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Cepeda AP, Ninov M, Neef J, Parfentev I, Kusch K, Reisinger E, Jahn R, Moser T, Urlaub H. Proteomic Analysis Reveals the Composition of Glutamatergic Organelles of Auditory Inner Hair Cells. Mol Cell Proteomics 2024; 23:100704. [PMID: 38128648 PMCID: PMC10832297 DOI: 10.1016/j.mcpro.2023.100704] [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: 05/31/2023] [Revised: 11/08/2023] [Accepted: 12/18/2023] [Indexed: 12/23/2023] Open
Abstract
In the ear, inner hair cells (IHCs) employ sophisticated glutamatergic ribbon synapses with afferent neurons to transmit auditory information to the brain. The presynaptic machinery responsible for neurotransmitter release in IHC synapses includes proteins such as the multi-C2-domain protein otoferlin and the vesicular glutamate transporter 3 (VGluT3). Yet, much of this likely unique molecular machinery remains to be deciphered. The scarcity of material has so far hampered biochemical studies which require large amounts of purified samples. We developed a subcellular fractionation workflow combined with immunoisolation of VGluT3-containing membrane vesicles, allowing for the enrichment of glutamatergic organelles that are likely dominated by synaptic vesicles (SVs) of IHCs. We have characterized their protein composition in mice before and after hearing onset using mass spectrometry and confocal imaging and provide a fully annotated proteome with hitherto unidentified proteins. Despite the prevalence of IHC marker proteins across IHC maturation, the profiles of trafficking proteins differed markedly before and after hearing onset. Among the proteins enriched after hearing onset were VAMP-7, syntaxin-7, syntaxin-8, syntaxin-12/13, SCAMP1, V-ATPase, SV2, and PKCα. Our study provides an inventory of the machinery associated with synaptic vesicle-mediated trafficking and presynaptic activity at IHC ribbon synapses and serves as a foundation for future functional studies.
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Affiliation(s)
- Andreia P Cepeda
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Momchil Ninov
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Department of Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Jakob Neef
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany; Auditory Neuroscience & Synaptic Nanophysiology Group Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Iwan Parfentev
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Kathrin Kusch
- Functional Auditory Genomics Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Ellen Reisinger
- Gene Therapy for Hearing Impairment and Deafness, Department for Otolaryngology, Head & Neck Surgery, University Hospital Tübingen, Tübingen, Germany
| | - Reinhard Jahn
- Laboratory of Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany.
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany; Auditory Neuroscience & Synaptic Nanophysiology Group Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany.
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Department of Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany.
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2
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Li G, Gao Y, Wu H, Zhao T. Gentamicin administration leads to synaptic dysfunction in inner hair cells. Toxicol Lett 2024; 391:86-99. [PMID: 38101494 DOI: 10.1016/j.toxlet.2023.12.007] [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: 08/18/2023] [Revised: 11/17/2023] [Accepted: 12/11/2023] [Indexed: 12/17/2023]
Abstract
Ototoxicity is a major side effect of aminoglycosides, which can cause irreversible hearing loss. Previous studies on aminoglycoside-induced ototoxicity have primarily focused on the loss of sensory hair cells. Recent investigations have revealed that aminoglycosides can also lead to the loss of ribbon synapses in inner hair cells (IHCs). However, the functional implications of ribbon synapse loss and the underlying mechanisms remain unclear. In this study, we intraperitoneally injected C57BL/6 J mice with 300 mg/kg gentamicin once daily for 3, 10, and 20 days. Then, we performed immunofluorescence staining, patch-clamp recording, proteomics analysis and western blotting to characterize the changes in ribbon synapses in IHCs and the associated mechanisms. After gentamicin treatment, the auditory brainstem response (ABR) threshold was elevated, and the ABR wave I amplitude was decreased. We also observed loss of ribbon synapses in IHCs. Interestingly, ribbon synapse loss occurred on both the modiolar and pillar sides of IHCs. Whole-cell patch-clamp recordings in IHCs revealed a reduction in the calcium current amplitude, along with a shifted half-activation voltage and altered calcium voltage dependency. Moreover, exocytosis of IHCs was reduced, consistent with the reduction in the ABR wave I amplitude. Through proteomic analysis, western blotting, and immunofluorescence staining, we found that gentamicin treatment resulted in downregulation of myosin VI, a protein crucial for synaptic vesicle recycling and replenishment in IHCs. Furthermore, we evaluated the kinetics of endocytosis and found a significant reduction in IHC exocytosis, possibly reflecting the impact of myosin VI downregulation on synaptic vesicle recycling. In summary, our findings demonstrate that gentamicin treatment leads to synaptic dysfunction in IHCs, highlighting the important role of myosin VI downregulation in gentamicin-induced synaptic damage.
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Affiliation(s)
- Gen Li
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Yunge Gao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Hao Wu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
| | - Ting Zhao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
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3
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Yin N, Zhao J, Zhang P, Yu B, Chai R, Li GL. Functional and developmental changes in the inner hair cell ribbon synapses caused by Myosin VI knockout and deafness-inducing point mutation. Cell Death Discov 2023; 9:177. [PMID: 37258513 DOI: 10.1038/s41420-023-01473-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 04/27/2023] [Accepted: 05/16/2023] [Indexed: 06/02/2023] Open
Abstract
Hearing loss is one of the most common neurosensory disorders in humans, and above half of hearing loss is caused by gene mutations. Among more than 100 genes that cause non-syndromic hearing loss, myosin VI (MYO6) is typical in terms of the complexity of underlying mechanisms, which are not well understood. In this study, we used both knock-out (Myo6-/-) and point mutation (Myo6C442Y) mice as animal models, performed whole-cell patch-clamp recording and capacitance measurement in the inner hair cells (IHCs) in the cochlea, and sought to reveal potential functional and developmental changes in their ribbon synapses. In Myo6-/- cochleae of both before (P8-10) and after hearing onset (P18-20), exocytosis from IHCs, measured in whole-cell capacitance change (ΔCm), was significantly reduced, Ca2+ current amplitude (ICa) was unchanged, but Ca2+ voltage dependency was differently altered, causing significant increase in Ca2+ influx in mature IHCs but not in immature IHCs. In immature IHCs of Myo6C442Y/C442Y cochleae, neither ΔCm nor ICa was altered, but both were reduced in mature IHCs of the same animal model. Furthermore, while the reduction of exocytosis was caused by a combination of the slower rate of depleting readily releasable (RRP) pool of synaptic vesicles and slower sustained release rate (SRR) in Myo6-/- immature IHCs, it was likely due to smaller RRP and slower SRR in mature IHCs of both animal models. These results expand our understanding of the mechanisms of deafness caused by MYO6 mutations, and provide a solid theoretical and scientific basis for the diagnosis and treatment of deafness.
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Affiliation(s)
- Ning Yin
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
| | - Jingjing Zhao
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China
| | - Panpan Zhang
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China
- Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
| | - Baofu Yu
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, 200011, China
| | - Renjie Chai
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China.
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China.
- Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China.
| | - Geng-Lin Li
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China.
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China.
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China.
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Li X, Shi L, Wang L. A review of the mechanisms underlying the role of the GIPC3 gene in hereditary deafness. Front Synaptic Neurosci 2023; 14:1101587. [PMID: 36704659 PMCID: PMC9872657 DOI: 10.3389/fnsyn.2022.1101587] [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: 11/18/2022] [Accepted: 12/16/2022] [Indexed: 01/09/2023] Open
Abstract
The GAIP interacting protein c terminus (GIPC) genes encode a small family of proteins characterized by centrally located PDZ domains. GIPC3 encodes a 312 amino acid protein. Variants of human GIPC3 are associated with non-syndromic hearing loss. GIPC3 is one of over a hundred different genes with variants causing human deafness. Screening for variants of GIPC3 is essential for early detection of hearing loss in children and eventually treatment of deafness. Accordingly, this paper assesses the status of research developments on the role of GIPC3 in hereditary deafness and the effects of pathogenic variants on the auditory system.
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Affiliation(s)
- Xinxin Li
- Department of Otolaryngology, First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Lin Shi
- Department of Otolaryngology, First Affiliated Hospital of Dalian Medical University, Dalian, China,*Correspondence: Lin Shi,
| | - Liang Wang
- National Joint Engineering Laboratory, Stem Cell Clinical Research Center, Regenerative Medicine Center, First Affiliated Hospital of Dalian Medical University, Dalian, China,Liang Wang,
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Xu Z, Tu S, Pass C, Zhang Y, Liu H, Diers J, Fu Y, He DZZ, Zuo J. Profiling mouse cochlear cell maturation using 10× Genomics single-cell transcriptomics. Front Cell Neurosci 2022; 16:962106. [PMID: 36060279 PMCID: PMC9434313 DOI: 10.3389/fncel.2022.962106] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Accepted: 07/26/2022] [Indexed: 11/13/2022] Open
Abstract
Juvenile and mature mouse cochleae contain various low-abundant, vulnerable sensory epithelial cells embedded in the calcified temporal bone, making it challenging to profile the dynamic transcriptome changes of these cells during maturation at the single-cell level. Here we performed the 10x Genomics single-cell RNA sequencing (scRNA-seq) of mouse cochleae at postnatal days 14 (P14) and 28. We attained the transcriptomes of multiple cell types, including hair cells, supporting cells, spiral ganglia, stria fibrocytes, and immune cells. Our hair cell scRNA-seq datasets are consistent with published transcripts from bulk RNA-seq. We also mapped known deafness genes to corresponding cochlear cell types. Importantly, pseudotime trajectory analysis revealed that inner hair cell maturation peaks at P14 while outer hair cells continue development until P28. We further identified and confirmed a long non-coding RNA gene Miat to be expressed during maturation in cochlear hair cells and spiral ganglia neurons, and Pcp4 to be expressed during maturation in cochlear hair cells. Our transcriptomes of juvenile and mature mouse cochlear cells provide the sequel to those previously published at late embryonic and early postnatal ages and will be valuable resources to investigate cochlear maturation at the single-cell resolution.
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Affiliation(s)
- Zhenhang Xu
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States
| | - Shu Tu
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States
| | - Caroline Pass
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States
| | - Yan Zhang
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States
| | - Huizhan Liu
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States
| | - Jack Diers
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States
| | - Yusi Fu
- Lynch Comprehensive Cancer Research Center, Creighton University School of Medicine, Omaha, NE, United States
| | - David Z. Z. He
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States
| | - Jian Zuo
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States
- *Correspondence: Jian Zuo,
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6
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Guo R, Xu Y, Xiong W, Wei W, Qi Y, Du Z, Gong S, Tao Z, Liu K. Autophagy-Mediated Synaptic Refinement and Auditory Neural Pruning Contribute to Ribbon Synaptic Maturity in the Developing Cochlea. Front Mol Neurosci 2022; 15:850035. [PMID: 35310883 PMCID: PMC8931412 DOI: 10.3389/fnmol.2022.850035] [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: 01/07/2022] [Accepted: 01/28/2022] [Indexed: 11/13/2022] Open
Abstract
In rodents, massive initial synapses are formed in the auditory peripheral nervous system at the early postnatal stage, and one of the major phenomena is that the number of afferent synapses in the cochlea is significantly reduced in the duration of development. This raises the hypothesis that the number of cochlear ribbon synapses are dramatically changed with hearing development and maturation. In this study, several tracers identifying activities of autophagy were applied to estimate the level of autophagy activity in the process of ribbon synapse development in mice; further, changes in the synaptic number and spiral ganglion nerve (SGN) fibers were quantitatively measured. We found robust expression of LC3B and lysosomal-associated membrane protein 1 as well as LysoTracker in or near inner hair cells and cochlear ribbon synapses in the early stage of postnatal development. Moreover, we found a significant loss in the intensity of SGN fibers at ribbon synaptic development and hearing onset. Thus, this study demonstrates that ribbon synaptic refinement and SGN fibers pruning are closely associated with the morphological and functional maturation of ribbon synapses and that synaptic refinement and SGN fiber pruning are regulated by the robust activities of autophagy in the earlier stages of auditory development.
