1
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Pavlinkova G, Smolik O. NEUROD1: transcriptional and epigenetic regulator of human and mouse neuronal and endocrine cell lineage programs. Front Cell Dev Biol 2024; 12:1435546. [PMID: 39105169 PMCID: PMC11298428 DOI: 10.3389/fcell.2024.1435546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2024] [Accepted: 07/02/2024] [Indexed: 08/07/2024] Open
Abstract
Transcription factors belonging to the basic helix-loop-helix (bHLH) family are key regulators of cell fate specification and differentiation during development. Their dysregulation is implicated not only in developmental abnormalities but also in various adult diseases and cancers. Recently, the abilities of bHLH factors have been exploited in reprogramming strategies for cell replacement therapy. One such factor is NEUROD1, which has been associated with the reprogramming of the epigenetic landscape and potentially possessing pioneer factor abilities, initiating neuronal developmental programs, and enforcing pancreatic endocrine differentiation. The review aims to consolidate current knowledge on NEUROD1's multifaceted roles and mechanistic pathways in human and mouse cell differentiation and reprogramming, exploring NEUROD1 roles in guiding the development and reprogramming of neuroendocrine cell lineages. The review focuses on NEUROD1's molecular mechanisms, its interactions with other transcription factors, its role as a pioneer factor in chromatin remodeling, and its potential in cell reprogramming. We also show a differential potential of NEUROD1 in differentiation of neurons and pancreatic endocrine cells, highlighting its therapeutic potential and the necessity for further research to fully understand and utilize its capabilities.
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Affiliation(s)
- Gabriela Pavlinkova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, Vestec, Czechia
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2
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Harding AT, Ocwieja K, Jeong M, Zhang Y, Leger V, Jhala N, Stankovic KM, Gehrke L. Human otic progenitor cell models of congenital hearing loss reveal potential pathophysiologic mechanisms of Zika virus and cytomegalovirus infections. mBio 2024; 15:e0019924. [PMID: 38440980 PMCID: PMC11005345 DOI: 10.1128/mbio.00199-24] [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: 01/31/2024] [Accepted: 02/09/2024] [Indexed: 03/06/2024] Open
Abstract
Congenital hearing loss is a common chronic condition affecting children in both developed and developing nations. Viruses correlated with congenital hearing loss include human cytomegalovirus (HCMV) and Zika virus (ZIKV), which causes congenital Zika syndrome. The mechanisms by which HCMV and ZIKV infections cause hearing loss are poorly understood. It is challenging to study human inner ear cells because they are encased in bone and also scarce as autopsy samples. Recent advances in culturing human stem cell-derived otic progenitor cells (OPCs) have allowed us herein to describe successful in vitro infection of OPCs with HCMV and ZIKV, and also to propose potential mechanisms by which each viral infection could affect hearing. We find that ZIKV infection rapidly and significantly induces the expression of type I interferon and interferon-stimulated genes, while OPC viability declines, at least in part, from apoptosis. In contrast, HCMV infection did not appear to upregulate interferons or cause a reduction in cell viability, and instead disrupted expression of key genes and pathways associated with inner ear development and function, including Cochlin, nerve growth factor receptor, SRY-box transcription factor 11, and transforming growth factor-beta signaling. These findings suggest that ZIKV and HCMV infections cause congenital hearing loss through distinct pathways, that is, by inducing progenitor cell death in the case of ZIKV infection, and by disruption of critical developmental pathways in the case of HCMV infection. IMPORTANCE Congenital virus infections inflict substantial morbidity and devastating disease in neonates worldwide, and hearing loss is a common outcome. It has been difficult to study viral infections of the human hearing apparatus because it is embedded in the temporal bone of the skull. Recent technological advances permit the differentiation of otic progenitor cells (OPCs) from human-induced pluripotent stem cells. This paper is important for demonstrating that inner ear virus infections can be modeled in vitro using OPCs. We infected OPCs with two viruses associated with congenital hearing loss: human cytomegalovirus (HCMV), a DNA virus, or Zika virus (ZIKV), an RNA virus. An important result is that the gene expression and cytokine production profiles of HCMV/ZIKV-infected OPCs are markedly dissimilar, suggesting that mechanisms of hearing loss are also distinct. The specific molecular regulatory pathways identified in this work could suggest important targets for therapeutics.
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Affiliation(s)
- Alfred T. Harding
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Karen Ocwieja
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Boston Childrens’ Hospital, Boston, Massachusetts, USA
| | - Minjin Jeong
- Department of Otolaryngology-Head and Neck Surgery, Massachusetts Eye and Ear and Harvard Medical School, Boston, Massachusetts, USA
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California, USA
| | - Yichen Zhang
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Valerie Leger
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Nairuti Jhala
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Konstantina M. Stankovic
- Department of Otolaryngology-Head and Neck Surgery, Massachusetts Eye and Ear and Harvard Medical School, Boston, Massachusetts, USA
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California, USA
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, California, USA
| | - Lee Gehrke
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
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3
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Zine A, Fritzsch B. Early Steps towards Hearing: Placodes and Sensory Development. Int J Mol Sci 2023; 24:6994. [PMID: 37108158 PMCID: PMC10139157 DOI: 10.3390/ijms24086994] [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: 03/09/2023] [Revised: 04/03/2023] [Accepted: 04/06/2023] [Indexed: 04/29/2023] Open
Abstract
Sensorineural hearing loss is the most prevalent sensory deficit in humans. Most cases of hearing loss are due to the degeneration of key structures of the sensory pathway in the cochlea, such as the sensory hair cells, the primary auditory neurons, and their synaptic connection to the hair cells. Different cell-based strategies to replace damaged inner ear neurosensory tissue aiming at the restoration of regeneration or functional recovery are currently the subject of intensive research. Most of these cell-based treatment approaches require experimental in vitro models that rely on a fine understanding of the earliest morphogenetic steps that underlie the in vivo development of the inner ear since its initial induction from a common otic-epibranchial territory. This knowledge will be applied to various proposed experimental cell replacement strategies to either address the feasibility or identify novel therapeutic options for sensorineural hearing loss. In this review, we describe how ear and epibranchial placode development can be recapitulated by focusing on the cellular transformations that occur as the inner ear is converted from a thickening of the surface ectoderm next to the hindbrain known as the otic placode to an otocyst embedded in the head mesenchyme. Finally, we will highlight otic and epibranchial placode development and morphogenetic events towards progenitors of the inner ear and their neurosensory cell derivatives.
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Affiliation(s)
- Azel Zine
- LBN, Laboratory of Bioengineering and Nanoscience, University of Montpellier, 34193 Montpellier, France
| | - Bernd Fritzsch
- Department of Biology, CLAS, University of Iowa, Iowa City, IA 52242, USA
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4
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Fritzsch B, Elliott KL, Yamoah EN. Neurosensory development of the four brainstem-projecting sensory systems and their integration in the telencephalon. Front Neural Circuits 2022; 16:913480. [PMID: 36213204 PMCID: PMC9539932 DOI: 10.3389/fncir.2022.913480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 08/23/2022] [Indexed: 11/18/2022] Open
Abstract
Somatosensory, taste, vestibular, and auditory information is first processed in the brainstem. From the brainstem, the respective information is relayed to specific regions within the cortex, where these inputs are further processed and integrated with other sensory systems to provide a comprehensive sensory experience. We provide the organization, genetics, and various neuronal connections of four sensory systems: trigeminal, taste, vestibular, and auditory systems. The development of trigeminal fibers is comparable to many sensory systems, for they project mostly contralaterally from the brainstem or spinal cord to the telencephalon. Taste bud information is primarily projected ipsilaterally through the thalamus to reach the insula. The vestibular fibers develop bilateral connections that eventually reach multiple areas of the cortex to provide a complex map. The auditory fibers project in a tonotopic contour to the auditory cortex. The spatial and tonotopic organization of trigeminal and auditory neuron projections are distinct from the taste and vestibular systems. The individual sensory projections within the cortex provide multi-sensory integration in the telencephalon that depends on context-dependent tertiary connections to integrate other cortical sensory systems across the four modalities.
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Affiliation(s)
- Bernd Fritzsch
- Department of Biology, The University of Iowa, Iowa City, IA, United States
- Department of Otolaryngology, The University of Iowa, Iowa City, IA, United States
- *Correspondence: Bernd Fritzsch,
| | - Karen L. Elliott
- Department of Biology, The University of Iowa, Iowa City, IA, United States
| | - Ebenezer N. Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno, NV, United States
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5
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Filova I, Pysanenko K, Tavakoli M, Vochyanova S, Dvorakova M, Bohuslavova R, Smolik O, Fabriciova V, Hrabalova P, Benesova S, Valihrach L, Cerny J, Yamoah EN, Syka J, Fritzsch B, Pavlinkova G. ISL1 is necessary for auditory neuron development and contributes toward tonotopic organization. Proc Natl Acad Sci U S A 2022; 119:e2207433119. [PMID: 36074819 PMCID: PMC9478650 DOI: 10.1073/pnas.2207433119] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 08/04/2022] [Indexed: 11/18/2022] Open
Abstract
A cardinal feature of the auditory pathway is frequency selectivity, represented in a tonotopic map from the cochlea to the cortex. The molecular determinants of the auditory frequency map are unknown. Here, we discovered that the transcription factor ISL1 regulates the molecular and cellular features of auditory neurons, including the formation of the spiral ganglion and peripheral and central processes that shape the tonotopic representation of the auditory map. We selectively knocked out Isl1 in auditory neurons using Neurod1Cre strategies. In the absence of Isl1, spiral ganglion neurons migrate into the central cochlea and beyond, and the cochlear wiring is profoundly reduced and disrupted. The central axons of Isl1 mutants lose their topographic projections and segregation at the cochlear nucleus. Transcriptome analysis of spiral ganglion neurons shows that Isl1 regulates neurogenesis, axonogenesis, migration, neurotransmission-related machinery, and synaptic communication patterns. We show that peripheral disorganization in the cochlea affects the physiological properties of hearing in the midbrain and auditory behavior. Surprisingly, auditory processing features are preserved despite the significant hearing impairment, revealing central auditory pathway resilience and plasticity in Isl1 mutant mice. Mutant mice have a reduced acoustic startle reflex, altered prepulse inhibition, and characteristics of compensatory neural hyperactivity centrally. Our findings show that ISL1 is one of the obligatory factors required to sculpt auditory structural and functional tonotopic maps. Still, upon Isl1 deletion, the ensuing central plasticity of the auditory pathway does not suffice to overcome developmentally induced peripheral dysfunction of the cochlea.
