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Domínguez-Ruiz M, Murillo-Cuesta S, Contreras J, Cantero M, Garrido G, Martín-Bernardo B, Gómez-Rosas E, Fernández A, Del Castillo FJ, Montoliu L, Varela-Nieto I, Del Castillo I. A murine model for the del(GJB6-D13S1830) deletion recapitulating the phenotype of human DFNB1 hearing impairment: generation and functional and histopathological study. BMC Genomics 2024; 25:359. [PMID: 38605287 PMCID: PMC11007912 DOI: 10.1186/s12864-024-10289-z] [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: 02/06/2024] [Accepted: 04/07/2024] [Indexed: 04/13/2024] Open
Abstract
Inherited hearing impairment is a remarkably heterogeneous monogenic condition, involving hundreds of genes, most of them with very small (< 1%) epidemiological contributions. The exception is GJB2, the gene encoding connexin-26 and underlying DFNB1, which is the most frequent type of autosomal recessive non-syndromic hearing impairment (ARNSHI) in most populations (up to 40% of ARNSHI cases). DFNB1 is caused by different types of pathogenic variants in GJB2, but also by large deletions that keep the gene intact but remove an upstream regulatory element that is essential for its expression. Such large deletions, found in most populations, behave as complete loss-of-function variants, usually associated with a profound hearing impairment. By using CRISPR-Cas9 genetic edition, we have generated a murine model (Dfnb1em274) that reproduces the most frequent of those deletions, del(GJB6-D13S1830). Dfnb1em274 homozygous mice are viable, bypassing the embryonic lethality of the Gjb2 knockout, and present a phenotype of profound hearing loss (> 90 dB SPL) that correlates with specific structural abnormalities in the cochlea. We show that Gjb2 expression is nearly abolished and its protein product, Cx26, is nearly absent all throughout the cochlea, unlike previous conditional knockouts in which Gjb2 ablation was not obtained in all cell types. The Dfnb1em274 model recapitulates the clinical presentation of patients harbouring the del(GJB6-D13S1830) variant and thus it is a valuable tool to study the pathological mechanisms of DFNB1 and to assay therapies for this most frequent type of human ARNSHI.
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Affiliation(s)
- María Domínguez-Ruiz
- Servicio de Genética, Hospital Universitario Ramón y Cajal, IRYCIS, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain
| | - Silvia Murillo-Cuesta
- Institute for Biomedical Research "Sols-Morreale", Spanish National Research Council-Autonomous University of Madrid, Madrid, Spain
- Hospital La Paz Institute for Health Research (IdiPAZ), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain
| | - Julio Contreras
- Institute for Biomedical Research "Sols-Morreale", Spanish National Research Council-Autonomous University of Madrid, Madrid, Spain
- Anatomy and Embryology Department, Faculty of Veterinary, Universidad Complutense de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain
| | - Marta Cantero
- Department of Molecular and Cellular Biology, National Centre for Biotechnology (CNB-CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain
| | - Gema Garrido
- Servicio de Genética, Hospital Universitario Ramón y Cajal, IRYCIS, Madrid, Spain
- Department of Molecular and Cellular Biology, National Centre for Biotechnology (CNB-CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain
| | - Belén Martín-Bernardo
- Institute for Biomedical Research "Sols-Morreale", Spanish National Research Council-Autonomous University of Madrid, Madrid, Spain
- Hospital La Paz Institute for Health Research (IdiPAZ), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain
| | - Elena Gómez-Rosas
- Servicio de Genética, Hospital Universitario Ramón y Cajal, IRYCIS, Madrid, Spain
| | - Almudena Fernández
- Department of Molecular and Cellular Biology, National Centre for Biotechnology (CNB-CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain
| | - Francisco J Del Castillo
- Servicio de Genética, Hospital Universitario Ramón y Cajal, IRYCIS, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain
| | - Lluís Montoliu
- Department of Molecular and Cellular Biology, National Centre for Biotechnology (CNB-CSIC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain
| | - Isabel Varela-Nieto
- Institute for Biomedical Research "Sols-Morreale", Spanish National Research Council-Autonomous University of Madrid, Madrid, Spain
- Hospital La Paz Institute for Health Research (IdiPAZ), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain
| | - Ignacio Del Castillo
- Servicio de Genética, Hospital Universitario Ramón y Cajal, IRYCIS, Madrid, Spain.
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain.
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Qiu Y, Xie L, Wang X, Xu K, Bai X, Chen S, Sun Y. Abnormal Innervation, Demyelination, and Degeneration of Spiral Ganglion Neurons as Well as Disruption of Heminodes are Involved in the Onset of Deafness in Cx26 Null Mice. Neurosci Bull 2024:10.1007/s12264-023-01167-x. [PMID: 38311706 DOI: 10.1007/s12264-023-01167-x] [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: 07/08/2023] [Accepted: 09/14/2023] [Indexed: 02/06/2024] Open
Abstract
GJB2 gene mutations are the most common causes of autosomal recessive non-syndromic hereditary deafness. For individuals suffering from severe to profound GJB2-related deafness, cochlear implants have emerged as the sole remedy for auditory improvement. Some previous studies have highlighted the crucial role of preserving cochlear neural components in achieving favorable outcomes after cochlear implantation. Thus, we generated a conditional knockout mouse model (Cx26-CKO) in which Cx26 was completely deleted in the cochlear supporting cells driven by the Sox2 promoter. The Cx26-CKO mice showed severe hearing loss and massive loss of hair cells and Deiter's cells, which represented the extreme form of human deafness caused by GJB2 gene mutations. In addition, multiple pathological changes in the peripheral auditory nervous system were found, including abnormal innervation, demyelination, and degeneration of spiral ganglion neurons as well as disruption of heminodes in Cx26-CKO mice. These findings provide invaluable insights into the deafness mechanism and the treatment for severe deafness in Cx26-null mice.
