1
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You D, Ni W, Huang Y, Zhou Q, Zhang Y, Jiang T, Chen Y, Li W. The proper timing of Atoh1 expression is pivotal for hair cell subtype differentiation and the establishment of inner ear function. Cell Mol Life Sci 2023; 80:349. [PMID: 37930405 PMCID: PMC10628023 DOI: 10.1007/s00018-023-04947-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/30/2023] [Accepted: 09/01/2023] [Indexed: 11/07/2023]
Abstract
Atoh1 overexpression is essential for hair cell (HC) regeneration in the sensory epithelium of mammalian auditory and vestibular organs. However, Atoh1 overexpression alone cannot induce fully mature and functional HCs in the mammalian inner ear. In the current study, we investigated the effect of Atoh1 constitutive overexpression in native HCs by manipulating Atoh1 expression at different developmental stages. We demonstrated that constitutive overexpression of Atoh1 in native vestibular HCs did not affect cell survival but did impair vestibular function by interfering with the subtype differentiation of HCs and hair bundle development. In contrast, Atoh1 overexpression in cochlear HCs impeded their maturation, eventually leading to gradual HC loss in the cochlea and hearing dysfunction. Our study suggests that time-restricted Atoh1 expression is essential for the differentiation and survival of HCs in the inner ear, and this is pivotal for both hearing and vestibular function re-establishment through Atoh1 overexpression-induced HC regeneration strategies.
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Affiliation(s)
- Dan You
- ENT Institute, Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, The Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200031, People's Republic of China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, People's Republic of China
| | - Wenli Ni
- ENT Institute, Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, The Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200031, People's Republic of China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, People's Republic of China
| | - Yikang Huang
- ENT Institute, Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, The Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200031, People's Republic of China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, People's Republic of China
| | - Qin Zhou
- ENT Institute, Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, The Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200031, People's Republic of China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, People's Republic of China
| | - Yanping Zhang
- ENT Institute, Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, The Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200031, People's Republic of China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, People's Republic of China
| | - Tao Jiang
- ENT Institute, Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, The Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200031, People's Republic of China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, People's Republic of China
| | - Yan Chen
- ENT Institute, Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, The Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200031, People's Republic of China.
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, People's Republic of China.
| | - Wenyan Li
- ENT Institute, Department of Otorhinolaryngology, Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, The Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200031, People's Republic of China.
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, 200031, People's Republic of China.
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2
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Yang X, Qi J, Zhang L, Tan F, Huang H, Xu C, Cui Y, Chai R, Wu P. The role of Espin in the stereocilia regeneration and protection in Atoh1-overexpressed cochlear epithelium. Cell Prolif 2023; 56:e13483. [PMID: 37084708 PMCID: PMC10623949 DOI: 10.1111/cpr.13483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 04/05/2023] [Accepted: 04/10/2023] [Indexed: 04/23/2023] Open
Abstract
Hair cells (HCs) in mammals cannot spontaneously regenerate after damage. Atoh1 overexpression can promote HC regeneration in the postnatal cochlea, but the regenerated HCs do not possess the structural and functional characteristics of HCs in situ. The stereocilia on the apical surface of HCs are the first-level structure for sound conduction, and regeneration of functional stereocilia is the key basis for the reproduction of functional HCs. Espin, as an actin bundling protein, plays an important role in the development and structural maintenance of the stereocilia. Here, we found that the upregulation of Espin by AAV-ie was able to induced the aggregation of actin fibres in Atoh1-induced HCs in both cochlear organoids and explants. In addition, we found that persistent Atoh1 overexpression resulted in impaired stereocilia in both endogenous and newly formed HCs. In contrast, the forced expression of Espin in endogenous and regenerative HCs was able to eliminate the stereocilia damage caused by persistent Atoh1 overexpression. Our study shows that the enhanced expression of Espin can optimize the developmental process of stereocilia in Atoh1-induced HCs and can attenuate the damage to native HCs induced by Atoh1 overexpression. These results suggest an effective method to induce the maturation of stereocilia in regenerative HCs and pave the way for functional HC regeneration via supporting cell transdifferentiation.
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Affiliation(s)
- Xuechun Yang
- School of Medicine, South China University of TechnologyGuangzhouChina
- Department of OtolaryngologyGuangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical UniversityGuangzhouChina
| | - Jieyu Qi
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck SurgeryZhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High‐Tech Key Laboratory for Bio‐Medical Research, Southeast UniversityNanjingChina
| | - Liyan Zhang
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck SurgeryZhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High‐Tech Key Laboratory for Bio‐Medical Research, Southeast UniversityNanjingChina
| | - Fangzhi Tan
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck SurgeryZhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High‐Tech Key Laboratory for Bio‐Medical Research, Southeast UniversityNanjingChina
| | - Hongming Huang
- Department of OtolaryngologyGuangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical UniversityGuangzhouChina
| | - Chunlai Xu
- Department of OtolaryngologyHeyuan City People's Hospital, Jinan UniversityGuangzhouChina
| | - Yong Cui
- Department of OtolaryngologyGuangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical UniversityGuangzhouChina
| | - Renjie Chai
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck SurgeryZhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High‐Tech Key Laboratory for Bio‐Medical Research, Southeast UniversityNanjingChina
- Co‐Innovation Center of Neuroregeneration, Nantong UniversityNantongChina
- Department of Otolaryngology Head and Neck SurgerySichuan Provincial People's Hospital, University of Electronic Science and Technology of ChinaChengduChina
- Institute for Stem Cell and RegenerationChinese Academy of ScienceBeijingChina
- Beijing Key Laboratory of Neural Regeneration and RepairCapital Medical UniversityBeijingChina
| | - Peina Wu
- School of Medicine, South China University of TechnologyGuangzhouChina
- Department of OtolaryngologyGuangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical UniversityGuangzhouChina
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3
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Wang Y, Zhang C, Peng W, Du H, Xi Y, Xu Z. RBM24 is required for mouse hair cell development through regulating pre-mRNA alternative splicing and mRNA stability. J Cell Physiol 2023; 238:1095-1110. [PMID: 36947695 DOI: 10.1002/jcp.31003] [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: 12/30/2022] [Revised: 02/28/2023] [Accepted: 03/06/2023] [Indexed: 03/24/2023]
Abstract
As the sensory receptor cells in vertebrate inner ear and lateral lines, hair cells are characterized by the hair bundle that consists of one tubulin-based kinocilium and dozens of actin-based stereocilia on the apical surface of each hair cell. Hair cell development is tightly regulated, and deficits in this process usually lead to hearing loss and/or balance dysfunctions. RNA-binding motif protein 24 (RBM24) is an RNA-binding protein that is specifically expressed in the hair cells in the inner ear. Previously, we showed that RBM24 affects hair cell development in zebrafish by regulating messenger RNA (mRNA) stability. In the present work, we further investigate the role of RBM24 in hearing and balance using conditional knockout mice. Our results show that Rbm24 knockout results in severe hearing and balance deficits. Hair cell development is significantly affected in Rbm24 knockout cochlea, as the hair bundles are poorly developed and eventually degenerated. Hair bundle disorganization is also observed in Rbm24 knockout vestibular hair cells, although to a lesser extent. Consistently, significant hair cell loss is observed in the cochlea but not vestibule. RNAseq analysis identified several genes whose mRNA stability or pre-mRNA alternative splicing is affected by Rbm24 knockout. Among them are Cdh23, Pcdh15, and Myo7a, which have been shown to play important roles in stereocilia development as well as mechano-electrical transduction. Taken together, our present work suggests that RBM24 is required for mouse hair cell development through regulating pre-mRNA alternative splicing as well as mRNA stability.
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Affiliation(s)
- Yanfei Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China
| | - Cuiqiao Zhang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China
| | - Wu Peng
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China
| | - Haibo Du
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China
| | - Yuehui Xi
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China
| | - Zhigang Xu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China
- Shandong Provincial Collaborative Innovation Center of Cell Biology, Shandong Normal University, Jinan, Shandong, China
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4
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Wang J, Zheng J, Wang H, He H, Li S, Zhang Y, Wang Y, Xu X, Wang S. Gene therapy: an emerging therapy for hair cells regeneration in the cochlea. Front Neurosci 2023; 17:1177791. [PMID: 37207182 PMCID: PMC10188948 DOI: 10.3389/fnins.2023.1177791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 04/12/2023] [Indexed: 05/21/2023] Open
Abstract
Sensorineural hearing loss is typically caused by damage to the cochlear hair cells (HCs) due to external stimuli or because of one's genetic factors and the inability to convert sound mechanical energy into nerve impulses. Adult mammalian cochlear HCs cannot regenerate spontaneously; therefore, this type of deafness is usually considered irreversible. Studies on the developmental mechanisms of HC differentiation have revealed that nonsensory cells in the cochlea acquire the ability to differentiate into HCs after the overexpression of specific genes, such as Atoh1, which makes HC regeneration possible. Gene therapy, through in vitro selection and editing of target genes, transforms exogenous gene fragments into target cells and alters the expression of genes in target cells to activate the corresponding differentiation developmental program in target cells. This review summarizes the genes that have been associated with the growth and development of cochlear HCs in recent years and provides an overview of gene therapy approaches in the field of HC regeneration. It concludes with a discussion of the limitations of the current therapeutic approaches to facilitate the early implementation of this therapy in a clinical setting.
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Affiliation(s)
- Jipeng Wang
- Department of Gastrointestinal Surgery, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Jianwei Zheng
- Department of Biliary-Pancreatic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Haiyan Wang
- Department of Otolaryngology-Head and Neck Surgery, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China
| | - Haoying He
- Department of Neurology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China
| | - Shuang Li
- Department of Otolaryngology-Head and Neck Surgery, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China
| | - Ya Zhang
- Department of Otolaryngology-Head and Neck Surgery, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China
| | - You Wang
- Department of Stomatology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China
- *Correspondence: You Wang,
| | - Xiaoxiang Xu
- Department of Otolaryngology-Head and Neck Surgery, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China
- Xiaoxiang Xu,
| | - Shuyi Wang
- Department of Gastrointestinal Surgery, Zhongnan Hospital of Wuhan University, Wuhan, China
- Shuyi Wang,
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5
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Costa A, Powell LM, Malaguti M, Soufi A, Lowell S, Jarman AP. Repurposing the lineage-determining transcription factor Atoh1 without redistributing its genomic binding sites. Front Cell Dev Biol 2022; 10:1016367. [PMID: 36420143 PMCID: PMC9676683 DOI: 10.3389/fcell.2022.1016367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 10/17/2022] [Indexed: 11/09/2022] Open
Abstract
Although the lineage-determining ability of transcription factors is often modulated according to cellular context, the mechanisms by which such switching occurs are not well known. Using a transcriptional programming model, we found that Atoh1 is repurposed from a neuronal to an inner ear hair cell (HC) determinant by the combined activities of Gfi1 and Pou4f3. In this process, Atoh1 maintains its regulation of neuronal genes but gains ability to regulate HC genes. Pou4f3 enables Atoh1 access to genomic locations controlling the expression of sensory (including HC) genes, but Atoh1 + Pou4f3 are not sufficient for HC differentiation. Gfi1 is key to the Atoh1-induced lineage switch, but surprisingly does not alter Atoh1's binding profile. Gfi1 acts in two divergent ways. It represses the induction by Atoh1 of genes that antagonise HC differentiation, a function in keeping with its well-known repressor role in haematopoiesis. Remarkably, we find that Gfi1 also acts as a co-activator: it binds directly to Atoh1 at existing target genes to enhance its activity. These findings highlight the diversity of mechanisms by which one TF can redirect the activity of another to enable combinatorial control of cell identity.
