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Qiu Y, Xie L, Wang X, Xu K, Bai X, Chen S, Sun Y. Abnormal Innervation, Demyelination, and Degeneration of Spiral Ganglion Neurons as Well as Disruption of Heminodes are Involved in the Onset of Deafness in Cx26 Null Mice. Neurosci Bull 2024; 40:1093-1103. [PMID: 38311706 PMCID: PMC11306449 DOI: 10.1007/s12264-023-01167-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Accepted: 09/14/2023] [Indexed: 02/06/2024] Open
Abstract
GJB2 gene mutations are the most common causes of autosomal recessive non-syndromic hereditary deafness. For individuals suffering from severe to profound GJB2-related deafness, cochlear implants have emerged as the sole remedy for auditory improvement. Some previous studies have highlighted the crucial role of preserving cochlear neural components in achieving favorable outcomes after cochlear implantation. Thus, we generated a conditional knockout mouse model (Cx26-CKO) in which Cx26 was completely deleted in the cochlear supporting cells driven by the Sox2 promoter. The Cx26-CKO mice showed severe hearing loss and massive loss of hair cells and Deiter's cells, which represented the extreme form of human deafness caused by GJB2 gene mutations. In addition, multiple pathological changes in the peripheral auditory nervous system were found, including abnormal innervation, demyelination, and degeneration of spiral ganglion neurons as well as disruption of heminodes in Cx26-CKO mice. These findings provide invaluable insights into the deafness mechanism and the treatment for severe deafness in Cx26-null mice.
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Affiliation(s)
- Yue Qiu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Le Xie
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Xiaohui Wang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Kai Xu
- Department of Otolaryngology, Nanchang University, Nanchang, 330006, China
| | - Xue Bai
- Department of Otolaryngology, Nanchang University, Nanchang, 330006, China
| | - Sen Chen
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
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Generation of p27icreER transgenic mice: A tool for inducible gene expression in supporting cells in the cochlea. Hear Res 2023; 431:108727. [PMID: 36905855 DOI: 10.1016/j.heares.2023.108727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 02/21/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023]
Abstract
The loss of cochlear hair cells (HCs) is an important cause of sensorineural hearing loss, and finding ways to regenerate HCs would be the ideal way forward for restoring hearing. In this research field, tamoxifen-inducible Cre recombinase (iCreER) transgenic mice and the Cre-loxp system are widely used to manipulate gene expression in supporting cells (SCs), which lie beneath the sensory HCs and are a natural source for HC regeneration. However, many iCreER transgenic lines are of limited utility because they cannot target all subtypes of SCs or they cannot be used in the adult stage. In this study, a new line of iCreER transgenic mice, the p27-P2A-iCreERT2 knock-in mouse strain, was generated by inserting the P2A-iCreERT2 cassette immediately in front of the stop codon of p27, which kept the endogenous expression and function of p27 intact. Using a reporter mouse line with tdTomato fluorescence, we showed that the p27iCreER transgenic line can target all subtypes of cochlear SCs, including Claudius cells. p27-CreER activity in SCs was observed in both the postnatal and the adult stage, suggesting that this mouse strain can be useful for research work in adult cochlear HC regeneration. We then overexpressed Gfi1, Pou4f3, and Atoh1 in p27+ SCs of P6/7 mice using this strain and successfully induced many new Myo7a/tdTomato double-positive cells, further confirming that the p27-P2A-iCreERT2 mouse strain is a new and reliable tool for cochlear HC regeneration and hearing restoration.
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3
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Huang J, Sun X, Wang H, Chen R, Yang Y, Hu J, Zhang Y, Gui F, Huang J, Yang L, Hong Y. Conditional overexpression of neuritin in supporting cells (SCs) mitigates hair cell (HC) damage and induces HC regeneration in the adult mouse cochlea after drug-induced ototoxicity. Hear Res 2022; 420:108515. [DOI: 10.1016/j.heares.2022.108515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 05/03/2022] [Accepted: 05/07/2022] [Indexed: 11/04/2022]
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Rai V, Tu S, Frank JR, Zuo J. Molecular Pathways Modulating Sensory Hair Cell Regeneration in Adult Mammalian Cochleae: Progress and Perspectives. Int J Mol Sci 2021; 23:ijms23010066. [PMID: 35008497 PMCID: PMC8745006 DOI: 10.3390/ijms23010066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/20/2021] [Accepted: 12/20/2021] [Indexed: 12/30/2022] Open
Abstract
Noise-induced, drug-related, and age-related disabling hearing loss is a major public health problem and affect approximately 466 million people worldwide. In non-mammalian vertebrates, the death of sensory hair cells (HCs) induces the proliferation and transdifferentiation of adjacent supporting cells into new HCs; however, this capacity is lost in juvenile and adult mammalian cochleae leading to permanent hearing loss. At present, cochlear implants and hearing devices are the only available treatments and can help patients to a certain extent; however, no biological approach or FDA-approved drug is effective to treat disabling hearing loss and restore hearing. Recently, regeneration of mammalian cochlear HCs by modulating molecular pathways or transcription factors has offered some promising results, although the immaturity of the regenerated HCs remains the biggest concern. Furthermore, most of the research done is in neonates and not in adults. This review focuses on critically summarizing the studies done in adult mammalian cochleae and discusses various strategies to elucidate novel transcription factors for better therapeutics.
