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Lipovsek M. Comparative biology of the amniote vestibular utricle. Hear Res 2024; 448:109035. [PMID: 38763033 DOI: 10.1016/j.heares.2024.109035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 05/09/2024] [Accepted: 05/13/2024] [Indexed: 05/21/2024]
Abstract
The sensory epithelia of the auditory and vestibular systems of vertebrates have shared developmental and evolutionary histories. However, while the auditory epithelia show great variation across vertebrates, the vestibular sensory epithelia appear seemingly more conserved. An exploration of the current knowledge of the comparative biology of the amniote utricle, a vestibular sensory epithelium that senses linear acceleration, shows interesting instances of variability between birds and mammals. The distribution of sensory hair cell types, the position of the line of hair bundle polarity reversal and the properties of supporting cells show marked differences, likely impacting vestibular function and hair cell regeneration potential.
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Affiliation(s)
- Marcela Lipovsek
- Ear Institute, Faculty of Brain Sciences, University College London, London, UK.
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2
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Wang S, Chakraborty S, Fu Y, Lee MP, Liu J, Waldhaus J. 3D reconstruction of the mouse cochlea from scRNA-seq data suggests morphogen-based principles in apex-to-base specification. Dev Cell 2024:S1534-5807(24)00196-5. [PMID: 38593801 DOI: 10.1016/j.devcel.2024.03.028] [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: 09/20/2022] [Revised: 04/03/2023] [Accepted: 03/13/2024] [Indexed: 04/11/2024]
Abstract
In the mammalian auditory system, frequency discrimination depends on numerous morphological and physiological properties of the organ of Corti, which gradually change along the apex-to-base (tonotopic) axis of the organ. For example, the basilar membrane stiffness changes tonotopically, thus affecting the tuning properties of individual hair cells. At the molecular level, those frequency-specific characteristics are mirrored by gene expression gradients; however, the molecular mechanisms controlling tonotopic gene expression in the mouse cochlea remain elusive. Through analyzing single-cell RNA sequencing (scRNA-seq) data from E12.5 and E14.5 time points, we predicted that morphogens, rather than a cell division-associated mechanism, confer spatial identity in the extending cochlea. Subsequently, we reconstructed the developing cochlea in 3D space from scRNA-seq data to investigate the molecular pathways mediating positional information. The retinoic acid (RA) and hedgehog pathways were found to form opposing apex-to-base gradients, and functional interrogation using mouse cochlear explants suggested that both pathways jointly specify the longitudinal axis.
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Affiliation(s)
- Shuze Wang
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Saikat Chakraborty
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Yujuan Fu
- Biomedical Informatics and Medical Education, University of Washington, Seattle, WA 98195, USA
| | - Mary P Lee
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jie Liu
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Joerg Waldhaus
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI 48109, USA.
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3
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Kagoshima H, Ohnishi H, Yamamoto R, Yasumoto A, Tona Y, Nakagawa T, Omori K, Yamamoto N. EBF1 Limits the Numbers of Cochlear Hair and Supporting Cells and Forms the Scala Tympani and Spiral Limbus during Inner Ear Development. J Neurosci 2024; 44:e1060232023. [PMID: 38176908 PMCID: PMC10869149 DOI: 10.1523/jneurosci.1060-23.2023] [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: 06/07/2023] [Revised: 11/12/2023] [Accepted: 12/13/2023] [Indexed: 01/06/2024] Open
Abstract
Early B-cell factor 1 (EBF1) is a basic helix-loop-helix transcription factor essential for the differentiation of various tissues. Our single-cell RNA sequencing data suggest that Ebf1 is expressed in the sensory epithelium of the mouse inner ear. Here, we found that the murine Ebf1 gene and its protein are expressed in the prosensory domain of the inner ear, medial region of the cochlear duct floor, otic mesenchyme, and cochleovestibular ganglion. Ebf1 deletion in mice results in incomplete formation of the spiral limbus and scala tympani, increased number of cells in the organ of Corti and Kölliker's organ, and aberrant course of the spiral ganglion axons. Ebf1 deletion in the mouse cochlear epithelia caused the proliferation of SOX2-positive cochlear cells at E13.5, indicating that EBF1 suppresses the proliferation of the prosensory domain and cells of Kölliker's organ to facilitate the development of appropriate numbers of hair and supporting cells. Furthermore, mice with deletion of cochlear epithelium-specific Ebf1 showed poor postnatal hearing function. Our results suggest that Ebf1 is essential for normal auditory function in mammals.
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Affiliation(s)
- Hiroki Kagoshima
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Hiroe Ohnishi
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Ryosuke Yamamoto
- Biological Sciences, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5, Canada
| | - Akiyoshi Yasumoto
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Yosuke Tona
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Takayuki Nakagawa
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Koichi Omori
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Norio Yamamoto
- Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
- Department of Otolaryngology, Kobe City Medical Center General Hospital, Hyogo 650-0047, Japan
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McGovern MM, Hosamani IV, Niu Y, Nguyen KY, Zong C, Groves AK. Expression of Atoh1, Gfi1, and Pou4f3 in the mature cochlea reprograms nonsensory cells into hair cells. Proc Natl Acad Sci U S A 2024; 121:e2304680121. [PMID: 38266052 PMCID: PMC10835112 DOI: 10.1073/pnas.2304680121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 12/08/2023] [Indexed: 01/26/2024] Open
Abstract
Mechanosensory hair cells of the mature mammalian organ of Corti do not regenerate; consequently, loss of hair cells leads to permanent hearing loss. Although nonmammalian vertebrates can regenerate hair cells from neighboring supporting cells, many humans with severe hearing loss lack both hair cells and supporting cells, with the organ of Corti being replaced by a flat epithelium of nonsensory cells. To determine whether the mature cochlea can produce hair cells in vivo, we reprogrammed nonsensory cells adjacent to the organ of Corti with three hair cell transcription factors: Gfi1, Atoh1, and Pou4f3. We generated numerous hair cell-like cells in nonsensory regions of the cochlea and new hair cells continued to be added over a period of 9 wk. Significantly, cells adjacent to reprogrammed hair cells expressed markers of supporting cells, suggesting that transcription factor reprogramming of nonsensory cochlear cells in adult animals can generate mosaics of sensory cells like those seen in the organ of Corti. Generating such sensory mosaics by reprogramming may represent a potential strategy for hearing restoration in humans.
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Affiliation(s)
- Melissa M McGovern
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030
| | - Ishwar V Hosamani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
| | - Yichi Niu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
| | - Ken Y Nguyen
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030
| | - Chenghang Zong
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
| | - Andrew K Groves
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
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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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Veithen M, Huyghe A, Van Den Ackerveken P, Fukada SI, Kokubo H, Breuskin I, Nguyen L, Delacroix L, Malgrange B. Sox9 Inhibits Cochlear Hair Cell Fate by Upregulating Hey1 and HeyL Antagonists of Atoh1. Cells 2023; 12:2148. [PMID: 37681879 PMCID: PMC10486728 DOI: 10.3390/cells12172148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 08/23/2023] [Accepted: 08/24/2023] [Indexed: 09/09/2023] Open
Abstract
It is widely accepted that cell fate determination in the cochlea is tightly controlled by different transcription factors (TFs) that remain to be fully defined. Here, we show that Sox9, initially expressed in the entire sensory epithelium of the cochlea, progressively disappears from differentiating hair cells (HCs) and is finally restricted to supporting cells (SCs). By performing ex vivo electroporation of E13.5-E14.5 cochleae, we demonstrate that maintenance of Sox9 expression in the progenitors committed to HC fate blocks their differentiation, even if co-expressed with Atoh1, a transcription factor necessary and sufficient to form HC. Sox9 inhibits Atoh1 transcriptional activity by upregulating Hey1 and HeyL antagonists, and genetic ablation of these genes induces extra HCs along the cochlea. Although Sox9 suppression from sensory progenitors ex vivo leads to a modest increase in the number of HCs, it is not sufficient in vivo to induce supernumerary HC production in an inducible Sox9 knockout model. Taken together, these data show that Sox9 is downregulated from nascent HCs to allow the unfolding of their differentiation program. This may be critical for future strategies to promote fully mature HC formation in regeneration approaches.
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Affiliation(s)
- Mona Veithen
- Laboratory of Developmental Neurobiology, GIGA-Neurosciences, University of Liege, 4000 Liege, Belgium; (M.V.); (A.H.); (P.V.D.A.); (I.B.); (L.D.)
| | - Aurélia Huyghe
- Laboratory of Developmental Neurobiology, GIGA-Neurosciences, University of Liege, 4000 Liege, Belgium; (M.V.); (A.H.); (P.V.D.A.); (I.B.); (L.D.)
| | - Priscilla Van Den Ackerveken
- Laboratory of Developmental Neurobiology, GIGA-Neurosciences, University of Liege, 4000 Liege, Belgium; (M.V.); (A.H.); (P.V.D.A.); (I.B.); (L.D.)
| | - So-ichiro Fukada
- Laboratory of Stem Cell Regeneration and Adaptation, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka 565-0871, Japan;
| | - Hiroki Kokubo
- Graduate School of Biomedical and Health Sciences, 1-2-3 Kasumi, Minamiku, Hiroshima 734-8551, Japan;
| | - Ingrid Breuskin
- Laboratory of Developmental Neurobiology, GIGA-Neurosciences, University of Liege, 4000 Liege, Belgium; (M.V.); (A.H.); (P.V.D.A.); (I.B.); (L.D.)
| | - Laurent Nguyen
- Laboratory of Molecular Regulation of Neurogenesis, GIGA-Neurosciences, University of Liege, 4000 Liege, Belgium;
| | - Laurence Delacroix
- Laboratory of Developmental Neurobiology, GIGA-Neurosciences, University of Liege, 4000 Liege, Belgium; (M.V.); (A.H.); (P.V.D.A.); (I.B.); (L.D.)
| | - Brigitte Malgrange
- Laboratory of Developmental Neurobiology, GIGA-Neurosciences, University of Liege, 4000 Liege, Belgium; (M.V.); (A.H.); (P.V.D.A.); (I.B.); (L.D.)
