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He W, Wu F, Xiong H, Zeng J, Gao Y, Cai Z, Pang J, Zheng Y. Promoting TFEB nuclear localization with curcumin analog C1 attenuates sensory hair cell injury and delays age-related hearing loss in C57BL/6 mice. Neurotoxicology 2023; 95:218-231. [PMID: 36792013 DOI: 10.1016/j.neuro.2023.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/16/2023] [Accepted: 02/13/2023] [Indexed: 02/16/2023]
Abstract
Sensory hair cell (HC) injuries, especially outer hair cell (OHC) loss, are well-documented to be the primary pathology of age-related hearing loss (AHL). Recent studies have demonstrated that autophagy plays an important role in HC injury in the inner ear. In our previous works, a decline in autophagy levels and HC loss were found to occur simultaneously in the inner ears of aged C57BL/6 mice, and the administration of rapamycin promoted autophagy levels, which reduced OHC loss and delayed AHL, but the underlying mechanism of autophagy in AHL has not been well elucidated. Transcription factor EB (TFEB), an autophagy regulator and the downstream target of mammalian target of rapamycin (mTOR), is involved in the pathological development of neurodegenerative disease. This study would address the link between autophagy and TFEB in aged C57BL/6 mouse cochleae and clarify the effect of the TFEB activator curcumin analog C1 (C1) in aged cochleae. Decreased TFEB nuclear localization (p = 0.0371) and autophagy dysfunction (p = 0.0273) were observed in the cochleae of aged C57BL/6 mice that exhibited AHL, HCs loss and HCs senescence. Treatment with C1 promoted TFEB nuclear localization and restored autophagy, subsequently alleviating HC injury and delaying AHL. The protective effect of C1 on HEI-OC1 cells against autophagy disorder and aging induced by D-galactose was abolished by chloroquine, which is one of the commonly used autophagy inhibitors. Overall, our results demonstrated that the capacity to perform autophagy is mediated by the nuclear localization of TFEB in aged C57BL/6 mouse cochleae. C1 promotes the nuclear localization of TFEB, subsequently alleviating HC injury and delaying AHL by restoring the impaired autophagy function. TFEB may serve as a new therapeutic target for AHL treatment.
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Affiliation(s)
- Wuhui He
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Fan Wu
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Hao Xiong
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China
| | - Junbo Zeng
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China
| | - Yiming Gao
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Ziyi Cai
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Jiaqi Pang
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
| | - Yiqing Zheng
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China.
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O'Sullivan JDB, Bullen A, Mann ZF. Mitochondrial form and function in hair cells. Hear Res 2023; 428:108660. [PMID: 36525891 DOI: 10.1016/j.heares.2022.108660] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 11/07/2022] [Accepted: 11/23/2022] [Indexed: 11/27/2022]
Abstract
Hair cells (HCs) are specialised sensory receptors residing in the neurosensory epithelia of inner ear sense organs. The precise morphological and physiological properties of HCs allow us to perceive sound and interact with the world around us. Mitochondria play a significant role in normal HC function and are also intricately involved in HC death. They generate ATP essential for sustaining the activity of ion pumps, Ca2+ transporters and the integrity of the stereociliary bundle during transduction as well as regulating cytosolic calcium homoeostasis during synaptic transmission. Advances in imaging techniques have allowed us to study mitochondrial populations throughout the HC, and how they interact with other organelles. These analyses have identified distinct mitochondrial populations between the apical and basolateral portions of the HC, in which mitochondrial morphology appears determined by the physiological processes in the different cellular compartments. Studies in HCs across species show that ototoxic agents, ageing and noise damage directly impact mitochondrial structure and function resulting in HC death. Deciphering the molecular mechanisms underlying this mitochondrial sensitivity, and how their morphology relates to their function during HC death, requires that we first understand this relationship in the context of normal HC function.
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Affiliation(s)
- James D B O'Sullivan
- Centre for Craniofacial and Regenerative Biology, Faculty of Dentistry, Oral, Craniofacial Sciences, King's College London, London SE1 9RT, U.K
| | - Anwen Bullen
- UCL Ear Institute, University College London, London WC1×8EE, U.K.
| | - Zoë F Mann
- Centre for Craniofacial and Regenerative Biology, Faculty of Dentistry, Oral, Craniofacial Sciences, King's College London, London SE1 9RT, U.K.