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Affiliation(s)
| | | | | | - Jian Zuo
- Correspondence: ; Tel.: +1-(402)-280-2916
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5
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Xu Z, Rai V, Zuo J. TUB and ZNF532 Promote the Atoh1-Mediated Hair Cell Regeneration in Mouse Cochleae. Front Cell Neurosci 2021; 15:759223. [PMID: 34819838 PMCID: PMC8606527 DOI: 10.3389/fncel.2021.759223] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 10/15/2021] [Indexed: 12/31/2022] Open
Abstract
Hair cell (HC) regeneration is a promising therapy for permanent sensorineural hearing loss caused by HC loss in mammals. Atoh1 has been shown to convert supporting cells (SCs) to HCs in neonatal cochleae; its combinations with other factors can improve the efficiency of HC regeneration. To identify additional transcription factors for efficient Atoh1-mediated HC regeneration, here we optimized the electroporation procedure for explant culture of neonatal mouse organs of Corti and tested multiple transcription factors, Six2, Ikzf2, Lbh, Arid3b, Hmg20 a, Tub, Sall1, and Znf532, for their potential to promote Atoh1-mediated conversion of SCs to HCs. These transcription factors are expressed highly in HCs but differentially compared to the converted HCs based on previous studies, and are also potential co-reprograming factors for Atoh1-mediated SC-to-HC conversion by literature review. P0.5 cochlear explants were electroporated with these transcription factors alone or jointly with Atoh1. We found that Sox2+ progenitors concentrated within the lateral greater epithelial ridge (GER) can be electroporated efficiently with minimal HC damage. Atoh1 ectopic expression promoted HC regeneration in Sox2+ lateral GER cells. Transcription factors Tub and Znf532, but not the other six tested, promoted the HC regeneration mediated by Atoh1, consistent with previous studies that Isl1 promotes Atoh1-mediated HC conversionex vivo and in vivo and that both Tub and Znf532 are downstream targets of Isl1. Thus, our studies revealed an optimized electroporation method that can transfect the Sox2+ lateral GER cells efficiently with minimal damage to the endogenous HCs. Our results also demonstrate the importance of the Isl1/Tub/Znf532 pathway in promoting Atoh1-mediated HC regeneration.
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Affiliation(s)
- Zhenhang Xu
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States.,Department of Otolaryngology, Xiangya Hospital, Central South University, Changsha, China
| | - Vikrant Rai
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States
| | - Jian Zuo
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, United States
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Milon B, Shulman ED, So KS, Cederroth CR, Lipford EL, Sperber M, Sellon JB, Sarlus H, Pregernig G, Shuster B, Song Y, Mitra S, Orvis J, Margulies Z, Ogawa Y, Shults C, Depireux DA, Palermo AT, Canlon B, Burns J, Elkon R, Hertzano R. A cell-type-specific atlas of the inner ear transcriptional response to acoustic trauma. Cell Rep 2021; 36:109758. [PMID: 34592158 PMCID: PMC8709734 DOI: 10.1016/j.celrep.2021.109758] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 07/29/2021] [Accepted: 09/03/2021] [Indexed: 01/26/2023] Open
Abstract
Noise-induced hearing loss (NIHL) results from a complex interplay of damage to the sensory cells of the inner ear, dysfunction of its lateral wall, axonal retraction of type 1C spiral ganglion neurons, and activation of the immune response. We use RiboTag and single-cell RNA sequencing to survey the cell-type-specific molecular landscape of the mouse inner ear before and after noise trauma. We identify induction of the transcription factors STAT3 and IRF7 and immune-related genes across all cell-types. Yet, cell-type-specific transcriptomic changes dominate the response. The ATF3/ATF4 stress-response pathway is robustly induced in the type 1A noise-resilient neurons, potassium transport genes are downregulated in the lateral wall, mRNA metabolism genes are downregulated in outer hair cells, and deafness-associated genes are downregulated in most cell types. This transcriptomic resource is available via the Gene Expression Analysis Resource (gEAR; https://umgear.org/NIHL) and provides a blueprint for the rational development of drugs to prevent and treat NIHL.
