1
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Leighton SE, Wong RS, Lucaciu SA, Hauser A, Johnston D, Stathopulos PB, Bai D, Penuela S, Laird DW. Cx31.1 can selectively intermix with co-expressed connexins to facilitate its assembly into gap junctions. J Cell Sci 2024; 137:jcs261631. [PMID: 38533727 PMCID: PMC11058089 DOI: 10.1242/jcs.261631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 03/05/2024] [Indexed: 03/28/2024] Open
Abstract
Connexins are channel-forming proteins that function to facilitate gap junctional intercellular communication. Here, we use dual cell voltage clamp and dye transfer studies to corroborate past findings showing that Cx31.1 (encoded by GJB5) is defective in gap junction channel formation, illustrating that Cx31.1 alone does not form functional gap junction channels in connexin-deficient mammalian cells. Rather Cx31.1 transiently localizes to the secretory pathway with a subpopulation reaching the cell surface, which is rarely seen in puncta reminiscent of gap junctions. Intracellular retained Cx31.1 was subject to degradation as Cx31.1 accumulated in the presence of proteasomal inhibition, had a faster turnover when Cx43 was present and ultimately reached lysosomes. Although intracellularly retained Cx31.1 was found to interact with Cx43, this interaction did not rescue its delivery to the cell surface. Conversely, the co-expression of Cx31 dramatically rescued the assembly of Cx31.1 into gap junctions where gap junction-mediated dye transfer was enhanced. Collectively, our results indicate that the localization and functional status of Cx31.1 is altered through selective interplay with co-expressed connexins, perhaps suggesting Cx31.1 is a key regulator of intercellular signaling in keratinocytes.
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Affiliation(s)
- Stephanie E. Leighton
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Robert S. Wong
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Sergiu A. Lucaciu
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Alexandra Hauser
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Danielle Johnston
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Peter B. Stathopulos
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Donglin Bai
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
- Western's Bone and Joint Institute, The Dr. Sandy Kirkley Centre for Musculoskeletal Research, University Hospital, London, ON N6A 5B9, Canada
- Division of Experimental Oncology, Department of Oncology, University of Western Ontario, London, ON N6A 5W9, Canada
| | - Dale W. Laird
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
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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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Defourny J, Thiry M. Recent insights into gap junction biogenesis in the cochlea. Dev Dyn 2023; 252:239-246. [PMID: 36106826 DOI: 10.1002/dvdy.538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 09/08/2022] [Accepted: 09/11/2022] [Indexed: 11/06/2022] Open
Abstract
In the cochlea, connexin 26 (Cx26) and connexin 30 (Cx30) co-assemble into two types of homomeric and heteromeric gap junctions between adjacent non-sensory epithelial cells. These channels provide a mechanical coupling between connected cells, and their activity is critical to maintain cochlear homeostasis. Many of the mutations in GJB2 or GJB6, which encode Cx26 and Cx30 in humans, impair the formation of membrane channels and cause autosomal syndromic and non-syndromic hearing loss. Thus, deciphering the connexin trafficking pathways in situ should represent a major step forward in understanding the pathogenic significance of many of these mutations. A growing body of evidence now suggests that Cx26/Cx30 heteromeric and Cx30 homomeric channels display distinct assembly mechanisms. Here, we review the most recent advances that have been made toward unraveling the biogenesis and stability of these gap junctions in the cochlea.
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Affiliation(s)
- Jean Defourny
- GIGA-Neurosciences, Unit of Cell and Tissue Biology, University of Liège, Liège, Belgium
| | - Marc Thiry
- GIGA-Neurosciences, Unit of Cell and Tissue Biology, University of Liège, Liège, Belgium
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4
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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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5
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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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6
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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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7
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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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8
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Huang S, Zhao G, Wu J, Li K, Wang Q, Fu Y, Zhang H, Bi Q, Li X, Wang W, Guo C, Zhang D, Wu L, Li X, Xu H, Han M, Wang X, Lei C, Qiu X, Li Y, Li J, Dai P, Yuan Y. Gene4HL: An Integrated Genetic Database for Hearing Loss. Front Genet 2021; 12:773009. [PMID: 34733322 PMCID: PMC8558372 DOI: 10.3389/fgene.2021.773009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 09/28/2021] [Indexed: 11/18/2022] Open
Abstract
Hearing loss (HL) is one of the most common disabilities in the world. In industrialized countries, HL occurs in 1–2/1,000 newborns, and approximately 60% of HL is caused by genetic factors. Next generation sequencing (NGS) has been widely used to identify many candidate genes and variants in patients with HL, but the data are scattered in multitudinous studies. It is a challenge for scientists, clinicians, and biologists to easily obtain and analyze HL genes and variant data from these studies. Thus, we developed a one-stop database of HL-related genes and variants, Gene4HL (http://www.genemed.tech/gene4hl/), making it easy to catalog, search, browse and analyze the genetic data. Gene4HL integrates the detailed genetic and clinical data of 326 HL-related genes from 1,608 published studies, along with 62 popular genetic data sources to provide comprehensive knowledge of candidate genes and variants associated with HL. Additionally, Gene4HL supports the users to analyze their own genetic engineering network data, performs comprehensive annotation, and prioritizes candidate genes and variations using custom parameters. Thus, Gene4HL can help users explain the function of HL genes and the clinical significance of variants by correlating the genotypes and phenotypes in humans.
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Affiliation(s)
- Shasha Huang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Guihu Zhao
- National Clinical Research Center for Geriatric Disorders, Department of Geriatrics, Xiangya Hospital, Central South University, Changsha, China.,Center for Medical Genetics & Hunan Key Laboratory, School of Life Sciences, Central South University, Changsha, China
| | - Jie Wu
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Kuokuo Li
- National Clinical Research Center for Geriatric Disorders, Department of Geriatrics, Xiangya Hospital, Central South University, Changsha, China.,Center for Medical Genetics & Hunan Key Laboratory, School of Life Sciences, Central South University, Changsha, China
| | - Qiuquan Wang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Ying Fu
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Honglei Zhang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Qingling Bi
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Xiaohong Li
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Weiqian Wang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Chang Guo
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Dejun Zhang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Lihua Wu
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Xiaoge Li
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Huiyan Xu
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Mingyu Han
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Xin Wang
- Angen Gene Medicine Technology Co., Ltd., Beijing, China
| | - Chen Lei
- Angen Gene Medicine Technology Co., Ltd., Beijing, China
| | - Xiaofang Qiu
- Angen Gene Medicine Technology Co., Ltd., Beijing, China
| | - Yang Li
- Angen Gene Medicine Technology Co., Ltd., Beijing, China
| | - Jinchen Li
- National Clinical Research Center for Geriatric Disorders, Department of Geriatrics, Xiangya Hospital, Central South University, Changsha, China.,Center for Medical Genetics & Hunan Key Laboratory, School of Life Sciences, Central South University, Changsha, China
| | - Pu Dai
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Yongyi Yuan
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, China
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9
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Unal YC, Yavuz B, Ozcivici E, Mese G. The role of connexins in breast cancer: from misregulated cell communication to aberrant intracellular signaling. Tissue Barriers 2021; 10:1962698. [PMID: 34355641 DOI: 10.1080/21688370.2021.1962698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
In spite of clinical advancements and improved diagnostic techniques, breast cancers are the leading cause of cancer-associated deaths in women worldwide. Although 70% of early breast cancers can be cured, there are no efficient therapies against metastatic breast cancers. Several factors including connexins and gap junctions play roles in breast tumorigenesis. Connexins are critical for cellular processes as a linkage between connexin mutations and hereditary disorders demonstrated their importance for tissue homeostasis. Further, alterations in their expression, localization and channel activities were observed in many cancers including breast cancer. Both channel-dependent and independent functions of connexins were reported in initiation and progression of cancers. Unlike initial reports suggesting tumor suppressor functions, connexins and gap junctions have stage, context and isoform dependent effects in breast cancers similar to other cancers. In this review, we tried to describe the current understanding of connexins in tumorigenesis specifically in breast cancers.