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Affiliation(s)
- Iva Filova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Kateryna Pysanenko
- Department of Auditory Neuroscience, Institute of Experimental Medicine Czech Academy of Sciences, 14220 Prague, Czechia
| | - Mitra Tavakoli
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Simona Vochyanova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Martina Dvorakova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Romana Bohuslavova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Ondrej Smolik
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Valeria Fabriciova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Petra Hrabalova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Sarka Benesova
- Laboratory of Gene Expression, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Lukas Valihrach
- Laboratory of Gene Expression, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
| | - Jiri Cerny
- Laboratory of Light Microscopy, Institute of Molecular Genetics Czech Academy of Sciences, 14220 Prague, Czechia
| | - Ebenezer N. Yamoah
- Department of Physiology, School of Medicine, University of Nevada, Reno, NV 89557
| | - Josef Syka
- Department of Auditory Neuroscience, Institute of Experimental Medicine Czech Academy of Sciences, 14220 Prague, Czechia
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA 52242-1324
- Department of Otolaryngology, University of Iowa, Iowa City, IA 52242-1324
| | - Gabriela Pavlinkova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology Czech Academy of Sciences, 25250 Vestec, Czechia
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6
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Elliott KL, Fritzsch B, Yamoah EN, Zine A. Age-Related Hearing Loss: Sensory and Neural Etiology and Their Interdependence. Front Aging Neurosci 2022; 14:814528. [PMID: 35250542 PMCID: PMC8891613 DOI: 10.3389/fnagi.2022.814528] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 01/03/2022] [Indexed: 12/19/2022] Open
Abstract
Age-related hearing loss (ARHL) is a common, increasing problem for older adults, affecting about 1 billion people by 2050. We aim to correlate the different reductions of hearing from cochlear hair cells (HCs), spiral ganglion neurons (SGNs), cochlear nuclei (CN), and superior olivary complex (SOC) with the analysis of various reasons for each one on the sensory deficit profiles. Outer HCs show a progressive loss in a basal-to-apical gradient, and inner HCs show a loss in a apex-to-base progression that results in ARHL at high frequencies after 70 years of age. In early neonates, SGNs innervation of cochlear HCs is maintained. Loss of SGNs results in a considerable decrease (~50% or more) of cochlear nuclei in neonates, though the loss is milder in older mice and humans. The dorsal cochlear nuclei (fusiform neurons) project directly to the inferior colliculi while most anterior cochlear nuclei reach the SOC. Reducing the number of neurons in the medial nucleus of the trapezoid body (MNTB) affects the interactions with the lateral superior olive to fine-tune ipsi- and contralateral projections that may remain normal in mice, possibly humans. The inferior colliculi receive direct cochlear fibers and second-order fibers from the superior olivary complex. Loss of the second-order fibers leads to hearing loss in mice and humans. Although ARHL may arise from many complex causes, HC degeneration remains the more significant problem of hearing restoration that would replace the cochlear implant. The review presents recent findings of older humans and mice with hearing loss.
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Affiliation(s)
- Karen L. Elliott
- Department of Biology, University of Iowa, Iowa City, IA, United States
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, United States
- *Correspondence: Bernd Fritzsch
| | - Ebenezer N. Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, United States
| | - Azel Zine
- LBN, Laboratory of Bioengineering and Nanoscience, University of Montpellier, Montpellier, France
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7
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Filova I, Bohuslavova R, Tavakoli M, Yamoah EN, Fritzsch B, Pavlinkova G. Early Deletion of Neurod1 Alters Neuronal Lineage Potential and Diminishes Neurogenesis in the Inner Ear. Front Cell Dev Biol 2022; 10:845461. [PMID: 35252209 PMCID: PMC8894106 DOI: 10.3389/fcell.2022.845461] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 01/25/2022] [Indexed: 11/13/2022] Open
Abstract
Neuronal development in the inner ear is initiated by expression of the proneural basic Helix-Loop-Helix (bHLH) transcription factor Neurogenin1 that specifies neuronal precursors in the otocyst. The initial specification of the neuroblasts within the otic epithelium is followed by the expression of an additional bHLH factor, Neurod1. Although NEUROD1 is essential for inner ear neuronal development, the different aspects of the temporal and spatial requirements of NEUROD1 for the inner ear and, mainly, for auditory neuron development are not fully understood. In this study, using Foxg1Cre for the early elimination of Neurod1 in the mouse otocyst, we showed that Neurod1 deletion results in a massive reduction of differentiating neurons in the otic ganglion at E10.5, and in the diminished vestibular and rudimental spiral ganglia at E13.5. Attenuated neuronal development was associated with reduced and disorganized sensory epithelia, formation of ectopic hair cells, and the shortened cochlea in the inner ear. Central projections of inner ear neurons with conditional Neurod1 deletion are reduced, unsegregated, disorganized, and interconnecting the vestibular and auditory systems. In line with decreased afferent input from auditory neurons, the volume of cochlear nuclei was reduced by 60% in Neurod1 mutant mice. Finally, our data demonstrate that early elimination of Neurod1 affects the neuronal lineage potential and alters the generation of inner ear neurons and cochlear afferents with a profound effect on the first auditory nuclei, the cochlear nuclei.
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Affiliation(s)
- Iva Filova
- Laboratory of Molecular Pathogenesis, Institute of Biotechnology CAS, Vestec, Czechia
| | - Romana Bohuslavova
- Laboratory of Molecular Pathogenesis, Institute of Biotechnology CAS, Vestec, Czechia
| | - Mitra Tavakoli
- Laboratory of Molecular Pathogenesis, Institute of Biotechnology CAS, Vestec, Czechia
| | - Ebenezer N. Yamoah
- Department of Physiology and Cell Biology, Institute for Neuroscience, University of Nevada, Reno, NV, United States
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, United States
| | - Gabriela Pavlinkova
- Laboratory of Molecular Pathogenesis, Institute of Biotechnology CAS, Vestec, Czechia
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8
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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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9
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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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10
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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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11
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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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12
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Elliott KL, Pavlinkova G, Chizhikov VV, Yamoah EN, Fritzsch B. Neurog1, Neurod1, and Atoh1 are essential for spiral ganglia, cochlear nuclei, and cochlear hair cell development. Fac Rev 2021; 10:47. [PMID: 34131657 PMCID: PMC8170689 DOI: 10.12703/r/10-47] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
We review the molecular basis of three related basic helix–loop–helix (bHLH) genes (Neurog1, Neurod1, and Atoh1) and upstream regulators Eya1/Six1, Sox2, Pax2, Gata3, Fgfr2b, Foxg1, and Lmx1a/b during the development of spiral ganglia, cochlear nuclei, and cochlear hair cells. Neuronal development requires early expression of Neurog1, followed by its downstream target Neurod1, which downregulates Atoh1 expression. In contrast, hair cells and cochlear nuclei critically depend on Atoh1 and require Neurod1 and Neurog1 expression for various aspects of development. Several experiments show a partial uncoupling of Atoh1/Neurod1 (spiral ganglia and cochlea) and Atoh1/Neurog1/Neurod1 (cochlear nuclei). In this review, we integrate the cellular and molecular mechanisms that regulate the development of auditory system and provide novel insights into the restoration of hearing loss, beyond the limited generation of lost sensory neurons and hair cells.
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Affiliation(s)
- Karen L Elliott
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - Gabriela Pavlinkova
- Institute of Biotechnology of the Czech Academy of Sciences, 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, University of Nevada, Reno, NV, USA
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, USA
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13
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Warnecke A, Giesemann A. Embryology, Malformations, and Rare Diseases of the Cochlea. Laryngorhinootologie 2021; 100:S1-S43. [PMID: 34352899 PMCID: PMC8354575 DOI: 10.1055/a-1349-3824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Despite the low overall prevalence of individual rare diseases, cochlear
dysfunction leading to hearing loss represents a symptom in a large
proportion. The aim of this work was to provide a clear overview of rare
cochlear diseases, taking into account the embryonic development of the
cochlea and the systematic presentation of the different disorders. Although
rapid biotechnological and bioinformatic advances may facilitate the
diagnosis of a rare disease, an interdisciplinary exchange is often required
to raise the suspicion of a rare disease. It is important to recognize that
the phenotype of rare inner ear diseases can vary greatly not only in
non-syndromic but also in syndromic hearing disorders. Finally, it becomes
clear that the phenotype of the individual rare diseases cannot be
determined exclusively by classical genetics even in monogenetic
disorders.
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Affiliation(s)
- Athanasia Warnecke
- Klinik für Hals-, Nasen- und Ohrenheilkunde, Medizinische Hochschule Hannover, Carl-Neuberg-Straße 1, 30625 Hannover.,Deutsche Forschungsgemeinschaft Exzellenzcluster"Hearing4all" - EXC 2177/1 - Project ID 390895286
| | - Anja Giesemann
- Institut für Neuroradiologie, Medizinische Hochschule Hannover, Carl-Neuberg-Straße 1, 30625 Hannover
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14
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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: 37] [Impact Index Per Article: 12.3] [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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15
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Jahan I, Kersigo J, Elliott KL, Fritzsch B. Smoothened overexpression causes trochlear motoneurons to reroute and innervate ipsilateral eyes. Cell Tissue Res 2021; 384:59-72. [PMID: 33409653 DOI: 10.1007/s00441-020-03352-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 11/16/2020] [Indexed: 12/22/2022]
Abstract
The trochlear projection is unique among the cranial nerves in that it exits the midbrain dorsally to innervate the contralateral superior oblique muscle in all vertebrates. Trochlear as well as oculomotor motoneurons uniquely depend upon Phox2a and Wnt1, both of which are downstream of Lmx1b, though why trochlear motoneurons display such unusual projections is not fully known. We used Pax2-cre to drive expression of ectopically activated Smoothened (SmoM2) dorsally in the midbrain and anterior hindbrain. We documented the expansion of oculomotor and trochlear motoneurons using Phox2a as a specific marker at E9.5. We show that the initial expansion follows a demise of these neurons by E14.5. Furthermore, SmoM2 expression leads to a ventral exit and ipsilateral projection of trochlear motoneurons. We compare that data with Unc5c mutants that shows a variable ipsilateral number of trochlear fibers that exit dorsal. Our data suggest that Shh signaling is involved in trochlear motoneuron projections and that the deflected trochlear projections after SmoM2 expression is likely due to the dorsal expression of Gli1, which impedes the normal dorsal trajectory of these neurons.
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Affiliation(s)
- Israt Jahan
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA
| | - Jennifer Kersigo
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA
| | - Karen L Elliott
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA. .,Department of Otolaryngology, University of Iowa, Iowa City, IA, 52242, USA.
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16
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Kersigo J, Gu L, Xu L, Pan N, Vijayakuma S, Jones T, Shibata SB, Fritzsch B, Hansen MR. Effects of Neurod1 Expression on Mouse and Human Schwannoma Cells. Laryngoscope 2021; 131:E259-E270. [PMID: 32438526 PMCID: PMC7772964 DOI: 10.1002/lary.28671] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 03/11/2020] [Accepted: 03/18/2020] [Indexed: 12/22/2022]
Abstract
OBJECTIVES The objective was to explore the effect of the proneuronal transcription factor neurogenic differentiation 1 (Neurod1, ND1) on Schwann cells (SC) and schwannoma cell proliferation. METHODS Using a variety of transgenic mouse lines, we investigated how expression of Neurod1 effects medulloblastoma (MB) growth, schwannoma tumor progression, vestibular function, and SC cell proliferation. Primary human vestibular schwannoma (VS) cell cultures were transduced with adenoviral vectors expressing Neurod1. Cell proliferation was assessed by 5-ethynyl-2'-deoxyuridine (EdU) uptake. STUDY DESIGN Basic science investigation. RESULTS Expression of Neurod1 reduced the growth of slow-growing but not fast-growing MB models. Gene transfer of Neurod1 in human schwannoma cultures significantly reduced cell proliferation in dose-dependent way. Deletion of the neurofibromatosis type 2 (Nf2) tumor-suppressor gene via Cre expression in SCs led to increased intraganglionic SC proliferation and mildly reduced vestibular sensory-evoked potentials (VsEP) responses compared to age-matched wild-type littermates. The effect of Neurod1-induced expression on intraganglionic SC proliferation in animals lacking Nf2 was mild and highly variable. Sciatic nerve axotomy significantly increased SC proliferation in wild-type and Nf2-null animals, and expression of Neurod1 reduced the proliferative capacity of both wild-type and Nf2-null SCs following nerve injury. CONCLUSION Expression of Neurod1 reduces slow-growing MB progression and reduces human SC proliferation in primary VS cultures. In a genetic mouse model of schwannomas, we find some effects of Neurod1 expression; however, the high variability indicates that more tightly regulated Neurod1 expression levels that mimic our in vitro data are needed to fully validate Neurod1 effects on schwannoma progression. LEVEL OF EVIDENCE NA Laryngoscope, 131:E259-E270, 2021.