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Affiliation(s)
- Beatrice Milon
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Eldad D Shulman
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Kathy S So
- Decibel Therapeutics, Boston, MA 02215, USA
| | - Christopher R Cederroth
- Laboratory of Experimental Audiology, Department of Physiology and Pharmacology, Karolinska Institute, 171 77 Stockholm, Sweden; Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham NG7 2UH, UK
| | - Erika L Lipford
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Michal Sperber
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | | - Heela Sarlus
- Laboratory of Experimental Audiology, Department of Physiology and Pharmacology, Karolinska Institute, 171 77 Stockholm, Sweden; Applied Immunology & Immunotherapy, Neuroimmunology Unit, Department of Clinical Neuroscience, Center for Molecular Medicine, Karolinska University Hospital, 171 77 Stockholm, Sweden
| | | | - Benjamin Shuster
- 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
| | - Sunayana Mitra
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Joshua Orvis
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Zachary Margulies
- 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
| | - Christopher Shults
- Department of Otorhinolaryngology Head and Neck Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | | | | | - Barbara Canlon
- Laboratory of Experimental Audiology, Department of Physiology and Pharmacology, Karolinska Institute, 171 77 Stockholm, Sweden
| | - Joe Burns
- Decibel Therapeutics, Boston, MA 02215, USA
| | - Ran Elkon
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, 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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7
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Hertzano R, Gwilliam K, Rose K, Milon B, Matern MS. Cell Type-Specific Expression Analysis of the Inner Ear: A Technical Report. Laryngoscope 2021; 131 Suppl 5:S1-S16. [PMID: 32579737 PMCID: PMC8996438 DOI: 10.1002/lary.28765] [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: 03/20/2020] [Revised: 04/21/2020] [Accepted: 05/01/2020] [Indexed: 01/11/2023]
Abstract
OBJECTIVE The cellular diversity of the inner ear has presented a technical challenge in obtaining molecular insight into its development and function. The application of technological advancements in cell type-specific expression enable clinicians and researchers to leap forward from classic genetics to obtaining mechanistic understanding of congenital and acquired hearing loss. This understanding is essential for development of therapeutics to prevent and reverse diseases of the inner ear, including hearing loss. The objective of this study is to describe and compare the available tools for cell type-specific analysis of the ear, as a means to support decision making in study design. STUDY DESIGN Three major approaches for cell type-specific analysis of the ear including fluorescence-activated cell sorting (FACS), ribosomal and RNA pulldown techniques, and single cell RNA-seq (scRNA-seq) are compared and contrasted using both published and original data. RESULTS We demonstrate the strength and weaknesses of these approaches leading to the inevitable conclusion that to maximize the utility of these approaches, it is important to match the experimental approach with the tissue of origin, cell type of interest, and the biological question. Often, a combined approach (eg, cell sorting and scRNA-seq or expression analysis using 2 separate approaches) is required. Finally, new tools for visualization and analysis of complex expression data, such as the gEAR platform (umgear.org), collate cell type-specific gene expression from the ear field and provide unprecedented access to both clinicians and researchers. LEVEL OF EVIDENCE N/A Laryngoscope, 131:S1-S16, 2021.
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Affiliation(s)
- Ronna Hertzano
- Department of Otorhinolaryngology Head and Neck Surgery University of Maryland School of Medicine 16 S Eutaw St. Suite 500 Baltimore Maryland 21201 U.S.A
- Institute for Genome Sciences, University of Maryland School of Medicine Baltimore Maryland U.S.A
- Department of Anatomy and Neurobiology University of Maryland School of Medicine Baltimore Maryland U.S.A
| | - Kathleen Gwilliam
- Department of Otorhinolaryngology Head and Neck Surgery University of Maryland School of Medicine 16 S Eutaw St. Suite 500 Baltimore Maryland 21201 U.S.A
| | - Kevin Rose
- Department of Otorhinolaryngology Head and Neck Surgery University of Maryland School of Medicine 16 S Eutaw St. Suite 500 Baltimore Maryland 21201 U.S.A
| | - Beatrice Milon
- Department of Otorhinolaryngology Head and Neck Surgery University of Maryland School of Medicine 16 S Eutaw St. Suite 500 Baltimore Maryland 21201 U.S.A
| | - Maggie S. Matern
- Department of Otorhinolaryngology Head and Neck Surgery University of Maryland School of Medicine 16 S Eutaw St. Suite 500 Baltimore Maryland 21201 U.S.A
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8
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Xu J, Yu D, Dong X, Xie X, Xu M, Guo L, Huang L, Tang Q, Gan L. GATA3 maintains the quiescent state of cochlear supporting cells by regulating p27 kip1. Sci Rep 2021; 11:15779. [PMID: 34349220 PMCID: PMC8338922 DOI: 10.1038/s41598-021-95427-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 07/26/2021] [Indexed: 01/22/2023] Open
Abstract
Haplo-insufficiency of the GATA3 gene causes hypoparathyroidism, sensorineural hearing loss, and renal disease (HDR) syndrome. Previous studies have shown that Gata3 is required for the development of the prosensory domain and spiral ganglion neurons (SGNs) of the mouse cochlea during embryogenesis. However, its role in supporting cells (SCs) after cell fate specification is largely unknown. In this study, we used tamoxifen-inducible Sox2CreERT2 mice to delete Gata3 in SCs of the neonatal mouse cochlea and showed that loss of Gata3 resulted in the proliferation of SCs, including the inner pillar cells (IPCs), inner border cells (IBCs), and lateral greater epithelium ridge (GER). In addition, loss of Gata3 resulted in the down-regulation of p27kip1, a cell cycle inhibitor, in the SCs of Gata3-CKO neonatal cochleae. Chromatin immunoprecipitation analysis revealed that GATA3 directly binds to p27kip1 promoter and could maintain the quiescent state of cochlear SCs by regulating p27kip1 expression. Furthermore, RNA-seq analysis revealed that loss of Gata3 function resulted in the change in the expression of genes essential for the development and function of cochlear SCs, including Tectb, Cyp26b1, Slitrk6, Ano1, and Aqp4.
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Affiliation(s)
- Jiadong Xu
- College of Life Sciences, Zhejiang University, Hangzhou, 310058, Zhejiang, China
- Department of Ophthalmology and Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA
| | - Dongliang Yu
- College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, Zhejiang, China
| | - Xuhui Dong
- Department of Ophthalmology and Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA
| | - Xiaoling Xie
- Department of Ophthalmology and Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA
| | - Mei Xu
- College of Life Sciences, Zhejiang University, Hangzhou, 310058, Zhejiang, China
- Department of Ophthalmology and Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA
| | - Luming Guo
- College of Life Sciences, Zhejiang University, Hangzhou, 310058, Zhejiang, China
- Department of Ophthalmology and Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA
| | - Liang Huang
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA
| | - Qi Tang
- Department of Ophthalmology and Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA
- Department of Otolaryngology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Lin Gan
- Department of Ophthalmology and Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA.