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Affiliation(s)
- Aida Costa
- Centre for Discovery Brain Sciences, Edinburgh Medical School, University of Edinburgh, Edinburgh, United Kingdom
- MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Lynn M. Powell
- Centre for Discovery Brain Sciences, Edinburgh Medical School, University of Edinburgh, Edinburgh, United Kingdom
| | - Mattias Malaguti
- MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Abdenour Soufi
- MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Sally Lowell
- MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew P. Jarman
- Centre for Discovery Brain Sciences, Edinburgh Medical School, University of Edinburgh, Edinburgh, United Kingdom
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Lu X, Yu H, Ma J, Wang K, Guo L, Zhang Y, Li B, Zhao Z, Li H, Sun S. Loss of Mst1/2 activity promotes non-mitotic hair cell generation in the neonatal organ of Corti. NPJ Regen Med 2022; 7:64. [PMID: 36280668 PMCID: PMC9592590 DOI: 10.1038/s41536-022-00261-4] [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: 01/17/2022] [Accepted: 10/10/2022] [Indexed: 11/09/2022] Open
Abstract
Mammalian sensory hair cells (HCs) have limited capacity for regeneration, which leads to permanent hearing loss after HC death. Here, we used in vitro RNA-sequencing to show that the Hippo signaling pathway is involved in HC damage and self-repair processes. Turning off Hippo signaling through Mst1/2 inhibition or Yap overexpression induces YAP nuclear accumulation, especially in supporting cells, which induces supernumerary HC production and HC regeneration after injury. Mechanistically, these effects of Hippo signaling work synergistically with the Notch pathway. Importantly, the supernumerary HCs not only express HC markers, but also have cilia structures that are able to form neural connections to auditory regions in vivo. Taken together, regulating Hippo suggests new strategies for promoting cochlear supporting cell proliferation, HC regeneration, and reconnection with neurons in mammals.
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Affiliation(s)
- Xiaoling Lu
- grid.8547.e0000 0001 0125 2443ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, NHC Key Laboratory of Hearing Medicine (Fudan University), Fudan University, 200031 Shanghai, P. R. China
| | - Huiqian Yu
- grid.8547.e0000 0001 0125 2443ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, NHC Key Laboratory of Hearing Medicine (Fudan University), Fudan University, 200031 Shanghai, P. R. China
| | - Jiaoyao Ma
- grid.8547.e0000 0001 0125 2443ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, NHC Key Laboratory of Hearing Medicine (Fudan University), Fudan University, 200031 Shanghai, P. R. China
| | - Kunkun Wang
- grid.8547.e0000 0001 0125 2443ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, NHC Key Laboratory of Hearing Medicine (Fudan University), Fudan University, 200031 Shanghai, P. R. China
| | - Luo Guo
- grid.8547.e0000 0001 0125 2443ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, NHC Key Laboratory of Hearing Medicine (Fudan University), Fudan University, 200031 Shanghai, P. R. China
| | - Yanping Zhang
- grid.8547.e0000 0001 0125 2443ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, NHC Key Laboratory of Hearing Medicine (Fudan University), Fudan University, 200031 Shanghai, P. R. China
| | - Boan Li
- grid.12955.3a0000 0001 2264 7233Xiamen University School of Life Sciences, 361100 Xiamen, P. R. China
| | - Zehang Zhao
- grid.12955.3a0000 0001 2264 7233Xiamen University School of Life Sciences, 361100 Xiamen, P. R. China
| | - Huawei Li
- grid.8547.e0000 0001 0125 2443ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, NHC Key Laboratory of Hearing Medicine (Fudan University), Fudan University, 200031 Shanghai, P. R. China ,grid.8547.e0000 0001 0125 2443Institutes of Biomedical Sciences, Fudan University, 200032 Shanghai, P. R. China ,grid.8547.e0000 0001 0125 2443The Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, 200032 Shanghai, China
| | - Shan Sun
- grid.8547.e0000 0001 0125 2443ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, NHC Key Laboratory of Hearing Medicine (Fudan University), Fudan University, 200031 Shanghai, P. R. China
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7
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O’Donnell J, Zheng J. Vestibular Hair Cells Require CAMSAP3, a Microtubule Minus-End Regulator, for Formation of Normal Kinocilia. Front Cell Neurosci 2022; 16:876805. [PMID: 35783105 PMCID: PMC9247359 DOI: 10.3389/fncel.2022.876805] [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: 02/15/2022] [Accepted: 05/30/2022] [Indexed: 11/29/2022] Open
Abstract
Kinocilia are exceptionally long primary sensory cilia located on vestibular hair cells, which are essential for transmitting key signals that contribute to mammalian balance and overall vestibular system function. Kinocilia have a “9+2” microtubule (MT) configuration with nine doublet MTs surrounding two central singlet MTs. This is uncommon as most mammalian primary sensory cilia have a “9+0” configuration, in which the central MT pair is absent. It has yet to be determined what the function of the central MT pair is in kinocilia. Calmodulin-regulated spectrin-associated protein 3 (CAMSAP3) regulates the minus end of MTs and is essential for forming the central MT pair in motile cilia, which have the “9+2” configuration. To explore the role of the central MT pair in kinocilia, we created a conditional knockout model (cKO), Camsap3-cKO, which intended to eliminate CAMSAP3 in limited organs including the inner ear, olfactory bulb, and kidneys. Immunofluorescent staining of vestibular organs demonstrated that CAMSAP3 proteins were significantly reduced in Camsap3-cKO mice and that aged Camsap3-cKO mice had significantly shorter kinocilia than their wildtype littermates. Transmission electron microscopy showed that aged Camsap3-cKO mice were in fact missing that the central MT pair in kinocilia more often than their wildtype counterparts. In the examination of behavior, wildtype and Camsap3-cKO mice performed equally well on a swim assessment, right-reflex test, and evaluation of balance on a rotarod. However, Camsap3-cKO mice showed slightly altered gaits including reduced maximal rate of change of paw area and a smaller paw area in contact with the surface. Although Camsap3-cKO mice had no differences in olfaction from their wildtype counterparts, Camsap3-cKO mice did have kidney dysfunction that deteriorated their health. Thus, CAMSAP3 is important for establishing and/or maintaining the normal structure of kinocilia and kidney function but is not essential for normal olfaction. Our data supports our hypothesis that CAMSAP3 is critical for construction of the central MT pair in kinocilia, and that the central MT pair may be important for building long and stable axonemes in these kinocilia. Whether shorter kinocilia might lead to abnormal vestibular function and altered gaits in older Camsap3-cKO mice requires further investigation.
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Affiliation(s)
- Josephine O’Donnell
- Department of Otolaryngology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Jing Zheng
- Department of Otolaryngology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
- Knowles Hearing Center, Northwestern University, Evanston, IL, United States
- *Correspondence: Jing Zheng,
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8
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Mackowetzky K, Dicipulo R, Fox SC, Philibert DA, Todesco H, Doshi JD, Kawakami K, Tierney K, Waskiewicz AJ. Retinoic acid signaling regulates late stages of semicircular canal morphogenesis and otolith maintenance in the zebrafish inner ear. Dev Dyn 2022; 251:1798-1815. [PMID: 35710880 DOI: 10.1002/dvdy.510] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND The vitamin A derivative all-trans retinoic acid (RA) regulates early stages of inner ear development. As the early disruption of the RA pathway results in profound mispatterning of the developing inner ear, this confounds analyses of specific roles in later stages. Therefore, we used the temporal-specific exposure of all-trans RA or diethylaminobenzaldehyde to evaluate RA functions in late otic development. RESULTS Perturbing late RA signaling causes behavioral defects analogous to those expected in larvae suffering from vestibular dysfunction. These larvae also demonstrate malformations of the semi-circular canals, as visualized through (a) use of the transgenic strain nkhspdmc12a, a fluorescent reporter expressed in otic epithelium; and (b) injection of the fluorescent lipophilic dye DiI. We also noted the altered expression of genes encoding ECM proteins or modifying enzymes. Other malformations of the inner ear observed in our work include the loss or reduced size of the utricular and saccular otoliths, suggesting a role for RA in otolith maintenance. CONCLUSION Our work has identified a previously undescribed late phase of RA activity in otic development, demonstrating that vestibular defects observed in human patients in relation to perturbed RA signaling are not solely due to its early disruption in otic development.
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Affiliation(s)
- Kacey Mackowetzky
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Renée Dicipulo
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Sabrina C Fox
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Women & Children's Health Research Institute, Edmonton, Alberta, Canada
| | - Danielle A Philibert
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Hayley Todesco
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Jainil D Doshi
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Koichi Kawakami
- Laboratory of Molecular and Developmental Biology, National Institute of Genetics, Shizuoka, Japan
| | - Keith Tierney
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,School of Public Health, University of Alberta, Edmonton, Alberta, Canada
| | - Andrew J Waskiewicz
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Women & Children's Health Research Institute, Edmonton, Alberta, Canada
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9
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Li S, Fan T, Li C, Wang Y, Li J, Liu Z. Fate-mapping analysis of cochlear cells expressing Atoh1 mRNA via a new Atoh1 3*HA-P2A-Cre knockin mouse strain. Dev Dyn 2022; 251:1156-1174. [PMID: 35038200 DOI: 10.1002/dvdy.453] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 01/06/2022] [Accepted: 01/07/2022] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Atoh1 is recognized to be essential for cochlear hair cell (HC) development. However, Atoh1 temporal and spatial expression patterns remain widely debated. Here, we aimed to obtain evidence to resolve the controversies regarding Atoh1 expression by generating a new knockin mouse strain: Atoh13*HA-P2A-Cre . RESULTS Fate-mapping analysis of Atoh13*HA-P2A-Cre/+ ; Rosa26-CAG-LSL-tdTomato (Ai9)/+ mice enabled us to concurrently characterize the temporal expression of Atoh1 protein (through HA-tag immunostaining) and visualize the cells expressing Atoh1 mRNA (as tdTomato+ cells). Our findings show that whereas Atoh1 mRNA expression is rapidly turned on in early cochlear progenitors, Atoh1 protein is only detected in differentiating HCs or progenitors just committed to the HC fate. Cre activity is also stronger in Atoh13*HA-P2A-Cre/+ than in previous mouse models, because almost all cochlear HCs and nearby supporting cells here are tdTomato+. Furthermore, tdTomato, but not HA, is expressed in middle and apical spiral ganglion neurons. CONCLUSION Collectively, our findings indicate that Atoh13*HA-P2A-Cre can serve as a powerful genetic model in the developmental biology field. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Shuting Li
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
| | - Ting Fan
- ENT Institute and Otorhinolaryngology Department, Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China.,Key Laboratory of Hearing Medicine, National Health and Family Planning Commission (NHFPC), Shanghai, China
| | - Chao Li
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
| | - Yunfeng Wang
- ENT Institute and Otorhinolaryngology Department, Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China.,Key Laboratory of Hearing Medicine, National Health and Family Planning Commission (NHFPC), Shanghai, China
| | - Jian Li
- Clinical Laboratory Center, Children's Hospital of Fudan University, Shanghai, China
| | - Zhiyong Liu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai, China
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10
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Mackowetzky K, Yoon KH, Mackowetzky EJ, Waskiewicz AJ. Development and evolution of the vestibular apparatuses of the inner ear. J Anat 2021; 239:801-828. [PMID: 34047378 PMCID: PMC8450482 DOI: 10.1111/joa.13459] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 04/07/2021] [Accepted: 05/06/2021] [Indexed: 12/16/2022] Open
Abstract
The vertebrate inner ear is a labyrinthine sensory organ responsible for perceiving sound and body motion. While a great deal of research has been invested in understanding the auditory system, a growing body of work has begun to delineate the complex developmental program behind the apparatuses of the inner ear involved with vestibular function. These animal studies have helped identify genes involved in inner ear development and model syndromes known to include vestibular dysfunction, paving the way for generating treatments for people suffering from these disorders. This review will provide an overview of known inner ear anatomy and function and summarize the exciting discoveries behind inner ear development and the evolution of its vestibular apparatuses.
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Affiliation(s)
- Kacey Mackowetzky
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - Kevin H. Yoon
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | | | - Andrew J. Waskiewicz
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
- Women & Children’s Health Research InstituteUniversity of AlbertaEdmontonAlbertaCanada
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11
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Liu Z, Bai X, Wan P, Mo F, Chen G, Zhang J, Gao J. Targeted Deletion of Loxl3 by Col2a1-Cre Leads to Progressive Hearing Loss. Front Cell Dev Biol 2021; 9:683495. [PMID: 34150778 PMCID: PMC8212933 DOI: 10.3389/fcell.2021.683495] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 05/11/2021] [Indexed: 12/20/2022] Open
Abstract
Collagens are major constituents of the extracellular matrix (ECM) that play an essential role in the structure of the inner ear and provide elasticity and rigidity when the signals of sound are received and transformed into electrical signals. LOXL3 is a member of the lysyl oxidase (LOX) family that are copper-dependent amine oxidases, generating covalent cross-links to stabilize polymeric elastin and collagen fibers in the ECM. Biallelic missense variant of LOXL3 was found in Stickler syndrome with mild conductive hearing loss. However, available information regarding the specific roles of LOXL3 in auditory function is limited. In this study, we showed that the Col2a1-Cre-mediated ablation of Loxl3 in the inner ear can cause progressive hearing loss, degeneration of hair cells and secondary degeneration of spiral ganglion neurons. The abnormal distribution of type II collagen in the spiral ligament and increased inflammatory responses were also found in Col2a1–Loxl3–/– mice. Amino oxidase activity exerts an effect on collagen; thus, Loxl3 deficiency was expected to result in the instability of collagen in the spiral ligament and the basilar membrane, which may interfere with the mechanical properties of the organ of Corti and induce the inflammatory responses that are responsible for the hearing loss. Overall, our findings suggest that Loxl3 may play an essential role in maintaining hearing function.