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Affiliation(s)
- Jennifer Kersigo
- Department of Biology, University of Lowa, Lowa City, Lowa, U.S.A
| | - Lintao Gu
- Department of Otolaryngology, University of Lowa, Lowa City, Lowa, U.S.A
- Decibel Pharmaceutical, Boston, Massachusetts, U.S.A
| | - Linjing Xu
- Department of Otolaryngology, University of Lowa, Lowa City, Lowa, U.S.A
| | - Ning Pan
- Department of Biology, University of Lowa, Lowa City, Lowa, U.S.A
- Department of Special Education & Communication Disorders, University of Nebraska, Lincoln, Nebraska, U.S.A
| | - Sarath Vijayakuma
- Department of Otolaryngology, The First Affiliated Hospital of Shandong First Medical University, Jinan, Shandong, China
| | - Timothy Jones
- Department of Otolaryngology, The First Affiliated Hospital of Shandong First Medical University, Jinan, Shandong, China
| | - Seiji B Shibata
- Department of Otolaryngology, University of Lowa, Lowa City, Lowa, U.S.A
| | - Bernd Fritzsch
- Department of Biology, University of Lowa, Lowa City, Lowa, U.S.A
- Department of Otolaryngology, University of Lowa, Lowa City, Lowa, U.S.A
| | - Marlan R Hansen
- Department of Otolaryngology, University of Lowa, Lowa City, Lowa, U.S.A
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17
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Pavlinkova G. Molecular Aspects of the Development and Function of Auditory Neurons. Int J Mol Sci 2020; 22:ijms22010131. [PMID: 33374462 PMCID: PMC7796308 DOI: 10.3390/ijms22010131] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/21/2020] [Accepted: 12/22/2020] [Indexed: 01/08/2023] Open
Abstract
This review provides an up-to-date source of information on the primary auditory neurons or spiral ganglion neurons in the cochlea. These neurons transmit auditory information in the form of electric signals from sensory hair cells to the first auditory nuclei of the brain stem, the cochlear nuclei. Congenital and acquired neurosensory hearing loss affects millions of people worldwide. An increasing body of evidence suggest that the primary auditory neurons degenerate due to noise exposure and aging more readily than sensory cells, and thus, auditory neurons are a primary target for regenerative therapy. A better understanding of the development and function of these neurons is the ultimate goal for long-term maintenance, regeneration, and stem cell replacement therapy. In this review, we provide an overview of the key molecular factors responsible for the function and neurogenesis of the primary auditory neurons, as well as a brief introduction to stem cell research focused on the replacement and generation of auditory neurons.
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Affiliation(s)
- Gabriela Pavlinkova
- BIOCEV, Institute of Biotechnology of the Czech Academy of Sciences, 25250 Vestec, Czech Republic
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18
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Filova I, Dvorakova M, Bohuslavova R, Pavlinek A, Elliott KL, Vochyanova S, Fritzsch B, Pavlinkova G. Combined Atoh1 and Neurod1 Deletion Reveals Autonomous Growth of Auditory Nerve Fibers. Mol Neurobiol 2020; 57:5307-5323. [PMID: 32880858 PMCID: PMC7547283 DOI: 10.1007/s12035-020-02092-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Accepted: 08/24/2020] [Indexed: 12/24/2022]
Abstract
Ear development requires the transcription factors ATOH1 for hair cell differentiation and NEUROD1 for sensory neuron development. In addition, NEUROD1 negatively regulates Atoh1 gene expression. As we previously showed that deletion of the Neurod1 gene in the cochlea results in axon guidance defects and excessive peripheral innervation of the sensory epithelium, we hypothesized that some of the innervation defects may be a result of abnormalities in NEUROD1 and ATOH1 interactions. To characterize the interdependency of ATOH1 and NEUROD1 in inner ear development, we generated a new Atoh1/Neurod1 double null conditional deletion mutant. Through careful comparison of the effects of single Atoh1 or Neurod1 gene deletion with combined double Atoh1 and Neurod1 deletion, we demonstrate that NEUROD1-ATOH1 interactions are not important for the Neurod1 null innervation phenotype. We report that neurons lacking Neurod1 can innervate the flat epithelium without any sensory hair cells or supporting cells left after Atoh1 deletion, indicating that neurons with Neurod1 deletion do not require the presence of hair cells for axon growth. Moreover, transcriptome analysis identified genes encoding axon guidance and neurite growth molecules that are dysregulated in the Neurod1 deletion mutant. Taken together, we demonstrate that much of the projections of NEUROD1-deprived inner ear sensory neurons are regulated cell-autonomously.
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Affiliation(s)
- Iva Filova
- Institute of Biotechnology of the Czech Academy of Sciences, 25250, Vestec, Czechia
| | - Martina Dvorakova
- Institute of Biotechnology of the Czech Academy of Sciences, 25250, Vestec, Czechia
| | - Romana Bohuslavova
- Institute of Biotechnology of the Czech Academy of Sciences, 25250, Vestec, Czechia
| | - Adam Pavlinek
- Institute of Biotechnology of the Czech Academy of Sciences, 25250, Vestec, Czechia
| | - Karen L Elliott
- Department of Biology, University of Iowa, Iowa City, IA, 52242-1324, USA
| | - Simona Vochyanova
- Institute of Biotechnology of the Czech Academy of Sciences, 25250, Vestec, Czechia
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, 52242-1324, USA.
| | - Gabriela Pavlinkova
- Institute of Biotechnology of the Czech Academy of Sciences, 25250, Vestec, Czechia.
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19
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Transcription Factors of the bHLH Family Delineate Vertebrate Landmarks in the Nervous System of a Simple Chordate. Genes (Basel) 2020; 11:genes11111262. [PMID: 33114624 PMCID: PMC7693978 DOI: 10.3390/genes11111262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Accepted: 10/12/2020] [Indexed: 02/07/2023] Open
Abstract
Tunicates are marine invertebrates whose tadpole-like larvae feature a highly simplified version of the chordate body plan. Similar to their distant vertebrate relatives, tunicate larvae develop a regionalized central nervous system and form distinct neural structures, which include a rostral sensory vesicle, a motor ganglion, and a caudal nerve cord. The sensory vesicle contains a photoreceptive complex and a statocyst, and based on the comparable expression patterns of evolutionarily conserved marker genes, it is believed to include proto-hypothalamic and proto-retinal territories. The evolutionarily conserved molecular fingerprints of these landmarks of the vertebrate brain consist of genes encoding for different transcription factors, and of the gene batteries that they control, and include several members of the bHLH family. Here we review the complement of bHLH genes present in the streamlined genome of the tunicate Ciona robusta and their current classification, and summarize recent studies on proneural bHLH transcription factors and their expression territories. We discuss the possible roles of bHLH genes in establishing the molecular compartmentalization of the enticing nervous system of this unassuming chordate.
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20
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Matern MS, Milon B, Lipford EL, McMurray M, Ogawa Y, Tkaczuk A, Song Y, Elkon R, Hertzano R. GFI1 functions to repress neuronal gene expression in the developing inner ear hair cells. Development 2020; 147:147/17/dev186015. [PMID: 32917668 PMCID: PMC7502595 DOI: 10.1242/dev.186015] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 07/24/2020] [Indexed: 01/24/2023]
Abstract
Despite the known importance of the transcription factors ATOH1, POU4F3 and GFI1 in hair cell development and regeneration, their downstream transcriptional cascades in the inner ear remain largely unknown. Here, we have used Gfi1cre;RiboTag mice to evaluate changes to the hair cell translatome in the absence of GFI1. We identify a systematic downregulation of hair cell differentiation genes, concomitant with robust upregulation of neuronal genes in the GFI1-deficient hair cells. This includes increased expression of neuronal-associated transcription factors (e.g. Pou4f1) as well as transcription factors that serve dual roles in hair cell and neuronal development (e.g. Neurod1, Atoh1 and Insm1). We further show that the upregulated genes are consistent with the NEUROD1 regulon and are normally expressed in hair cells prior to GFI1 onset. Additionally, minimal overlap of differentially expressed genes in auditory and vestibular hair cells suggests that GFI1 serves different roles in these systems. From these data, we propose a dual mechanism for GFI1 in promoting hair cell development, consisting of repression of neuronal-associated genes as well as activation of hair cell-specific genes required for normal functional maturation.
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Affiliation(s)
- Maggie S. Matern
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Beatrice Milon
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Erika L. Lipford
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Mark McMurray
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Yoko Ogawa
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Andrew Tkaczuk
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Yang Song
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Ran Elkon
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ronna Hertzano
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA .,Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA.,Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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21
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Yamoah EN, Li M, Shah A, Elliott KL, Cheah K, Xu PX, Phillips S, Young SM, Eberl DF, Fritzsch B. Using Sox2 to alleviate the hallmarks of age-related hearing loss. Ageing Res Rev 2020; 59:101042. [PMID: 32173536 PMCID: PMC7261488 DOI: 10.1016/j.arr.2020.101042] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 03/04/2020] [Accepted: 03/05/2020] [Indexed: 02/07/2023]
Abstract
Age-related hearing loss (ARHL) is the most prevalent sensory deficit. ARHL reduces the quality of life of the growing population, setting seniors up for the enhanced mental decline. The size of the needy population, the structural deficit, and a likely research strategy for effective treatment of chronic neurosensory hearing in the elderly are needed. Although there has been profound advancement in auditory regenerative research, there remain multiple challenges to restore hearing loss. Thus, additional investigations are required, using novel tools. We propose how the (1) flat epithelium, remaining after the organ of Corti has deteriorated, can be converted to the repaired-sensory epithelium, using Sox2. This will include (2) developing an artificial gene regulatory network transmitted by (3) large viral vectors to the flat epithelium to stimulate remnants of the organ of Corti to restore hair cells. We hope to unite with our proposal toward the common goal, eventually restoring a functional human hearing organ by transforming the flat epithelial cells left after the organ of Corti loss.
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Affiliation(s)
- Ebenezer N Yamoah
- Department of Physiology and Cell Biology, University of Nevada, Reno, USA
| | - Mark Li
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, USA
| | - Anit Shah
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, USA
| | - Karen L Elliott
- Department of Biology, CLAS, University of Iowa, Iowa City, USA
| | - Kathy Cheah
- Department of Biochemistry, Hong Kong University, Hong Kong, China
| | - Pin-Xian Xu
- Department of Biochemistry, Hong Kong University, Hong Kong, China
| | - Stacia Phillips
- Department of Biochemistry, Hong Kong University, Hong Kong, China
| | - Samuel M Young
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, USA; Department of Otolaryngology, Iowa Neuroscience Institute, University of Iowa, Iowa City, USA
| | - Daniel F Eberl
- Department of Biology, CLAS, University of Iowa, Iowa City, USA
| | - Bernd Fritzsch
- Department of Biology, CLAS, University of Iowa, Iowa City, USA.
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22
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Zhang S, Zhang Y, Dong Y, Guo L, Zhang Z, Shao B, Qi J, Zhou H, Zhu W, Yan X, Hong G, Zhang L, Zhang X, Tang M, Zhao C, Gao X, Chai R. Knockdown of Foxg1 in supporting cells increases the trans-differentiation of supporting cells into hair cells in the neonatal mouse cochlea. Cell Mol Life Sci 2020; 77:1401-1419. [PMID: 31485717 PMCID: PMC7113235 DOI: 10.1007/s00018-019-03291-2] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 08/08/2019] [Accepted: 08/28/2019] [Indexed: 12/17/2022]
Abstract
Foxg1 is one of the forkhead box genes that are involved in morphogenesis, cell fate determination, and proliferation, and Foxg1 was previously reported to be required for morphogenesis of the mammalian inner ear. However, Foxg1 knock-out mice die at birth, and thus the role of Foxg1 in regulating hair cell (HC) regeneration after birth remains unclear. Here we used Sox2CreER/+ Foxg1loxp/loxp mice and Lgr5-EGFPCreER/+ Foxg1loxp/loxp mice to conditionally knock down Foxg1 specifically in Sox2+ SCs and Lgr5+ progenitors, respectively, in neonatal mice. We found that Foxg1 conditional knockdown (cKD) in Sox2+ SCs and Lgr5+ progenitors at postnatal day (P)1 both led to large numbers of extra HCs, especially extra inner HCs (IHCs) at P7, and these extra IHCs with normal hair bundles and synapses could survive at least to P30. The EdU assay failed to detect any EdU+ SCs, while the SC number was significantly decreased in Foxg1 cKD mice, and lineage tracing data showed that much more tdTomato+ HCs originated from Sox2+ SCs in Foxg1 cKD mice compared to the control mice. Moreover, the sphere-forming assay showed that Foxg1 cKD in Lgr5+ progenitors did not significantly change their sphere-forming ability. All these results suggest that Foxg1 cKD promotes HC regeneration and leads to large numbers of extra HCs probably by inducing direct trans-differentiation of SCs and progenitors to HCs. Real-time qPCR showed that cell cycle and Notch signaling pathways were significantly down-regulated in Foxg1 cKD mice cochlear SCs. Together, this study provides new evidence for the role of Foxg1 in regulating HC regeneration from SCs and progenitors in the neonatal mouse cochlea.