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Affiliation(s)
- Yue Qiu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Le Xie
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Xiaohui Wang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Kai Xu
- Department of Otolaryngology, Nanchang University, Nanchang, 330006, China
| | - Xue Bai
- Department of Otolaryngology, Nanchang University, Nanchang, 330006, China
| | - Sen Chen
- 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.
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Xu K, Chen S, Bai X, Xie L, Qiu Y, Liu X, Wang X, Kong W, Sun Y. Degradation of cochlear Connexin26 accelerate the development of age-related hearing loss. Aging Cell 2023; 22:e13973. [PMID: 37681746 PMCID: PMC10652327 DOI: 10.1111/acel.13973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 08/03/2023] [Accepted: 08/15/2023] [Indexed: 09/09/2023] Open
Abstract
The GJB2 gene, encoding Connexin26 (Cx26), is one of the most common causes of inherited deafness. Clinically, mutations in GJB2 cause congenital deafness or late-onset progressive hearing loss. Recently, it has been reported that Cx26 haploid deficiency accelerates the development of age-related hearing loss (ARHL). However, the roles of cochlear Cx26 in the hearing function of aged animals remain unclear. In this study, we revealed that the Cx26 expression was significantly reduced in the cochleae of aged mice, and further explored the underlying molecular mechanism for Cx26 degradation. Immunofluorescence co-localization results showed that Cx26 was internalized and degraded by lysosomes, which might be one of the important ways for Cx26 degradation in the cochlea of aged mice. Currently, whether the degradation of Cx26 in the cochlea leads directly to ARHL, as well as the mechanism of Cx26 degradation-related hearing loss are still unclear. To address these questions, we generated mice with Cx26 knockout in the adult cochlea as a model for the natural degradation of Cx26. Auditory brainstem response (ABR) results showed that Cx26 knockout mice exhibited high-frequency hearing loss, which gradually progressed over time. Pathological examination also revealed the degeneration of hair cells and spiral ganglions, which is similar to the phenotype of ARHL. In summary, our findings suggest that degradation of Cx26 in the cochlea accelerates the occurrence of ARHL, which may be a novel mechanism of ARHL.
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Affiliation(s)
- Kai Xu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
| | - Sen Chen
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
| | - Xue Bai
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
| | - Le Xie
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
| | - Yue Qiu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
| | - Xiao‐zhou Liu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
| | - Xiao‐hui Wang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
| | - Wei‐jia Kong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
- Hubei Province Key Laboratory of Oral and Maxillofacial Development and RegenerationWuhanChina
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Li Q, Cui C, Liao R, Yin X, Wang D, Cheng Y, Huang B, Wang L, Yan M, Zhou J, Zhao J, Tang W, Wang Y, Wang X, Lv J, Li J, Li H, Shu Y. The pathogenesis of common Gjb2 mutations associated with human hereditary deafness in mice. Cell Mol Life Sci 2023; 80:148. [PMID: 37178259 PMCID: PMC10182940 DOI: 10.1007/s00018-023-04794-9] [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: 12/27/2022] [Revised: 03/31/2023] [Accepted: 04/28/2023] [Indexed: 05/15/2023]
Abstract
Mutations in GJB2 (Gap junction protein beta 2) are the most common genetic cause of non-syndromic hereditary deafness in humans, especially the 35delG and 235delC mutations. Owing to the homozygous lethality of Gjb2 mutations in mice, there are currently no perfect mouse models carrying Gjb2 mutations derived from patients for mimicking human hereditary deafness and for unveiling the pathogenesis of the disease. Here, we successfully constructed heterozygous Gjb2+/35delG and Gjb2+/235delC mutant mice through advanced androgenic haploid embryonic stem cell (AG-haESC)-mediated semi-cloning technology, and these mice showed normal hearing at postnatal day (P) 28. A homozygous mutant mouse model, Gjb235delG/35delG, was then generated using enhanced tetraploid embryo complementation, demonstrating that GJB2 plays an indispensable role in mouse placenta development. These mice exhibited profound hearing loss similar to human patients at P14, i.e., soon after the onset of hearing. Mechanistic analyses showed that Gjb2 35delG disrupts the function and formation of intercellular gap junction channels of the cochlea rather than affecting the survival and function of hair cells. Collectively, our study provides ideal mouse models for understanding the pathogenic mechanism of DFNB1A-related hereditary deafness and opens up a new avenue for investigating the treatment of this disease.
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Affiliation(s)
- Qing Li
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China.
| | - Chong Cui
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Rongyu Liao
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Xidi Yin
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Daqi Wang
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Yanbo Cheng
- School of Life Science and Technology, Shanghai Tech University, Shanghai, China
| | - Bowei Huang
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Liqin Wang
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Meng Yan
- School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China
| | - Jinan Zhou
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Jingjing Zhao
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Wei Tang
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Yingyi Wang
- School of Life Science and Technology, Shanghai Tech University, Shanghai, China
| | | | - Jun Lv
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Jinsong Li
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
- School of Life Science and Technology, Shanghai Tech University, Shanghai, China
- School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China
| | - Huawei Li
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China.
- Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China.
| | - Yilai Shu
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China.
- Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China.
