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Li Q, Cui C, Liao R, Yin X, Wang D, Cheng Y, Huang B, Wang L, Yan M, Zhou J, Zhao J, Tang W, Wang Y, Wang X, Lv J, Li J, Li H, Shu Y. The pathogenesis of common Gjb2 mutations associated with human hereditary deafness in mice. Cell Mol Life Sci 2023; 80:148. [PMID: 37178259 PMCID: PMC10182940 DOI: 10.1007/s00018-023-04794-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 03/31/2023] [Accepted: 04/28/2023] [Indexed: 05/15/2023]
Abstract
Mutations in GJB2 (Gap junction protein beta 2) are the most common genetic cause of non-syndromic hereditary deafness in humans, especially the 35delG and 235delC mutations. Owing to the homozygous lethality of Gjb2 mutations in mice, there are currently no perfect mouse models carrying Gjb2 mutations derived from patients for mimicking human hereditary deafness and for unveiling the pathogenesis of the disease. Here, we successfully constructed heterozygous Gjb2+/35delG and Gjb2+/235delC mutant mice through advanced androgenic haploid embryonic stem cell (AG-haESC)-mediated semi-cloning technology, and these mice showed normal hearing at postnatal day (P) 28. A homozygous mutant mouse model, Gjb235delG/35delG, was then generated using enhanced tetraploid embryo complementation, demonstrating that GJB2 plays an indispensable role in mouse placenta development. These mice exhibited profound hearing loss similar to human patients at P14, i.e., soon after the onset of hearing. Mechanistic analyses showed that Gjb2 35delG disrupts the function and formation of intercellular gap junction channels of the cochlea rather than affecting the survival and function of hair cells. Collectively, our study provides ideal mouse models for understanding the pathogenic mechanism of DFNB1A-related hereditary deafness and opens up a new avenue for investigating the treatment of this disease.
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Affiliation(s)
- Qing Li
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China.
| | - Chong Cui
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Rongyu Liao
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Xidi Yin
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Daqi Wang
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Yanbo Cheng
- School of Life Science and Technology, Shanghai Tech University, Shanghai, China
| | - Bowei Huang
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Liqin Wang
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Meng Yan
- School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China
| | - Jinan Zhou
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Jingjing Zhao
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Wei Tang
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Yingyi Wang
- School of Life Science and Technology, Shanghai Tech University, Shanghai, China
| | | | - Jun Lv
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- Institutes of Biomedical Sciences, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Jinsong Li
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
- School of Life Science and Technology, Shanghai Tech University, Shanghai, China
- School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China
| | - Huawei Li
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China.
- Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China.
| | - Yilai Shu
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China.
- Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China.
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Transcriptome-Wide Analysis Reveals a Role for Extracellular Matrix and Integrin Receptor Genes in Otic Neurosensory Differentiation from Human iPSCs. Int J Mol Sci 2021; 22:ijms221910849. [PMID: 34639189 PMCID: PMC8509699 DOI: 10.3390/ijms221910849] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/24/2021] [Accepted: 09/29/2021] [Indexed: 12/27/2022] Open
Abstract
We analyzed transcriptomic data from otic sensory cells differentiated from human induced pluripotent stem cells (hiPSCs) by a previously described method to gain new insights into the early human otic neurosensory lineage. We identified genes and biological networks not previously described to occur in the human otic sensory developmental cell lineage. These analyses identified and ranked genes known to be part of the otic sensory lineage program (SIX1, EYA1, GATA3, etc.), in addition to a number of novel genes encoding extracellular matrix (ECM) (COL3A1, COL5A2, DCN, etc.) and integrin (ITG) receptors (ITGAV, ITGA4, ITGA) for ECM molecules. The results were confirmed by quantitative PCR analysis of a comprehensive panel of genes differentially expressed during the time course of hiPSC differentiation in vitro. Immunocytochemistry validated results for select otic and ECM/ITG gene markers in the in vivo human fetal inner ear. Our screen shows ECM and ITG gene expression changes coincident with hiPSC differentiation towards human otic neurosensory cells. Our findings suggest a critical role of ECM-ITG interactions with otic neurosensory lineage genes in early neurosensory development and cell fate determination in the human fetal inner ear.
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Hou K, Jiang H, Karim MR, Zhong C, Xu Z, Liu L, Guan M, Shao J, Huang X. A Critical E-box in Barhl1 3' Enhancer Is Essential for Auditory Hair Cell Differentiation. Cells 2019; 8:cells8050458. [PMID: 31096644 PMCID: PMC6562609 DOI: 10.3390/cells8050458] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 05/06/2019] [Accepted: 05/07/2019] [Indexed: 02/05/2023] Open
Abstract
Barhl1, a mouse homologous gene of Drosophila BarH class homeobox genes, is highly expressed within the inner ear and crucial for the long-term maintenance of auditory hair cells that mediate hearing and balance, yet little is known about the molecular events underlying Barhl1 regulation and function in hair cells. In this study, through data mining and in vitro report assay, we firstly identified Barhl1 as a direct target gene of Atoh1 and one E-box (E3) in Barhl1 3’ enhancer is crucial for Atoh1-mediated Barhl1 activation. Then we generated a mouse embryonic stem cell (mESC) line carrying disruptions on this E3 site E-box (CAGCTG) using CRISPR/Cas9 technology and this E3 mutated mESC line is further subjected to an efficient stepwise hair cell differentiation strategy in vitro. Disruptions on this E3 site caused dramatic loss of Barhl1 expression and significantly reduced the number of induced hair cell-like cells, while no affections on the differentiation toward early primitive ectoderm-like cells and otic progenitors. Finally, through RNA-seq profiling and gene ontology (GO) enrichment analysis, we found that this E3 box was indispensable for Barhl1 expression to maintain hair cell development and normal functions. We also compared the transcriptional profiles of induced cells from CDS mutated and E3 mutated mESCs, respectively, and got very consistent results except the Barhl1 transcript itself. These observations indicated that Atoh1-mediated Barhl1 expression could have important roles during auditory hair cell development. In brief, our findings delineate the detail molecular mechanism of Barhl1 expression regulation in auditory hair cell differentiation.