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7
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Blinkiewicz PV, Long MR, Stoner ZA, Ketchum EM, Sheltz-Kempf SN, Duncan JS. Gata3 is required in late proneurosensory development for proper sensory cell formation and organization. Sci Rep 2023; 13:12573. [PMID: 37537240 PMCID: PMC10400699 DOI: 10.1038/s41598-023-39707-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 07/29/2023] [Indexed: 08/05/2023] Open
Abstract
It has previously been shown that the zinc-finger transcription factor Gata3 has dynamic expression within the inner ear throughout embryonic development and is essential for cochlear neurosensory development. However, the temporal window for which Gata3 is required for proper formation of the cochlear neurosensory epithelia remains unclear. To investigate the role of Gata3 in cochlear neurosensory development in the late prosensory stages, we used the Sox2-creERT2 mouse line to target and conditionally delete Gata3 at E11.5, a timepoint before cells have fully committed to a neurosensory fate. While the inner ears of Sox2-creERT2: Gata3 f/f mice appear normal with no gross structural defects, the sensory cells in the organ of Corti are partially lost and disorganized in an increasing severity from base to apex. Additionally, spiral ganglion neurons display aberrant peripheral projections, including increased distances between radial bundles and disorganization upon reaching the organ of Corti. Furthermore, heterozygous Sox2-creERT2: Gata3 f/+ mice show a reduced aberrant phenotype in comparison to the homozygous mutant, supporting the hypothesis that Gata3 is not only required for proper formation at the later proneurosensory stage, but also that a specific expression level of Gata3 is required. Therefore, this study provides evidence that Gata3 plays a time-sensitive and dose-dependent role in the development of sensory and neuronal cells in late proneurosensory stages.
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Affiliation(s)
- Paige V Blinkiewicz
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, USA
| | - Makayla R Long
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, USA
| | - Zachary A Stoner
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, USA.
- Section On Sensory Cell Regeneration and Development, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Elizabeth M Ketchum
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, USA
| | | | - Jeremy S Duncan
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, USA.
- Department of Biomedical Sciences, Western Michigan School of Medicine, Kalamazoo, MI, USA.
- Department of Neurology, University of Minnesota, Minneapolis, MN, USA.
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Nakamura T, Sakaguchi H, Mohri H, Ninoyu Y, Goto A, Yamaguchi T, Hishikawa Y, Matsuda M, Saito N, Ueyama T. Dispensable role of Rac1 and Rac3 after cochlear hair cell specification. J Mol Med (Berl) 2023; 101:843-854. [PMID: 37204479 PMCID: PMC10300165 DOI: 10.1007/s00109-023-02317-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 04/03/2023] [Accepted: 04/11/2023] [Indexed: 05/20/2023]
Abstract
Rac small GTPases play important roles during embryonic development of the inner ear; however, little is known regarding their function in cochlear hair cells (HCs) after specification. Here, we revealed the localization and activation of Racs in cochlear HCs using GFP-tagged Rac plasmids and transgenic mice expressing a Rac1-fluorescence resonance energy transfer (FRET) biosensor. Furthermore, we employed Rac1-knockout (Rac1-KO, Atoh1-Cre;Rac1flox/flox) and Rac1 and Rac3 double KO (Rac1/Rac3-DKO, Atoh1-Cre;Rac1flox/flox;Rac3-/-) mice, under the control of the Atoh1 promoter. However, both Rac1-KO and Rac1/Rac3-DKO mice exhibited normal cochlear HC morphology at 13 weeks of age and normal hearing function at 24 weeks of age. No hearing vulnerability was observed in young adult (6-week-old) Rac1/Rac3-DKO mice even after intense noise exposure. Consistent with prior reports, the results from Atoh1-Cre;tdTomato mice confirmed that the Atoh1 promoter became functional only after embryonic day 14 when the sensory HC precursors exit the cell cycle. Taken together, these findings indicate that although Rac1 and Rac3 contribute to the early development of sensory epithelia in cochleae, as previously shown, they are dispensable for the maturation of cochlear HCs in the postmitotic state or for hearing maintenance following HC maturation. KEY MESSAGES: Mice with Rac1 and Rac3 deletion were generated after HC specification. Knockout mice exhibit normal cochlear hair cell morphology and hearing. Racs are dispensable for hair cells in the postmitotic state after specification. Racs are dispensable for hearing maintenance after HC maturation.
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Affiliation(s)
- Takashi Nakamura
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe, 657-8501, Japan
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Hirofumi Sakaguchi
- Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Hiroaki Mohri
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe, 657-8501, Japan
| | - Yuzuru Ninoyu
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe, 657-8501, Japan
| | - Akihiro Goto
- Graduate School of Biostudies, Kyoto University, Kyoto, 606-8315, Japan
| | - Taro Yamaguchi
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, 573-0101, Japan
| | - Yoshitaka Hishikawa
- Department of Anatomy, Histochemistry and Cell Biology, Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Michiyuki Matsuda
- Graduate School of Biostudies, Kyoto University, Kyoto, 606-8315, Japan
| | - Naoaki Saito
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe, 657-8501, Japan
| | - Takehiko Ueyama
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe, 657-8501, Japan.
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9
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Blinkiewicz PV, Long MR, Stoner ZA, Ketchum EM, Sheltz-Kempf SN, Duncan JS. Gata3 is Required in Late Proneurosensory Development for Proper Sensory Cell Formation and Organization. RESEARCH SQUARE 2023:rs.3.rs-2747944. [PMID: 37090645 PMCID: PMC10120746 DOI: 10.21203/rs.3.rs-2747944/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
It has been previously shown that zinc-finger transcription factor Gata3 has dynamic expression within the inner ear throughout embryonic development and is essential for cochlear neurosensory development. However, the temporal window to which Gata3 is required for the formation of the cochlear neurosensory epithelia remains unclear. To investigate the role of Gata3 on cochlear neurosensory development in the late prosensory stages, we used the Sox2-cre ERT2 mouse line to target and conditionally delete Gata3 at E11.5 before the cells have fully committed to a neurosensory fate. While the inner ears of Sox2-cre ERT2 : Gata3 f/f mice appear morphologically normal, the sensory cells in the organ of Corti are partially lost and disorganized in a basal to apical gradient with the apex demonstrating the more severe phenotype. Additionally, spiral ganglion neurons display aberrant peripheral projections, such as increased distances between radial bundles and disorganization upon reaching the organ of Corti. Furthermore, heterozygous Sox2-cre ERT2 : Gata3 f/+ mice show a reduced phenotype in comparison to the homozygous mutant, supporting the concept that Gata3 is not only required for proper formation at the later proneurosensory stage, but also that a specific level of Gata3 is required. Therefore, our studies confirm that Gata3 plays a time-sensitive and dose-dependent role in the development of sensory cells in the late proneurosensory stages.
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10
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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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11
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Nuclear Translocation Triggered at the Onset of Hearing in Cochlear Inner Hair Cells of Rats and Mice. J Assoc Res Otolaryngol 2023:10.1007/s10162-023-00894-2. [PMID: 36932316 DOI: 10.1007/s10162-023-00894-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 02/21/2023] [Indexed: 03/19/2023] Open
Abstract
PURPOSE Nuclear position is precisely orchestrated during cell division, migration, and maturation of cells and tissues. Here we report a previously unrecognized, programmed movement of the nucleus in rat and mouse cochlear inner hair cells (IHCs) coinciding with the functional maturation of inner hair cells around the onset of hearing. METHODS We measured hair cell length and nuclear position from confocal scans of immunofluorescence-labeled hair cells from whole-mount cochlear preparations throughout post-natal development. RESULTS In early post-natal days, the IHC experiences a period of sustained growth, during which the nucleus sits at the very basal pole of the cell, far from the apically located mechano-transducing stereocilia, but close to where synapses with primary afferent and efferent neurons are forming. After IHCs reach their final length, the nucleus moves to occupy a new position half-way along the length of the cell. Nuclear translocation begins in the middle turn, completes throughout the cochlea within 2-3 days, and coincides with the emergence of endolymphatic potential, the acquisition of big-conductance potassium channels (BK), and the onset of acoustic hearing. IHCs cultured in-vitro without endolymphatic potential (EP) do not grow, do not express BK, and do not experience nuclear movement. IHCs cultured in high K+ solutions (to simulate EP) grow but do not experience nuclear movement or acquire BK channels. CONCLUSION Nuclear migration at the onset of hearing is a key step in the morphological maturation of IHCs. Whether this plays a role in functional maturation remains to be explored.
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12
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Cohen R, Taiber S, Loza O, Kasirer S, Woland S, Sprinzak D. Precise alternating cellular pattern in the inner ear by coordinated hopping intercalations and delaminations. SCIENCE ADVANCES 2023; 9:eadd2157. [PMID: 36812313 DOI: 10.1126/sciadv.add2157] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 12/19/2022] [Indexed: 06/18/2023]
Abstract
The mammalian hearing organ, the organ of Corti, is one of the most organized tissues in mammals. It contains a precisely positioned array of alternating sensory hair cells (HCs) and nonsensory supporting cells. How such precise alternating patterns emerge during embryonic development is not well understood. Here, we combine live imaging of mouse inner ear explants with hybrid mechano-regulatory models to identify the processes that underlie the formation of a single row of inner hair cells (IHCs). First, we identify a previously unobserved morphological transition, termed "hopping intercalation," that allows cells differentiating toward IHC fate to "hop" under the apical plane into their final position. Second, we show that out-of-row cells with low levels of the HC marker Atoh1 delaminate. Last, we show that differential adhesion between cell types contributes to straightening of the IHC row. Our results support a mechanism for precise patterning based on coordination between signaling and mechanical forces that is likely relevant for many developmental processes.
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Affiliation(s)
- Roie Cohen
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
- Raymond and Beverly Sackler School of Physics and Astronomy, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Shahar Taiber
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Olga Loza
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Shahar Kasirer
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
- Raymond and Beverly Sackler School of Physics and Astronomy, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Shiran Woland
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - David Sprinzak
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
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13
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Stepwise fate conversion of supporting cells to sensory hair cells in the chick auditory epithelium. iScience 2023; 26:106046. [PMID: 36818302 PMCID: PMC9932131 DOI: 10.1016/j.isci.2023.106046] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 12/17/2022] [Accepted: 01/20/2023] [Indexed: 01/26/2023] Open
Abstract
In contrast to mammals, the avian cochlea, specifically the basilar papilla, can regenerate sensory hair cells, which involves fate conversion of supporting cells to hair cells. To determine the mechanisms for converting supporting cells to hair cells, we used single-cell RNA sequencing during hair cell regeneration in explant cultures of chick basilar papillae. We identified dynamic changes in the gene expression of supporting cells, and the pseudotime trajectory analysis demonstrated the stepwise fate conversion from supporting cells to hair cells. Initially, supporting cell identity was erased and transition to the precursor state occurred. A subsequent gain in hair cell identity progressed together with downregulation of precursor-state genes. Transforming growth factor β receptor 1-mediated signaling was involved in induction of the initial step, and its inhibition resulted in suppression of hair cell regeneration. Our data provide new insights for understanding fate conversion from supporting cells to hair cells in avian basilar papillae.