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The protective effects of systemic dexamethasone on sensory epithelial damage and hearing loss in targeted Cx26-null mice. Cell Death Dis 2022; 13:545. [PMID: 35688810 PMCID: PMC9187686 DOI: 10.1038/s41419-022-04987-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 05/25/2022] [Accepted: 05/30/2022] [Indexed: 01/21/2023]
Abstract
Mutations in the GJB2 gene (encoding Connexin26(Cx26)) are the most common cause of hereditary deafness, accounting for about a quarter of all cases. Sensory epithelial damage is considered to be one of the main causes of deafness caused by GJB2 gene mutation. Dexamethasone (DEX) is widely used in the treatment of a variety of inner ear diseases including sudden sensorineural hearing loss (SSNHL), noise-induced hearing loss (NIHL), and deafness caused by ototoxic drugs. Whether DEX has a direct therapeutic effect on hereditary deafness, especially GJB2-related deafness, remains unclear. In this study, we revealed that DEX can effectively prevent hair cell death caused by oxidative stress in cochlear explants. Additionally, two distinct Cx26-null mouse models were established to investigate whether systemic administration of DEX alleviate the cochlear sensory epithelial injury or deafness in these models. In a specific longitudinally Cx26-null model that does not cause deafness, systemic administration of DEX prevents the degeneration of outer hair cells (OHCs) induced by Cx26 knockout. Similarly, in a targeted-Deiter's cells (DCs) Cx26-null mouse model that causes deafness, treatment with DEX can almost completely prevent OHCs loss and alleviates auditory threshold shifts at some frequencies. Additionally, we observed that DEX inhibited the recruitment of CD45-positive cells in the targeted-DCs Cx26-null mice. Taken together, our results suggest that the protective effect of dexamethasone on cochlear sensory epithelial damage and partially rescue auditory function may be related to the regulation of inner ear immune response in Cx26 deficiency mouse models.
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Connexin Mutations and Hereditary Diseases. Int J Mol Sci 2022; 23:ijms23084255. [PMID: 35457072 PMCID: PMC9027513 DOI: 10.3390/ijms23084255] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 04/04/2022] [Accepted: 04/09/2022] [Indexed: 02/01/2023] Open
Abstract
Inherited diseases caused by connexin mutations are found in multiple organs and include hereditary deafness, congenital cataract, congenital heart diseases, hereditary skin diseases, and X-linked Charcot–Marie–Tooth disease (CMT1X). A large number of knockout and knock-in animal models have been used to study the pathology and pathogenesis of diseases of different organs. Because the structures of different connexins are highly homologous and the functions of gap junctions formed by these connexins are similar, connexin-related hereditary diseases may share the same pathogenic mechanism. Here, we analyze the similarities and differences of the pathology and pathogenesis in animal models and find that connexin mutations in gap junction genes expressed in the ear, eye, heart, skin, and peripheral nerves can affect cellular proliferation and differentiation of corresponding organs. Additionally, some dominant mutations (e.g., Cx43 p.Gly60Ser, Cx32 p.Arg75Trp, Cx32 p.Asn175Asp, and Cx32 p.Arg142Trp) are identified as gain-of-function variants in vivo, which may play a vital role in the onset of dominant inherited diseases. Specifically, patients with these dominant mutations receive no benefits from gene therapy. Finally, the complete loss of gap junctional function or altered channel function including permeability (ions, adenosine triphosphate (ATP), Inositol 1,4,5-trisphosphate (IP3), Ca2+, glucose, miRNA) and electric activity are also identified in vivo or in vitro.
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Liu XZ, Jin Y, Chen S, Xu K, Xie L, Qiu Y, Wang XH, Sun Y, Kong WJ. F-Actin Dysplasia Involved in Organ of Corti Deformity in Gjb2 Knockdown Mouse Model. Front Mol Neurosci 2022; 14:808553. [PMID: 35345836 PMCID: PMC8957075 DOI: 10.3389/fnmol.2021.808553] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 12/13/2021] [Indexed: 11/13/2022] Open
Abstract
Mutations in the GJB2 gene encoding connexin26 (Cx26) protein are one of the most common causes of hereditary deafness. Previous studies have found that different Cx26-null mouse models have severe hearing loss and deformity of the organ of Corti (OC) as well as a reduction in microtubules in pillar cells (PCs). To explore the underlying mechanism of OC deformity caused by Cx26 downregulation further, we established Cx26 knockdown (KD) mouse models at postnatal days (P)0 and P8. The actin filaments contained in the pillar cells of mice in the P0 KD group were reduced by 54.85% and vinculin was increased by 22%, while the outer hair cells (OHCs) showed normal F-actin content. In the P8 KD group, PCs and OHCs of mice also showed almost normal F-actin content. The G-actin/F-actin ratio increased by 38% in the P0 KD group. No significant change was found in the mRNA or protein expression level of G-actin or the cadherin–catenin core complex in the P0 KD group at P6. Moreover, immunofluorescence showed that the intensity of LRRK2 was reduced by 97% in the P0 KD group at P6. Our results indicate that Cx26 is involved in the maturation of the cytoskeleton during the development of the OC at the early postnatal stage. The polymerization of G-actin into F-actin is prevented in Cx26 KD mice.