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Affiliation(s)
- Yagmur Ceren Unal
- Faculty of Science, Department of Molecular Biology and Genetics, Izmir Institute of Technology, Urla, Izmir, Turkey
| | - Busra Yavuz
- Faculty of Science, Department of Molecular Biology and Genetics, Izmir Institute of Technology, Urla, Izmir, Turkey
| | - Engin Ozcivici
- Department of Bioengineering, Faculty of Engineering, Izmir Institute of Technology, Urla, Izmir, Turkey
| | - Gulistan Mese
- Faculty of Science, Department of Molecular Biology and Genetics, Izmir Institute of Technology, Urla, Izmir, Turkey
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10
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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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11
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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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12
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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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13
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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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14
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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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15
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Chatterjee S, Mukherjee S, Sankara Sivaprasad LVJ, Naik T, Gautam SS, Murali BV, Hadambar AA, Gunti GR, Kuchibhotla V, Deyati A, Basavanthappa S, Ramarao M, Mariappan TT, Zinker BA, Zhang Y, Sinz M, Shen H. Transporter Activity Changes in Nonalcoholic Steatohepatitis: Assessment with Plasma Coproporphyrin I and III. J Pharmacol Exp Ther 2020; 376:29-39. [PMID: 33127749 DOI: 10.1124/jpet.120.000291] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/13/2020] [Indexed: 12/15/2022] Open
Abstract
Expression and functional changes in the organic anion transporting polypeptide (OATP)-multidrug resistance-associated protein (MRP) axis of transporters are well reported in patients with nonalcoholic steatohepatitis (NASH). These changes can impact plasma and tissue disposition of endo- and exogenous compounds. The transporter alterations are often assessed by administration of a xenobiotic or by transporter proteomic analysis from liver biopsies. Using gene expression, proteomics, and endogenous biomarkers, we show that the gene expression and activity of OATP and MRP transporters are associated with disease progression and recovery in humans and in preclinical animal models of NASH. Decreased OATP and increased MRP3/4 gene expression in two cohorts of patients with steatosis and NASH, as well as gene and protein expression in multiple NASH rodent models, have been established. Coproporphyrin I and III (CP I and III) were established as substrates of MRP4. CP I plasma concentration increased significantly in four animal models of NASH, indicating the transporter changes. Up to a 60-fold increase in CP I plasma concentration was observed in the mouse bile duct-ligated model compared with sham controls. In the choline-deficient amino acid-defined high-fat diet (CDAHFD) model, CP I plasma concentrations increased by >3-fold compared with chow diet-fed mice. In contrast, CP III plasma concentrations remain unaltered in the CDAHFD model, although they increased in the other three NASH models. These results suggest that tracking CP I plasma concentrations can provide transporter modulation information at a functional level in NASH animal models and in patients. SIGNIFICANCE STATEMENT: Our analysis demonstrates that multidrug resistance-associated protein 4 (MRP4) transporter gene expression tracks with nonalcoholic steatohepatitis (NASH) progression and intervention in patients. Additionally, we show that coproporphyrin I and III (CP I and III) are substrates of MRP4. CP I plasma and liver concentrations increase in different diet- and surgery-induced rodent NASH models, likely explained by both gene- and protein-level changes in transporters. CP I and III are therefore potential plasma-based biomarkers that can track NASH progression in preclinical models and in humans.
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Affiliation(s)
- Sagnik Chatterjee
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - Sambuddho Mukherjee
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - L V J Sankara Sivaprasad
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - Tanvi Naik
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - Shashyendra Singh Gautam
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - Bokka Venkata Murali
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - Avinash Annasao Hadambar
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - Gowtham Raj Gunti
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - Vijaykumar Kuchibhotla
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - Avisek Deyati
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - Sushma Basavanthappa
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - Manjunath Ramarao
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - T Thanga Mariappan
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - Bradley A Zinker
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - Yueping Zhang
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - Michael Sinz
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
| | - Hong Shen
- Pharmaceutical Candidate Optimization (S.C., S.S.L.V.J., T.N., S.S.G., B.V.M.) and Discovery and Translational Medicine (S.M., A.A.H., G.R.G., V.K., A.D., S.B.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India; Pharmaceutical Candidate Optimization (T.T.M.) and Discovery and Translational Medicine, Bristol-Myers Squibb India Pvt. Ltd. (M.R.), Biocon Bristol-Myers Squibb R&D Center (BBRC), Bangalore, India; BMS Fibrosis Drug Discovery, Research and Early Development, Princeton, New Jersey (B.A.Z.); and Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, New Jersey (Y.Z., M.S., H.S.)
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16
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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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17
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Abitbol J, Beach R, Barr K, Esseltine J, Allman B, Laird D. Cisplatin-induced ototoxicity in organotypic cochlear cultures occurs independent of gap junctional intercellular communication. Cell Death Dis 2020; 11:342. [PMID: 32393745 PMCID: PMC7214471 DOI: 10.1038/s41419-020-2551-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 04/23/2020] [Accepted: 04/23/2020] [Indexed: 12/11/2022]
Abstract
Cisplatin is a very effective chemotherapeutic, but severe and permanent hearing loss remains a prevalent side effect. The processes underpinning cisplatin-induced ototoxicity are not well understood. Gap junction channels composed of connexin (Cx) subunits allow for the passage of small molecules and ions between contacting neighboring cells. These specialized channels have been postulated to enhance cisplatin-induced cell death by spreading “death signals” throughout the supporting cells of the organ of Corti. This study sought to investigate the role of Cx43 in cisplatin-induced ototoxicity using organotypic cochlear cultures from control and two Cx43-mutant mouse strains harboring either a moderate (Cx43I130T/+) or severe (Cx43G60S/+) reduction of Cx43 function. Cochlear cultures from Cx43-mutant mice with a severe reduction in Cx43-based gap junctional intercellular communication (GJIC) had an enhanced number of hair cells that were positive for cleaved caspase 3, a marker of active apoptosis, after cisplatin treatment. In cisplatin-treated organotypic cochlear cultures, there was a decrease in the co-localization of Cx26 and Cx30 compared with untreated cultures, suggesting that cisplatin causes reorganization of connexin composition in supporting cells. Both Cx26 and Cx30 protein expression as well as GJIC were decreased in organotypic cochlear cultures treated with the gap-junction blocker carbenoxolone. When cisplatin and carbenoxolone were co-administered, there were no differences in hair cell loss compared with cisplatin treatment alone. Using cisplatin-treated control and Cx43-ablated organ of Corti derived HEI-OC1 mouse cells, we found that greatly reducing GJIC led to preferential induction of an ER stress pathway. Taken together, this study strongly suggests that inhibition of GJIC in organ of Corti cells does not lead to differential susceptibility to cisplatin-induced ototoxicity. Although cisplatin causes the same degree of cell death in gap junction competent and incompetent cochlear cells, the engagement of the mitochondrial dysregulation and ER stress differs.