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Affiliation(s)
- Rui Guo
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Yice Xu
- Department of Otolaryngology Head and Neck Surgery, Xiaogan Central Hospital, Wuhan University of Science and Technology, Xiaogan, China
| | - Wei Xiong
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Wei Wei
- Department of Otology, Shengjing Hospital, China Medical University, Shenyang, China
| | - Yue Qi
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Zhengde Du
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Shusheng Gong
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- *Correspondence: Shusheng Gong,
| | - Zezhang Tao
- Department of Otolaryngology Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan, China
| | - Ke Liu
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- Ke Liu,
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7
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Vogl C, Neef J, Wichmann C. Methods for multiscale structural and functional analysis of the mammalian cochlea. Mol Cell Neurosci 2022; 120:103720. [DOI: 10.1016/j.mcn.2022.103720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 02/13/2022] [Accepted: 03/08/2022] [Indexed: 01/11/2023] Open
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Xue Y, Hu X, Wang D, Li D, Li Y, Wang F, Huang M, Gu X, Xu Z, Zhou J, Wang J, Chai R, Shen J, Chen ZY, Li GL, Yang H, Li H, Zuo E, Shu Y. Gene editing in a Myo6 semi-dominant mouse model rescues auditory function. Mol Ther 2022; 30:105-118. [PMID: 34174443 PMCID: PMC8753286 DOI: 10.1016/j.ymthe.2021.06.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 04/29/2021] [Accepted: 06/21/2021] [Indexed: 01/07/2023] Open
Abstract
Myosin VI(MYO6) is an unconventional myosin that is vital for auditory and vestibular function. Pathogenic variants in the human MYO6 gene cause autosomal-dominant or -recessive forms of hearing loss. Effective treatments for Myo6 mutation causing hearing loss are limited. We studied whether adeno-associated virus (AAV)-PHP.eB vector-mediated in vivo delivery of Staphylococcus aureus Cas9 (SaCas9-KKH)-single-guide RNA (sgRNA) complexes could ameliorate hearing loss in a Myo6WT/C442Y mouse model that recapitulated the phenotypes of human patients. The in vivo editing efficiency of the AAV-SaCas9-KKH-Myo6-g2 system on Myo6C442Y is 4.05% on average in Myo6WT/C442Y mice, which was ∼17-fold greater than editing efficiency of Myo6WT alleles. Rescue of auditory function was observed up to 5 months post AAV-SaCas9-KKH-Myo6-g2 injection in Myo6WT/C442Y mice. Meanwhile, shorter latencies of auditory brainstem response (ABR) wave I, lower distortion product otoacoustic emission (DPOAE) thresholds, increased cell survival rates, more regular hair bundle morphology, and recovery of inward calcium levels were also observed in the AAV-SaCas9-KKH-Myo6-g2-treated ears compared to untreated ears. These findings provide further reference for in vivo genome editing as a therapeutic treatment for various semi-dominant forms of hearing loss and other semi-dominant diseases.
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Affiliation(s)
- Yuanyuan Xue
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200031, China
| | - Xinde Hu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Key Laboratory of Primate Neurobiology, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Daqi Wang
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200031, China
| | - Di Li
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518124, China; State Key Lab for Conservation and Utilization of Subtropical Agric-Biological Resources, Guangxi University, Nanning 530005, China
| | - Yige Li
- MOE Key Laboratory for Developmental Genes and Human Disease, School of Life Sciences and Technology, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China
| | - Fang Wang
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200031, China
| | - Mingqian Huang
- Department of Otolaryngology-Head and Neck Surgery, Graduate Program in Speech and Hearing Bioscience and Technology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA; Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA
| | - Xi Gu
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200031, China
| | - Zhijiao Xu
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200031, China
| | - Jinan Zhou
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200031, China
| | - Jinghan Wang
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200031, China
| | - Renjie Chai
- MOE Key Laboratory for Developmental Genes and Human Disease, School of Life Sciences and Technology, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China; Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226001, China; Institute for Stem Cell and Regeneration, Chinese Academy of Science, Beijing, Shanghai 200032, China
| | - Jun Shen
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA; Harvard Medical School Center for Hereditary Deafness, Boston, MA 02115, USA
| | - Zheng-Yi Chen
- Department of Otolaryngology-Head and Neck Surgery, Graduate Program in Speech and Hearing Bioscience and Technology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA; Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA
| | - Geng-Lin Li
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200031, China
| | - Hui Yang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Huawei Li
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200031, China; The Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China.
| | - Erwei Zuo
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518124, China.
| | - Yilai Shu
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai 200031, China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China; NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai 200031, China.
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9
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Myosin VI Haploinsufficiency Reduced Hearing Ability in Mice. Neuroscience 2021; 478:100-111. [PMID: 34619316 DOI: 10.1016/j.neuroscience.2021.09.023] [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: 05/27/2021] [Revised: 09/10/2021] [Accepted: 09/27/2021] [Indexed: 11/22/2022]
Abstract
In human, myosin VI (MYO6) haploinsufficiency causes postlingual progressive hearing loss. Because the usefulness of mouse models remains unclear, we produced novel Myo6 null (-/-) mutant mice and analyzed the hearing phenotypes of Myo6+/- (+/-) heterozygous mutants. We first recorded and compared the auditory brainstem responses and distortion product otoacoustic emissions in control Myo6+/+ (+/+) wild-type and +/- mice. These hearing phenotypes of +/- mice were mild; however, we confirmed that +/- mice developed progressive hearing loss. In particular, the hearing loss of female +/- mice progressed faster than that of male +/- mice. The stereocilia bundles of +/- mice exhibited progressive taper loss in cochlear inner hair cells (IHCs) and outer hair cells (OHCs). The loss of OHCs in +/- heterozygotes occurred at an earlier age than in +/+ mice. In particular, the OHCs at the basal area of the cochlea were decreased in +/- mice. IHC ribbon synapses from the area at the base of the cochlea were significantly reduced in +/- mice. Thus, our study indicated that MYO6 haploinsufficiency affected the detection of sounds in mice, and we suggest that +/- mice with Myo6 null alleles are useful animal models for gene therapy and drug treatment in patients with progressive hearing loss due to MYO6 haploinsufficiency.
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10
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Trigila AP, Pisciottano F, Franchini LF. Hearing loss genes reveal patterns of adaptive evolution at the coding and non-coding levels in mammals. BMC Biol 2021; 19:244. [PMID: 34784928 PMCID: PMC8594068 DOI: 10.1186/s12915-021-01170-6] [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: 11/20/2020] [Accepted: 10/21/2021] [Indexed: 11/26/2022] Open
Abstract
Background Mammals possess unique hearing capacities that differ significantly from those of the rest of the amniotes. In order to gain insights into the evolution of the mammalian inner ear, we aim to identify the set of genetic changes and the evolutionary forces that underlie this process. We hypothesize that genes that impair hearing when mutated in humans or in mice (hearing loss (HL) genes) must play important roles in the development and physiology of the inner ear and may have been targets of selective forces across the evolution of mammals. Additionally, we investigated if these HL genes underwent a human-specific evolutionary process that could underlie the evolution of phenotypic traits that characterize human hearing. Results We compiled a dataset of HL genes including non-syndromic deafness genes identified by genetic screenings in humans and mice. We found that many genes including those required for the normal function of the inner ear such as LOXHD1, TMC1, OTOF, CDH23, and PCDH15 show strong signatures of positive selection. We also found numerous noncoding accelerated regions in HL genes, and among them, we identified active transcriptional enhancers through functional enhancer assays in transgenic zebrafish. Conclusions Our results indicate that the key inner ear genes and regulatory regions underwent adaptive evolution in the basal branch of mammals and along the human-specific branch, suggesting that they could have played an important role in the functional remodeling of the cochlea. Altogether, our data suggest that morphological and functional evolution could be attained through molecular changes affecting both coding and noncoding regulatory regions. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01170-6.
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Affiliation(s)
- Anabella P Trigila
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1428, Buenos Aires, Argentina
| | - Francisco Pisciottano
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1428, Buenos Aires, Argentina.,Current address: Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1428, Buenos Aires, Argentina
| | - Lucía F Franchini
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1428, Buenos Aires, Argentina.
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11
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Frohne A, Koenighofer M, Liu DT, Laccone F, Neesen J, Gstoettner W, Schoefer C, Lucas T, Frei K, Parzefall T. High Prevalence of MYO6 Variants in an Austrian Patient Cohort With Autosomal Dominant Hereditary Hearing Loss. Otol Neurotol 2021; 42:e648-e657. [PMID: 33710140 DOI: 10.1097/mao.0000000000003076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
INTRODUCTION Genetic hearing loss (HL) is often monogenic. Whereas more than half of autosomal recessive (AR) cases in Austria are caused by mutations in a single gene, no disproportionately frequent contributing genetic factor has been identified in cases of autosomal dominant (AD) HL. The genetic characterization of HL continues to improve diagnosis, genetic counseling, and lays a foundation for the development of personalized medicine approaches. METHODS Diagnostic HL panel screening was performed in an Austrian multiplex family with AD HL, and segregation was tested with polymerase chain reaction and Sanger sequencing. In an independent approach, 18 unrelated patients with AD HL were screened for causative variants in all known HL genes to date and segregation was tested if additional family members were available. The pathogenicity of novel variants was assessed based on previous literature and bioinformatic tools such as prediction software and protein modeling. RESULTS In six of the 19 families under study, candidate pathogenic variants were identified in MYO6, including three novel variants (p.Gln441Pro, p.Ser612Tyr, and p.Gln650ValfsTer7). Some patients carried more than one likely pathogenic variant in known deafness genes. CONCLUSION These results suggest a potential high prevalence of MYO6 variants in Austrian cases of AD HL. The presence of multiple rare HL variants in some patients highlights the relevance of considering multiple-hit diagnoses for genetic counseling and targeted therapy design.
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Affiliation(s)
- Alexandra Frohne
- Department of Otorhinolaryngology, Head and Neck Surgery
- Department for Cell and Developmental Biology, Center for Anatomy and Cell Biology
| | | | | | - Franco Laccone
- Institute of Medical Genetics, Center for Pathobiochemistry and Genetics, Medical University of Vienna, Vienna, Austria
| | - Juergen Neesen
- Institute of Medical Genetics, Center for Pathobiochemistry and Genetics, Medical University of Vienna, Vienna, Austria
| | | | - Christian Schoefer
- Department for Cell and Developmental Biology, Center for Anatomy and Cell Biology
| | - Trevor Lucas
- Department for Cell and Developmental Biology, Center for Anatomy and Cell Biology
| | - Klemens Frei
- Department of Otorhinolaryngology, Head and Neck Surgery
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12
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Zakrzewski P, Lenartowska M, Buss F. Diverse functions of myosin VI in spermiogenesis. Histochem Cell Biol 2021; 155:323-340. [PMID: 33386429 PMCID: PMC8021524 DOI: 10.1007/s00418-020-01954-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2020] [Indexed: 02/07/2023]
Abstract
Spermiogenesis is the final stage of spermatogenesis, a differentiation process during which unpolarized spermatids undergo excessive remodeling that results in the formation of sperm. The actin cytoskeleton and associated actin-binding proteins play crucial roles during this process regulating organelle or vesicle delivery/segregation and forming unique testicular structures involved in spermatid remodeling. In addition, several myosin motor proteins including MYO6 generate force and movement during sperm differentiation. MYO6 is highly unusual as it moves towards the minus end of actin filaments in the opposite direction to other myosin motors. This specialized feature of MYO6 may explain the many proposed functions of this myosin in a wide array of cellular processes in animal cells, including endocytosis, secretion, stabilization of the Golgi complex, and regulation of actin dynamics. These diverse roles of MYO6 are mediated by a range of specialized cargo-adaptor proteins that link this myosin to distinct cellular compartments and processes. During sperm development in a number of different organisms, MYO6 carries out pivotal functions. In Drosophila, the MYO6 ortholog regulates actin reorganization during spermatid individualization and male KO flies are sterile. In C. elegans, the MYO6 ortholog mediates asymmetric segregation of cytosolic material and spermatid budding through cytokinesis, whereas in mice, this myosin regulates assembly of highly specialized actin-rich structures and formation of membrane compartments to allow the formation of fully differentiated sperm. In this review, we will present an overview and compare the diverse function of MYO6 in the specialized adaptations of spermiogenesis in flies, worms, and mammals.