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Affiliation(s)
- Xiao-zhou Liu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yuan Jin
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Sen Chen
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Kai Xu
- Department of Otolaryngology, Head and Neck Surgery, The Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Le Xie
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yue Qiu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiao-hui Wang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- *Correspondence: Yu Sun Wei-jia Kong
| | - Wei-jia Kong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- *Correspondence: Yu Sun Wei-jia Kong
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Morell M, Rojas L, Haulena M, Busse B, Siebert U, Shadwick RE, Raverty SA. Selective Inner Hair Cell Loss in a Neonate Harbor Seal (Phoca vitulina). Animals (Basel) 2022; 12:ani12020180. [PMID: 35049802 PMCID: PMC8772928 DOI: 10.3390/ani12020180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/06/2022] [Accepted: 01/07/2022] [Indexed: 01/19/2023] Open
Abstract
Simple Summary Congenital hearing loss (i.e., hearing impairment present at birth) is recognized in humans and other terrestrial species, but there is a lack of information on congenital malformations and associated hearing loss in pinnipeds (seals, sea lions, and walruses). Baseline knowledge on marine mammal inner ear malformations is essential to differentiate between congenital and acquired abnormalities, which may be caused by infectious agents, age, or anthropogenic interactions, such as noise exposure. Analysis of the cochlea of a neonate harbor seal (Phoca vitulina) revealed bilateral loss of inner hair cells (sensory cells responsible for transducing the auditory signal) while the outer hair cells (sensory cells responsible for sound amplification and frequency selectivity and sensitivity) were intact. The selective inner hair cell loss (up to 84.6% of loss) was more severe in the basal turn, where the high frequencies are encoded. Potential causes and consequences are discussed. This is the first report of a case of selective inner hair cell loss in a marine mammal neonate, likely congenital. Abstract Congenital hearing loss is recognized in humans and other terrestrial species. However, there is a lack of information on its prevalence or pathophysiology in pinnipeds. It is important to have baseline knowledge on marine mammal malformations in the inner ear, to differentiate between congenital and acquired abnormalities, which may be caused by infectious pathogens, age, or anthropogenic interactions, such as noise exposure. Ultrastructural evaluation of the cochlea of a neonate harbor seal (Phoca vitulina) by scanning electron microscopy revealed bilateral loss of inner hair cells with intact outer hair cells. The selective inner hair cell loss was more severe in the basal turn, where high-frequency sounds are encoded. The loss of inner hair cells started around 40% away from the apex or tip of the spiral, reaching a maximum loss of 84.6% of hair cells at 80–85% of the length from the apex. Potential etiologies and consequences are discussed. This is believed to be the first case report of selective inner hair cell loss in a marine mammal neonate, likely congenital.
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Affiliation(s)
- Maria Morell
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, 25761 Büsum, Germany;
- Zoology Department, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
- Correspondence:
| | - Laura Rojas
- Faculty of Veterinary Medicine and Zootechnics, National Autonomous University of Mexico, Av. Universidad 3000, Delegación Coyoacán, Mexico City 04510, Mexico;
| | - Martin Haulena
- Vancouver Aquarium Marine Science Center, Vancouver, BC V6G 3E2, Canada;
| | - Björn Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 22529 Hamburg, Germany;
| | - Ursula Siebert
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, 25761 Büsum, Germany;
| | - Robert E. Shadwick
- Zoology Department, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
| | - Stephen A. Raverty
- Zoology Department, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
- Animal Health Center, Ministry of Agriculture, Abbotsford, BC V3G 2M3, Canada;
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Xu K, Chen S, Xie L, Qiu Y, Bai X, Liu XZ, Zhang HM, Wang XH, Jin Y, Sun Y, Kong WJ. Local Macrophage-Related Immune Response Is Involved in Cochlear Epithelial Damage in Distinct Gjb2-Related Hereditary Deafness Models. Front Cell Dev Biol 2021; 8:597769. [PMID: 33505961 PMCID: PMC7829512 DOI: 10.3389/fcell.2020.597769] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 12/07/2020] [Indexed: 12/31/2022] Open
Abstract
The macrophage-related immune response is an important component of the cochlear response to different exogenous stresses, including noise, ototoxic antibiotics, toxins, or viral infection. However, the role of the immune response in hereditary deafness caused by genetic mutations is rarely explored. GJB2, encoding connexin 26 (Cx26), is the most common deafness gene of hereditary deafness. In this study, two distinct Cx26-null mouse models were established to investigate the types and underlying mechanisms of immune responses. In a systemic Cx26-null model, macrophage recruitment was observed, associated with extensive cell degeneration of the cochlear epithelium. In a targeted-cell Cx26-null model, knockout of Cx26 was restricted to specific supporting cells (SCs), which led to preferential loss of local outer hair cells (OHCs). This local OHC loss can also induce a macrophage-related immune response. Common inflammatory factors, including TNF-α, IL-1β, Icam-1, Mif, Cx3cr1, Tlr4, Ccl2, and Ccr2, did not change significantly, while mRNA of Cx3cl1 was upregulated. Quantitative immunofluorescence showed that the protein expression of CX3CL1 in Deiters cells, a type of SC coupled with OHCs, increased significantly after OHC death. OHC loss caused the secondary death of spiral ganglion neurons (SGNs), while the remaining SGNs expressed high levels of CX3CL1 with infiltrated macrophages. Taken together, our results indicate that CX3CL1 signaling regulates macrophage recruitment and that enhancement of macrophage antigen-presenting function is associated with cell degeneration in Cx26-null mice.
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Affiliation(s)
- Kai Xu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Sen Chen
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Le Xie
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yue Qiu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xue Bai
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiao-Zhou Liu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hui-Min Zhang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiao-Hui Wang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yuan Jin
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei-Jia Kong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Tongji Medical College, Institute of Otorhinolaryngology, Huazhong University of Science and Technology, Wuhan, China
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10
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Wu H, Sun H, He Z, Chen X, Li Y, Zhao X, Kong W, Kong W. The effect and mechanism of 19S proteasome PSMD11/Rpn6 subunit in D-Galactose induced mimetic aging models. Exp Cell Res 2020; 394:112093. [PMID: 32450067 DOI: 10.1016/j.yexcr.2020.112093] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 05/14/2020] [Accepted: 05/16/2020] [Indexed: 11/30/2022]
Abstract
Regulating proteasome activity is a potent therapeutic aspect of age-related hearing loss, which has been proven to protect neurons from age-related damaging. PSMD11, subunit of the 19S proteasome regulatory particle, is known to mainly up-regulate proteasome activity and prolong aging. However, the mechanism of PSMD11 in age-related hearing loss has not been deeply explored. In the present study, we explore the function and mechanism of PSMD11 protecting neurons in d-Galactose (D-Gal) mimetic aging models. Age-related pathologies were detected by Taq-PCR, ABR, Transmission electron microscopy, toluidine blue and β-galactosidase staining. The relative expressions of the proteins were explored by Western blotting, oxyblot, immunoprecipitation and immunofluorescence. Flow cytometry was used to manifest the oxidative state. We discovered that proteasome activity was impaired with aging, and that ROS and toxic protein accumulated in D-Gal induced aging models. PSMD11 changed with aging, and was associated with the metabolism of proteasome activity in the D-Gal treated models. Moreover, the knockdown or overexpression of PSMD11 was sufficient to change the oxidative state caused by D-Gal. Our results also demonstrated that PSMD11 could bond to AMPKα1/2 in the auditory cortex and PC12 cells, and AMPKα2 but not AMPKα1 was efficient to regulate the function of PSMD11. Deeper insights into the mechanisms of regulating PSMD11 for the anti-aging process are needed, and may offer novel therapeutic methods for central presbycusis.
