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Pasdelou MP, Byelyayeva L, Malmström S, Pucheu S, Peytavy M, Laullier H, Hodges DB, Tzafriri AR, Naert G. Ototoxicity: a high risk to auditory function that needs to be monitored in drug development. Front Mol Neurosci 2024; 17:1379743. [PMID: 38756707 PMCID: PMC11096496 DOI: 10.3389/fnmol.2024.1379743] [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: 01/31/2024] [Accepted: 04/15/2024] [Indexed: 05/18/2024] Open
Abstract
Hearing loss constitutes a major global health concern impacting approximately 1.5 billion people worldwide. Its incidence is undergoing a substantial surge with some projecting that by 2050, a quarter of the global population will experience varying degrees of hearing deficiency. Environmental factors such as aging, exposure to loud noise, and the intake of ototoxic medications are implicated in the onset of acquired hearing loss. Ototoxicity resulting in inner ear damage is a leading cause of acquired hearing loss worldwide. This could be minimized or avoided by early testing of hearing functions in the preclinical phase of drug development. While the assessment of ototoxicity is well defined for drug candidates in the hearing field - required for drugs that are administered by the otic route and expected to reach the middle or inner ear during clinical use - ototoxicity testing is not required for all other therapeutic areas. Unfortunately, this has resulted in more than 200 ototoxic marketed medications. The aim of this publication is to raise awareness of drug-induced ototoxicity and to formulate some recommendations based on available guidelines and own experience. Ototoxicity testing programs should be adapted to the type of therapy, its indication (targeting the ear or part of other medications classes being potentially ototoxic), and the number of assets to test. For multiple molecules and/or multiple doses, screening options are available: in vitro (otic cell assays), ex vivo (cochlear explant), and in vivo (in zebrafish). In assessing the ototoxicity of a candidate drug, it is good practice to compare its ototoxicity to that of a well-known control drug of a similar class. Screening assays provide a streamlined and rapid method to know whether a drug is generally safe for inner ear structures. Mammalian animal models provide a more detailed characterization of drug ototoxicity, with a possibility to localize and quantify the damage using functional, behavioral, and morphological read-outs. Complementary histological measures are routinely conducted notably to quantify hair cells loss with cochleogram. Ototoxicity studies can be performed in rodents (mice, rats), guinea pigs and large species. However, in undertaking, or at the very least attempting, all preclinical investigations within the same species, is crucial. This encompasses starting with pharmacokinetics and pharmacology efficacy studies and extending through to toxicity studies. In life read-outs include Auditory Brainstem Response (ABR) and Distortion Product OtoAcoustic Emissions (DPOAE) measurements that assess the activity and integrity of sensory cells and the auditory nerve, reflecting sensorineural hearing loss. Accurate, reproducible, and high throughput ABR measures are fundamental to the quality and success of these preclinical trials. As in humans, in vivo otoscopic evaluations are routinely carried out to observe the tympanic membrane and auditory canal. This is often done to detect signs of inflammation. The cochlea is a tonotopic structure. Hair cell responsiveness is position and frequency dependent, with hair cells located close to the cochlea apex transducing low frequencies and those at the base transducing high frequencies. The cochleogram aims to quantify hair cells all along the cochlea and consequently determine hair cell loss related to specific frequencies. This measure is then correlated with the ABR & DPOAE results. Ototoxicity assessments evaluate the impact of drug candidates on the auditory and vestibular systems, de-risk hearing loss and balance disorders, define a safe dose, and optimize therapeutic benefits. These types of studies can be initiated during early development of a therapeutic solution, with ABR and otoscopic evaluations. Depending on the mechanism of action of the compound, studies can include DPOAE and cochleogram. Later in the development, a GLP (Good Laboratory Practice) ototoxicity study may be required based on otic related route of administration, target, or known potential otic toxicity.
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Herb M. NADPH Oxidase 3: Beyond the Inner Ear. Antioxidants (Basel) 2024; 13:219. [PMID: 38397817 PMCID: PMC10886416 DOI: 10.3390/antiox13020219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 02/25/2024] Open
Abstract
Reactive oxygen species (ROS) were formerly known as mere byproducts of metabolism with damaging effects on cellular structures. The discovery and description of NADPH oxidases (Nox) as a whole enzyme family that only produce this harmful group of molecules was surprising. After intensive research, seven Nox isoforms were discovered, described and extensively studied. Among them, the NADPH oxidase 3 is the perhaps most underrated Nox isoform, since it was firstly discovered in the inner ear. This stigma of Nox3 as "being only expressed in the inner ear" was also used by me several times. Therefore, the question arose whether this sentence is still valid or even usable. To this end, this review solely focuses on Nox3 and summarizes its discovery, the structural components, the activating and regulating factors, the expression in cells, tissues and organs, as well as the beneficial and detrimental effects of Nox3-mediated ROS production on body functions. Furthermore, the involvement of Nox3-derived ROS in diseases progression and, accordingly, as a potential target for disease treatment, will be discussed.