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Affiliation(s)
- Ziyi Liu
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China
| | - Xinfeng Bai
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China
| | - Peifeng Wan
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China
| | - Fan Mo
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China
| | - Ge Chen
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China
| | - Jian Zhang
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China
| | - Jiangang Gao
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan, China
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12
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Warnecke A, Giesemann A. Embryology, Malformations, and Rare Diseases of the Cochlea. Laryngorhinootologie 2021; 100:S1-S43. [PMID: 34352899 PMCID: PMC8354575 DOI: 10.1055/a-1349-3824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Despite the low overall prevalence of individual rare diseases, cochlear
dysfunction leading to hearing loss represents a symptom in a large
proportion. The aim of this work was to provide a clear overview of rare
cochlear diseases, taking into account the embryonic development of the
cochlea and the systematic presentation of the different disorders. Although
rapid biotechnological and bioinformatic advances may facilitate the
diagnosis of a rare disease, an interdisciplinary exchange is often required
to raise the suspicion of a rare disease. It is important to recognize that
the phenotype of rare inner ear diseases can vary greatly not only in
non-syndromic but also in syndromic hearing disorders. Finally, it becomes
clear that the phenotype of the individual rare diseases cannot be
determined exclusively by classical genetics even in monogenetic
disorders.
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Affiliation(s)
- Athanasia Warnecke
- Klinik für Hals-, Nasen- und Ohrenheilkunde, Medizinische Hochschule Hannover, Carl-Neuberg-Straße 1, 30625 Hannover.,Deutsche Forschungsgemeinschaft Exzellenzcluster"Hearing4all" - EXC 2177/1 - Project ID 390895286
| | - Anja Giesemann
- Institut für Neuroradiologie, Medizinische Hochschule Hannover, Carl-Neuberg-Straße 1, 30625 Hannover
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13
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Elliott KL, Pavlínková G, Chizhikov VV, Yamoah EN, Fritzsch B. Development in the Mammalian Auditory System Depends on Transcription Factors. Int J Mol Sci 2021; 22:ijms22084189. [PMID: 33919542 PMCID: PMC8074135 DOI: 10.3390/ijms22084189] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 04/15/2021] [Accepted: 04/16/2021] [Indexed: 12/16/2022] Open
Abstract
We review the molecular basis of several transcription factors (Eya1, Sox2), including the three related genes coding basic helix–loop–helix (bHLH; see abbreviations) proteins (Neurog1, Neurod1, Atoh1) during the development of spiral ganglia, cochlear nuclei, and cochlear hair cells. Neuronal development requires Neurog1, followed by its downstream target Neurod1, to cross-regulate Atoh1 expression. In contrast, hair cells and cochlear nuclei critically depend on Atoh1 and require Neurod1 expression for interactions with Atoh1. Upregulation of Atoh1 following Neurod1 loss changes some vestibular neurons’ fate into “hair cells”, highlighting the significant interplay between the bHLH genes. Further work showed that replacing Atoh1 by Neurog1 rescues some hair cells from complete absence observed in Atoh1 null mutants, suggesting that bHLH genes can partially replace one another. The inhibition of Atoh1 by Neurod1 is essential for proper neuronal cell fate, and in the absence of Neurod1, Atoh1 is upregulated, resulting in the formation of “intraganglionic” HCs. Additional genes, such as Eya1/Six1, Sox2, Pax2, Gata3, Fgfr2b, Foxg1, and Lmx1a/b, play a role in the auditory system. Finally, both Lmx1a and Lmx1b genes are essential for the cochlear organ of Corti, spiral ganglion neuron, and cochlear nuclei formation. We integrate the mammalian auditory system development to provide comprehensive insights beyond the limited perception driven by singular investigations of cochlear neurons, cochlear hair cells, and cochlear nuclei. A detailed analysis of gene expression is needed to understand better how upstream regulators facilitate gene interactions and mammalian auditory system development.
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Affiliation(s)
- Karen L. Elliott
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA;
| | - Gabriela Pavlínková
- Institute of Biotechnology of the Czech Academy of Sciences, 25250 Vestec, Czechia;
| | - Victor V. Chizhikov
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN 38163, USA;
| | - Ebenezer N. Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV 89557, USA;
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA;
- Correspondence:
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14
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Steevens AR, Griesbach MW, You Y, Dutton JR, Low WC, Santi PA. Generation of inner ear sensory neurons using blastocyst complementation in a Neurog1 +/--deficient mouse. Stem Cell Res Ther 2021; 12:122. [PMID: 33579352 PMCID: PMC7881691 DOI: 10.1186/s13287-021-02184-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 01/24/2021] [Indexed: 11/10/2022] Open
Abstract
This research is the first to produce induced pluripotent stem cell-derived inner ear sensory neurons in the Neurog1+/− heterozygote mouse using blastocyst complementation. Additionally, this approach corrected non-sensory deficits associated with Neurog1 heterozygosity, indicating that complementation is specific to endogenous Neurog1 function. This work validates the use of blastocyst complementation as a tool to create novel insight into the function of developmental genes and highlights blastocyst complementation as a potential platform for generating chimeric inner ear cell types that can be transplanted into damaged inner ears to improve hearing.
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Affiliation(s)
- Aleta R Steevens
- Department of Ophthalmology, University of Minnesota, Minneapolis, MN, USA. .,Department of Neurosurgery, University of Minnesota, Minneapolis, MN, USA. .,Stem Cell Institute, University of Minnesota, Minneapolis, MN, USA.
| | | | - Yun You
- Mouse Genetics Laboratory, University of Minnesota, Minneapolis, MN, USA
| | - James R Dutton
- Stem Cell Institute, University of Minnesota, Minneapolis, MN, USA
| | - Walter C Low
- Department of Neurosurgery, University of Minnesota, Minneapolis, MN, USA.,Stem Cell Institute, University of Minnesota, Minneapolis, MN, USA
| | - Peter A Santi
- Stem Cell Institute, University of Minnesota, Minneapolis, MN, USA.,Department of Otolaryngology, University of Minnesota, Minneapolis, MN, USA
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15
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Jahan I, Kersigo J, Elliott KL, Fritzsch B. Smoothened overexpression causes trochlear motoneurons to reroute and innervate ipsilateral eyes. Cell Tissue Res 2021; 384:59-72. [PMID: 33409653 DOI: 10.1007/s00441-020-03352-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 11/16/2020] [Indexed: 12/22/2022]
Abstract
The trochlear projection is unique among the cranial nerves in that it exits the midbrain dorsally to innervate the contralateral superior oblique muscle in all vertebrates. Trochlear as well as oculomotor motoneurons uniquely depend upon Phox2a and Wnt1, both of which are downstream of Lmx1b, though why trochlear motoneurons display such unusual projections is not fully known. We used Pax2-cre to drive expression of ectopically activated Smoothened (SmoM2) dorsally in the midbrain and anterior hindbrain. We documented the expansion of oculomotor and trochlear motoneurons using Phox2a as a specific marker at E9.5. We show that the initial expansion follows a demise of these neurons by E14.5. Furthermore, SmoM2 expression leads to a ventral exit and ipsilateral projection of trochlear motoneurons. We compare that data with Unc5c mutants that shows a variable ipsilateral number of trochlear fibers that exit dorsal. Our data suggest that Shh signaling is involved in trochlear motoneuron projections and that the deflected trochlear projections after SmoM2 expression is likely due to the dorsal expression of Gli1, which impedes the normal dorsal trajectory of these neurons.
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Affiliation(s)
- Israt Jahan
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA
| | - Jennifer Kersigo
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA
| | - Karen L Elliott
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA. .,Department of Otolaryngology, University of Iowa, Iowa City, IA, 52242, USA.
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16
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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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17
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He L, Guo JY, Liu K, Wang GP, Gong SS. Research progress on flat epithelium of the inner ear. Physiol Res 2020; 69:775-785. [PMID: 32901490 DOI: 10.33549/physiolres.934447] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Sensorineural hearing loss and vertigo, resulting from lesions in the sensory epithelium of the inner ear, have a high incidence worldwide. The sensory epithelium of the inner ear may exhibit extreme degeneration and is transformed to flat epithelium (FE) in humans and mice with profound sensorineural hearing loss and/or vertigo. Various factors, including ototoxic drugs, noise exposure, aging, and genetic defects, can induce FE. Both hair cells and supporting cells are severely damaged in FE, and the normal cytoarchitecture of the sensory epithelium is replaced by a monolayer of very thin, flat cells of irregular contour. The pathophysiologic mechanism of FE is unclear but involves robust cell division. The cellular origin of flat cells in FE is heterogeneous; they may be transformed from supporting cells that have lost some features of supporting cells (dedifferentiation) or may have migrated from the flanking region. The epithelial-mesenchymal transition may play an important role in this process. The treatment of FE is challenging given the severe degeneration and loss of both hair cells and supporting cells. Cochlear implant or vestibular prosthesis implantation, gene therapy, and stem cell therapy show promise for the treatment of FE, although many challenges remain to be overcome.
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Affiliation(s)
- L He
- Department of Otolaryngology-Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China. ,
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18
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Brownstein Z, Gulsuner S, Walsh T, Martins FTA, Taiber S, Isakov O, Lee MK, Bordeynik-Cohen M, Birkan M, Chang W, Casadei S, Danial-Farran N, Abu-Rayyan A, Carlson R, Kamal L, Arnþórsson ÁÖ, Sokolov M, Gilony D, Lipschitz N, Frydman M, Davidov B, Macarov M, Sagi M, Vinkler C, Poran H, Sharony R, Samara N, Zvi N, Baris-Feldman H, Singer A, Handzel O, Hertzano R, Ali-Naffaa D, Ruhrman-Shahar N, Madgar O, Sofrin E, Peleg A, Khayat M, Shohat M, Basel-Salmon L, Pras E, Lev D, Wolf M, Steingrimsson E, Shomron N, Kelley MW, Kanaan M, Allon-Shalev S, King MC, Avraham KB. Spectrum of genes for inherited hearing loss in the Israeli Jewish population, including the novel human deafness gene ATOH1. Clin Genet 2020; 98:353-364. [PMID: 33111345 PMCID: PMC8045518 DOI: 10.1111/cge.13817] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 07/13/2020] [Accepted: 07/15/2020] [Indexed: 12/26/2022]
Abstract
Mutations in more than 150 genes are responsible for inherited hearing loss, with thousands of different, severe causal alleles that vary among populations. The Israeli Jewish population includes communities of diverse geographic origins, revealing a wide range of deafness-associated variants and enabling clinical characterization of the associated phenotypes. Our goal was to identify the genetic causes of inherited hearing loss in this population, and to determine relationships among genotype, phenotype, and ethnicity. Genomic DNA samples from informative relatives of 88 multiplex families, all of self-identified Jewish ancestry, with either non-syndromic or syndromic hearing loss, were sequenced for known and candidate deafness genes using the HEar-Seq gene panel. The genetic causes of hearing loss were identified for 60% of the families. One gene was encountered for the first time in human hearing loss: ATOH1 (Atonal), a basic helix-loop-helix transcription factor responsible for autosomal dominant progressive hearing loss in a five-generation family. Our results show that genomic sequencing with a gene panel dedicated to hearing loss is effective for genetic diagnoses in a diverse population. Comprehensive sequencing enables well-informed genetic counseling and clinical management by medical geneticists, otolaryngologists, audiologists, and speech therapists and can be integrated into newborn screening for deafness.