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Affiliation(s)
- Shasha Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Yuan Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Ying Dong
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Lingna Guo
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Zhong Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Buwei Shao
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Jieyu Qi
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Han Zhou
- Jiangsu Provincial Key Medical Discipline (Laboratory), Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - Weijie Zhu
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Xiaoqian Yan
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Guodong Hong
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Liyan Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Xiaoli Zhang
- Jiangsu Provincial Key Medical Discipline (Laboratory), Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - Mingliang Tang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Chunjie Zhao
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China
| | - Xia Gao
- Jiangsu Provincial Key Medical Discipline (Laboratory), Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - Renjie Chai
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, 210096, China.
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China.
- Institute for Stem Cell and Regeneration, Chinese Academy of Science, Beijing, China.
- Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 211189, China.
- Jiangsu Provincial Key Medical Discipline (Laboratory), Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, China.
- Key Laboratory of Hearing Medicine of NHFPC, ENT Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, Shanghai Engineering Research Centre of Cochlear Implant, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, China.
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23
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Li HJ, Ray SK, Pan N, Haigh J, Fritzsch B, Leiter AB. Intestinal Neurod1 expression impairs paneth cell differentiation and promotes enteroendocrine lineage specification. Sci Rep 2019; 9:19489. [PMID: 31862906 PMCID: PMC6925293 DOI: 10.1038/s41598-019-55292-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 11/25/2019] [Indexed: 12/12/2022] Open
Abstract
Transcription factor Neurod1 is required for enteroendocrine progenitor differentiation and maturation. Several earlier studies indicated that ectopic expression of Neurod1 converted non- neuronal cells into neurons. However, the functional consequence of ectopic Neurod1 expression has not been examined in the GI tract, and it is not known whether Neurod1 can similarly switch cell fates in the intestine. We generated a mouse line that would enable us to conditionally express Neurod1 in intestinal epithelial cells at different stages of differentiation. Forced expression of Neurod1 throughout intestinal epithelium increased the number of EECs as well as the expression of EE specific transcription factors and hormones. Furthermore, we observed a substantial reduction of Paneth cell marker expression, although the expressions of enterocyte-, tuft- and goblet-cell specific markers are largely not affected. Our earlier study indicated that Neurog3+ progenitor cells give rise to not only EECs but also Goblet and Paneth cells. Here we show that the conditional expression of Neurod1 restricts Neurog3+ progenitors to adopt Paneth cell fate, and promotes more pronounced EE cell differentiation, while such effects are not seen in more differentiated Neurod1+ cells. Together, our data suggest that forced expression of Neurod1 programs intestinal epithelial cells more towards an EE cell fate at the expense of the Paneth cell lineage and the effect ceases as cells mature to EE cells.
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Affiliation(s)
- Hui Joyce Li
- Division of Gastroenterology, Department of Medicine, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, 01605, USA
| | - Subir K Ray
- Division of Gastroenterology, Department of Medicine, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, 01605, USA
| | - Ning Pan
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA
- Decibel Pharmaceutical, Boston, MA, USA
| | - Jody Haigh
- Department of Biomedical, Molecular Biology, Ghent University, Ghent, Belgium
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA
| | - Andrew B Leiter
- Division of Gastroenterology, Department of Medicine, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, 01605, USA.
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24
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Giffen KP, Liu H, Kramer KL, He DZ. Expression of Protein-Coding Gene Orthologs in Zebrafish and Mouse Inner Ear Non-sensory Supporting Cells. Front Neurosci 2019; 13:1117. [PMID: 31680844 PMCID: PMC6813431 DOI: 10.3389/fnins.2019.01117] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 10/03/2019] [Indexed: 11/13/2022] Open
Abstract
Non-mammalian vertebrates, including zebrafish, retain the ability to regenerate hair cells (HCs) due to unknown molecular mechanisms that regulate proliferation and conversion of non-sensory supporting cells (nsSCs) to HCs. This regenerative capacity is not conserved in mammals. Identification of uniquely expressed orthologous genes in zebrafish nsSCs may reveal gene candidates involved in the proliferation and transdifferentiation of zebrafish nsSCs to HCs in the inner ear. A list of orthologous protein-coding genes was generated based on an Ensembl Biomart comparison of the zebrafish and mouse genomes. Our previously published RNA-seq-based transcriptome datasets of isolated inner ear zebrafish nsSCs and HCs, and mouse non-sensory supporting pillar and Deiters’ cells, and HCs, were merged to analyze gene expression patterns between the two species. Out of 17,498 total orthologs, 11,752 were expressed in zebrafish nsSCs and over 10,000 orthologs were expressed in mouse pillar and Deiters’ cells. Differentially expressed genes common among the zebrafish nsSCs and mouse pillar and Deiters’ cells, compared to species-specific HCs, included 306 downregulated and 314 upregulated genes; however, over 1,500 genes were uniquely upregulated in zebrafish nsSCs. Functional analysis of genes uniquely expressed in nsSCs identified several transcription factors associated with cell fate determination, cell differentiation and nervous system development, indicating inherent molecular properties of nsSCs that promote self-renewal and transdifferentiation into new HCs. Our study provides a means of characterizing these orthologous genes, involved in proliferation and transdifferentiation of nsSCs to HCs in zebrafish, which may lead to identification of potential targets for HC regeneration in mammals.
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Affiliation(s)
- Kimberlee P Giffen
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States
| | - Huizhan Liu
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States
| | - Kenneth L Kramer
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States
| | - David Z He
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States
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25
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Schmidt H, Fritzsch B. Npr2 null mutants show initial overshooting followed by reduction of spiral ganglion axon projections combined with near-normal cochleotopic projection. Cell Tissue Res 2019; 378:15-32. [PMID: 31201541 PMCID: PMC7243364 DOI: 10.1007/s00441-019-03050-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 05/20/2019] [Indexed: 12/19/2022]
Abstract
Npr2 (natriuretic peptide receptor 2) affects bifurcation of neural crest or placode-derived afferents upon entering the brain stem/spinal cord, leading to a lack of either rostral or caudal branches. Previous work has shown that early embryonic growth of cochlear and vestibular afferents is equally affected in this mutant but later work on postnatal Npr2 point mutations suggested some additional effects on the topology of afferent projections and mild functional defects. Using multicolor lipophilic dye tracing, we show that absence of Npr2 has little to no effect on the initial patterning of inner ear afferents with respect to their dorsoventral cochleotopic-specific projections. However, in contrast to control animals, we found a variable degree of embryonic extension of auditory afferents beyond the boundaries of the anterior cochlear nucleus into the cerebellum that emanates only from apical spiral ganglion neurons. Such expansion has previously only been reported for Hox gene mutants and implies an unclear interaction of Hox codes with Npr2-mediated afferent projection patterning to define boundaries. Some vestibular ganglion neurons expand their projections to reach the cochlear apex and the cochlear nuclei, comparable to previous findings in Neurod1 mutant mice. Before birth, such expansions are reduced or lost leading to truncated projections to the anteroventral cochlear nucleus and expansion of low-frequency fibers of the apex to the posteroventral cochlear nucleus.
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Affiliation(s)
- Hannes Schmidt
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Bernd Fritzsch
- Department of Biology & Department of Otolaryngology, CLAS, University of Iowa, 128 Jefferson Avenue, Iowa City, IA, 52242, USA.
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26
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β-Catenin is required for radial cell patterning and identity in the developing mouse cochlea. Proc Natl Acad Sci U S A 2019; 116:21054-21060. [PMID: 31570588 DOI: 10.1073/pnas.1910223116] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Development of multicellular organs requires the coordination of cell differentiation and patterning. Critical for sound detection, the mammalian organ of Corti contains functional units arranged tonotopically along the cochlear turns. Each unit consists of sensory hair cells intercalated by nonsensory supporting cells, both specified and radially patterned with exquisite precision during embryonic development. However, how cell identity and radial patterning are jointly controlled is poorly understood. Here we show that β-catenin is required for specification of hair cell and supporting cell subtypes and radial patterning of the cochlea in vivo. In 2 mouse models of conditional β-catenin deletion, early specification of Myosin7-expressing hair cells and Prox1-positive supporting cells was preserved. While β-catenin-deficient cochleae expressed FGF8 and FGFR3, both of which are essential for pillar cell specification, the radial patterning of organ of Corti was disrupted, revealed by aberrant expression of cadherins and the pillar cell markers P75 and Lgr6. Moreover, β-catenin ablation caused duplication of FGF8-positive inner hair cells and reduction of outer hair cells without affecting the overall hair cell density. In contrast, in another transgenic model with suppressed transcriptional activity of β-catenin but preserved cell adhesion function, both specification and radial patterning of the organ of Corti were intact. Our study reveals specific functions of β-catenin in governing cell identity and patterning mediated through cell adhesion in the developing cochlea.
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27
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Michalski N, Petit C. Genes Involved in the Development and Physiology of Both the Peripheral and Central Auditory Systems. Annu Rev Neurosci 2019; 42:67-86. [DOI: 10.1146/annurev-neuro-070918-050428] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The genetic approach, based on the study of inherited forms of deafness, has proven to be particularly effective for deciphering the molecular mechanisms underlying the development of the peripheral auditory system, the cochlea and its afferent auditory neurons, and how this system extracts the physical parameters of sound. Although this genetic dissection has provided little information about the central auditory system, scattered data suggest that some genes may have a critical role in both the peripheral and central auditory systems. Here, we review the genes controlling the development and function of the peripheral and central auditory systems, focusing on those with demonstrated intrinsic roles in both systems and highlighting the current underappreciation of these genes. Their encoded products are diverse, from transcription factors to ion channels, as are their roles in the central auditory system, mostly evaluated in brainstem nuclei. We examine the ontogenetic and evolutionary mechanisms that may underlie their expression at different sites.