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Affiliation(s)
- Julia Abitbol
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1, Canada
| | - Rianne Beach
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1, Canada
| | - Kevin Barr
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1, Canada
| | - Jessica Esseltine
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, A1B 3V6, Canada
| | - Brian Allman
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1, Canada
| | - Dale Laird
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1, Canada.
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Prenatal electroporation-mediated gene transfer restores Slc26a4 knock-out mouse hearing and vestibular function. Sci Rep 2019; 9:17979. [PMID: 31784581 PMCID: PMC6884448 DOI: 10.1038/s41598-019-54262-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 11/08/2019] [Indexed: 12/13/2022] Open
Abstract
The otocyst, an anlage of the inner ear, presents an attractive target to study treatment strategies for genetic hearing loss and inner ear development. We have previously reported that electroporation-mediated transuterine gene transfer of Connexin30, utilizing a monophasic pulse into Connexin30−/− mouse otocysts at embryonic day 11.5, is able to prevent putative hearing deterioration. However, it is not clear whether supplementary gene transfer can rescue significant morphological changes, caused by genetic deficits. In addition, with the transuterine gene transfer technique utilized in our previous report, the survival rate of embryos and their mothers after treatment was low, which became a serious obstacle for effective in vivo experiments. Here, we set out to elucidate the feasibility of supplementation therapy in Slc26a4 deficient mice, utilizing biphasic pulses, optimized by modifying pulse conditions. Modification of the biphasic pulse conditions during electroporation increased the survival rate. In addition, supplementation of the target gene cDNA into the otocysts of homozygous Slc24a4 knockout mice significantly prevented enlargement of the endolymphatic space in the inner ear areas; moreover, it rescued hearing and vestibular function of mice in vivo.
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19
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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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20
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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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Inner Ear Connexin Channels: Roles in Development and Maintenance of Cochlear Function. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a033233. [PMID: 30181354 DOI: 10.1101/cshperspect.a033233] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [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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22
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Xie L, Chen S, Xu K, Cao HY, Du AN, Bai X, Sun Y, Kong WJ. Reduced postnatal expression of cochlear Connexin26 induces hearing loss and affects the developmental status of pillar cells in a dose-dependent manner. Neurochem Int 2019; 128:196-205. [PMID: 31034913 DOI: 10.1016/j.neuint.2019.04.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 04/17/2019] [Accepted: 04/19/2019] [Indexed: 10/26/2022]
Abstract
Mutations in the GJB2 gene (which encodes Connexin26 (Cx26)) are the most common cause of non-syndromic deafness. Previous studies showed that an extensive knockout of the Gjb2 gene in cochlear epithelium can cause severe deafness, significant hair cell (HC) loss and failure of pillar cells (a type of supporting cell, PCs) to differentiate in mice. This study aimed to establish different mouse models with gradient reductions of cochlear Cx26 expression and to investigate the effect of different reduced levels of cochlear Cx26 expression on hearing and development of PCs. According to the reduction in the levels of cochlear Cx26, these models were named high knockdown (KD), middle KD and low KD group. In the low KD group, the mice showed normal hearing and well-developed PCs. In the high KD group, up to 90 percent of supporting cells (SCs) lost Cx26 expression. These mice exhibited severe deafness, rapid hair cell degeneration and juvenile PCs. In the middle KD group, nearly half of SCs lost Cx26 expression. However, these mice showed a moderate deafness and a late-onset hair cell loss. Moreover, nearly all the PCs in mice of this group were in a partially differentiated state. These results indicated that reduction of postnatal expression of cochlear Cx26 induces hearing loss in a dose-dependent manner. Null Cx26 in a few SCs affects the developmental status of PCs and the hair cell degeneration pattern. The abnormal developmental status of PCs may be a potential cause of Gjb2-related hearing loss.
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Affiliation(s)
- Le Xie
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Sen Chen
- 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
| | - An-Na Du
- Centre of Instrumental Analysis and Metrology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Xue Bai
- 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.
| | - 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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23
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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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24
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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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25
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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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26
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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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27
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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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Zhang W, Kim SM, Wang W, Cai C, Feng Y, Kong W, Lin X. Cochlear Gene Therapy for Sensorineural Hearing Loss: Current Status and Major Remaining Hurdles for Translational Success. Front Mol Neurosci 2018; 11:221. [PMID: 29997477 PMCID: PMC6028713 DOI: 10.3389/fnmol.2018.00221] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 06/06/2018] [Indexed: 12/19/2022] Open
Abstract
Sensorineural hearing loss (SNHL) affects millions of people. Genetic mutations play a large and direct role in both congenital and late-onset cases of SNHL (e.g., age-dependent hearing loss, ADHL). Although hearing aids can help moderate to severe hearing loss the only effective treatment for deaf patients is the cochlear implant (CI). Gene- and cell-based therapies potentially may preserve or restore hearing with more natural sound perception, since their theoretical frequency resolution power is much higher than that of cochlear implants. These biologically-based interventions also carry the potential to re-establish hearing without the need for implanting any prosthetic device; the convenience and lower financial burden afforded by such biologically-based interventions could potentially benefit far more SNHL patients. Recently major progress has been achieved in preclinical studies of cochlear gene therapy. This review critically evaluates recent advances in the preclinical trials of gene therapies for SNHL and the major remaining challenges for the development and eventual clinical translation of this novel therapy. The cochlea bears many similarities to the eye for translational studies of gene therapies. Experience gained in ocular gene therapy trials, many of which have advanced to clinical phase III, may provide valuable guidance in improving the chance of success for cochlear gene therapy in human trials. A discussion on potential implications of translational knowledge gleaned from large numbers of advanced clinical trials of ocular gene therapy is therefore included.