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3
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White PM. Perspectives on Human Hearing Loss, Cochlear Regeneration, and the Potential for Hearing Restoration Therapies. Brain Sci 2020; 10:brainsci10100756. [PMID: 33092183 PMCID: PMC7589617 DOI: 10.3390/brainsci10100756] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/13/2020] [Accepted: 10/16/2020] [Indexed: 12/23/2022] Open
Abstract
Most adults who acquire hearing loss find it to be a disability that is poorly corrected by current prosthetics. This gap drives current research in cochlear mechanosensory hair cell regeneration and in hearing restoration. Birds and fish can spontaneously regenerate lost hair cells through a process that has become better defined in the last few years. Findings from these studies have informed new research on hair cell regeneration in the mammalian cochlea. Hair cell regeneration is one part of the greater problem of hearing restoration, as hearing loss can stem from a myriad of causes. This review discusses these issues and recent findings, and places them in the greater social context of need and community.
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Affiliation(s)
- Patricia M White
- Department of Neuroscience, Ernest J. Del Monte Institute for Neuroscience, University of Rochester Medical Center, 601 Elmwood Ave, Rochester, NY 14642, USA
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4
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Forge A, Jagger DJ, Gale JE. Restoring the balance: regeneration of hair cells in the vestibular system of the inner ear. CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2019.12.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Smith KE, Whitcroft K, Law S, Andrews P, Choi D, Jagger DJ. Olfactory ensheathing cells from the nasal mucosa and olfactory bulb have distinct membrane properties. J Neurosci Res 2019; 98:888-901. [PMID: 31797433 DOI: 10.1002/jnr.24566] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 11/14/2019] [Accepted: 11/14/2019] [Indexed: 12/15/2022]
Abstract
Transplantation of olfactory ensheathing cells (OECs) is a potential therapy for the regeneration of damaged neurons. While they maintain tissue homeostasis in the olfactory mucosa (OM) and olfactory bulb (OB), their regenerative properties also support the normal sense of smell by enabling continual turnover and axonal regrowth of olfactory sensory neurons (OSNs). However, the molecular physiology of OECs is not fully understood, especially that of OECs from the mucosa. Here, we carried out whole-cell patch-clamp recordings from individual OECs cultured from the OM and OB of the adult rat, and from the human OM. A subset of OECs from the rat OM cultured 1-3 days in vitro had large weakly rectifying K+ currents, which were sensitive to Ba2+ and desipramine, blockers of Kir4-family channels. Kir4.1 immunofluorescence was detectable in cultured OM cells colabeled for the OEC marker S100, and in S100-labeled cells found adjacent to OSN axons in mucosal sections. OECs cultured from rat OB had distinct properties though, displaying strongly rectifying inward currents at hyperpolarized membrane potentials and strongly rectifying outward currents at depolarized potentials. Kir4.1 immunofluorescence was not evident in OECs adjacent to axons of OSNs in the OB. A subset of human OECs cultured from the OM of adults had membrane properties comparable to those of the rat OM that is dominated by Ba2+ -sensitive weak inwardly rectifying currents. The membrane properties of peripheral OECs are different to those of central OECs, suggesting they may play distinct roles during olfaction.
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Affiliation(s)
- Katie E Smith
- UCL Ear Institute, University College London, London, UK
| | - Katherine Whitcroft
- UCL Ear Institute, University College London, London, UK.,Royal National Throat Nose & Ear Hospital, London, UK
| | - Stuart Law
- Institute of Neurology, University College London, London, UK
| | - Peter Andrews
- UCL Ear Institute, University College London, London, UK.,Royal National Throat Nose & Ear Hospital, London, UK
| | - David Choi
- Institute of Neurology, University College London, London, UK
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6
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Pang J, Xiong H, Ou Y, Yang H, Xu Y, Chen S, Lai L, Ye Y, Su Z, Lin H, Huang Q, Xu X, Zheng Y. SIRT1 protects cochlear hair cell and delays age-related hearing loss via autophagy. Neurobiol Aging 2019; 80:127-137. [PMID: 31170533 DOI: 10.1016/j.neurobiolaging.2019.04.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 03/29/2019] [Accepted: 04/04/2019] [Indexed: 12/16/2022]
Abstract
Age-related hearing loss (AHL) is typically caused by the irreversible death of hair cells (HCs). Autophagy is a constitutive pathway to strengthen cell survival under normal or stress condition. Our previous work suggested that impaired autophagy played an important role in the development of AHL in C57BL/6 mice, although the underlying mechanism of autophagy in AHL still needs to be investigated. SIRT1 as an important regulator involves in AHL and is also a regulator of autophagy. Thus, we hypothesized that the modulation between SIRT1 and autophagy contribute to HC death and the progressive hearing dysfunction in aging. In the auditory cell line HEI-OC1, SIRT1 modulated autophagosome induction because of SIRT1 deacetylating a core autophagy protein ATG9A. The deacetylation of ATG9A not only affects the autophagosome membrane formation but also acts as a sensor of endoplasmic reticulum (ER) stress inducing autophagy. Moreover, the silencing of SIRT1 facilitated cell death via autophagy inhibition, whereas SIRT1 and autophagy activation reversed the SIRT1 inhibition media cell death. Notably, resveratrol, the first natural agonist of SIRT1, altered the organ of Corti autophagy impairment of the 12-month-old C57BL/6 mice and delayed AHL. The activation of SIRT1 modulates the deacetylation status of ATG9A, which acts as a sensor of ER stress, providing a novel perspective in elucidating the link between ER stress and autophagy in aging. Because SIRT1 activation restores autophagy with reduced HC death and hearing loss, it could be used as a strategy to delay AHL.