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Affiliation(s)
- Zippora Brownstein
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Suleyman Gulsuner
- Departments of Genome Sciences and Medicine, University of Washington, Seattle, WA, USA
| | - Tom Walsh
- Departments of Genome Sciences and Medicine, University of Washington, Seattle, WA, USA
| | - Fábio Tadeu Arrojo Martins
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Shahar Taiber
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Ofer Isakov
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ming K. Lee
- Departments of Genome Sciences and Medicine, University of Washington, Seattle, WA, USA
| | - Mor Bordeynik-Cohen
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Maria Birkan
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Raphael Recanati Genetic Institute, Rabin Medical Center–Beilinson Hospital, Tel Aviv University Felsenstein Medical Research Center, Petach Tikva, Israel
| | - Weise Chang
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communications Disorders, NIH, Bethesda, MD, USA
| | - Silvia Casadei
- Departments of Genome Sciences and Medicine, University of Washington, Seattle, WA, USA
| | - Nada Danial-Farran
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Genetics Institute, Ha'Emek Medical Center, Afula, Israel
- Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Amal Abu-Rayyan
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Department of Biological Sciences, Bethlehem University, Bethlehem, Palestine
| | - Ryan Carlson
- Departments of Genome Sciences and Medicine, University of Washington, Seattle, WA, USA
| | - Lara Kamal
- Department of Biological Sciences, Bethlehem University, Bethlehem, Palestine
| | - Ásgeir Örn Arnþórsson
- Department of Biochemistry and Molecular Biology, BioMedical Center, Faculty of Medicine, University of Iceland, Reykjavik, Iceland
| | - Meirav Sokolov
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Department of Otolaryngology - Head and Neck Surgery, Schneider Children's Medical Center, Petach Tikva, Israel
| | - Dror Gilony
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Department of Otolaryngology - Head and Neck Surgery, Schneider Children's Medical Center, Petach Tikva, Israel
| | - Noga Lipschitz
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Department of Otolaryngology - Head and Neck Surgery, Sheba Medical Center, Tel Hashomer, Israel
| | - Moshe Frydman
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Institute of Human Genetics, Sheba Medical Center, Tel Hashomer, Israel
| | - Bella Davidov
- Raphael Recanati Genetic Institute, Rabin Medical Center–Beilinson Hospital, Tel Aviv University Felsenstein Medical Research Center, Petach Tikva, Israel
| | - Michal Macarov
- Department of Human Genetics and Metabolic Diseases, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Michal Sagi
- Department of Human Genetics and Metabolic Diseases, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Chana Vinkler
- Institute of Medical Genetics, Wolfson Medical Center, Holon, Israel
| | - Hana Poran
- Institute of Human Genetics, Sheba Medical Center, Tel Hashomer, Israel
| | - Reuven Sharony
- Genetics Institute, Meir Medical Center, Kfar Saba and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | | - Na’ama Zvi
- Department of Human Genetics and Metabolic Diseases, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | | | - Amihood Singer
- Community Genetics Department, Public Health Services, Ministry of Health, Ramat Gan, Israel
| | - Ophir Handzel
- Department of Otolaryngology Head and Neck Surgery and Maxillofacial Surgery, Tel-Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Ronna Hertzano
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Doaa Ali-Naffaa
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Human Genetics Institute, Lady Davis Carmel Medical Center, Haifa, Israel
| | - Noa Ruhrman-Shahar
- Raphael Recanati Genetic Institute, Rabin Medical Center–Beilinson Hospital, Tel Aviv University Felsenstein Medical Research Center, Petach Tikva, Israel
| | - Ory Madgar
- Department of Otolaryngology - Head and Neck Surgery, Sheba Medical Center, Tel Hashomer, Israel
| | - Efrat Sofrin
- Raphael Recanati Genetic Institute, Rabin Medical Center–Beilinson Hospital, Tel Aviv University Felsenstein Medical Research Center, Petach Tikva, Israel
| | - Amir Peleg
- Human Genetics Institute, Lady Davis Carmel Medical Center, Haifa, Israel
| | - Morad Khayat
- Genetics Institute, Ha'Emek Medical Center, Afula, Israel
| | - Mordechai Shohat
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Sheba Cancer Research Center, Sheba Medical Center, Tel Hashomer, Israel
- Institute of Medical Genetics, Maccabi HMO, Rehovot, Israel
| | - Lina Basel-Salmon
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Raphael Recanati Genetic Institute, Rabin Medical Center–Beilinson Hospital, Tel Aviv University Felsenstein Medical Research Center, Petach Tikva, Israel
| | - Elon Pras
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Institute of Human Genetics, Sheba Medical Center, Tel Hashomer, Israel
| | - Dorit Lev
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Institute of Medical Genetics, Wolfson Medical Center, Holon, Israel
| | - Michael Wolf
- Department of Otolaryngology - Head and Neck Surgery, Sheba Medical Center, Tel Hashomer, Israel
| | - Eirikur Steingrimsson
- Department of Biochemistry and Molecular Biology, BioMedical Center, Faculty of Medicine, University of Iceland, Reykjavik, Iceland
| | - Noam Shomron
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Matthew W. Kelley
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communications Disorders, NIH, Bethesda, MD, USA
| | - Moien Kanaan
- Department of Biological Sciences, Bethlehem University, Bethlehem, Palestine
| | - Stavit Allon-Shalev
- Genetics Institute, Ha'Emek Medical Center, Afula, Israel
- Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Mary-Claire King
- Departments of Genome Sciences and Medicine, University of Washington, Seattle, WA, USA
| | - Karen B. Avraham
- Department of Human Molecular Genetics & Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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Combined Atoh1 and Neurod1 Deletion Reveals Autonomous Growth of Auditory Nerve Fibers. Mol Neurobiol 2020; 57:5307-5323. [PMID: 32880858 DOI: 10.1007/s12035-020-02092-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Accepted: 08/24/2020] [Indexed: 12/24/2022]
Abstract
Ear development requires the transcription factors ATOH1 for hair cell differentiation and NEUROD1 for sensory neuron development. In addition, NEUROD1 negatively regulates Atoh1 gene expression. As we previously showed that deletion of the Neurod1 gene in the cochlea results in axon guidance defects and excessive peripheral innervation of the sensory epithelium, we hypothesized that some of the innervation defects may be a result of abnormalities in NEUROD1 and ATOH1 interactions. To characterize the interdependency of ATOH1 and NEUROD1 in inner ear development, we generated a new Atoh1/Neurod1 double null conditional deletion mutant. Through careful comparison of the effects of single Atoh1 or Neurod1 gene deletion with combined double Atoh1 and Neurod1 deletion, we demonstrate that NEUROD1-ATOH1 interactions are not important for the Neurod1 null innervation phenotype. We report that neurons lacking Neurod1 can innervate the flat epithelium without any sensory hair cells or supporting cells left after Atoh1 deletion, indicating that neurons with Neurod1 deletion do not require the presence of hair cells for axon growth. Moreover, transcriptome analysis identified genes encoding axon guidance and neurite growth molecules that are dysregulated in the Neurod1 deletion mutant. Taken together, we demonstrate that much of the projections of NEUROD1-deprived inner ear sensory neurons are regulated cell-autonomously.
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20
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Zhang S, Qiang R, Dong Y, Zhang Y, Chen Y, Zhou H, Gao X, Chai R. Hair cell regeneration from inner ear progenitors in the mammalian cochlea. AMERICAN JOURNAL OF STEM CELLS 2020; 9:25-35. [PMID: 32699655 PMCID: PMC7364385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 06/10/2020] [Indexed: 06/11/2023]
Abstract
Cochlear hair cells (HCs) are the mechanoreceptors of the auditory system, and because these cells cannot be spontaneously regenerated in adult mammals, hearing loss due to HC damage is permanent. However, cochleae of neonatal mice harbor some progenitor cells that retain limited ability to give rise to new HCs in vivo. Here we review the regulatory factors, signaling pathways, and epigenetic factors that have been reported to play roles in HC regeneration in the neonatal mammalian cochlea.
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Affiliation(s)
- Shasha Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing 210096, China
| | - Ruiying Qiang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing 210096, China
| | - Ying Dong
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing 210096, China
| | - Yuan Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing 210096, China
| | - Yin Chen
- Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory)Nanjing 210008, China
| | - Han Zhou
- Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory)Nanjing 210008, China
| | - Xia Gao
- Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory)Nanjing 210008, China
| | - Renjie Chai
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing 210096, China
- Co-Innovation Center of Neuroregeneration, Nantong UniversityNantong 226001, China
- Institute for Stem Cell and Regeneration, Chinese Academy of ScienceBeijing, China
- Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast UniversityNanjing 211189, China
- Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory)Nanjing 210008, China
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21
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He L, Guo JY, Qu TF, Wei W, Liu K, Peng Z, Wang GP, Gong SS. Cellular origin and response of flat epithelium in the vestibular end organs of mice to Atoh1 overexpression. Hear Res 2020; 391:107953. [DOI: 10.1016/j.heares.2020.107953] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 03/02/2020] [Accepted: 03/17/2020] [Indexed: 02/01/2023]
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22
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Using Sox2 to alleviate the hallmarks of age-related hearing loss. Ageing Res Rev 2020; 59:101042. [PMID: 32173536 DOI: 10.1016/j.arr.2020.101042] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 03/04/2020] [Accepted: 03/05/2020] [Indexed: 02/07/2023]
Abstract
Age-related hearing loss (ARHL) is the most prevalent sensory deficit. ARHL reduces the quality of life of the growing population, setting seniors up for the enhanced mental decline. The size of the needy population, the structural deficit, and a likely research strategy for effective treatment of chronic neurosensory hearing in the elderly are needed. Although there has been profound advancement in auditory regenerative research, there remain multiple challenges to restore hearing loss. Thus, additional investigations are required, using novel tools. We propose how the (1) flat epithelium, remaining after the organ of Corti has deteriorated, can be converted to the repaired-sensory epithelium, using Sox2. This will include (2) developing an artificial gene regulatory network transmitted by (3) large viral vectors to the flat epithelium to stimulate remnants of the organ of Corti to restore hair cells. We hope to unite with our proposal toward the common goal, eventually restoring a functional human hearing organ by transforming the flat epithelial cells left after the organ of Corti loss.
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23
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Zhang S, Zhang Y, Dong Y, Guo L, Zhang Z, Shao B, Qi J, Zhou H, Zhu W, Yan X, Hong G, Zhang L, Zhang X, Tang M, Zhao C, Gao X, Chai R. Knockdown of Foxg1 in supporting cells increases the trans-differentiation of supporting cells into hair cells in the neonatal mouse cochlea. Cell Mol Life Sci 2020; 77:1401-1419. [PMID: 31485717 PMCID: PMC7113235 DOI: 10.1007/s00018-019-03291-2] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 08/08/2019] [Accepted: 08/28/2019] [Indexed: 12/17/2022]
Abstract
Foxg1 is one of the forkhead box genes that are involved in morphogenesis, cell fate determination, and proliferation, and Foxg1 was previously reported to be required for morphogenesis of the mammalian inner ear. However, Foxg1 knock-out mice die at birth, and thus the role of Foxg1 in regulating hair cell (HC) regeneration after birth remains unclear. Here we used Sox2CreER/+ Foxg1loxp/loxp mice and Lgr5-EGFPCreER/+ Foxg1loxp/loxp mice to conditionally knock down Foxg1 specifically in Sox2+ SCs and Lgr5+ progenitors, respectively, in neonatal mice. We found that Foxg1 conditional knockdown (cKD) in Sox2+ SCs and Lgr5+ progenitors at postnatal day (P)1 both led to large numbers of extra HCs, especially extra inner HCs (IHCs) at P7, and these extra IHCs with normal hair bundles and synapses could survive at least to P30. The EdU assay failed to detect any EdU+ SCs, while the SC number was significantly decreased in Foxg1 cKD mice, and lineage tracing data showed that much more tdTomato+ HCs originated from Sox2+ SCs in Foxg1 cKD mice compared to the control mice. Moreover, the sphere-forming assay showed that Foxg1 cKD in Lgr5+ progenitors did not significantly change their sphere-forming ability. All these results suggest that Foxg1 cKD promotes HC regeneration and leads to large numbers of extra HCs probably by inducing direct trans-differentiation of SCs and progenitors to HCs. Real-time qPCR showed that cell cycle and Notch signaling pathways were significantly down-regulated in Foxg1 cKD mice cochlear SCs. Together, this study provides new evidence for the role of Foxg1 in regulating HC regeneration from SCs and progenitors in the neonatal mouse cochlea.