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Affiliation(s)
- Kun Hou
- Institute of Cell and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
| | - Hui Jiang
- Institute of Cell and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
| | - Md Rezaul Karim
- Institute of Cell and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
- Department of Biotechnology and Genetic Engineering, Faculty of Biological Sciences, Islamic University, Kushtia 7003, Bangladesh.
| | - Chao Zhong
- Institute of Cell and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
| | - Zhouwen Xu
- Institute of Cell and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
| | - Lin Liu
- Institute of Cell and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
| | - Minxin Guan
- Institute of Genetics, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China.
| | - Jianzhong Shao
- Institute of Cell and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
- Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Hangzhou 310058, China.
| | - Xiao Huang
- Institute of Cell and Developmental Biology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
- Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Hangzhou 310058, China.
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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: 16] [Impact Index Per Article: 2.7] [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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Zhang J, Sun H, Salvi R, Ding D. Paraquat initially damages cochlear support cells leading to anoikis-like hair cell death. Hear Res 2018; 364:129-141. [PMID: 29563067 PMCID: PMC5984146 DOI: 10.1016/j.heares.2018.03.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 02/20/2018] [Accepted: 03/09/2018] [Indexed: 12/11/2022]
Abstract
Paraquat (PQ), one of the most widely used herbicides, is extremely dangerous because it generates the highly toxic superoxide radical. When paraquat was applied to cochlear organotypic cultures, it not only damaged the outer hair cells (OHCs) and inner hair cells (IHCs), but also caused dislocation of the hair cell rows. We hypothesized that the dislocation arose from damage to the support cells (SCs) that anchors hair cells within the epithelium. To test this hypothesis, rat postnatal cochlear cultures were treated with PQ. Shortly after PQ treatment, the rows of OHCs separated from one another and migrated radially away from IHCs suggesting loss of cell-cell adhesion that hold the hair cells in proper alignment. Hair cells dislocation was associated with extensive loss of SCs in the organ of Corti, loss of tympanic border cells (TBCs) beneath the basilar membrane, the early appearance of superoxide staining and caspase-8 labeling in SCs below the OHCs and disintegration of E-cadherin and β-catenin in the organ of Corti. Damage to the TBCs and SCs occurred prior to loss of OHC or IHC loss suggesting a form of detachment-induced apoptosis referred to as anoikis.
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Affiliation(s)
- Jianhui Zhang
- Department of Otorhinolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, China; Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, 14214, USA
| | - Hong Sun
- Department of Otorhinolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, China; Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, 14214, USA
| | - Richard Salvi
- Department of Otorhinolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, China; Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, 14214, USA; Department of Audiology and Speech-Language Pathology, Asia University, Taichung, Taiwan, ROC
| | - Dalian Ding
- Department of Otorhinolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, China; Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, 14214, USA.
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6
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Abstract
More than 80% of all cases of deafness are related to the death or degeneration of cochlear hair cells and the associated spiral ganglion neurons, and a lack of regeneration of these cells leads to permanent hearing loss. Therefore, the regeneration of lost hair cells is an important goal for the treatment of deafness. Atoh1 is a basic helix-loop-helix (bHLH) transcription factor that is critical in both the development and regeneration of cochlear hair cells. Atoh1 is transcriptionally regulated by several signaling pathways, including Notch and Wnt signalings. At the post-translational level, it is regulated through the ubiquitin-proteasome pathway. In vitro and in vivo studies have revealed that manipulation of these signaling pathways not only controls development, but also leads to the regeneration of cochlear hair cells after damage. Recent progress toward understanding the signaling networks involved in hair cell development and regeneration has led to the development of new strategies to replace lost hair cells. This review focuses on our current understanding of the signaling pathways that regulate Atoh1 in the cochlea.
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Affiliation(s)
- Yen-Fu Cheng
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02115, USA.,Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA.,Department of Medical Research, Taipei Veterans General Hospital, Taipei 112, Taiwan, China.,Department of Otolaryngology-Head and Neck Surgery, Taipei Veterans General Hospital, Taipei 112, Taiwan, China.,School of Medicine, Yang-Ming University, Taipei 112, Taiwan, China.,Department of Speech Language Pathology and Audiology, Taipei University of Nursing and Health Science, Taipei 112, Taiwan, China
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7
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Ladrech S, Eybalin M, Puel JL, Lenoir M. Epithelial-mesenchymal transition, and collective and individual cell migration regulate epithelial changes in the amikacin-damaged organ of Corti. Histochem Cell Biol 2017; 148:129-142. [PMID: 28365859 DOI: 10.1007/s00418-017-1548-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2017] [Indexed: 12/23/2022]
Abstract
Characterizing the microenvironment of a damaged organ of Corti and identifying the basic mechanisms involved in subsequent epithelial reorganization are critical for improving the outcome of clinical therapies. In this context, we studied the expression of a variety of cell markers related to cell shape, cell adhesion and cell plasticity in the rat organ of Corti poisoned with amikacin. Our results indicate that, after severe outer hair cell losses, the cytoarchitectural reorganization of the organ of Corti implicates epithelial-mesenchymal transition mechanisms and involves both collective and individual cell migratory processes. The results also suggest that both root cells and infiltrated fibroblasts participate in the homeostasis of the damaged epithelium, and that the flat epithelium that may emerge offers biological opportunities for late regenerative therapies.
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Affiliation(s)
- Sabine Ladrech
- INSERM U1051, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, 80 rue Augustin Fliche, 34091, Montpellier Cedex 5, France.,University of Montpellier, Montpellier, France
| | - Michel Eybalin
- INSERM U1051, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, 80 rue Augustin Fliche, 34091, Montpellier Cedex 5, France.,University of Montpellier, Montpellier, France
| | - Jean-Luc Puel
- INSERM U1051, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, 80 rue Augustin Fliche, 34091, Montpellier Cedex 5, France.,University of Montpellier, Montpellier, France
| | - Marc Lenoir
- INSERM U1051, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, 80 rue Augustin Fliche, 34091, Montpellier Cedex 5, France. .,University of Montpellier, Montpellier, France.