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14
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Wang Q, Wu J, Yang J, Huang S, Yuan Y, Dai P. Two SOX11 variants cause Coffin-Siris syndrome with a new feature of sensorineural hearing loss. Am J Med Genet A 2023; 191:183-189. [PMID: 36369738 PMCID: PMC10100107 DOI: 10.1002/ajmg.a.63011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 08/24/2022] [Accepted: 09/22/2022] [Indexed: 11/13/2022]
Abstract
Coffin-Siris syndrome (CSS, OMIM#135900) is a rare congenital disorder associated with neurodevelopmental and dysmorphic features. The primary cause of CSS is pathogenic variants in any of 9 BAF chromatin-remodeling complex encoding genes or the genes SOX11 and PHF6. Herein, we performed whole-exome sequencing (WES) and a series of analyses of growth-related, auditory, and radiological findings in two probands with syndromic sensorineural hearing loss and inner ear malformations who exhibited distinctive facial features, intellectual disability, growth retardation, and fifth finger malformation. Two de novo variants in the SOX11 gene (c.148A>C:p.Lys50Asn; c.811_814del:p.Asn271Serfs*10) were detected in these probands and were identified as pathogenic variants as per ACMG guidelines. These probands were diagnosed as having CSS based upon clinical and genetic findings. This is the first report of CSS caused by variants in SOX11 gene in Chinese individuals. Deleterious SOX11 variants can result in sensorineural hearing loss with inner ear malformation, potentially extending the array of phenotypes associated with these pathogenic variants. We suggest that both genetic and clinical findings be considered when diagnosing syndromic hearing loss.
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Affiliation(s)
- Qiuquan Wang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of hearing loss Prevention and Treatment, Beijing, China
| | - Jie Wu
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of hearing loss Prevention and Treatment, Beijing, China
| | - Jinyuan Yang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of hearing loss Prevention and Treatment, Beijing, China
| | - Shasha Huang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of hearing loss Prevention and Treatment, Beijing, China
| | - Yongyi Yuan
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of hearing loss Prevention and Treatment, Beijing, China
| | - Pu Dai
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,State Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of hearing loss Prevention and Treatment, Beijing, China
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15
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Chen J, Gao D, Sun L, Yang J. Kölliker’s organ-supporting cells and cochlear auditory development. Front Mol Neurosci 2022; 15:1031989. [PMID: 36304996 PMCID: PMC9592740 DOI: 10.3389/fnmol.2022.1031989] [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: 08/30/2022] [Accepted: 09/23/2022] [Indexed: 11/21/2022] Open
Abstract
The Kölliker’s organ is a transient cellular cluster structure in the development of the mammalian cochlea. It gradually degenerates from embryonic columnar cells to cuboidal cells in the internal sulcus at postnatal day 12 (P12)–P14, with the cochlea maturing when the degeneration of supporting cells in the Kölliker’s organ is complete, which is distinct from humans because it disappears at birth already. The supporting cells in the Kölliker’s organ play a key role during this critical period of auditory development. Spontaneous release of ATP induces an increase in intracellular Ca2+ levels in inner hair cells in a paracrine form via intercellular gap junction protein hemichannels. The Ca2+ further induces the release of the neurotransmitter glutamate from the synaptic vesicles of the inner hair cells, which subsequently excite afferent nerve fibers. In this way, the supporting cells in the Kölliker’s organ transmit temporal and spatial information relevant to cochlear development to the hair cells, promoting fine-tuned connections at the synapses in the auditory pathway, thus facilitating cochlear maturation and auditory acquisition. The Kölliker’s organ plays a crucial role in such a scenario. In this article, we review the morphological changes, biological functions, degeneration, possible trans-differentiation of cochlear hair cells, and potential molecular mechanisms of supporting cells in the Kölliker’s organ during the auditory development in mammals, as well as future research perspectives.
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Affiliation(s)
- Jianyong Chen
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Institute of Ear Science, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Otolaryngology and Translational Medicine, Shanghai, China
| | - Dekun Gao
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Institute of Ear Science, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Otolaryngology and Translational Medicine, Shanghai, China
| | - Lianhua Sun
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Institute of Ear Science, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Otolaryngology and Translational Medicine, Shanghai, China
- *Correspondence: Lianhua Sun Jun Yang
| | - Jun Yang
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
- Institute of Ear Science, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Otolaryngology and Translational Medicine, Shanghai, China
- *Correspondence: Lianhua Sun Jun Yang
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16
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Ebeid M, Barnas K, Zhang H, Yaghmour A, Noreikaite G, Bjork BC. PRDM16 expression and function in mammalian cochlear development. Dev Dyn 2022; 251:1666-1683. [PMID: 35451126 PMCID: PMC9790675 DOI: 10.1002/dvdy.480] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/08/2022] [Accepted: 04/09/2022] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND PR domain containing 16 (PRDM16) is a key transcriptional regulator in the development of craniofacial, adipose, and neural tissues. Our lab identified PRDM16 expression in the epithelial cells of the Kölliker's organ (KO) that starts at ~E13.5 and is maintained until KO disappearance. A transgenic mouse model that carries a gene trap null allele of Prdm16 (Prdm16cGT ) was used to characterize the impact of Prdm16 loss on cochlear development. RESULTS At P0 Prdm16cGT null cochlea exhibited hypoplastic KO, shortened cochlear duct, increased density of hair cells (HCs) and supporting cells (SCs) in the apical turn as well as multiple isolated ectopic HCs within the KO domain. KO epithelial cells proliferation rate was reduced in the apical turn of the developing Prdm16cGT null cochlea vs controls. Bulk RNA sequencing of cochlear duct cells at E14.5 followed by quantitative real time PCR and mRNA Fluorescence in-situ hybridization (FISH) validation identified differentially expressed genes in Prdm16cGT null vs littermate control cochleae. Upregulated genes at E14.5 included Fgf20, as well as several Notch pathway genes (Lfng, Hes1, and Jag1). CONCLUSIONS This study characterizes Prdm16 expression during cochlear development and establishes its requirement for KO development.
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Affiliation(s)
- Michael Ebeid
- College of Graduate Studies, Midwestern UniversityDowners GroveIllinoisUSA,Department of AnatomyMidwestern UniversityDowners GroveIllinoisUSA,Chicago College of Osteopathic MedicineMidwestern UniversityDowners GroveIllinoisUSA
| | - Kathy Barnas
- Biomedical Sciences ProgramMidwestern UniversityDowners GroveIllinoisUSA
| | - Hongji Zhang
- Department of AnatomyMidwestern UniversityDowners GroveIllinoisUSA
| | - Amal Yaghmour
- Biomedical Sciences ProgramMidwestern UniversityDowners GroveIllinoisUSA
| | - Gabriele Noreikaite
- Chicago College of Osteopathic MedicineMidwestern UniversityDowners GroveIllinoisUSA
| | - Bryan C. Bjork
- College of Graduate Studies, Midwestern UniversityDowners GroveIllinoisUSA
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17
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Abstract
Cochlear hair cells (HCs) in the inner ear are responsible for sound detection. For HC fate specification, the master transcription factor Atoh1 is both necessary and sufficient. Atoh1 expression is dynamic and tightly regulated during development, but the cis-regulatory elements mediating this regulation remain unresolved. Unexpectedly, we found that deleting the only recognized Atoh1 enhancer, defined here as Eh1, failed to impair HC development. By using the assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq), we discovered two additional Atoh1 enhancers: Eh2 and Eh3. Notably, Eh2 deletion was sufficient for impairing HC development, and concurrent deletion of Eh1 and Eh2 or all three enhancers resulted in nearly complete absence of HCs. Lastly, we showed that Atoh1 binds to all three enhancers, consistent with its autoregulatory function. Our findings reveal that the cooperative action of three distinct enhancers underpins effective Atoh1 regulation during HC development, indicating potential therapeutic approaches for HC regeneration.
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18
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Petitpré C, Faure L, Uhl P, Fontanet P, Filova I, Pavlinkova G, Adameyko I, Hadjab S, Lallemend F. Single-cell RNA-sequencing analysis of the developing mouse inner ear identifies molecular logic of auditory neuron diversification. Nat Commun 2022; 13:3878. [PMID: 35790771 PMCID: PMC9256748 DOI: 10.1038/s41467-022-31580-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 06/21/2022] [Indexed: 11/08/2022] Open
Abstract
Different types of spiral ganglion neurons (SGNs) are essential for auditory perception by transmitting complex auditory information from hair cells (HCs) to the brain. Here, we use deep, single cell transcriptomics to study the molecular mechanisms that govern their identity and organization in mice. We identify a core set of temporally patterned genes and gene regulatory networks that may contribute to the diversification of SGNs through sequential binary decisions and demonstrate a role for NEUROD1 in driving specification of a Ic-SGN phenotype. We also find that each trajectory of the decision tree is defined by initial co-expression of alternative subtype molecular controls followed by gradual shifts toward cell fate resolution. Finally, analysis of both developing SGN and HC types reveals cell-cell signaling potentially playing a role in the differentiation of SGNs. Our results indicate that SGN identities are drafted prior to birth and reveal molecular principles that shape their differentiation and will facilitate studies of their development, physiology, and dysfunction.
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Affiliation(s)
- Charles Petitpré
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Louis Faure
- Department of Neuroimmunology, Center for Brain Research, Medical University Vienna, 1090, Vienna, Austria
| | - Phoebe Uhl
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Paula Fontanet
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Iva Filova
- Institute of Biotechnology CAS, 25250, Vestec, Czech Republic
| | | | - Igor Adameyko
- Department of Neuroimmunology, Center for Brain Research, Medical University Vienna, 1090, Vienna, Austria
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Saida Hadjab
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
| | - Francois Lallemend
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
- Ming-Wai Lau Centre for Reparative Medicine, Stockholm Node, Karolinska Institutet, Stockholm, Sweden.