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Affiliation(s)
- Wenjuan Zhang
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Sun Myoung Kim
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
| | - Wenwen Wang
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | | | - Yong Feng
- Xiangya School of Medicine, Changsha, China
| | - Weijia Kong
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xi Lin
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
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Abstract
Major depressive disorder (MDD) is a chronic and debilitating illness that affects over 350 million people worldwide; however, current treatments have failed to cure or prevent the progress of depression. Increasing evidence suggests a crucial role for connexins in MDD. In this review, we have summarised recent accomplishments regarding the role of connexins, gap junctions, and hemichannels in the aetiology of MDD, and discussed the limitations of current research. A blockage of gap junctions or hemichannels induces depressive behaviour. Possible underlying mechanisms include the regulation of neurosecretory functions and synaptic activity by gap junctions and hemichannels. Gap junctions are functionally inhibited under stress conditions. Conversely, hemichannel permeability is increased. Antidepressants inhibit hemichannel permeability; however, they have contrasting effects on the function of gap junctions under normal conditions and can protect them against stress. In conclusion, the blockage of hemichannels concurrent with improvements in gap junction functionality might be potential targets for depression treatment.
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Affiliation(s)
- Cong-Yuan Xia
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Zhen-Zhen Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Tohru Yamakuni
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China; College of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan 410208, China.
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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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31
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Verselis VK. Connexin hemichannels and cochlear function. Neurosci Lett 2017; 695:40-45. [PMID: 28917982 DOI: 10.1016/j.neulet.2017.09.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 07/24/2017] [Accepted: 09/10/2017] [Indexed: 01/01/2023]
Abstract
Connexins play vital roles in hearing, including promoting cochlear development and sustaining auditory function in the mature cochlea. Mutations in connexins expressed in the cochlear epithelium, Cx26 and Cx30, cause sensorineural deafness and in the case of Cx26, is one of the most common causes of non-syndromic, hereditary deafness. Connexins function as gap junction channels and as hemichannels, which mediate intercellular and transmembrane signaling, respectively. Both channel configurations can play important, but very different roles in the cochlea. The potential roles connexin hemichannels can play are discussed both in normal cochlear function and in promoting pathogenesis that can lead to hearing loss.
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Affiliation(s)
- Vytas K Verselis
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, United States.
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Liu W, Li H, Edin F, Brännström J, Glueckert R, Schrott-Fischer A, Molnar M, Pacholsky D, Pfaller K, Rask-Andersen H. Molecular composition and distribution of gap junctions in the sensory epithelium of the human cochlea-a super-resolution structured illumination microscopy (SR-SIM) study. Ups J Med Sci 2017; 122:160-170. [PMID: 28513246 PMCID: PMC5649321 DOI: 10.1080/03009734.2017.1322645] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/29/2022] Open
Abstract
BACKGROUND Mutations in the GJB2 gene, which encodes the Connexin26 (Cx26) protein, are the most common cause of childhood hearing loss in American and European populations. The cochlea contains a gap junction (GJ) network in the sensory epithelium and two connective tissue networks in the lateral wall and spiral limbus. The syncytia contain the GJ proteins beta 2 (GJB2/Cx26) and beta 6 (GJB6/Cx30). Our knowledge of their expression in humans is insufficient due to the limited availability of tissue. Here, we sought to establish the molecular arrangement of GJs in the epithelial network of the human cochlea using surgically obtained samples. METHODS We analyzed Cx26 and Cx30 expression in GJ networks in well-preserved adult human auditory sensory epithelium using confocal, electron, and super-resolution structured illumination microscopy (SR-SIM). RESULTS Cx30 plaques (<5 μm) dominated, while Cx26 plaques were subtle and appeared as 'mini-junctions' (2-300 nm). 3-D volume rendering of Z-stacks and orthogonal projections from single optical sections suggested that the GJs are homomeric/homotypic and consist of assemblies of identical GJs composed of either Cx26 or Cx30. Occasionally, the two protein types were co-expressed, suggesting functional cooperation. CONCLUSIONS Establishing the molecular composition and distribution of the GJ networks in the human cochlea may increase our understanding of the pathophysiology of Cx-related hearing loss. This information may also assist in developing future strategies to treat genetic hearing loss.
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Affiliation(s)
- Wei Liu
- Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Department of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden;
| | - Hao Li
- Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Department of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden;
| | - Fredrik Edin
- Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Department of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden;
| | - Johan Brännström
- Department of Immunology, Genetics and Pathology, The Rudbeck Laboratory, Uppsala University, Uppsala, Sweden;
| | - Rudolf Glueckert
- Department of Otolaryngology, Medical University of Innsbruck, Innsbruck, Austria;
| | | | - Matyas Molnar
- Science for Life Laboratory, BioVis Facility, Uppsala University, Uppsala, Sweden;
| | - Dirk Pacholsky
- Science for Life Laboratory, BioVis Facility, Uppsala University, Uppsala, Sweden;
| | - Kristian Pfaller
- Department of Histology and Molecular Cell Biology, Institute of Anatomy and Histology, Medical University of Innsbruck, Innsbruck, Austria
| | - Helge Rask-Andersen
- Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Department of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden;
- CONTACT Helge Rask-Andersen Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Department of Otolaryngology, Uppsala University Hospital, SE-751 85, Uppsala, Sweden
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Amplification mode differs along the length of the mouse cochlea as revealed by connexin 26 deletion from specific gap junctions. Sci Rep 2017; 7:5185. [PMID: 28701711 PMCID: PMC5507891 DOI: 10.1038/s41598-017-04279-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 05/17/2017] [Indexed: 01/26/2023] Open
Abstract
The sharp frequency tuning and exquisite sensitivity of the mammalian cochlea is due to active forces delivered by outer hair cells (OHCs) to the cochlear partition. Force transmission is mediated and modulated by specialized cells, including Deiters’ cells (DCs) and pillar cells (PCs), coupled by gap-junctions composed of connexin 26 (Cx26) and Cx30. We created a mouse with conditional Cx26 knock-out (Cx26 cKO) in DCs and PCs that did not influence sensory transduction, receptor-current-driving-voltage, low-mid-frequency distortion-product-otoacoustic-emissions (DPOAEs), and passive basilar membrane (BM) responses. However, the Cx26 cKO desensitizes mid-high-frequency DPOAEs and active BM responses and sensitizes low-mid-frequency neural excitation. This functional segregation may indicate that the flexible, apical turn cochlear partition facilitates transfer of OHC displacements (isotonic forces) for cochlear amplification and neural excitation. DC and PC Cx26 expression is essential for cochlear amplification in the stiff basal turn, possibly through maintaining cochlear partition mechanical impedance, thereby ensuring effective transfer of OHC isometric forces.