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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: 49] [Impact Index Per Article: 5.4] [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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9
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Maass JC, Gu R, Basch ML, Waldhaus J, Lopez EM, Xia A, Oghalai JS, Heller S, Groves AK. Changes in the regulation of the Notch signaling pathway are temporally correlated with regenerative failure in the mouse cochlea. Front Cell Neurosci 2015; 9:110. [PMID: 25873862 PMCID: PMC4379755 DOI: 10.3389/fncel.2015.00110] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 03/10/2015] [Indexed: 12/20/2022] Open
Abstract
Sensorineural hearing loss is most commonly caused by the death of hair cells in the organ of Corti, and once lost, mammalian hair cells do not regenerate. In contrast, other vertebrates such as birds can regenerate hair cells by stimulating division and differentiation of neighboring supporting cells. We currently know little of the genetic networks which become active in supporting cells when hair cells die and that are activated in experimental models of hair cell regeneration. Several studies have shown that neonatal mammalian cochlear supporting cells are able to trans-differentiate into hair cells when cultured in conditions in which the Notch signaling pathway is blocked. We now show that the ability of cochlear supporting cells to trans-differentiate declines precipitously after birth, such that supporting cells from six-day-old mouse cochlea are entirely unresponsive to a blockade of the Notch pathway. We show that this trend is seen regardless of whether the Notch pathway is blocked with gamma secretase inhibitors, or by antibodies against the Notch1 receptor, suggesting that the action of gamma secretase inhibitors on neonatal supporting cells is likely to be by inhibiting Notch receptor cleavage. The loss of responsiveness to inhibition of the Notch pathway in the first postnatal week is due in part to a down-regulation of Notch receptors and ligands, and we show that this down-regulation persists in the adult animal, even under conditions of noise damage. Our data suggest that the Notch pathway is used to establish the repeating pattern of hair cells and supporting cells in the organ of Corti, but is not required to maintain this cellular mosaic once the production of hair cells and supporting cells is completed. Our results have implications for the proposed used of Notch pathway inhibitors in hearing restoration therapies.
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Affiliation(s)
- Juan C Maass
- Department of Neuroscience, Baylor College of Medicine Houston, TX, USA ; Department of Otolaryngology, Hospital Clínico Universidad de Chile Santiago, Chile ; Interdisciplinary Program of Physiology and Biophysics, ICBM Universidad de Chile Santiago, Chile ; Department of Otolaryngology, Clínica Alemana de Santiago, Facultad de Medicina Clínica Alemana-Universidad del Desarrollo Santiago, Chile
| | - Rende Gu
- Department of Neuroscience, Baylor College of Medicine Houston, TX, USA
| | - Martin L Basch
- Department of Neuroscience, Baylor College of Medicine Houston, TX, USA
| | - Joerg Waldhaus
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine Palo Alto, CA, USA
| | | | - Anping Xia
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine Palo Alto, CA, USA
| | - John S Oghalai
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine Palo Alto, CA, USA
| | - Stefan Heller
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine Palo Alto, CA, USA
| | - Andrew K Groves
- Department of Neuroscience, Baylor College of Medicine Houston, TX, USA ; Department of Molecular and Human Genetics, Baylor College of Medicine Houston, TX, USA ; Program in Developmental Biology, Baylor College of Medicine Houston, TX, USA
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10
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Agochukwu NB, Solomon BD, Muenke M. Hearing loss in syndromic craniosynostoses: introduction and consideration of mechanisms. Am J Audiol 2014; 23:135-41. [PMID: 24686979 DOI: 10.1044/2014_aja-13-0036] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
PURPOSE There are a number of craniosynostosis syndromes with hearing loss-including Muenke, Apert, Pfeiffer, Crouzon, Beare-Stevenson, Crouzon with acanthosis nigricans, and Jackson-Weiss syndromes-that result from mutations in the fibroblast growth factor receptor (FGFR) genes. Studies of FGFRs and their ligands, fibroblast growth factors (FGFs), have revealed clues to the precise contribution of aberrant FGFR signaling to inner ear morphogenesis and the hearing loss encountered in craniosynostoses. The purpose of this article is to review basic studies of FGFRs with emphasis on their function and expression in the inner ear and surrounding structures. METHOD A Medline search was performed to find basic science articles regarding FGFR, their ligands, and their expression and relevant mouse models. Additional items searched included clinical descriptions and studies of individuals with FGFR-related craniosynostosis syndromes. RESULTS The FGF signaling pathway is essential for the morphogensis and proper function of the inner ear and auditory sensory epithelium. CONCLUSION The variable auditory phenotypes seen in individuals with Muenke syndrome may have a genetic basis, likely due to multiple interacting factors in the genetic environment or modifying factors. Further analysis and studies of mouse models of Muenke syndrome, in particular, may provide clues to the specific effects of the defining mutation in FGFR3 in the inner ear not only at birth but also into adulthood. In particular, investigations into these models may give insight into the variable expression and incomplete penetrance of this phenotype.
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Affiliation(s)
- Nneamaka B. Agochukwu
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD
- Clinical Research Training Program, National Institutes of Health, Bethesda, MD
| | - Benjamin D. Solomon
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD
| | - Maximilian Muenke
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD
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Coate TM, Kelley MW. Making connections in the inner ear: recent insights into the development of spiral ganglion neurons and their connectivity with sensory hair cells. Semin Cell Dev Biol 2013; 24:460-9. [PMID: 23660234 PMCID: PMC3690159 DOI: 10.1016/j.semcdb.2013.04.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 04/15/2013] [Indexed: 01/18/2023]
Abstract
In mammals, auditory information is processed by the hair cells (HCs) located in the cochlea and then rapidly transmitted to the CNS via a specialized cluster of bipolar afferent connections known as the spiral ganglion neurons (SGNs). Although many anatomical aspects of SGNs are well described, the molecular and cellular mechanisms underlying their genesis, how they are precisely arranged along the cochlear duct, and the guidance mechanisms that promote the innervation of their hair cell targets are only now being understood. Building upon foundational studies of neurogenesis and neurotrophins, we review here new concepts and technologies that are helping to enrich our understanding of the development of the nervous system within the inner ear.
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Affiliation(s)
- Thomas M Coate
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA.
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12
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Inner ear supporting cells: rethinking the silent majority. Semin Cell Dev Biol 2013; 24:448-59. [PMID: 23545368 DOI: 10.1016/j.semcdb.2013.03.009] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 03/21/2013] [Indexed: 11/21/2022]
Abstract
Sensory epithelia of the inner ear contain two major cell types: hair cells and supporting cells. It has been clear for a long time that hair cells play critical roles in mechanoreception and synaptic transmission. In contrast, until recently the more abundant supporting cells were viewed as serving primarily structural and homeostatic functions. In this review, we discuss the growing information about the roles that supporting cells play in the development, function and maintenance of the inner ear, their activities in pathological states, their potential for hair cell regeneration, and the mechanisms underlying these processes.