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19
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Kelley MW. Cochlear Development; New Tools and Approaches. Front Cell Dev Biol 2022; 10:884240. [PMID: 35813214 PMCID: PMC9260282 DOI: 10.3389/fcell.2022.884240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 05/19/2022] [Indexed: 12/21/2022] Open
Abstract
The sensory epithelium of the mammalian cochlea, the organ of Corti, is comprised of at least seven unique cell types including two functionally distinct types of mechanosensory hair cells. All of the cell types within the organ of Corti are believed to develop from a population of precursor cells referred to as prosensory cells. Results from previous studies have begun to identify the developmental processes, lineage restrictions and signaling networks that mediate the specification of many of these cell types, however, the small size of the organ and the limited number of each cell type has hampered progress. Recent technical advances, in particular relating to the ability to capture and characterize gene expression at the single cell level, have opened new avenues for understanding cellular specification in the organ of Corti. This review will cover our current understanding of cellular specification in the cochlea, discuss the most commonly used methods for single cell RNA sequencing and describe how results from a recent study using single cell sequencing provided new insights regarding cellular specification.
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20
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Lee MP, Waldhaus J. In vitro and in vivo models: What have we learnt about inner ear regeneration and treatment for hearing loss? Mol Cell Neurosci 2022; 120:103736. [PMID: 35577314 PMCID: PMC9551661 DOI: 10.1016/j.mcn.2022.103736] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 04/29/2022] [Accepted: 05/10/2022] [Indexed: 01/07/2023] Open
Abstract
The sensory cells of the inner ear, called hair cells, do not regenerate spontaneously and therefore, hair cell loss and subsequent hearing loss are permanent in humans. Conversely, functional hair cell regeneration can be observed in non-mammalian vertebrate species like birds and fish. Also, during postnatal development in mice, limited regenerative capacity and the potential to isolate stem cells were reported. Together, these findings spurred the interest of current research aiming to investigate the endogenous regenerative potential in mammals. In this review, we summarize current in vitro based approaches and briefly introduce different in vivo model organisms utilized to study hair cell regeneration. Furthermore, we present an overview of the findings that were made synergistically using both, the in vitro and in vivo based tools.
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Affiliation(s)
- Mary P Lee
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Joerg Waldhaus
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI 48109, USA.
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21
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GFI1 regulates hair cell differentiation by acting as an off-DNA transcriptional co-activator of ATOH1, and a DNA-binding repressor. Sci Rep 2022; 12:7793. [PMID: 35551236 PMCID: PMC9098437 DOI: 10.1038/s41598-022-11931-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 05/03/2022] [Indexed: 11/08/2022] Open
Abstract
GFI1 is a zinc finger transcription factor that is necessary for the differentiation and survival of hair cells in the cochlea. Deletion of Gfi1 in mice significantly reduces the expression of hundreds of hair cell genes: this is a surprising result, as GFI1 normally acts as a transcriptional repressor by recruiting histone demethylases and methyltransferases to its targets. To understand the mechanisms by which GFI1 promotes hair cell differentiation, we used CUT&RUN to identify the direct targets of GFI1 and ATOH1 in hair cells. We found that GFI1 regulates hair cell differentiation in two distinct ways—first, GFI1 and ATOH1 can bind to the same regulatory elements in hair cell genes, but while ATOH1 directly binds its target DNA motifs in many of these regions, GFI1 does not. Instead, it appears to enhance ATOH1’s transcriptional activity by acting as part of a complex in which it does not directly bind DNA. Second, GFI1 can act in its more typical role as a direct, DNA-binding transcriptional repressor in hair cells; here it represses non-hair cell genes, including many neuronal genes. Together, our results illuminate the function of GFI1 in hair cell development and hair cell reprogramming strategies.
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22
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Renauld JM, Khan V, Basch ML. Intermediate Cells of Dual Embryonic Origin Follow a Basal to Apical Gradient of Ingression Into the Lateral Wall of the Cochlea. Front Cell Dev Biol 2022; 10:867153. [PMID: 35372344 PMCID: PMC8964366 DOI: 10.3389/fcell.2022.867153] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 02/22/2022] [Indexed: 01/20/2023] Open
Abstract
Intermediate cells of the stria vascularis are neural crest derived melanocytes. They are essential for the establishment of the endocochlear potential in the inner ear, which allows mechanosensory hair cells to transduce sound into nerve impulses. Despite their importance for normal hearing, how these cells develop and migrate to their position in the lateral wall of the cochlea has not been studied. We find that as early as E10.5 some Schwann cell precursors in the VIIIth ganglion begin to express melanocyte specific markers while neural crest derived melanoblasts migrate into the otic vesicle. Intermediate cells of both melanoblast and Schwann cell precursor origin ingress into the lateral wall of the cochlea starting at around E15.5 following a basal to apical gradient during embryonic development, and continue to proliferate postnatally.
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Affiliation(s)
- Justine M Renauld
- Department of Otolaryngology, Head and Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Vibhuti Khan
- Department of Otolaryngology, Head and Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Martín L Basch
- Department of Otolaryngology, Head and Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, OH, United States.,Department of Genetics and Genome Sciences, Case Western Reserve School of Medicine, Cleveland, OH, United States.,Department of Biology, Case Western Reserve University, Cleveland, OH, United States.,Department of Otolaryngology, Head and Neck Surgery, University Hospitals, Cleveland, OH, United States
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23
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Single-cell transcriptomic landscapes of the otic neuronal lineage at multiple early embryonic ages. Cell Rep 2022; 38:110542. [PMID: 35320729 DOI: 10.1016/j.celrep.2022.110542] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 12/03/2021] [Accepted: 02/25/2022] [Indexed: 11/20/2022] Open
Abstract
Inner ear vestibular and spiral ganglion neurons (VGNs and SGNs) are known to play pivotal roles in balance control and sound detection. However, the molecular mechanisms underlying otic neurogenesis at early embryonic ages have remained unclear. Here, we use single-cell RNA sequencing to reveal the transcriptomes of mouse otic tissues at three embryonic ages, embryonic day 9.5 (E9.5), E11.5, and E13.5, covering proliferating and undifferentiated otic neuroblasts and differentiating VGNs and SGNs. We validate the high quality of our studies by using multiple assays, including genetic fate mapping analysis, and we uncover several genes upregulated in neuroblasts or differentiating VGNs and SGNs, such as Shox2, Myt1, Casz1, and Sall3. Notably, our findings suggest a general cascaded differentiation trajectory during early otic neurogenesis. The comprehensive understanding of early otic neurogenesis provided by our study holds critical implications for both basic and translational research.
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24
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Single-cell transcriptome analysis reveals three sequential phases of gene expression during zebrafish sensory hair cell regeneration. Dev Cell 2022; 57:799-819.e6. [PMID: 35316618 PMCID: PMC9188816 DOI: 10.1016/j.devcel.2022.03.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 11/19/2021] [Accepted: 02/28/2022] [Indexed: 12/20/2022]
Abstract
Loss of sensory hair cells (HCs) in the mammalian inner ear leads to permanent hearing and vestibular defects, whereas loss of HCs in zebrafish results in their regeneration. We used single-cell RNA sequencing (scRNA-seq) to characterize the transcriptional dynamics of HC regeneration in zebrafish at unprecedented spatiotemporal resolution. We uncovered three sequentially activated modules: first, an injury/inflammatory response and downregulation of progenitor cell maintenance genes within minutes after HC loss; second, the transient activation of regeneration-specific genes; and third, a robust re-activation of developmental gene programs, including HC specification, cell-cycle activation, ribosome biogenesis, and a metabolic switch to oxidative phosphorylation. The results are relevant not only for our understanding of HC regeneration and how we might be able to trigger it in mammals but also for regenerative processes in general. The data are searchable and publicly accessible via a web-based interface.
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25
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Sun Y, Zhang Y, Zhang D, Wang G, Song L, Liu Z. In vivo CRISPR-Cas9-mediated DNA chop identifies a cochlear outer hair cell-specific enhancer. FASEB J 2022; 36:e22233. [PMID: 35225354 DOI: 10.1096/fj.202100421rr] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 02/06/2022] [Accepted: 02/14/2022] [Indexed: 01/18/2023]
Abstract
Cochlear outer hair cells (OHCs) are essential for hearing. A short, OHC-specific enhancer is necessary but not yet available for gene therapeutic applications in OHC damage. Such damage is a major cause of deafness. Prestin is a motor protein exclusively expressed in OHCs. We hypothesized that the cis-regulatory DNA fragment deletion of Slc26a5 would affect its expression. We tested this hypothesis by conducting CRISPR/Cas9-mediated large DNA fragment deletion of mouse Slc26a5 intron regions. First, starting from a ~13 kbp fragment, step-by-step, we narrowed down the sequence to a 1.4 kbp segment. By deleting either a 13 kbp or 1.4 kbp fragment, we observed delayed Prestin expression. Second, we showed that 1.4 kbp was an OHC-specific enhancer because enhanced green fluorescent protein (EGFP) was highly and specifically expressed in OHCs in a transgenic mouse where EGFP was driven by the 1.4 kbp segment. More importantly, specific EGFP was also driven by its homologous 398 bp fragment in human Slc26a5. This suggests that the enhancer is likely to be evolutionarily conserved across different species.
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Affiliation(s)
- Yuwei Sun
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yu Zhang
- Department of Otolaryngology-Head and Neck Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Di Zhang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Guangqin Wang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Lei Song
- Department of Otolaryngology-Head and Neck Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Ear Institute, Shanghai Jiao Tong University School of Medicine, 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.,University of Chinese Academy of Sciences, Beijing, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai, China
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26
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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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27
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Ishii M, Tateya T, Matsuda M, Hirashima T. Stalling interkinetic nuclear migration in curved pseudostratified epithelium of developing cochlea. ROYAL SOCIETY OPEN SCIENCE 2021; 8:211024. [PMID: 34909216 PMCID: PMC8652271 DOI: 10.1098/rsos.211024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 11/05/2021] [Indexed: 05/15/2023]
Abstract
The bending of epithelial tubes is a fundamental process in organ morphogenesis, driven by various multicellular behaviours. The cochlea in the mammalian inner ear is a representative example of spiral tissue architecture where the continuous bending of the duct is a fundamental component of its morphogenetic process. Although the cochlear duct morphogenesis has been studied by genetic approaches extensively, it is still unclear how the cochlear duct morphology is physically formed. Here, we report that nuclear behaviour changes are associated with the curvature of the pseudostratified epithelium during murine cochlear development. Two-photon live-cell imaging reveals that the nuclei shuttle between the luminal and basal edges of the cell is in phase with cell-cycle progression, known as interkinetic nuclear migration, in the flat region of the pseudostratified epithelium. However, the nuclei become stationary on the luminal side following mitosis in the curved region. Mathematical modelling together with perturbation experiments shows that this nuclear stalling facilitates luminal-basal differential growth within the epithelium, suggesting that the nuclear stalling would contribute to the bending of the pseudostratified epithelium during the cochlear duct development. The findings suggest a possible scenario of differential growth which sculpts the tissue shape, driven by collective nuclear dynamics.