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Affiliation(s)
- Przemysław Zakrzewski
- Department of Cellular and Molecular Biology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, Torun, Poland.,Cambridge Institute for Medical Research, The Keith Peters Building, University of Cambridge, Hills Road, Cambridge, CB2 0XY, UK
| | - Marta Lenartowska
- Department of Cellular and Molecular Biology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, Torun, Poland.,Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Toruń, Torun, Poland
| | - Folma Buss
- Cambridge Institute for Medical Research, The Keith Peters Building, University of Cambridge, Hills Road, Cambridge, CB2 0XY, UK.
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13
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Voorn RA, Vogl C. Molecular Assembly and Structural Plasticity of Sensory Ribbon Synapses-A Presynaptic Perspective. Int J Mol Sci 2020; 21:E8758. [PMID: 33228215 PMCID: PMC7699581 DOI: 10.3390/ijms21228758] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 11/16/2020] [Accepted: 11/17/2020] [Indexed: 12/13/2022] Open
Abstract
In the mammalian cochlea, specialized ribbon-type synapses between sensory inner hair cells (IHCs) and postsynaptic spiral ganglion neurons ensure the temporal precision and indefatigability of synaptic sound encoding. These high-through-put synapses are presynaptically characterized by an electron-dense projection-the synaptic ribbon-which provides structural scaffolding and tethers a large pool of synaptic vesicles. While advances have been made in recent years in deciphering the molecular anatomy and function of these specialized active zones, the developmental assembly of this presynaptic interaction hub remains largely elusive. In this review, we discuss the dynamic nature of IHC (pre-) synaptogenesis and highlight molecular key players as well as the transport pathways underlying this process. Since developmental assembly appears to be a highly dynamic process, we further ask if this structural plasticity might be maintained into adulthood, how this may influence the functional properties of a given IHC synapse and how such plasticity could be regulated on the molecular level. To do so, we take a closer look at other ribbon-bearing systems, such as retinal photoreceptors and pinealocytes and aim to infer conserved mechanisms that may mediate these phenomena.
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MESH Headings
- Alcohol Oxidoreductases/genetics
- Alcohol Oxidoreductases/metabolism
- Animals
- Co-Repressor Proteins/genetics
- Co-Repressor Proteins/metabolism
- Cytoskeletal Proteins/genetics
- Cytoskeletal Proteins/metabolism
- Cytoskeleton/metabolism
- Cytoskeleton/ultrastructure
- Gene Expression Regulation, Developmental
- Hair Cells, Auditory, Inner/metabolism
- Hair Cells, Auditory, Inner/ultrastructure
- Hair Cells, Auditory, Outer/metabolism
- Hair Cells, Auditory, Outer/ultrastructure
- Hair Cells, Vestibular/metabolism
- Hair Cells, Vestibular/ultrastructure
- Mechanotransduction, Cellular
- Mice
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neuronal Plasticity/genetics
- Neuropeptides/genetics
- Neuropeptides/metabolism
- Rats
- Synapses/metabolism
- Synapses/ultrastructure
- Synaptic Transmission/genetics
- Synaptic Vesicles/metabolism
- Synaptic Vesicles/ultrastructure
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Affiliation(s)
- Roos Anouk Voorn
- Presynaptogenesis and Intracellular Transport in Hair Cells Junior Research Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Goettingen, 37075 Goettingen, Germany;
- Göttingen Graduate Center for Neurosciences, Biophysics and Molecular Biosciences, 37075 Goettingen, Germany
- Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing”, 37075 Goettingen, Germany
| | - Christian Vogl
- Presynaptogenesis and Intracellular Transport in Hair Cells Junior Research Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Goettingen, 37075 Goettingen, Germany;
- Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing”, 37075 Goettingen, Germany
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14
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Lan Y, Tao Y, Wang Y, Ke J, Yang Q, Liu X, Su B, Wu Y, Lin CP, Zhong G. Recent development of AAV-based gene therapies for inner ear disorders. Gene Ther 2020; 27:329-337. [PMID: 32424232 PMCID: PMC7445886 DOI: 10.1038/s41434-020-0155-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/12/2020] [Accepted: 04/27/2020] [Indexed: 01/07/2023]
Abstract
Gene therapy for auditory diseases is gradually maturing. Recent progress in gene therapy treatments for genetic and acquired hearing loss has demonstrated the feasibility in animal models. However, a number of hurdles, such as lack of safe viral vector with high efficiency and specificity, robust deafness large animal models, translating animal studies to clinic etc., still remain to be solved. It is necessary to overcome these challenges in order to effectively recover auditory function in human patients. Here, we review the progress made in our group, especially our efforts to make more effective and cell type-specific viral vectors for targeting cochlea cells.
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Affiliation(s)
- Yiyang Lan
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yong Tao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200011, China
| | - Yunfeng Wang
- ENT institute and Otorhinolaryngology Department of Eye & ENT Hospital, NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, China
| | - Junzi Ke
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Qiuxiang Yang
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Xiaoyi Liu
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Bing Su
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yiling Wu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Chao-Po Lin
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Guisheng Zhong
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China. .,School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
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15
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Hosoya M, Fujioka M, Murayama AY, Okano H, Ogawa K. The common marmoset as suitable nonhuman alternative for the analysis of primate cochlear development. FEBS J 2020; 288:325-353. [PMID: 32323465 PMCID: PMC7818239 DOI: 10.1111/febs.15341] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 01/30/2020] [Accepted: 04/20/2020] [Indexed: 12/13/2022]
Abstract
Cochlear development is a complex process with precise spatiotemporal patterns. A detailed understanding of this process is important for studies of congenital hearing loss and regenerative medicine. However, much of our understanding of cochlear development is based on rodent models. Animal models that bridge the gap between humans and rodents are needed. In this study, we investigated the development of hearing organs in a small New World monkey species, the common marmoset (Callithrix jacchus). We describe the general stages of cochlear development in comparison with those of humans and mice. Moreover, we examined more than 25 proteins involved in cochlear development and found that expression patterns were generally conserved between rodents and primates. However, several proteins involved in supporting cell processes and neuronal development exhibited interspecific expression differences. Human fetal samples for studies of primate‐specific cochlear development are extremely rare, especially for late developmental stages. Our results support the use of the common marmoset as an effective alternative for analyses of primate cochlear development.
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Affiliation(s)
- Makoto Hosoya
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Masato Fujioka
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Ayako Y Murayama
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan.,Laboratory for Marmoset Neural Architecture, Center for Brain Science, RIKEN, Wako, Japan
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan.,Laboratory for Marmoset Neural Architecture, Center for Brain Science, RIKEN, Wako, Japan
| | - Kaoru Ogawa
- Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo, Japan
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16
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Venugopal P, Gagliardi L, Forsyth C, Feng J, Phillips K, Babic M, Poplawski NK, Rienhoff HY, Schreiber AW, Hahn CN, Brown AL, Scott HS. Two monogenic disorders masquerading as one: severe congenital neutropenia with monocytosis and non-syndromic sensorineural hearing loss. BMC MEDICAL GENETICS 2020; 21:35. [PMID: 32066420 PMCID: PMC7026993 DOI: 10.1186/s12881-020-0971-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 02/11/2020] [Indexed: 11/10/2022]
Abstract
BACKGROUND We report a large family with four successive generations, presenting with a complex phenotype of severe congenital neutropenia (SCN), partially penetrant monocytosis, and hearing loss of varying severity. METHODS We performed whole exome sequencing to identify the causative variants. Sanger sequencing was used to perform segregation analyses on remaining family members. RESULTS We identified and classified a pathogenic GFI1 variant and a likely pathogenic variant in MYO6 which together explain the complex phenotypes seen in this family. CONCLUSIONS We present a case illustrating the benefits of a broad screening approach that allows identification of oligogenic determinants of complex human phenotypes which may have been missed if the screening was limited to a targeted gene panel with the assumption of a syndromic disorder. This is important for correct genetic diagnosis of families and disentangling the range and severity of phenotypes associated with high impact variants.
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Affiliation(s)
- Parvathy Venugopal
- Genetics and Molecular Pathology, SA Pathology, Adelaide, Australia.,Centre for Cancer Biology, an alliance between SA Pathology and the University of South Australia, Adelaide, Australia
| | - Lucia Gagliardi
- Genetics and Molecular Pathology, SA Pathology, Adelaide, Australia.,Centre for Cancer Biology, an alliance between SA Pathology and the University of South Australia, Adelaide, Australia.,School of Medicine, University of Adelaide, Adelaide, Australia.,Endocrine and Diabetes Unit, The Queen Elizabeth Hospital, Woodville South, Australia.,Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, Australia
| | | | - Jinghua Feng
- Australian Cancer Research Foundation Cancer Genomics Facility, Centre for Cancer Biology, SA Pathology, PO Box 14, Rundle Mall, Adelaide, South Australia, 5000, Australia.,School of Pharmacy and Medical Sciences, Division of Health Sciences, University of South Australia, Adelaide, Australia
| | - Kerry Phillips
- Adult Genetics Unit, Royal Adelaide Hospital, Adelaide, Australia
| | - Milena Babic
- Genetics and Molecular Pathology, SA Pathology, Adelaide, Australia.,Centre for Cancer Biology, an alliance between SA Pathology and the University of South Australia, Adelaide, Australia
| | | | | | - Andreas W Schreiber
- Centre for Cancer Biology, an alliance between SA Pathology and the University of South Australia, Adelaide, Australia.,Australian Cancer Research Foundation Cancer Genomics Facility, Centre for Cancer Biology, SA Pathology, PO Box 14, Rundle Mall, Adelaide, South Australia, 5000, Australia.,School of Pharmacy and Medical Sciences, Division of Health Sciences, University of South Australia, Adelaide, Australia.,School of Biological Sciences, University of Adelaide, Adelaide, Australia
| | - Christopher N Hahn
- Genetics and Molecular Pathology, SA Pathology, Adelaide, Australia.,Centre for Cancer Biology, an alliance between SA Pathology and the University of South Australia, Adelaide, Australia.,School of Medicine, University of Adelaide, Adelaide, Australia.,School of Pharmacy and Medical Sciences, Division of Health Sciences, University of South Australia, Adelaide, Australia
| | - Anna L Brown
- Genetics and Molecular Pathology, SA Pathology, Adelaide, Australia.,Centre for Cancer Biology, an alliance between SA Pathology and the University of South Australia, Adelaide, Australia.,School of Pharmacy and Medical Sciences, Division of Health Sciences, University of South Australia, Adelaide, Australia
| | - Hamish S Scott
- Genetics and Molecular Pathology, SA Pathology, Adelaide, Australia. .,Centre for Cancer Biology, an alliance between SA Pathology and the University of South Australia, Adelaide, Australia. .,School of Medicine, University of Adelaide, Adelaide, Australia. .,Australian Cancer Research Foundation Cancer Genomics Facility, Centre for Cancer Biology, SA Pathology, PO Box 14, Rundle Mall, Adelaide, South Australia, 5000, Australia. .,School of Pharmacy and Medical Sciences, Division of Health Sciences, University of South Australia, Adelaide, Australia.
