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Xu K, Xiao Y, Luo J, Chao X, Wang R, Fan Z, Wang H, Xu L. Research progress on incomplete partition type 3 inner ear malformation. Eur Arch Otorhinolaryngol 2024; 281:3943-3948. [PMID: 38498189 PMCID: PMC11266284 DOI: 10.1007/s00405-024-08555-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Accepted: 02/12/2024] [Indexed: 03/20/2024]
Abstract
PURPOSE This review aims to provides a comprehensive overview of the latest research progress on IP-III inner ear malformation, focusing on its geneticbasis, imaging features, cochlear implantation, and outcome. METHODS Review the literature on clinical and genetic mechanisms associated with IP-III. RESULTS Mutations in the POU3F4 gene emerge as the principal pathogenic contributors to IP-III anomalies, primarily manifesting through inner ear potential irregularities leading to deafness. While cochlear implantation stands as the primary intervention for restoring hearing, the unique nature of the inner ear anomaly escalates the complexity of surgical procedures and postoperative results. Hence, meticulous preoperative assessment to ascertain surgical feasibility and postoperative verification of electrode placement are imperative. Additionally, gene therapy holds promise as a prospective treatment modality. CONCLUSIONS IP-III denotes X-linked recessive hereditary deafness, with cochlear implantation currently serving as the predominant therapeutic approach. Clinicians are tasked with preoperative assement and individualized postoperative rehabilitation.
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Affiliation(s)
- Kaifan Xu
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial ENT Hospital, Shandong University, Jinan, China
- Department of Auditory Implantology, Second People's Hospital of Shandong Province, jinan, China
- Shandong Institute of Otorhinolaryngology, jinan, China
| | - Yun Xiao
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial ENT Hospital, Shandong University, Jinan, China
- Shandong Institute of Otorhinolaryngology, jinan, China
| | - Jianfen Luo
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial ENT Hospital, Shandong University, Jinan, China
- Department of Auditory Implantology, Second People's Hospital of Shandong Province, jinan, China
| | - Xiuhua Chao
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial ENT Hospital, Shandong University, Jinan, China
- Department of Auditory Implantology, Second People's Hospital of Shandong Province, jinan, China
| | - Ruijie Wang
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial ENT Hospital, Shandong University, Jinan, China
- Department of Auditory Implantology, Second People's Hospital of Shandong Province, jinan, China
| | - Zhaoming Fan
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial ENT Hospital, Shandong University, Jinan, China
| | - Haibo Wang
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial ENT Hospital, Shandong University, Jinan, China
| | - Lei Xu
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial ENT Hospital, Shandong University, Jinan, China.
- Department of Auditory Implantology, Second People's Hospital of Shandong Province, jinan, China.
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Zhang B, Hu Y, Du H, Han S, Ren L, Cheng H, Wang Y, Gao X, Zheng S, Cui Q, Tian L, Liu T, Sun J, Chai R. Tissue engineering strategies for spiral ganglion neuron protection and regeneration. J Nanobiotechnology 2024; 22:458. [PMID: 39085923 PMCID: PMC11293049 DOI: 10.1186/s12951-024-02742-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 07/25/2024] [Indexed: 08/02/2024] Open
Abstract
Cochlear implants can directly activate the auditory system's primary sensory neurons, the spiral ganglion neurons (SGNs), via circumvention of defective cochlear hair cells. This bypass restores auditory input to the brainstem. SGN loss etiologies are complex, with limited mammalian regeneration. Protecting and revitalizing SGN is critical. Tissue engineering offers a novel therapeutic strategy, utilizing seed cells, biomolecules, and scaffold materials to create a cellular environment and regulate molecular cues. This review encapsulates the spectrum of both human and animal research, collating the factors contributing to SGN loss, the latest advancements in the utilization of exogenous stem cells for auditory nerve repair and preservation, the taxonomy and mechanism of action of standard biomolecules, and the architectural components of scaffold materials tailored for the inner ear. Furthermore, we delineate the potential and benefits of the biohybrid neural interface, an incipient technology in the realm of implantable devices. Nonetheless, tissue engineering requires refined cell selection and differentiation protocols for consistent SGN quality. In addition, strategies to improve stem cell survival, scaffold biocompatibility, and molecular cue timing are essential for biohybrid neural interface integration.
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Affiliation(s)
- Bin Zhang
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, 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
| | - Yangnan Hu
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, 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.
| | - Haoliang Du
- Department of Otolaryngology Head and Neck Surgery, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing University, Nanjing, 210008, China
| | - Shanying Han
- Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Lei Ren
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Hong Cheng
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Yusong Wang
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Xin Gao
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Shasha Zheng
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Qingyue Cui
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Lei Tian
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China.
| | - Tingting Liu
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China.
| | - Jiaqiang Sun
- Department of Otolaryngology-Head and Neck Surgery, Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, Anhui, 230001, China.
| | - Renjie Chai
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, 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, 610072, China.
- Department of Neurology, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
- Institute for Stem Cell and Regeneration, Chinese Academy of Science, Beijing, China.
- Southeast University Shenzhen Research Institute, Shenzhen, 518063, China.
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Lou Y, Ma J, Hu Y, Yao X, Liu Y, Wu M, Jia G, Chen Y, Chai R, Xia M, Li W. Integration of Functional Human Auditory Neural Circuits Based on a 3D Carbon Nanotube System. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2309617. [PMID: 38889308 DOI: 10.1002/advs.202309617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 04/27/2024] [Indexed: 06/20/2024]
Abstract
The physiological interactions between the peripheral and central auditory systems are crucial for auditory information transmission and perception, while reliable models for auditory neural circuits are currently lacking. To address this issue, mouse and human neural pathways are generated by utilizing a carbon nanotube nanofiber system. The super-aligned pattern of the scaffold renders the axons of the bipolar and multipolar neurons extending in a parallel direction. In addition, the electrical conductivity of the scaffold maintains the electrophysiological activity of the primary mouse auditory neurons. The mouse and human primary neurons from peripheral and central auditory units in the system are then co-cultured and showed that the two kinds of neurons form synaptic connections. Moreover, neural progenitor cells of the cochlea and auditory cortex are derived from human embryos to generate region-specific organoids and these organoids are assembled in the nanofiber-combined 3D system. Using optogenetic stimulation, calcium imaging, and electrophysiological recording, it is revealed that functional synaptic connections are formed between peripheral neurons and central neurons, as evidenced by calcium spiking and postsynaptic currents. The auditory circuit model will enable the study of the auditory neural pathway and advance the search for treatment strategies for disorders of neuronal connectivity in sensorineural hearing loss.
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Affiliation(s)
- Yiyun Lou
- ENT Institute and Otorhinolaryngology Department of 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
| | - Jiaoyao Ma
- ENT Institute and Otorhinolaryngology Department of 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
| | - Yangnan Hu
- State Key Laboratory of Digital Medical Engineering, 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
| | - Xiaoying Yao
- Obstetrics and Gynecology Hospital, Fudan University, Shanghai, 200011, China
| | - Yaoqian Liu
- ENT Institute and Otorhinolaryngology Department of 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
| | - Mingxuan Wu
- ENT Institute and Otorhinolaryngology Department of 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
| | - Gaogan Jia
- ENT Institute and Otorhinolaryngology Department of 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
| | - Yan Chen
- ENT Institute and Otorhinolaryngology Department of 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
| | - Renjie Chai
- State Key Laboratory of Digital Medical Engineering, 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
| | - Mingyu Xia
- ENT Institute and Otorhinolaryngology Department of 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
| | - Wenyan Li
- ENT Institute and Otorhinolaryngology Department of 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
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Lekkos K, Bhuiyan AA, Albloshi AMK, Brooks PM, Coate TM, Lionikas A. Validation of positional candidates Rps6ka6 and Pou3f4 for a locus associated with skeletal muscle mass variability. G3 (BETHESDA, MD.) 2024; 14:jkae046. [PMID: 38577978 PMCID: PMC11075558 DOI: 10.1093/g3journal/jkae046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 02/17/2024] [Indexed: 04/06/2024]
Abstract
Genetic variability significantly contributes to individual differences in skeletal muscle mass; however, the specific genes involved in that process remain elusive. In this study, we examined the role of positional candidates, Rps6ka6 and Pou3f4, of a chromosome X locus, implicated in muscle mass variability in CFW laboratory mice. Histology of hindlimb muscles was studied in CFW male mice carrying the muscle "increasing" allele C (n = 15) or "decreasing" allele T (n = 15) at the peak marker of the locus, rs31308852, and in the Pou3f4y/- and their wild-type male littermates. To study the role of the Rps6ka6 gene, we deleted exon 7 (Rps6ka6-ΔE7) using clustered regularly interspaced palindromic repeats-Cas9 based method in H2Kb myogenic cells creating a severely truncated RSK4 protein. We then tested whether that mutation affected myoblast proliferation, migration, and/or differentiation. The extensor digitorum longus muscle was 7% larger (P < 0.0001) due to 10% more muscle fibers (P = 0.0176) in the carriers of the "increasing" compared with the "decreasing" CFW allele. The number of fibers was reduced by 15% (P = 0.0268) in the slow-twitch soleus but not in the fast-twitch extensor digitorum longus (P = 0.2947) of Pou3f4y/- mice. The proliferation and migration did not differ between the Rps6ka6-ΔE7 and wild-type H2Kb myoblasts. However, indices of differentiation (myosin expression, P < 0.0001; size of myosin-expressing cells, P < 0.0001; and fusion index, P = 0.0013) were significantly reduced in Rps6ka6-ΔE7 cells. This study suggests that the effect of the X chromosome locus on muscle fiber numbers in the fast-twitch extensor digitorum longus is mediated by the Rps6ka6 gene, whereas the Pou3f4 gene affects fiber number in slow-twitch soleus.
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Affiliation(s)
- Konstantinos Lekkos
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Afra A Bhuiyan
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Abdullah M K Albloshi
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen AB25 2ZD, UK
- Department of Anatomy and Histology, School of Medicine, University of Albaha, Alaqiq 65779, Saudi Arabia
| | - Paige M Brooks
- Department of Biology, Georgetown University, Washington, DC 20057, USA
| | - Thomas M Coate
- Department of Biology, Georgetown University, Washington, DC 20057, USA
| | - Arimantas Lionikas
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen AB25 2ZD, UK
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Kim J, Martinez E, Qiu J, Zhouli Ni J, Kwan KY. Chromatin remodeling protein CHD4 regulates axon guidance of spiral ganglion neurons in developing cochlea. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.31.578202. [PMID: 38352369 PMCID: PMC10862897 DOI: 10.1101/2024.01.31.578202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
The chromodomain helicase binding protein 4 (CHD4) is an ATP-dependent chromatin remodeler. De-novo pathogenic variants of CHD4 cause Sifrim-Hitz-Weiss syndrome (SIHIWES). Patients with SIHIWES show delayed development, intellectual disability, facial dysmorphism, and hearing loss. Many cochlear cell types, including spiral ganglion neurons (SGNs), express CHD4. SGNs are the primary afferent neurons that convey sound information from the cochlea, but the function of CHD4 in SGNs is unknown. We employed the Neurog1(Ngn1) CreERT2 Chd4 conditional knockout animals to delete Chd4 in SGNs. SGNs are classified as type I and type II neurons. SGNs lacking CHD4 showed abnormal fasciculation of type I neurons along with improper pathfinding of type II fibers. CHD4 binding to chromatin from immortalized multipotent otic progenitor-derived neurons was used to identify candidate target genes in SGNs. Gene ontology analysis of CHD4 target genes revealed cellular processes involved in axon guidance, axonal fasciculation, and ephrin receptor signaling pathway. We validated increased Epha4 transcripts in SGNs from Chd4 conditional knockout cochleae. The results suggest that CHD4 attenuates the transcription of axon guidance genes to form the stereotypic pattern of SGN peripheral projections. The results implicate epigenetic changes in circuit wiring by modulating axon guidance molecule expression and provide insights into neurodevelopmental diseases.