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Fukunaga I, Fujimoto A, Hatakeyama K, Aoki T, Nishikawa A, Noda T, Minowa O, Kurebayashi N, Ikeda K, Kamiya K. In Vitro Models of GJB2-Related Hearing Loss Recapitulate Ca 2+ Transients via a Gap Junction Characteristic of Developing Cochlea. Stem Cell Reports 2016; 7:1023-1036. [PMID: 27840044 PMCID: PMC5161531 DOI: 10.1016/j.stemcr.2016.10.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 10/12/2016] [Accepted: 10/13/2016] [Indexed: 12/24/2022] Open
Abstract
Mutation of the Gap Junction Beta 2 gene (GJB2) encoding connexin 26 (CX26) is the most frequent cause of hereditary deafness worldwide and accounts for up to 50% of non-syndromic sensorineural hearing loss cases in some populations. Therefore, cochlear CX26-gap junction plaque (GJP)-forming cells such as cochlear supporting cells are thought to be the most important therapeutic target for the treatment of hereditary deafness. The differentiation of pluripotent stem cells into cochlear CX26-GJP-forming cells has not been reported. Here, we detail the development of a novel strategy to differentiate induced pluripotent stem cells into functional CX26-GJP-forming cells that exhibit spontaneous ATP- and hemichannel-mediated Ca2+ transients typical of the developing cochlea. Furthermore, these cells from CX26-deficient mice recapitulated the drastic disruption of GJPs, the primary pathology of GJB2-related hearing loss. These in vitro models should be useful for establishing inner-ear cell therapies and drug screening that target GJB2-related hearing loss. Mutation in GJB2 (CX26) is the most frequent cause of hereditary deafness worldwide Functional CX26-gap junction plaque (GJP)-forming cells were generated from iPSCs These cells exhibited spontaneous Ca2+ transients typical of the developing cochlea The drastic disruption of GJP was observed in in vitro disease model of GJB2 mutation
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Affiliation(s)
- Ichiro Fukunaga
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan; Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Ayumi Fujimoto
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Kaori Hatakeyama
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Toru Aoki
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Atena Nishikawa
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Tetsuo Noda
- Department of Cell Biology, Japanese Foundation for Cancer Research, Cancer Institute, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan; Team for Advanced Development and Evaluation of Human Disease Models, RIKEN BioResource Center, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan
| | - Osamu Minowa
- Department of Cell Biology, Japanese Foundation for Cancer Research, Cancer Institute, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan; Team for Advanced Development and Evaluation of Human Disease Models, RIKEN BioResource Center, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan
| | - Nagomi Kurebayashi
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Katsuhisa Ikeda
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Kazusaku Kamiya
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
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35
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Tsai PC, Yang DM, Liao YC, Chiu TY, Kuo HC, Su YP, Guo YC, Soong BW, Lin KP, Liu YT, Lee YC. Clinical and biophysical characterization of 19 GJB1 mutations. Ann Clin Transl Neurol 2016; 3:854-865. [PMID: 27844031 PMCID: PMC5099531 DOI: 10.1002/acn3.347] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 08/08/2016] [Accepted: 08/08/2016] [Indexed: 12/12/2022] Open
Abstract
Objective Charcot–Marie–Tooth disease type X1 (CMTX1), which is caused by mutations in the gap junction (GJ) protein beta‐1 gene (GJB1), is the second most common form of Charcot–Marie–Tooth disease (CMT). GJB1 encodes the GJ beta‐1 protein (GJB1), which forms GJs within the myelin sheaths of peripheral nerves. The process by which GJB1 mutants cause neuropathy has not been fully elucidated. This study evaluated the biophysical characteristics of GJB1 mutants and their correlations with the clinical features of CMTX1 patients. Methods All patients with a validated GJB1 mutation were assessed using the Charcot–Marie–Tooth disease neuropathy score version 2 (CMTNS). The impacts of the mutations on the biophysical functions of GJB1 were characterized by assessing intracellular localization, expression patterns, and GJ Ca2+ permeability. Result Nineteen GJB1 mutations were identified in 24 patients with a clinical diagnosis of CMT. Six are novel mutations: p.L6S, p.I20F, p.I101Rfs*8, p.F153L, p.R215P, and p.D278V. Diverse pathological effects of the mutations were demonstrated, including reduced GJB1 expression, intracellular mislocalization, and altered GJ functions. GJB1 mutations that caused a complete loss of GJ Ca2+ permeability appeared to be associated with an earlier disease onset, whereas those resulting in preservation of GJ permeability and with predominant cell membrane expression tended to have a later onset and a milder phenotype. Interpretation This study demonstrated that the degree of loss of GJ function caused by the GJB1 mutations might contribute to the onset and severity of neuropathic symptoms in CMTX1.
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Affiliation(s)
- Pei-Chien Tsai
- Department of Neurology Taipei Veterans General Hospital Taipei 11217 Taiwan; Department of Neurology National Yang-Ming University School of Medicine Taipei 11221 Taiwan; Brain Research Center National Yang-Ming University Taipei 11221 Taiwan
| | - De-Ming Yang
- Microscopy Service Laboratory Basic Research Division Department of Medical Research and Education Taipei Veterans General Hospital Taipei 11217 Taiwan; Institute of Biophotonics School of Medical Technology & Engineering; Biophotonics and Molecular Imaging Research Center (BMIRC) National Yang-Ming University Taipei 11212 Taiwan
| | - Yi-Chu Liao
- Department of Neurology Taipei Veterans General Hospital Taipei 11217 Taiwan; Department of Neurology National Yang-Ming University School of Medicine Taipei 11221 Taiwan
| | - Tai-Yu Chiu
- Microscopy Service Laboratory Basic Research Division Department of Medical Research and Education Taipei Veterans General Hospital Taipei 11217 Taiwan; Institute of Biophotonics School of Medical Technology & Engineering; Biophotonics and Molecular Imaging Research Center (BMIRC) National Yang-Ming University Taipei 11212 Taiwan
| | - Hung-Chou Kuo
- Department of Neurology Chang Gung Memorial Hospital at Linkou Medical Center and Chang Gung University College of Medicine Taoyuan 33302 Taiwan
| | - Yu-Ping Su
- Department of Psychiatry Cathay General Hospital Taipei 10687 Taiwan; School of Medicine Fu-Jen Catholic University Taipei 24205 Taiwan
| | - Yuh-Cherng Guo
- Institute of Clinical Medicine National Yang-Ming University Taipei 11221 Taiwan; Neuroscience Laboratory Department of Neurology China Medical University Hospital Taichung 40447 Taiwan; School of Medicine College of Medicine China Medical University Taichung 40402 Taiwan
| | - Bing-Wen Soong
- Department of Neurology Taipei Veterans General Hospital Taipei 11217 Taiwan; Department of Neurology National Yang-Ming University School of Medicine Taipei 11221 Taiwan; Brain Research Center National Yang-Ming University Taipei 11221 Taiwan
| | - Kon-Ping Lin
- Department of Neurology Taipei Veterans General Hospital Taipei 11217 Taiwan; Department of Neurology National Yang-Ming University School of Medicine Taipei 11221 Taiwan
| | - Yo-Tsen Liu
- Department of Neurology Taipei Veterans General Hospital Taipei 11217 Taiwan; Department of Neurology National Yang-Ming University School of Medicine Taipei 11221 Taiwan
| | - Yi-Chung Lee
- Department of Neurology Taipei Veterans General Hospital Taipei 11217 Taiwan; Department of Neurology National Yang-Ming University School of Medicine Taipei 11221 Taiwan; Brain Research Center National Yang-Ming University Taipei 11221 Taiwan
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36
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Super-resolution structured illumination fluorescence microscopy of the lateral wall of the cochlea: the Connexin26/30 proteins are separately expressed in man. Cell Tissue Res 2016; 365:13-27. [DOI: 10.1007/s00441-016-2359-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 01/07/2016] [Indexed: 10/22/2022]
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Reduced Connexin26 in the Mature Cochlea Increases Susceptibility to Noise-Induced Hearing Lossin Mice. Int J Mol Sci 2016; 17:301. [PMID: 26927086 PMCID: PMC4813165 DOI: 10.3390/ijms17030301] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 02/15/2016] [Accepted: 02/22/2016] [Indexed: 01/17/2023] Open
Abstract
Connexin26 (Cx26, encoded by GJB2) mutations are the most common cause of non-syndromic deafness. GJB2 is thought to be involved in noise-induced hearing loss (NIHL). However, the role of Cx26 in NIHL is still obscure. To explore the association between Cx26 and NIHL, we established a Cx26 knockdown (KD) mouse model by conditional knockdown of Cx26 at postnatal day 18 (P18), and then we observed the auditory threshold and morphologic changes in these mice with or without noise exposure. The Cx26 KD mice did not exhibit substantial hearing loss and hair cell degeneration, while the Cx26 KD mice with acoustic trauma experienced higher hearing loss than simple noise exposure siblings and nearly had no recovery. Additionally, extensive outer hair cell loss and more severe destruction of the basal organ of Corti were observed in Cx26 KD mice after noise exposure. These data indicate that reduced Cx26 expression in the mature mouse cochlea may increase susceptibility to noise-induced hearing loss and facilitate the cell degeneration in the organ of Corti.