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17
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Xiong W, Wei W, Qi Y, Du Z, Qu T, Liu K, Gong S. Autophagy is Required for Remodeling in Postnatal Developing Ribbon Synapses of Cochlear Inner Hair Cells. Neuroscience 2020; 431:1-16. [PMID: 32032574 DOI: 10.1016/j.neuroscience.2020.01.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 01/13/2020] [Accepted: 01/19/2020] [Indexed: 11/16/2022]
Abstract
Cochlear ribbon synapses formed between inner hair cells (IHCs) and spiral ganglion neurons (SGNs) are immature at birth and they require dramatic morphological and functional developments to achieve auditory maturation in postnatal mice. However, the mechanism underlying this remodeling process of cochlear ribbon synapse remains elusive. Here, we report that autophagy is necessary for the development and maturation of cochlear ribbon synapses in mice. In this study, significantly high levels of LC3B (a widespread marker of autophagy) were found in the cochlea from postnatal day 1 (P1) to P15, which then decreased at P28 to P30. Treatment of mice at P7 with rapamycin or 3-methyladenine (activator and inhibitor of autophagy, respectively) for 7 days led to the significant elevations of hearing threshold across frequencies from P15 to P30. Moreover, abnormal morphology of cochlear ribbon synapses and reduced IHC exocytosis function were detected from P15 to P30, which were likely associated to hearing impairment. Thus, our study demonstrated that autophagy was required for remodeling of cochlear ribbon synapses and provided a new insight into autophagy-related hearing disorder during auditory development. Furthermore, we implicated a novel therapeutic target for sensorineural hearing loss.
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Affiliation(s)
- Wei Xiong
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Wei Wei
- Department of Otolaryngology Head and Neck Surgery, Shengjing Hospital of China Medical University, Shenyang 110004, China
| | - Yue Qi
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Zhengde Du
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Tengfei Qu
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Ke Liu
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China.
| | - Shusheng Gong
- Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China.
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18
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O'Loughlin T, Kendrick-Jones J, Buss F. Approaches to Identify and Characterise MYO6-Cargo Interactions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1239:355-380. [PMID: 32451866 DOI: 10.1007/978-3-030-38062-5_15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Given the prevalence and importance of the actin cytoskeleton and the host of associated myosin motors, it comes as no surprise to find that they are linked to a plethora of cellular functions and pathologies. Although our understanding of the biophysical properties of myosin motors has been aided by the high levels of conservation in their motor domains and the extensive work on myosin in skeletal muscle contraction, our understanding of how the nonmuscle myosins participate in such a wide variety of cellular processes is less clear. It is now well established that the highly variable myosin tails are responsible for targeting these myosins to distinct cellular sites for specific functions, and although a number of adaptor proteins have been identified, our current understanding of the cellular processes involved is rather limited. Furthermore, as more adaptor proteins, cargoes and complexes are identified, the importance of elucidating the regulatory mechanisms involved is essential. Ca2+, and now phosphorylation and ubiquitination, are emerging as important regulators of cargo binding, and it is likely that other post-translational modifications are also involved. In the case of myosin VI (MYO6), a number of immediate binding partners have been identified using traditional approaches such as yeast two-hybrid screens and affinity-based pull-downs. However, these methods have only been successful in identifying the cargo adaptors, but not the cargoes themselves, which may often comprise multi-protein complexes. Furthermore, motor-adaptor-cargo interactions are dynamic by nature and often weak, transient and highly regulated and therefore difficult to capture using traditional affinity-based methods. In this chapter we will discuss the various approaches including functional proteomics that have been used to uncover and characterise novel MYO6-associated proteins and complexes and how this work contributes to a fuller understanding of the targeting and function(s) of this unique myosin motor.
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Affiliation(s)
- Thomas O'Loughlin
- Cambridge Institute for Medical Research, University of Cambridge, The Keith Peters Building, Cambridge, UK
| | | | - Folma Buss
- Cambridge Institute for Medical Research, University of Cambridge, The Keith Peters Building, Cambridge, UK.
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19
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de Jonge JJ, Batters C, O'Loughlin T, Arden SD, Buss F. The MYO6 interactome: selective motor-cargo complexes for diverse cellular processes. FEBS Lett 2019; 593:1494-1507. [PMID: 31206648 DOI: 10.1002/1873-3468.13486] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/07/2019] [Accepted: 06/10/2019] [Indexed: 12/16/2022]
Abstract
Myosins of class VI (MYO6) are unique actin-based motor proteins that move cargo towards the minus ends of actin filaments. As the sole myosin with this directionality, it is critically important in a number of biological processes. Indeed, loss or overexpression of MYO6 in humans is linked to a variety of pathologies including deafness, cardiomyopathy, neurodegenerative diseases as well as cancer. This myosin interacts with a wide variety of direct binding partners such as for example the selective autophagy receptors optineurin, TAX1BP1 and NDP52 and also Dab2, GIPC, TOM1 and LMTK2, which mediate distinct functions of different MYO6 isoforms along the endocytic pathway. Functional proteomics has recently been used to identify the wider MYO6 interactome including several large functionally distinct multi-protein complexes, which highlight the importance of this myosin in regulating the actin and septin cytoskeleton. Interestingly, adaptor-binding not only triggers cargo attachment, but also controls the inactive folded conformation and dimerisation of MYO6. Thus, the C-terminal tail domain mediates cargo recognition and binding, but is also crucial for modulating motor activity and regulating cytoskeletal track dynamics.
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Affiliation(s)
| | | | - Thomas O'Loughlin
- Cambridge Institute for Medical Research, University of Cambridge, UK
| | - Susan D Arden
- Cambridge Institute for Medical Research, University of Cambridge, UK
| | - Folma Buss
- Cambridge Institute for Medical Research, University of Cambridge, UK
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20
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Chakrabarti R, Wichmann C. Nanomachinery Organizing Release at Neuronal and Ribbon Synapses. Int J Mol Sci 2019; 20:E2147. [PMID: 31052288 PMCID: PMC6539712 DOI: 10.3390/ijms20092147] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 04/26/2019] [Accepted: 04/26/2019] [Indexed: 11/17/2022] Open
Abstract
A critical aim in neuroscience is to obtain a comprehensive view of how regulated neurotransmission is achieved. Our current understanding of synapses relies mainly on data from electrophysiological recordings, imaging, and molecular biology. Based on these methodologies, proteins involved in a synaptic vesicle (SV) formation, mobility, and fusion at the active zone (AZ) membrane have been identified. In the last decade, electron tomography (ET) combined with a rapid freezing immobilization of neuronal samples opened a window for understanding the structural machinery with the highest spatial resolution in situ. ET provides significant insights into the molecular architecture of the AZ and the organelles within the presynaptic nerve terminal. The specialized sensory ribbon synapses exhibit a distinct architecture from neuronal synapses due to the presence of the electron-dense synaptic ribbon. However, both synapse types share the filamentous structures, also commonly termed as tethers that are proposed to contribute to different steps of SV recruitment and exocytosis. In this review, we discuss the emerging views on the role of filamentous structures in SV exocytosis gained from ultrastructural studies of excitatory, mainly central neuronal compared to ribbon-type synapses with a focus on inner hair cell (IHC) ribbon synapses. Moreover, we will speculate on the molecular entities that may be involved in filament formation and hence play a crucial role in the SV cycle.
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Affiliation(s)
- Rituparna Chakrabarti
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, 37075 Göttingen, Germany.
- Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing", 37099 Göttingen, Germany.
| | - Carolin Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, 37075 Göttingen, Germany.
- Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing", 37099 Göttingen, Germany.
- Collaborative Research Center 1286 "Quantitative Synaptology", 37099 Göttingen, Germany.
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany.
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Wang J, Shen J, Guo L, Cheng C, Chai R, Shu Y, Li H. A humanized mouse model, demonstrating progressive hearing loss caused by MYO6 p.C442Y, is inherited in a semi-dominant pattern. Hear Res 2019; 379:79-88. [PMID: 31103816 DOI: 10.1016/j.heares.2019.04.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 04/22/2019] [Accepted: 04/24/2019] [Indexed: 11/28/2022]
Abstract
Myosin VI is an actin-associated molecular motor vital for auditory and vestibular function. It is encoded by MYO6 located on chromosome 6q13 in human. Pathogenic variants in MYO6 have been associated with both dominant and recessive forms of hearing loss. However, the molecular mechanisms remain unclear. We established a humanized knock-in mouse model, Myo6-C442Y, to mimic the p.C442Y missense variant identified in human patients with autosomal dominant nonsyndromic hearing loss designated as DFNA22. We characterized hearing and inner ear morphologies of Myo6-C442Y and wild-type control mice. We found that both homozygous and heterozygous Myo6-C442Y mice exhibited hearing loss from three weeks after birth that rapidly progressed to profound deafness by six to nine weeks of age. The hearing loss corresponded to the degeneration of hair cells in the organ of Corti. We also observed disorganized stereocilia with irregular morphological features by immunohistochemistry and scanning electron microscopy. Additionally, hearing loss and inner-ear morphological anomalies were more pronounced and deteriorated more drastically in homozygous than in heterozygous Myo6-C442Y mice, indicating a semi-dominant inheritance pattern. Heterozygous Myo6-C442Y mice recapitulated the progressive postlingual sensorineural deafness in human, thus providing a useful model for elucidating the role myosin VI plays in the mammalian auditory system. Furthermore, the late-onset hearing loss of this mouse model may provide a therapeutic window for the emerging gene therapy, a promising strategy to treat certain forms of genetic deafness.
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Affiliation(s)
- Jinghan Wang
- ENT Institute and Otorhinolaryngology Department, Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, 200031, China
| | - Jun Shen
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Luo Guo
- ENT Institute and Otorhinolaryngology Department, Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, 200031, China
| | - Cheng Cheng
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China; Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Renjie Chai
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China; Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China
| | - Yilai Shu
- ENT Institute and Otorhinolaryngology Department, Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, 200031, China.
| | - Huawei Li
- ENT Institute and Otorhinolaryngology Department, Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, 200031, China; Institute of Biomedical Sciences, Fudan University, Shanghai, 200032, China; The Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China; Shanghai Engineering Research Centre of Cochlear Implant, Shanghai, 200031, China.