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Affiliation(s)
- Jihyun Kim
- Keck Center for Collaborative Neuroscience and Stem Cell Research Center, Rutgers University, Piscataway, NJ 08854, USA
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | - Edward Martinez
- Keck Center for Collaborative Neuroscience and Stem Cell Research Center, Rutgers University, Piscataway, NJ 08854, USA
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | - Jingyun Qiu
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | - Julie Zhouli Ni
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Kelvin Y. Kwan
- Keck Center for Collaborative Neuroscience and Stem Cell Research Center, Rutgers University, Piscataway, NJ 08854, USA
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
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Rose KP, Manilla G, Milon B, Zalzman O, Song Y, Coate TM, Hertzano R. Spatially distinct otic mesenchyme cells show molecular and functional heterogeneity patterns before hearing onset. iScience 2023; 26:107769. [PMID: 37720106 PMCID: PMC10502415 DOI: 10.1016/j.isci.2023.107769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 06/29/2023] [Accepted: 08/25/2023] [Indexed: 09/19/2023] Open
Abstract
The cochlea consists of diverse cellular populations working in harmony to convert mechanical stimuli into electrical signals for the perception of sound. Otic mesenchyme cells (OMCs), often considered a homogeneous cell type, are essential for normal cochlear development and hearing. Despite being the most numerous cell type in the developing cochlea, OMCs are poorly understood. OMCs are known to differentiate into spatially and functionally distinct cell types, including fibrocytes of the lateral wall and spiral limbus, modiolar osteoblasts, and specialized tympanic border cells of the basilar membrane. Here, we show that OMCs are transcriptionally and functionally heterogeneous and can be divided into four distinct populations that spatially correspond to OMC-derived cochlear structures. We also show that this heterogeneity and complexity of OMCs commences during early phases of cochlear development. Finally, we describe the cell-cell communication network of the developing cochlea, inferring a major role for OMC in outgoing signaling.
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Affiliation(s)
- Kevin P. Rose
- Neurotology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Gabriella Manilla
- Neurotology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Beatrice Milon
- Neurotology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ori Zalzman
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Yang Song
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Thomas M. Coate
- Department of Biology, Georgetown University, Washington, DC 20007, USA
| | - Ronna Hertzano
- Neurotology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Bernardinelli E, Huber F, Roesch S, Dossena S. Clinical and Molecular Aspects Associated with Defects in the Transcription Factor POU3F4: A Review. Biomedicines 2023; 11:1695. [PMID: 37371790 DOI: 10.3390/biomedicines11061695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 06/07/2023] [Accepted: 06/08/2023] [Indexed: 06/29/2023] Open
Abstract
X-linked deafness (DFNX) is estimated to account for up to 2% of cases of hereditary hearing loss and occurs in both syndromic and non-syndromic forms. POU3F4 is the gene most commonly associated with X-linked deafness (DFNX2, DFN3) and accounts for about 50% of the cases of X-linked non-syndromic hearing loss. This gene codes for a transcription factor of the POU family that plays a major role in the development of the middle and inner ear. The clinical features of POU3F4-related hearing loss include a pathognomonic malformation of the inner ear defined as incomplete partition of the cochlea type 3 (IP-III). Often, a perilymphatic gusher is observed upon stapedectomy during surgery, possibly as a consequence of an incomplete separation of the cochlea from the internal auditory canal. Here we present an overview of the pathogenic gene variants of POU3F4 reported in the literature and discuss the associated clinical features, including hearing loss combined with additional phenotypes such as cognitive and motor developmental delays. Research on the transcriptional targets of POU3F4 in the ear and brain is in its early stages and is expected to greatly advance our understanding of the pathophysiology of POU3F4-linked hearing loss.
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Affiliation(s)
- Emanuele Bernardinelli
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Florian Huber
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Sebastian Roesch
- Department of Otorhinolaryngology, Head and Neck Surgery, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, 5020 Salzburg, Austria
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Stepwise fate conversion of supporting cells to sensory hair cells in the chick auditory epithelium. iScience 2023; 26:106046. [PMID: 36818302 PMCID: PMC9932131 DOI: 10.1016/j.isci.2023.106046] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 12/17/2022] [Accepted: 01/20/2023] [Indexed: 01/26/2023] Open
Abstract
In contrast to mammals, the avian cochlea, specifically the basilar papilla, can regenerate sensory hair cells, which involves fate conversion of supporting cells to hair cells. To determine the mechanisms for converting supporting cells to hair cells, we used single-cell RNA sequencing during hair cell regeneration in explant cultures of chick basilar papillae. We identified dynamic changes in the gene expression of supporting cells, and the pseudotime trajectory analysis demonstrated the stepwise fate conversion from supporting cells to hair cells. Initially, supporting cell identity was erased and transition to the precursor state occurred. A subsequent gain in hair cell identity progressed together with downregulation of precursor-state genes. Transforming growth factor β receptor 1-mediated signaling was involved in induction of the initial step, and its inhibition resulted in suppression of hair cell regeneration. Our data provide new insights for understanding fate conversion from supporting cells to hair cells in avian basilar papillae.
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Cantu-Guerra HL, Papazian MR, Gorsky AL, Alekos NS, Caccavano A, Karagulyan N, Neef J, Vicini S, Moser T, Coate TM. Cochlear hair cell innervation is dependent on a modulatory function of Semaphorin-3A. Dev Dyn 2023; 252:124-144. [PMID: 36284453 PMCID: PMC9812910 DOI: 10.1002/dvdy.548] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 09/20/2022] [Accepted: 10/06/2022] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Proper connectivity between type I spiral ganglion neurons (SGNs) and inner hair cells (IHCs) in the cochlea is necessary for conveying sound information to the brain in mammals. Previous studies have shown that type I SGNs are heterogeneous in form, function and synaptic location on IHCs, but factors controlling their patterns of connectivity are not well understood. RESULTS During development, cochlear supporting cells and SGNs express Semaphorin-3A (SEMA3A), a known axon guidance factor. Mice homozygous for a point mutation that attenuates normal SEMA3A repulsive activity (Sema3aK108N ) show cochleae with grossly normal patterns of IHC innervation. However, genetic sparse labeling and three-dimensional reconstructions of individual SGNs show that cochleae from Sema3aK108N mice lacked the normal synaptic distribution of type I SGNs. Additionally, Sema3aK108N cochleae show a disrupted distribution of GLUA2 postsynaptic patches around the IHCs. The addition of SEMA3A-Fc to postnatal cochleae led to increases in SGN branching, similar to the effects of inhibiting glutamate receptors. Ca2+ imaging studies show that SEMA3A-Fc decreases SGN activity. CONCLUSIONS Contrary to the canonical view of SEMA3A as a guidance ligand, our results suggest SEMA3A may regulate SGN excitability in the cochlea, which may influence the morphology and synaptic arrangement of type I SGNs.
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Affiliation(s)
- Homero L. Cantu-Guerra
- Department of Biology, Georgetown University, Washington,
District of Columbia, USA
- Interdisciplinary Program in Neuroscience, Georgetown
University, Washington, District of Columbia, USA
| | - Michael R. Papazian
- Department of Biology, Georgetown University, Washington,
District of Columbia, USA
| | - Anna L. Gorsky
- Department of Biology, Georgetown University, Washington,
District of Columbia, USA
| | - Nathalie S. Alekos
- Department of Biology, Georgetown University, Washington,
District of Columbia, USA
| | - Adam Caccavano
- Interdisciplinary Program in Neuroscience, Georgetown
University, Washington, District of Columbia, USA
- Department of Pharmacology, Georgetown University School of
Medicine, Washington, District of Columbia, USA
| | - Nare Karagulyan
- Institute for Auditory Neuroscience and InnerEarLab,
University Medical Center, and Auditory Neuroscience & Synaptic Nanophysiology
Group, Max Planck Institute for Multidisciplinary Sciences, and Cluster of
Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of
Excitable Cells” (MBExC), Göttingen, Germany
| | - Jakob Neef
- Institute for Auditory Neuroscience and InnerEarLab,
University Medical Center, and Auditory Neuroscience & Synaptic Nanophysiology
Group, Max Planck Institute for Multidisciplinary Sciences, and Cluster of
Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of
Excitable Cells” (MBExC), Göttingen, Germany
| | - Stefano Vicini
- Interdisciplinary Program in Neuroscience, Georgetown
University, Washington, District of Columbia, USA
- Department of Pharmacology, Georgetown University School of
Medicine, Washington, District of Columbia, USA
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab,
University Medical Center, and Auditory Neuroscience & Synaptic Nanophysiology
Group, Max Planck Institute for Multidisciplinary Sciences, and Cluster of
Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of
Excitable Cells” (MBExC), Göttingen, Germany
| | - Thomas M. Coate
- Department of Biology, Georgetown University, Washington,
District of Columbia, USA
- Interdisciplinary Program in Neuroscience, Georgetown
University, Washington, District of Columbia, USA
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10
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Nomdedeu-Sancho G, Alsina B. Wiring the senses: Factors that regulate peripheral axon pathfinding in sensory systems. Dev Dyn 2023; 252:81-103. [PMID: 35972036 PMCID: PMC10087148 DOI: 10.1002/dvdy.523] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 08/09/2022] [Accepted: 08/12/2022] [Indexed: 01/04/2023] Open
Abstract
Sensory neurons of the head are the ones that transmit the information about the external world to our brain for its processing. Axons from cranial sensory neurons sense different chemoattractant and chemorepulsive molecules during the journey and in the target tissue to establish the precise innervation with brain neurons and/or receptor cells. Here, we aim to unify and summarize the available information regarding molecular mechanisms guiding the different afferent sensory axons of the head. By putting the information together, we find the use of similar guidance cues in different sensory systems but in distinct combinations. In vertebrates, the number of genes in each family of guidance cues has suffered a great expansion in the genome, providing redundancy, and robustness. We also discuss recently published data involving the role of glia and mechanical forces in shaping the axon paths. Finally, we highlight the remaining questions to be addressed in the field.
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Affiliation(s)
- Gemma Nomdedeu-Sancho
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain
| | - Berta Alsina
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain
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11
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Bernardinelli E, Roesch S, Simoni E, Marino A, Rasp G, Astolfi L, Sarikas A, Dossena S. Novel POU3F4 variants identified in patients with inner ear malformations exhibit aberrant cellular distribution and lack of SLC6A20 transcriptional upregulation. Front Mol Neurosci 2022; 15:999833. [PMID: 36245926 PMCID: PMC9558712 DOI: 10.3389/fnmol.2022.999833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 09/13/2022] [Indexed: 11/14/2022] Open
Abstract
Hearing loss (HL) is the most common sensory defect and affects 450 million people worldwide in a disabling form. Pathogenic sequence alterations in the POU3F4 gene, which encodes a transcription factor, are causative of the most common type of X-linked deafness (X-linked deafness type 3, DFN3, DFNX2). POU3F4-related deafness is characterized by a typical inner ear malformation, namely an incomplete partition of the cochlea type 3 (IP3), with or without an enlargement of the vestibular aqueduct (EVA). The pathomechanism underlying POU3F4-related deafness and the corresponding transcriptional targets are largely uncharacterized. Two male patients belonging to a Caucasian cohort with HL and EVA who presented with an IP3 were submitted to genetic analysis. Two novel sequence variants in POU3F4 were identified by Sanger sequencing. In cell-based assays, the corresponding protein variants (p.S74Afs*8 and p.C327*) showed an aberrant expression and subcellular distribution and lack of transcriptional activity. These two protein variants failed to upregulate the transcript levels of the amino acid transporter gene SLC6A20, which was identified as a novel transcriptional target of POU3F4 by RNA sequencing and RT-qPCR. Accordingly, POU3F4 silencing by siRNA resulted in downregulation of SLC6A20 in mouse embryonic fibroblasts. Moreover, we showed for the first time that SLC6A20 is expressed in the mouse cochlea, and co-localized with POU3F4 in the spiral ligament. The findings presented here point to a novel role of amino acid transporters in the inner ear and pave the way for mechanistic studies of POU3F4-related HL.