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Affiliation(s)
- Nicolas Michalski
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, 75015 Paris, France;,
- Institut National de la Santé et de la Recherche Médicale, UMRS 1120, 75015 Paris, France
- Sorbonne Universités, 75005 Paris, France
| | - Christine Petit
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, 75015 Paris, France;,
- Institut National de la Santé et de la Recherche Médicale, UMRS 1120, 75015 Paris, France
- Sorbonne Universités, 75005 Paris, France
- Syndrome de Usher et Autres Atteintes Rétino-Cochléaires, Institut de la Vision, 75012 Paris, France
- Collège de France, 75005 Paris, France
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28
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Yang LM, Cheah KSE, Huh SH, Ornitz DM. Sox2 and FGF20 interact to regulate organ of Corti hair cell and supporting cell development in a spatially-graded manner. PLoS Genet 2019; 15:e1008254. [PMID: 31276493 PMCID: PMC6636783 DOI: 10.1371/journal.pgen.1008254] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 07/17/2019] [Accepted: 06/18/2019] [Indexed: 01/24/2023] Open
Abstract
The mouse organ of Corti, housed inside the cochlea, contains hair cells and supporting cells that transduce sound into electrical signals. These cells develop in two main steps: progenitor specification followed by differentiation. Fibroblast Growth Factor (FGF) signaling is important in this developmental pathway, as deletion of FGF receptor 1 (Fgfr1) or its ligand, Fgf20, leads to the loss of hair cells and supporting cells from the organ of Corti. However, whether FGF20-FGFR1 signaling is required during specification or differentiation, and how it interacts with the transcription factor Sox2, also important for hair cell and supporting cell development, has been a topic of debate. Here, we show that while FGF20-FGFR1 signaling functions during progenitor differentiation, FGFR1 has an FGF20-independent, Sox2-dependent role in specification. We also show that a combination of reduction in Sox2 expression and Fgf20 deletion recapitulates the Fgfr1-deletion phenotype. Furthermore, we uncovered a strong genetic interaction between Sox2 and Fgf20, especially in regulating the development of hair cells and supporting cells towards the basal end and the outer compartment of the cochlea. To explain this genetic interaction and its effects on the basal end of the cochlea, we provide evidence that decreased Sox2 expression delays specification, which begins at the apex of the cochlea and progresses towards the base, while Fgf20-deletion results in premature onset of differentiation, which begins near the base of the cochlea and progresses towards the apex. Thereby, Sox2 and Fgf20 interact to ensure that specification occurs before differentiation towards the cochlear base. These findings reveal an intricate developmental program regulating organ of Corti development along the basal-apical axis of the cochlea.
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Affiliation(s)
- Lu M. Yang
- Department of Developmental Biology; Washington University School of Medicine; St. Louis, Missouri, United States of America
| | - Kathryn S. E. Cheah
- School of Biomedical Sciences; The University of Hong Kong; Pokfulam, Hong Kong, China
| | - Sung-Ho Huh
- Department of Developmental Biology; Washington University School of Medicine; St. Louis, Missouri, United States of America
- Holland Regenerative Medicine Program, and the Department of Neurological Sciences; University of Nebraska Medical Center; Omaha, Nebraska, United States of America
- * E-mail: (DMO); (SH)
| | - David M. Ornitz
- Department of Developmental Biology; Washington University School of Medicine; St. Louis, Missouri, United States of America
- * E-mail: (DMO); (SH)
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29
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Macova I, Pysanenko K, Chumak T, Dvorakova M, Bohuslavova R, Syka J, Fritzsch B, Pavlinkova G. Neurod1 Is Essential for the Primary Tonotopic Organization and Related Auditory Information Processing in the Midbrain. J Neurosci 2019; 39:984-1004. [PMID: 30541910 PMCID: PMC6363931 DOI: 10.1523/jneurosci.2557-18.2018] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 11/17/2018] [Accepted: 12/05/2018] [Indexed: 02/06/2023] Open
Abstract
Hearing depends on extracting frequency, intensity, and temporal properties from sound to generate an auditory map for acoustical signal processing. How physiology intersects with molecular specification to fine tune the developing properties of the auditory system that enable these aspects remains unclear. We made a novel conditional deletion model that eliminates the transcription factor NEUROD1 exclusively in the ear. These mice (both sexes) develop a truncated frequency range with no neuroanatomically recognizable mapping of spiral ganglion neurons onto distinct locations in the cochlea nor a cochleotopic map presenting topographically discrete projections to the cochlear nuclei. The disorganized primary cochleotopic map alters tuning properties of the inferior colliculus units, which display abnormal frequency, intensity, and temporal sound coding. At the behavioral level, animals show alterations in the acoustic startle response, consistent with altered neuroanatomical and physiological properties. We demonstrate that absence of the primary afferent topology during embryonic development leads to dysfunctional tonotopy of the auditory system. Such effects have never been investigated in other sensory systems because of the lack of comparable single gene mutation models.SIGNIFICANCE STATEMENT All sensory systems form a topographical map of neuronal projections from peripheral sensory organs to the brain. Neuronal projections in the auditory pathway are cochleotopically organized, providing a tonotopic map of sound frequencies. Primary sensory maps typically arise by molecular cues, requiring physiological refinements. Past work has demonstrated physiologic plasticity in many senses without ever molecularly undoing the specific mapping of an entire primary sensory projection. We genetically manipulated primary auditory neurons to generate a scrambled cochleotopic projection. Eliminating tonotopic representation to auditory nuclei demonstrates the inability of physiological processes to restore a tonotopic presentation of sound in the midbrain. Our data provide the first insights into the limits of physiology-mediated brainstem plasticity during the development of the auditory system.
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Affiliation(s)
- Iva Macova
- Institute of Biotechnology CAS, Vestec, Czechia 25250
- Faculty of Science, Charles University, Prague, Czechia 12843
| | | | - Tetyana Chumak
- Institute of Experimental Medicine CAS, Prague, Czechia 14220
| | - Martina Dvorakova
- Institute of Biotechnology CAS, Vestec, Czechia 25250
- Faculty of Science, Charles University, Prague, Czechia 12843
| | | | - Josef Syka
- Institute of Experimental Medicine CAS, Prague, Czechia 14220
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, Iowa 52242, and
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30
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Jahan I, Elliott KL, Fritzsch B. Understanding Molecular Evolution and Development of the Organ of Corti Can Provide Clues for Hearing Restoration. Integr Comp Biol 2018; 58:351-365. [PMID: 29718413 PMCID: PMC6104702 DOI: 10.1093/icb/icy019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The mammalian hearing organ is a stereotyped cellular assembly with orderly innervation: two types of spiral ganglion neurons (SGNs) innervate two types of differentially distributed hair cells (HCs). HCs and SGNs evolved from single neurosensory cells through gene multiplication and diversification. Independent regulation of HCs and neuronal differentiation through expression of basic helix-loop-helix transcription factors (bHLH TFs: Atoh1, Neurog1, Neurod1) led to the evolution of vestibular HC assembly and their unique type of innervation. In ancestral mammals, a vestibular organ was transformed into the organ of Corti (OC) containing a single row of inner HC (IHC), three rows of outer HCs (OHCs), several unique supporting cell types, and a peculiar innervation distribution. Restoring the OC following long-term hearing loss is complicated by the fact that the entire organ is replaced by a flat epithelium and requires reconstructing the organ from uniform undifferentiated cell types, recapitulating both evolution and development. Finding the right sequence of gene activation during development that is useful for regeneration could benefit from an understanding of the OC evolution. Toward this end, we report on Foxg1 and Lmx1a mutants that radically alter the OC cell assembly and its innervation when mutated and may have driven the evolutionary reorganization of the basilar papilla into an OC in ancestral Therapsids. Furthermore, genetically manipulating the level of bHLH TFs changes HC type and distribution and allows inference how transformation of HCs might have happened evolutionarily. We report on how bHLH TFs regulate OHC/IHC and how misexpression (Atoh1-Cre; Atoh1f/kiNeurog1) alters HC fate and supporting cell development. Using mice with altered HC types and distribution, we demonstrate innervation changes driven by HC patterning. Using these insights, we speculate on necessary steps needed to convert a random mixture of post-mitotic precursors into the orderly OC through spatially and temporally regulated critical bHLH genes in the context of other TFs to restore normal innervation patterns.
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Affiliation(s)
- Israt Jahan
- Department of Biology, University of Iowa, 129 East Jefferson, Iowa City, IA 52242, USA
| | - Karen L Elliott
- Department of Biology, University of Iowa, 129 East Jefferson, Iowa City, IA 52242, USA
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, 129 East Jefferson, Iowa City, IA 52242, USA
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31
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Booth KT, Azaiez H, Jahan I, Smith RJH, Fritzsch B. Intracellular Regulome Variability Along the Organ of Corti: Evidence, Approaches, Challenges, and Perspective. Front Genet 2018; 9:156. [PMID: 29868110 PMCID: PMC5951964 DOI: 10.3389/fgene.2018.00156] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 04/13/2018] [Indexed: 12/13/2022] Open
Abstract
The mammalian hearing organ is a regular array of two types of hair cells (HCs) surrounded by six types of supporting cells. Along the tonotopic axis, this conserved radial array of cell types shows longitudinal variations to enhance the tuning properties of basilar membrane. We present the current evidence supporting the hypothesis that quantitative local variations in gene expression profiles are responsible for local cell responses to global gene manipulations. With the advent of next generation sequencing and the unprecedented array of technologies offering high throughput analyses at the single cell level, transcriptomics will become a common tool to enhance our understanding of the inner ear. We provide an overview of the approaches and landmark studies undertaken to date to analyze single cell variations in the organ of Corti and discuss the current limitations. We next provide an overview of the complexity of known regulatory mechanisms in the inner ear. These mechanisms are tightly regulated temporally and spatially at the transcription, RNA-splicing, mRNA-regulation, and translation levels. Understanding the intricacies of regulatory mechanisms at play in the inner ear will require the use of complementary approaches, and most probably, a combinatorial strategy coupling transcriptomics, proteomics, and epigenomics technologies. We highlight how these data, in conjunction with recent insights into molecular cell transformation, can advance attempts to restore lost hair cells.
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Affiliation(s)
- Kevin T Booth
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa, Iowa City, IA, United States.,Interdisciplinary Graduate Program in Molecular Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - Hela Azaiez
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa, Iowa City, IA, United States
| | - Israt Jahan
- Department of Biology, University of Iowa, Iowa City, IA, United States
| | - Richard J H Smith
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa, Iowa City, IA, United States
| | - Bernd Fritzsch
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, University of Iowa, Iowa City, IA, United States.,Department of Biology, University of Iowa, Iowa City, IA, United States
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32
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Spatiotemporal coordination of cellular differentiation and tissue morphogenesis in organ of Corti development. Med Mol Morphol 2018. [PMID: 29536272 DOI: 10.1007/s00795-018-0185-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The organ of Corti, an acoustic sensory organ, is a specifically differentiated epithelium of the cochlear duct, which is a part of the membranous labyrinth in the inner ear. Cells in the organ of Corti are generally classified into two kinds; hair cells, which transduce the mechanical stimuli of sound to the cell membrane electrical potential differences, and supporting cells. These cells emerge from homogeneous prosensory epithelium through cell fate determination and differentiation. In the organ of Corti organogenesis, cell differentiation and the rearrangement of their position proceed in parallel, resulting in a characteristic alignment of mature hair cells and supporting cells. Recently, studies have focused on the signaling molecules and transcription factors that regulate cell fate determination and differentiation processes. In comparison, less is known about the mechanism of the formation of the tissue architecture; however, this is important in the morphogenesis of the organ of Corti. Thus, this review will introduce previous findings that focus on how cell fate determination, cell differentiation, and whole tissue morphogenesis proceed in a spatiotemporally and finely coordinated manner. This overview provides an insight into the regulatory mechanisms of the coordination in the developing organ of Corti.
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33
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Matsuoka AJ, Sayed ZA, Stephanopoulos N, Berns EJ, Wadhwani AR, Morrissey ZD, Chadly DM, Kobayashi S, Edelbrock AN, Mashimo T, Miller CA, McGuire TL, Stupp SI, Kessler JA. Creating a stem cell niche in the inner ear using self-assembling peptide amphiphiles. PLoS One 2017; 12:e0190150. [PMID: 29284013 PMCID: PMC5746215 DOI: 10.1371/journal.pone.0190150] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 12/09/2017] [Indexed: 11/23/2022] Open
Abstract
The use of human embryonic stem cells (hESCs) for regeneration of the spiral ganglion will require techniques for promoting otic neuronal progenitor (ONP) differentiation, anchoring of cells to anatomically appropriate and specific niches, and long-term cell survival after transplantation. In this study, we used self-assembling peptide amphiphile (PA) molecules that display an IKVAV epitope (IKVAV-PA) to create a niche for hESC-derived ONPs that supported neuronal differentiation and survival both in vitro and in vivo after transplantation into rodent inner ears. A feature of the IKVAV-PA gel is its ability to form organized nanofibers that promote directed neurite growth. Culture of hESC-derived ONPs in IKVAV-PA gels did not alter cell proliferation or viability. However, the presence of IKVAV-PA gels increased the number of cells expressing the neuronal marker beta-III tubulin and improved neurite extension. The self-assembly properties of the IKVAV-PA gel allowed it to be injected as a liquid into the inner ear to create a biophysical niche for transplanted cells after gelation in vivo. Injection of ONPs combined with IKVAV-PA into the modiolus of X-SCID rats increased survival and localization of the cells around the injection site compared to controls. Human cadaveric temporal bone studies demonstrated the technical feasibility of a transmastoid surgical approach for clinical intracochlear injection of the IKVAV-PA/ONP combination. Combining stem cell transplantation with injection of self-assembling PA gels to create a supportive niche may improve clinical approaches to spiral ganglion regeneration.