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA.
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Chen T, Rohacek AM, Caporizzo M, Nankali A, Smits JJ, Oostrik J, Lanting CP, Kücük E, Gilissen C, van de Kamp JM, Pennings RJE, Rakowiecki SM, Kaestner KH, Ohlemiller KK, Oghalai JS, Kremer H, Prosser BL, Epstein DJ. Cochlear supporting cells require GAS2 for cytoskeletal architecture and hearing. Dev Cell 2021; 56:1526-1540.e7. [PMID: 33964205 PMCID: PMC8137675 DOI: 10.1016/j.devcel.2021.04.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 02/01/2021] [Accepted: 04/16/2021] [Indexed: 11/16/2022]
Abstract
In mammals, sound is detected by mechanosensory hair cells that are activated in response to vibrations at frequency-dependent positions along the cochlear duct. We demonstrate that inner ear supporting cells provide a structural framework for transmitting sound energy through the cochlear partition. Humans and mice with mutations in GAS2, encoding a cytoskeletal regulatory protein, exhibit hearing loss due to disorganization and destabilization of microtubule bundles in pillar and Deiters' cells, two types of inner ear supporting cells with unique cytoskeletal specializations. Failure to maintain microtubule bundle integrity reduced supporting cell stiffness, which in turn altered cochlear micromechanics in Gas2 mutants. Vibratory responses to sound were measured in cochleae from live mice, revealing defects in the propagation and amplification of the traveling wave in Gas2 mutants. We propose that the microtubule bundling activity of GAS2 imparts supporting cells with mechanical properties for transmitting sound energy through the cochlea.
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Affiliation(s)
- Tingfang Chen
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Alex M Rohacek
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Matthew Caporizzo
- Department of Physiology, Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Amir Nankali
- The Caruso Department of Otolaryngology-Head and Neck Surgery, University of Southern California, Los Angeles, CA, USA
| | - Jeroen J Smits
- Department of Otorhinolaryngology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Jaap Oostrik
- Department of Otorhinolaryngology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Cornelis P Lanting
- Department of Otorhinolaryngology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Erdi Kücük
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Christian Gilissen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Jiddeke M van de Kamp
- Department of Clinical Genetics, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Ronald J E Pennings
- Department of Otorhinolaryngology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Staci M Rakowiecki
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Klaus H Kaestner
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kevin K Ohlemiller
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - John S Oghalai
- The Caruso Department of Otolaryngology-Head and Neck Surgery, University of Southern California, Los Angeles, CA, USA
| | - Hannie Kremer
- Department of Otorhinolaryngology, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Benjamin L Prosser
- Department of Physiology, Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Douglas J Epstein
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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10
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Ballesteros A, Fitzgerald TS, Swartz KJ. Expression of a membrane-targeted fluorescent reporter disrupts auditory hair cell mechanoelectrical transduction and causes profound deafness. Hear Res 2021; 404:108212. [PMID: 33667877 PMCID: PMC8035305 DOI: 10.1016/j.heares.2021.108212] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 02/11/2021] [Accepted: 02/13/2021] [Indexed: 11/22/2022]
Abstract
The reporter mT/mG mice expressing a membrane-targeted fluorescent protein are becoming widely used to study the auditory and vestibular system due to its versatility. Here we show that high expression levels of the fluorescent mtdTomato reporter affect the function of the sensory hair cells and the auditory performance of mT/mG transgenic mice. Auditory brainstem responses and distortion product otoacoustic emissions revealed that adult mT/mG homozygous mice are profoundly deaf, whereas heterozygous mice present high frequency loss. We explore whether this line would be useful for studying and visualizing the membrane of auditory hair cells by airyscan super-resolution confocal microscopy. Membrane localization of the reporter was observed in hair cells of the cochlea, facilitating imaging of both cell bodies and stereocilia bundles without altering cellular architecture or the expression of the integral membrane motor protein prestin. Remarkably, hair cells from mT/mG homozygous mice failed to uptake the FM1-43 dye and to locate TMC1 at the stereocilia, indicating defective mechanotransduction machinery. Our work emphasizes that precautions must be considered when working with reporter mice and highlights the potential role of the cellular membrane in maintaining functional hair cells and ensuring proper hearing.
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Affiliation(s)
- Angela Ballesteros
- Molecular Physiology and Biophysics Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, United States.
| | - Tracy S Fitzgerald
- Mouse Auditory Testing Core, National Institute on Deafness and other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, United States
| | - Kenton J Swartz
- Molecular Physiology and Biophysics Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, United States.