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Affiliation(s)
- Emanuele Bernardinelli
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Sebastian Roesch
- Department of Otorhinolaryngology, Head and Neck Surgery, Paracelsus Medical University, Salzburg, Austria
| | - Edi Simoni
- Bioacoustic Research Laboratory, Department of Neuroscience, Biomedical Campus Pietro d’Abano, University of Padua, Padua, Italy
| | - Angela Marino
- Department of Chemical, Biological, Pharmaceutical, and Environmental Sciences, University of Messina, Messina, Italy
| | - Gerd Rasp
- Department of Otorhinolaryngology, Head and Neck Surgery, Paracelsus Medical University, Salzburg, Austria
| | - Laura Astolfi
- Bioacoustic Research Laboratory, Department of Neuroscience, Biomedical Campus Pietro d’Abano, University of Padua, Padua, Italy
- Interdepartmental Research Center of International Auditory Processing Project in Venice (I-APPROVE), Department of Neurosciences, University of Padova, Santi Giovanni e Paolo Hospital, ULSS3, Venice, Italy
| | - Antonio Sarikas
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
- *Correspondence: Antonio Sarikas,
| | - Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
- Silvia Dossena,
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12
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Defourny J. Considering gene therapy to protect from X-linked deafness DFNX2 and associated neurodevelopmental disorders. IBRAIN 2022; 8:431-441. [PMID: 37786584 PMCID: PMC10529175 DOI: 10.1002/ibra.12068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 08/10/2022] [Accepted: 09/13/2022] [Indexed: 10/04/2023]
Abstract
Mutations and deletions in the gene or upstream of the gene encoding the POU3F4 transcription factor cause X-linked progressive deafness DFNX2 and additional neurodevelopmental disorders in humans. Hearing loss can be purely sensorineural or mixed, that is, with both conductive and sensorineural components. Affected males show anatomical abnormalities of the inner ear, which are jointly defined as incomplete partition type III. Current approaches to improve hearing and speech skills of DFNX2 patients do not seem to be fully effective. Owing to inner ear malformations, cochlear implantation is surgically difficult and may predispose towards severe complications. Even in cases where implantation is safely performed, hearing and speech outcomes remain highly variable among patients. Mouse models for DFNX2 deafness revealed that sensorineural loss could arise from a dysfunction of spiral ligament fibrocytes in the lateral wall of the cochlea, which leads to reduced endocochlear potential. Highly positive endocochlear potential is critical for sensory hair cell mechanotransduction and hearing. In this context, here, we propose to develop a therapeutic approach in male Pou3f4 -/y mice based on an adeno-associated viral (AAV) vector-mediated gene transfer in cochlear spiral ligament fibrocytes. Among a broad range of AAV vectors, AAV7 was found to show a strong tropism for the spiral ligament. Thus, we suggest that an AAV7-mediated delivery of Pou3f4 complementary DNA in the spiral ligament of Pou3f4 -/y mice could represent an attractive strategy to prevent fibrocyte degeneration and to restore normal cochlear functions and properties, including a positive endocochlear potential, before hearing loss progresses to profound deafness.
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Affiliation(s)
- Jean Defourny
- GIGA‐Neurosciences, Unit of Cell and Tissue BiologyUniversity of Liège, C.H.U. B36LiègeBelgium
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13
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Filova I, Pysanenko K, Tavakoli M, Vochyanova S, Dvorakova M, Bohuslavova R, Smolik O, Fabriciova V, Hrabalova P, Benesova S, Valihrach L, Cerny J, Yamoah EN, Syka J, Fritzsch B, Pavlinkova G. ISL1 is necessary for auditory neuron development and contributes toward tonotopic organization. Proc Natl Acad Sci U S A 2022; 119:e2207433119. [PMID: 36074819 PMCID: PMC9478650 DOI: 10.1073/pnas.2207433119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 08/04/2022] [Indexed: 11/18/2022] Open
Abstract
A cardinal feature of the auditory pathway is frequency selectivity, represented in a tonotopic map from the cochlea to the cortex. The molecular determinants of the auditory frequency map are unknown. Here, we discovered that the transcription factor ISL1 regulates the molecular and cellular features of auditory neurons, including the formation of the spiral ganglion and peripheral and central processes that shape the tonotopic representation of the auditory map. We selectively knocked out Isl1 in auditory neurons using Neurod1Cre strategies. In the absence of Isl1, spiral ganglion neurons migrate into the central cochlea and beyond, and the cochlear wiring is profoundly reduced and disrupted. The central axons of Isl1 mutants lose their topographic projections and segregation at the cochlear nucleus. Transcriptome analysis of spiral ganglion neurons shows that Isl1 regulates neurogenesis, axonogenesis, migration, neurotransmission-related machinery, and synaptic communication patterns. We show that peripheral disorganization in the cochlea affects the physiological properties of hearing in the midbrain and auditory behavior. Surprisingly, auditory processing features are preserved despite the significant hearing impairment, revealing central auditory pathway resilience and plasticity in Isl1 mutant mice. Mutant mice have a reduced acoustic startle reflex, altered prepulse inhibition, and characteristics of compensatory neural hyperactivity centrally. Our findings show that ISL1 is one of the obligatory factors required to sculpt auditory structural and functional tonotopic maps. Still, upon Isl1 deletion, the ensuing central plasticity of the auditory pathway does not suffice to overcome developmentally induced peripheral dysfunction of the cochlea.
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Affiliation(s)
- Iva Filova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Kateryna Pysanenko
- Department of Auditory Neuroscience, Institute of Experimental Medicine Czech Academy of Sciences, 14220 Prague, Czechia
| | - Mitra Tavakoli
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Simona Vochyanova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Martina Dvorakova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Romana Bohuslavova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Ondrej Smolik
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Valeria Fabriciova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Petra Hrabalova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Sarka Benesova
- Laboratory of Gene Expression, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Lukas Valihrach
- Laboratory of Gene Expression, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Jiri Cerny
- Laboratory of Light Microscopy, Institute of Molecular Genetics Czech Academy of Sciences, 14220 Prague, Czechia
| | - Ebenezer N. Yamoah
- Department of Physiology, School of Medicine, University of Nevada, Reno, NV 89557
| | - Josef Syka
- Department of Auditory Neuroscience, Institute of Experimental Medicine Czech Academy of Sciences, 14220 Prague, Czechia
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA 52242-1324
- Department of Otolaryngology, University of Iowa, Iowa City, IA 52242-1324
| | - Gabriela Pavlinkova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
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14
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Petitpré C, Faure L, Uhl P, Fontanet P, Filova I, Pavlinkova G, Adameyko I, Hadjab S, Lallemend F. Single-cell RNA-sequencing analysis of the developing mouse inner ear identifies molecular logic of auditory neuron diversification. Nat Commun 2022; 13:3878. [PMID: 35790771 PMCID: PMC9256748 DOI: 10.1038/s41467-022-31580-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 06/21/2022] [Indexed: 11/08/2022] Open
Abstract
Different types of spiral ganglion neurons (SGNs) are essential for auditory perception by transmitting complex auditory information from hair cells (HCs) to the brain. Here, we use deep, single cell transcriptomics to study the molecular mechanisms that govern their identity and organization in mice. We identify a core set of temporally patterned genes and gene regulatory networks that may contribute to the diversification of SGNs through sequential binary decisions and demonstrate a role for NEUROD1 in driving specification of a Ic-SGN phenotype. We also find that each trajectory of the decision tree is defined by initial co-expression of alternative subtype molecular controls followed by gradual shifts toward cell fate resolution. Finally, analysis of both developing SGN and HC types reveals cell-cell signaling potentially playing a role in the differentiation of SGNs. Our results indicate that SGN identities are drafted prior to birth and reveal molecular principles that shape their differentiation and will facilitate studies of their development, physiology, and dysfunction.
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Affiliation(s)
- Charles Petitpré
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Louis Faure
- Department of Neuroimmunology, Center for Brain Research, Medical University Vienna, 1090, Vienna, Austria
| | - Phoebe Uhl
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Paula Fontanet
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Iva Filova
- Institute of Biotechnology CAS, 25250, Vestec, Czech Republic
| | | | - Igor Adameyko
- Department of Neuroimmunology, Center for Brain Research, Medical University Vienna, 1090, Vienna, Austria
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Saida Hadjab
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
| | - Francois Lallemend
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
- Ming-Wai Lau Centre for Reparative Medicine, Stockholm Node, Karolinska Institutet, Stockholm, Sweden.
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15
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Single-cell transcriptomic landscapes of the otic neuronal lineage at multiple early embryonic ages. Cell Rep 2022; 38:110542. [PMID: 35320729 DOI: 10.1016/j.celrep.2022.110542] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 12/03/2021] [Accepted: 02/25/2022] [Indexed: 11/20/2022] Open
Abstract
Inner ear vestibular and spiral ganglion neurons (VGNs and SGNs) are known to play pivotal roles in balance control and sound detection. However, the molecular mechanisms underlying otic neurogenesis at early embryonic ages have remained unclear. Here, we use single-cell RNA sequencing to reveal the transcriptomes of mouse otic tissues at three embryonic ages, embryonic day 9.5 (E9.5), E11.5, and E13.5, covering proliferating and undifferentiated otic neuroblasts and differentiating VGNs and SGNs. We validate the high quality of our studies by using multiple assays, including genetic fate mapping analysis, and we uncover several genes upregulated in neuroblasts or differentiating VGNs and SGNs, such as Shox2, Myt1, Casz1, and Sall3. Notably, our findings suggest a general cascaded differentiation trajectory during early otic neurogenesis. The comprehensive understanding of early otic neurogenesis provided by our study holds critical implications for both basic and translational research.
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16
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Chen Y, Qiu J, Wu Y, Jia H, Jiang Y, Jiang M, Wang Z, Sheng HB, Hu L, Zhang Z, Wang Z, Li Y, Huang Z, Wu H. Genetic findings of Sanger and nanopore single-molecule sequencing in patients with X-linked hearing loss and incomplete partition type III. Orphanet J Rare Dis 2022; 17:65. [PMID: 35189936 PMCID: PMC8862311 DOI: 10.1186/s13023-022-02235-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 02/06/2022] [Indexed: 12/01/2022] Open
Abstract
Background POU3F4 is the causative gene for X-linked deafness-2 (DFNX2), characterized by incomplete partition type III (IP-III) malformation of the inner ear. The purpose of this study was to investigate the clinical characteristics and molecular findings in IP-III patients by Sanger or nanopore single-molecule sequencing. Methods Diagnosis of IP-III was mainly based on clinical characteristics including radiological and audiological findings. Sanger sequencing of POU3F4 was carried out for these IP-III patients. For those patients with negative results for POU3F4 Sanger sequencing, nanopore long-read single-molecule sequencing was used to identify the possible pathogenic variants. Hearing intervention outcomes of hearing aids (HAs) fitting and cochlear implantation (CI) were also analyzed. Aided pure tone average (PTA) was further compared between two groups of patients according to their different locations of POU3F4 variants: in the exon region or in the upstream region. Results In total, 18 male patients from 14 unrelated families were diagnosed with IP-III. 10 variants were identified in POU3F4 by Sanger sequencing and 6 of these were reported for the first time (p.Gln181*, p.Val215Gly, p.Arg282Gln, p.Gln316*, c.903_912 delins TGCCA and p.Arg205del). Four different deletions that varied from 80 to 486 kb were identified 876–1503 kb upstream of POU3F4 by nanopore long-read single-molecule sequencing. De novo genetic mutations occurred in 21.4% (3/14) of patients with POU3F4 mutations. Among these 18 patients, 7 had bilateral HAs and 10 patients received unilateral CI. The mean aided PTA for HAs and CI users were 41.1 ± 5.18 and 40.3 ± 7.59 dB HL respectively. The mean PTAs for patients with the variants located in the exon and upstream regions were 39.6 ± 6.31 versus 43.0 ± 7.10 dB HL, which presented no significant difference (p = 0.342). Conclusions Among 14 unrelated IP-III patients, 28.6% (4/14) had no definite mutation in exon region of POU3F4. However, possible pathogenic deletions were identified in upstream region of this gene. De novo genetic mutations occurred in 21.4% (3/14) of patients with POU3F4 mutation. There was no significant difference of hearing intervention outcomes between the IP-III patients with variants located in the exon region and in the upstream region. Supplementary Information The online version contains supplementary material available at 10.1186/s13023-022-02235-7.