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22
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Kroll J, Jaime Tobón LM, Vogl C, Neef J, Kondratiuk I, König M, Strenzke N, Wichmann C, Milosevic I, Moser T. Endophilin-A regulates presynaptic Ca 2+ influx and synaptic vesicle recycling in auditory hair cells. EMBO J 2019; 38:e100116. [PMID: 30733243 PMCID: PMC6396150 DOI: 10.15252/embj.2018100116] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 12/17/2018] [Accepted: 12/20/2018] [Indexed: 12/20/2022] Open
Abstract
Ribbon synapses of cochlear inner hair cells (IHCs) operate with high rates of neurotransmission; yet, the molecular regulation of synaptic vesicle (SV) recycling at these synapses remains poorly understood. Here, we studied the role of endophilins-A1-3, endocytic adaptors with curvature-sensing and curvature-generating properties, in mouse IHCs. Single-cell RT-PCR indicated the expression of endophilins-A1-3 in IHCs, and immunoblotting confirmed the presence of endophilin-A1 and endophilin-A2 in the cochlea. Patch-clamp recordings from endophilin-A-deficient IHCs revealed a reduction of Ca2+ influx and exocytosis, which we attribute to a decreased abundance of presynaptic Ca2+ channels and impaired SV replenishment. Slow endocytic membrane retrieval, thought to reflect clathrin-mediated endocytosis, was impaired. Otoferlin, essential for IHC exocytosis, co-immunoprecipitated with purified endophilin-A1 protein, suggestive of a molecular interaction that might aid exocytosis-endocytosis coupling. Electron microscopy revealed lower SV numbers, but an increased occurrence of coated structures and endosome-like vacuoles at IHC active zones. In summary, endophilins regulate Ca2+ influx and promote SV recycling in IHCs, likely via coupling exocytosis to endocytosis, and contributing to membrane retrieval and SV reformation.
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Affiliation(s)
- Jana Kroll
- Synaptic Vesicle Dynamics Group, European Neuroscience Institute (ENI), University Medical Center Göttingen, Göttingen, Germany
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience, InnerEarLab and Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Göttingen Graduate School for Neuroscience and Molecular Biosciences, University of Göttingen, Göttingen, Germany
| | - Lina M Jaime Tobón
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Göttingen Graduate School for Neuroscience and Molecular Biosciences, University of Göttingen, Göttingen, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany
| | - Christian Vogl
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany
- Presynaptogenesis and Intracellular Transport in Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Jakob Neef
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany
| | - Ilona Kondratiuk
- Synaptic Vesicle Dynamics Group, European Neuroscience Institute (ENI), University Medical Center Göttingen, Göttingen, Germany
| | - Melanie König
- Synaptic Vesicle Dynamics Group, European Neuroscience Institute (ENI), University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Nicola Strenzke
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany
- Auditory Systems Physiology Group and InnerEarLab, Department of Otolaryngology, University of Göttingen Medical Center, Göttingen, Germany
| | - Carolin Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience, InnerEarLab and Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany
| | - Ira Milosevic
- Synaptic Vesicle Dynamics Group, European Neuroscience Institute (ENI), University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Tobias Moser
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany
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23
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Pangrsic T, Vogl C. Balancing presynaptic release and endocytic membrane retrieval at hair cell ribbon synapses. FEBS Lett 2018; 592:3633-3650. [PMID: 30251250 DOI: 10.1002/1873-3468.13258] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 09/18/2018] [Accepted: 09/19/2018] [Indexed: 11/07/2022]
Abstract
The timely and reliable processing of auditory and vestibular information within the inner ear requires highly sophisticated sensory transduction pathways. On a cellular level, these demands are met by hair cells, which respond to sound waves - or alterations in body positioning - by releasing glutamate-filled synaptic vesicles (SVs) from their presynaptic active zones with unprecedented speed and exquisite temporal fidelity, thereby initiating the auditory and vestibular pathways. In order to achieve this, hair cells have developed anatomical and molecular specializations, such as the characteristic and name-giving 'synaptic ribbons' - presynaptically anchored dense bodies that tether SVs prior to release - as well as other unique or unconventional synaptic proteins. The tightly orchestrated interplay between these molecular components enables not only ultrafast exocytosis, but similarly rapid and efficient compensatory endocytosis. So far, the knowledge of how endocytosis operates at hair cell ribbon synapses is limited. In this Review, we summarize recent advances in our understanding of the SV cycle and molecular anatomy of hair cell ribbon synapses, with a focus on cochlear inner hair cells.
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Affiliation(s)
- Tina Pangrsic
- Synaptic Physiology of Mammalian Vestibular Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine, University Medical Center Göttingen, Germany
| | - Christian Vogl
- Presynaptogenesis and Intracellular Transport in Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine, University Medical Center Göttingen, Germany
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24
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Mechanotransduction is required for establishing and maintaining mature inner hair cells and regulating efferent innervation. Nat Commun 2018; 9:4015. [PMID: 30275467 PMCID: PMC6167318 DOI: 10.1038/s41467-018-06307-w] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 08/21/2018] [Indexed: 12/13/2022] Open
Abstract
In the adult auditory organ, mechanoelectrical transducer (MET) channels are essential for transducing acoustic stimuli into electrical signals. In the absence of incoming sound, a fraction of the MET channels on top of the sensory hair cells are open, resulting in a sustained depolarizing current. By genetically manipulating the in vivo expression of molecular components of the MET apparatus, we show that during pre-hearing stages the MET current is essential for establishing the electrophysiological properties of mature inner hair cells (IHCs). If the MET current is abolished in adult IHCs, they revert into cells showing electrical and morphological features characteristic of pre-hearing IHCs, including the re-establishment of cholinergic efferent innervation. The MET current is thus critical for the maintenance of the functional properties of adult IHCs, implying a degree of plasticity in the mature auditory system in response to the absence of normal transduction of acoustic signals. Mechanoelectrical transducer (MET) channels on the tips of inner hair cells are essential for transducing auditory sensory information. Here, the authors show that disrupting MET channel function also prevents the preservation of normal inner hair cell identity in adult mice.
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25
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Spatiotemporal coordination of cellular differentiation and tissue morphogenesis in organ of Corti development. Med Mol Morphol 2018. [PMID: 29536272 DOI: 10.1007/s00795-018-0185-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The organ of Corti, an acoustic sensory organ, is a specifically differentiated epithelium of the cochlear duct, which is a part of the membranous labyrinth in the inner ear. Cells in the organ of Corti are generally classified into two kinds; hair cells, which transduce the mechanical stimuli of sound to the cell membrane electrical potential differences, and supporting cells. These cells emerge from homogeneous prosensory epithelium through cell fate determination and differentiation. In the organ of Corti organogenesis, cell differentiation and the rearrangement of their position proceed in parallel, resulting in a characteristic alignment of mature hair cells and supporting cells. Recently, studies have focused on the signaling molecules and transcription factors that regulate cell fate determination and differentiation processes. In comparison, less is known about the mechanism of the formation of the tissue architecture; however, this is important in the morphogenesis of the organ of Corti. Thus, this review will introduce previous findings that focus on how cell fate determination, cell differentiation, and whole tissue morphogenesis proceed in a spatiotemporally and finely coordinated manner. This overview provides an insight into the regulatory mechanisms of the coordination in the developing organ of Corti.
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26
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Wu JS, Vyas P, Glowatzki E, Fuchs PA. Opposing expression gradients of calcitonin-related polypeptide alpha (Calca/Cgrpα) and tyrosine hydroxylase (Th) in type II afferent neurons of the mouse cochlea. J Comp Neurol 2017; 526:425-438. [PMID: 29055051 DOI: 10.1002/cne.24341] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 10/04/2017] [Accepted: 10/10/2017] [Indexed: 12/20/2022]
Abstract
Type II spiral ganglion neurons (SGNs) are small caliber, unmyelinated afferents that extend dendritic arbors hundreds of microns along the cochlear spiral, contacting many outer hair cells (OHCs). Despite these many contacts, type II afferents are insensitive to sound and only weakly depolarized by glutamate release from OHCs. Recent studies suggest that type II afferents may be cochlear nociceptors, and can be excited by ATP released during tissue damage, by analogy to somatic pain-sensing C-fibers. The present work compares the expression patterns among cochlear type II afferents of two genes found in C-fibers: calcitonin-related polypeptide alpha (Calca/Cgrpα), specific to pain-sensing C-fibers, and tyrosine hydroxylase (Th), specific to low-threshold mechanoreceptive C-fibers, which was shown previously to be a selective biomarker of type II versus type I cochlear afferents (Vyas et al., ). Whole-mount cochlear preparations from 3-week- to 2-month-old CGRPα-EGFP (GENSAT) mice showed expression of Cgrpα in a subset of SGNs with type II-like peripheral dendrites extending beneath OHCs. Double labeling with other molecular markers confirmed that the labeled SGNs were neither type I SGNs nor olivocochlear efferents. Cgrpα starts to express in type II SGNs before hearing onset, but the expression level declines in the adult. The expression patterns of Cgrpα and Th formed opposing gradients, with Th being preferentially expressed in apical and Cgrpα in basal type II afferent neurons, indicating heterogeneity among type II afferent neurons. The expression of Th and Cgrpα was not mutually exclusive and co-expression could be observed, most abundantly in the middle cochlear turn.
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Affiliation(s)
- Jingjing Sherry Wu
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland.,The Center for Hearing and Balance and the Center for Sensory Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Pankhuri Vyas
- The Center for Hearing and Balance and the Center for Sensory Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland.,Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Elisabeth Glowatzki
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland.,The Center for Hearing and Balance and the Center for Sensory Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland.,Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Paul Albert Fuchs
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland.,The Center for Hearing and Balance and the Center for Sensory Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland.,Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland
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27
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Meese S, Cepeda AP, Gahlen F, Adams CM, Ficner R, Ricci AJ, Heller S, Reisinger E, Herget M. Activity-Dependent Phosphorylation by CaMKIIδ Alters the Ca 2+ Affinity of the Multi-C 2-Domain Protein Otoferlin. Front Synaptic Neurosci 2017; 9:13. [PMID: 29046633 PMCID: PMC5632675 DOI: 10.3389/fnsyn.2017.00013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 09/11/2017] [Indexed: 01/20/2023] Open
Abstract
Otoferlin is essential for fast Ca2+-triggered transmitter release from auditory inner hair cells (IHCs), playing key roles in synaptic vesicle release, replenishment and retrieval. Dysfunction of otoferlin results in profound prelingual deafness. Despite its crucial role in cochlear synaptic processes, mechanisms regulating otoferlin activity have not been studied to date. Here, we identified Ca2+/calmodulin-dependent serine/threonine kinase II delta (CaMKIIδ) as an otoferlin binding partner by pull-downs from chicken utricles and reassured interaction by a co-immunoprecipitation with heterologously expressed proteins in HEK cells. We confirmed the expression of CaMKIIδ in rodent IHCs by immunohistochemistry and real-time PCR. A proximity ligation assay indicates close proximity of the two proteins in rat IHCs, suggesting that otoferlin and CaMKIIδ also interact in mammalian IHCs. In vitro phosphorylation of otoferlin by CaMKIIδ revealed ten phosphorylation sites, five of which are located within C2-domains. Exchange of serines/threonines at phosphorylated sites into phosphomimetic aspartates reduces the Ca2+ affinity of the recombinant C2F domain 10-fold, and increases the Ca2+ affinity of the C2C domain. Concordantly, we show that phosphorylation of otoferlin and/or its interaction partners are enhanced upon hair cell depolarization and blocked by pharmacological CaMKII inhibition. We therefore propose that otoferlin activity is regulated by CaMKIIδ in IHCs.