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Affiliation(s)
- Marc Herb
- Institute for Medical Microbiology, Immunology and Hygiene, Faculty of Medicine, University Hospital Cologne, University of Cologne, 50935 Cologne, Germany;
- German Centre for Infection Research, Partner Site Bonn-Cologne, 50931 Cologne, Germany
- Cologne Cluster of Excellence on Cellular Stress Responses in Aging-Associated Diseases (CECAD), 50931 Cologne, Germany
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3
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Verdoodt D, van Wijk E, Broekman S, Venselaar H, Aben F, Sels L, De Backer E, Gommeren H, Szewczyk K, Van Camp G, Ponsaerts P, Van Rompaey V, de Vrieze E. Rational design of a genomically humanized mouse model for dominantly inherited hearing loss, DFNA9. Hear Res 2024; 442:108947. [PMID: 38218018 DOI: 10.1016/j.heares.2023.108947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 12/04/2023] [Accepted: 12/30/2023] [Indexed: 01/15/2024]
Abstract
DFNA9 is a dominantly inherited form of adult-onset progressive hearing impairment caused by mutations in the COCH gene. COCH encodes cochlin, a crucial extracellular matrix protein. We established a genomically humanized mouse model for the Dutch/Belgian c.151C>T founder mutation in COCH. Considering upcoming sequence-specific genetic therapies, we exchanged the genomic murine Coch exons 3-6 for the corresponding human sequence. Introducing human-specific genetic information into mouse exons can be risky. To mitigate unforeseen consequences on cochlin function resulting from the introduction of the human COCH protein-coding sequence, we converted all human-specific amino acids to mouse equivalents. We furthermore optimized the recognition of the human COCH exons by the murine splicing machinery during pre-mRNA splicing. Subsequent observations in mouse embryonic stem cells revealed correct splicing of the hybrid Coch transcript. The inner ear of the established humanized Coch mice displays correctly-spliced wild-type and mutant humanized Coch alleles. For a comprehensive study of auditory function, mice were crossbred with C57BL/6 Cdh23753A>G mice to remove the Cdh23ahl allele from the genetic background of the mice. At 9 months, all humanized Coch genotypes showed hearing thresholds comparable to wild-type C57BL/6 Cdh23753A>G mice. This indicates that both the introduction of human wildtype COCH, and correction of Cdh23ahl in the humanized Coch lines was successful. Overall, our approach proved beneficial in eliminating potential adverse events of genomic humanization of mouse genes, and provides us with a model in which sequence-specific therapies directed against the human mutant COCH alle can be investigated. With the hearing and balance defects anticipated to occur late in the second year of life, a long-term follow-up study is ongoing to fully characterize the humanized Coch mouse model.
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Affiliation(s)
- Dorien Verdoodt
- Department of Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium; Laboratory of Experimental Hematology, Vaccine and Infectious Disease Institute (Vaxinfectio), University of Antwerp, Antwerp, Belgium
| | - Erwin van Wijk
- Department of Otorhinolaryngology, Hearing and Genes, Radboud University Medical Center, Nijmegen, GA 6525, the Netherlands
| | - Sanne Broekman
- Department of Otorhinolaryngology, Hearing and Genes, Radboud University Medical Center, Nijmegen, GA 6525, the Netherlands
| | - Hanka Venselaar
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, GA 6525, the Netherlands
| | - Fien Aben
- Department of Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium; Department of Otorhinolaryngology, Hearing and Genes, Radboud University Medical Center, Nijmegen, GA 6525, the Netherlands
| | - Lize Sels
- Department of Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - Evi De Backer
- Department of Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium; Department of Otorhinolaryngology and Head & Neck Surgery, Antwerp University Hospital, Antwerp, Belgium
| | - Hanne Gommeren
- Department of Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - Krystyna Szewczyk
- Department of Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - Guy Van Camp
- Center for Medical Genetics, University of Antwerp, Antwerp 2000, Belgium
| | - Peter Ponsaerts
- Laboratory of Experimental Hematology, Vaccine and Infectious Disease Institute (Vaxinfectio), University of Antwerp, Antwerp, Belgium
| | - Vincent Van Rompaey
- Department of Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium; Department of Otorhinolaryngology and Head & Neck Surgery, Antwerp University Hospital, Antwerp, Belgium
| | - Erik de Vrieze
- Department of Otorhinolaryngology, Hearing and Genes, Radboud University Medical Center, Nijmegen, GA 6525, the Netherlands.