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Affiliation(s)
- Han Wu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| | - Haiying Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| | - Zuhong He
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| | - Xi Chen
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| | - Yongqin Li
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| | - Xueyan Zhao
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| | - Wen Kong
- Departments of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430022, China.
| | - Weijia Kong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
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11
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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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12
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Advances in cochlear implantation for hereditary deafness caused by common mutations in deafness genes. JOURNAL OF BIO-X RESEARCH 2019. [DOI: 10.1097/jbr.0000000000000037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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13
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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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14
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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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15
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Delmar M, Laird DW, Naus CC, Nielsen MS, Verselis VK, White TW. Connexins and Disease. Cold Spring Harb Perspect Biol 2018; 10:cshperspect.a029348. [PMID: 28778872 DOI: 10.1101/cshperspect.a029348] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Inherited or acquired alterations in the structure and function of connexin proteins have long been associated with disease. In the present work, we review current knowledge on the role of connexins in diseases associated with the heart, nervous system, cochlea, and skin, as well as cancer and pleiotropic syndromes such as oculodentodigital dysplasia (ODDD). Although incomplete by virtue of space and the extent of the topic, this review emphasizes the fact that connexin function is not only associated with gap junction channel formation. As such, both canonical and noncanonical functions of connexins are fundamental components in the pathophysiology of multiple connexin related disorders, many of them highly debilitating and life threatening. Improved understanding of connexin biology has the potential to advance our understanding of mechanisms, diagnosis, and treatment of disease.
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Affiliation(s)
- Mario Delmar
- The Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York 10016
| | - Dale W Laird
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario N6A5C1, Canada
| | - Christian C Naus
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Morten S Nielsen
- Department of Biological Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Vytautas K Verselis
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, New York 10461
| | - Thomas W White
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York 11790
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16
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Chen S, Xie L, Xu K, Cao HY, Wu X, Xu XX, Sun Y, Kong WJ. Developmental abnormalities in supporting cell phalangeal processes and cytoskeleton in the Gjb2 knockdown mouse model. Dis Model Mech 2018; 11:dmm.033019. [PMID: 29361521 PMCID: PMC5894950 DOI: 10.1242/dmm.033019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 01/15/2018] [Indexed: 12/30/2022] Open
Abstract
Mutations in the GJB2 gene [which encodes connexin 26 (Cx26)] are the most common causes of hereditary hearing loss in humans, and previous studies showed postnatal development arrest of the organ of Corti in different Cx26-null mouse models. To explore the pathological changes and the mechanism behind the cochlear abnormalities in these mice further, we established transgenic mouse models by conditional knockdown of cochlear Cx26 at postnatal day (P) 0 and P8. Auditory brainstem responses were recorded and the morphological features in the organ of Corti were analyzed 18 days after Cx26 knockdown. Mice in the P0 knockdown group displayed severe hearing loss at all frequencies, whereas mice in the P8 knockdown group showed nearly normal hearing. In the P8 knockdown group, the organ of Corti displayed normal architecture, and no ultrastructural changes were observed. In the P0 knockdown group, the phalangeal processes of Deiter's cells did not develop into finger-like structures, and the formation of microtubules in the pillar cells was significantly reduced; moreover, the amount of acetylated α-tubulin was reduced in pillar cells. Our results indicate that Gjb2 participates in postnatal development of the cytoskeleton in pillar cells during structural maturation of the organ of Corti. In P0 knockdown mice, the reduction in microtubules in pillar cells might be responsible for the failure of the tunnel of Corti to open, and the malformed phalangeal processes might negatively affect the supporting framework of the organ of Corti, which would be a new mechanism of Gjb2-related hearing loss. Summary: A reduction in connexin 26 before opening of the tunnel of Corti impedes microtubule formation in supporting cells, and this may lead to cochlear developmental abnormalities and deafness in the Gjb2 knockdown mouse model.
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Affiliation(s)
- Sen Chen
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Le Xie
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Kai Xu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Hai-Yan Cao
- Department of Ultrasound, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xia Wu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xiao-Xiang Xu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China .,Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Wei-Jia Kong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China .,Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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17
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Lin J, Huang H, Lv G, Xu X, Lin W, Xu X, Cheng J, Zheng M. Chronic prenatal hypoxia impairs cochlear development, a mechanism involving connexin26 expression and promoter methylation. Int J Mol Med 2017; 41:852-858. [PMID: 29207085 PMCID: PMC5752184 DOI: 10.3892/ijmm.2017.3303] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 11/02/2017] [Indexed: 12/31/2022] Open
Abstract
Chronic prenatal hypoxia is a damaging to fetal development and may have various consequences, including hearing loss. Connexin 26 (Cx26) is one of the major protein subunits required for gap junction formation, and has an important role in maintaining homeostasis in the cochlea and normal hearing. Cx26 mutation and expression abnormality are closely associated with inherited nonsyndromic deafness, but the association between Cx26 and prenatal hypoxia is less established. The present study aimed to examine Cx26 expression and aberrant methylation the Cx26 promoter region in the cochlea from rats exposed to chronic prenatal hypoxia. Hematoxylin and eosin staining demonstrated that the number of hair cells in the organ of Corti were less in the hypoxia group. Reverse transcription-quantitative polymerase chain reaction and western blot analysis revealed that protein and mRNA levels of Cx26 were decreased in the hypoxia group compared with the control group. Further bisulfite sequencing analysis revealed that prenatal hypoxia significantly increased the methylation status of the promoter region of the Cx26 gene. These results demonstrate that chronic prenatal hypoxia caused hearing impairment, and suggest that promoter region hypermethylation and expression downregulation of Cx26 underlie the mechanism of action.