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Affiliation(s)
- Jiaqi Pang
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China; RNA Biomedical Institute, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Hao Xiong
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Department of Hearing and Speech Science, Xinhua College, Sun Yat-sen University, Guangzhou, China
| | - Yongkang Ou
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Department of Hearing and Speech Science, Xinhua College, Sun Yat-sen University, Guangzhou, China
| | - Haidi Yang
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Department of Hearing and Speech Science, Xinhua College, Sun Yat-sen University, Guangzhou, China
| | - Yaodong Xu
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China
| | - Suijun Chen
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Department of Hearing and Speech Science, Xinhua College, Sun Yat-sen University, Guangzhou, China
| | - Lan Lai
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Yongyi Ye
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; School of Public Health, Sun Yat-Sen University, Guangzhou, China
| | - Zhongwu Su
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China
| | - Hanqing Lin
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China
| | - Qiuhong Huang
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Department of Hearing and Speech Science, Xinhua College, Sun Yat-sen University, Guangzhou, China
| | - Xiaoding Xu
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China; RNA Biomedical Institute, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China.
| | - Yiqing Zheng
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Department of Hearing and Speech Science, Xinhua College, Sun Yat-sen University, Guangzhou, China.
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7
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Werner M, Van De Water TR, Stenlund H, Berggren D. Ultrastructural Characterization of Stem Cell-Derived Replacement Vestibular Hair Cells Within Ototoxin-Damaged Rat Utricle Explants. Anat Rec (Hoboken) 2019; 303:506-515. [PMID: 31090209 PMCID: PMC7065082 DOI: 10.1002/ar.24148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 08/23/2018] [Accepted: 09/07/2018] [Indexed: 11/25/2022]
Abstract
The auditory apparatus of the inner ear does not show turnover of sensory hair cells (HCs) in adult mammals; in contrast, there are many observations supporting low‐level turnover of vestibular HCs within the balance organs of mammalian inner ears. This low‐level renewal of vestibular HCs exists during normal conditions and it is further enhanced after trauma‐induced loss of these HCs. The main process for renewal of HCs within mammalian vestibular epithelia is a conversion/transdifferentiation of existing supporting cells (SCs) into replacement HCs.In earlier studies using long‐term organ cultures of postnatal rat macula utriculi, HC loss induced by gentamicin resulted in an initial substantial decline in HC density followed by a significant increase in the proportion of HCs to SCs indicating the production of replacement HCs. In the present study, using the same model of ototoxic damage to study renewal of vestibular HCs, we focus on the ultrastructural characteristics of SCs undergoing transdifferentiation into new HCs. Our objective was to search for morphological signs of SC plasticity during this process. In the utricular epithelia, we observed immature HCs, which appear to be SCs transdifferentiating into HCs. These bridge SCs have unique morphological features characterized by formation of foot processes, basal accumulation of mitochondria, and an increased amount of connections with nearby SCs. No gap junctions were observed on these transitional cells. The tight junction seals were morphologically intact in both control and gentamicin‐exposed explants. Anat Rec, 303:506–515, 2020. © 2019 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.