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Affiliation(s)
- Sandra Meese
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, and Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.,Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences, Göttingen, Germany
| | - Andreia P Cepeda
- Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences, Göttingen, Germany.,Molecular Biology of Cochlear Neurotransmission Group, Department of Otorhinolaryngology, University Medical Center Göttingen, and Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Felix Gahlen
- Department of Otorhinolaryngology, Head and Neck Surgery, Ruhr-University Bochum, Bochum, Germany
| | - Christopher M Adams
- Stanford University Mass Spectrometry, Stanford University, Stanford, CA, United States
| | - Ralf Ficner
- Department of Molecular Structural Biology, Institute for Microbiology and Genetics, and Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Anthony J Ricci
- Department of Otolaryngology, Head and Neck Surgery, Stanford School of Medicine, Stanford, CA, United States
| | - Stefan Heller
- Department of Otolaryngology, Head and Neck Surgery, Stanford School of Medicine, Stanford, CA, United States
| | - Ellen Reisinger
- Molecular Biology of Cochlear Neurotransmission Group, Department of Otorhinolaryngology, University Medical Center Göttingen, and Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Meike Herget
- Department of Otolaryngology, Head and Neck Surgery, Stanford School of Medicine, Stanford, CA, United States
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28
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Local gene therapy durably restores vestibular function in a mouse model of Usher syndrome type 1G. Proc Natl Acad Sci U S A 2017; 114:9695-9700. [PMID: 28835534 DOI: 10.1073/pnas.1708894114] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Our understanding of the mechanisms underlying inherited forms of inner ear deficits has considerably improved during the past 20 y, but we are still far from curative treatments. We investigated gene replacement as a strategy for restoring inner ear functions in a mouse model of Usher syndrome type 1G, characterized by congenital profound deafness and balance disorders. These mice lack the scaffold protein sans, which is involved both in the morphogenesis of the stereociliary bundle, the sensory antenna of inner ear hair cells, and in the mechanoelectrical transduction process. We show that a single delivery of the sans cDNA by the adenoassociated virus 8 to the inner ear of newborn mutant mice reestablishes the expression and targeting of the protein to the tips of stereocilia. The therapeutic gene restores the architecture and mechanosensitivity of stereociliary bundles, improves hearing thresholds, and durably rescues these mice from the balance defects. Our results open up new perspectives for efficient gene therapy of cochlear and vestibular disorders by showing that even severe dysmorphogenesis of stereociliary bundles can be corrected.
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29
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Connexin-Mediated Signaling in Nonsensory Cells Is Crucial for the Development of Sensory Inner Hair Cells in the Mouse Cochlea. J Neurosci 2017; 37:258-268. [PMID: 28077706 PMCID: PMC5242392 DOI: 10.1523/jneurosci.2251-16.2016] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 10/10/2016] [Accepted: 11/07/2016] [Indexed: 12/03/2022] Open
Abstract
Mutations in the genes encoding for gap junction proteins connexin 26 (Cx26) and connexin 30 (Cx30) have been linked to syndromic and nonsyndromic hearing loss in mice and humans. The release of ATP from connexin hemichannels in cochlear nonsensory cells has been proposed to be the main trigger for action potential activity in immature sensory inner hair cells (IHCs), which is crucial for the refinement of the developing auditory circuitry. Using connexin knock-out mice, we show that IHCs fire spontaneous action potentials even in the absence of ATP-dependent intercellular Ca2+ signaling in the nonsensory cells. However, this signaling from nonsensory cells was able to increase the intrinsic IHC firing frequency. We also found that connexin expression is key to IHC functional maturation. In Cx26 conditional knock-out mice (Cx26Sox10-Cre), the maturation of IHCs, which normally occurs at approximately postnatal day 12, was partially prevented. Although Cx30 has been shown not to be required for hearing in young adult mice, IHCs from Cx30 knock-out mice exhibited a comprehensive brake in their development, such that their basolateral membrane currents and synaptic machinery retain a prehearing phenotype. We propose that IHC functional differentiation into mature sensory receptors is initiated in the prehearing cochlea provided that the expression of either connexin reaches a threshold level. As such, connexins regulate one of the most crucial functional refinements in the mammalian cochlea, the disruption of which contributes to the deafness phenotype observed in mice and DFNB1 patients. SIGNIFICANCE STATEMENT The correct development and function of the mammalian cochlea relies not only on the sensory hair cells, but also on the surrounding nonsensory cells. Although the nonsensory cells have been largely implicated in the general homeostasis in the mature cochlea, their involvement in the initial functional differentiation of the sensory inner hair cells is less clear. Using mutant mouse models for the most common form of congenital deafness in humans, which are knock-outs for the gap-junction channels connexin 26 and connexin 30 genes, we show that defects in nonsensory cells prevented the functional maturation of inner hair cells. In connexin knock-outs, inner hair cells remained stuck at a prehearing stage of development and, as such, are unable to process sound information.
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30
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Afferent synaptogenesis between ectopic hair-cell-like cells and neurites of spiral ganglion induced by Atoh1 in mammals in vitro. Neuroscience 2017; 357:185-196. [PMID: 28576729 DOI: 10.1016/j.neuroscience.2017.05.040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 05/20/2017] [Accepted: 05/23/2017] [Indexed: 11/20/2022]
Abstract
Newly formed ectopic hair-cell-like cells (EHCLCs) induced by overexpression of atonal homolog 1 (Atoh1) in vitro were found to possess features of endogenous hair cells (HCs) in previous reports and in the present study. However, limited information is available regarding whether EHCLCs and native spiral ganglion neurons (SGNs) form afferent synapses, which are important for the restoration of hearing. In the current study, we focused on the afferent synaptogenesis between EHCLCs and SGN-derived dendrites. Cochlear explants of auditory epithelia with native SGNs retained were cultured in vitro, and human adenovirus serotype 5 (Ad5) vectors encoding Atoh1 were used to overexpress Atoh1 and induce EHCLCs. We observed that the neurites of the original SGNs extended toward the lesser epithelial ridge (LER) and innervated the EHCLCs. Immunohistochemical analyses revealed the expression of presynaptic ribbon C-terminal-binding protein 2 (CtBP2) and postsynaptic density protein (PSD)-95 in the nerve endings of SGN-derived neurons adjacent to EHCLCs. PSD-95 was located directly opposite CtBP2-positive puncta in the terminals of branches of SGNs, demonstrating that the neurites of SGNs formed afferent-like synaptic connections with EHCLCs. However, the expression of glutamate receptor type 2 (GluR2) could not be detected in the terminals of branches of SGNs surrounding EHCLCs. In addition, we found that the presynaptic ribbon (CtBP2) formation in EHCLCs preceded neural innervation. Furthermore, CtBP2-positive puncta increased and then decreased in EHCLCs, similar to the changes observed in endogenous HCs in terms of their number and distribution. Our finding of the generation of cochlear afferent synapses between EHCLCs and original SGNs will lay the foundation for regenerative approaches to restoring hearing after hair cell loss.
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31
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Tadenev ALD, Tarchini B. The Spindle Orientation Machinery Beyond Mitosis: When Cell Specialization Demands Polarization. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1002:209-225. [DOI: 10.1007/978-3-319-57127-0_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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32
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Marcotti W, Corns LF, Goodyear RJ, Rzadzinska AK, Avraham KB, Steel KP, Richardson GP, Kros CJ. The acquisition of mechano-electrical transducer current adaptation in auditory hair cells requires myosin VI. J Physiol 2016; 594:3667-81. [PMID: 27111754 PMCID: PMC4929313 DOI: 10.1113/jp272220] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 04/08/2016] [Indexed: 01/06/2023] Open
Abstract
KEY POINTS The transduction of sound into electrical signals occurs at the hair bundles atop sensory hair cells in the cochlea, by means of mechanosensitive ion channels, the mechano-electrical transducer (MET) channels. The MET currents decline during steady stimuli; this is termed adaptation and ensures they always work within the most sensitive part of their operating range, responding best to rapidly changing (sound) stimuli. In this study we used a mouse model (Snell's waltzer) for hereditary deafness in humans that has a mutation in the gene encoding an unconventional myosin, myosin VI, which is present in the hair bundles. We found that in the absence of myosin VI the MET current fails to acquire its characteristic adaptation as the hair bundles develop. We propose that myosin VI supports the acquisition of adaptation by removing key molecules from the hair bundle that serve a temporary, developmental role. ABSTRACT Mutations in Myo6, the gene encoding the (F-actin) minus end-directed unconventional myosin, myosin VI, cause hereditary deafness in mice (Snell's waltzer) and humans. In the sensory hair cells of the cochlea, myosin VI is expressed in the cell bodies and along the stereocilia that project from the cells' apical surface. It is required for maintaining the structural integrity of the mechanosensitive hair bundles formed by the stereocilia. In this study we investigate whether myosin VI contributes to mechano-electrical transduction. We report that Ca(2+) -dependent adaptation of the mechano-electrical transducer (MET) current, which serves to keep the transduction apparatus operating within its most sensitive range, is absent in outer and inner hair cells from homozygous Snell's waltzer mutant mice, which fail to express myosin VI. The operating range of the MET channels is also abnormal in the mutants, resulting in the absence of a resting MET current. We found that cadherin 23, a component of the hair bundle's transient lateral links, fails to be downregulated along the length of the stereocilia in maturing Myo6 mutant mice. MET currents of heterozygous littermates appear normal. We propose that myosin VI, by removing key molecules from developing hair bundles, is required for the development of the MET apparatus and its Ca(2+) -dependent adaptation.
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Affiliation(s)
- Walter Marcotti
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QG, UK.,Department of Biomedical Science, Addison Building, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Laura F Corns
- Department of Biomedical Science, Addison Building, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Richard J Goodyear
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QG, UK
| | | | - Karen B Avraham
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Karen P Steel
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge, CB10 1SA, UK.,Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London, SE1 1UL, UK
| | - Guy P Richardson
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QG, UK
| | - Corné J Kros
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QG, UK.,Department of Otorhinolaryngology, University Medical Center Groningen, University of Groningen, 9700 RB, Groningen, The Netherlands
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Tmc1 Point Mutation Affects Ca2+ Sensitivity and Block by Dihydrostreptomycin of the Mechanoelectrical Transducer Current of Mouse Outer Hair Cells. J Neurosci 2016; 36:336-49. [PMID: 26758827 DOI: 10.1523/jneurosci.2439-15.2016] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED The transduction of sound into electrical signals depends on mechanically sensitive ion channels in the stereociliary bundle. The molecular composition of this mechanoelectrical transducer (MET) channel is not yet known. Transmembrane channel-like protein isoforms 1 (TMC1) and 2 (TMC2) have been proposed to form part of the MET channel, although their exact roles are still unclear. Using Beethoven (Tmc1(Bth/Bth)) mice, which have an M412K point mutation in TMC1 that adds a positive charge, we found that Ca(2+) permeability and conductance of the MET channel of outer hair cells (OHCs) were reduced. Tmc1(Bth/Bth) OHCs were also less sensitive to block by the permeant MET channel blocker dihydrostreptomycin, whether applied extracellularly or intracellularly. These findings suggest that the amino acid that is mutated in Bth is situated at or near the negatively charged binding site for dihydrostreptomycin within the permeation pore of the channel. We also found that the Ca(2+) dependence of the operating range of the MET channel was altered by the M412K mutation. Depolarization did not increase the resting open probability of the MET current of Tmc1(Bth/Bth) OHCs, whereas raising the intracellular concentration of the Ca(2+) chelator BAPTA caused smaller increases in resting open probability in Bth mutant OHCs than in wild-type control cells. We propose that these observations can be explained by the reduced Ca(2+) permeability of the mutated MET channel indirectly causing the Ca(2+) sensor for adaptation, at or near the intracellular face of the MET channel, to become more sensitive to Ca(2+) influx as a compensatory mechanism. SIGNIFICANCE STATEMENT In the auditory system, the hair cells convert sound-induced mechanical movement of the hair bundles atop these cells into electrical signals through the opening of mechanically gated ion channels at the tips of the bundles. Although the nature of these mechanoelectrical transducer (MET) channels is still unclear, recent studies implicate transmembrane channel-like protein isoform 1 (TMC1) channels in the mammalian cochlea. Using a mutant mouse model (Beethoven) for progressive hearing loss in humans (DFNA36), which harbors a point mutation in the Tmc1 gene, we show that this mutation affects the MET channel pore, reducing its Ca(2+) permeability and its affinity for the permeant blocker dihydrostreptomycin. A number of phenomena that we ascribe to Ca(2+)-dependent adaptation appear stronger, in compensation for the reduced Ca(2+) entry.