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Affiliation(s)
- Jingcang Lin
- Department of Anatomy, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, Fujian 350004, P.R. China
| | - Huang Huang
- Department of Histology and Embryology, Quanzhou Medical College, Quanzhou, Fujian 362100, P.R. China
| | - Guorong Lv
- Department of Medical Imaging, Quanzhou Medical College, Quanzhou, Fujian 362100, P.R. China
| | - Xiangyang Xu
- Department of Histology and Embryology, Quanzhou Medical College, Quanzhou, Fujian 362100, P.R. China
| | - Wendong Lin
- Department of Anatomy, Quanzhou Medical College, Quanzhou, Fujian 362100, P.R. China
| | - Xianyan Xu
- Department of Anatomy, Quanzhou Medical College, Quanzhou, Fujian 362100, P.R. China
| | - Jing Cheng
- Department of Histology and Embryology, Quanzhou Medical College, Quanzhou, Fujian 362100, P.R. China
| | - Ming Zheng
- Department of Anatomy, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, Fujian 350004, P.R. China
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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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19
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Deformation of the Outer Hair Cells and the Accumulation of Caveolin-2 in Connexin 26 Deficient Mice. PLoS One 2015; 10:e0141258. [PMID: 26492081 PMCID: PMC4619622 DOI: 10.1371/journal.pone.0141258] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 10/06/2015] [Indexed: 11/23/2022] Open
Abstract
Background Mutations in GJB2, which encodes connexin 26 (Cx26), a cochlear gap junction protein, represent a major cause of pre-lingual, non-syndromic deafness. The degeneration of the organ of Corti observed in Cx26 mutant—associated deafness is thought to be a secondary pathology of hearing loss. Here we focused on abnormal development of the organ of Corti followed by degeneration including outer hair cell (OHC) loss. Methods We investigated the crucial factors involved in late-onset degeneration and loss of OHC by ultrastructural observation, immunohistochemistry and protein analysis in our Cx26-deficient mice (Cx26f/fP0Cre). Results In ultrastructural observations of Cx26f/fP0Cre mice, OHCs changed shape irregularly, and several folds or notches were observed in the plasma membrane. Furthermore, the mutant OHCs had a flat surface compared with the characteristic wavy surface structure of OHCs of normal mice. Protein analysis revealed an increased protein level of caveolin-2 (CAV2) in Cx26f/fP0Cre mouse cochlea. In immunohistochemistry, a remarkable accumulation of CAV2 was observed in Cx26f/fP0Cre mice. In particular, this accumulation of CAV2 was mainly observed around OHCs, and furthermore this accumulation was observed around the shrunken site of OHCs with an abnormal hourglass-like shape. Conclusions The deformation of OHCs and the accumulation of CAV2 in the organ of Corti may play a crucial role in the progression of, or secondary OHC loss in, GJB2-associated deafness. Investigation of these molecular pathways, including those involving CAV2, may contribute to the elucidation of a new pathogenic mechanism of GJB2-associated deafness and identify effective targets for new therapies.
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20
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Lee MY, Takada T, Takada Y, Kappy MD, Beyer LA, Swiderski DL, Godin AL, Brewer S, King WM, Raphael Y. Mice with conditional deletion of Cx26 exhibit no vestibular phenotype despite secondary loss of Cx30 in the vestibular end organs. Hear Res 2015; 328:102-12. [PMID: 26232528 DOI: 10.1016/j.heares.2015.07.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 07/22/2015] [Accepted: 07/23/2015] [Indexed: 01/19/2023]
Abstract
Connexins are components of gap junctions which facilitate transfer of small molecules between cells. One member of the connexin family, Connexin 26 (Cx26), is prevalent in gap junctions in sensory epithelia of the inner ear. Mutations of GJB2, the gene encoding Cx26, cause significant hearing loss in humans. The vestibular system, however, does not usually show significant functional deficits in humans with this mutation. Mouse models for loss of Cx26 function demonstrate hearing loss and cochlear pathology but the extent of vestibular dysfunction and organ pathology are less well characterized. To understand the vestibular effects of Cx26 mutations, we evaluated vestibular function and histology of the vestibular sensory epithelia in a conditional knockout (CKO) mouse with Cx26 loss of function. Transgenic C57BL/6 mice, in which cre-Sox10 drives excision of the Cx26 gene from non-sensory cells flanking the sensory epithelium of the inner ear (Gjb2-CKO), were compared to age-matched wild types. Animals were sacrificed at ages between 4 and 40 weeks and their cochlear and vestibular sensory organs harvested for histological examination. Cx26 immunoreactivity was prominent in the peripheral vestibular system and the cochlea of wild type mice, but absent in the Gjb2-CKO specimens. The hair cell population in the cochleae of the Gjb2-CKO mice was severely depleted but in the vestibular organs it was intact, despite absence of Cx26 expression. The vestibular organs appeared normal at the latest time point examined, 40 weeks. To determine whether compensation by another connexin explains survival of the normal vestibular sensory epithelium, we evaluated the presence of Cx30 in the Gjb2-CKO mouse. We found that Cx30 labeling was normal in the cochlea, but it was decreased or absent in the vestibular system. The vestibular phenotype of the mutants was not different from wild-types as determined by time on the rotarod, head stability tests and physiological responses to vestibular stimulation. Thus presence of Cx30 in the cochlea does not compensate for Cx26 loss, and the absence of both connexins from vestibular sensory epithelia is no more injurious than the absence of one of them. Further studies to uncover the physiological foundation for this difference between the cochlea and the vestibular organs may help in designing treatments for GJB2 mutations.