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11
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The Notch Ligand Jagged1 Is Required for the Formation, Maintenance, and Survival of Hensen's Cells in the Mouse Cochlea. J Neurosci 2020; 40:9401-9413. [PMID: 33127852 DOI: 10.1523/jneurosci.1192-20.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 10/16/2020] [Accepted: 10/23/2020] [Indexed: 01/09/2023] Open
Abstract
During cochlear development, the Notch ligand JAGGED 1 (JAG1) plays an important role in the specification of the prosensory region, which gives rise to sound-sensing hair cells and neighboring supporting cells (SCs). While JAG1's expression is maintained in SCs through adulthood, the function of JAG1 in SC development is unknown. Here, we demonstrate that JAG1 is essential for the formation and maintenance of Hensen's cells, a highly specialized SC subtype located at the edge of the auditory epithelium. Using Sox2 CreERT2/+::Jag1loxP/loxP mice of both genders, we show that Jag1 deletion at the onset of differentiation, at embryonic day 14.5, disrupted Hensen's cell formation. Similar loss of Hensen's cells was observed when Jag1 was deleted after Hensen's cell formation at postnatal day (P) 0/P1 and fate-mapping analysis revealed that in the absence of Jag1, some Hensen's cells die, but others convert into neighboring Claudius cells. In support of a role for JAG1 in cell survival, genes involved in mitochondrial function and protein synthesis were downregulated in the sensory epithelium of P0 cochlea lacking Jag1 Finally, using Fgfr3-iCreERT2 ::Jag1loxP/loxP mice to delete Jag1 at P0, we observed a similar loss of Hensen's cells and found that adult Jag1 mutant mice have hearing deficits at the low-frequency range.SIGNIFICANCE STATEMENT Hensen's cells play an essential role in the development and homeostasis of the cochlea. Defects in the biophysical or functional properties of Hensen's cells have been linked to auditory dysfunction and hearing loss. Despite their importance, surprisingly little is known about the molecular mechanisms that guide their development. Morphologic and fate-mapping analyses in our study revealed that, in the absence of the Notch ligand JAGGED1, Hensen's cells died or converted into Claudius cells, which are specialized epithelium-like cells outside the sensory epithelium. Confirming a link between JAGGED1 and cell survival, transcriptional profiling showed that JAGGED1 maintains genes critical for mitochondrial function and tissue homeostasis. Finally, auditory phenotyping revealed that JAGGED1's function in supporting cells is necessary for low-frequency hearing.
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Wu J, Dong X, Li W, Zhao L, Zhou L, Sun S, Li H. Dibenzazepine promotes cochlear supporting cell proliferation and hair cell regeneration in neonatal mice. Cell Prolif 2020; 53:e12872. [PMID: 32677724 PMCID: PMC7507434 DOI: 10.1111/cpr.12872] [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: 04/06/2020] [Revised: 06/04/2020] [Accepted: 06/17/2020] [Indexed: 12/13/2022] Open
Abstract
Objectives To investigate the role of dibenzazepine (DBZ) in promoting supporting cell (SC) proliferation and hair cell (HC) regeneration in the inner ear. Materials and Methods Postnatal day 1 wild‐type or neomycin‐damaged mouse cochleae were cultured with DBZ. Immunohistochemistry and scanning electron microscopy were used to examine the morphology of cochlear cells, and high‐throughput RNA‐sequencing was used to measure gene expression levels. Results We found that DBZ promoted SC proliferation and HC regeneration in a dose‐dependent manner in both normal and damaged cochleae. In addition, most of the newly regenerated HCs induced by DBZ had visible and relatively mature stereocilia bundle structures. Finally, RNA sequencing detected the differentially expressed genes between DBZ treatment and controls, and interaction networks were constructed for the most highly differentially expressed genes. Conclusions Our study demonstrates that DBZ can significantly promote SC proliferation and increase the number of mitotically regenerated HCs with relatively mature stereocilia bundles in the neonatal mouse cochlea by inhibiting Notch signalling and activating Wnt signalling, suggesting the DBZ might be a new therapeutic target for stimulating HC regeneration.
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Affiliation(s)
- Jingfang Wu
- Otorhinolaryngology Department of Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Biomedical Sciences, Fudan University School of Basic Medical Sciences, Shanghai, China
| | - Xinran Dong
- Molecular Medical Center, Children's Hospital of Fudan University, Shanghai, China
| | - Wen Li
- Otorhinolaryngology Department of Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Biomedical Sciences, Fudan University School of Basic Medical Sciences, Shanghai, China
| | - Liping Zhao
- Otorhinolaryngology Department of Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Biomedical Sciences, Fudan University School of Basic Medical Sciences, Shanghai, China
| | - Li Zhou
- Shanghai High School, Shanghai, China
| | - Shan Sun
- Otorhinolaryngology Department of Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Biomedical Sciences, Fudan University School of Basic Medical Sciences, Shanghai, China
| | - Huawei Li
- Otorhinolaryngology Department of Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Biomedical Sciences, Fudan University School of Basic Medical Sciences, Shanghai, China.,The Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China
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Liu LM, Zhao LP, Wu LJ, Guo L, Li WY, Chen Y. Characterization of the transcriptomes of Atoh1-induced hair cells in the mouse cochlea. AMERICAN JOURNAL OF STEM CELLS 2020; 9:1-15. [PMID: 32211215 PMCID: PMC7076321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Accepted: 02/11/2020] [Indexed: 06/10/2023]
Abstract
Postnatal mammalian cochlear hair cells (HCs) can be regenerated by direct transdifferentiation or by mitotic regeneration from supporting cells through many pathways, including Atoh1, Wnt, Hedgehog and Notch signaling. However, most new HCs are immature HCs. In this study we used RNA-Seq analysis to compare the differences between the transcriptomes of Atoh1 overexpression-induced new HCs and the native HCs, and to define the factors that might help to promote the maturation of new HCs. As expected, we found Atoh1-induced new HCs had obvious HC characteristics as demonstrated by the expression of HC markers such as Pou4f3 and Myosin VIIA (Myo7a). However, Atoh1-induced new HCs had significantly lower expression of genes that are related to HC function such as Slc26a5 (Prestin), Slc17a8 and Otof. We found that genes related to HC cell differentiation and maturation (Kcnma1, Myo6, Myo7a, Grxcr1, Gfi1, Wnt5a, Fgfr1, Gfi1, Fgf8 etc.) had significantly lower expression levels in new HCs compared to native HCs. In conclusion, we found a set of genes that might regulate the differentiation and maturation of new HCs, and these genes might serve as potential new therapeutic targets for functional HC regeneration and hearing recovery.