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Affiliation(s)
- Akihiro J. Matsuoka
- Department of Otolaryngology and Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- Department of Communication Sciences and Disorders, Northwestern University, Evanston, Illinois, United States of America
- Hugh Knowles Center for Hearing Research, Northwestern University, Evanston, Illinois, United States of America
- * E-mail:
| | - Zafar A. Sayed
- Department of Otolaryngology and Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Nicholas Stephanopoulos
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, Illinois, United States of America
| | - Eric J. Berns
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
| | - Anil R. Wadhwani
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Zachery D. Morrissey
- Department of Otolaryngology and Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Duncan M. Chadly
- Department of Otolaryngology and Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Shun Kobayashi
- Department of Otolaryngology and Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Alexandra N. Edelbrock
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
| | - Tomoji Mashimo
- The Institute of Experimental Animal Sciences, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Charles A. Miller
- Department of Otolaryngology and Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Tammy L. McGuire
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Samuel I. Stupp
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, Illinois, United States of America
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- Department of Chemistry, Northwestern University, Evanston, Illinois, United States of America
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States of America
| | - John A. Kessler
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
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34
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Chen Y, Lu X, Guo L, Ni W, Zhang Y, Zhao L, Wu L, Sun S, Zhang S, Tang M, Li W, Chai R, Li H. Hedgehog Signaling Promotes the Proliferation and Subsequent Hair Cell Formation of Progenitor Cells in the Neonatal Mouse Cochlea. Front Mol Neurosci 2017; 10:426. [PMID: 29311816 PMCID: PMC5742997 DOI: 10.3389/fnmol.2017.00426] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 12/06/2017] [Indexed: 12/11/2022] Open
Abstract
Hair cell (HC) loss is the major cause of permanent sensorineural hearing loss in mammals. Unlike lower vertebrates, mammalian cochlear HCs cannot regenerate spontaneously after damage, although the vestibular system does maintain limited HC regeneration capacity. Thus HC regeneration from the damaged sensory epithelium has been one of the main areas of research in the field of hearing restoration. Hedgehog signaling plays important roles during the embryonic development of the inner ear, and it is involved in progenitor cell proliferation and differentiation as well as the cell fate decision. In this study, we show that recombinant Sonic Hedgehog (Shh) protein effectively promotes sphere formation, proliferation, and differentiation of Lgr5+ progenitor cells isolated from the neonatal mouse cochlea. To further explore this, we determined the effect of Hedgehog signaling on cell proliferation and HC regeneration in cultured cochlear explant from transgenic R26-SmoM2 mice that constitutively activate Hedgehog signaling in the supporting cells of the cochlea. Without neomycin treatment, up-regulation of Hedgehog signaling did not significantly promote cell proliferation or new HC formation. However, after injury to the sensory epithelium by neomycin treatment, the over-activation of Hedgehog signaling led to significant supporting cell proliferation and HC regeneration in the cochlear epithelium explants. RNA sequencing and real-time PCR were used to compare the transcripts of the cochleae from control mice and R26-SmoM2 mice, and multiple genes involved in the proliferation and differentiation processes were identified. This study has important implications for the treatment of sensorineural hearing loss by manipulating the Hedgehog signaling pathway.
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Affiliation(s)
- Yan Chen
- 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 of National Health and Family Planning Commission (NHFPC), Shanghai, China
| | - Xiaoling Lu
- 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 of National Health and Family Planning Commission (NHFPC), Shanghai, China
| | - Luo Guo
- 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 of National Health and Family Planning Commission (NHFPC), Shanghai, China
| | - Wenli Ni
- 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 of National Health and Family Planning Commission (NHFPC), Shanghai, China
| | - Yanping Zhang
- 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 of National Health and Family Planning Commission (NHFPC), Shanghai, China
| | - Liping Zhao
- 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 of National Health and Family Planning Commission (NHFPC), Shanghai, China
| | - Lingjie Wu
- 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 of National Health and Family Planning Commission (NHFPC), Shanghai, China
| | - Shan Sun
- 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 of National Health and Family Planning Commission (NHFPC), Shanghai, China
| | - Shasha Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Mingliang Tang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, China
| | - Wenyan Li
- 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 of National Health and Family Planning Commission (NHFPC), Shanghai, China
| | - Renjie Chai
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University, Nanjing, China.,Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Huawei Li
- 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 of National Health and Family Planning Commission (NHFPC), Shanghai, China.,Institutes of Biomedical Sciences, Fudan University, Shanghai, China.,The Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China.,Shanghai Engineering Research Centre of Cochlear Implant, Shanghai, China
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35
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Gálvez H, Tena JJ, Giraldez F, Abelló G. The Repression of Atoh1 by Neurogenin1 during Inner Ear Development. Front Mol Neurosci 2017; 10:321. [PMID: 29104531 PMCID: PMC5655970 DOI: 10.3389/fnmol.2017.00321] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 09/21/2017] [Indexed: 01/01/2023] Open
Abstract
Atonal homolog 1 (Atoh1) and Neurogenin1 (Neurog1) are basic Helix-Loop-Helix (bHLH) transcription factors crucial for the generation of hair cells (HCs) and neurons in the inner ear. Both genes are induced early in development, but the expression of Atoh1 is counteracted by Neurog1. As a result, HC development is prevented during neurogenesis. This work aimed at understanding the molecular basis of this interaction. Atoh1 regulation depends on a 3'Atoh1-enhancer that is the site for Atoh1 autoregulation. Reporter assays on chick embryos and P19 cells show that Neurog1 hampers the autoactivation of Atoh1, the effect being cell autonomous and independent on Notch activity. Assay for Transposase-Accessible Chromatin with high throughput sequencing (ATAC-Seq) analysis shows that the region B of the 3'Atoh1-enhancer is accessible during development and sufficient for both activation and repression. Neurog1 requires the regions flanking the class A E-box to show its repressor effect, however, it does not require binding to DNA for Atoh1 repression. This depends on the dimerization domains Helix-1 and Helix-2 and the reduction of Atoh1 protein levels. The results point towards the acceleration of Atoh1 mRNA degradation as the potential mechanism for the reduction of Atoh1 levels. Such a mechanism dissociates the prevention of Atoh1 expression in neurosensory progenitors from the unfolding of the neurogenic program.
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Affiliation(s)
- Héctor Gálvez
- DCEXS, Universitat Pompeu Fabra (UPF) - Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain
| | - Juan J Tena
- Centro Andaluz de Biología del Desarrollo, Consejo Superior de Investigaciones Científicas (CSIC), Sevilla, Spain
| | - Fernando Giraldez
- DCEXS, Universitat Pompeu Fabra (UPF) - Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain
| | - Gina Abelló
- DCEXS, Universitat Pompeu Fabra (UPF) - Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain
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36
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NEUROG1 Regulates CDK2 to Promote Proliferation in Otic Progenitors. Stem Cell Reports 2017; 9:1516-1529. [PMID: 29033307 PMCID: PMC5829327 DOI: 10.1016/j.stemcr.2017.09.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 09/13/2017] [Accepted: 09/14/2017] [Indexed: 12/23/2022] Open
Abstract
Loss of spiral ganglion neurons (SGNs) significantly contributes to hearing loss. Otic progenitor cell transplantation is a potential strategy to replace lost SGNs. Understanding how key transcription factors promote SGN differentiation in otic progenitors accelerates efforts for replacement therapies. A pro-neural transcription factor, Neurogenin1 (Neurog1), is essential for SGN development. Using an immortalized multipotent otic progenitor (iMOP) cell line that can self-renew and differentiate into otic neurons, NEUROG1 was enriched at the promoter of cyclin-dependent kinase 2 (Cdk2) and neurogenic differentiation 1 (NeuroD1) genes. Changes in H3K9ac and H3K9me3 deposition at the Cdk2 and NeuroD1 promoters suggested epigenetic regulation during iMOP proliferation and differentiation. In self-renewing iMOP cells, overexpression of NEUROG1 increased CDK2 to drive proliferation, while knockdown of NEUROG1 decreased CDK2 and reduced proliferation. In iMOP-derived neurons, overexpression of NEUROG1 accelerated acquisition of neuronal morphology, while knockdown of NEUROG1 prevented differentiation. Our findings suggest that NEUROG1 can promote proliferation or neuronal differentiation.
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Fritzsch B, Elliott KL. Gene, cell, and organ multiplication drives inner ear evolution. Dev Biol 2017; 431:3-15. [PMID: 28866362 DOI: 10.1016/j.ydbio.2017.08.034] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 04/27/2017] [Accepted: 08/25/2017] [Indexed: 12/14/2022]
Abstract
We review the development and evolution of the ear neurosensory cells, the aggregation of neurosensory cells into an otic placode, the evolution of novel neurosensory structures dedicated to hearing and the evolution of novel nuclei in the brain and their input dedicated to processing those novel auditory stimuli. The evolution of the apparently novel auditory system lies in duplication and diversification of cell fate transcription regulation that allows variation at the cellular level [transforming a single neurosensory cell into a sensory cell connected to its targets by a sensory neuron as well as diversifying hair cells], organ level [duplication of organ development followed by diversification and novel stimulus acquisition] and brain nuclear level [multiplication of transcription factors to regulate various neuron and neuron aggregate fate to transform the spinal cord into the unique hindbrain organization]. Tying cell fate changes driven by bHLH and other transcription factors into cell and organ changes is at the moment tentative as not all relevant factors are known and their gene regulatory network is only rudimentary understood. Future research can use the blueprint proposed here to provide both the deeper molecular evolutionary understanding as well as a more detailed appreciation of developmental networks. This understanding can reveal how an auditory system evolved through transformation of existing cell fate determining networks and thus how neurosensory evolution occurred through molecular changes affecting cell fate decision processes. Appreciating the evolutionary cascade of developmental program changes could allow identifying essential steps needed to restore cells and organs in the future.
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Affiliation(s)
- Bernd Fritzsch
- University of Iowa, Department of Biology, Iowa City, IA 52242, United States.
| | - Karen L Elliott
- University of Iowa, Department of Biology, Iowa City, IA 52242, United States
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38
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Modrell MS, Lyne M, Carr AR, Zakon HH, Buckley D, Campbell AS, Davis MC, Micklem G, Baker CV. Insights into electrosensory organ development, physiology and evolution from a lateral line-enriched transcriptome. eLife 2017; 6. [PMID: 28346141 PMCID: PMC5429088 DOI: 10.7554/elife.24197] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 03/23/2017] [Indexed: 01/22/2023] Open
Abstract
The anamniote lateral line system, comprising mechanosensory neuromasts and electrosensory ampullary organs, is a useful model for investigating the developmental and evolutionary diversification of different organs and cell types. Zebrafish neuromast development is increasingly well understood, but neither zebrafish nor Xenopus is electroreceptive and our molecular understanding of ampullary organ development is rudimentary. We have used RNA-seq to generate a lateral line-enriched gene-set from late-larval paddlefish (Polyodon spathula). Validation of a subset reveals expression in developing ampullary organs of transcription factor genes critical for hair cell development, and genes essential for glutamate release at hair cell ribbon synapses, suggesting close developmental, physiological and evolutionary links between non-teleost electroreceptors and hair cells. We identify an ampullary organ-specific proneural transcription factor, and candidates for the voltage-sensing L-type Cav channel and rectifying Kv channel predicted from skate (cartilaginous fish) ampullary organ electrophysiology. Overall, our results illuminate ampullary organ development, physiology and evolution.