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13
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Lin J, Yan X, Wang C, Talabattula VAN, Guo Z, Rolfs A, Luo J. Expression patterns of the ADAMs in early developing chicken cochlea. Dev Growth Differ 2013; 55:368-76. [PMID: 23496030 DOI: 10.1111/dgd.12051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 01/29/2013] [Accepted: 02/04/2013] [Indexed: 12/30/2022]
Abstract
Members of the ADAM (a disintegrin and metalloprotease) family are type I transmembrane proteins involved in biological processes of proteolysis, cell adhesion, cell-matrix interaction, as well as in the intracellular signaling transduction. In the present study, expression patterns of seven members of the ADAM family were investigated at the early stages of the developing cochlea by in situ hybridization. The results show that each individual ADAM is expressed and regulated in the early developing cochlea. ADAM9, ADAM10, ADAM17, and ADAM23 are initially and widely expressed in the otic vesicle at embryonic day 2.5 (E2.5) and in the differential elements of the cochlear duct at E9, while ADAM12 is expressed in acoustic ganglion cells at E7. ADAM22 is detectable in cochlear ganglion cells as early as from E4 and in the basilar papilla from E7. Therefore, the present study extends our previous results and suggests that ADAMs also play a role in the early cochlear development.
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Affiliation(s)
- Juntang Lin
- Key Laboratory for Medical Tissue Regeneration of Henan Province, Xinxiang Medical University, Xinxiang City, 453003, Henan, China
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14
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Roeseler DA, Sachdev S, Buckley DM, Joshi T, Wu DK, Xu D, Hannink M, Waters ST. Elongation factor 1 alpha1 and genes associated with Usher syndromes are downstream targets of GBX2. PLoS One 2012; 7:e47366. [PMID: 23144817 PMCID: PMC3493575 DOI: 10.1371/journal.pone.0047366] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 09/12/2012] [Indexed: 11/18/2022] Open
Abstract
Gbx2 encodes a DNA-binding transcription factor that plays pivotal roles during embryogenesis. Gain-and loss-of-function studies in several vertebrate species have demonstrated a requirement for Gbx2 in development of the anterior hindbrain, spinal cord, inner ear, heart, and neural crest cells. However, the target genes through which GBX2 exerts its effects remain obscure. Using chromatin immunoprecipitation coupled with direct sequencing (ChIP-Seq) analysis in a human prostate cancer cell line, we identified cis-regulatory elements bound by GBX2 to provide insight into its direct downstream targets. The analysis revealed more than 286 highly significant candidate target genes, falling into various functional groups, of which 51% are expressed in the nervous system. Several of the top candidate genes include EEF1A1, ROBO1, PLXNA4, SLIT3, NRP1, and NOTCH2, as well as genes associated with the Usher syndrome, PCDH15 and USH2A, and are plausible candidates contributing to the developmental defects in Gbx2(-/-) mice. We show through gel shift analyses that sequences within the promoter or introns of EEF1A1, ROBO1, PCDH15, USH2A and NOTCH2, are directly bound by GBX2. Consistent with these in vitro results, analyses of Gbx2(-/-) embryos indicate that Gbx2 function is required for migration of Robo1-expressing neural crest cells out of the hindbrain. Furthermore, we show that GBX2 activates transcriptional activity through the promoter of EEF1A1, suggesting that GBX2 could also regulate gene expression indirectly via EEF1A. Taken together, our studies show that GBX2 plays a dynamic role in development and diseases.
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Affiliation(s)
- David A. Roeseler
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States of America
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
| | - Shrikesh Sachdev
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
- Department of Biochemistry, University of Missouri, Columbia, Missouri, United States of America
| | - Desire M. Buckley
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States of America
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
| | - Trupti Joshi
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
- Department of Computer Science, University of Missouri, Columbia, Missouri, United States of America
- Informatics Institute, University of Missouri, Columbia, Missouri, United States of America
| | - Doris K. Wu
- Laboratory of Molecular Biology, NIDCD, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Dong Xu
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
- Department of Computer Science, University of Missouri, Columbia, Missouri, United States of America
- Informatics Institute, University of Missouri, Columbia, Missouri, United States of America
| | - Mark Hannink
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
- Department of Biochemistry, University of Missouri, Columbia, Missouri, United States of America
| | - Samuel T. Waters
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States of America
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
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In vitro differentiation of mouse embryonic stem cells into inner ear hair cell-like cells using stromal cell conditioned medium. Cell Death Dis 2012; 3:e314. [PMID: 22622133 PMCID: PMC3366087 DOI: 10.1038/cddis.2012.56] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hearing loss is mainly caused by loss of sensory hair cells (HCs) in the organ of Corti or cochlea. Although embryonic stem (ES) cells are a promising source for cell therapy, little is known about the efficient generation of HC-like cells from ES cells. In the present study, we developed a single-medium culture method for growing embryoid bodies (EBs), in which conditioned medium (CM) from cultures of ST2 stromal cells (ST2-CM) was used for 14-day cultures of 4-day EBs. At the end of the 14-day cultures, up to 20% of the cells in EB outgrowths expressed HC-related markers, including Math1 (also known as Atoh1), myosin6, myosin7a, calretinin, α9AchR and Brn3c (also known as Pou4f3), and also showed formation of stereocilia-like structures. Further, we found that these cells were incorporated into the developing inner ear after transplantation into chick embryos. The present inner ear HC induction method using ST2-CM (HIST2 method) is quite simple and highly efficient to obtain ES-derived HC-like cells with a relatively short cultivation time.
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16
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O'Leary SJ, Richardson RR, McDermott HJ. Principles of design and biological approaches for improving the selectivity of cochlear implant electrodes. J Neural Eng 2009; 6:055002. [PMID: 19721188 DOI: 10.1088/1741-2560/6/5/055002] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The perceptual performance of cochlear implant recipients seems to have reached a plateau in recent years. This may be attributable to inadequate neural selectivity of available intracochlear electrodes, caused by current spread and electrode interactions. Attempts to improve electrode selectivity have included manipulating the number and configuration of electrodes that are stimulated at any one time, displacing perilymph from the cochlea to restrict current flow along the cochlea, and reducing the distance between electrodes and neurons. One experimental approach by which the distance between neurons and electrodes may be reduced is to use neurotrophic factors to promote the regeneration of the peripheral dendrites of auditory neurons and guide them towards intracochlear electrodes. The likely requirements of a system for regenerating auditory neurons towards the cochlear electrode include either a stable release of neurotrophin, or transient neurotrophin followed by electrical stimulation; a close proximity of electrode to osseous spiral lamina or a polymer to bridge the gap between the two; guidance signals to attract neurons towards the electrode; patterning of the electrode surface to direct dendrites to electrode contacts and a 'stop' signal to arrest regeneration once the electrode has been reached.