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Affiliation(s)
- Shasha Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Yuan Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Ying Dong
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Lingna Guo
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Zhong Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Buwei Shao
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Jieyu Qi
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Han Zhou
- Jiangsu Provincial Key Medical Discipline (Laboratory), Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - Weijie Zhu
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Xiaoqian Yan
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Guodong Hong
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Liyan Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Xiaoli Zhang
- Jiangsu Provincial Key Medical Discipline (Laboratory), Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - Mingliang Tang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Chunjie Zhao
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Xia Gao
- Jiangsu Provincial Key Medical Discipline (Laboratory), Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - Renjie Chai
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China.
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China.
- Institute for Stem Cell and Regeneration, Chinese Academy of Science, Beijing, China.
- Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 211189, China.
- Jiangsu Provincial Key Medical Discipline (Laboratory), Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, China.
- Key Laboratory of Hearing Medicine of NHFPC, ENT Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, Shanghai Engineering Research Centre of Cochlear Implant, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China.
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24
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He D, Guo R, Zheng D, Xu M, Li P, Guo L, Gan L. Transcription factor Isl1 is dispensable for the development of the mouse prosensory region. Cytotechnology 2020; 72:407-414. [PMID: 32219582 DOI: 10.1007/s10616-020-00387-7] [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: 10/13/2019] [Accepted: 02/28/2020] [Indexed: 01/17/2023] Open
Abstract
In order to identify genes involved in the development of inner ear hair cells, we investigated the role of the transcription factor Islet-class LIM-homeodomain (LIM-HD) 1 (Isl1) in the development of the mouse prosensory region. Isl1 was deleted using the Pax2-Cre system, and deletion of both alleles was verified using cochlea sections. Changes in the number of prosensory region cells were measured to determine the effect of Isl1 on the development of the mouse prosensory region. In order to test whether Isl1 formed a protein complex with Ldb1 and Gata3, co-immunoprecipitation experiments were performed in HEK293 cells using the Flag-tagged LIM-domain of Isl1, HA-tagged LID of Ldb1 and Myc-tagged C-terminal domain of Gata3. The expression of Gata3, Sox2, Jag1 and P27 proteins in the prosensory region were not affected in Isl1-/- prosensory cells. Thus, Isl1 did not form a protein complex with Gata3 through Ldb1 in the Isl1-/- cells. Our results suggest that Isl1 may be dispensable for the development of the mouse prosensory region.
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Affiliation(s)
- Daqiang He
- College of Life Sciences, Zhejiang University, Hangzhou, 310058, Zhejiang, China
- Institute of Life Sciences, Hangzhou Normal University, Hangzhou, 310018, Zhejiang, China
- Department of Laboratory Medicine, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, Zhejiang, China
| | - Rui Guo
- College of Life Sciences, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Dongwang Zheng
- Department of Reproductive Physiology, Zhejiang Academy of Medical Sciences, HangZhou Medical College, Hangzhou, 310000, Zhejiang, China
| | - Mei Xu
- Institute of Life Sciences, Hangzhou Normal University, Hangzhou, 310018, Zhejiang, China
| | - Ping Li
- HangZhou CalyGene Bitechnology Limited Company, Hangzhou, 310013, Zhejiang, China
| | - Luming Guo
- College of Life Sciences, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Lin Gan
- College of Life Sciences, Zhejiang University, Hangzhou, 310058, Zhejiang, China.
- Institute of Life Sciences, Hangzhou Normal University, Hangzhou, 310018, Zhejiang, China.
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25
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Interaction with ectopic cochlear crista sensory epithelium disrupts basal cochlear sensory epithelium development in Lmx1a mutant mice. Cell Tissue Res 2020; 380:435-448. [PMID: 31932950 DOI: 10.1007/s00441-019-03163-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 12/18/2019] [Indexed: 12/14/2022]
Abstract
The LIM homeodomain transcription factor Lmx1a shows a dynamic expression in the developing mouse ear that stabilizes in the non-sensory epithelium. Previous work showed that Lmx1a functional null mutants have an additional sensory hair cell patch in the posterior wall of a cochlear duct and have a mix of vestibular and cochlear hair cells in the basal cochlear sensory epithelium. In E13.5 mutants, Sox2-expressing posterior canal crista is continuous with an ectopic "crista sensory epithelium" located in the outer spiral sulcus of the basal cochlear duct. The medial margin of cochlear crista is in contact with the adjacent Sox2-expressing basal cochlear sensory epithelium. By E17.5, this contact has been interrupted by the formation of an intervening non-sensory epithelium, and Atoh1 is expressed in the hair cells of both the cochlear crista and the basal cochlear sensory epithelium. Where cochlear crista was formerly associated with the basal cochlear sensory epithelium, the basal cochlear sensory epithelium lacks an outer hair cell band, and gaps are present in its associated Bmp4 expression. Further apically, where cochlear crista was never present, the cochlear sensory epithelium forms a poorly ordered but complete organ of Corti. We propose that the core prosensory posterior crista is enlarged in the mutant when the absence of Lmx1a expression allows JAG1-NOTCH signaling to propagate into the adjacent epithelium and down the posterior wall of the cochlear duct. We suggest that the cochlear crista propagates in the mutant outer spiral sulcus because it expresses Lmo4 in the absence of Lmx1a.
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26
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Novel insights into inner ear development and regeneration for targeted hearing loss therapies. Hear Res 2019; 397:107859. [PMID: 31810596 DOI: 10.1016/j.heares.2019.107859] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 11/06/2019] [Accepted: 11/25/2019] [Indexed: 02/06/2023]
Abstract
Sensorineural hearing loss is the most common sensory deficit in humans. Despite the global scale of the problem, only limited treatment options are available today. The mammalian inner ear is a highly specialized postmitotic organ, which lacks proliferative or regenerative capacity. Since the discovery of hair cell regeneration in non-mammalian species however, much attention has been placed on identifying possible strategies to reactivate similar responses in humans. The development of successful regenerative approaches for hearing loss strongly depends on a detailed understanding of the mechanisms that control human inner ear cellular specification, differentiation and function, as well as on the development of robust in vitro cellular assays, based on human inner ear cells, to study these processes and optimize therapeutic interventions. We summarize here some aspects of inner ear development and strategies to induce regeneration that have been investigated in rodents. Moreover, we discuss recent findings in human inner ear development and compare the results with findings from animal models. Finally, we provide an overview of strategies for in vitro generation of human sensory cells from pluripotent and somatic progenitors that may provide a platform for drug development and validation of therapeutic strategies in vitro.
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27
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Roccio M, Edge ASB. Inner ear organoids: new tools to understand neurosensory cell development, degeneration and regeneration. Development 2019; 146:146/17/dev177188. [PMID: 31477580 DOI: 10.1242/dev.177188] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The development of therapeutic interventions for hearing loss requires fundamental knowledge about the signaling pathways controlling tissue development as well as the establishment of human cell-based assays to validate therapeutic strategies ex vivo Recent advances in the field of stem cell biology and organoid culture systems allow the expansion and differentiation of tissue-specific progenitors and pluripotent stem cells in vitro into functional hair cells and otic-like neurons. We discuss how inner ear organoids have been developed and how they offer for the first time the opportunity to validate drug-based therapies, gene-targeting approaches and cell replacement strategies.
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Affiliation(s)
- Marta Roccio
- Inner Ear Research Laboratory, Department of Biomedical Research (DBMR), University of Bern, Bern 3008, Switzerland .,Department of Otorhinolaryngology, Head & Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern 3010, Switzerland
| | - Albert S B Edge
- Department of Otolaryngology, Harvard Medical School, Boston, MA 02115, USA.,Eaton-Peabody Laboratory, Massachusetts Eye and Ear, Boston, MA 02114, USA.,Harvard Stem Cell Institute, Cambridge, MA 02138, USA
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28
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Deng X, Liu Z, Li X, Zhou Y, Hu Z. Generation of new hair cells by DNA methyltransferase (Dnmt) inhibitor 5-azacytidine in a chemically-deafened mouse model. Sci Rep 2019; 9:7997. [PMID: 31142766 PMCID: PMC6541592 DOI: 10.1038/s41598-019-44313-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 04/02/2019] [Indexed: 02/08/2023] Open
Abstract
Regeneration of mature mammalian inner ear hair cells remains to be a challenge. This study aims to evaluate the ability of DNA methyltransferase (Dnmt) inhibitor 5-azacytidine (5-aza) to generate outer hair cells (OHCs) in a chemically-deafened adult mouse model. 5-aza was administrated into the mouse inner ear via the round window. Immunofluorescence was used to examine the expression of hair cell specific proteins following 5-aza treatment. The results showed that in the chemically-deafened mouse cochlea, new OHCs were found post 5-aza treatment, whereas OHCs were completely lost in saline-treated mice. New hair cells expressed multiple hair cell markers included Myosin VIIa, Pou4f3 and Myosin VI. Newly-generated hair cells presented in three cochlear turns and were able to survive for at least six weeks. The effects of new hair cells generation by 5-aza were concentration dependent. Quantitative PCR study indicates that 5-aza may function through Dnmt1 inhibition. The results of this report suggest that the Dnmt inhibitor 5-aza may promote hair cell regeneration in a chemically-deafened mouse model.
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Affiliation(s)
- Xin Deng
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University School of Medicine, Detroit, USA
| | - Zhenjie Liu
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University School of Medicine, Detroit, USA
| | - Xiaoyang Li
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University School of Medicine, Detroit, USA
| | - Yang Zhou
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University School of Medicine, Detroit, USA
| | - Zhengqing Hu
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University School of Medicine, Detroit, USA.
- John D. Dingell VA Medical Center, Detroit, Michigan, USA.
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29
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Zeng X, Kirkpatrick R, Hofmann G, Grillot D, Linhart V, Viviani F, Marino J, Boyer J, Graham TL, Lu Q, Wu Z, Benowitz A, Cousins R. Screen for modulators of atonal homolog 1 gene expression using notch pathway-relevant gene transcription based cellular assays. PLoS One 2018; 13:e0207140. [PMID: 30540745 PMCID: PMC6291236 DOI: 10.1371/journal.pone.0207140] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 10/25/2018] [Indexed: 12/11/2022] Open
Abstract
Atonal homolog 1 (Atoh1) is a basic helix-loop-helix 9 (bHLH) transcription factor acting downstream of Notch and is required for the differentiation of sensory hair cells in the inner ear and the specification of secretory cells during the intestinal crypt cell regeneration. Motivated by the observations that the upregulation of Atoh1 gene expression, through genetic manipulation or pharmacological inhibition of Notch signaling (e.g. γ-secretase inhibitors, GSIs), induces ectopic hair cell growth in the cochlea of the inner ear and partially restores hearing after injuries in experimental models, we decided to identify small molecule modulators of the Notch-Atoh1 pathway, which could potentially regenerate hair cells. However, the lack of cellular models of the inner ear has precluded the screening and characterization of such modulators. Here we report using a colon cancer cell line LS-174T, which displays Notch inhibition-dependent Atoh1 expression as a surrogate cellular model to screen for inducers of Atoh1 expression. We designed an Atoh1 promoter-driven luciferase assay to screen a target-annotated library of ~6000 compounds. We further developed a medium throughput, real-time quantitative RT-PCR assay measuring the endogenous Atoh1 gene expression to confirm the hits and eliminate false positives from the reporter-based screen. This strategy allowed us to successfully recover GSIs of known chemotypes. This LS-174T cell-based assay directly measures Atoh1 gene expression induced through Notch-Hes1 inhibition, and therefore offers an opportunity to identify novel cellular modulators along the Notch-Atoh1 pathway.