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Affiliation(s)
- Melinda S Modrell
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Mike Lyne
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom.,Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Adrian R Carr
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom.,Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Harold H Zakon
- Department of Neuroscience, The University of Texas at Austin, Austin, United States.,Department of Integrative Biology, The University of Texas at Austin, Austin, United States
| | - David Buckley
- Departmento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales-MNCN-CSIC, Madrid, Spain.,Department of Natural Sciences, Saint Louis University - Madrid Campus, Madrid, Spain
| | - Alexander S Campbell
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Marcus C Davis
- Department of Molecular and Cellular Biology, Kennesaw State University, Kennesaw, United States
| | - Gos Micklem
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom.,Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Clare Vh Baker
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
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Gálvez H, Abelló G, Giraldez F. Signaling and Transcription Factors during Inner Ear Development: The Generation of Hair Cells and Otic Neurons. Front Cell Dev Biol 2017; 5:21. [PMID: 28393066 PMCID: PMC5364141 DOI: 10.3389/fcell.2017.00021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 03/02/2017] [Indexed: 12/21/2022] Open
Abstract
Integration between cell signals and bHLH transcription factors plays a prominent role during the development of hair cells of the inner ear. Hair cells are the sensory receptors of the inner ear, responsible for the mechano-transduction of sound waves into electrical signals. They derive from multipotent progenitors that reside in the otic placode. Progenitor commitment is the result of cell signaling from the surrounding tissues that result in the restricted expression of SoxB1 transcription factors, Sox2 and Sox3. In turn, they induce the expression of Neurog1 and Atoh1, two bHLH factors that specify neuronal and hair cell fates, respectively. Neuronal and hair cell development, however, do not occur simultaneously. Hair cell development is prevented during neurogenesis and prosensory stages, resulting in the delay of hair cell development with respect to neuron production. Negative interactions between Neurog1 and Atoh1, and of Atoh1 with other bHLH factors driven by Notch signaling, like Hey1 and Hes5, account for this delay. In summary, the regulation of Atoh1 and hair cell development relies on interactions between cell signaling and bHLH transcription factors that dictate cell fate and timing decisions during development. Interestingly, these mechanisms operate as well during hair cell regeneration after damage and during stem cell directed differentiation, making developmental studies instrumental for improving therapies for hearing impairment.
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Affiliation(s)
- Héctor Gálvez
- Developmental Biology, CEXS, Parc de Recerca Biomèdica de Barcelona, Universitat Pompeu Fabra Barcelona, Spain
| | - Gina Abelló
- Developmental Biology, CEXS, Parc de Recerca Biomèdica de Barcelona, Universitat Pompeu Fabra Barcelona, Spain
| | - Fernando Giraldez
- Developmental Biology, CEXS, Parc de Recerca Biomèdica de Barcelona, Universitat Pompeu Fabra Barcelona, Spain
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Mellott AJ, Shinogle HE, Nelson-Brantley JG, Detamore MS, Staecker H. Exploiting decellularized cochleae as scaffolds for inner ear tissue engineering. Stem Cell Res Ther 2017; 8:41. [PMID: 28241887 PMCID: PMC5330011 DOI: 10.1186/s13287-017-0505-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 01/18/2017] [Accepted: 02/10/2017] [Indexed: 11/20/2022] Open
Abstract
Background Use of decellularized tissues has become popular in tissue engineering applications as the natural extracellular matrix can provide necessary physical cues that help induce the restoration and development of functional tissues. In relation to cochlear tissue engineering, the question of whether decellularized cochlear tissue can act as a scaffold and support the incorporation of exogenous cells has not been addressed. Investigators have explored the composition of the cochlear extracellular matrix and developed multiple strategies for decellularizing a variety of different tissues; however, no one has investigated whether decellularized cochlear tissue can support implantation of exogenous cells. Methods As a proof-of-concept study, human Wharton’s jelly cells were perfused into decellularized cochleae isolated from C57BL/6 mice to determine if human Wharton’s jelly cells could implant into decellularized cochlear tissue. Decellularization was verified through scanning electron microscopy. Cocheae were stained with DAPI and immunostained with Myosin VIIa to identify cells. Perfused cochleae were imaged using confocal microscopy. Results Features of the organ of Corti were clearly identified in the native cochleae when imaged with scanning electron microscopy and confocal microscopy. Acellular structures were identified in decellularized cochleae; however, no cellular structures or lipid membranes were present within the decellularized cochleae when imaged via scanning electron microscopy. Confocal microscopy revealed positive identification and adherence of cells in decellularized cochleae after perfusion with human Wharton’s jelly cells. Some cells positively expressed Myosin VIIa after perfusion. Conclusions Human Wharton’s jelly cells are capable of successfully implanting into decellularized cochlear extracellular matrix. The identification of Myosin VIIa expression in human Wharton’s jelly cells after implantation into the decellularized cochlear extracellular matrix suggest that components of the cochlear extracellular matrix may be involved in differentiation.
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Affiliation(s)
- Adam J Mellott
- Department of Plastic Surgery, University of Kansas Medical Center, Kansas City, KS, 66160, USA
| | - Heather E Shinogle
- Microscopy and Analytical Imaging Laboratory, University of Kansas, Lawrence, KS, 66045, USA
| | - Jennifer G Nelson-Brantley
- Department of Otolaryngology, Head and Neck Surgery, University of Kansas Medical Center, 3901 Rainbow Blvd, MS 3010, Kansas City, KS, 66160, USA
| | - Michael S Detamore
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK, 73019, USA
| | - Hinrich Staecker
- Department of Otolaryngology, Head and Neck Surgery, University of Kansas Medical Center, 3901 Rainbow Blvd, MS 3010, Kansas City, KS, 66160, USA.
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Dvorakova M, Jahan I, Macova I, Chumak T, Bohuslavova R, Syka J, Fritzsch B, Pavlinkova G. Incomplete and delayed Sox2 deletion defines residual ear neurosensory development and maintenance. Sci Rep 2016; 6:38253. [PMID: 27917898 PMCID: PMC5137136 DOI: 10.1038/srep38253] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 11/07/2016] [Indexed: 11/09/2022] Open
Abstract
The role of Sox2 in neurosensory development is not yet fully understood. Using mice with conditional Islet1-cre mediated deletion of Sox2, we explored the function of Sox2 in neurosensory development in a model with limited cell type diversification, the inner ear. In Sox2 conditional mutants, neurons initially appear to form normally, whereas late- differentiating neurons of the cochlear apex never form. Variable numbers of hair cells differentiate in the utricle, saccule, and cochlear base but sensory epithelium formation is completely absent in the apex and all three cristae of the semicircular canal ampullae. Hair cells differentiate only in sensory epithelia known or proposed to have a lineage relationship of neurons and hair cells. All initially formed neurons lacking hair cell targets die by apoptosis days after they project toward non-existing epithelia. Therefore, late neuronal development depends directly on Sox2 for differentiation and on the survival of hair cells, possibly derived from common neurosensory precursors.
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Affiliation(s)
- Martina Dvorakova
- Institute of Biotechnology CAS, Prague, Czechia
- Faculty of Science, Charles University, Prague, Czechia
| | - Israt Jahan
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - Iva Macova
- Institute of Biotechnology CAS, Prague, Czechia
- Faculty of Science, Charles University, Prague, Czechia
| | | | | | - Josef Syka
- Institute of Experimental Medicine CAS, Prague, Czechia
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, USA
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Żak M, van Oort T, Hendriksen FG, Garcia MI, Vassart G, Grolman W. LGR4 and LGR5 Regulate Hair Cell Differentiation in the Sensory Epithelium of the Developing Mouse Cochlea. Front Cell Neurosci 2016; 10:186. [PMID: 27559308 PMCID: PMC4988241 DOI: 10.3389/fncel.2016.00186] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 07/19/2016] [Indexed: 02/06/2023] Open
Abstract
In the developing cochlea, Wnt/β-catenin signaling positively regulates the proliferation of precursors and promotes the formation of hair cells by up-regulating Atoh1 expression. Not much, however, is known about the regulation of Wnt/β-catenin activity in the cochlea. In multiple tissues, the activity of Wnt/β-catenin signaling is modulated by an interaction between LGR receptors and their ligands from the R-spondin family. The deficiency in Lgr4 and Lgr5 genes leads to developmental malformations and lethality. Using the Lgr5 knock-in mouse line we show that loss of LGR5 function increases Wnt/β-catenin activity in the embryonic cochlea, resulting in a mild overproduction of inner and outer hair cells (OHC). Supernumerary hair cells are likely formed due to an up-regulation of the “pro-hair cell” transcription factors Atoh1, Nhlh1, and Pou4f3. Using a hypomorphic Lgr4 mouse model we showed a mild overproduction of OHCs in the heterozygous and homozygous Lgr4 mice. The loss of LGR4 function prolonged the proliferation in the mid-basal turn of E13 cochleae, causing an increase in the number of SOX2-positive precursor cells within the pro-sensory domain. The premature differentiation of hair cells progressed in a medial to lateral gradient in Lgr4 deficient embryos. No significant up-regulation of Atoh1 was observed following Lgr4 deletion. Altogether, our findings suggest that LGR4 and LGR5 play an important role in the regulation of hair cell differentiation in the embryonic cochlea.
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Affiliation(s)
- Magdalena Żak
- Department of Otorhinolaryngology and Head and Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht Utrecht, Netherlands
| | - Thijs van Oort
- Department of Otorhinolaryngology and Head and Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht Utrecht, Netherlands
| | - Ferry G Hendriksen
- Department of Otorhinolaryngology and Head and Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht Utrecht, Netherlands
| | - Marie-Isabelle Garcia
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Faculty of Medicine, Université Libre de Bruxelles Brussels, Belgium
| | - Gilbert Vassart
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Faculty of Medicine, Université Libre de Bruxelles Brussels, Belgium
| | - Wilko Grolman
- Department of Otorhinolaryngology and Head and Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht Utrecht, Netherlands
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Basch ML, Brown RM, Jen H, Groves AK. Where hearing starts: the development of the mammalian cochlea. J Anat 2016; 228:233-54. [PMID: 26052920 PMCID: PMC4718162 DOI: 10.1111/joa.12314] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2015] [Indexed: 12/11/2022] Open
Abstract
The mammalian cochlea is a remarkable sensory organ, capable of perceiving sound over a range of 10(12) in pressure, and discriminating both infrasonic and ultrasonic frequencies in different species. The sensory hair cells of the mammalian cochlea are exquisitely sensitive, responding to atomic-level deflections at speeds on the order of tens of microseconds. The number and placement of hair cells are precisely determined during inner ear development, and a large number of developmental processes sculpt the shape, size and morphology of these cells along the length of the cochlear duct to make them optimally responsive to different sound frequencies. In this review, we briefly discuss the evolutionary origins of the mammalian cochlea, and then describe the successive developmental processes that lead to its induction, cell cycle exit, cellular patterning and the establishment of topologically distinct frequency responses along its length.