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17
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Zhang L, Chen S, Sun Y. Mechanism and Prevention of Spiral Ganglion Neuron Degeneration in the Cochlea. Front Cell Neurosci 2022; 15:814891. [PMID: 35069120 PMCID: PMC8766678 DOI: 10.3389/fncel.2021.814891] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 12/09/2021] [Indexed: 12/14/2022] Open
Abstract
Sensorineural hearing loss (SNHL) is one of the most prevalent sensory deficits in humans, and approximately 360 million people worldwide are affected. The current treatment option for severe to profound hearing loss is cochlear implantation (CI), but its treatment efficacy is related to the survival of spiral ganglion neurons (SGNs). SGNs are the primary sensory neurons, transmitting complex acoustic information from hair cells to second-order sensory neurons in the cochlear nucleus. In mammals, SGNs have very limited regeneration ability, and SGN loss causes irreversible hearing loss. In most cases of SNHL, SGN damage is the dominant pathogenesis, and it could be caused by noise exposure, ototoxic drugs, hereditary defects, presbycusis, etc. Tremendous efforts have been made to identify novel treatments to prevent or reverse the damage to SGNs, including gene therapy and stem cell therapy. This review summarizes the major causes and the corresponding mechanisms of SGN loss and the current protection strategies, especially gene therapy and stem cell therapy, to promote the development of new therapeutic methods.
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Affiliation(s)
- Li Zhang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Sen Chen
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- *Correspondence: Yu Sun,
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18
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Hoshino N, Altarshan Y, Alzein A, Fernando AM, Nguyen HT, Majewski EF, Chen VCF, William Rochlin M, Yu WM. Ephrin-A3 is required for tonotopic map precision and auditory functions in the mouse auditory brainstem. J Comp Neurol 2021; 529:3633-3654. [PMID: 34235739 PMCID: PMC8490280 DOI: 10.1002/cne.25213] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 06/22/2021] [Accepted: 07/02/2021] [Indexed: 01/09/2023]
Abstract
Tonotopy is a prominent feature of the vertebrate auditory system and forms the basis for sound discrimination, but the molecular mechanism that underlies its formation remains largely elusive. Ephrin/Eph signaling is known to play important roles in axon guidance during topographic mapping in other sensory systems, so we investigated its possible role in the establishment of tonotopy in the mouse cochlear nucleus. We found that ephrin-A3 molecules are differentially expressed along the tonotopic axis in the cochlear nucleus during innervation. Ephrin-A3 forward signaling is sufficient to repel auditory nerve fibers in a developmental stage-dependent manner. In mice lacking ephrin-A3, the tonotopic map is degraded and isofrequency bands of neuronal activation upon pure tone exposure become imprecise in the anteroventral cochlear nucleus. Ephrin-A3 mutant mice also exhibit a delayed second wave in auditory brainstem responses upon sound stimuli and impaired detection of sound frequency changes. Our findings establish an essential role for ephrin-A3 in forming precise tonotopy in the auditory brainstem to ensure accurate sound discrimination.
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Affiliation(s)
- Natalia Hoshino
- Department of Biology, Loyola University of Chicago, Chicago, Illinois
| | - Yazan Altarshan
- Department of Biology, Loyola University of Chicago, Chicago, Illinois
| | - Ahmad Alzein
- Department of Biology, Loyola University of Chicago, Chicago, Illinois
| | - Amali M. Fernando
- Department of Biology, Loyola University of Chicago, Chicago, Illinois
| | - Hieu T. Nguyen
- Department of Biology, Loyola University of Chicago, Chicago, Illinois
| | - Emma F. Majewski
- Department of Biology, Loyola University of Chicago, Chicago, Illinois
| | | | | | - Wei-Ming Yu
- Department of Biology, Loyola University of Chicago, Chicago, Illinois
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19
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Chen Z, Huang Y, Yu C, Liu Q, Qiu C, Wan G. Cochlear Sox2 + Glial Cells Are Potent Progenitors for Spiral Ganglion Neuron Reprogramming Induced by Small Molecules. Front Cell Dev Biol 2021; 9:728352. [PMID: 34621745 PMCID: PMC8490772 DOI: 10.3389/fcell.2021.728352] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 08/30/2021] [Indexed: 12/13/2022] Open
Abstract
In the mammalian cochlea, spiral ganglion neurons (SGNs) relay the acoustic information to the central auditory circuits. Degeneration of SGNs is a major cause of sensorineural hearing loss and severely affects the effectiveness of cochlear implant therapy. Cochlear glial cells are able to form spheres and differentiate into neurons in vitro. However, the identity of these progenitor cells is elusive, and it is unclear how to differentiate these cells toward functional SGNs. In this study, we found that Sox2+ subpopulation of cochlear glial cells preserves high potency of neuronal differentiation. Interestingly, Sox2 expression was downregulated during neuronal differentiation and Sox2 overexpression paradoxically inhibited neuronal differentiation. Our data suggest that Sox2+ glial cells are potent SGN progenitor cells, a phenotype independent of Sox2 expression. Furthermore, we identified a combination of small molecules that not only promoted neuronal differentiation of Sox2– glial cells, but also removed glial cell identity and promoted the maturation of the induced neurons (iNs) toward SGN fate. In summary, we identified Sox2+ glial subpopulation with high neuronal potency and small molecules inducing neuronal differentiation toward SGNs.
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Affiliation(s)
- Zhen Chen
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China
| | - Yuhang Huang
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China
| | - Chaorong Yu
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China
| | - Qing Liu
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China
| | - Cui Qiu
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China
| | - Guoqiang Wan
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing, China.,Research Institute of Otolaryngology, Nanjing, China.,Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China.,Institute for Brain Sciences, Nanjing University, Nanjing, China
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20
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Interaction of micropatterned topographical and biochemical cues to direct neurite growth from spiral ganglion neurons. Hear Res 2021; 409:108315. [PMID: 34343850 DOI: 10.1016/j.heares.2021.108315] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 05/07/2021] [Accepted: 07/12/2021] [Indexed: 01/01/2023]
Abstract
Functional outcomes with neural prosthetic devices, such as cochlear implants, are limited in part due to physical separation between the stimulating elements and the neurons they stimulate. One strategy to close this gap aims to precisely guide neurite regeneration to position the neurites in closer proximity to electrode arrays. Here, we explore the ability of micropatterned biochemical and topographic guidance cues, singly and in combination, to direct the growth of spiral ganglion neuron (SGN) neurites, the neurons targeted by cochlear implants. Photopolymerization of methacrylate monomers was used to form unidirectional topographical features of ridges and grooves in addition to multidirectional patterns with 90o angle turns. Microcontact printing was also used to create similar uni- and multi-directional patterns of peptides on polymer surfaces. Biochemical cues included peptides that facilitate (laminin, LN) or repel (EphA4-Fc) neurite growth. On flat surfaces, SGN neurites preferentially grew on LN-coated stripes and avoided EphA4-Fc-coated stripes. LN or EphA4-Fc was selectively adsorbed onto the ridges or grooves to test the neurite response to a combination of topographical and biochemical cues. Coating the ridges with EphA4-Fc and grooves with LN lead to enhanced SGN alignment to topographical patterns. Conversely, EphA4-Fc coating on the grooves or LN coating on the ridges tended to disrupt alignment to topographical patterns. SGN neurites respond to combinations of topographical and biochemical cues and surface patterning that leverages both cues enhance guided neurite growth.
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21
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X-linked Malformation Deafness: Neurodevelopmental Symptoms Are Common in Children With IP3 Malformation and Mutation in POU3F4. Ear Hear 2021; 43:53-69. [PMID: 34133399 PMCID: PMC8694264 DOI: 10.1097/aud.0000000000001073] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Supplemental Digital Content is available in the text. Incomplete partition type 3 (IP3) malformation deafness is a rare hereditary cause of congenital or rapid progressive hearing loss. The children present with a severe to profound mixed hearing loss and temporal bone imaging show a typical inner ear malformation classified as IP3. Cochlear implantation is one option of hearing restoration in severe cases. Little is known about other specific difficulties these children might exhibit, for instance possible neurodevelopmental symptoms.
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22
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Balendran V, Skidmore JM, Ritter KE, Gao J, Cimerman J, Beyer LA, Hurd EA, Raphael Y, Martin DM. Chromatin remodeler CHD7 is critical for cochlear morphogenesis and neurosensory patterning. Dev Biol 2021; 477:11-21. [PMID: 34004180 DOI: 10.1016/j.ydbio.2021.05.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 04/12/2021] [Accepted: 05/10/2021] [Indexed: 11/18/2022]
Abstract
Epigenetic regulation of gene transcription by chromatin remodeling proteins has recently emerged as an important contributing factor in inner ear development. Pathogenic variants in CHD7, the gene encoding Chromodomain Helicase DNA binding protein 7, cause CHARGE syndrome, which presents with malformations in the developing ear. Chd7 is broadly expressed in the developing mouse otocyst and mature auditory epithelium, yet the pathogenic effects of Chd7 loss in the cochlea are not well understood. Here we characterized cochlear epithelial phenotypes in mice with deletion of Chd7 throughout the otocyst (using Foxg1Cre/+ and Pax2Cre), in the otic mesenchyme (using TCre), in hair cells (using Atoh1Cre), in developing neuroblasts (using NgnCre), or in spiral ganglion neurons (using ShhCre/+). Pan-otic deletion of Chd7 resulted in shortened cochleae with aberrant projections and axonal looping, disorganized, supernumerary hair cells at the apical turn and a narrowed epithelium with missing hair cells in the middle region. Deletion of Chd7 in the otic mesenchyme had no effect on overall cochlear morphology. Loss of Chd7 in hair cells did not disrupt their formation or organization of the auditory epithelium. Similarly, absence of Chd7 in spiral ganglion neurons had no effect on axonal projections. In contrast, deletion of Chd7 in developing neuroblasts led to smaller spiral ganglia and disorganized cochlear neurites. Together, these observations reveal dosage-, tissue-, and time-sensitive cell autonomous roles for Chd7 in cochlear elongation and cochlear neuron organization, with minimal functions for Chd7 in hair cells. These studies provide novel information about roles for Chd7 in development of auditory neurons.
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Affiliation(s)
- Vinodh Balendran
- Departments of Pediatrics, The University of Michigan, Ann Arbor, MI, USA
| | | | - K Elaine Ritter
- Departments of Pediatrics, The University of Michigan, Ann Arbor, MI, USA
| | - Jingxia Gao
- Departments of Pediatrics, The University of Michigan, Ann Arbor, MI, USA
| | - Jelka Cimerman
- Departments of Pediatrics, The University of Michigan, Ann Arbor, MI, USA
| | - Lisa A Beyer
- Otolaryngology - Head and Neck Surgery, The University of Michigan, Ann Arbor, MI, USA
| | | | - Yehoash Raphael
- Otolaryngology - Head and Neck Surgery, The University of Michigan, Ann Arbor, MI, USA
| | - Donna M Martin
- Departments of Pediatrics, The University of Michigan, Ann Arbor, MI, USA; Otolaryngology - Head and Neck Surgery, The University of Michigan, Ann Arbor, MI, USA; Human Genetics, The University of Michigan, Ann Arbor, MI, USA.
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23
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Sitko AA, Goodrich LV. Making sense of neural development by comparing wiring strategies for seeing and hearing. Science 2021; 371:eaaz6317. [PMID: 33414193 PMCID: PMC8034811 DOI: 10.1126/science.aaz6317] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The ability to perceive and interact with the world depends on a diverse array of neural circuits specialized for carrying out specific computations. Each circuit is assembled using a relatively limited number of molecules and common developmental steps, from cell fate specification to activity-dependent synaptic refinement. Given this shared toolkit, how do individual circuits acquire their characteristic properties? We explore this question by comparing development of the circuitry for seeing and hearing, highlighting a few examples where differences in each system's sensory demands necessitate different developmental strategies.
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Affiliation(s)
- A A Sitko
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - L V Goodrich
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.
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24
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Webber JL, Clancy JC, Zhou Y, Yraola N, Homma K, García-Añoveros J. Axodendritic versus axosomatic cochlear efferent termination is determined by afferent type in a hierarchical logic of circuit formation. SCIENCE ADVANCES 2021; 7:7/4/eabd8637. [PMID: 33523928 PMCID: PMC7817091 DOI: 10.1126/sciadv.abd8637] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 12/03/2020] [Indexed: 05/09/2023]
Abstract
Hearing involves a stereotyped neural network communicating cochlea and brain. How this sensorineural circuit assembles is largely unknown. The cochlea houses two types of mechanosensory hair cells differing in function (sound transmission versus amplification) and location (inner versus outer compartments). Inner (IHCs) and outer hair cells (OHCs) are each innervated by a distinct pair of afferent and efferent neurons: IHCs are contacted by type I afferents receiving axodendritic efferent contacts; OHCs are contacted by type II afferents and axosomatically terminating efferents. Using an Insm1 mouse mutant with IHCs in the position of OHCs, we discover a hierarchical sequence of instructions in which first IHCs attract, and OHCs repel, type I afferents; second, type II afferents innervate hair cells not contacted by type I afferents; and last, afferent fiber type determines if and how efferents innervate, whether axodendritically on the afferent, axosomatically on the hair cell, or not at all.