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Affiliation(s)
- Xin Zeng
- R&D Target Sciences, GlaxoSmithKline, Upper Providence, Collegeville, United States of America
- * E-mail: (XZ); (RC)
| | - Robert Kirkpatrick
- R&D Alternative Discovery and Development, GlaxoSmithKline, Upper Providence, Collegeville, United States of America
| | - Glenn Hofmann
- R&D Platform Technology Sciences, Drug Design and Selection, GlaxoSmithKline, Upper Providence, Collegeville, United States of America
| | - Didier Grillot
- R&D Flexible Discovery Unit, Villebon-sur-Yvette, Paris, France
| | - Valerie Linhart
- R&D Flexible Discovery Unit, Villebon-sur-Yvette, Paris, France
| | - Fabrice Viviani
- R&D Flexible Discovery Unit, Villebon-sur-Yvette, Paris, France
| | - Joseph Marino
- R&D Alternative Discovery and Development, GlaxoSmithKline, Upper Providence, Collegeville, United States of America
| | - Joseph Boyer
- R&D Statistical sciences, GlaxoSmithKline, Upper Providence, Collegeville, United States of America
| | - Taylor L. Graham
- R&D Target Sciences, GlaxoSmithKline, Upper Providence, Collegeville, United States of America
| | - Quinn Lu
- R&D Target Sciences, GlaxoSmithKline, Upper Providence, Collegeville, United States of America
| | - Zining Wu
- R&D Platform Technology Sciences, Drug Design and Selection, GlaxoSmithKline, Upper Providence, Collegeville, United States of America
| | - Andrew Benowitz
- R&D Alternative Discovery and Development, GlaxoSmithKline, Upper Providence, Collegeville, United States of America
| | - Rick Cousins
- R&D Alternative Discovery and Development, GlaxoSmithKline, Stevenage, Hertfordshire, United Kingdom
- * E-mail: (XZ); (RC)
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30
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Jahan I, Elliott KL, Fritzsch B. Understanding Molecular Evolution and Development of the Organ of Corti Can Provide Clues for Hearing Restoration. Integr Comp Biol 2018; 58:351-365. [PMID: 29718413 PMCID: PMC6104702 DOI: 10.1093/icb/icy019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The mammalian hearing organ is a stereotyped cellular assembly with orderly innervation: two types of spiral ganglion neurons (SGNs) innervate two types of differentially distributed hair cells (HCs). HCs and SGNs evolved from single neurosensory cells through gene multiplication and diversification. Independent regulation of HCs and neuronal differentiation through expression of basic helix-loop-helix transcription factors (bHLH TFs: Atoh1, Neurog1, Neurod1) led to the evolution of vestibular HC assembly and their unique type of innervation. In ancestral mammals, a vestibular organ was transformed into the organ of Corti (OC) containing a single row of inner HC (IHC), three rows of outer HCs (OHCs), several unique supporting cell types, and a peculiar innervation distribution. Restoring the OC following long-term hearing loss is complicated by the fact that the entire organ is replaced by a flat epithelium and requires reconstructing the organ from uniform undifferentiated cell types, recapitulating both evolution and development. Finding the right sequence of gene activation during development that is useful for regeneration could benefit from an understanding of the OC evolution. Toward this end, we report on Foxg1 and Lmx1a mutants that radically alter the OC cell assembly and its innervation when mutated and may have driven the evolutionary reorganization of the basilar papilla into an OC in ancestral Therapsids. Furthermore, genetically manipulating the level of bHLH TFs changes HC type and distribution and allows inference how transformation of HCs might have happened evolutionarily. We report on how bHLH TFs regulate OHC/IHC and how misexpression (Atoh1-Cre; Atoh1f/kiNeurog1) alters HC fate and supporting cell development. Using mice with altered HC types and distribution, we demonstrate innervation changes driven by HC patterning. Using these insights, we speculate on necessary steps needed to convert a random mixture of post-mitotic precursors into the orderly OC through spatially and temporally regulated critical bHLH genes in the context of other TFs to restore normal innervation patterns.
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Affiliation(s)
- Israt Jahan
- Department of Biology, University of Iowa, 129 East Jefferson, Iowa City, IA 52242, USA
| | - Karen L Elliott
- Department of Biology, University of Iowa, 129 East Jefferson, Iowa City, IA 52242, USA
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, 129 East Jefferson, Iowa City, IA 52242, USA
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31
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McPherson DR, Swalla BJ. High Time for Hair Cells: An Introduction to the Symposium on Sensory Hair Cells. Integr Comp Biol 2018; 58:276-281. [PMID: 30137315 DOI: 10.1093/icb/icy070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Sensory hair cells are highly specialized cells that form the basis for our senses of hearing, orientation to gravity, and perception of linear acceleration (head translation in space) and angular acceleration (head rotation). In many species of fish and aquatic amphibians, hair cells mediate perception of water movement through the lateral line system, and electroreceptors derived from hair cell precursors mediate electric field detection. In tunicates, cells of the mechanosensory coronal organ on the incurrent siphon meet the structural, functional, and developmental criteria to be described as hair cells, and they function to deflect large particles from entering the animal. The past two decades have witnessed significant breakthroughs in our understanding of hair cell biology and how their specialized structures influence their functions. This symposium combines the approaches of developmental biology, evolutionary biology, and physiology to share the gains of recent research in understanding hair cell function in different model systems. We brought together researchers working on sensory hair cells in organisms spanning the chordates in order to examine the depth and breadth of hair cell evolution. It is clear that these specialized cells serve a range of functions in different animals, due to evolutionary tinkering with a basic specialized cell type. This collection of papers will serve to mark the progress that has been made in this field and also stimulate the next wave of progress in this exciting field.
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Affiliation(s)
| | - Billie J Swalla
- Friday Harbor Laboratories, Friday Harbor, 620 University Road, WA 98250, USA
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Chen YC, Tsai CL, Wei YH, Wu YT, Hsu WT, Lin HC, Hsu YC. ATOH1/RFX1/RFX3 transcription factors facilitate the differentiation and characterisation of inner ear hair cell-like cells from patient-specific induced pluripotent stem cells harbouring A8344G mutation of mitochondrial DNA. Cell Death Dis 2018; 9:437. [PMID: 29740017 PMCID: PMC5941227 DOI: 10.1038/s41419-018-0488-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 03/12/2018] [Accepted: 03/16/2018] [Indexed: 11/10/2022]
Abstract
Degeneration or loss of inner ear hair cells (HCs) is irreversible and results in sensorineural hearing loss (SHL). Human-induced pluripotent stem cells (hiPSCs) have been employed in disease modelling and cell therapy. Here, we propose a transcription factor (TF)-driven approach using ATOH1 and regulatory factor of x-box (RFX) genes to generate HC-like cells from hiPSCs. Our results suggest that ATOH1/RFX1/RFX3 could significantly increase the differentiation capacity of iPSCs into MYO7AmCherry-positive cells, upregulate the mRNA expression levels of HC-related genes and promote the differentiation of HCs with more mature stereociliary bundles. To model the molecular and stereociliary structural changes involved in HC dysfunction in SHL, we further used ATOH1/RFX1/RFX3 to differentiate HC-like cells from the iPSCs from patients with myoclonus epilepsy associated with ragged-red fibres (MERRF) syndrome, which is caused by A8344G mutation of mitochondrial DNA (mtDNA), and characterised by myoclonus epilepsy, ataxia and SHL. Compared with isogenic iPSCs, MERRF-iPSCs possessed ~42–44% mtDNA with A8344G mutation and exhibited significantly elevated reactive oxygen species (ROS) production and CAT gene expression. Furthermore, MERRF-iPSC-differentiated HC-like cells exhibited significantly elevated ROS levels and MnSOD and CAT gene expression. These MERRF-HCs that had more single cilia with a shorter length could be observed only by using a non-TF method, but those with fewer stereociliary bundle-like protrusions than isogenic iPSCs-differentiated-HC-like cells could be further observed using ATOH1/RFX1/RFX3 TFs. We further analysed and compared the whole transcriptome of M1ctrl-HCs and M1-HCs after treatment with ATOH1 or ATOH1/RFX1/RFX3. We revealed that the HC-related gene transcripts in M1ctrl-iPSCs had a significantly higher tendency to be activated by ATOH1/RFX1/RFX3 than M1-iPSCs. The ATOH1/RFX1/RFX3 TF-driven approach for the differentiation of HC-like cells from iPSCs is an efficient and promising strategy for the disease modelling of SHL and can be employed in future therapeutic strategies to treat SHL patients.
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Affiliation(s)
- Yen-Chun Chen
- Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan
| | - Chia-Ling Tsai
- Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan
| | - Yau-Huei Wei
- Center for Mitochondrial Medicine and Free Radical Research Changhua Christian Hospital, Changhua, Taiwan
| | - Yu-Ting Wu
- Center for Mitochondrial Medicine and Free Radical Research Changhua Christian Hospital, Changhua, Taiwan
| | - Wei-Ting Hsu
- Department of Audiology and Speech-Language Pathology, Mackay Medical College, New Taipei City, Taiwan
| | - Hung-Ching Lin
- Department of Audiology and Speech-Language Pathology, Mackay Medical College, New Taipei City, Taiwan.,Department of Otolaryngology, Mackay Memorial Hospital, Taipei, Taiwan
| | - Yi-Chao Hsu
- Institute of Biomedical Sciences, Mackay Medical College, New Taipei City, Taiwan.
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Fritzsch B, Elliott KL. Gene, cell, and organ multiplication drives inner ear evolution. Dev Biol 2017; 431:3-15. [PMID: 28866362 DOI: 10.1016/j.ydbio.2017.08.034] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 04/27/2017] [Accepted: 08/25/2017] [Indexed: 12/14/2022]
Abstract
We review the development and evolution of the ear neurosensory cells, the aggregation of neurosensory cells into an otic placode, the evolution of novel neurosensory structures dedicated to hearing and the evolution of novel nuclei in the brain and their input dedicated to processing those novel auditory stimuli. The evolution of the apparently novel auditory system lies in duplication and diversification of cell fate transcription regulation that allows variation at the cellular level [transforming a single neurosensory cell into a sensory cell connected to its targets by a sensory neuron as well as diversifying hair cells], organ level [duplication of organ development followed by diversification and novel stimulus acquisition] and brain nuclear level [multiplication of transcription factors to regulate various neuron and neuron aggregate fate to transform the spinal cord into the unique hindbrain organization]. Tying cell fate changes driven by bHLH and other transcription factors into cell and organ changes is at the moment tentative as not all relevant factors are known and their gene regulatory network is only rudimentary understood. Future research can use the blueprint proposed here to provide both the deeper molecular evolutionary understanding as well as a more detailed appreciation of developmental networks. This understanding can reveal how an auditory system evolved through transformation of existing cell fate determining networks and thus how neurosensory evolution occurred through molecular changes affecting cell fate decision processes. Appreciating the evolutionary cascade of developmental program changes could allow identifying essential steps needed to restore cells and organs in the future.
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Affiliation(s)
- Bernd Fritzsch
- University of Iowa, Department of Biology, Iowa City, IA 52242, United States.
| | - Karen L Elliott
- University of Iowa, Department of Biology, Iowa City, IA 52242, United States
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An Atoh1-S193A Phospho-Mutant Allele Causes Hearing Deficits and Motor Impairment. J Neurosci 2017; 37:8583-8594. [PMID: 28729444 DOI: 10.1523/jneurosci.0295-17.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 06/20/2017] [Accepted: 06/29/2017] [Indexed: 12/21/2022] Open
Abstract
Atonal homolog 1 (Atoh1) is a basic helix-loop-helix (bHLH) transcription factor that is essential for the genesis, survival, and maturation of a variety of neuronal and non-neuronal cell populations, including those involved in proprioception, interoception, balance, respiration, and hearing. Such diverse functions require fine regulation at the transcriptional and protein levels. Here, we show that serine 193 (S193) is phosphorylated in Atoh1's bHLH domain in vivo Knock-in mice of both sexes bearing a GFP-tagged phospho-dead S193A allele on a null background (Atoh1S193A/lacZ) exhibit mild cerebellar foliation defects, motor impairments, partial pontine nucleus migration defects, cochlear hair cell degeneration, and profound hearing loss. We also found that Atoh1 heterozygous mice of both sexes (Atoh1lacZ/+) have adult-onset deafness. These data indicate that different cell types have different degrees of vulnerability to loss of Atoh1 function and that hypomorphic Atoh1 alleles should be considered in human hearing loss.SIGNIFICANCE STATEMENT The discovery that Atonal homolog 1 (Atoh1) governs the development of the sensory hair cells in the inner ear led to therapeutic efforts to restore these cells in cases of human deafness. Because prior studies of Atoh1-heterozygous mice did not examine or report on hearing loss in mature animals, it has not been clinical practice to sequence ATOH1 in people with deafness. Here, in seeking to understand how phosphorylation of Atoh1 modulates its effects in vivo, we discovered that inner ear hair cells are much more vulnerable to loss of Atoh1 function than other Atoh1-positive cell types and that heterozygous mice actually develop hearing loss late in life. This opens up the possibility that missense mutations in ATOH1 could increase human vulnerability to loss of hair cells because of aging or trauma.