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Affiliation(s)
- Mamoru Ishii
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Tomoko Tateya
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
- Department of Speech and Hearing Sciences and Disorders, Faculty of Health and Medical Sciences, Kyoto University of Advanced Science, Kyoto, Japan
| | - Michiyuki Matsuda
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- Department of Pathology and Biology of Diseases, Graduate School of Medicine, Kyoto University, Kyoto, Japan
- Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto, Japan
| | - Tsuyoshi Hirashima
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
- The Hakubi Center, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
- Japan Science and Technology Agency, PRESTO, Kawaguchi, Japan
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28
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Ahmed M, Moon R, Prajapati RS, James E, Basson MA, Streit A. The chromatin remodelling factor Chd7 protects auditory neurons and sensory hair cells from stress-induced degeneration. Commun Biol 2021; 4:1260. [PMID: 34732824 PMCID: PMC8566505 DOI: 10.1038/s42003-021-02788-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 10/08/2021] [Indexed: 11/08/2022] Open
Abstract
Neurons and sensory cells are particularly vulnerable to oxidative stress due to their high oxygen demand during stimulus perception and transmission. The mechanisms that protect them from stress-induced death and degeneration remain elusive. Here we show that embryonic deletion of the chromodomain helicase DNA-binding protein 7 (CHD7) in auditory neurons or hair cells leads to sensorineural hearing loss due to postnatal degeneration of both cell types. Mechanistically, we demonstrate that CHD7 controls the expression of major stress pathway components. In its absence, hair cells are hypersensitive, dying rapidly after brief exposure to stress inducers, suggesting that sound at the onset of hearing triggers their degeneration. In humans, CHD7 haploinsufficiency causes CHARGE syndrome, a disorder affecting multiple organs including the ear. Our findings suggest that CHD7 mutations cause developmentally silent phenotypes that predispose cells to postnatal degeneration due to a failure of protective mechanisms.
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Affiliation(s)
- Mohi Ahmed
- Centre for Craniofacial and Regenerative Biology, Floor 27 Tower Wing, Guy's Hospital, King's College London, London, SE1 9RT, UK.
| | - Ruth Moon
- Centre for Craniofacial and Regenerative Biology, Floor 27 Tower Wing, Guy's Hospital, King's College London, London, SE1 9RT, UK
| | - Ravindra Singh Prajapati
- Centre for Craniofacial and Regenerative Biology, Floor 27 Tower Wing, Guy's Hospital, King's College London, London, SE1 9RT, UK
- Leukaemia and Stem Cell Biology Group, School of Cancer and Pharmaceutical Sciences, King's College London, London, SE5 9NU, UK
| | - Elysia James
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, SE1 1UL, UK
| | - M Albert Basson
- Centre for Craniofacial and Regenerative Biology, Floor 27 Tower Wing, Guy's Hospital, King's College London, London, SE1 9RT, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, SE1 1UL, UK
| | - Andrea Streit
- Centre for Craniofacial and Regenerative Biology, Floor 27 Tower Wing, Guy's Hospital, King's College London, London, SE1 9RT, UK.
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29
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Riley BB. Comparative assessment of Fgf's diverse roles in inner ear development: A zebrafish perspective. Dev Dyn 2021; 250:1524-1551. [PMID: 33830554 DOI: 10.1002/dvdy.343] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/26/2021] [Accepted: 03/26/2021] [Indexed: 01/21/2023] Open
Abstract
Progress in understanding mechanisms of inner ear development has been remarkably rapid in recent years. The research community has benefited from the availability of several diverse model organisms, including zebrafish, chick, and mouse. The complexity of the inner ear has proven to be a challenge, and the complexity of the mammalian cochlea in particular has been the subject of intense scrutiny. Zebrafish lack a cochlea and exhibit a number of other differences from amniote species, hence they are sometimes seen as less relevant for inner ear studies. However, accumulating evidence shows that underlying cellular and molecular mechanisms are often highly conserved. As a case in point, consideration of the diverse functions of Fgf and its downstream effectors reveals many similarities between vertebrate species, allowing meaningful comparisons the can benefit the entire research community. In this review, I will discuss mechanisms by which Fgf controls key events in early otic development in zebrafish and provide direct comparisons with chick and mouse.
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Affiliation(s)
- Bruce B Riley
- Biology Department, Texas A&M University, College Station, Texas, USA
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30
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Almasoudi SH, Schlosser G. Otic Neurogenesis in Xenopus laevis: Proliferation, Differentiation, and the Role of Eya1. Front Neuroanat 2021; 15:722374. [PMID: 34616280 PMCID: PMC8488300 DOI: 10.3389/fnana.2021.722374] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/27/2021] [Indexed: 11/15/2022] Open
Abstract
Using immunostaining and confocal microscopy, we here provide the first detailed description of otic neurogenesis in Xenopus laevis. We show that the otic vesicle comprises a pseudostratified epithelium with apicobasal polarity (apical enrichment of Par3, aPKC, phosphorylated Myosin light chain, N-cadherin) and interkinetic nuclear migration (apical localization of mitotic, pH3-positive cells). A Sox3-immunopositive neurosensory area in the ventromedial otic vesicle gives rise to neuroblasts, which delaminate through breaches in the basal lamina between stages 26/27 and 39. Delaminated cells congregate to form the vestibulocochlear ganglion, whose peripheral cells continue to proliferate (as judged by EdU incorporation), while central cells differentiate into Islet1/2-immunopositive neurons from stage 29 on and send out neurites at stage 31. The central part of the neurosensory area retains Sox3 but stops proliferating from stage 33, forming the first sensory areas (utricular/saccular maculae). The phosphatase and transcriptional coactivator Eya1 has previously been shown to play a central role for otic neurogenesis but the underlying mechanism is poorly understood. Using an antibody specifically raised against Xenopus Eya1, we characterize the subcellular localization of Eya1 proteins, their levels of expression as well as their distribution in relation to progenitor and neuronal differentiation markers during otic neurogenesis. We show that Eya1 protein localizes to both nuclei and cytoplasm in the otic epithelium, with levels of nuclear Eya1 declining in differentiating (Islet1/2+) vestibulocochlear ganglion neurons and in the developing sensory areas. Morpholino-based knockdown of Eya1 leads to reduction of proliferating, Sox3- and Islet1/2-immunopositive cells, redistribution of cell polarity proteins and loss of N-cadherin suggesting that Eya1 is required for maintenance of epithelial cells with apicobasal polarity, progenitor proliferation and neuronal differentiation during otic neurogenesis.
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Affiliation(s)
| | - Gerhard Schlosser
- School of Natural Sciences, National University of Galway, Galway, Ireland
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31
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Kwan KY, White PM. Understanding the differentiation and epigenetics of cochlear sensory progenitors in pursuit of regeneration. Curr Opin Otolaryngol Head Neck Surg 2021; 29:366-372. [PMID: 34374667 PMCID: PMC8452321 DOI: 10.1097/moo.0000000000000741] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE OF REVIEW Sensory hair cells (HCs) of the inner ear are responsible for our ability to hear and balance. Loss of these cells results in hearing loss. Stem cell replacement and in situ regeneration have the potential to replace lost HCs. Newly discovered contributions of transcription factor regulatory networks and epigenetic mechanisms in regulating HC differentiation and regeneration are placed into context of the literature. RECENT FINDINGS A wealth of new data has helped to define cochlear sensory progenitors in their developmental trajectories. This includes transcription factor networks, epigenetic manipulations, and cochlear HC subtype specification. SUMMARY Understanding how sensory progenitors differ and how HC subtypes arise will substantially inform efforts in hearing restoration.
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Affiliation(s)
- Kelvin Y. Kwan
- Department of Cell Biology & Neuroscience, Rutgers University, Piscataway, New Jersey
| | - Patricia M. White
- Department of Neuroscience, Ernest J. Del Monte Institute of Neuroscience, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
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32
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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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33
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Norrie disease protein is essential for cochlear hair cell maturation. Proc Natl Acad Sci U S A 2021; 118:2106369118. [PMID: 34544869 DOI: 10.1073/pnas.2106369118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2021] [Indexed: 11/18/2022] Open
Abstract
Mutations in the gene for Norrie disease protein (Ndp) cause syndromic deafness and blindness. We show here that cochlear function in an Ndp knockout mouse deteriorated with age: At P3-P4, hair cells (HCs) showed progressive loss of Pou4f3 and Gfi1, key transcription factors for HC maturation, and Myo7a, a specialized myosin required for normal function of HC stereocilia. Loss of expression of these genes correlated to increasing HC loss and profound hearing loss by 2 mo. We show that overexpression of the Ndp gene in neonatal supporting cells or, remarkably, up-regulation of canonical Wnt signaling in HCs rescued HCs and cochlear function. We conclude that Ndp secreted from supporting cells orchestrates a transcriptional network for the maintenance and survival of HCs and that increasing the level of β-catenin, the intracellular effector of Wnt signaling, is sufficient to replace the functional requirement for Ndp in the cochlea.
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34
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Liu Q, Zhang L, Zhu MS, Wan G. High-throughput screening on cochlear organoids identifies VEGFR-MEK-TGFB1 signaling promoting hair cell reprogramming. Stem Cell Reports 2021; 16:2257-2273. [PMID: 34525385 PMCID: PMC8452601 DOI: 10.1016/j.stemcr.2021.08.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 08/17/2021] [Accepted: 08/17/2021] [Indexed: 01/06/2023] Open
Abstract
Hair cell degeneration is a major cause of sensorineural hearing loss. Hair cells in mammalian cochlea do not spontaneously regenerate, posing a great challenge for restoration of hearing. Here, we establish a robust, high-throughput cochlear organoid platform that facilitates 3D expansion of cochlear progenitor cells and differentiation of hair cells in a temporally regulated manner. High-throughput screening of the FDA-approved drug library identified regorafenib, a VEGFR inhibitor, as a potent small molecule for hair cell differentiation. Regorafenib also promotes reprogramming and maturation of hair cells in both normal and neomycin-damaged cochlear explants. Mechanistically, inhibition of VEGFR suppresses TGFB1 expression via the MEK pathway and TGFB1 downregulation directly mediates the effect of regorafenib on hair cell reprogramming. Our study not only demonstrates the power of a cochlear organoid platform in high-throughput analyses of hair cell physiology but also highlights VEGFR-MEK-TGFB1 signaling crosstalk as a potential target for hair cell regeneration and hearing restoration. Cochlear organoids can be derived from both LGR5+ and LGR5– supporting cells HTS using cochlear organoids identifies regorafenib for hair cell differentiation Regorafenib promotes hair cell reprogramming and maturation in cochlear explants Regorafenib acts via a NOTCH-independent and VEGFR-MEK-TGFB1-dependent mechanism
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Affiliation(s)
- Qing Liu
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology-Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing 210032, China
| | - Linqing Zhang
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology-Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing 210032, China
| | - Min-Sheng Zhu
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology-Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing 210032, China
| | - Guoqiang Wan
- MOE Key Laboratory of Model Animal for Disease Study, Department of Otorhinolaryngology-Head and Neck Surgery, The Affiliated Drum Tower Hospital of Medical School, Model Animal Research Center of Medical School, Nanjing University, Nanjing 210032, China; Research Institute of Otolaryngology, No. 321 Zhongshan Road, 210008 Nanjing, China; Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing 210032, China; Institute for Brain Sciences, Nanjing University, Nanjing 210032, China.