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Affiliation(s)
- Stephen J O'Leary
- Department of Otolaryngology, University of Melbourne, Royal Victorian Eye and Ear Hospital, Australia.
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17
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scn1bb, a zebrafish ortholog of SCN1B expressed in excitable and nonexcitable cells, affects motor neuron axon morphology and touch sensitivity. J Neurosci 2009; 28:12510-22. [PMID: 19020043 DOI: 10.1523/jneurosci.4329-08.2008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Voltage-gated Na(+) channels initiate and propagate action potentials in excitable cells. Mammalian Na(+) channels are composed of one pore-forming alpha-subunit and two beta-subunits. SCN1B encodes the Na(+) channel beta1-subunit that modulates channel gating and voltage dependence, regulates channel cell surface expression, and functions as a cell adhesion molecule (CAM). We recently identified scn1ba, a zebrafish ortholog of SCN1B. Here we report that zebrafish express a second beta1-like paralog, scn1bb. In contrast to the restricted expression of scn1ba mRNA in excitable cells, we detected scn1bb transcripts and protein in several ectodermal derivatives including neurons, glia, the lateral line, peripheral sensory structures, and tissues derived from other germ layers such as the pronephros. As expected for beta1-subunits, elimination of Scn1bb protein in vivo by morpholino knock-down reduced Na(+) current amplitudes in Rohon-Beard neurons of zebrafish embryos, consistent with effects observed in heterologous systems. Further, after Scn1bb knock-down, zebrafish embryos displayed defects in Rohon-Beard mediated touch sensitivity, demonstrating the significance of Scn1bb modulation of Na(+) current to organismal behavior. In addition to effects associated with Na(+) current modulation, Scn1bb knockdown produced phenotypes consistent with CAM functions. In particular, morpholino knock-down led to abnormal development of ventrally projecting spinal neuron axons, defasciculation of the olfactory nerve, and increased hair cell number in the inner ear. We propose that, in addition to modulation of electrical excitability, Scn1bb plays critical developmental roles by functioning as a CAM in the zebrafish embryonic nervous system.
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18
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Batts SA, Shoemaker CR, Raphael Y. Notch signaling and Hes labeling in the normal and drug-damaged organ of Corti. Hear Res 2009; 249:15-22. [PMID: 19185606 PMCID: PMC2796274 DOI: 10.1016/j.heares.2008.12.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Revised: 12/19/2008] [Accepted: 12/30/2008] [Indexed: 12/01/2022]
Abstract
During the development of the inner ear, the Notch cell signaling pathway is responsible for the specification of the pro-sensory domain and influences cell fate decisions. It is assumed that Notch signaling ends during maturity and cannot be reinitiated to alter the fate of new or existing cells in the organ of Corti. This is in contrast to non-mammalian species which reinitiate Delta 1-Notch1 signaling in response to trauma in the auditory epithelium, resulting in hair cell regeneration through transdifferentiation and/or mitosis. We report immunohistochemical data and Western protein analysis showing that in the aminoglycoside-damaged guinea pig organ of Corti, there is an increase in proteins involved in Notch activation occurring within 24h of a chemical hair cell lesion. The signaling response is characterized by the increased presence of Jagged1 ligand in pillar and Deiters cells, Notch1 signal in surviving supporting cell nuclei, and the absence of Jagged2 and Delta-like1. The pro-sensory bHLH protein Atoh1 was absent at all time points following an ototoxic lesion, while the repressor bHLH transcription factors Hes1 and Hes5 were detected in surviving supporting cell nuclei in the former inner and outer hair cell areas, respectively. Notch pathway proteins peaked at 2 weeks, decreased at 1 month, and nearly disappeared by 2 months. These results indicate that the mammalian auditory epithelium retains the ability to regulate Notch signaling and Notch-dependent Hes activity in response to cellular trauma and that the signaling is transient. Additionally, since Hes activity antagonizes the transcription of pro-sensory Atoh1, the presence of Hes after a lesion may prohibit the occurrence of transdifferentiation in the surviving supporting cells.
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Affiliation(s)
- Shelley A. Batts
- Kresge Hearing Research Institute, University of Michigan, Ann Arbor, Michigan, USA
- Neuroscience Program, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Yehoash Raphael
- Kresge Hearing Research Institute, University of Michigan, Ann Arbor, Michigan, USA
- Neuroscience Program, University of Michigan, Ann Arbor, Michigan, USA
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19
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Hedgehog signaling regulates sensory cell formation and auditory function in mice and humans. J Neurosci 2008; 28:7350-8. [PMID: 18632939 DOI: 10.1523/jneurosci.0312-08.2008] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Auditory perception is mediated through a finite number of mechanosensory hair cells located in a specialized sensory epithelium within the inner ear. The formation of the appropriate number of hair cells and the location of those cells is crucial for normal auditory function. However, the factors that regulate the formation of this epithelium remain poorly understood. Truncating mutations in the transcription factor GLI3, a downstream effector of the Hedgehog (HH) pathway, lead to a partial loss of HH signaling and cause Pallister-Hall syndrome (PHS). Here, we report that cochleae from a mouse model of PHS (Gli3(Delta699)), which produces only the truncated, repressor form of GLI3, have a variably penetrant phenotype that includes an increase in the size of the sensory epithelium and the development of large ectopic sensory patches in Kölliker's organ (KO). Consistent with the mouse model, some PHS individuals exhibit hearing loss across a broad range of frequencies. Moreover, inhibition of HH signaling in vitro results in an increase in the size of the prosensory domain, a precursor population that gives rise to the sensory epithelium, whereas treatment with Sonic hedgehog (SHH) inhibits prosensory formation. Finally, we demonstrate that HH signaling within the cochlea regulates expression of prosensory markers and that the effects of HH in KO are dependent on activation of Notch, an inducer of prosensory fate. These results suggest that HH signaling plays a key role in the specification, size, and location of the prosensory domain, and therefore of hair cells, within the cochlea.