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Elliott KL, Kersigo J, Pan N, Jahan I, Fritzsch B. Spiral Ganglion Neuron Projection Development to the Hindbrain in Mice Lacking Peripheral and/or Central Target Differentiation. Front Neural Circuits 2017; 11:25. [PMID: 28450830 PMCID: PMC5389974 DOI: 10.3389/fncir.2017.00025] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 03/28/2017] [Indexed: 12/16/2022] Open
Abstract
We investigate the importance of the degree of peripheral or central target differentiation for mouse auditory afferent navigation to the organ of Corti and auditory nuclei in three different mouse models: first, a mouse in which the differentiation of hair cells, but not central auditory nuclei neurons is compromised (Atoh1-cre; Atoh1f/f ); second, a mouse in which hair cell defects are combined with a delayed defect in central auditory nuclei neurons (Pax2-cre; Atoh1f/f ), and third, a mouse in which both hair cells and central auditory nuclei are absent (Atoh1-/-). Our results show that neither differentiated peripheral nor the central target cells of inner ear afferents are needed (hair cells, cochlear nucleus neurons) for segregation of vestibular and cochlear afferents within the hindbrain and some degree of base to apex segregation of cochlear afferents. These data suggest that inner ear spiral ganglion neuron processes may predominantly rely on temporally and spatially distinct molecular cues in the region of the targets rather than interaction with differentiated target cells for a crude topological organization. These developmental data imply that auditory neuron navigation properties may have evolved before auditory nuclei.
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Affiliation(s)
| | | | | | | | - Bernd Fritzsch
- Department of Biology, University of IowaIowa City, IA, USA
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Franco B, Malgrange B. Concise Review: Regeneration in Mammalian Cochlea Hair Cells: Help from Supporting Cells Transdifferentiation. Stem Cells 2017; 35:551-556. [PMID: 28102558 DOI: 10.1002/stem.2554] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 11/16/2016] [Accepted: 11/27/2016] [Indexed: 12/28/2022]
Abstract
It is commonly assumed that mammalian cochlear cells do not regenerate. Therefore, if hair cells are lost following an injury, no recovery could occur. However, during the first postnatal week, mice harbor some progenitor cells that retain the ability to give rise to new hair cells. These progenitor cells are in fact supporting cells. Upon hair cells loss, those cells are able to generate new hair cells both by direct transdifferentiation or following cell cycle re-entry and differentiation. However, this property of supporting cells is progressively lost after birth. Here, we review the molecular mechanisms that are involved in mammalian hair cell development and regeneration. Manipulating pathways used during development constitute good candidates for inducing hair cell regeneration after injury. Despite these promising studies, there is still no evidence for a recovery following hair cells loss in adult mammals. Stem Cells 2017;35:551-556.
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Affiliation(s)
- Bénédicte Franco
- Developmental Neurobiology Unit - GIGA-Neurosciences, University of Liège, Quartier Hôpital (CHU), B-4000, Liège, Belgium
| | - Brigitte Malgrange
- Developmental Neurobiology Unit - GIGA-Neurosciences, University of Liège, Quartier Hôpital (CHU), B-4000, Liège, Belgium
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Liu H, Li Y, Chen L, Zhang Q, Pan N, Nichols DH, Zhang WJ, Fritzsch B, He DZZ. Organ of Corti and Stria Vascularis: Is there an Interdependence for Survival? PLoS One 2016; 11:e0168953. [PMID: 28030585 PMCID: PMC5193441 DOI: 10.1371/journal.pone.0168953] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 12/08/2016] [Indexed: 01/08/2023] Open
Abstract
Cochlear hair cells and the stria vascularis are critical for normal hearing. Hair cells transduce mechanical stimuli into electrical signals, whereas the stria is responsible for generating the endocochlear potential (EP), which is the driving force for hair cell mechanotransduction. We questioned whether hair cells and the stria interdepend for survival by using two mouse models. Atoh1 conditional knockout mice, which lose all hair cells within four weeks after birth, were used to determine whether the absence of hair cells would affect function and survival of stria. We showed that stria morphology and EP remained normal for long time despite a complete loss of all hair cells. We then used a mouse model that has an abnormal stria morphology and function due to mutation of the Mitf gene to determine whether hair cells are able to survive and transduce sound signals without a normal electrochemical environment in the endolymph. A strial defect, reflected by missing intermediate cells in the stria and by reduction of EP, led to systematic outer hair cell death from the base to the apex after postnatal day 18. However, an 18-mV EP was sufficient for outer hair cell survival. Surprisingly, inner hair cell survival was less vulnerable to reduction of the EP. Our studies show that normal function of the stria is essential for adult outer hair cell survival, while the survival and normal function of the stria vascularis do not depend on functional hair cells.
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Affiliation(s)
- Huizhan Liu
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska, United States of America
| | - Yi Li
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska, United States of America
- Department of Otorhinolaryngology, Beijing Tongren Hospital, Beijing Capital Medical University, Beijing, China
| | - Lei Chen
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska, United States of America
- Chongqing Academy of Animal Science, Chongqing, China
| | - Qian Zhang
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska, United States of America
| | - Ning Pan
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - David H. Nichols
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska, United States of America
| | - Weiping J. Zhang
- Department of Pathophysiology, Second Military Medical University, Shanghai, China
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - David Z. Z. He
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska, United States of America
- * E-mail:
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Dvorakova M, Jahan I, Macova I, Chumak T, Bohuslavova R, Syka J, Fritzsch B, Pavlinkova G. Incomplete and delayed Sox2 deletion defines residual ear neurosensory development and maintenance. Sci Rep 2016; 6:38253. [PMID: 27917898 PMCID: PMC5137136 DOI: 10.1038/srep38253] [Citation(s) in RCA: 29] [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: 07/07/2016] [Accepted: 11/07/2016] [Indexed: 11/09/2022] Open
Abstract
The role of Sox2 in neurosensory development is not yet fully understood. Using mice with conditional Islet1-cre mediated deletion of Sox2, we explored the function of Sox2 in neurosensory development in a model with limited cell type diversification, the inner ear. In Sox2 conditional mutants, neurons initially appear to form normally, whereas late- differentiating neurons of the cochlear apex never form. Variable numbers of hair cells differentiate in the utricle, saccule, and cochlear base but sensory epithelium formation is completely absent in the apex and all three cristae of the semicircular canal ampullae. Hair cells differentiate only in sensory epithelia known or proposed to have a lineage relationship of neurons and hair cells. All initially formed neurons lacking hair cell targets die by apoptosis days after they project toward non-existing epithelia. Therefore, late neuronal development depends directly on Sox2 for differentiation and on the survival of hair cells, possibly derived from common neurosensory precursors.
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Affiliation(s)
- Martina Dvorakova
- Institute of Biotechnology CAS, Prague, Czechia
- Faculty of Science, Charles University, Prague, Czechia
| | - Israt Jahan
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - Iva Macova
- Institute of Biotechnology CAS, Prague, Czechia
- Faculty of Science, Charles University, Prague, Czechia
| | | | | | - Josef Syka
- Institute of Experimental Medicine CAS, Prague, Czechia
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, USA
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Basch ML, Brown RM, Jen H, Groves AK. Where hearing starts: the development of the mammalian cochlea. J Anat 2016; 228:233-54. [PMID: 26052920 PMCID: PMC4718162 DOI: 10.1111/joa.12314] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2015] [Indexed: 12/11/2022] Open
Abstract
The mammalian cochlea is a remarkable sensory organ, capable of perceiving sound over a range of 10(12) in pressure, and discriminating both infrasonic and ultrasonic frequencies in different species. The sensory hair cells of the mammalian cochlea are exquisitely sensitive, responding to atomic-level deflections at speeds on the order of tens of microseconds. The number and placement of hair cells are precisely determined during inner ear development, and a large number of developmental processes sculpt the shape, size and morphology of these cells along the length of the cochlear duct to make them optimally responsive to different sound frequencies. In this review, we briefly discuss the evolutionary origins of the mammalian cochlea, and then describe the successive developmental processes that lead to its induction, cell cycle exit, cellular patterning and the establishment of topologically distinct frequency responses along its length.
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Affiliation(s)
- Martin L. Basch
- Department of NeuroscienceBaylor College of MedicineHoustonTXUSA
| | - Rogers M. Brown
- Program in Developmental BiologyBaylor College of MedicineHoustonTXUSA
| | - Hsin‐I Jen
- Program in Developmental BiologyBaylor College of MedicineHoustonTXUSA
| | - Andrew K. Groves
- Department of NeuroscienceBaylor College of MedicineHoustonTXUSA
- Program in Developmental BiologyBaylor College of MedicineHoustonTXUSA
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonTXUSA
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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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Gillespie LN, Richardson RT, Nayagam BA, Wise AK. Treating hearing disorders with cell and gene therapy. J Neural Eng 2015; 11:065001. [PMID: 25420002 DOI: 10.1088/1741-2560/11/6/065001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Hearing loss is an increasing problem for a substantial number of people and, with an aging population, the incidence and severity of hearing loss will become more significant over time. There are very few therapies currently available to treat hearing loss, and so the development of new therapeutic strategies for hearing impaired individuals is of paramount importance to address this unmet clinical need. Most forms of hearing loss are progressive in nature and therefore an opportunity exists to develop novel therapeutic approaches to slow or halt hearing loss progression, or even repair or replace lost hearing function. Numerous emerging technologies have potential as therapeutic options. This paper details the potential of cell- and gene-based therapies to provide therapeutic agents to protect sensory and neural cells from various insults known to cause hearing loss; explores the potential of replacing lost sensory and nerve cells using gene and stem cell therapy; and describes the considerations for clinical translation and the challenges that need to be overcome.
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Jahan I, Pan N, Kersigo J, Fritzsch B. Neurog1 can partially substitute for Atoh1 function in hair cell differentiation and maintenance during organ of Corti development. Development 2015. [PMID: 26209643 DOI: 10.1242/dev.123091] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Atoh1, a basic helix-loop-helix (bHLH) transcription factor (TF), is essential for the differentiation of hair cells (HCs), mechanotransducers that convert sound into auditory signals in the mammalian organ of Corti (OC). Previous work demonstrated that replacing mouse Atoh1 with the fly ortholog atonal rescues HC differentiation, indicating functional replacement by other bHLH genes. However, replacing Atoh1 with Neurog1 resulted in reduced HC differentiation compared with transient Atoh1 expression in a 'self-terminating' Atoh1 conditional null mouse (Atoh1-Cre; Atoh1(f/f)). We now show that combining Neurog1 in one allele with removal of floxed Atoh1 in a self-terminating conditional mutant (Atoh1-Cre; Atoh1(f/kiNeurog1)) mouse results in significantly more differentiated inner HCs and outer HCs that have a prolonged longevity of 9 months compared with Atoh1 self-terminating littermates. Stereocilia bundles are partially disorganized, disoriented and not HC type specific. Replacement of Atoh1 with Neurog1 maintains limited expression of Pou4f3 and Barhl1 and rescues HCs quantitatively, but not qualitatively. OC patterning and supporting cell differentiation are also partially disrupted. Diffusible factors involved in patterning are reduced (Fgf8) and factors involved in cell-cell interactions are affected (Jag1, Hes5). Despite the presence of many HCs with stereocilia these mice are deaf, possibly owing to HC and OC patterning defects. This study provides a novel approach to disrupt OC development through modulating the HC-specific intracellular TF network. The resulting disorganized OC indicates that normally differentiated HCs act as 'self-organizers' for OC development and that Atoh1 plays a crucial role to initiate HC stereocilia differentiation independently of HC viability.