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35
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Erni ST, Gill JC, Palaferri C, Fernandes G, Buri M, Lazarides K, Grandgirard D, Edge ASB, Leib SL, Roccio M. Hair Cell Generation in Cochlear Culture Models Mediated by Novel γ-Secretase Inhibitors. Front Cell Dev Biol 2021; 9:710159. [PMID: 34485296 PMCID: PMC8414802 DOI: 10.3389/fcell.2021.710159] [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: 05/15/2021] [Accepted: 07/26/2021] [Indexed: 12/30/2022] Open
Abstract
Sensorineural hearing loss is prevalent within society affecting the quality of life of 460 million worldwide. In the majority of cases, this is due to insult or degeneration of mechanosensory hair cells in the cochlea. In adult mammals, hair cell loss is irreversible as sensory cells are not replaced spontaneously. Genetic inhibition of Notch signaling had been shown to induce hair cell formation by transdifferentiation of supporting cells in young postnatal rodents and provided an impetus for targeting Notch pathway with small molecule inhibitors for hearing restoration. Here, the oto-regenerative potential of different γ-secretase inhibitors (GSIs) was evaluated in complementary assay models, including cell lines, organotypic cultures of the organ of Corti and cochlear organoids to characterize two novel GSIs (CPD3 and CPD8). GSI-treatment induced hair cell gene expression in all these models and was effective in increasing hair cell numbers, in particular outer hair cells, both in baseline conditions and in response to ototoxic damage. Hair cells were generated from transdifferentiation of supporting cells. Similar findings were obtained in cochlear organoid cultures, used for the first time to probe regeneration following sisomicin-induced damage. Finally, effective absorption of a novel GSI through the round window membrane and hair cell induction was attained in a whole cochlea culture model and in vivo pharmacokinetic comparisons of transtympanic delivery of GSIs and different vehicle formulations were successfully conducted in guinea pigs. This preclinical evaluation of targeting Notch signaling with novel GSIs illustrates methods of characterization for hearing restoration molecules, enabling translation to more complex animal studies and clinical research.
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Affiliation(s)
- Silvia T Erni
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - John C Gill
- Audion Therapeutics B.V., Amsterdam, Netherlands
| | - Carlotta Palaferri
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Gabriella Fernandes
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Michelle Buri
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | | | - Denis Grandgirard
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Albert S B Edge
- Massachusetts Eye and Ear, Boston, MA, United States.,Harvard Medical School, Boston, MA, United States.,Harvard Stem Cell Institute, Cambridge, MA, United States
| | - Stephen L Leib
- Neuroinfection Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Cluster for Regenerative Neuroscience, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Marta Roccio
- Cluster for Regenerative Neuroscience, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Laboratory of Inner Ear Research, Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland.,Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Zurich, Zurich, Switzerland.,Department of Otorhinolaryngology, University of Zurich, Zurich, Switzerland
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36
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Ajdari S, Saffari-Chaleshtori J, Pourteymourfard-Tabrizi Z, Ghasemi-Dehkordi P, Samani MG, Validi M, Kabiri H, Chaleshtori MH, Jami MS. Rare mutations in Atoh1 lead to hearing loss. GENE REPORTS 2021. [DOI: 10.1016/j.genrep.2021.101254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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37
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Tang Q, Xie MY, Zhang YL, Xue RY, Zhu XH, Yang H. Targeted deletion of Atoh8 results in severe hearing loss in mice. Genesis 2021; 59:e23442. [PMID: 34402594 PMCID: PMC9286369 DOI: 10.1002/dvg.23442] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 08/01/2021] [Accepted: 08/02/2021] [Indexed: 11/29/2022]
Abstract
Atoh8, also named Math6, is a bHLH gene reported to have important functions in the developing nervous system, pancreas and kidney. However, the expression pattern and function of Atoh8 in the inner ear are still unclear. To study the function of Atoh8 in the developing mouse inner ear, we performed targeted deletion of Atoh8 by intercrossing Atoh8lacZ/+ mice. We studied the expression pattern of Atoh8 in the inner ear and found interesting results that Atoh8‐null (Atoh8lacZ/lacZ) mice were viable but smaller than their littermates and they were severely hearing impaired, which was confirmed by hearing tests (ABR, DPOAE). We collected 129 viable newborns from 18 litters by crossing Atoh8lacZ/+ mice and found that the distributions of Atoh8lacZ/+, Atoh8lacZ/lacZ and wild type were very close to their expected Mendelian ratio by χ2 testing. However, no remarkable morphological changes in cochleae in mutant mice were detected under plastic sectioning and electron microscopy. No remarkable differences in the expression of Myosin6, Prestin, TrkC, GAD65, Tuj1, or Calretinin were detected between the mutant mice and the control mice. These findings indicate that Atoh8 plays an important role in the development of normal hearing, while further studies are required to elucidate its exact function in hearing.
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Affiliation(s)
- Qi Tang
- Department of Otolaryngology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Translational Medicine Center, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Meng-Yao Xie
- Department of Otolaryngology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Translational Medicine Center, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yong-Li Zhang
- Department of Otolaryngology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Translational Medicine Center, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Ruo-Yan Xue
- Department of Otolaryngology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Translational Medicine Center, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xiao-Hui Zhu
- Department of Otolaryngology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Translational Medicine Center, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Hua Yang
- Department of Otolaryngology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Translational Medicine Center, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Sun H, Wang T, Atkinson PJ, Billings SE, Dong W, Cheng AG. Gpr125 Marks Distinct Cochlear Cell Types and Is Dispensable for Cochlear Development and Hearing. Front Cell Dev Biol 2021; 9:690955. [PMID: 34395423 PMCID: PMC8355630 DOI: 10.3389/fcell.2021.690955] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 06/14/2021] [Indexed: 01/16/2023] Open
Abstract
The G protein-coupled receptor (GPR) family critically regulates development and homeostasis of multiple organs. As a member of the GPR adhesion family, Gpr125 (Adgra3) modulates Wnt/PCP signaling and convergent extension in developing zebrafish, but whether it is essential for cochlear development in mammals is unknown. Here, we examined the Gpr125 lacZ/+ knock-in mice and show that Gpr125 is dynamically expressed in the developing and mature cochleae. From embryonic day (E) 15.5 to postnatal day (P) 30, Gpr125-β-Gal is consistently expressed in the lesser epithelial ridge and its presumed progenies, the supporting cell subtypes Claudius cells and Hensen's cells. In contrast, Gpr125-β-Gal is expressed transiently in outer hair cells, epithelial cells in the lateral cochlear wall, interdental cells, and spiral ganglion neurons in the late embryonic and early postnatal cochlea. In situ hybridization for Gpr125 mRNA confirmed Gpr125 expression and validated loss of expression in Gpr125 lacZ/lacZ cochleae. Lastly, Gpr125 lacZ/+ and Gpr125 lacZ/ lacZ cochleae displayed no detectable loss or disorganization of either sensory or non-sensory cells in the embryonic and postnatal ages and exhibited normal auditory physiology. Together, our study reveals that Gpr125 is dynamically expressed in multiple cell types in the developing and mature cochlea and is dispensable for cochlear development and hearing.
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Affiliation(s)
- Haiying Sun
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Tian Wang
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Patrick J. Atkinson
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Sara E. Billings
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Wuxing Dong
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Alan G. Cheng
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
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Enhancer decommissioning imposes an epigenetic barrier to sensory hair cell regeneration. Dev Cell 2021; 56:2471-2485.e5. [PMID: 34331868 DOI: 10.1016/j.devcel.2021.07.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 06/24/2021] [Accepted: 07/08/2021] [Indexed: 01/02/2023]
Abstract
Adult mammalian tissues such as heart, brain, retina, and the sensory structures of the inner ear do not effectively regenerate, although a latent capacity for regeneration exists at embryonic and perinatal times. We explored the epigenetic basis for this latent regenerative potential in the mouse inner ear and its rapid loss during maturation. In perinatal supporting cells, whose fate is maintained by Notch-mediated lateral inhibition, the hair cell enhancer network is epigenetically primed (H3K4me1) but silenced (active H3K27 de-acetylation and trimethylation). Blocking Notch signaling during the perinatal period of plasticity rapidly eliminates epigenetic silencing and allows supporting cells to transdifferentiate into hair cells. Importantly, H3K4me1 priming of the hair cell enhancers in supporting cells is removed during the first post-natal week, coinciding with the loss of transdifferentiation potential. We hypothesize that enhancer decommissioning during cochlear maturation contributes to the failure of hair cell regeneration in the mature organ of Corti.
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POU4F3 pioneer activity enables ATOH1 to drive diverse mechanoreceptor differentiation through a feed-forward epigenetic mechanism. Proc Natl Acad Sci U S A 2021; 118:2105137118. [PMID: 34266958 DOI: 10.1073/pnas.2105137118] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During embryonic development, hierarchical cascades of transcription factors interact with lineage-specific chromatin structures to control the sequential steps in the differentiation of specialized cell types. While examples of transcription factor cascades have been well documented, the mechanisms underlying developmental changes in accessibility of cell type-specific enhancers remain poorly understood. Here, we show that the transcriptional "master regulator" ATOH1-which is necessary for the differentiation of two distinct mechanoreceptor cell types, hair cells in the inner ear and Merkel cells of the epidermis-is unable to access much of its target enhancer network in the progenitor populations of either cell type when it first appears, imposing a block to further differentiation. This block is overcome by a feed-forward mechanism in which ATOH1 first stimulates expression of POU4F3, which subsequently acts as a pioneer factor to provide access to closed ATOH1 enhancers, allowing hair cell and Merkel cell differentiation to proceed. Our analysis also indicates the presence of both shared and divergent ATOH1/POU4F3-dependent enhancer networks in hair cells and Merkel cells. These cells share a deep developmental lineage relationship, deriving from their common epidermal origin, and suggesting that this feed-forward mechanism preceded the evolutionary divergence of these very different mechanoreceptive cell types.