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Affiliation(s)
- Martin L. Basch
- Department of NeuroscienceBaylor College of MedicineHoustonTXUSA
| | - Rogers M. Brown
- Program in Developmental BiologyBaylor College of MedicineHoustonTXUSA
| | - Hsin‐I Jen
- Program in Developmental BiologyBaylor College of MedicineHoustonTXUSA
| | - Andrew K. Groves
- Department of NeuroscienceBaylor College of MedicineHoustonTXUSA
- Program in Developmental BiologyBaylor College of MedicineHoustonTXUSA
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonTXUSA
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Yang T, Scholl ES, Pan N, Fritzsch B, Haeseleer F, Lee A. Expression and Localization of CaBP Ca2+ Binding Proteins in the Mouse Cochlea. PLoS One 2016; 11:e0147495. [PMID: 26809054 PMCID: PMC4725724 DOI: 10.1371/journal.pone.0147495] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 01/05/2016] [Indexed: 11/19/2022] Open
Abstract
CaBPs are a family of EF-hand Ca2+ binding proteins that are structurally similar to calmodulin. CaBPs can interact with, and yet differentially modulate, effectors that are regulated by calmodulin, such as Cav1 voltage-gated Ca2+ channels. Immunolabeling studies suggest that multiple CaBP family members (CaBP1, 2, 4, and 5) are expressed in the cochlea. To gain insights into the respective auditory functions of these CaBPs, we characterized the expression and cellular localization of CaBPs in the mouse cochlea. By quantitative reverse transcription PCR, we show that CaBP1 and CaBP2 are the major CaBPs expressed in mouse cochlea both before and after hearing onset. Of the three alternatively spliced variants of CaBP1 (caldendrin, CaBP1-L, and CaBP1-S) and CaBP2 (CaBP2-alt, CaBP2-L, CaBP2-S), caldendrin and CaBP2-alt are the most abundant. By in situ hybridization, probes recognizing caldendrin strongly label the spiral ganglion, while probes designed to recognize all three isoforms of CaBP1 weakly label both the inner and outer hair cells as well as the spiral ganglion. Within the spiral ganglion, caldendrin/CaBP1 labeling is associated with cells resembling satellite glial cells. CaBP2-alt is strongly expressed in inner hair cells both before and after hearing onset. Probes designed to recognize all three variants of CaBP2 strongly label inner hair cells before hearing onset and outer hair cells after the onset of hearing. Thus, CaBP1 and CaBP2 may have overlapping roles in regulating Ca2+ signaling in the hair cells, and CaBP1 may have an additional function in the spiral ganglion. Our findings provide a framework for understanding the role of CaBP family members in the auditory periphery.
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Affiliation(s)
- Tian Yang
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, United States of America
- Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, Iowa, United States of America
- Department of Neurology, University of Iowa, Iowa City, Iowa, United States of America
| | - Elizabeth S. Scholl
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, United States of America
- Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, Iowa, United States of America
- Department of Neurology, University of Iowa, Iowa City, Iowa, United States of America
| | - Ning Pan
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - Bernd Fritzsch
- Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, Iowa, United States of America
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - Françoise Haeseleer
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, United States of America
- Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, Iowa, United States of America
- Department of Neurology, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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45
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Goodrich LV. Early Development of the Spiral Ganglion. THE PRIMARY AUDITORY NEURONS OF THE MAMMALIAN COCHLEA 2016. [DOI: 10.1007/978-1-4939-3031-9_2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Lorenzen SM, Duggan A, Osipovich AB, Magnuson MA, García-Añoveros J. Insm1 promotes neurogenic proliferation in delaminated otic progenitors. Mech Dev 2015; 138 Pt 3:233-45. [PMID: 26545349 DOI: 10.1016/j.mod.2015.11.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 10/02/2015] [Accepted: 11/02/2015] [Indexed: 01/12/2023]
Abstract
INSM1 is a zinc-finger protein expressed throughout the developing nervous system in late neuronal progenitors and nascent neurons. In the embryonic cortex and olfactory epithelium, Insm1 may promote the transition of progenitors from apical, proliferative, and uncommitted to basal, terminally-dividing and neuron producing. In the otocyst, delaminating and delaminated progenitors express Insm1, whereas apically-dividing progenitors do not. This expression pattern is analogous to that in embryonic olfactory epithelium and cortex (basal/subventricular progenitors). Lineage analysis confirms that auditory and vestibular neurons originate from Insm1-expressing cells. In the absence of Insm1, otic ganglia are smaller, with 40% fewer neurons. Accounting for the decrease in neurons, delaminated progenitors undergo fewer mitoses, but there is no change in apoptosis. We conclude that in the embryonic inner ear, Insm1 promotes proliferation of delaminated neuronal progenitors and hence the production of neurons, a similar function to that in other embryonic neural epithelia. Unexpectedly, we also found that differentiating, but not mature, outer hair cells express Insm1, whereas inner hair cells do not. Insm1 is the earliest known gene expressed in outer versus inner hair cells, demonstrating that nascent outer hair cells initiate a unique differentiation program in the embryo, much earlier than previously believed.
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Affiliation(s)
- Sarah M Lorenzen
- Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Anne Duggan
- Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Anna B Osipovich
- Center for Stem Cell Biology, Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Mark A Magnuson
- Center for Stem Cell Biology, Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Jaime García-Añoveros
- Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Departments of Neurology and Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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Jahan I, Pan N, Kersigo J, Fritzsch B. Neurog1 can partially substitute for Atoh1 function in hair cell differentiation and maintenance during organ of Corti development. Development 2015. [PMID: 26209643 DOI: 10.1242/dev.123091] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Atoh1, a basic helix-loop-helix (bHLH) transcription factor (TF), is essential for the differentiation of hair cells (HCs), mechanotransducers that convert sound into auditory signals in the mammalian organ of Corti (OC). Previous work demonstrated that replacing mouse Atoh1 with the fly ortholog atonal rescues HC differentiation, indicating functional replacement by other bHLH genes. However, replacing Atoh1 with Neurog1 resulted in reduced HC differentiation compared with transient Atoh1 expression in a 'self-terminating' Atoh1 conditional null mouse (Atoh1-Cre; Atoh1(f/f)). We now show that combining Neurog1 in one allele with removal of floxed Atoh1 in a self-terminating conditional mutant (Atoh1-Cre; Atoh1(f/kiNeurog1)) mouse results in significantly more differentiated inner HCs and outer HCs that have a prolonged longevity of 9 months compared with Atoh1 self-terminating littermates. Stereocilia bundles are partially disorganized, disoriented and not HC type specific. Replacement of Atoh1 with Neurog1 maintains limited expression of Pou4f3 and Barhl1 and rescues HCs quantitatively, but not qualitatively. OC patterning and supporting cell differentiation are also partially disrupted. Diffusible factors involved in patterning are reduced (Fgf8) and factors involved in cell-cell interactions are affected (Jag1, Hes5). Despite the presence of many HCs with stereocilia these mice are deaf, possibly owing to HC and OC patterning defects. This study provides a novel approach to disrupt OC development through modulating the HC-specific intracellular TF network. The resulting disorganized OC indicates that normally differentiated HCs act as 'self-organizers' for OC development and that Atoh1 plays a crucial role to initiate HC stereocilia differentiation independently of HC viability.
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Affiliation(s)
- Israt Jahan
- Department of Biology, College of Liberal Arts & Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - Ning Pan
- Department of Biology, College of Liberal Arts & Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - Jennifer Kersigo
- Department of Biology, College of Liberal Arts & Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - Bernd Fritzsch
- Department of Biology, College of Liberal Arts & Sciences, University of Iowa, Iowa City, IA 52242, USA
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Jahan I, Pan N, Elliott KL, Fritzsch B. The quest for restoring hearing: Understanding ear development more completely. Bioessays 2015. [PMID: 26208302 DOI: 10.1002/bies.201500044] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Neurosensory hearing loss is a growing problem of super-aged societies. Cochlear implants can restore some hearing, but rebuilding a lost hearing organ would be superior. Research has discovered many cellular and molecular steps to develop a hearing organ but translating those insights into hearing organ restoration remains unclear. For example, we cannot make various hair cell types and arrange them into their specific patterns surrounded by the right type of supporting cells in the right numbers. Our overview of the topologically highly organized and functionally diversified cellular mosaic of the mammalian hearing organ highlights what is known and unknown about its development. Following this analysis, we suggest critical steps to guide future attempts toward restoration of a functional organ of Corti. We argue that generating mutant mouse lines that mimic human pathology to fine-tune attempts toward long-term functional restoration are needed to go beyond the hope generated by restoring single hair cells in postnatal sensory epithelia.
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Affiliation(s)
- Israt Jahan
- Department of Biology, CLAS, University of Iowa, Iowa City, IA, USA
| | - Ning Pan
- Department of Biology, CLAS, University of Iowa, Iowa City, IA, USA
| | - Karen L Elliott
- Department of Biology, CLAS, University of Iowa, Iowa City, IA, USA
| | - Bernd Fritzsch
- Department of Biology, CLAS, University of Iowa, Iowa City, IA, USA
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Atkinson PJ, Huarcaya Najarro E, Sayyid ZN, Cheng AG. Sensory hair cell development and regeneration: similarities and differences. Development 2015; 142:1561-71. [PMID: 25922522 DOI: 10.1242/dev.114926] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Sensory hair cells are mechanoreceptors of the auditory and vestibular systems and are crucial for hearing and balance. In adult mammals, auditory hair cells are unable to regenerate, and damage to these cells results in permanent hearing loss. By contrast, hair cells in the chick cochlea and the zebrafish lateral line are able to regenerate, prompting studies into the signaling pathways, morphogen gradients and transcription factors that regulate hair cell development and regeneration in various species. Here, we review these findings and discuss how various signaling pathways and factors function to modulate sensory hair cell development and regeneration. By comparing and contrasting development and regeneration, we also highlight the utility and limitations of using defined developmental cues to drive mammalian hair cell regeneration.
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Affiliation(s)
- Patrick J Atkinson
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Elvis Huarcaya Najarro
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Zahra N Sayyid
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alan G Cheng
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
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Fritzsch B, Pan N, Jahan I, Elliott KL. Inner ear development: building a spiral ganglion and an organ of Corti out of unspecified ectoderm. Cell Tissue Res 2015; 361:7-24. [PMID: 25381571 PMCID: PMC4426086 DOI: 10.1007/s00441-014-2031-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 10/09/2014] [Indexed: 01/21/2023]
Abstract
The mammalian inner ear develops from a placodal thickening into a complex labyrinth of ducts with five sensory organs specialized to detect position and movement in space. The mammalian ear also develops a spiraled cochlear duct containing the auditory organ, the organ of Corti (OC), specialized to translate sound into hearing. Development of the OC from a uniform sheet of ectoderm requires unparalleled precision in the topological developmental engineering of four different general cell types, namely sensory neurons, hair cells, supporting cells, and general otic epithelium, into a mosaic of ten distinctly recognizable cell types in and around the OC, each with a unique distribution. Moreover, the OC receives unique innervation by ear-derived spiral ganglion afferents and brainstem-derived motor neurons as efferents and requires neural-crest-derived Schwann cells to form myelin and neural-crest-derived cells to induce the stria vascularis. This transformation of a sheet of cells into a complicated interdigitating set of cells necessitates the orchestrated expression of multiple transcription factors that enable the cellular transformation from ectoderm into neurosensory cells forming the spiral ganglion neurons (SGNs), while simultaneously transforming the flat epithelium into a tube, the cochlear duct, housing the OC. In addition to the cellular and conformational changes forming the cochlear duct with the OC, changes in the surrounding periotic mesenchyme form passageways for sound to stimulate the OC. We review molecular developmental data, generated predominantly in mice, in order to integrate the well-described expression changes of transcription factors and their actions, as revealed in mutants, in the formation of SGNs and OC in the correct position and orientation with suitable innervation. Understanding the molecular basis of these developmental changes leading to the formation of the mammalian OC and highlighting the gaps in our knowledge might guide in vivo attempts to regenerate this most complicated cellular mosaic of the mammalian body for the reconstitution of hearing in a rapidly growing population of aging people suffering from hearing loss.
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Affiliation(s)
- Bernd Fritzsch
- College of Liberal Arts and Sciences, Department of Biology, University of Iowa, 143 BB, 123 Jefferson Avenue, Iowa City, IA 52242, USA,
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