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Affiliation(s)
- Jemma L Webber
- Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - John C Clancy
- Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Yingjie Zhou
- Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Natalia Yraola
- Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Kazuaki Homma
- Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and its Disorders, Northwestern University, Chicago, IL 60611, USA
| | - Jaime García-Añoveros
- Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and its Disorders, Northwestern University, Chicago, IL 60611, USA
- Departments of Neurology and Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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25
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van der Valk WH, Steinhart MR, Zhang J, Koehler KR. Building inner ears: recent advances and future challenges for in vitro organoid systems. Cell Death Differ 2020; 28:24-34. [PMID: 33318601 PMCID: PMC7853146 DOI: 10.1038/s41418-020-00678-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 11/04/2020] [Accepted: 11/05/2020] [Indexed: 02/07/2023] Open
Abstract
While inner ear disorders are common, our ability to intervene and recover their sensory function is limited. In vitro models of the inner ear, like the organoid system, could aid in identifying new regenerative drugs and gene therapies. Here, we provide a perspective on the status of in vitro inner ear models and guidance on how to improve their applicability in translational research. We highlight the generation of inner ear cell types from pluripotent stem cells as a particularly promising focus of research. Several exciting recent studies have shown how the developmental signaling cues of embryonic and fetal development can be mimicked to differentiate stem cells into “inner ear organoids” containing otic progenitor cells, hair cells, and neurons. However, current differentiation protocols and our knowledge of embryonic and fetal inner ear development in general, have a bias toward the sensory epithelia of the inner ear. We propose that a more holistic view is needed to better model the inner ear in vitro. Moving forward, attention should be made to the broader diversity of neuroglial and mesenchymal cell types of the inner ear, and how they interact in space or time during development. With improved control of epithelial, neuroglial, and mesenchymal cell fate specification, inner ear organoids would have the ability to truly recapitulate neurosensory function and dysfunction. We conclude by discussing how single-cell atlases of the developing inner ear and technical innovations will be critical tools to advance inner ear organoid platforms for future pre-clinical applications.
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Affiliation(s)
- Wouter H van der Valk
- Department of Otorhinolaryngology and Head & Neck Surgery, Leiden University Medical Center, Leiden, Netherlands.,Department of Otolaryngology, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Matthew R Steinhart
- Department of Otolaryngology, Boston Children's Hospital, Boston, MA, 02115, USA.,Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.,Medical Neuroscience Graduate Program, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Jingyuan Zhang
- Department of Otolaryngology, Boston Children's Hospital, Boston, MA, 02115, USA.,Department of Plastic and Oral Surgery, Boston Children's Hospital, Boston, MA, 02115, USA.,F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, 02115, USA.,Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA, 02115, USA
| | - Karl R Koehler
- Department of Otolaryngology, Boston Children's Hospital, Boston, MA, 02115, USA. .,Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA. .,Department of Plastic and Oral Surgery, Boston Children's Hospital, Boston, MA, 02115, USA. .,F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, 02115, USA. .,Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA, 02115, USA.
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26
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Neuronal processes and glial precursors form a scaffold for wiring the developing mouse cochlea. Nat Commun 2020; 11:5866. [PMID: 33203842 PMCID: PMC7672226 DOI: 10.1038/s41467-020-19521-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 10/02/2020] [Indexed: 01/20/2023] Open
Abstract
In the developing nervous system, axons navigate through complex terrains that change depending on when and where outgrowth begins. For instance, in the developing cochlea, spiral ganglion neurons extend their peripheral processes through a growing and heterogeneous environment en route to their final targets, the hair cells. Although the basic principles of axon guidance are well established, it remains unclear how axons adjust strategies over time and space. Here, we show that neurons with different positions in the spiral ganglion employ different guidance mechanisms, with evidence for both glia-guided growth and fasciculation along a neuronal scaffold. Processes from neurons in the rear of the ganglion are more directed and grow faster than those from neurons at the border of the ganglion. Further, processes at the wavefront grow more efficiently when in contact with glial precursors growing ahead of them. These findings suggest a tiered mechanism for reliable axon guidance.
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27
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Ankamreddy H, Bok J, Groves AK. Uncovering the secreted signals and transcription factors regulating the development of mammalian middle ear ossicles. Dev Dyn 2020; 249:1410-1424. [PMID: 33058336 DOI: 10.1002/dvdy.260] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 10/11/2020] [Accepted: 10/11/2020] [Indexed: 12/22/2022] Open
Abstract
The mammalian middle ear comprises a chain of ossicles, the malleus, incus, and stapes that act as an impedance matching device during the transmission of sound from the tympanic membrane to the inner ear. These ossicles are derived from cranial neural crest cells that undergo endochondral ossification and subsequently differentiate into their final functional forms. Defects that occur during middle ear development can result in conductive hearing loss. In this review, we summarize studies describing the crucial roles played by signaling molecules such as sonic hedgehog, bone morphogenetic proteins, fibroblast growth factors, notch ligands, and chemokines during the differentiation of neural crest into the middle ear ossicles. In addition to these cell-extrinsic signals, we also discuss studies on the function of transcription factor genes such as Foxi3, Tbx1, Bapx1, Pou3f4, and Gsc in regulating the development and morphology of the middle ear ossicles.
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Affiliation(s)
| | - Jinwoong Bok
- Department of Anatomy, Yonsei University College of Medicine, Seoul, South Korea.,Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, South Korea
| | - Andrew K Groves
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
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28
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Cochlear Implantation in a Patient with a Novel POU3F4 Mutation and Incomplete Partition Type-III Malformation. Neural Plast 2020; 2020:8829587. [PMID: 32952548 PMCID: PMC7481964 DOI: 10.1155/2020/8829587] [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: 04/17/2020] [Revised: 08/05/2020] [Accepted: 08/24/2020] [Indexed: 01/01/2023] Open
Abstract
Aims This study is aimed at (1) analyzing the clinical manifestations and genetic features of a novel POU3F4 mutation in a nonsyndromic X-linked recessive hearing loss family and (2) reporting the outcomes of cochlear implantation in a patient with this mutation. Methods A patient who was diagnosed as the IP-III malformation underwent cochlear implantation in our hospital. The genetic analysis was conducted in his family, including the whole-exome sequencing combined with Sanger sequencing and bioinformatic analysis. Clinical features, preoperative auditory and speech performances, and postoperative outcomes of cochlear implant (CI) were assessed on the proband and his family. Results A novel variant c.400_401insACTC (p.Q136LfsX58) in the POU3F4 gene was detected in the family, which was cosegregated with the hearing loss. This variant was absent in 200 normal-hearing persons. The phylogenetic analysis and structure modeling of Pou3f4 protein further confirmed that the novel mutation was pathogenic. The proband underwent cochlear implantation on the right ear at four years old and gained greatly auditory and speech improvement. However, the benefits of the CI declined about three and a half years postoperation. Though the right ear had been reimplanted, the outcomes were still worse than before. Conclusion A novel frame shift variant c.400_401insACTC (p.Q136LfsX58) in the POU3F4 gene was identified in a Chinese family with X-linked inheritance hearing loss. A patient with this mutation and IP-III malformation could get good benefits from CI. However, the outcomes of the cochlear implantation might decline as the patient grows old.
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29
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Scheffel JL, Mohammed SS, Borcean CK, Parng AJ, Yoon HJ, Gutierrez DA, Yu WM. Spatiotemporal Analysis of Cochlear Nucleus Innervation by Spiral Ganglion Neurons that Serve Distinct Regions of the Cochlea. Neuroscience 2020; 446:43-58. [PMID: 32866604 DOI: 10.1016/j.neuroscience.2020.08.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 08/21/2020] [Accepted: 08/21/2020] [Indexed: 10/23/2022]
Abstract
Cochlear neurons innervate the brainstem cochlear nucleus in a tonotopic fashion according to their sensitivity to different sound frequencies (known as the neuron's characteristic frequency). It is unclear whether these neurons with distinct characteristic frequencies use different strategies to innervate the cochlear nucleus. Here, we use genetic approaches to differentially label spiral ganglion neurons (SGNs) and their auditory nerve fibers (ANFs) that relay different characteristic frequencies in mice. We found that SGN populations that supply distinct regions of the cochlea employ different cellular strategies to target and innervate neurons in the cochlear nucleus during tonotopic map formation. ANFs that will exhibit high-characteristic frequencies initially overshoot and sample a large area of targets before refining their connections to correct targets, while fibers that will exhibit low-characteristic frequencies are more accurate in initial targeting and undergo minimal target sampling. Moreover, similar to their peripheral projections, the central projections of ANFs show a gradient of development along the tonotopic axis, with outgrowth and branching of prospective high-frequency ANFs initiated about two days earlier than those of prospective low-frequency ANFs. The processes of synaptogenesis are similar between high- and low-frequency ANFs, but a higher proportion of low-frequency ANFs form smaller endbulb synaptic endings. These observations reveal the diversity of cellular mechanisms that auditory neurons that will become functionally distinct use to innervate their targets during tonotopic map formation.
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Affiliation(s)
- Jennifer L Scheffel
- Department of Biology, Loyola University Chicago, Chicago, IL 60660, United States
| | - Samiha S Mohammed
- Department of Biology, Loyola University Chicago, Chicago, IL 60660, United States
| | - Chloe K Borcean
- Department of Biology, Loyola University Chicago, Chicago, IL 60660, United States
| | - Annie J Parng
- Department of Biology, Loyola University Chicago, Chicago, IL 60660, United States
| | - Hyun Ju Yoon
- Department of Biology, Loyola University Chicago, Chicago, IL 60660, United States
| | - Darwin A Gutierrez
- Department of Biology, Loyola University Chicago, Chicago, IL 60660, United States
| | - Wei-Ming Yu
- Department of Biology, Loyola University Chicago, Chicago, IL 60660, United States.
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30
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Huang J, Zuo N, Wu C, Chen P, Ma J, Wang C, Li W, Liu S. Role of the periotic mesenchyme in the development of sensory cells in early mouse cochlea. J Otol 2020; 15:138-143. [PMID: 33293914 PMCID: PMC7691837 DOI: 10.1016/j.joto.2020.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 05/28/2020] [Accepted: 06/01/2020] [Indexed: 11/28/2022] Open
Abstract
Objective To investigate the role of the periotic mesenchyme (POM) in the development of sensory cells of developing auditory epithelium. Methods Developing auditory epithelium with or without periotic mesenchyme was isolated from mice at embryonic days 11.5 (E11.5), E12.5 and E13.5, respectively, and cultured in vitro to an equivalent of E18.5’s epithelium in vivo. Then, the explants were co-stained with antibodies targeting myosin VIIA, Sox2 and BrdU. Results More hair cells in E11.5 + 7 DIV, E12.5 + 6 DIV and E13.5 + 5 DIV auditory epithelia were found upon culture with POM (225.90 ± 62.44, 476.94 ± 100.81, and 1386.60 ± 202.38, respectively) compared with the non-POM group (68.17 ± 23.74, 205.00 ± 44.23, and 1266.80 ± 38.84, respectively). Moreover, regardless of developmental stage, the mesenchymal tissue increased the amount of cochlear sensory cells as well as the ratio of differentiated hair cells to total sensory cells. Conclusions The periotic mesenchyme promotes the development of cochlear sensory cells, and its effect depends on the developmental stage of the auditory epithelium.