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Oya R, Tsukamoto O, Sato T, Kato H, Matsuoka K, Oshima K, Kamakura T, Ohta Y, Imai T, Takashima S, Inohara H. Phosphorylation of MYL12 by Myosin Light Chain Kinase Regulates Cellular Shape Changes in Cochlear Hair Cells. J Assoc Res Otolaryngol 2021; 22:425-441. [PMID: 33877471 PMCID: PMC8329122 DOI: 10.1007/s10162-021-00796-1] [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: 12/31/2020] [Accepted: 03/11/2021] [Indexed: 10/21/2022] Open
Abstract
The organ of Corti is an auditory organ located in the cochlea, comprising hair cells (HCs) and other supporting cells. Cellular shape changes of HCs are important for the development of auditory epithelia and hearing function. It was previously observed that HCs and inner sulcus cells (ISCs) demonstrate cellular shape changes similar to the apical constriction of the neural epithelia. Apical constriction is induced via actomyosin cable contraction in the apical junctional complex and necessary for the physiological function of the epithelium. Actomyosin cable contraction is mainly regulated by myosin regulatory light chain (MRLC) phosphorylation by myosin light chain kinase (MLCK). However, MRLC and MLCK isoforms expressed in HCs and ISCs are unknown. Hence, we investigated the expression patterns and roles of MRLCs and MLCKs in HCs. Droplet digital PCR revealed that HCs expressed MYL12A/B and MYL9, which are non-muscle MRLC and smooth muscle MLCK (smMLCK), respectively. Immunofluorescence staining throughout the organ of Corti demonstrated that only MYL12 was expressed in the apical portion of HCs, whereas MYL12 and MYL9 were expressed on ISCs. In addition, purified MYL12B was phosphorylated by smMLCK in vitro, and the harvested HCs contained phosphorylated MYL12. Furthermore, accompanied by the expansion of the cell area of outer HCs, MYL12 phosphorylation was reduced by ML-7, which is an inhibitor of smMLCK. In conclusion, MYL12 phosphorylation by smMLCK contributed to the apical constriction-like cellular shape change of HCs possibly relating to the development of auditory epithelia and hearing function.
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Affiliation(s)
- Ryohei Oya
- Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
- Department of Medical Biochemistry, Osaka University Graduate School of Medicine/Frontier Biosciences, Osaka, Japan
| | - Osamu Tsukamoto
- Department of Medical Biochemistry, Osaka University Graduate School of Medicine/Frontier Biosciences, Osaka, Japan
| | - Takashi Sato
- Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Hisakazu Kato
- Department of Medical Biochemistry, Osaka University Graduate School of Medicine/Frontier Biosciences, Osaka, Japan
| | - Ken Matsuoka
- Department of Medical Biochemistry, Osaka University Graduate School of Medicine/Frontier Biosciences, Osaka, Japan
| | - Kazuo Oshima
- Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Takefumi Kamakura
- Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Yumi Ohta
- Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Takao Imai
- Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Seiji Takashima
- Department of Medical Biochemistry, Osaka University Graduate School of Medicine/Frontier Biosciences, Osaka, Japan
| | - Hidenori Inohara
- Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
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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: 18] [Impact Index Per Article: 6.0] [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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Wang S, Lee MP, Jones S, Liu J, Waldhaus J. Mapping the regulatory landscape of auditory hair cells from single-cell multi-omics data. Genome Res 2021; 31:1885-1899. [PMID: 33837132 DOI: 10.1101/gr.271080.120] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 03/23/2021] [Indexed: 11/25/2022]
Abstract
Auditory hair cells transduce sound to the brain and in mammals these cells reside together with supporting cells in the sensory epithelium of the cochlea, called the organ of Corti. To establish the organ's delicate function during development and differentiation, spatiotemporal gene expression is strictly controlled by chromatin accessibility and cell type-specific transcription factors, jointly representing the regulatory landscape. Bulk-sequencing technology and cellular heterogeneity obscured investigations on the interplay between transcription factors and chromatin accessibility in inner ear development. To study the formation of the regulatory landscape in hair cells, we collected single-cell chromatin accessibility profiles accompanied by single-cell RNA data from genetically labeled murine hair cells and supporting cells after birth. Using an integrative approach, we predicted cell type-specific activating and repressing functions of developmental transcription factors. Furthermore, by integrating gene expression and chromatin accessibility datasets, we reconstructed gene regulatory networks. Then, using a comparative approach, 20 hair cell-specific activators and repressors, including putative downstream target genes, were identified. Clustering of target genes resolved groups of related transcription factors and was utilized to infer their developmental functions. Finally, the heterogeneity in the single-cell data allowed us to spatially reconstruct transcriptional as well as chromatin accessibility trajectories, indicating that gradual changes in the chromatin accessibility landscape were lagging behind the transcriptional identity of hair cells along the organ's longitudinal axis. Overall, this study provides a strategy to spatially reconstruct the formation of a lineage specific regulatory landscape using a single-cell multi-omics approach.
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Affiliation(s)
- Shuze Wang
- University of Michigan, Kresge Hearing Research Institute
| | - Mary P Lee
- University of Michigan, Kresge Hearing Research Institute
| | - Scott Jones
- University of Michigan, Kresge Hearing Research Institute
| | | | - Joerg Waldhaus
- University of Michigan, Kresge Hearing Research Institute;
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Different Neurogenic Potential in the Subnuclei of the Postnatal Rat Cochlear Nucleus. Stem Cells Int 2021; 2021:8871308. [PMID: 33880121 PMCID: PMC8046557 DOI: 10.1155/2021/8871308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 02/03/2021] [Accepted: 03/12/2021] [Indexed: 11/17/2022] Open
Abstract
In patients suffering from hearing loss, the reduced or absent neural input induces morphological changes in the cochlear nucleus (CN). Neural stem cells have recently been identified in this first auditory relay. Afferent nerve signals and their impact on the immanent neural stem and progenitor cells already impinge upon the survival of early postnatal cells within the CN. This auditory brainstem nucleus consists of three different subnuclei: the anteroventral cochlear nucleus (AVCN), the posteroventral cochlear nucleus (PVCN), and the dorsal cochlear nucleus (DCN). Since these subdivisions differ ontogenetically and physiologically, the question arose whether regional differences exist in the neurogenic niche. CN from postnatal day nine Sprague-Dawley rats were microscopically dissected into their subnuclei and cultivated in vitro as free-floating cell cultures and as whole-mount organ cultures. In addition to cell quantifications, immunocytological and immunohistological studies of the propagated cells and organ preparations were performed. The PVCN part showed the highest mitotic potential, while the AVCN and DCN had comparable activity. Specific stem cell markers and the ability to differentiate into cells of the neural lineage were detected in all three compartments. The present study shows that in all subnuclei of rat CN, there is a postnatal neural stem cell niche, which, however, differs significantly in its potential. The results can be explained by the origin from different regions in the rhombic lip, the species, and the various analysis techniques applied. In conclusion, the presented results provide further insight into the neurogenic potential of the CN, which may prove beneficial for the development of new regenerative strategies for hearing loss.
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45
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Wang G, Li C, He S, Liu Z. Mosaic CRISPR-stop enables rapid phenotyping of nonsense mutations in essential genes. Development 2021; 148:dev196899. [PMID: 33558388 DOI: 10.1242/dev.196899] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 01/29/2021] [Indexed: 12/25/2022]
Abstract
CRISPR-stop converts protein-coding sequences into stop codons, which, in the appropriate location, results in a null allele. CRISPR-stop induction in one-cell-stage zygotes generates Founder 0 (F0) mice that are homozygous mutants; this avoids mouse breeding and serves as a rapid screening approach for nonlethal genes. However, loss of function of 25% of mammalian genes causes early lethality. Here, we induced CRISPR-stop in one of the two blastomeres of the zygote, a method we name mosaic CRISPR-stop, to produce mosaic Atoh1 and Sox10 F0 mice; these mice not only survived longer than regular Atoh1/Sox10 knockout mice but also displayed their recognized cochlear phenotypes. Moreover, by using mosaic CRISPR-stop, we uncovered a previously unknown role of another lethal gene, Rbm24, in the survival of cochlear outer hair cells (OHCs), and we further validated the importance of Rbm24 in OHCs by using our Rbm24 conditional knockout model. Together, our results demonstrated that mosaic CRISPR-stop is reliable and rapid, and we believe this method will facilitate rapid genetic screening of developmentally lethal genes in the mouse inner ear and also in other organs.
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MESH Headings
- Animals
- Basic Helix-Loop-Helix Transcription Factors/deficiency
- Basic Helix-Loop-Helix Transcription Factors/genetics
- Blastomeres/cytology
- Blastomeres/metabolism
- CRISPR-Cas Systems/genetics
- Codon, Nonsense
- Codon, Terminator
- Genes, Essential/genetics
- Hair Cells, Auditory, Outer/cytology
- Hair Cells, Auditory, Outer/metabolism
- Mice
- Mice, Knockout
- RNA, Guide, CRISPR-Cas Systems/metabolism
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- SOXE Transcription Factors/deficiency
- SOXE Transcription Factors/genetics
- Zygote/cytology
- Zygote/metabolism
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Affiliation(s)
- Guangqin Wang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, 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 200031, China
| | - Shunji He
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, 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 200031, China
- Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
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46
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Webber JL, Clancy JC, Zhou Y, Yraola N, Homma K, García-Añoveros J. Axodendritic versus axosomatic cochlear efferent termination is determined by afferent type in a hierarchical logic of circuit formation. SCIENCE ADVANCES 2021; 7:7/4/eabd8637. [PMID: 33523928 PMCID: PMC7817091 DOI: 10.1126/sciadv.abd8637] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 12/03/2020] [Indexed: 05/09/2023]
Abstract
Hearing involves a stereotyped neural network communicating cochlea and brain. How this sensorineural circuit assembles is largely unknown. The cochlea houses two types of mechanosensory hair cells differing in function (sound transmission versus amplification) and location (inner versus outer compartments). Inner (IHCs) and outer hair cells (OHCs) are each innervated by a distinct pair of afferent and efferent neurons: IHCs are contacted by type I afferents receiving axodendritic efferent contacts; OHCs are contacted by type II afferents and axosomatically terminating efferents. Using an Insm1 mouse mutant with IHCs in the position of OHCs, we discover a hierarchical sequence of instructions in which first IHCs attract, and OHCs repel, type I afferents; second, type II afferents innervate hair cells not contacted by type I afferents; and last, afferent fiber type determines if and how efferents innervate, whether axodendritically on the afferent, axosomatically on the hair cell, or not at all.