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Wong EYM, Xu CY, Brahmachary M, Xu PX. A Novel ENU-Induced Mutation in Myo6 Causes Vestibular Dysfunction and Deafness. PLoS One 2016; 11:e0154984. [PMID: 27171474 PMCID: PMC4865150 DOI: 10.1371/journal.pone.0154984] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 04/23/2016] [Indexed: 11/24/2022] Open
Abstract
Mouse N-ethyl-N-nitrosourea (ENU) mutagenesis has generated many useful animal models for human diseases. Here we describe the identification of a novel ENU-induced mouse mutant strain Turner (Tur) that displays circling and headtossing behavior and progressive hearing loss. Tur/Tur homozygous animals lack Preyer and righting reflexes and display severe headtossing and reaching response defect. We mapped the Tur mutation to a critical region of 11 cM on chromosome 9 that includes myosin VI. Direct sequence analysis revealed a c.820A>T substitution in exon 8 of the Myo6 gene that changes amino acid Asn200 to Ile (p.N200I) in the motor domain. Analysis of inner ear hair cells by immunohistochemistry, scanning electron microscopy and histology revealed degeneration of hair cells in the inner ear and structural malformation of the stereocilia in the cochlea of Turner homozygous mutant mice. Our data indicate that this novel mouse strain provides a useful model for future studies on the function of myosin VI in mammalian auditory and non-auditory systems and in human syndromes.
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MESH Headings
- Animals
- Auditory Threshold
- Base Sequence
- Behavior, Animal
- Chromosomes, Mammalian/genetics
- Deafness/genetics
- Deafness/physiopathology
- Epithelium/pathology
- Epithelium/ultrastructure
- Ethylnitrosourea
- Evoked Potentials, Auditory, Brain Stem
- Genes, Dominant
- Hair Cells, Auditory/pathology
- Hair Cells, Auditory/ultrastructure
- Male
- Mice, Inbred C57BL
- Mice, Mutant Strains
- Mutation/genetics
- Myosin Heavy Chains/genetics
- Penetrance
- Vestibule, Labyrinth/physiopathology
- Vestibule, Labyrinth/ultrastructure
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Affiliation(s)
- Elaine Y. M. Wong
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Chelsea Y. Xu
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Manisha Brahmachary
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Pin-Xian Xu
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- * E-mail:
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Tavazzani E, Spaiardi P, Zampini V, Contini D, Manca M, Russo G, Prigioni I, Marcotti W, Masetto S. Distinct roles of Eps8 in the maturation of cochlear and vestibular hair cells. Neuroscience 2016; 328:80-91. [PMID: 27132230 DOI: 10.1016/j.neuroscience.2016.04.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 04/12/2016] [Accepted: 04/24/2016] [Indexed: 11/17/2022]
Abstract
Several genetic mutations affecting the development and function of mammalian hair cells have been shown to cause deafness but not vestibular defects, most likely because vestibular deficits are sometimes centrally compensated. The study of hair cell physiology is thus a powerful direct approach to ascertain the functional status of the vestibular end organs. Deletion of Epidermal growth factor receptor pathway substrate 8 (Eps8), a gene involved in actin remodeling, has been shown to cause deafness in mice. While both inner and outer hair cells from Eps8 knockout (KO) mice showed abnormally short stereocilia, inner hair cells (IHCs) also failed to acquire mature-type ion channels. Despite the fact that Eps8 is also expressed in vestibular hair cells, Eps8 KO mice show no vestibular deficits. In the present study we have investigated the properties of vestibular Type I and Type II hair cells in Eps8-KO mice and compared them to those of cochlear IHCs. In the absence of Eps8, vestibular hair cells show normally long kinocilia, significantly shorter stereocilia and a normal pattern of basolateral voltage-dependent ion channels. We have also found that while vestibular hair cells from Eps8 KO mice show normal voltage responses to injected sinusoidal currents, which were used to mimic the mechanoelectrical transducer current, IHCs lose their ability to synchronize their responses to the stimulus. We conclude that the absence of Eps8 produces a weaker phenotype in vestibular hair cells compared to cochlear IHCs, since it affects the hair bundle morphology but not the basolateral membrane currents. This difference is likely to explain the absence of obvious vestibular dysfunction in Eps8 KO mice.
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Affiliation(s)
- Elisa Tavazzani
- Department of Brain and Behavioral Sciences, University of Pavia, Via Forlanini 6, 27100 Pavia, Italy
| | - Paolo Spaiardi
- Department of Brain and Behavioral Sciences, University of Pavia, Via Forlanini 6, 27100 Pavia, Italy
| | - Valeria Zampini
- Department of Brain and Behavioral Sciences, University of Pavia, Via Forlanini 6, 27100 Pavia, Italy.
| | - Donatella Contini
- Department of Brain and Behavioral Sciences, University of Pavia, Via Forlanini 6, 27100 Pavia, Italy.
| | - Marco Manca
- Department of Brain and Behavioral Sciences, University of Pavia, Via Forlanini 6, 27100 Pavia, Italy
| | - Giancarlo Russo
- Department of Brain and Behavioral Sciences, University of Pavia, Via Forlanini 6, 27100 Pavia, Italy
| | - Ivo Prigioni
- Department of Brain and Behavioral Sciences, University of Pavia, Via Forlanini 6, 27100 Pavia, Italy
| | - Walter Marcotti
- Department of Biomedical Science, Sensory Neuroscience Group, Alfred Denny Building (B1 221), University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
| | - Sergio Masetto
- Department of Brain and Behavioral Sciences, University of Pavia, Via Forlanini 6, 27100 Pavia, Italy.
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Li S, Hang L, Ma Y. FGF22 protects hearing function from gentamycin ototoxicity by maintaining ribbon synapse number. Hear Res 2016; 332:39-45. [DOI: 10.1016/j.heares.2015.11.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 10/13/2015] [Accepted: 11/23/2015] [Indexed: 01/16/2023]
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Cochlear afferent innervation development. Hear Res 2015; 330:157-69. [DOI: 10.1016/j.heares.2015.07.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 06/02/2015] [Accepted: 07/21/2015] [Indexed: 01/11/2023]
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Wichmann C, Moser T. Relating structure and function of inner hair cell ribbon synapses. Cell Tissue Res 2015; 361:95-114. [PMID: 25874597 PMCID: PMC4487357 DOI: 10.1007/s00441-014-2102-7] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 12/18/2014] [Indexed: 01/28/2023]
Abstract
In the mammalian cochlea, sound is encoded at synapses between inner hair cells (IHCs) and type I spiral ganglion neurons (SGNs). Each SGN receives input from a single IHC ribbon-type active zone (AZ) and yet SGNs indefatigably spike up to hundreds of Hz to encode acoustic stimuli with submillisecond precision. Accumulating evidence indicates a highly specialized molecular composition and structure of the presynapse, adapted to suit these high functional demands. However, we are only beginning to understand key features such as stimulus-secretion coupling, exocytosis mechanisms, exo-endocytosis coupling, modes of endocytosis and vesicle reformation, as well as replenishment of the readily releasable pool. Relating structure and function has become an important avenue in addressing these points and has been applied to normal and genetically manipulated hair cell synapses. Here, we review some of the exciting new insights gained from recent studies of the molecular anatomy and physiology of IHC ribbon synapses.
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Affiliation(s)
- C. Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University Medical Center Göttingen, Göttingen, Germany
| | - T. Moser
- Collaborative Research Center 889, University Medical Center Göttingen, Göttingen, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany
- Bernstein Center for Computational Neuroscience, University of Göttingen, Göttingen, Germany
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Otoferlin deficiency in zebrafish results in defects in balance and hearing: rescue of the balance and hearing phenotype with full-length and truncated forms of mouse otoferlin. Mol Cell Biol 2015; 35:1043-54. [PMID: 25582200 DOI: 10.1128/mcb.01439-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Sensory hair cells convert mechanical motion into chemical signals. Otoferlin, a six-C2 domain transmembrane protein linked to deafness in humans, is hypothesized to play a role in exocytosis at hair cell ribbon synapses. To date, however, otoferlin has been studied almost exclusively in mouse models, and no rescue experiments have been reported. Here we describe the phenotype associated with morpholino-induced otoferlin knockdown in zebrafish and report the results of rescue experiments conducted with full-length and truncated forms of otoferlin. We found that expression of otoferlin occurs early in development and is restricted to hair cells and the midbrain. Immunofluorescence microscopy revealed localization to both apical and basolateral regions of hair cells. Knockdown of otoferlin resulted in hearing and balance defects, as well as locomotion deficiencies. Further, otoferlin morphants had uninflated swim bladders. Rescue experiments conducted with mouse otoferlin restored hearing, balance, and inflation of the swim bladder. Remarkably, truncated forms of otoferlin retaining the C-terminal C2F domain also rescued the otoferlin knockdown phenotype, while the individual N-terminal C2A domain did not. We conclude that otoferlin plays an evolutionarily conserved role in vertebrate hearing and that truncated forms of otoferlin can rescue hearing and balance.
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Padmanarayana M, Hams N, Speight LC, Petersson EJ, Mehl RA, Johnson CP. Characterization of the lipid binding properties of Otoferlin reveals specific interactions between PI(4,5)P2 and the C2C and C2F domains. Biochemistry 2014; 53:5023-33. [PMID: 24999532 PMCID: PMC4144714 DOI: 10.1021/bi5004469] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
![]()
Otoferlin
is a transmembrane protein consisting of six C2 domains,
proposed to act as a calcium sensor for exocytosis. Although otoferlin
is believed to bind calcium and lipids, the lipid specificity and
identity of the calcium binding domains are controversial. Further,
it is currently unclear whether the calcium binding affinity of otoferlin
quantitatively matches the maximal intracellular presynaptic calcium
concentrations of ∼30–50 μM known to elicit exocytosis.
To characterize the calcium and lipid binding properties of otoferlin,
we used isothermal titration calorimetry (ITC), liposome sedimentation
assays, and fluorescence spectroscopy. Analysis of ITC data indicates
that with the exception of the C2A domain, the C2 domains of otoferlin
bind multiple calcium ions with moderate (Kd = 25–95 μM) and low affinities (Kd = 400–700 μM) in solution. However, in the presence
of liposomes, the calcium sensitivity of the domains increased by
up to 10-fold. It was also determined that calcium enhanced liposome
binding for domains C2B–C2E, whereas the C2F domain bound liposomes
in a calcium-independent manner. Mutations that abrogate calcium binding
in C2F do not disrupt liposome binding, supporting the conclusion
that the interaction of the C2F domain with phosphatidylserine is
calcium-independent. Further, domains C2C and C2F, not domains C2A,
C2B, C2D, and C2E, bound phosphatidylinositol 4,5-bisphosphate 1,2-dioleoyl-sn-glycero-3-phospho(1′-myoinositol-4′,5′-bisphosphate) [PI(4,5)P2], which preferentially
steered them toward liposomes harboring PI(4,5)P2. Remarkably, lysine
mutations L478A and L480A in C2C selectively weaken the PI(4,5)P2
interaction while leaving phosphatidylserine binding unaffected. Finally,
shifts in the emission spectra of an environmentally sensitive fluorescent
unnatural amino acid indicate that the calcium binding loops of the
C2F domain directly interact with the lipid bilayer of negatively
charged liposomes in a calcium-independent manner. On the basis of
these results, we propose that the C2F and C2C domains of otoferlin
preferentially bind PI(4,5)P2 and that PI(4,5)P2 may serve to target
otoferlin to the presynapse in a calcium-independent manner. This
positioning would facilitate fast calcium-dependent exocytosis at
the hair cell synapse.