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Affiliation(s)
- Mimmi Werner
- Department of Clinical Sciences, Otolaryngology, University of Umeå, Umeå, Sweden
| | - Thomas R Van De Water
- Cochlear Implant Research Program, Department of Otolaryngology, University of Miami Ear Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - Hans Stenlund
- Department of Epidemiology and Global Health, University of Umeå, Umeå, Sweden
| | - Diana Berggren
- Department of Clinical Sciences, Otolaryngology, University of Umeå, Umeå, Sweden
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8
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Chang-Chien J, Yen YC, Li SY, Hsu TC, Yang JJ. Ferulic acid-mediated protection against neomycin-induced hair cell loss in transgenic zebrafish. J Funct Foods 2017. [DOI: 10.1016/j.jff.2016.11.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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9
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Han C, Linser P, Park HJ, Kim MJ, White K, Vann JM, Ding D, Prolla TA, Someya S. Sirt1 deficiency protects cochlear cells and delays the early onset of age-related hearing loss in C57BL/6 mice. Neurobiol Aging 2016; 43:58-71. [PMID: 27255815 DOI: 10.1016/j.neurobiolaging.2016.03.023] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 02/29/2016] [Accepted: 03/22/2016] [Indexed: 10/22/2022]
Abstract
Hearing gradually declines with age in both animals and humans, and this condition is known as age-related hearing loss (AHL). Here, we investigated the effects of deficiency of Sirt1, a member of the mammalian sirtuin family, on age-related cochlear pathology and associated hearing loss in C57BL/6 mice, a mouse model of early-onset AHL. Sirt1 deficiency reduced age-related oxidative damage of cochlear hair cells and spiral ganglion neurons and delayed the early onset of AHL. In cultured mouse inner ear cell lines, Sirt1 knockdown increased cell viability under oxidative stress conditions, induced nuclear translocation of Foxo3a, and increased acetylation status of Foxo3a. This resulted in increased activity of the antioxidant enzyme catalase. In young wild-type mice, both Sirt1 and Foxo3a proteins resided in the cytoplasm of the supporting cells within the organ of Corti of the cochlea. Therefore, our findings suggest that SIRT1 promotes early-onset AHL through suppressing FOXO3a-mediated oxidative stress resistance in the cochlea of C57BL/6 mice.
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Affiliation(s)
- Chul Han
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA
| | - Paul Linser
- Whitney Laboratory, University of Florida, St Augustine, FL, USA
| | - Hyo-Jin Park
- Department of Neurology, University of Florida, Gainesville, FL, USA
| | - Mi-Jung Kim
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA
| | - Karessa White
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA
| | - James M Vann
- Department of Genetics, University of Wisconsin, Madison, WI, USA; Department of Medical Genetics, University of Wisconsin, Madison, WI, USA
| | - Dalian Ding
- Center for Hearing and Deafness, State University of New York at Buffalo, NY, USA
| | - Tomas A Prolla
- Department of Genetics, University of Wisconsin, Madison, WI, USA; Department of Medical Genetics, University of Wisconsin, Madison, WI, USA
| | - Shinichi Someya
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA.
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10
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Taylor RR, Jagger DJ, Saeed SR, Axon P, Donnelly N, Tysome J, Moffatt D, Irving R, Monksfield P, Coulson C, Freeman SR, Lloyd SK, Forge A. Characterizing human vestibular sensory epithelia for experimental studies: new hair bundles on old tissue and implications for therapeutic interventions in ageing. Neurobiol Aging 2015; 36:2068-84. [PMID: 25818177 PMCID: PMC4436436 DOI: 10.1016/j.neurobiolaging.2015.02.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 02/09/2015] [Accepted: 02/11/2015] [Indexed: 12/19/2022]
Abstract
Balance disequilibrium is a significant contributor to falls in the elderly. The most common cause of balance dysfunction is loss of sensory cells from the vestibular sensory epithelia of the inner ear. However, inaccessibility of inner ear tissue in humans severely restricts possibilities for experimental manipulation to develop therapies to ameliorate this loss. We provide a structural and functional analysis of human vestibular sensory epithelia harvested at trans-labyrinthine surgery. We demonstrate the viability of the tissue and labeling with specific markers of hair cell function and of ion homeostasis in the epithelium. Samples obtained from the oldest patients revealed a significant loss of hair cells across the tissue surface, but we found immature hair bundles present in epithelia harvested from patients >60 years of age. These results suggest that the environment of the human vestibular sensory epithelium could be responsive to stimulation of developmental pathways to enhance hair cell regeneration, as has been demonstrated successfully in the vestibular organs of adult mice.