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Affiliation(s)
- Jemma L Webber
- Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - John C Clancy
- Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Yingjie Zhou
- Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Natalia Yraola
- Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Kazuaki Homma
- Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and its Disorders, Northwestern University, Chicago, IL 60611, USA
| | - Jaime García-Añoveros
- Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and its Disorders, Northwestern University, Chicago, IL 60611, USA
- Departments of Neurology and Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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47
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Gene therapy development in hearing research in China. Gene Ther 2020; 27:349-359. [PMID: 32681137 DOI: 10.1038/s41434-020-0177-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 06/13/2020] [Accepted: 07/08/2020] [Indexed: 12/15/2022]
Abstract
Sensorineural hearing loss, the most common form of hearing impairment, is mainly attributable to genetic mutations or acquired factors, such as aging, noise exposure, and ototoxic drugs. In the field of gene therapy, advances in genetic and physiological studies and profound increases in knowledge regarding the underlying mechanisms have yielded great progress in terms of restoring the auditory function in animal models of deafness. Nonetheless, many challenges associated with the translation from basic research to clinical therapies remain to be overcome before a total restoration of auditory function can be expected. In recent years, Chinese research teams have promoted various developmental efforts in this field, including gene sequencing to identify additional potential loci that cause deafness, studies to elucidate the underlying molecular mechanisms, and research to optimize vectors and delivery routes. In this review, we summarize the state of the field and focus mainly on the progress of gene therapy in animal model studies and the optimization of therapeutic strategies in China.
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48
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Sakamoto S, Tateya T, Omori K, Kageyama R. Idgenes are required for morphogenesis and cellular patterning in the developing mammalian cochlea. Dev Biol 2020; 460:164-175. [PMID: 31843520 DOI: 10.1016/j.ydbio.2019.12.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Revised: 12/10/2019] [Accepted: 12/10/2019] [Indexed: 10/25/2022]
Abstract
Inhibitor of differentiation and DNA-binding (Id) proteins, Id1 to Id4, function in the regulation of cellular proliferation and differentiation. Id proteins have been shown to interact with bHLH proteins and other proteins involved in regulating cellular proliferation and differentiation, suggesting a widespread regulatory function. Id1-3 are known to be expressed in the prosensory domain of developing cochlea. However, the roles of Id genes in cochlear development are not fully elucidated. The deficiency of any of the Id1-3 genes individually has little effect on the cochlear development, and therefore the functional redundancy among these genes have been presumed to explain the absence of phenotype. Here, we show that conditional knockout of Id1/2/3 genes (Id TKO) causes major defects in morphogenesis and cellular patterning in the development of mammalian cochlea. Id TKO cochlea was 82% shorter than control, and both decreased proliferation and increased cell death caused the hypomorph. Sox2-positive prosensory domain was formed in Id TKO cochlea, but the formation of the medial-lateral (central-peripheral) axis was disturbed; the boundary between the medial and lateral compartments in the prosensory domain was partially doubled; the number of inner hair cells per unit length increased, and the number of outer hair cells decreased. Furthermore, the lateral non-sensory compartment expressing Bmp4 and Lmo3 was missing. Thus, the patterning of the lateral epithelium was more affected than the medial epithelium. These results suggested that Id genes are crucial for morphogenesis of the cochlea duct and patterning of the lateral epithelium in the developing cochlea. Further analyses by quantitative RT-PCR and immunostaining using cochlear explants with a Bmp pathway inhibitor revealed that the Bmp-Id pathway originates from the lateral non-sensory compartment and promotes outer hair cell differentiation.
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Affiliation(s)
- Susumu Sakamoto
- Department of Otolaryngology, Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan; Kyoto University of Advanced Science, Kyoto, 615-8577, Japan
| | - Tomoko Tateya
- Department of Otolaryngology, Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan; Kyoto University of Advanced Science, Kyoto, 615-8577, Japan; Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan.
| | - Koichi Omori
- Department of Otolaryngology, Head and Neck Surgery, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan
| | - Ryoichiro Kageyama
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, 606-8507, Japan; Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan; Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501, Japan; Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Kyoto, 606-8501, Japan.
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49
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Leyva-Díaz E, Masoudi N, Serrano-Saiz E, Glenwinkel L, Hobert O. Brn3/POU-IV-type POU homeobox genes-Paradigmatic regulators of neuronal identity across phylogeny. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2020; 9:e374. [PMID: 32012462 DOI: 10.1002/wdev.374] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 12/18/2019] [Accepted: 01/07/2020] [Indexed: 02/06/2023]
Abstract
One approach to understand the construction of complex systems is to investigate whether there are simple design principles that are commonly used in building such a system. In the context of nervous system development, one may ask whether the generation of its highly diverse sets of constituents, that is, distinct neuronal cell types, relies on genetic mechanisms that share specific common features. Specifically, are there common patterns in the function of regulatory genes across different neuron types and are those regulatory mechanisms not only used in different parts of one nervous system, but are they conserved across animal phylogeny? We address these questions here by focusing on one specific, highly conserved and well-studied regulatory factor, the POU homeodomain transcription factor UNC-86. Work over the last 30 years has revealed a common and paradigmatic theme of unc-86 function throughout most of the neuron types in which Caenorhabditis elegans unc-86 is expressed. Apart from its role in preventing lineage reiterations during development, UNC-86 operates in combination with distinct partner proteins to initiate and maintain terminal differentiation programs, by coregulating a vast array of functionally distinct identity determinants of specific neuron types. Mouse orthologs of unc-86, the Brn3 genes, have been shown to fulfill a similar function in initiating and maintaining neuronal identity in specific parts of the mouse brain and similar functions appear to be carried out by the sole Drosophila ortholog, Acj6. The terminal selector function of UNC-86 in many different neuron types provides a paradigm for neuronal identity regulation across phylogeny. This article is categorized under: Gene Expression and Transcriptional Hierarchies > Regulatory Mechanisms Invertebrate Organogenesis > Worms Nervous System Development > Vertebrates: Regional Development.
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Affiliation(s)
- Eduardo Leyva-Díaz
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York
| | - Neda Masoudi
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York
| | | | - Lori Glenwinkel
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York
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50
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Zheng Y, Luo W, Ma R, Cong N, Ren D, Chi F, Yang J. The Atoh1 expression levels are correlated with the arrangement, ciliary morphology, and electrophysiological characteristics of ectopic hair cell-like cells. Neurosci Lett 2020; 720:134758. [PMID: 31945449 DOI: 10.1016/j.neulet.2020.134758] [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: 09/16/2019] [Revised: 12/15/2019] [Accepted: 01/13/2020] [Indexed: 10/25/2022]
Abstract
Previous reports have suggested that the level and duration of Atoh1 expression are correlated with the survival, arrangement and stereociliary bundle-related morphology of hair cells during development, but whether Atoh1 expression levels are correlated with the arrangement, bundle formation and electrophysiological characteristics of newly formed hair cells is unknown. To address this question, cultured cochlear explants obtained from neonatal rats were treated with different titers of a human adenovirus serotype 5 (Ad5) vector encoding Atoh1 and/or EGFP (EGFP-Atoh1+/-). The results showed that higher EGFP-Atoh1 concentrations led to higher initial Atoh1 mRNA expression levels and induced greater numbers of ectopic hair cell-like cells (EHCLCs) in the lesser epithelial ridge (LER). Furthermore, gradual increases in the number of EHCLCs were associated with the progressive conversion of the LER region similarly to that of hair cells during development. Some of the cilia on EHCLCs with higher Atoh1 expression were regularly arranged in a manner similar to that of normal hair bundles. As demonstrated through patch clamp recordings, high Atoh1 expression was associated with significantly decreased proportions of cells with Ih currents, significantly reduced proportions of transient potassium channel currents, and potassium channel currents with a greatly increased mean amplitude, which indicated that EHCLCs with high Atoh1 expression were more mature than those with low Atoh1 expression. Overall, the evidence suggests that the Atoh1 expression levels affect not only the arrangement and ciliary morphology of hair cells but also the electrophysiological characteristics of Atoh1-induced EHCLCs, and these findings provide important guidance for future therapies aimed at treating deafness.
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Affiliation(s)
- Yu Zheng
- Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai 200031, China; Shanghai Clinical Medical Center of Hearing Medicine, Shanghai 200031, China; Key Laboratory of Hearing Medicine of National Health Commission of the People's Republic of China, Shanghai 20031, China; Research Institute of Otolaryngology, Fudan University, Shanghai 200031, China
| | - Wenwei Luo
- Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai 200031, China; Shanghai Clinical Medical Center of Hearing Medicine, Shanghai 200031, China; Key Laboratory of Hearing Medicine of National Health Commission of the People's Republic of China, Shanghai 20031, China; Research Institute of Otolaryngology, Fudan University, Shanghai 200031, China
| | - Rui Ma
- Key Laboratory of Hearing Medicine of National Health Commission of the People's Republic of China, Shanghai 20031, China; Research Institute of Otolaryngology, Fudan University, Shanghai 200031, China
| | - Ning Cong
- Key Laboratory of Hearing Medicine of National Health Commission of the People's Republic of China, Shanghai 20031, China; Research Institute of Otolaryngology, Fudan University, Shanghai 200031, China
| | - Dongdong Ren
- Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai 200031, China; Shanghai Clinical Medical Center of Hearing Medicine, Shanghai 200031, China; Key Laboratory of Hearing Medicine of National Health Commission of the People's Republic of China, Shanghai 20031, China; Research Institute of Otolaryngology, Fudan University, Shanghai 200031, China.
| | - Fanglu Chi
- Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai 200031, China; Shanghai Clinical Medical Center of Hearing Medicine, Shanghai 200031, China; Key Laboratory of Hearing Medicine of National Health Commission of the People's Republic of China, Shanghai 20031, China; Research Institute of Otolaryngology, Fudan University, Shanghai 200031, China.
| | - Juanmei Yang
- Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai 200031, China; Shanghai Clinical Medical Center of Hearing Medicine, Shanghai 200031, China; Key Laboratory of Hearing Medicine of National Health Commission of the People's Republic of China, Shanghai 20031, China; Research Institute of Otolaryngology, Fudan University, Shanghai 200031, China.
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