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Affiliation(s)
- Li-Man Liu
- ENT Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, Fudan UniversityShanghai 200031, China
| | - Li-Ping Zhao
- ENT Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, Fudan UniversityShanghai 200031, China
- NHC Key Laboratory of Hearing Medicine (Fudan University)Shanghai 200031, China
| | - Ling-Jie Wu
- ENT Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, Fudan UniversityShanghai 200031, China
- NHC Key Laboratory of Hearing Medicine (Fudan University)Shanghai 200031, China
| | - Luo Guo
- ENT Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, Fudan UniversityShanghai 200031, China
- NHC Key Laboratory of Hearing Medicine (Fudan University)Shanghai 200031, China
| | - Wen-Yan Li
- ENT Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, Fudan UniversityShanghai 200031, China
- NHC Key Laboratory of Hearing Medicine (Fudan University)Shanghai 200031, China
| | - Yan Chen
- ENT Institute and Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, Fudan UniversityShanghai 200031, China
- NHC Key Laboratory of Hearing Medicine (Fudan University)Shanghai 200031, China
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McGovern MM, Randle MR, Cuppini CL, Graves KA, Cox BC. Multiple supporting cell subtypes are capable of spontaneous hair cell regeneration in the neonatal mouse cochlea. Development 2019; 146:146/4/dev171009. [PMID: 30770379 DOI: 10.1242/dev.171009] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 01/09/2019] [Indexed: 12/20/2022]
Abstract
Supporting cells (SCs) are known to spontaneously regenerate hair cells (HCs) in the neonatal mouse cochlea, yet little is known about the relative contribution of distinct SC subtypes which differ in morphology and function. We have previously shown that HC regeneration is linked to Notch signaling, and some SC subtypes, but not others, lose expression of the Notch effector Hes5 Other work has demonstrated that Lgr5-positive SCs have an increased capacity to regenerate HCs; however, several SC subtypes express Lgr5. To further investigate the source for spontaneous HC regeneration, we used three CreER lines to fate-map distinct groups of SCs during regeneration. Fate-mapping either alone or combined with a mitotic tracer showed that pillar and Deiters' cells contributed more regenerated HCs overall. However, when normalized to the total fate-mapped population, pillar, Deiters', inner phalangeal and border cells had equal capacity to regenerate HCs, and all SC subtypes could divide after HC damage. Investigating the mechanisms that allow individual SC subtypes to regenerate HCs and the postnatal changes that occur in each group during maturation could lead to therapies for hearing loss.
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Affiliation(s)
- Melissa M McGovern
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL 62711, USA
| | - Michelle R Randle
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL 62711, USA
| | - Candice L Cuppini
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL 62711, USA
| | - Kaley A Graves
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL 62711, USA
| | - Brandon C Cox
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL 62711, USA .,Department of Surgery, Division of Otolaryngology, Southern Illinois University School of Medicine, Springfield, IL 62711, USA
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15
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Abstract
Neurons of the cochleovestibular ganglion (CVG) transmit hearing and balance information to the brain. During development, a select population of early otic progenitors express NEUROG1, delaminate from the otocyst, and coalesce to form the neurons that innervate all inner ear sensory regions. At present, the selection process that determines which otic progenitors activate NEUROG1 and adopt a neuroblast fate is incompletely understood. The transcription factor SOX2 has been implicated in otic neurogenesis, but its requirement in the specification of the CVG neurons has not been established. Here we tested SOX2's requirement during inner ear neuronal specification using a conditional deletion paradigm in the mouse. SOX2 deficiency at otocyst stages caused a near-absence of NEUROG1-expressing neuroblasts, increased cell death in the neurosensory epithelium, and significantly reduced the CVG volume. Interestingly, a milder decrease in neurogenesis was observed in heterozygotes, indicating SOX2 levels are important. Moreover, fate-mapping experiments revealed that the timing of SOX2 expression did not parallel the established vestibular-then-auditory sequence. These results demonstrate that SOX2 is required for the initial events in otic neuronal specification including expression of NEUROG1, although fate-mapping results suggest SOX2 may be required as a competence factor rather than a direct initiator of the neural fate.
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Affiliation(s)
- Aleta R Steevens
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY, USA
| | | | - Jenna C Glatzer
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY, USA
| | - Amy E Kiernan
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY, USA. .,Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, NY, USA.