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Abstract
In this study, we demonstrate that eight classic cadherins are differentially expressed in distinct anatomical regions of the cochlea during late stages of chicken embryonic development. Cadherin-6B is expressed in hair cells and spindle-shaped cells, while cadherin-8 mRNA is found only in supporting cells. Cadherin-11 is widely expressed not only in mesenchymal cell around the cochlea, but also in supporting cells and homogene cells. N-cadherin is found in the sensory epithelium, the neurons of the acoustic ganglion and on their neurites that target the hair cells. Three closely related cadherins (cadherin-7, cadherin-19, and cadherin-20) are expressed in a partially complementary manner in spindle-shaped cells and acoustic ganglion cells. R-cadherin is observed in homogene cells, acoustic ganglion cells, and their projections to hair cells. The expression of classic cadherins in the developing cochlea suggests a role for cadherins in the development of the cochlea.
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Affiliation(s)
- Jiankai Luo
- Institute of Anatomy I, Friedrich Schiller University Jena, Jena, Germany.
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21
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Davies D. Temporal and spatial regulation of alpha6 integrin expression during the development of the cochlear-vestibular ganglion. J Comp Neurol 2007; 502:673-82. [PMID: 17436285 DOI: 10.1002/cne.21302] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The neurons of the cochlear-vestibular ganglion (CVG) that innervate the sensory hair cells of the inner ear are derived from the otic epithelium early in development. Neuroblasts detach from neighboring cells, migrate into the mesenchyme where they coalesce to form the ganglion complex, then send processes back into the epithelium. Cell migration and neuronal process formation involve changes in cellular interactions with other cells and proteins in the extracellular matrix that are orchestrated by cell surface-expressed adhesion molecules, including the integrins. I studied the expression pattern of the alpha6 integrin subunit during the early development of the CVG using immunohistochemistry and reverse-transcriptase polymerase chain reaction (RT-PCR) in murine tissue sections, otocyst, and ganglion explants. At embryonic day (E)10.5 alpha6 integrin was expressed in the otic epithelium but not in migrating neuroblasts. Importantly, the loss of alpha6 was associated with exit from the epithelium, not neuronal determination, revealing differentiation cues acutely associated with the cellular environment. Markers of glial and neuronal phenotype showed that alpha6-expressing cells present in the CVG at this stage were glia of neural crest origin. By E12.5 alpha6 expression in the ganglion increased alongside the elaboration of neuronal processes. Immunohistochemistry applied to otocyst cultures in the absence of glia revealed that neuronal processes remained alpha6-negative at this developmental stage and confirmed that alpha6 was expressed by closely apposed glia. The spatiotemporal modulation of alpha6 expression suggests changing roles for this integrin during the early development of inner ear innervation.
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Affiliation(s)
- Dawn Davies
- Department of Physiology, University of Bristol, School of Medical Sciences, University Walk, Bristol, BS8 1TD, UK.
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22
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Liu JJ, Shin JH, Hyrc KL, Liu S, Lei D, Holley MC, Bao J. Stem cell therapy for hearing loss: Math1 overexpression in VOT-E36 cells. Otol Neurotol 2007; 27:414-21. [PMID: 16639283 DOI: 10.1097/00129492-200604000-00020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS VOT-E36 cells acquire mechanosensitivity after mammalian atonal homolog 1 (Math1) overexpression. BACKGROUND VOT-E36 cells are derived from a population of epithelial cells in the ventral region of the otocyst at embryonic Day 10.5, before hair cell differentiation. These cells express a number of specific molecular markers for hair cells under both proliferation and differentiation states. Overexpression of Math1 can convert nonsensory epithelial cells into hair cells in the cochlea. Based on this information, we tested whether VOT-E36 cells can be converted into hair cells by Math1 overexpression. METHODS Using reverse transcriptase-polymerase chain reaction-based analysis, we first compared the expression patterns of various molecular markers for hair cell development in VOT-E36 cells between proliferation and differentiation states, and also before and after overexpression of Math1. Subsequently, with a standard calcium imaging method, we examined whether VOT-E36 cells overexpressing Math1 could detect mechanical vibrations and activate spiral ganglion neurons in a coculture model. In addition, using confocal and scanning electron microscopes, we examined morphologic changes of VOT-E36 cells after Math1 overexpression. RESULTS Consistent with previous reports, this study has shown that VOT-E36 cells express a number of specific molecular markers for hair cells in both proliferation and differentiation states. Under appropriate culture conditions, Math1 is transiently expressed in this cell line during conditional differentiation. In VOT-E36 cells overexpressing Math1, the normal expression pattern of certain molecular markers for mature hair cells is partially restored. Interestingly, after coculture with spiral ganglion neurons, VOT-E36 cells overexpressing Math1 are able to respond to mechanical vibrations and activate spiral ganglion neurons. Possible molecular mechanisms underlying this novel finding have been explored. CONCLUSION Math1 overexpression can partially restore presumably downstream signaling cascades for normal hair cell differentiation in VOT-E36 cells, which are able to detect mechanical vibrations after being cocultured with spiral ganglion neurons.
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Affiliation(s)
- Jan-Jan Liu
- Department of Otolaryngology, Center for Aging, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Wang Y, Nathans J. Tissue/planar cell polarity in vertebrates: new insights and new questions. Development 2007; 134:647-58. [PMID: 17259302 DOI: 10.1242/dev.02772] [Citation(s) in RCA: 341] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This review focuses on the tissue/planar cell polarity (PCP) pathway and its role in generating spatial patterns in vertebrates. Current evidence suggests that PCP integrates both global and local signals to orient diverse structures with respect to the body axes. Interestingly, the system acts on both subcellular structures, such as hair bundles in auditory and vestibular sensory neurons, and multicellular structures, such as hair follicles. Recent work has shown that intriguing connections exist between the PCP-based orienting system and left-right asymmetry, as well as between the oriented cell movements required for neural tube closure and tubulogenesis. Studies in mice, frogs and zebrafish have revealed that similarities, as well as differences, exist between PCP in Drosophila and vertebrates.
