhou, Fujian 362100, P.R. China
| | - Jing Cheng
- Department of Histology and Embryology, Quanzhou Medical College, Quanzhou, Fujian 362100, P.R. China
| | - Ming Zheng
- Department of Anatomy, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, Fujian 350004, P.R. China
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49
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Zorzi V, Paciello F, Ziraldo G, Peres C, Mazzarda F, Nardin C, Pasquini M, Chiani F, Raspa M, Scavizzi F, Carrer A, Crispino G, Ciubotaru CD, Monyer H, Fetoni AR, M Salvatore A, Mammano F. Mouse Panx1 Is Dispensable for Hearing Acquisition and Auditory Function. Front Mol Neurosci 2017; 10:379. [PMID: 29234270 PMCID: PMC5712377 DOI: 10.3389/fnmol.2017.00379] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 10/30/2017] [Indexed: 11/13/2022] Open
Abstract
Panx1 forms plasma membrane channels in brain and several other organs, including the inner ear. Biophysical properties, activation mechanisms and modulators of Panx1 channels have been characterized in detail, however the impact of Panx1 on auditory function is unclear due to conflicts in published results. To address this issue, hearing performance and cochlear function of the Panx1−/− mouse strain, the first with a reported global ablation of Panx1, were scrutinized. Male and female homozygous (Panx1−/−), hemizygous (Panx1+/−) and their wild type (WT) siblings (Panx1+/+) were used for this study. Successful ablation of Panx1 was confirmed by RT-PCR and Western immunoblotting in the cochlea and brain of Panx1−/− mice. Furthermore, a previously validated Panx1-selective antibody revealed strong immunoreactivity in WT but not in Panx1−/− cochleae. Hearing sensitivity, outer hair cell-based “cochlear amplifier” and cochlear nerve function, analyzed by auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) recordings, were normal in Panx1+/− and Panx1−/− mice. In addition, we determined that global deletion of Panx1 impacts neither on connexin expression, nor on gap-junction coupling in the developing organ of Corti. Finally, spontaneous intercellular Ca2+ signal (ICS) activity in organotypic cochlear cultures, which is key to postnatal development of the organ of Corti and essential for hearing acquisition, was not affected by Panx1 ablation. Therefore, our results provide strong evidence that, in mice, Panx1 is dispensable for hearing acquisition and auditory function.
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Affiliation(s)
- Veronica Zorzi
- CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy.,School of Medicine, Institute of Otolaryngology, Catholic University, Rome, Italy
| | - Fabiola Paciello
- CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy
| | - Gaia Ziraldo
- CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy.,School of Medicine, Institute of Otolaryngology, Catholic University, Rome, Italy
| | - Chiara Peres
- CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy
| | - Flavia Mazzarda
- CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy.,Department of Science, Roma Tre University, Rome, Italy
| | - Chiara Nardin
- CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy.,Department of Science, Roma Tre University, Rome, Italy
| | - Miriam Pasquini
- CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy.,Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Francesco Chiani
- CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy
| | - Marcello Raspa
- CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy
| | | | - Andrea Carrer
- Department of Physics and Astronomy G. Galilei, University of Padua, Padua, Italy
| | - Giulia Crispino
- Department of Physics and Astronomy G. Galilei, University of Padua, Padua, Italy
| | | | - Hannah Monyer
- Department of Clinical Neurobiology, Deutches Krebforschungzentrum, University of Heidelberg, Heidelberg, Germany
| | - Anna R Fetoni
- School of Medicine, Institute of Otolaryngology, Catholic University, Rome, Italy
| | - Anna M Salvatore
- CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy
| | - Fabio Mammano
- CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy.,Department of Physics and Astronomy G. Galilei, University of Padua, Padua, Italy.,Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China
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50
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Effects of Retinoid Treatment on Cochlear Development, Connexin Expression and Hearing Thresholds in Mice. JOURNAL OF OTORHINOLARYNGOLOGY, HEARING AND BALANCE MEDICINE 2017. [DOI: 10.3390/ohbm1010002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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