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Affiliation(s)
- Min Young Lee
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Tomoko Takada
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Yohei Takada
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Michelle D Kappy
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Lisa A Beyer
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Donald L Swiderski
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Ashley L Godin
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Shannon Brewer
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - W Michael King
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA
| | - Yehoash Raphael
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, 1150 West. Medical Center Dr., Ann Arbor, MI 48109-5648, USA.
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21
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Wang W, Sun Y, Chen S, Zhou X, Wu X, Kong W, Kong W. Impaired unfolded protein response in the degeneration of cochlea cells in a mouse model of age-related hearing loss. Exp Gerontol 2015; 70:61-70. [PMID: 26173054 DOI: 10.1016/j.exger.2015.07.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 06/03/2015] [Accepted: 07/07/2015] [Indexed: 12/31/2022]
Abstract
Endoplasmic reticulum (ER) stress triggers the unfolded protein response (UPR) to prevent the accumulation of proteins in an aberrant conformation. The UPR can restore homeostasis by upregulating ER chaperones, such as glucose-regulated protein 78kD (GRP78), to refold the incorrectly handled protein, and by degrading the misfolded proteins via the ubiquitin-proteasome and autophagy-lysosome system. ER stress was recently demonstrated to be involved in the pathogenesis of age-related diseases. In this study, we measured the expression levels of GRP78 and ubiquitinated proteins in the cochleae of young C57BL/6 mice and aged mice to assess the capacity of the UPR. The lower expression of GRP78 and the increased number of ubiquitinated proteins observed in the cochleae of aged mice suggested that the capacity of the UPR was impaired and that the cell death pathway was activated. We found a markedly increased expression of the ER-related pro-apoptotic factor C/EBP homologous protein (CHOP) in the cochleae of aged mice, whereas the level of cleaved caspase-12 did not differ between the two groups. In addition, the cleavage of caspase-9, caspase-3 and poly [ADP-ribose] polymerase 1 was significantly increased in the aged cochleae, suggesting the activation of apoptosis in the cochleae resulting from the cross-talk between the ER and mitochondria through CHOP. These results indicated that impaired UPR in the cochleae of aged C57BL/6 mice resulting in ER stress may lead to apoptosis that is dependent on the mitochondrial pathway and that ER stress induced apoptosis may not be mediated by caspase-12.
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Affiliation(s)
- Wenwen Wang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China
| | - Sen Chen
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China
| | - Xingxing Zhou
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China
| | - Xia Wu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China
| | - Wen Kong
- Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China.
| | - Weijia Kong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China; Institute of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China.
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22
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Iizuka T, Kamiya K, Gotoh S, Sugitani Y, Suzuki M, Noda T, Minowa O, Ikeda K. Perinatal Gjb2 gene transfer rescues hearing in a mouse model of hereditary deafness. Hum Mol Genet 2015; 24:3651-61. [PMID: 25801282 DOI: 10.1093/hmg/ddv109] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 03/17/2015] [Indexed: 11/12/2022] Open
Abstract
Hearing loss is the most widespread sensory disorder, with an incidence of congenital genetic deafness of 1 in 1600 children. For many ethnic populations, the most prevalent form of genetic deafness is caused by recessive mutations in the gene gap junction protein, beta 2, 26 kDa (GJB2), which is also known as connexin 26 (Cx26). Despite this knowledge, existing treatment strategies do not completely recover speech perception. Here we used a gene delivery system to rescue hearing in a mouse model of Gjb2 deletion. Mice lacking Cx26 are characterized by profound deafness from birth and improper development of cochlear cells. Cochlear delivery of Gjb2 using an adeno-associated virus significantly improved the auditory responses and development of the cochlear structure. Using gene replacement to restore hearing in a new mouse model of Gjb2-related deafness may lead to the development of therapies for human hereditary deafness.
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Affiliation(s)
- Takashi Iizuka
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 113-8421, Japan
| | - Kazusaku Kamiya
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 113-8421, Japan
| | - Satoru Gotoh
- Department of Cell Biology, Japanese Foundation for Cancer Research, Cancer Institute, Tokyo 135-8550, Japan
| | - Yoshinobu Sugitani
- Department of Cell Biology, Japanese Foundation for Cancer Research, Cancer Institute, Tokyo 135-8550, Japan
| | - Masaaki Suzuki
- Department of Otolaryngology, Teikyo University Chiba Medical Center, Ichihara 299-0111, Japan and
| | - Tetsuo Noda
- Department of Cell Biology, Japanese Foundation for Cancer Research, Cancer Institute, Tokyo 135-8550, Japan, Team for Advanced Development and Evaluation of Human Disease Models, RIKEN BioResource Center, Tsukuba 305-0074, Japan
| | - Osamu Minowa
- Department of Cell Biology, Japanese Foundation for Cancer Research, Cancer Institute, Tokyo 135-8550, Japan, Team for Advanced Development and Evaluation of Human Disease Models, RIKEN BioResource Center, Tsukuba 305-0074, Japan
| | - Katsuhisa Ikeda
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo 113-8421, Japan,
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23
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Yu J, Wang Y, Liu P, Li Q, Sun Y, Kong W. Mitochondrial DNA common deletion increases susceptibility to noise-induced hearing loss in a mimetic aging rat model. Biochem Biophys Res Commun 2014; 453:515-20. [PMID: 25285633 DOI: 10.1016/j.bbrc.2014.09.118] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 09/26/2014] [Indexed: 12/20/2022]
Abstract
Noise-induced hearing loss (NIHL) is an important occupational health hazard. However, susceptibility to NIHL remains poorly understood. The present study was designed to investigate whether mitochondrial DNA common deletion (CD) increases the susceptibility of individuals to NIHL. A mimetic aging rat model harboring increased CD in the inner ear was established by chronic d-galactose administration, and the synergic effect of CD and noise on hearing sensitivity was assessed. We determined that although developed the same magnitude of temporary threshold shifts and hair cell loss, the d-galactose treated rats with increased CD in the inner ear exhibited a longer hearing recovery process and experienced higher permanent hearing threshold shifts at high frequencies than the saline-treated control rats. Greater supporting cell damage and stria vascularis ultrastructural changes were observed in d-galactose treated rats three weeks after recovery. The results suggested that the elevated CD in the inner ear could increase an individual's susceptibility to NIHL, which likely through a reduction in the self-repairing capability within the cochlea after acoustic injury.