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Affiliation(s)
- Murugesh Padmanarayana
- Department of Biochemistry and Biophysics, Oregon State University , Corvallis, Oregon 973331, United States
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Sakuraba M, Murata J, Teruyama R, Kamiya K, Yamaguchi J, Okano H, Uchiyama Y, Ikeda K. Spatiotemporal expression of TRPM4 in the mouse cochlea. J Neurosci Res 2014; 92:1409-18. [PMID: 24840118 DOI: 10.1002/jnr.23410] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 02/26/2014] [Accepted: 04/14/2014] [Indexed: 11/11/2022]
Abstract
The present study was conducted to elucidate the presence of the transient receptor potential cation channel subfamily M member 4, TRPM4, in the mouse inner ear. TRPM4 immunoreactivity (IR) was found in the cell body of inner hair cells (IHCs) in the organ of Corti in the apical side of marginal cells of the stria vascularis, in the apical portion of the dark cells of the vestibule, and in a subset of the type II neurons in the spiral ganglion. Subsequently, changes in the distribution and expression of TRPM4 in the inner ear during embryonic and postnatal developments were also evaluated. Immunohistochemical localization demonstrated that the emergence of the TRPM4-IR in IHCs occurs shortly before the onset of hearing, whereas that in the marginal cells happens earlier, at the time of birth, coinciding with the onset of endolymph formation. Furthermore, semiquantitative real-time PCR assay showed that expressions of TRPM4 in the organ of Corti and in the stria vascularis increased dramatically at the onset of hearing. Because TRPM4 is a Ca(2+) -activated monovalent-selective cation channel, these findings imply that TRPM4 contributes to potassium ion transport, essential for the signal transduction in IHCs and the formation of endolymph by marginal cells.
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Affiliation(s)
- Mayumi Sakuraba
- Department of Otorhinolaryngology, Juntendo University Graduate School of Medicine, Tokyo, Japan
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42
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Morphological and physiological development of auditory synapses. Hear Res 2014; 311:3-16. [PMID: 24508369 DOI: 10.1016/j.heares.2014.01.007] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Revised: 01/13/2014] [Accepted: 01/20/2014] [Indexed: 02/07/2023]
Abstract
Acoustic communication requires gathering, transforming, and interpreting diverse sound cues. To achieve this, all the spatial and temporal features of complex sound stimuli must be captured in the firing patterns of the primary sensory neurons and then accurately transmitted along auditory pathways for additional processing. The mammalian auditory system relies on several synapses with unique properties in order to meet this task: the auditory ribbon synapses, the endbulb of Held, and the calyx of Held. Each of these synapses develops morphological and electrophysiological characteristics that enable the remarkably precise signal transmission necessary for conveying the miniscule differences in timing that underly sound localization. In this article, we review the current knowledge of how these synapses develop and mature to acquire the specialized features necessary for the sense of hearing.
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Ramakrishnan NA, Drescher MJ, Morley BJ, Kelley PM, Drescher DG. Calcium regulates molecular interactions of otoferlin with soluble NSF attachment protein receptor (SNARE) proteins required for hair cell exocytosis. J Biol Chem 2014; 289:8750-66. [PMID: 24478316 DOI: 10.1074/jbc.m113.480533] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mutations in otoferlin, a C2 domain-containing ferlin family protein, cause non-syndromic hearing loss in humans (DFNB9 deafness). Furthermore, transmitter secretion of cochlear inner hair cells is compromised in mice lacking otoferlin. In the present study, we show that the C2F domain of otoferlin directly binds calcium (KD = 267 μM) with diminished binding in a pachanga (D1767G) C2F mouse mutation. Calcium was found to differentially regulate binding of otoferlin C2 domains to target SNARE (t-SNARE) proteins and phospholipids. C2D-F domains interact with the syntaxin-1 t-SNARE motif with maximum binding within the range of 20-50 μM Ca(2+). At 20 μM Ca(2+), the dissociation rate was substantially lower, indicating increased binding (KD = ∼10(-9)) compared with 0 μM Ca(2+) (KD = ∼10(-8)), suggesting a calcium-mediated stabilization of the C2 domain·t-SNARE complex. C2A and C2B interactions with t-SNAREs were insensitive to calcium. The C2F domain directly binds the t-SNARE SNAP-25 maximally at 100 μM and with reduction at 0 μM Ca(2+), a pattern repeated for C2F domain interactions with phosphatidylinositol 4,5-bisphosphate. In contrast, C2F did not bind the vesicle SNARE protein synaptobrevin-1 (VAMP-1). Moreover, an antibody targeting otoferlin immunoprecipitated syntaxin-1 and SNAP-25 but not synaptobrevin-1. As opposed to an increase in binding with increased calcium, interactions between otoferlin C2F domain and intramolecular C2 domains occurred in the absence of calcium, consistent with intra-C2 domain interactions forming a "closed" tertiary structure at low calcium that "opens" as calcium increases. These results suggest a direct role for otoferlin in exocytosis and modulation of calcium-dependent membrane fusion.
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44
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Myosin motors at neuronal synapses: drivers of membrane transport and actin dynamics. Nat Rev Neurosci 2013; 14:233-47. [DOI: 10.1038/nrn3445] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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45
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Williams LH, Miller KA, Dahl HHM, Manji SSM. Characterization of a novel ENU-generated myosin VI mutant mouse strain with congenital deafness and vestibular dysfunction. Hear Res 2013; 299:53-62. [PMID: 23485424 DOI: 10.1016/j.heares.2013.02.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 02/12/2013] [Accepted: 02/15/2013] [Indexed: 11/30/2022]
Abstract
Myosin VI (Myo6) is known to play an important role in the mammalian auditory and vestibular systems. We have identified a novel N-ethyl-N-nitrosourea mutagenised mouse strain, charlie, carrying an intronic Myo6 splice site mutation. This mutation (IVS5+5G > A) results in skipping of exon 5, and is predicted to cause a frameshift and premature termination of the protein. We detected essentially no Myo6 transcript in tissue from charlie homozygous mutant mice (Myo6(chl/chl)). Myo6(chl/chl) mice exhibit vestibular dysfunction and profound hearing impairment when first tested at four weeks of age. Analysis of vestibular and cochlear hair cells by scanning electron microscopy and immunohistochemistry revealed highly disorganised hair bundles with irregular orientation and kinocilium position at postnatal stage P2-P3. Within a few weeks, the majority of hair cell stereocilia are missing, or fused and elongated, and degeneration of the sensory epithelium occurs. This novel mouse strain will be an important resource in elucidating the role myosin VI plays in the mammalian auditory system, as well as its non-auditory functions.
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Affiliation(s)
- Louise H Williams
- Genetic Hearing Research Laboratory, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia.
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46
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Progressive hereditary hearing impairment caused by a MYO6 mutation resembles presbyacusis. Hear Res 2013; 299:88-98. [PMID: 23340379 DOI: 10.1016/j.heares.2012.12.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 12/18/2012] [Accepted: 12/22/2012] [Indexed: 02/02/2023]
Abstract
Since deafness is the most common sensorineural disorder in humans, better understanding of the underlying causes is necessary to improve counseling and rehabilitation. A Dutch family with autosomal dominantly inherited sensorineural hearing loss was clinically and genetically assessed. The MYO6 gene was selected to be sequenced because of similarities with other, previously described DFNA22 phenotypes and a pathogenic c.3610C > T (p.R1204W) mutation was found to co-segregate with the disease. This missense mutation results in a flat configured audiogram with a mild hearing loss, which becomes severe to profound and gently to steeply downsloping later in life. The age-related typical audiograms (ARTA) constructed for this family resemble presbyacusis. Speech audiometry and results of loudness scaling support the hypothesis that the phenotype of this specific MYO6 mutation mimics presbyacusis.
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Volk AE, Lang-Roth R, Yigit G, Borck G, Nuernberg G, Rosenkranz S, Nuernberg P, Kubisch C, Beutner D. A Novel MYO6 Splice Site Mutation Causes Autosomal Dominant Sensorineural Hearing Loss Type DFNA22 with a Favourable Outcome after Cochlear Implantation. ACTA ACUST UNITED AC 2013; 18:192-9. [DOI: 10.1159/000350246] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 02/25/2013] [Indexed: 11/19/2022]
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Molina L, Fasquelle L, Nouvian R, Salvetat N, Scott HS, Guipponi M, Molina F, Puel JL, Delprat B. Tmprss3 loss of function impairs cochlear inner hair cell Kcnma1 channel membrane expression. Hum Mol Genet 2012; 22:1289-99. [PMID: 23255163 DOI: 10.1093/hmg/dds532] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Before acquiring their mature state, cochlear hair cells undergo a series of changes in expression of ion channels. How this complex mechanism is achieved is not fully understood. Tmprss3, a type II serine protease expressed in hair cells, is required for their proper functioning at the onset of hearing. To unravel the role of Tmprss3 in the acquisition of mature K(+) currents, we compared their function by patch-clamp technique in wild-type Tmprss3(WT) and Tmprss3(Y260X)-mutant mice. Interestingly, only outward K(+) currents were altered in Tmprss3(Y260X)-mutant mice. To determine by which mechanism this occurred, we compared the protein network of Tmprss3(WT) and Tmprss3(Y260X)-mutant mice using proteomic analysis. This led to the identification of a pathway related to potassium Kcnma1 channels. This pathway was validated by immunohistochemistry, focusing on the most downregulated protein that was identified as a cochlear Kcnma1-associated protein, APOA1. Finally, we show that, in contrast to Tmprss3(WT), Kcnma1 channels were absent at the neck of inner hair cells (IHCs) in Tmprss3(Y260X)-mutant mice. In conclusion, our data suggest that lack of Tmprss3 leads to a decrease in Kcnma1 potassium channels expression in (IHCs).
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Affiliation(s)
- Laurence Molina
- SysDiag UMR 3145 CNRS/Bio-Rad, Cap Delta/Parc Euromédecine, 1682 rue de la Valsière, Cedex 4,Montpellier, France
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Safieddine S, El-Amraoui A, Petit C. The auditory hair cell ribbon synapse: from assembly to function. Annu Rev Neurosci 2012; 35:509-28. [PMID: 22715884 DOI: 10.1146/annurev-neuro-061010-113705] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cochlear inner hair cells (IHCs), the mammalian auditory sensory cells, encode acoustic signals with high fidelity by Graded variations of their membrane potential trigger rapid and sustained vesicle exocytosis at their ribbon synapses. The kinetics of glutamate release allows proper transfer of sound information to the primary afferent auditory neurons. Understanding the physiological properties and underlying molecular mechanisms of the IHC synaptic machinery, and especially its high temporal acuity, which is pivotal to speech perception, is a central issue of auditory science. During the past decade, substantial progress in high-resolution imaging and electrophysiological recordings, as well as the development of genetic approaches both in humans and in mice, has produced major insights regarding the morphological, physiological, and molecular characteristics of this synapse. Here we review this recent knowledge and discuss how it enlightens the way the IHC ribbon synapse develops and functions.
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Affiliation(s)
- Saaid Safieddine
- Institut Pasteur, Unité de Génétique et Physiologie de l'Audition, F75015, Paris, France.
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Otoferlin: a multi-C2 domain protein essential for hearing. Trends Neurosci 2012; 35:671-80. [DOI: 10.1016/j.tins.2012.08.002] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 07/25/2012] [Accepted: 08/13/2012] [Indexed: 12/21/2022]
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