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Affiliation(s)
- Jingjiang Huang
- Department of Otolaryngology-Head and Neck Surgery, Yijishan Hospital of Wannan Medical College, Wuhu, Anhui, 241001, China
| | - Na Zuo
- Department of Otolaryngology-Head and Neck Surgery, Yijishan Hospital of Wannan Medical College, Wuhu, Anhui, 241001, China
| | - Cheng Wu
- Department of Otolaryngology-Head and Neck Surgery, Yijishan Hospital of Wannan Medical College, Wuhu, Anhui, 241001, China
| | - Peipei Chen
- Department of Otolaryngology-Head and Neck Surgery, Yijishan Hospital of Wannan Medical College, Wuhu, Anhui, 241001, China
| | - Jun Ma
- Department of Otolaryngology-Head and Neck Surgery, Yijishan Hospital of Wannan Medical College, Wuhu, Anhui, 241001, China
| | - Chuanxi Wang
- Department of Otolaryngology-Head and Neck Surgery, Yijishan Hospital of Wannan Medical College, Wuhu, Anhui, 241001, China
| | - Wenyan Li
- ENT Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China.,Key Laboratory of Hearing Medicine of NHFPC, Shanghai, 200031, China
| | - Shaofeng Liu
- Department of Otolaryngology-Head and Neck Surgery, Yijishan Hospital of Wannan Medical College, Wuhu, Anhui, 241001, China
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31
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Smith JD, El-Kashlan N, Darr OAF, Thorne MC. Systematic Review of Outcomes After Cochlear Implantation in Children With X-Linked Deafness-2. Otolaryngol Head Neck Surg 2020; 164:19-26. [PMID: 32600118 DOI: 10.1177/0194599820932138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Outcomes following cochlear implantation in children with X-linked deafness-2 are variable, resulting in challenges in appropriate preoperative counseling. To address this uncertainty, we performed a systematic review and synthesis of the literature on audiologic and speech outcomes after cochlear implantation in these patients to inform prognostic counseling. DATA SOURCES PubMed, Embase, and Cochrane Library were queried for articles published between January 2000 and July 2019. REVIEW METHODS We performed a systematic review of all studies published between 2000 and 2019 that reported on (1) children with confirmed X-linked deafness-2 undergoing cochlear implantation and (2) formal assessment of hearing and/or speech capabilities postimplantation. RESULTS Our initial database search yielded 313 articles. Fourteen articles met inclusion criteria. These studies reported on 61 children with X-linked deafness-2 who underwent implantation at a wide age range (1-29 years) for severe-profound sensorineural hearing loss of prelingual onset. The mean follow-up duration after implant activation was 32 months (range, 12-61). Outcome domains assessed at follow-up were heterogeneous, though each study employed at least 1 assessment of hearing (eg, pure tone audiometry), speech perception (eg, Early Speech Perception Test), or auditory perception (eg, Categories of Auditory Perception scores). In 10 of 14 studies, cochlear implantation afforded significant improvement in hearing and speech capabilities relative to preoperative performance or as compared with age-matched, normal-hearing controls. CONCLUSION The majority of studies demonstrate that cochlear implantation provides improvements in hearing and speech performance in patients with X-linked deafness-2. This information is valuable for decision making regarding cochlear implantation in these patients.
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Affiliation(s)
- Joshua D Smith
- Department of Otolaryngology-Head and Neck Surgery, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Nour El-Kashlan
- Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Owen A F Darr
- Department of Pediatric Otolaryngology, Children's Hospital Colorado, Aurora, Colorado, USA
| | - Marc C Thorne
- Department of Otolaryngology-Head and Neck Surgery, University of Michigan Medical School, Ann Arbor, Michigan, USA
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32
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D'Arco F, Sanverdi E, O'Brien WT, Taranath A, Talenti G, Blaser SI. The link between inner ear malformations and the rest of the body: what we know so far about genetic, imaging and histology. Neuroradiology 2020; 62:539-544. [PMID: 32125475 DOI: 10.1007/s00234-020-02382-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 02/17/2020] [Indexed: 11/29/2022]
Affiliation(s)
- Felice D'Arco
- Department of Radiology, Great Ormond Street Hospital for Children, London, UK.
| | - Eser Sanverdi
- Department of Radiology, Great Ormond Street Hospital for Children, London, UK
| | - William T O'Brien
- Department of Radiology and Medical Imaging, Cincinnati Children's Hospital Medical Center, Cincinnati, USA
| | - Ajay Taranath
- Department of Radiology, Women's and Children's Hospital, North Adelaide, South Australia, Australia
| | - Giacomo Talenti
- Department of Diagnostics and Pathology, Neuroradiology Unit, Verona University Hospital, Verona, Italy
| | - Susan I Blaser
- Division of Neuroradiology, Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada
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33
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Brooks PM, Rose KP, MacRae ML, Rangoussis KM, Gurjar M, Hertzano R, Coate TM. Pou3f4-expressing otic mesenchyme cells promote spiral ganglion neuron survival in the postnatal mouse cochlea. J Comp Neurol 2020; 528:1967-1985. [PMID: 31994726 DOI: 10.1002/cne.24867] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 01/13/2020] [Accepted: 01/16/2020] [Indexed: 12/20/2022]
Abstract
During inner ear development, primary auditory neurons named spiral ganglion neurons (SGNs) are surrounded by otic mesenchyme cells, which express the transcription factor Pou3f4. Mutations in Pou3f4 are associated with DFNX2, the most common form of X-linked deafness and typically include developmental malformations of the middle ear and inner ear. It is known that interactions between Pou3f4-expressing mesenchyme cells and SGNs are important for proper axon bundling during development. However, Pou3f4 continues to be expressed through later phases of development, and potential interactions between Pou3f4 and SGNs during this period had not been explored. To address this, we documented Pou3f4 protein expression in the early postnatal mouse cochlea and compared SGNs in Pou3f4 knockout mice and littermate controls. In Pou3f4y/- mice, SGN density begins to decline by the end of the first postnatal week, with approximately 25% of SGNs ultimately lost. This period of SGN loss in Pou3f4y/- cochleae coincides with significant elevations in SGN apoptosis. Interestingly, this period also coincides with the presence of a transient population of Pou3f4-expressing cells around and within the spiral ganglion. To determine if Pou3f4 is normally required for SGN peripheral axon extension into the sensory domain, we used a genetic sparse labeling approach to track SGNs and found no differences compared with controls. We also found that Pou3f4 loss did not lead to changes in the proportions of Type I SGN subtypes. Overall, these data suggest that otic mesenchyme cells may play a role in maintaining SGN populations during the early postnatal period.
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Affiliation(s)
- Paige M Brooks
- Department of Biology, Georgetown University, Washington, District of Columbia
| | - Kevin P Rose
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, University of Maryland, Baltimore, Maryland
| | - Meaghan L MacRae
- Department of Biology, Georgetown University, Washington, District of Columbia
| | | | - Mansa Gurjar
- Department of Biology, Georgetown University, Washington, District of Columbia
| | - Ronna Hertzano
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, University of Maryland, Baltimore, Maryland.,Department of Anatomy and Neurobiology, University of Maryland School of Medicine, University of Maryland, Baltimore, Maryland.,Institute for Genome Sciences, University of Maryland School of Medicine, University of Maryland, Baltimore, Maryland
| | - Thomas M Coate
- Department of Biology, Georgetown University, Washington, District of Columbia
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Ocak E, Duman D, Tekin M. Genetic Causes of Inner Ear Anomalies: a Review from the Turkish Study Group for Inner Ear Anomalies. Balkan Med J 2019; 36:206-211. [PMID: 31131597 PMCID: PMC6636654 DOI: 10.4274/balkanmedj.galenos.2019.2019.4.66] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Inner ear anomalies diagnosed using a radiological study are detected in almost 30% of cases with congenital or prelingual-onset sensorineural hearing loss. Inner ear anomalies can be isolated or occur along with a part of a syndrome involving other systems. Although astonishing progress has been made in research aimed at revealing the genetic causes of hearing loss in the past few decades, only a few genes have been linked to inner ear anomalies. The aim of this review is to discuss the known genetic causes of inner ear anomalies. Identifying the genetic causes of inner ear anomalies is important for guiding clinical care that includes empowered reproductive decisions provided to the affected individuals. Furthermore, understanding the molecular underpinnings of the development of the inner ear in humans is important to develop novel treatment strategies for people with hearing loss.
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Affiliation(s)
- Emre Ocak
- Department of Otolaryngology, Ankara University School of Medicine, Ankara, Turkey
| | - Duygu Duman
- Division of Genetics, Department of Pediatrics, Ankara University School of Medicine, Ankara, Turkey,Department of Audiology, Ankara University Faculty of Health Sciences, Ankara, Turkey
| | - Mustafa Tekin
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, USA,Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, USA,Dr. John T. Macdonald Department of Human Genetics, University of Miami Miller School of Medicine, Miami, USA
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Defourny J. Eph/ephrin signalling in the development and function of the mammalian cochlea. Dev Biol 2019; 449:35-40. [PMID: 30771305 DOI: 10.1016/j.ydbio.2019.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 02/10/2019] [Accepted: 02/11/2019] [Indexed: 12/12/2022]
Abstract
In mammals, the functional development of the cochlea requires the tight regulation of multiple molecules and signalling pathways including fibroblast growth factors, bone morphogenetic proteins, Wnt and Notch signalling pathways. Over the last decade, the Eph/ephrin system also emerged as a key player of the development and function of the mammalian cochlea. In this review, we discuss the recent advances on the role of Eph/ephrin signalling in patterning the cochlear sensory epithelium and the complex innervation of mechanosensory hair cells by spiral ganglion neurons. Finally, we address the issue of a syndromic form of hearing loss caused by a deficient member of the Eph/ephrin family.
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Affiliation(s)
- Jean Defourny
- GIGA-Neurosciences, Unit of Cell and Tissue Biology, University of Liège, C.H.U. B36, B-4000, Liège, Belgium.
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Sharma K, Seo YW, Yi E. Differential Expression of Ca 2+-buffering Protein Calretinin in Cochlear Afferent Fibers: A Possible Link to Vulnerability to Traumatic Noise. Exp Neurobiol 2018; 27:397-407. [PMID: 30429649 PMCID: PMC6221833 DOI: 10.5607/en.2018.27.5.397] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 09/28/2018] [Accepted: 10/02/2018] [Indexed: 12/18/2022] Open
Abstract
The synaptic contacts of cochlear afferent fibers (CAFs) with inner hair cells (IHCs) are spatially segregated according to their firing properties. CAFs also exhibit spatially segregated vulnerabilities to noise. The CAF fibers contacting the modiolar side of IHCs tend to be more vulnerable. Noise vulnerability is thought to be due to the absence of neuroprotective mechanisms in the modiolar side contacting CAFs. In this study, we investigated whether the expression of neuroprotective Ca2+-buffering proteins is spatially segregated in CAFs. The expression patterns of calretinin, parvalbumin, and calbindin were examined in rat CAFs using immunolabeling. Calretinin-rich fibers, which made up ~50% of the neurofilament (NF)-positive fibers, took the pillar side course and contacted all IHC sides. NF-positive and calretinin-poor fibers took the modiolar side pathway and contacted the modiolar side of IHCs. Both fiber categories juxtaposed the C-terminal binding protein 2 (CtBP2) puncta and were contacted by synaptophysin puncta. These results indicated that the calretinin-poor fibers, like the calretinin-rich ones, were afferent fibers and probably formed functional efferent synapses. However, the other Ca2+-buffering proteins did not exhibit CAF subgroup specificity. Most CAFs near IHCs were parvalbumin-positive. Only the pillar-side half of parvalbumin-positive fibers coexpressed calretinin. Calbindin was not detected in any nerve fibers near IHCs. Taken together, of the Ca2+-buffering proteins examined, only calretinin exhibited spatial segregation at IHC-CAF synapses. The absence of calretinin in modiolar-side CAFs might be related to the noise vulnerability of the fibers.