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Gfi1 Cre mice have early onset progressive hearing loss and induce recombination in numerous inner ear non-hair cells. Sci Rep 2017; 7:42079. [PMID: 28181545 PMCID: PMC5299610 DOI: 10.1038/srep42079] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 01/05/2017] [Indexed: 12/20/2022] Open
Abstract
Studies of developmental and functional biology largely rely on conditional expression of genes in a cell type-specific manner. Therefore, the importance of specificity and lack of inherent phenotypes for Cre-driver animals cannot be overemphasized. The Gfi1Cre mouse is commonly used for conditional hair cell-specific gene deletion/reporter gene activation in the inner ear. Here, using immunofluorescence and flow cytometry, we show that the Gfi1Cre mice produce a pattern of recombination that is not strictly limited to hair cells within the inner ear. We observe a broad expression of Cre recombinase in the Gfi1Cre mouse neonatal inner ear, primarily in inner ear resident macrophages, which outnumber the hair cells. We further show that heterozygous Gfi1Cre mice exhibit an early onset progressive hearing loss as compared with their wild-type littermates. Importantly, vestibular function remains intact in heterozygotes up to 10 months, the latest time point tested. Finally, we detect minor, but statistically significant, changes in expression of hair cell-enriched transcripts in the Gfi1Cre heterozygous mice cochleae compared with their wild-type littermate controls. Given the broad use of the Gfi1Cre mice, both for gene deletion and reporter gene activation, these data are significant and necessary for proper planning and interpretation of experiments.
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17
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Zheng F, Zuo J. Cochlear hair cell regeneration after noise-induced hearing loss: Does regeneration follow development? Hear Res 2016; 349:182-196. [PMID: 28034617 DOI: 10.1016/j.heares.2016.12.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 11/22/2016] [Accepted: 12/20/2016] [Indexed: 12/14/2022]
Abstract
Noise-induced hearing loss (NIHL) affects a large number of military personnel and civilians. Regenerating inner-ear cochlear hair cells (HCs) is a promising strategy to restore hearing after NIHL. In this review, we first summarize recent transcriptome profile analysis of zebrafish lateral lines and chick utricles where spontaneous HC regeneration occurs after HC damage. We then discuss recent studies in other mammalian regenerative systems such as pancreas, heart and central nervous system. Both spontaneous and forced HC regeneration occurs in mammalian cochleae in vivo involving proliferation and direct lineage conversion. However, both processes are inefficient and incomplete, and decline with age. For direct lineage conversion in vivo in cochleae and in other systems, further improvement requires multiple factors, including transcription, epigenetic and trophic factors, with appropriate stoichiometry in appropriate architectural niche. Increasing evidence from other systems indicates that the molecular paths of direct lineage conversion may be different from those of normal developmental lineages. We therefore hypothesize that HC regeneration does not have to follow HC development and that epigenetic memory of supporting cells influences the HC regeneration, which may be a key to successful cochlear HC regeneration. Finally, we discuss recent efforts in viral gene therapy and drug discovery for HC regeneration. We hope that combination therapy targeting multiple factors and epigenetic signaling pathways will provide promising avenues for HC regeneration in humans with NIHL and other types of hearing loss.
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Affiliation(s)
- Fei Zheng
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, MS 322, Memphis, TN 38105, United States.
| | - Jian Zuo
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, MS 322, Memphis, TN 38105, United States.
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McGovern MM, Brancheck J, Grant AC, Graves KA, Cox BC. Quantitative Analysis of Supporting Cell Subtype Labeling Among CreER Lines in the Neonatal Mouse Cochlea. J Assoc Res Otolaryngol 2016; 18:227-245. [PMID: 27873085 DOI: 10.1007/s10162-016-0598-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 10/17/2016] [Indexed: 11/30/2022] Open
Abstract
Four CreER lines that are commonly used in the auditory field to label cochlear supporting cells (SCs) are expressed in multiple SC subtypes, with some lines also showing reporter expression in hair cells (HCs). We hypothesized that altering the tamoxifen dose would modify CreER expression and target subsets of SCs. We also used two different reporter lines, ROSA26 tdTomato and CAG-eGFP, to achieve the same goal. Our results confirm previous reports that Sox2 CreERT2 and Fgfr3-iCreER T2 are not only expressed in neonatal SCs but also in HCs. Decreasing the tamoxifen dose did not reduce HC expression for Sox2 CreERT2 , but changing to the CAG-eGFP reporter decreased reporter-positive HCs sevenfold. However, there was also a significant decrease in the number of reporter-positive SCs. In contrast, there was a large reduction in reporter-positive HCs in Fgfr3-iCreER T2 mice with the lowest tamoxifen dose tested yet only limited reduction in SC labeling. The targeting of reporter expression to inner phalangeal and border cells was increased when Plp-CreER T2 was paired with the CAG-eGFP reporter; however, the total number of labeled cells decreased. Changes to the tamoxifen dose or reporter line with Prox1 CreERT2 caused minimal changes. Our data demonstrate that modifications to the tamoxifen dose or the use of different reporter lines may be successful in narrowing the numbers and/or types of cells labeled, but each CreER line responded differently. When the ROSA26 tdTomato reporter was combined with any of the four CreER lines, there was no difference in the number of tdTomato-positive cells after one or two injections of tamoxifen given at birth. Thus, tamoxifen-mediated toxicity could be reduced by only giving one injection. While the CAG-eGFP reporter consistently labeled fewer cells, both reporter lines are valuable depending on the goal of the study.