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Affiliation(s)
- Jintao Yu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; Department of Otolaryngology-Head and Neck Surgery, Xiangya Hospital, Central South University, Changsha 410008, China
| | - Yanjun Wang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Peng Liu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Qingyu Li
- 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.
| | - Weijia Kong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
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24
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Wu X, Wang Y, Sun Y, Chen S, Zhang S, Shen L, Huang X, Lin X, Kong W. Reduced expression of Connexin26 and its DNA promoter hypermethylation in the inner ear of mimetic aging rats induced by d-galactose. Biochem Biophys Res Commun 2014; 452:340-6. [PMID: 25159847 DOI: 10.1016/j.bbrc.2014.08.063] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 08/12/2014] [Indexed: 01/21/2023]
Abstract
Connexin26 (Cx26), one of the major protein subunits forming gap junctions (GJs), is important in maintaining homeostasis in the inner ear and normal hearing. Cx26 mutation is one of the most common causes for inherited nonsyndromic deafness, but the relationship between Cx26 and presbycusis is unknown. Our study aimed at exploring the expression and the aberrant methylation of the promoter region of Cx26 gene in the cochlea of inner ear mimetic aging rats. We applied a mimetic aging of inner ear rat model with mtDNA common deletion by d-gal injection for 8weeks. Real-time RT-PCR and Western blot of rat inner ear tissue indicated that the Cx26 expression decreased in the d-gal group. Further bisulfite sequencing analysis revealed that the methylation status of the promoter region of Cx26 gene in the d-gal group was higher than that in control group. These results indicated that the decrease of Cx26 expression might contribute to the development of presbycusis and the hypermethylation of promoter region of GJB2 might be associated with the Cx26 downregulation.
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Affiliation(s)
- Xia Wu
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China
| | - Yanjun Wang
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China
| | - Yu Sun
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China.
| | - Sen Chen
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China
| | - Shuai Zhang
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China
| | - Ling Shen
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China
| | - Xiang Huang
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China
| | - Xi Lin
- Department of Otolaryngology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322-3030, USA
| | - Weijia Kong
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China; Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, PR China.
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25
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Chen J, Chen J, Zhu Y, Liang C, Zhao HB. Deafness induced by Connexin 26 (GJB2) deficiency is not determined by endocochlear potential (EP) reduction but is associated with cochlear developmental disorders. Biochem Biophys Res Commun 2014; 448:28-32. [PMID: 24732355 DOI: 10.1016/j.bbrc.2014.04.016] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 04/06/2014] [Indexed: 10/25/2022]
Abstract
Connexin 26 (Cx26, GJB2) mutations are the major cause of hereditary deafness and are responsible for >50% of nonsyndromic hearing loss. Mouse models show that Cx26 deficiency can cause congenital deafness with cochlear developmental disorders, hair cell degeneration, and the reduction of endocochlear potential (EP) and active cochlear amplification. However, the underlying deafness mechanism still remains undetermined. Our previous studies revealed that hair cell degeneration is not a primary cause of hearing loss. In this study we investigated the role of EP reduction in Cx26 deficiency-induced deafness. We found that the EP reduction is not associated with congenital deafness in Cx26 knockout (KO) mice. The threshold of auditory brainstem response (ABR) in Cx26 KO mice was even greater than 110 dB SPL, demonstrating complete hearing loss. However, the EP in Cx26 KO mice varied and not completely abolished. In some cases, the EP could still remain at higher levels (>70 mV). We further found that the deafness in Cx26 KO mice is associated with cochlear developmental disorders. Deletion of Cx26 in the cochlea before postnatal day 5 (P5) could cause congenital deafness. The cochlea had developmental disorders and the cochlear tunnel was not open. However, no congenital deafness was found when Cx26 was deleted after P5. The cochlea also displayed normal development and the cochlear tunnel was open normally. These data suggest that congenital deafness induced by Cx26 deficiency is not determined by EP reduction and may result from cochlear developmental disorders.
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Affiliation(s)
- Jin Chen
- Dept. of Otolaryngology, University of Kentucky Medical School, Lexington, KY 40536, USA.; Department of Otolaryngology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
| | - Jing Chen
- Dept. of Otolaryngology, University of Kentucky Medical School, Lexington, KY 40536, USA
| | - Yan Zhu
- Dept. of Otolaryngology, University of Kentucky Medical School, Lexington, KY 40536, USA
| | - Chun Liang
- Dept. of Otolaryngology, University of Kentucky Medical School, Lexington, KY 40536, USA
| | - Hong-Bo Zhao
- Dept. of Otolaryngology, University of Kentucky Medical School, Lexington, KY 40536, USA..
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