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38
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An electrostatic mechanism for Ca(2+)-mediated regulation of gap junction channels. Nat Commun 2016; 7:8770. [PMID: 26753910 PMCID: PMC4730032 DOI: 10.1038/ncomms9770] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 10/01/2015] [Indexed: 01/07/2023] Open
Abstract
Gap junction channels mediate intercellular signalling that is crucial in tissue development, homeostasis and pathologic states such as cardiac arrhythmias, cancer and trauma. To explore the mechanism by which Ca(2+) blocks intercellular communication during tissue injury, we determined the X-ray crystal structures of the human Cx26 gap junction channel with and without bound Ca(2+). The two structures were nearly identical, ruling out both a large-scale structural change and a local steric constriction of the pore. Ca(2+) coordination sites reside at the interfaces between adjacent subunits, near the entrance to the extracellular gap, where local, side chain conformational rearrangements enable Ca(2+)chelation. Computational analysis revealed that Ca(2+)-binding generates a positive electrostatic barrier that substantially inhibits permeation of cations such as K(+) into the pore. Our results provide structural evidence for a unique mechanism of channel regulation: ionic conduction block via an electrostatic barrier rather than steric occlusion of the channel pore.
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39
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Single nucleotide polymorphisms of the GJB2 and GJB6 genes are associated with autosomal recessive nonsyndromic hearing loss. BIOMED RESEARCH INTERNATIONAL 2015; 2015:318727. [PMID: 26075227 PMCID: PMC4449875 DOI: 10.1155/2015/318727] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 03/01/2015] [Indexed: 12/02/2022]
Abstract
Single nucleotide polymorphisms (SNPs) are important markers in many studies that link DNA sequence variations to phenotypic changes; such studies are expected to advance the understanding of human physiology and elucidate the molecular basis of diseases. The DFNB1 locus, which contains the GJB2 and GJB6 genes, plays a key role in nonsyndromic hearing loss. Previous studies have identified important mutations in this locus, but the contribution of SNPs in the genes has not yet been much investigated. The aim of this study was to investigate the association of nine polymorphisms located within the DFNB1 locus with the occurrence of autosomal recessive nonsyndromic hearing loss (ARNSHL). The SNPs rs3751385 (C/T), rs7994748 (C/T), rs7329857 (C/T), rs7987302 (G/A), rs7322538 (G/A), rs9315400 (C/T), rs877098 (C/T), rs945369 (A/C), and rs7333214 (T/G) were genotyped in 122 deaf patients and 132 healthy controls using allele-specific PCR. There were statistically significant differences between patients and controls, in terms of allelic frequencies in the SNPs rs3751385, rs7994748, rs7329857, rs7987302, rs945369, and rs7333214 (P < 0.05). No significant differences between the two groups were observed for rs7322538, rs9315400, and rs877098. Our results suggest that SNPs present in the GJB2 and GJB6 genes may have an influence on ARNSHL in humans.
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40
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Potential treatments for genetic hearing loss in humans: current conundrums. Gene Ther 2015; 22:603-9. [PMID: 25781649 DOI: 10.1038/gt.2015.27] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 01/24/2015] [Accepted: 02/12/2015] [Indexed: 12/18/2022]
Abstract
Genetic defects are a major cause of hearing loss in newborns. Consequently, hearing loss has a profound negative impact on human daily living. Numerous causative genes for genetic hearing loss have been identified. However, presently, there are no truly curative treatments for this condition. There have been several recent reports on successful treatments in mice using embryonic gene therapy, neonatal gene therapy and neonatal antisense oligonucleotide therapy. Herein, we describe state-of-the-art research on genetic hearing loss treatment through gene therapy and discuss the obstacles to overcome in curative treatments of genetic hearing loss in humans.
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Kelly JJ, Shao Q, Jagger DJ, Laird DW. Cx30 exhibits unique characteristics including a long half-life when assembled into gap junctions. J Cell Sci 2015; 128:3947-60. [DOI: 10.1242/jcs.174698] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 09/08/2015] [Indexed: 01/04/2023] Open
Abstract
In the present study we investigated the life-cycle, trafficking, assembly and cell surface dynamics of a poorly characterized connexin family member, connexin 30 (Cx30), which plays a critical role in skin health and hearing. Unexpectedly, Cx30 localization at the cell surface and gap junctional intercellular communication was not affected by prolonged treatments with the ER-Golgi transport inhibitor brefeldin-A or the protein synthesis inhibitor cycloheximide, whereas Cx43 was rapidly cleared. Fluorescent recovery after photobleaching revealed that Cx30 plaques were rebuilt from the outer edges in keeping with older channels residing in the inner core of the plaque. Expression of a dominant-negative form of Sar1 GTPase led to the accumulation of Cx30 within the ER in contrast to a report that Cx30 traffics via a Golgi-independent pathway. Co-expression of Cx30 with Cx43 revealed that these connexins segregate into distinct domains within common gap junction plaques suggesting their assembly is governed by different mechanisms. In summary, Cx30 was found to be an unusually stable, long-lived connexin (half-life >12 hrs), which may underlie its specific role in the epidermis and cochlea.