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Affiliation(s)
- Israt Jahan
- Department of Biology, College of Liberal Arts & Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - Ning Pan
- Department of Biology, College of Liberal Arts & Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - Jennifer Kersigo
- Department of Biology, College of Liberal Arts & Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - Bernd Fritzsch
- Department of Biology, College of Liberal Arts & Sciences, University of Iowa, Iowa City, IA 52242, USA
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Jahan I, Pan N, Elliott KL, Fritzsch B. The quest for restoring hearing: Understanding ear development more completely. Bioessays 2015. [PMID: 26208302 DOI: 10.1002/bies.201500044] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Neurosensory hearing loss is a growing problem of super-aged societies. Cochlear implants can restore some hearing, but rebuilding a lost hearing organ would be superior. Research has discovered many cellular and molecular steps to develop a hearing organ but translating those insights into hearing organ restoration remains unclear. For example, we cannot make various hair cell types and arrange them into their specific patterns surrounded by the right type of supporting cells in the right numbers. Our overview of the topologically highly organized and functionally diversified cellular mosaic of the mammalian hearing organ highlights what is known and unknown about its development. Following this analysis, we suggest critical steps to guide future attempts toward restoration of a functional organ of Corti. We argue that generating mutant mouse lines that mimic human pathology to fine-tune attempts toward long-term functional restoration are needed to go beyond the hope generated by restoring single hair cells in postnatal sensory epithelia.
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Affiliation(s)
- Israt Jahan
- Department of Biology, CLAS, University of Iowa, Iowa City, IA, USA
| | - Ning Pan
- Department of Biology, CLAS, University of Iowa, Iowa City, IA, USA
| | - Karen L Elliott
- Department of Biology, CLAS, University of Iowa, Iowa City, IA, USA
| | - Bernd Fritzsch
- Department of Biology, CLAS, University of Iowa, Iowa City, IA, USA
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Atkinson PJ, Huarcaya Najarro E, Sayyid ZN, Cheng AG. Sensory hair cell development and regeneration: similarities and differences. Development 2015; 142:1561-71. [PMID: 25922522 DOI: 10.1242/dev.114926] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Sensory hair cells are mechanoreceptors of the auditory and vestibular systems and are crucial for hearing and balance. In adult mammals, auditory hair cells are unable to regenerate, and damage to these cells results in permanent hearing loss. By contrast, hair cells in the chick cochlea and the zebrafish lateral line are able to regenerate, prompting studies into the signaling pathways, morphogen gradients and transcription factors that regulate hair cell development and regeneration in various species. Here, we review these findings and discuss how various signaling pathways and factors function to modulate sensory hair cell development and regeneration. By comparing and contrasting development and regeneration, we also highlight the utility and limitations of using defined developmental cues to drive mammalian hair cell regeneration.
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Affiliation(s)
- Patrick J Atkinson
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Elvis Huarcaya Najarro
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Zahra N Sayyid
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alan G Cheng
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
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Fritzsch B, Pan N, Jahan I, Elliott KL. Inner ear development: building a spiral ganglion and an organ of Corti out of unspecified ectoderm. Cell Tissue Res 2015; 361:7-24. [PMID: 25381571 PMCID: PMC4426086 DOI: 10.1007/s00441-014-2031-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 10/09/2014] [Indexed: 01/21/2023]
Abstract
The mammalian inner ear develops from a placodal thickening into a complex labyrinth of ducts with five sensory organs specialized to detect position and movement in space. The mammalian ear also develops a spiraled cochlear duct containing the auditory organ, the organ of Corti (OC), specialized to translate sound into hearing. Development of the OC from a uniform sheet of ectoderm requires unparalleled precision in the topological developmental engineering of four different general cell types, namely sensory neurons, hair cells, supporting cells, and general otic epithelium, into a mosaic of ten distinctly recognizable cell types in and around the OC, each with a unique distribution. Moreover, the OC receives unique innervation by ear-derived spiral ganglion afferents and brainstem-derived motor neurons as efferents and requires neural-crest-derived Schwann cells to form myelin and neural-crest-derived cells to induce the stria vascularis. This transformation of a sheet of cells into a complicated interdigitating set of cells necessitates the orchestrated expression of multiple transcription factors that enable the cellular transformation from ectoderm into neurosensory cells forming the spiral ganglion neurons (SGNs), while simultaneously transforming the flat epithelium into a tube, the cochlear duct, housing the OC. In addition to the cellular and conformational changes forming the cochlear duct with the OC, changes in the surrounding periotic mesenchyme form passageways for sound to stimulate the OC. We review molecular developmental data, generated predominantly in mice, in order to integrate the well-described expression changes of transcription factors and their actions, as revealed in mutants, in the formation of SGNs and OC in the correct position and orientation with suitable innervation. Understanding the molecular basis of these developmental changes leading to the formation of the mammalian OC and highlighting the gaps in our knowledge might guide in vivo attempts to regenerate this most complicated cellular mosaic of the mammalian body for the reconstitution of hearing in a rapidly growing population of aging people suffering from hearing loss.
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Affiliation(s)
- Bernd Fritzsch
- College of Liberal Arts and Sciences, Department of Biology, University of Iowa, 143 BB, 123 Jefferson Avenue, Iowa City, IA 52242, USA,
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Kersigo J, Fritzsch B. Inner ear hair cells deteriorate in mice engineered to have no or diminished innervation. Front Aging Neurosci 2015; 7:33. [PMID: 25852547 PMCID: PMC4364252 DOI: 10.3389/fnagi.2015.00033] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 02/28/2015] [Indexed: 12/14/2022] Open
Abstract
The innervation of the inner ear critically depends on the two neurotrophins Ntf3 and Bdnf. In contrast to this molecularly well-established dependency, evidence regarding the need of innervation for long-term maintenance of inner ear hair cells is inconclusive, due to experimental variability. Mutant mice that lack both neurotrophins could shed light on the long-term consequences of innervation loss on hair cells without introducing experimental variability, but do not survive after birth. Mutant mice with conditional deletion of both neurotrophins lose almost all innervation by postnatal day 10 and show an initially normal development of hair cells by this stage. No innervation remains after 3 weeks and complete loss of all innervation results in near complete loss of outer and many inner hair cells of the organ of Corti within 4 months. Mutants that retain one allele of either neurotrophin have only partial loss of innervation of the organ of Corti and show a longer viability of cochlear hair cells with more profound loss of inner hair cells. By 10 months, hair cells disappear with a base to apex progression, proportional to the residual density of innervation and similar to carboplatin ototoxicity. Similar to reports of hair cell loss after aminoglycoside treatment, blobbing of stereocilia of apparently dying hair cells protrude into the cochlear duct. Denervation of vestibular sensory epithelia for several months also resulted in variable results, ranging from unusual hair cells resembling the aberrations found in the organ of Corti, to near normal hair cells in the canal cristae. Fusion and/or resorption of stereocilia and loss of hair cells follows a pattern reminiscent of Myo6 and Cdc42 null mice. Our data support a role of innervation for long-term maintenance but with a remarkable local variation that needs to be taken into account when attempting regeneration of the organ of Corti.
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Affiliation(s)
| | - Bernd Fritzsch
- Department of Biology, University of IowaIowa City, IA, USA
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Jahan I, Pan N, Fritzsch B. Opportunities and limits of the one gene approach: the ability of Atoh1 to differentiate and maintain hair cells depends on the molecular context. Front Cell Neurosci 2015; 9:26. [PMID: 25698932 PMCID: PMC4318345 DOI: 10.3389/fncel.2015.00026] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 01/14/2015] [Indexed: 02/03/2023] Open
Abstract
Atoh1 (Math1) was the first gene discovered in ear development that showed no hair cell (HC) differentiation when absent and could induce HC differentiation when misexpressed. These data implied that Atoh1 was both necessary and sufficient for hair cell development. However, other gene mutations also result in loss of initially forming HCs, notably null mutants for Pou4f3, Barhl1, and Gfi1. HC development and maintenance also depend on the expression of other genes (Sox2, Eya1, Gata3, Pax2) and several genes have been identified that can induce HCs when misexpressed (Jag1) or knocked out (Lmo4). In the ear Atoh1 is not only expressed in HCs but also in some supporting cells and neurons that do not differentiate into HCs. Simple removal of one gene, Neurod1, can de-repress Atoh1 and turns those neurons into HCs suggesting that Neurod1 blocks Atoh1 function in neurons. Atoh1 expression in inner pillar cells may also be blocked by too many Hes/Hey factors but conversion into HCs has only partially been achieved through Hes/Hey removal. Detailed analysis of cell cycle exit confirmed an apex to base cell cycle exit progression of HCs of the organ of Corti. In contrast, Atoh1 expression progresses from the base toward the apex with a variable delay relative to the cell cycle exit. Most HCs exit the cell cycle and are thus defined as precursors before Atoh1 is expressed. Atoh1 is a potent differentiation factor but can differentiate and maintain HCs only in the ear and when other factors are co-expressed. Upstream factors are essential to regulate Atoh1 level of expression duration while downstream, co-activated by other factors, will define the context of Atoh1 action. We suggest that these insights need to be taken into consideration and approaches beyond the simple Atoh1 expression need to be designed able to generate the radial and longitudinal variations in hair cell types for normal function of the organ of Corti.
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Affiliation(s)
- Israt Jahan
- Department of Biology, University of Iowa Iowa City, IA, USA
| | - Ning Pan
- Department of Biology, University of Iowa Iowa City, IA, USA
| | - Bernd Fritzsch
- Department of Biology, University of Iowa Iowa City, IA, USA
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Richardson RT, Atkinson PJ. Atoh1 gene therapy in the cochlea for hair cell regeneration. Expert Opin Biol Ther 2015; 15:417-30. [DOI: 10.1517/14712598.2015.1009889] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Willaredt MA, Schlüter T, Nothwang HG. The gene regulatory networks underlying formation of the auditory hindbrain. Cell Mol Life Sci 2015; 72:519-535. [PMID: 25332098 PMCID: PMC11113740 DOI: 10.1007/s00018-014-1759-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 09/24/2014] [Accepted: 10/09/2014] [Indexed: 01/28/2023]
Abstract
Development and evolution of auditory hindbrain nuclei are two major unsolved issues in hearing research. Recent characterization of transgenic mice identified the rhombomeric origins of mammalian auditory nuclei and unraveled genes involved in their formation. Here, we provide an overview on these data by assembling them into rhombomere-specific gene regulatory networks (GRNs), as they underlie developmental and evolutionary processes. To explore evolutionary mechanisms, we compare the GRNs operating in the mammalian auditory hindbrain with data available from the inner ear and other vertebrate groups. Finally, we propose that the availability of genomic sequences from all major vertebrate taxa and novel genetic techniques for non-model organisms provide an unprecedented opportunity to investigate development and evolution of the auditory hindbrain by comparative molecular approaches. The dissection of the molecular mechanisms leading to auditory structures will also provide an important framework for auditory processing disorders, a clinical problem difficult to tackle so far. These data will, therefore, foster basic and clinical hearing research alike.
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Affiliation(s)
- Marc A Willaredt
- Neurogenetics group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany.
| | - Tina Schlüter
- Neurogenetics group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Hans Gerd Nothwang
- Neurogenetics group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany.
- Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany.
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Nakajima Y. Signaling regulating inner ear development: cell fate determination, patterning, morphogenesis, and defects. Congenit Anom (Kyoto) 2015; 55:17-25. [PMID: 25040109 DOI: 10.1111/cga.12072] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Accepted: 06/07/2014] [Indexed: 12/28/2022]
Abstract
The membranous labyrinth of the inner ear is a highly complex organ that detects sound and balance. Developmental defects in the inner ear cause congenital hearing loss and balance disorders. The membranous labyrinth consists of three semicircular ducts, the utricle, saccule, and endolymphatic ducts, and the cochlear duct. These complex structures develop from the simple otic placode, which is established in the cranial ectoderm adjacent to the neural crest at the level of the hindbrain at the early neurula stage. During development, the otic placode invaginates to form the otic vesicle, which subsequently gives rise to neurons for the vestibulocochlear ganglion, the non-sensory and sensory epithelia of the membranous labyrinth that includes three ampullary crests, two maculae, and the organ of Corti. Combined paracrine and autocrine signals including fibroblast growth factor, Wnt, retinoic acid, hedgehog, and bone morphogenetic protein regulate fate determination, axis formation, and morphogenesis in the developing inner ear. Juxtacrine signals mediated by Notch pathways play a role in establishing the sensory epithelium, which consists of mechanosensory hair cells and supporting cells. The highly differentiated organ of Corti, which consists of uniformly oriented inner/outer hair cells and specific supporting cells, develops during fetal development. Developmental alterations/arrest causes congenital malformations in the inner ear in a spatiotemporal-restricted manner. A clearer understanding of the mechanisms underlying inner ear development is important not only for the management of patients with congenital inner ear malformations, but also for the development of regenerative therapy for impaired function.
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Affiliation(s)
- Yuji Nakajima
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Osaka City University, Osaka, Japan
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