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Affiliation(s)
- Yanshu Wang
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Abelló G, Khatri S, Giráldez F, Alsina B. Early regionalization of the otic placode and its regulation by the Notch signaling pathway. Mech Dev 2007; 124:631-45. [PMID: 17532192 DOI: 10.1016/j.mod.2007.04.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Revised: 04/11/2007] [Accepted: 04/13/2007] [Indexed: 01/30/2023]
Abstract
Otic neuronal precursors are the first cells to be specified and do so in the anterior domain of the otic placode, the proneural domain. In the present study, we have explored the early events of otic proneural regionalization in relation to the activity of the Notch signaling pathway. The proneural domain was characterized by the expression of Sox3, Fgf10 and members of the Notch pathway such as Delta1, Hes5 and Lunatic Fringe. The complementary non-neural domain expressed two patterning genes, Lmx1b and Iroquois1, and the members of the Notch pathway, Serrate1 and Hairy1. Fate map studies and double injections with DiI/DiO showed that labeled cells remained confined to anterior or posterior territories with limited cell intermingling. To explore whether Notch signaling pathway plays a role in the initial regionalization of the otic placode, Notch activity was blocked by a gamma-secretase inhibitor (DAPT). Notch blockade induced the expansion of non-neural genes, Lmx1 and Iroquois1, into the proneural domain. Combined gene expression and DiI experiments showed that these effects were not due to migration of non-neural cells into the proneural domain, suggesting that Notch activity regulates the expression of non-neural genes. This was further confirmed by the electroporation of a dominant-negative form of the Mastermind-like1 gene that caused the up-regulation of Lmx1 within the proneural domain. In addition, Notch pathway was involved in neuronal precursor selection, probably by a classical mechanism of lateral inhibition. We propose that the regionalization of the otic domain into a proneural and a non-neural territory is a very early event in otic development, and that Notch signaling activity is required to exclude the expression of non-neural genes from the proneural territory.
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Affiliation(s)
- Gina Abelló
- DCEXS-Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003 Barcelona, Spain
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Kim TS, Nakagawa T, Kitajiri SI, Endo T, Takebayashi S, Iguchi F, Kita T, Tamura T, Ito J. Disruption and restoration of cell-cell junctions in mouse vestibular epithelia following aminoglycoside treatment. Hear Res 2006; 205:201-9. [PMID: 15953529 DOI: 10.1016/j.heares.2005.03.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Accepted: 03/18/2005] [Indexed: 11/16/2022]
Abstract
The intracellular junction complexes, which consist of tight junctions (TJ), adherens junctions (AJ), and desmosomes, mediate cell-cell adhesion in epithelial cells. E-cadherin, which is a major component of AJ, plays a role not only in the maintenance of cell-cell junctions, but also in repressing cell proliferation. In this study, we examined changes of E-cadherin expression in mouse vestibular epithelia following local application of neomycin using immunohistochemistry and western blotting, and morphology of cell-cell junctions by transmission electron microscopy (TEM). Immunohistochemistry and western blotting revealed down-expression of E-cadherin and its consecutive recovery. TEM demonstrated temporal disruption of cell-cell junctions. Morphology of cell-cell junctions was more rapidly restored than recovery of E-cadherin expression. Transient disruption of cell-cell junctions and down-expression of E-cadherin is a rational response for the deletion of dying hair cells, and may be associated with a limited capacity for cell proliferations in mammalian vestibular epithelia following their rapid restoration.
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MESH Headings
- Adherens Junctions/drug effects
- Adherens Junctions/physiology
- Adherens Junctions/ultrastructure
- Analysis of Variance
- Animals
- Anti-Bacterial Agents/toxicity
- Apoptosis/drug effects
- Blotting, Western
- Cadherins/analysis
- Cadherins/biosynthesis
- Cadherins/physiology
- Calbindin 2
- Case-Control Studies
- Cell Adhesion/drug effects
- Cell Adhesion/physiology
- Hair Cells, Auditory/cytology
- Hair Cells, Auditory/drug effects
- Hair Cells, Auditory/metabolism
- Hearing Loss, Sensorineural/chemically induced
- Hearing Loss, Sensorineural/prevention & control
- Immunohistochemistry
- Intercellular Junctions/drug effects
- Intercellular Junctions/pathology
- Intercellular Junctions/physiology
- Mice
- Mice, Inbred C57BL
- Microscopy, Electron, Transmission
- Models, Animal
- Neomycin/toxicity
- S100 Calcium Binding Protein G/analysis
- Saccule and Utricle/drug effects
- Saccule and Utricle/metabolism
- Saccule and Utricle/pathology
- Tight Junctions/drug effects
- Tight Junctions/physiology
- Tight Junctions/ultrastructure
- Vestibule, Labyrinth/cytology
- Vestibule, Labyrinth/drug effects
- Vestibule, Labyrinth/metabolism
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Affiliation(s)
- Tae-Soo Kim
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Sakyo-ku, 606-8507 Kyoto, Japan.
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26
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Holley MC. Keynote review: The auditory system, hearing loss and potential targets for drug development. Drug Discov Today 2005; 10:1269-82. [PMID: 16214671 DOI: 10.1016/s1359-6446(05)03595-6] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
There is a huge potential market for the treatment of hearing loss. Drugs are already available to ameliorate predictable, damaging effects of excessive noise and ototoxic drugs. The biggest challenge now is to develop drug-based treatments for regeneration of sensory cells following noise-induced and age-related hearing loss. This requires careful consideration of the physiological mechanisms of hearing loss and identification of key cellular and molecular targets. There are many molecular cues for the discovery of suitable drug targets and a full range of experimental resources are available for initial screening through to functional analysis in vivo. There is now an unparalleled opportunity for translational research.
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Affiliation(s)
- Matthew C Holley
- Department of Biomedical Sciences, Addison Building, Western Bank, Sheffield S10 2TN, UK.