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Affiliation(s)
- Kushal Sharma
- College of Pharmacy and Natural Medicine Research Institute, Mokpo National University, Muan 58554, Korea
| | - Young-Woo Seo
- Korea Basic Science Institute Gwangju Center, Gwangju 61186, Korea
| | - Eunyoung Yi
- College of Pharmacy and Natural Medicine Research Institute, Mokpo National University, Muan 58554, Korea
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Harley RJ, Murdy JP, Wang Z, Kelly MC, Ropp TJF, Park SH, Maness PF, Manis PB, Coate TM. Neuronal cell adhesion molecule (NrCAM) is expressed by sensory cells in the cochlea and is necessary for proper cochlear innervation and sensory domain patterning during development. Dev Dyn 2018; 247:934-950. [PMID: 29536590 PMCID: PMC6105381 DOI: 10.1002/dvdy.24629] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 03/06/2018] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND In the cochlea, auditory development depends on precise patterns of innervation by afferent and efferent nerve fibers, as well as a stereotyped arrangement of hair and supporting cells. Neuronal cell adhesion molecule (NrCAM) is a homophilic cell adhesion molecule that controls diverse aspects of nervous system development, but the function of NrCAM in cochlear development is not well understood. RESULTS Throughout cochlear innervation, NrCAM is detectable on spiral ganglion neuron (SGN) afferent and olivocochlear efferent fibers, and on the membranes of developing hair and supporting cells. Neonatal Nrcam-null cochleae show errors in type II SGN fasciculation, reduced efferent innervation, and defects in the stereotyped packing of hair and supporting cells. Nrcam loss also leads to dramatic changes in the profiles of presynaptic afferent and efferent synaptic markers at the time of hearing onset. Despite these numerous developmental defects, Nrcam-null adults do not show defects in auditory acuity, and by postnatal day 21, the developmental deficits in ribbon synapse distribution and sensory domain structure appear to have been corrected. CONCLUSIONS NrCAM is expressed by several neural and sensory epithelial subtypes within the developing cochlea, and the loss of Nrcam confers numerous, but nonpermanent, developmental defects in innervation and sensory domain patterning. Developmental Dynamics 247:934-950, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Randall J. Harley
- Department of Biology, Georgetown University, 37 and O St. NW, Regents Hall 410, Washington, DC 20007, USA
| | - Joseph P. Murdy
- Department of Biology, Georgetown University, 37 and O St. NW, Regents Hall 410, Washington, DC 20007, USA
| | - Zhirong Wang
- Department of Biology, Georgetown University, 37 and O St. NW, Regents Hall 410, Washington, DC 20007, USA
| | - Michael C. Kelly
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, 35 Convent Dr., Bethesda, MD 20892, USA
| | - Tessa-Jonne F. Ropp
- Department of Otolaryngology/Head and Neck Surgery, The University of North Carolina at Chapel Hill, B251 Marsico Hall, CB#7070, 125 Mason Farm Rd., Chapel Hill, NC 27599, USA
| | - SeHoon H. Park
- Department of Biology, Georgetown University, 37 and O St. NW, Regents Hall 410, Washington, DC 20007, USA
| | - Patricia F. Maness
- Department of Biochemistry and Biophysics, The University of North Carolina School of Medicine, 120 Mason Farm Rd., suite 3020, CB#7260, Chapel Hill, NC 27599, USA
| | - Paul B. Manis
- Department of Otolaryngology/Head and Neck Surgery and Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, B027 Marsico Hall, CB#7070. 125 Mason Farm Rd., Chapel Hill, NC 27599
| | - Thomas M. Coate
- Department of Biology, Georgetown University, 37 and O St. NW, Regents Hall 410, Washington, DC 20007, USA
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Tuft BW, Xu L, Leigh B, Lee D, Guymon CA, Hansen MR. Photopolymerized micropatterns with high feature frequencies overcome chemorepulsive borders to direct neurite growth. J Tissue Eng Regen Med 2017; 12:e1392-e1403. [PMID: 28753740 DOI: 10.1002/term.2527] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 07/03/2017] [Accepted: 07/24/2017] [Indexed: 01/04/2023]
Abstract
Developing and regenerating neurites respond to a variety of biophysical and biochemical cues in their micro-environment to reach target cells and establish appropriate synapses. Defining the hierarchal relationship of both types of cues to direct neurite growth carries broad significance for neural development, regeneration, and, in particular, engineering of neural prostheses that improve tissue integration with native neural networks. In this work, chemorepulsive biochemical borders are established on substrates with a range of surface microfeatures to determine the potential of physical cues to overcome conflicting biochemical cues. Physical micropatterns are fabricated using photomasking techniques to spatially control photoinitiation events of the polymerization. Temporal control of the reaction allows for generation of microfeatures with the same amplitude across a range of feature frequencies or periodicities. The micropatterned substrates are then modified with repulsive chemical borders between laminin and either EphA4-Fc or tenascin C that compete with the surface microfeatures to direct neurite growth. Behaviour of neurites from spiral ganglion and trigeminal neurons is characterized at biochemical borders as cross, turn, stop, or repel events. Both the chemical borders and physical patterns significantly influence neurite pathfinding. On unpatterned surfaces, most neurites that originate on laminin are deterred by the border with tenascin C or EphA4-Fc. Importantly, substrates with frequent micropattern features overcome the influence of the chemorepulsive border to dominate neurite trajectory. Designing prosthesis interfaces with appropriate surface features may allow for spatially organized neurite outgrowth in vivo even in the presence of conflicting biochemical cues in native target tissues.
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Affiliation(s)
- Bradley W Tuft
- Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, IA, USA
| | - Linjing Xu
- Department of Otolaryngology - Head and Neck Surgery, University of Iowa, Iowa City, IA, USA
| | - Braden Leigh
- Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, IA, USA
| | - Daniel Lee
- Department of Otolaryngology - Head and Neck Surgery, University of Iowa, Iowa City, IA, USA
| | - C Allan Guymon
- Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, IA, USA
| | - Marlan R Hansen
- Department of Otolaryngology - Head and Neck Surgery, University of Iowa, Iowa City, IA, USA.,Department of Neurosurgery, University of Iowa, Iowa City, IA, USA
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Mao B, Moss CF, Wilkinson GS. Age-dependent gene expression in the inner ear of big brown bats (Eptesicus fuscus). PLoS One 2017; 12:e0186667. [PMID: 29073148 PMCID: PMC5658057 DOI: 10.1371/journal.pone.0186667] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Accepted: 10/05/2017] [Indexed: 12/25/2022] Open
Abstract
For echolocating bats, hearing is essential for survival. Specializations for detecting and processing high frequency sounds are apparent throughout their auditory systems. Recent studies on echolocating mammals have reported evidence of parallel evolution in some hearing-related genes in which distantly related groups of echolocating animals (bats and toothed whales), cluster together in gene trees due to apparent amino acid convergence. However, molecular adaptations can occur not only in coding sequences, but also in the regulation of gene expression. The aim of this study was to examine the expression of hearing-related genes in the inner ear of developing big brown bats, Eptesicus fuscus, during the period in which echolocation vocalizations increase dramatically in frequency. We found that seven genes were significantly upregulated in juveniles relative to adults, and that the expression of four genes through development correlated with estimated age. Compared to available data for mice, it appears that expression of some hearing genes is extended in juvenile bats. These results are consistent with a prolonged growth period required to develop larger cochlea relative to body size, a later maturation of high frequency hearing, and a greater dependence on high frequency hearing in echolocating bats.
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Affiliation(s)
- Beatrice Mao
- Department of Biology, College of Computer, Mathematical, and Natural Sciences, University of Maryland, College Park, Maryland, United States of America
| | - Cynthia F. Moss
- Department of Psychological and Brain Sciences, Zanvyl Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, Maryland, United States of America
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Gerald S. Wilkinson
- Department of Biology, College of Computer, Mathematical, and Natural Sciences, University of Maryland, College Park, Maryland, United States of America
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40
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Xu J, Ueno H, Xu CY, Chen B, Weissman IL, Xu PX. Identification of mouse cochlear progenitors that develop hair and supporting cells in the organ of Corti. Nat Commun 2017; 8:15046. [PMID: 28492243 PMCID: PMC5437288 DOI: 10.1038/ncomms15046] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 02/23/2017] [Indexed: 01/20/2023] Open
Abstract
The adult mammalian cochlear sensory epithelium houses two major types of cells, mechanosensory hair cells and underlying supporting cells, and lacks regenerative capacity. Recent evidence indicates that a subset of supporting cells can spontaneously regenerate hair cells after ablation only within the first week postparturition. Here in vivo clonal analysis of mouse inner ear cells during development demonstrates clonal relationship between hair and supporting cells in sensory organs. We report the identification in mouse of a previously unknown population of multipotent stem/progenitor cells that are capable of not only contributing to the hair and supporting cells but also to other cell types, including glia, in cochlea undergoing development, maturation and repair in response to damage. These multipotent progenitors originate from Eya1-expressing otic progenitors. Our findings also provide evidence for detectable regenerative potential in the postnatal cochlea beyond 1 week of age.
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Affiliation(s)
- Jinshu Xu
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Hiroo Ueno
- Institute of Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, California 94305, USA
- Ludwig Center, Stanford University, Stanford, California 94305, USA
- Department of Pathology, Stanford University, Stanford, California 94305, USA
| | - Chelsea Y. Xu
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Binglai Chen
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Irving L. Weissman
- Institute of Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, California 94305, USA
- Ludwig Center, Stanford University, Stanford, California 94305, USA
- Department of Pathology, Stanford University, Stanford, California 94305, USA
| | - Pin-Xian Xu
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
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Šmít D, Fouquet C, Pincet F, Zapotocky M, Trembleau A. Axon tension regulates fasciculation/defasciculation through the control of axon shaft zippering. eLife 2017; 6:19907. [PMID: 28422009 PMCID: PMC5478281 DOI: 10.7554/elife.19907] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 04/04/2017] [Indexed: 01/16/2023] Open
Abstract
While axon fasciculation plays a key role in the development of neural networks, very little is known about its dynamics and the underlying biophysical mechanisms. In a model system composed of neurons grown ex vivo from explants of embryonic mouse olfactory epithelia, we observed that axons dynamically interact with each other through their shafts, leading to zippering and unzippering behavior that regulates their fasciculation. Taking advantage of this new preparation suitable for studying such interactions, we carried out a detailed biophysical analysis of zippering, occurring either spontaneously or induced by micromanipulations and pharmacological treatments. We show that zippering arises from the competition of axon-axon adhesion and mechanical tension in the axons, and provide the first quantification of the force of axon-axon adhesion. Furthermore, we introduce a biophysical model of the zippering dynamics, and we quantitatively relate the individual zipper properties to global characteristics of the developing axon network. Our study uncovers a new role of mechanical tension in neural development: the regulation of axon fasciculation.
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Affiliation(s)
- Daniel Šmít
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Coralie Fouquet
- Neuroscience Paris Seine - Institute of Biology Paris Seine, Sorbonne Université, UPMC Univ Paris 06, INSERM, CNRS, Paris, France
| | - Frédéric Pincet
- Laboratoire de Physique Statistique, Ecole Normale Superieure, PSL Research University, Paris, France
| | - Martin Zapotocky
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Alain Trembleau
- Neuroscience Paris Seine - Institute of Biology Paris Seine, Sorbonne Université, UPMC Univ Paris 06, INSERM, CNRS, Paris, France
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Pejvakin, a Candidate Stereociliary Rootlet Protein, Regulates Hair Cell Function in a Cell-Autonomous Manner. J Neurosci 2017; 37:3447-3464. [PMID: 28209736 DOI: 10.1523/jneurosci.2711-16.2017] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 01/02/2017] [Accepted: 01/25/2017] [Indexed: 11/21/2022] Open
Abstract
Mutations in the Pejvakin (PJVK) gene are thought to cause auditory neuropathy and hearing loss of cochlear origin by affecting noise-induced peroxisome proliferation in auditory hair cells and neurons. Here we demonstrate that loss of pejvakin in hair cells, but not in neurons, causes profound hearing loss and outer hair cell degeneration in mice. Pejvakin binds to and colocalizes with the rootlet component TRIOBP at the base of stereocilia in injectoporated hair cells, a pattern that is disrupted by deafness-associated PJVK mutations. Hair cells of pejvakin-deficient mice develop normal rootlets, but hair bundle morphology and mechanotransduction are affected before the onset of hearing. Some mechanotransducing shorter row stereocilia are missing, whereas the remaining ones exhibit overextended tips and a greater variability in height and width. Unlike previous studies of Pjvk alleles with neuronal dysfunction, our findings reveal a cell-autonomous role of pejvakin in maintaining stereocilia architecture that is critical for hair cell function.SIGNIFICANCE STATEMENT Two missense mutations in the Pejvakin (PJVK or DFNB59) gene were first identified in patients with audiological hallmarks of auditory neuropathy spectrum disorder, whereas all other PJVK alleles cause hearing loss of cochlear origin. These findings suggest that complex pathogenetic mechanisms underlie human deafness DFNB59. In contrast to recent studies, we demonstrate that pejvakin in auditory neurons is not essential for normal hearing in mice. Moreover, pejvakin localizes to stereociliary rootlets in hair cells and is required for stereocilia maintenance and mechanosensory function of the hair bundle. Delineating the site of the lesion and the mechanisms underlying DFNB59 will allow clinicians to predict the efficacy of different therapeutic approaches, such as determining compatibility for cochlear implants.