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Affiliation(s)
- John J. Kelly
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
| | - Qing Shao
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
| | | | - Dale W. Laird
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
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Kelly JJ, Simek J, Laird DW. Mechanisms linking connexin mutations to human diseases. Cell Tissue Res 2014; 360:701-21. [DOI: 10.1007/s00441-014-2024-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 09/26/2014] [Indexed: 11/30/2022]
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Jagger DJ, Forge A. Connexins and gap junctions in the inner ear--it's not just about K⁺ recycling. Cell Tissue Res 2014; 360:633-44. [PMID: 25381570 PMCID: PMC4452565 DOI: 10.1007/s00441-014-2029-z] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 10/06/2014] [Indexed: 12/19/2022]
Abstract
Normal development, function and repair of the sensory epithelia in the inner ear are all dependent on gap junctional intercellular communication. Mutations in the connexin genes GJB2 and GJB6 (encoding CX26 and CX30) result in syndromic and non-syndromic deafness via various mechanisms. Clinical vestibular defects, however, are harder to connect with connexin dysfunction. Cx26 and Cx30 proteins are widely expressed in the epithelial and connective tissues of the cochlea, where they may form homomeric or heteromeric gap junction channels in a cell-specific and spatiotemporally complex fashion. Despite the study of mutant channels and animal models for both recessive and dominant autosomal deafness, it is still unclear why gap junctions are essential for auditory function, and why Cx26 and Cx30 do not compensate for each other in vivo. Cx26 appears to be essential for normal development of the auditory sensory epithelium, but may be dispensable during normal hearing. Cx30 appears to be essential for normal repair following sensory cell loss. The specific modes of intercellular signalling mediated by inner ear gap junction channels remain undetermined, but they are hypothesised to play essential roles in the maintenance of ionic and metabolic homeostasis in the inner ear. Recent studies have highlighted involvement of gap junctions in the transfer of essential second messengers between the non-sensory cells, and have proposed roles for hemichannels in normal hearing. Here, we summarise the current knowledge about the molecular and functional properties of inner ear gap junctions, and about tissue pathologies associated with connexin mutations.
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Affiliation(s)
- Daniel J Jagger
- UCL Ear Institute, University College London, 332 Gray's Inn Road, London, WC1X 8EE, UK,
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Chang Q, Tang W, Kim Y, Lin X. Timed conditional null of connexin26 in mice reveals temporary requirements of connexin26 in key cochlear developmental events before the onset of hearing. Neurobiol Dis 2014; 73:418-27. [PMID: 25251605 DOI: 10.1016/j.nbd.2014.09.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 08/21/2014] [Accepted: 09/12/2014] [Indexed: 11/17/2022] Open
Abstract
Mutations in the Gjb2 gene, which encodes a gap junction protein connexin26 (Cx26), are the most prevalent form of hereditary deafness in humans and represent about half of non-syndromic congenital deafness cases in many ethnic populations. Cochlear potassium (K+) recycling in mature cochlea is required for normal hearing. It is thought that gap junctions are essential for K+ recycling and that Gjb2 mutations cause Gjb2-associated deafness by disrupting K+ recycling in mature cochlea. Here we present evidence showing that Gjb2 is required for normal development of the neonatal organ of Corti prior to the onset of the hearing in mice. In the conditional Gjb2 null (cCx26 null) mice, ribbon synapses in inner hair cells remained poorly developed, the afferent type I fibers failed to finish the refinement process to form convergent innervation to individual inner hair cells. The spontaneous depolarizing activities in the supporting cells, which normally diminish in the wild type cochleae after postnatal day 8 (P8), remained strong in the cochlea after P8 in the mutant mice. Furthermore, the deafness phenotype was readily generated only if the Cx26 expression in the organ of Corti was significantly reduced before P6. Similar amount of Cx26 reduction in more mature cochleae had a much weaker effect in damaging the hearing sensitivity. Our findings indicated that Cx26 plays essential roles in the maturation process of the organ of Corti prior to the establishment of high K+ in the endolymph and the onset of hearing. These results suggest that successful treatment of Cx26 deafness requires early intervention before the cochlea fully matures.
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Affiliation(s)
- Qing Chang
- Department of Otolaryngology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322-3030, USA
| | - Wenxue Tang
- Department of Otolaryngology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322-3030, USA
| | - Yeunjung Kim
- 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; Department of Cell Biology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322-3030, USA
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45
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Kamiya K, Yum SW, Kurebayashi N, Muraki M, Ogawa K, Karasawa K, Miwa A, Guo X, Gotoh S, Sugitani Y, Yamanaka H, Ito-Kawashima S, Iizuka T, Sakurai T, Noda T, Minowa O, Ikeda K. Assembly of the cochlear gap junction macromolecular complex requires connexin 26. J Clin Invest 2014; 124:1598-607. [PMID: 24590285 DOI: 10.1172/jci67621] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 01/02/2014] [Indexed: 12/18/2022] Open
Abstract
Hereditary deafness affects approximately 1 in 2,000 children. Mutations in the gene encoding the cochlear gap junction protein connexin 26 (CX26) cause prelingual, nonsyndromic deafness and are responsible for as many as 50% of hereditary deafness cases in certain populations. Connexin-associated deafness is thought to be the result of defective development of auditory sensory epithelium due to connexion dysfunction. Surprisingly, CX26 deficiency is not compensated for by the closely related connexin CX30, which is abundantly expressed in the same cochlear cells. Here, using two mouse models of CX26-associated deafness, we demonstrate that disruption of the CX26-dependent gap junction plaque (GJP) is the earliest observable change during embryonic development of mice with connexin-associated deafness. Loss of CX26 resulted in a drastic reduction in the GJP area and protein level and was associated with excessive endocytosis with increased expression of caveolin 1 and caveolin 2. Furthermore, expression of deafness-associated CX26 and CX30 in cell culture resulted in visible disruption of GJPs and loss of function. Our results demonstrate that deafness-associated mutations in CX26 induce the macromolecular degradation of large gap junction complexes accompanied by an increase in caveolar structures.
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46
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Koval M, Molina SA, Burt JM. Mix and match: investigating heteromeric and heterotypic gap junction channels in model systems and native tissues. FEBS Lett 2014; 588:1193-204. [PMID: 24561196 DOI: 10.1016/j.febslet.2014.02.025] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 02/12/2014] [Accepted: 02/13/2014] [Indexed: 12/12/2022]
Abstract
This review is based in part on a roundtable discussion session: "Physiological roles for heterotypic/heteromeric channels" at the 2013 International Gap Junction Conference (IGJC 2013) in Charleston, South Carolina. It is well recognized that multiple connexins can specifically co-assemble to form mixed gap junction channels with unique properties as a means to regulate intercellular communication. Compatibility determinants for both heteromeric and heterotypic gap junction channel formation have been identified and associated with specific connexin amino acid motifs. Hetero-oligomerization is also a regulated process; differences in connexin quality control and monomer stability are likely to play integral roles to control interactions between compatible connexins. Gap junctions in oligodendrocyte:astrocyte communication and in the cardiovascular system have emerged as key systems where heterotypic and heteromeric channels have unique physiologic roles. There are several methodologies to study heteromeric and heterotypic channels that are best applied to either heterologous expression systems, native tissues or both. There remains a need to use and develop different experimental approaches in order to understand the prevalence and roles for mixed gap junction channels in human physiology.