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27
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Shim K, Minowada G, Coling DE, Martin GR. Sprouty2, a mouse deafness gene, regulates cell fate decisions in the auditory sensory epithelium by antagonizing FGF signaling. Dev Cell 2005; 8:553-64. [PMID: 15809037 DOI: 10.1016/j.devcel.2005.02.009] [Citation(s) in RCA: 203] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2005] [Revised: 02/11/2005] [Accepted: 02/22/2005] [Indexed: 11/20/2022]
Abstract
The auditory sensory epithelium (organ of Corti), where sound waves are converted to electrical signals, comprises a highly ordered array of sensory receptor (hair) cells and nonsensory supporting cells. Here, we report that Sprouty2, which encodes a negative regulator of signaling via receptor tyrosine kinases, is required for normal hearing in mice, and that lack of SPRY2 results in dramatic perturbations in organ of Corti cytoarchitecture: instead of two pillar cells, there are three, resulting in the formation of an ectopic tunnel of Corti. We demonstrate that these effects are due to a postnatal cell fate transformation of a Deiters' cell into a pillar cell. Both this cell fate change and hearing loss can be partially rescued by reducing Fgf8 gene dosage in Spry2 null mutant mice. Our results provide evidence that antagonism of FGF signaling by SPRY2 is essential for establishing the cytoarchitecture of the organ of Corti and for hearing.
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Affiliation(s)
- Katherine Shim
- Department of Anatomy and Program in Developmental Biology, School of Medicine, University of California, San Francisco, California 94143, USA
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28
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Lagziel A, Ahmed ZM, Schultz JM, Morell RJ, Belyantseva IA, Friedman TB. Spatiotemporal pattern and isoforms of cadherin 23 in wild type and waltzer mice during inner ear hair cell development. Dev Biol 2005; 280:295-306. [PMID: 15882574 DOI: 10.1016/j.ydbio.2005.01.015] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Revised: 01/07/2005] [Accepted: 01/11/2005] [Indexed: 10/25/2022]
Abstract
Mutant alleles of the gene encoding cadherin 23 are associated with Usher syndrome type 1 (USH1D), isolated deafness (DFNB12) in humans, and deafness and circling behavior in waltzer (v) mice. Stereocilia of waltzer mice are disorganized and the kinocilia misplaced, indicating the importance of cadherin 23 for hair bundle development. Cadherin 23 was localized to developing stereocilia and proposed as a component of the tip link. We show that, during development of the inner ear, cadherin 23 is initially detected in centrosomes at E14.5, then along the length of emerging stereocilia, and later becomes concentrated at and subsequently disappears from the tops of stereocilia. In mature vestibular hair bundles, cadherin 23 is present along the kinocilium and in the region of stereocilia-kinocilium bonds, a pattern conserved in mammals, chicks, and frogs. Cadherin 23 is also present in Reissner's membrane (RM) throughout development. In homozygous v(6J) mice, a reported null allele, cadherin 23 was absent from stereocilia, but present in kinocilia, RM, and centrosomes. We reconciled these results by identifying two novel isoforms of Cdh23 unaffected in sequence and expression by the v(6J) allele. Our results suggest that Cdh23 participation in stereocilia links may be restricted to developing hair bundles.
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MESH Headings
- Alleles
- Animals
- Blotting, Northern
- Blotting, Western
- Cadherin Related Proteins
- Cadherins/biosynthesis
- Cadherins/chemistry
- Cadherins/metabolism
- Cell Adhesion
- Centrosome/metabolism
- Chick Embryo
- Cilia/metabolism
- DNA, Complementary/metabolism
- Ear, Inner/embryology
- Gene Expression Regulation, Developmental
- Hair Cells, Auditory/embryology
- HeLa Cells
- Homozygote
- Humans
- Intracellular Membranes/metabolism
- Mice
- Mice, Mutant Strains/metabolism
- Microscopy, Fluorescence
- Models, Genetic
- Mutation
- Polymerase Chain Reaction
- Protein Isoforms
- Protein Structure, Tertiary
- Time Factors
- Transfection
- Xenopus
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Affiliation(s)
- Ayala Lagziel
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD 20850, USA
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29
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Siddiqui SA, Cramer KS. Differential expression of Eph receptors and ephrins in the cochlear ganglion and eighth cranial nerve of the chick embryo. J Comp Neurol 2005; 482:309-19. [PMID: 15669077 DOI: 10.1002/cne.20396] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The cochleovestibular ganglion of the chick differentiates at early embryonic stages as VIIIth nerve axons enter the brainstem. The tonotopic organization of the auditory portion of the VIIIth nerve can be discerned at the time axons initially reach their brainstem targets. The mechanisms underlying this early organization are not known. Eph receptor tyrosine kinases and their ligands, the ephrins, have a demonstrated role in guiding axons to topographically appropriate locations in other areas of the nervous system. In order to begin to test whether Eph proteins have a similar role in the auditory system, we investigated the tonotopic expression of several Eph receptors and ephrins in the VIIIth nerve during embryonic ages corresponding to the initial innervation of the auditory brainstem. Expression patterns of EphA4, EphB2, EphB5, ephrin-A2, and ephrin-B1 were evaluated immunohistochemically at embryonic days 4 through 10. Protein expression was observed in the cochlear ganglion and VIIIth nerve axons at these ages. EphB5, ephrin-A2, and ephrin-B1 were expressed throughout the nerve. EphA4 and EphB2 had complementary expression patterns within the nerve, with EphA4 expression higher in the dorsolateral part of the nerve and EphB2 expression higher in the ventromedial part of the nerve. These regions may correspond to auditory and vestibular components, respectively. Moreover, EphA4 expression was higher toward the low-frequency region of both the centrally and peripherally projecting branches of cochlear ganglion cells. Regional variation of Eph protein expression may influence the target selection and topography of developing VIIIth nerve projections.
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Affiliation(s)
- Shazia A Siddiqui
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697, USA
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30
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Frolenkov GI, Belyantseva IA, Friedman TB, Griffith AJ. Genetic insights into the morphogenesis of inner ear hair cells. Nat Rev Genet 2004; 5:489-98. [PMID: 15211351 DOI: 10.1038/nrg1377] [Citation(s) in RCA: 162] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
MESH Headings
- Animals
- Chickens
- Cloning, Molecular
- Cricetinae
- Disease Models, Animal
- Ear, Inner/anatomy & histology
- Ear, Inner/physiology
- Gene Expression Regulation, Developmental
- Hair Cells, Auditory/anatomy & histology
- Hair Cells, Auditory/physiology
- Hearing/genetics
- Hearing Loss/genetics
- Humans
- Mechanotransduction, Cellular
- Mice
- Microscopy, Electron, Scanning
- Microvilli
- Models, Anatomic
- Tissue Adhesions
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Affiliation(s)
- Gregory I Frolenkov
- Section on Gene Structure and Function, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, Maryland 20850, USA
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