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Affiliation(s)
| | | | - Shakeel R Saeed
- UCL Ear Institute, London, UK; Royal National Throat Nose and Ear Hospital, UCLH NHS Foundation Trust, London, UK
| | - Patrick Axon
- Addenbrooke's Hospital, Cambridge University NHS Foundation Trust, Cambridge, UK
| | - Neil Donnelly
- Addenbrooke's Hospital, Cambridge University NHS Foundation Trust, Cambridge, UK
| | - James Tysome
- Addenbrooke's Hospital, Cambridge University NHS Foundation Trust, Cambridge, UK
| | - David Moffatt
- Addenbrooke's Hospital, Cambridge University NHS Foundation Trust, Cambridge, UK
| | - Richard Irving
- Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Medical Centre, Birmingham, UK
| | - Peter Monksfield
- Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Medical Centre, Birmingham, UK
| | - Chris Coulson
- Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Medical Centre, Birmingham, UK
| | - Simon R Freeman
- Manchester Royal Infirmary, Central Manchester University Hospitals NHS Trust, Manchester, UK; Salford Royal Infirmary, Salford Royal NHS Foundation Trust, Salford, UK
| | - Simon K Lloyd
- Manchester Royal Infirmary, Central Manchester University Hospitals NHS Trust, Manchester, UK; Salford Royal Infirmary, Salford Royal NHS Foundation Trust, Salford, UK
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11
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Wingard JC, Zhao HB. Cellular and Deafness Mechanisms Underlying Connexin Mutation-Induced Hearing Loss - A Common Hereditary Deafness. Front Cell Neurosci 2015; 9:202. [PMID: 26074771 PMCID: PMC4448512 DOI: 10.3389/fncel.2015.00202] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Accepted: 05/11/2015] [Indexed: 11/30/2022] Open
Abstract
Hearing loss due to mutations in the connexin gene family, which encodes gap junctional proteins, is a common form of hereditary deafness. In particular, connexin 26 (Cx26, GJB2) mutations are responsible for ~50% of non-syndromic hearing loss, which is the highest incidence of genetic disease. In the clinic, Cx26 mutations cause various auditory phenotypes ranging from profound congenital deafness at birth to mild, progressive hearing loss in late childhood. Recent experiments demonstrate that congenital deafness mainly results from cochlear developmental disorders rather than hair cell degeneration and endocochlear potential reduction, while late-onset hearing loss results from reduction of active cochlear amplification, even though cochlear hair cells have no connexin expression. However, there is no apparent, demonstrable relationship between specific changes in connexin (channel) functions and the phenotypes of mutation-induced hearing loss. Moreover, new experiments further demonstrate that the hypothesized K+-recycling disruption is not a principal deafness mechanism for connexin deficiency induced hearing loss. Cx30 (GJB6), Cx29 (GJC3), Cx31 (GJB3), and Cx43 (GJA1) mutations can also cause hearing loss with distinct pathological changes in the cochlea. These new studies provide invaluable information about deafness mechanisms underlying connexin mutation-induced hearing loss and also provide important information for developing new protective and therapeutic strategies for this common deafness. However, the detailed cellular mechanisms underlying these pathological changes remain unclear. Also, little is known about specific mutation-induced pathological changes in vivo and little information is available for humans. Such further studies are urgently required.
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Affiliation(s)
- Jeffrey C Wingard
- Department of Otolaryngology, University of Kentucky Medical Center , Lexington, KY , USA
| | - Hong-Bo Zhao
- Department of Otolaryngology, University of Kentucky Medical Center , Lexington, KY , USA
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12
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XIRP2, an actin-binding protein essential for inner ear hair-cell stereocilia. Cell Rep 2015; 10:1811-8. [PMID: 25772365 DOI: 10.1016/j.celrep.2015.02.042] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 01/30/2015] [Accepted: 02/14/2015] [Indexed: 01/20/2023] Open
Abstract
Hair cells of the inner ear are mechanoreceptors for hearing and balance, and proteins highly enriched in hair cells may have specific roles in the development and maintenance of the mechanotransduction apparatus. We identified XIRP2/mXinβ as an enriched protein likely to be essential for hair cells. We found that different isoforms of this protein are expressed and differentially located: short splice forms (also called XEPLIN) are targeted more to stereocilia, whereas two long isoforms containing a XIN-repeat domain are in both stereocilia and cuticular plates. Mice lacking the Xirp2 gene developed normal stereocilia bundles, but these degenerated with time: stereocilia were lost and long membranous protrusions emanated from the nearby apical surfaces. At an ultrastructural level, the paracrystalline actin filaments became disorganized. XIRP2 is apparently involved in the maintenance of actin structures in stereocilia and cuticular plates of hair cells, and perhaps in other organs where it is expressed.
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