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Affiliation(s)
- Melissa M McGovern
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, 62711, USA
| | - Joseph Brancheck
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, 62711, USA
| | - Auston C Grant
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, 62711, USA
| | - Kaley A Graves
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, 62711, USA
| | - Brandon C Cox
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, 62711, USA.
- Department of Surgery, Division of Otolaryngology, Southern Illinois University School of Medicine, Springfield, IL, 62711, USA.
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Puligilla C, Kelley MW. Dual role for Sox2 in specification of sensory competence and regulation of Atoh1 function. Dev Neurobiol 2016; 77:3-13. [PMID: 27203669 DOI: 10.1002/dneu.22401] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 03/11/2016] [Accepted: 03/14/2016] [Indexed: 11/08/2022]
Abstract
The formation of inner ear sensory epithelia is believed to occur in two steps, initial specification of sensory competent (prosensory) regions followed by determination of specific cell-types, such as hair cells (HCs) and supporting cells. However, studies in which the HC determination factor Atoh1 was ectopically expressed in nonprosensory regions indicated that expression of Atoh1 alone is sufficient to induce HC formation suggesting that prosensory formation may not be a prerequisite for HC development. To test this hypothesis, interactions between Sox2 and Atoh1, which are required for prosensory and HC formation respectively, were examined. Forced expression of Atoh1 in nonprosensory cells resulted in transient expression of Sox2 prior to HC formation, suggesting that expression of Sox2 is required for formation of ectopic HCs. Moreover, Atoh1 overexpression failed to induce HC formation in Sox2 mutants, confirming that Sox2 is required for prosensory competence. To determine whether expression of Sox2 alone is sufficient to induce prosensory identity, Sox2 was transiently activated in a manner that mimicked endogenous expression. Following transient Sox2 activation, nonprosensory cells developed as HCs, a result that was never observed in response to persistent expression of Sox2. These results, suggest a dual role for Sox2 in inner ear formation. Initially, Sox2 is required to specify prosensory competence, but subsequent down-regulation of Sox2 must occur to allow Atoh1 expression, most likely through a direct interaction with the Atoh1 promoter. These results implicate Sox2-mediated changes in prosensory cells as an essential step in their ability to develop as HCs. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 3-13, 2017.
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Affiliation(s)
- Chandrakala Puligilla
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, 29425
| | - Matthew W Kelley
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, 20982
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Riccardi S, Bergling S, Sigoillot F, Beibel M, Werner A, Leighton-Davies J, Knehr J, Bouwmeester T, Parker CN, Roma G, Kinzel B. MiR-210 promotes sensory hair cell formation in the organ of corti. BMC Genomics 2016; 17:309. [PMID: 27121005 PMCID: PMC4848794 DOI: 10.1186/s12864-016-2620-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Accepted: 04/14/2016] [Indexed: 12/20/2022] Open
Abstract
Background Hearing loss is the most common sensory defect afflicting several hundred million people worldwide. In most cases, regardless of the original cause, hearing loss is related to the degeneration and death of hair cells and their associated spiral ganglion neurons. Despite this knowledge, relatively few studies have reported regeneration of the auditory system. Significant gaps remain in our understanding of the molecular mechanisms underpinning auditory function, including the factors required for sensory cell regeneration. Recently, the identification of transcriptional activators and repressors of hair cell fate has been augmented by the discovery of microRNAs (miRNAs) associated with hearing loss. As miRNAs are central players of differentiation and cell fate, identification of miRNAs and their gene targets may reveal new pathways for hair cell regeneration, thereby providing new avenues for the treatment of hearing loss. Results In order to identify new genetic elements enabling regeneration of inner ear sensory hair cells, next-generation miRNA sequencing (miRSeq) was used to identify the most prominent miRNAs expressed in the mouse embryonic inner ear cell line UB/OC-1 during differentiation towards a hair cell like phenotype. Based on these miRSeq results eight most differentially expressed miRNAs were selected for further characterization. In UB/OC-1, miR-210 silencing in vitro resulted in hair cell marker expression, whereas ectopic expression of miR-210 resulted in new hair cell formation in cochlear explants. Using a lineage tracing mouse model, transdifferentiation of supporting epithelial cells was identified as the likely mechanism for this new hair cell formation. Potential miR-210 targets were predicted in silico and validated experimentally using a miR-trap approach. Conclusion MiRSeq followed by ex vivo validation revealed miR-210 as a novel factor driving transdifferentiation of supporting epithelial cells to sensory hair cells suggesting that miR-210 might be a potential new factor for hearing loss therapy. In addition, identification of inner ear pathways regulated by miR-210 identified potential new drug targets for the treatment of hearing loss. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2620-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sabrina Riccardi
- Developmental and Molecular Pathways, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Sebastian Bergling
- Developmental and Molecular Pathways, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Frederic Sigoillot
- Developmental and Molecular Pathways, Novartis Institute for Biomedical Research, Cambridge, USA
| | - Martin Beibel
- Developmental and Molecular Pathways, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Annick Werner
- Developmental and Molecular Pathways, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Juliet Leighton-Davies
- Developmental and Molecular Pathways, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Judith Knehr
- Developmental and Molecular Pathways, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Tewis Bouwmeester
- Developmental and Molecular Pathways, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Christian N Parker
- Developmental and Molecular Pathways, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Guglielmo Roma
- Developmental and Molecular Pathways, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Bernd Kinzel
- Developmental and Molecular Pathways, Novartis Institute for Biomedical Research, Basel, Switzerland.
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