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Affiliation(s)
- Michael Koval
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, Emory University, Atlanta, GA, United States; Department of Cell Biology, Emory University, Atlanta, GA, United States.
| | - Samuel A Molina
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, Emory University, Atlanta, GA, United States
| | - Janis M Burt
- Department of Physiology, University of Arizona, Tucson, AZ, United States
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47
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Hansen DB, Braunstein TH, Nielsen MS, MacAulay N. Distinct permeation profiles of the connexin 30 and 43 hemichannels. FEBS Lett 2014; 588:1446-57. [PMID: 24503060 DOI: 10.1016/j.febslet.2014.01.036] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 01/23/2014] [Accepted: 01/24/2014] [Indexed: 01/10/2023]
Abstract
Connexin 43 (Cx43) hemichannels may form open channels in the plasma membrane when exposed to specific stimuli, e.g. reduced extracellular concentration of divalent cations, and allow passage of fluorescent molecules and presumably a range of smaller physiologically relevant molecules. However, the permeability profile of Cx43 hemichannels remains unresolved. Exposure of Cx43-expressing Xenopus laevis oocytes to divalent cation free solution induced a gadolinium-sensitive uptake of the fluorescent dye ethidium. In spite thereof, a range of biological molecules smaller than ethidium, such as glutamate, lactate, and glucose, did not permeate the pore whereas ATP did. In contrast, permeability of glutamate, glucose and ATP was observed in oocytes expressing Cx30. Exposure to divalent cation free solutions induced a robust membrane conductance in Cx30-expressing oocytes but none in Cx43-expressing oocytes. C-terminally truncated Cx43 (M257) displayed increased dye uptake and, unlike wild type Cx43 channels, conducted current. Neither Cx30 nor Cx43 acted as water channels in their hemichannel configuration. Our results demonstrate that connexin hemichannels have isoform-specific permeability profiles and that dye uptake cannot be equaled to permeability of smaller physiologically relevant molecules in given settings.
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Affiliation(s)
- Daniel Bloch Hansen
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Thomas Hartig Braunstein
- Danish National Research Foundation Centre for Cardiac Arrhythmia and Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Morten Schak Nielsen
- Danish National Research Foundation Centre for Cardiac Arrhythmia and Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Nanna MacAulay
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
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48
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Yu Q, Wang Y, Chang Q, Wang J, Gong S, Li H, Lin X. Virally expressed connexin26 restores gap junction function in the cochlea of conditional Gjb2 knockout mice. Gene Ther 2013; 21:71-80. [PMID: 24225640 PMCID: PMC3881370 DOI: 10.1038/gt.2013.59] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 09/09/2013] [Accepted: 09/23/2013] [Indexed: 02/03/2023]
Abstract
Mutations in GJB2, which codes for the gap junction protein connexin26, are the most common causes of human nonsyndromic hereditary deafness. We inoculated modified adeno-associated viral vectors into the scala media of early postnatal conditional Gjb2 knockout mice to drive exogenous connexin26 expression. We found extensive virally-expressed connexin26 in cells lining the scala media, and intercellular gap junction network was re-established in the organ of Corti of mutant mouse cochlea. Widespread ectopic connexin26 expression neither formed ectopic gap junctions nor affected normal hearing thresholds in wild type mice, suggesting that autonomous cellular mechanisms regulate proper membrane trafficking of exogenously-expressed connexin26 and govern the functional manifestation of them. Functional recovery of gap-junction-mediated coupling among the supporting cells was observed. We found that both cell death in the organ of Corti and degeneration of spiral ganglion neurons in the cochlea of mutant mice were substantially reduced, although auditory brainstem responses did not show significant hearing improvement. This is the first report demonstrating that virally-mediated gene therapy restored extensive gap junction intercellular network among cochlear non-sensory cells in vivo. Such a treatment performed at early postnatal stages resulted in a partial rescue of disease phenotypes in the cochlea of the mutant mice.
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Affiliation(s)
- Q Yu
- 1] Department of Otolaryngology Head & Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing, China [2] Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, USA
| | - Y Wang
- Department of Otolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China
| | - Q Chang
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, USA
| | - J Wang
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, USA
| | - S Gong
- Department of Otolaryngology Head & Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - H Li
- Department of Otolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China
| | - X Lin
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, USA
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49
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Protection of spiral ganglion neurons from degeneration using small-molecule TrkB receptor agonists. J Neurosci 2013; 33:13042-52. [PMID: 23926258 DOI: 10.1523/jneurosci.0854-13.2013] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neurotrophins (NTs) play essential roles in the development and survival of neurons in PNS and CNS. In the cochlea, NTs [e.g., NT-3, brain-derived neurotrophic factor (BDNF)] are required for the survival of spiral ganglion neurons (SGNs). Preservation of SGNs in the cochlea of patients suffering sensorineural deafness caused by loss of hair cells is needed for the optimal performance of the cochlear implant. Directly applying exogenous BDNF into the cochlea prevents secondary degeneration of SGNs when hair cells are lost. However, a common translational barrier for in vivo applications of BDNF is the poor pharmacokinetics, which severely limits the efficacy. Here we report that 7,8-dihydroxyflavone and 7,8,3'-trihydroxyflavone, both small-molecule agonists of tyrosine receptor kinase B (TrkB), promoted SGN survival with high potency both in vitro and in vivo. These compounds increased the phosphorylated TrkB and downstream MAPK and protected the SGNs in a TrkB-dependent manner. Their applications in the bulla of conditional connexin26 null mice offered significant protection for SGN survival. The function of survived SGNs was assessed by measuring evoked action potentials (APs) in vitro and electrically evoked auditory brainstem response (eABR) thresholds in vivo. APs were reliably evoked in cultured single SGNs treated with the compounds. In addition, eABR thresholds measured from the treated cochleae were significantly lower than untreated controls. Our findings suggest that these novel small-molecule TrkB agonists are promising in vivo therapeutic agents for preventing degeneration of SGNs.
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50
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Jagger DJ, Forge A. The enigmatic root cell – Emerging roles contributing to fluid homeostasis within the cochlear outer sulcus. Hear Res 2013; 303:1-11. [DOI: 10.1016/j.heares.2012.10.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 10/19/2012] [Accepted: 10/26/2012] [Indexed: 12/20/2022]
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