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Synchronized Progression of Prestin Expression and Auditory Brainstem Response during Postnatal Development in Rats. Neural Plast 2016; 2016:4545826. [PMID: 28097024 PMCID: PMC5210174 DOI: 10.1155/2016/4545826] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 11/08/2016] [Accepted: 11/30/2016] [Indexed: 12/23/2022] Open
Abstract
Prestin is the motor protein expressed in the cochlear outer hair cells (OHCs) of mammalian inner ear. The electromotility of OHCs driven by prestin is responsible for the cochlear amplification which is required for normal hearing in adult animals. Postnatal expression of prestin and activity of OHCs may contribute to the maturation of hearing in rodents. However, the temporal and spatial expression of prestin in cochlea during the development is not well characterized. In the present study, we examined the expression and function of prestin from the OHCs in apical, middle, and basal turns of the cochleae of postnatal rats. Prestin first appeared at postnatal day 6 (P6) for basal turn, P7 in middle turn, and P9 for apical turn of cochlea. The expression level increased progressively over the next few days and by P14 reached the mature level for all three segments. By comparison with the time course of the development of auditory brainstem response for different frequencies, our data reveal that prestin expression synchronized with the hearing development. The present study suggests that the onset time of hearing may require the expression of prestin and is determined by the mature function of OHCs.
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Zhang KD, Coate TM. Recent advances in the development and function of type II spiral ganglion neurons in the mammalian inner ear. Semin Cell Dev Biol 2016; 65:80-87. [PMID: 27760385 DOI: 10.1016/j.semcdb.2016.09.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 08/12/2016] [Accepted: 09/25/2016] [Indexed: 01/17/2023]
Abstract
In hearing, mechanically sensitive hair cells (HCs) in the cochlea release glutamate onto spiral ganglion neurons (SGNs) to relay auditory information to the central nervous system (CNS). There are two main SGN subtypes, which differ in morphology, number, synaptic targets, innervation patterns and firing properties. About 90-95% of SGNs are the type I SGNs, which make a single bouton connection with inner hair cells (IHCs) and have been well described in the canonical auditory pathway for sound detection. However, less attention has been given to the type II SGNs, which exclusively innervate outer hair cells (OHCs). In this review, we emphasize recent advances in the molecular mechanisms that control how type II SGNs develop and form connections with OHCs, and exciting new insights into the function of type II SGNs.
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Affiliation(s)
- Kaidi D Zhang
- Department of Biology, Georgetown University, Washington, DC, USA.
| | - Thomas M Coate
- Department of Biology, Georgetown University, Washington, DC, USA
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45
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Smith FL, Davis RL. Organ of Corti explants direct tonotopically graded morphology of spiral ganglion neurons in vitro. J Comp Neurol 2016; 524:2182-207. [PMID: 26663318 DOI: 10.1002/cne.23940] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 11/12/2015] [Accepted: 11/30/2015] [Indexed: 01/25/2023]
Abstract
The spiral ganglion is a compelling model system to examine how morphological form contributes to sensory function. While the ganglion is composed mainly of a single class of type I neurons that make simple one-to-one connections with inner hair cell sensory receptors, it has an elaborate overall morphological design. Specific features, such as soma size and axon outgrowth, are graded along the spiral contour of the cochlea. To begin to understand the interplay between different regulators of neuronal morphology, we cocultured neuron explants with peripheral target tissues removed from distinct cochlear locations. Interestingly, these "hair cell microisolates" were capable of both increasing and decreasing neuronal somata size, without adversely affecting survival. Moreover, axon characteristics elaborated de novo by the primary afferents in culture were systematically regulated by the sensory endorgan. Apparent peripheral nervous system (PNS)-like and central nervous system (CNS)-like axonal profiles were established in our cocultures allowing an analysis of putative PNS/CNS axon length ratios. As predicted from the in vivo organization, PNS-like axon bundles elaborated by apical cocultures were longer than their basal counterparts and this phenotype was methodically altered when neuron explants were cocultured with microisolates from disparate cochlear regions. Thus, location-dependent signals within the organ of Corti may set the "address" of neurons within the spiral ganglion, allowing them to elaborate the appropriate tonotopically associated morphological features in order to carry out their signaling function. J. Comp. Neurol. 524:2182-2207, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Felicia L Smith
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, USA
| | - Robin L Davis
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, USA
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ROR1 is essential for proper innervation of auditory hair cells and hearing in humans and mice. Proc Natl Acad Sci U S A 2016; 113:5993-8. [PMID: 27162350 DOI: 10.1073/pnas.1522512113] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Hair cells of the inner ear, the mechanosensory receptors, convert sound waves into neural signals that are passed to the brain via the auditory nerve. Little is known about the molecular mechanisms that govern the development of hair cell-neuronal connections. We ascertained a family with autosomal recessive deafness associated with a common cavity inner ear malformation and auditory neuropathy. Via whole-exome sequencing, we identified a variant (c.2207G>C, p.R736T) in ROR1 (receptor tyrosine kinase-like orphan receptor 1), cosegregating with deafness in the family and absent in ethnicity-matched controls. ROR1 is a tyrosine kinase-like receptor localized at the plasma membrane. At the cellular level, the mutation prevents the protein from reaching the cellular membrane. In the presence of WNT5A, a known ROR1 ligand, the mutated ROR1 fails to activate NF-κB. Ror1 is expressed in the inner ear during development at embryonic and postnatal stages. We demonstrate that Ror1 mutant mice are severely deaf, with preserved otoacoustic emissions. Anatomically, mutant mice display malformed cochleae. Axons of spiral ganglion neurons show fasciculation defects. Type I neurons show impaired synapses with inner hair cells, and type II neurons display aberrant projections through the cochlear sensory epithelium. We conclude that Ror1 is crucial for spiral ganglion neurons to innervate auditory hair cells. Impairment of ROR1 function largely affects development of the inner ear and hearing in humans and mice.
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Abstract
UNLABELLED A hallmark of the nervous system is the presence of precise patterns of connections between different types of neurons. Many mechanisms can be used to establish specificity, including homophilic adhesion and synaptic refinement, but the range of strategies used across the nervous system remains unclear. To broaden the understanding of how neurons find their targets, we studied the developing murine cochlea, where two classes of spiral ganglion neurons (SGNs), type I and type II, navigate together to the sensory epithelium and then diverge to contact inner hair cells (IHCs) or outer hair cells (OHCs), respectively. Neurons with type I and type II morphologies are apparent before birth, suggesting that target selection might be accomplished by excluding type I processes from the OHC region. However, because type I processes appear to overshoot into type II territory postnatally, specificity may also depend on elimination of inappropriate synapses. To resolve these differences, we analyzed the morphology and dynamic behaviors of individual fibers and their branches as they interact with potential partners. We found that SGN processes continue to be segregated anatomically in the postnatal cochlea. Although type I-like fibers branched locally, few branches contacted OHCs, arguing against synaptic elimination. Instead, time-lapse imaging studies suggest a prominent role for retraction, first positioning processes to the appropriate region and then corralling branches during a subsequent period of exuberant growth and refinement. Thus, sequential stages of retraction can help to achieve target specificity, adding to the list of mechanisms available for sculpting neural circuits. SIGNIFICANCE STATEMENT During development, different types of neurons must form connections with specific synaptic targets, thereby creating the precise wiring diagram necessary for adult function. Although studies have revealed multiple mechanisms for target selection, we still know little about how different strategies are used to produce each circuit's unique pattern of connectivity. Here we combined neurite-tracing and time-lapse imaging to define the events that lead to the simple binary wiring specificity of the cochlea. A better understanding of how the cochlea is innervated will broaden our knowledge of target selection across the nervous system, offer new insights into the developmental origins of deafness, and guide efforts to restore connectivity in the damaged cochlea.
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Dcc Mediates Functional Assembly of Peripheral Auditory Circuits. Sci Rep 2016; 6:23799. [PMID: 27040640 PMCID: PMC4819185 DOI: 10.1038/srep23799] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 03/11/2016] [Indexed: 01/12/2023] Open
Abstract
Proper structural organization of spiral ganglion (SG) innervation is crucial for normal hearing function. However, molecular mechanisms underlying the developmental formation of this precise organization remain not well understood. Here, we report in the developing mouse cochlea that deleted in colorectal cancer (Dcc) contributes to the proper organization of spiral ganglion neurons (SGNs) within the Rosenthal's canal and of SGN projections toward both the peripheral and central auditory targets. In Dcc mutant embryos, mispositioning of SGNs occurred along the peripheral auditory pathway with misrouted afferent fibers and reduced synaptic contacts with hair cells. The central auditory pathway simultaneously exhibited similar defective phenotypes as in the periphery with abnormal exit of SGNs from the Rosenthal's canal towards central nuclei. Furthermore, the axons of SGNs ascending into the cochlear nucleus had disrupted bifurcation patterns. Thus, Dcc is necessary for establishing the proper spatial organization of SGNs and their fibers in both peripheral and central auditory pathways, through controlling axon targeting and cell migration. Our results suggest that Dcc plays an important role in the developmental formation of peripheral and central auditory circuits, and its mutation may contribute to sensorineural hearing loss.
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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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Coate TM, Spita NA, Zhang KD, Isgrig KT, Kelley MW. Neuropilin-2/Semaphorin-3F-mediated repulsion promotes inner hair cell innervation by spiral ganglion neurons. eLife 2015; 4. [PMID: 26302206 PMCID: PMC4566076 DOI: 10.7554/elife.07830] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 08/22/2015] [Indexed: 12/18/2022] Open
Abstract
Auditory function is dependent on the formation of specific innervation patterns between mechanosensory hair cells (HCs) and afferent spiral ganglion neurons (SGNs). In particular, type I SGNs must precisely connect with inner HCs (IHCs) while avoiding connections with nearby outer HCs (OHCs). The factors that mediate these patterning events are largely unknown. Using sparse-labeling and time-lapse imaging, we visualized for the first time the behaviors of developing SGNs including active retraction of processes from OHCs, suggesting that some type I SGNs contact OHCs before forming synapses with IHCs. In addition, we demonstrate that expression of Semaphorin-3F in the OHC region inhibits type I SGN process extension by activating Neuropilin-2 receptors expressed on SGNs. These results suggest a model in which cochlear innervation patterns by type I SGNs are determined, at least in part, through a Semaphorin-3F-mediated inhibitory signal that impedes processes from extending beyond the IHC region. DOI:http://dx.doi.org/10.7554/eLife.07830.001 The process of hearing begins when sound waves enter the outer ear, causing the eardrum to vibrate. The three small bones of the middle ear pass these vibrations on to the cochlea, a fluid-filled structure shaped like a spiral. Tiny hair cells inside the cochlea move in response to the vibrations and convert them into electrical signals, which are transmitted by cells called spiral ganglion neurons (SGNs) to the brain. Hair cells can be divided into ‘inner’ and ‘outer’ hair cells. Inner hair cells transmit most of the information about a sound to the brain, via connections with type I SGNs. Outer hair cells are thought to amplify sound and connect to type II SGNs. How the type I and II SGNs connect to the correct type of hair cell as the ear develops is not well understood, despite these connections being essential for hearing. Coate et al. have now used time-lapse imaging and fixed specimens to follow individually labeled SGNs as they establish these connections within the cochlea of a mouse embryo. Although the type I SGNs ultimately formed connections with inner hair cells, many of them made contact with outer hair cells first. These contacts were short-lived thanks to a protein found near the outer hair cells, named Semaphorin-3F. This protein repels the type I SGNs by activating a receptor on their surface called Neuropilin-2, and so directs the type I SGNs towards the inner hair cells. One of the mysteries that remains to be solved is how type II SGNs are ‘permitted’ to extend into the outer hair cell region, even though they are also confronted by Semaphorin-3F. In addition, it will also be important to determine how SGNs adapt to cues from different Semaphorins from different parts of the cochlea as they navigate into different hair cell regions. DOI:http://dx.doi.org/10.7554/eLife.07830.002
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Affiliation(s)
- Thomas M Coate
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, Bethesda, United States
| | - Nathalie A Spita
- Department of Biology, Georgetown University, Washington, United States
| | - Kaidi D Zhang
- Department of Biology, Georgetown University, Washington, United States
| | - Kevin T Isgrig
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, Bethesda, United States
| | - Matthew W Kelley
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, Bethesda, United States
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