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Veithen M, Huyghe A, Van Den Ackerveken P, Fukada SI, Kokubo H, Breuskin I, Nguyen L, Delacroix L, Malgrange B. Sox9 Inhibits Cochlear Hair Cell Fate by Upregulating Hey1 and HeyL Antagonists of Atoh1. Cells 2023; 12:2148. [PMID: 37681879 PMCID: PMC10486728 DOI: 10.3390/cells12172148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 08/23/2023] [Accepted: 08/24/2023] [Indexed: 09/09/2023] Open
Abstract
It is widely accepted that cell fate determination in the cochlea is tightly controlled by different transcription factors (TFs) that remain to be fully defined. Here, we show that Sox9, initially expressed in the entire sensory epithelium of the cochlea, progressively disappears from differentiating hair cells (HCs) and is finally restricted to supporting cells (SCs). By performing ex vivo electroporation of E13.5-E14.5 cochleae, we demonstrate that maintenance of Sox9 expression in the progenitors committed to HC fate blocks their differentiation, even if co-expressed with Atoh1, a transcription factor necessary and sufficient to form HC. Sox9 inhibits Atoh1 transcriptional activity by upregulating Hey1 and HeyL antagonists, and genetic ablation of these genes induces extra HCs along the cochlea. Although Sox9 suppression from sensory progenitors ex vivo leads to a modest increase in the number of HCs, it is not sufficient in vivo to induce supernumerary HC production in an inducible Sox9 knockout model. Taken together, these data show that Sox9 is downregulated from nascent HCs to allow the unfolding of their differentiation program. This may be critical for future strategies to promote fully mature HC formation in regeneration approaches.
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Affiliation(s)
- Mona Veithen
- Laboratory of Developmental Neurobiology, GIGA-Neurosciences, University of Liege, 4000 Liege, Belgium; (M.V.); (A.H.); (P.V.D.A.); (I.B.); (L.D.)
| | - Aurélia Huyghe
- Laboratory of Developmental Neurobiology, GIGA-Neurosciences, University of Liege, 4000 Liege, Belgium; (M.V.); (A.H.); (P.V.D.A.); (I.B.); (L.D.)
| | - Priscilla Van Den Ackerveken
- Laboratory of Developmental Neurobiology, GIGA-Neurosciences, University of Liege, 4000 Liege, Belgium; (M.V.); (A.H.); (P.V.D.A.); (I.B.); (L.D.)
| | - So-ichiro Fukada
- Laboratory of Stem Cell Regeneration and Adaptation, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka 565-0871, Japan;
| | - Hiroki Kokubo
- Graduate School of Biomedical and Health Sciences, 1-2-3 Kasumi, Minamiku, Hiroshima 734-8551, Japan;
| | - Ingrid Breuskin
- Laboratory of Developmental Neurobiology, GIGA-Neurosciences, University of Liege, 4000 Liege, Belgium; (M.V.); (A.H.); (P.V.D.A.); (I.B.); (L.D.)
| | - Laurent Nguyen
- Laboratory of Molecular Regulation of Neurogenesis, GIGA-Neurosciences, University of Liege, 4000 Liege, Belgium;
| | - Laurence Delacroix
- Laboratory of Developmental Neurobiology, GIGA-Neurosciences, University of Liege, 4000 Liege, Belgium; (M.V.); (A.H.); (P.V.D.A.); (I.B.); (L.D.)
| | - Brigitte Malgrange
- Laboratory of Developmental Neurobiology, GIGA-Neurosciences, University of Liege, 4000 Liege, Belgium; (M.V.); (A.H.); (P.V.D.A.); (I.B.); (L.D.)
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5
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Fritzsche S, Strauss C, Scheller C, Leisz S. Nimodipine Treatment Protects Auditory Hair Cells from Cisplatin-Induced Cell Death Accompanied by Upregulation of LMO4. Int J Mol Sci 2022; 23:ijms23105780. [PMID: 35628594 PMCID: PMC9145067 DOI: 10.3390/ijms23105780] [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: 04/12/2022] [Revised: 05/17/2022] [Accepted: 05/19/2022] [Indexed: 12/04/2022] Open
Abstract
Ototoxicity is one of the main dose-limiting side effects of cisplatin chemotherapy and impairs the quality of life of tumor patients dramatically. Since there is currently no established standard therapy targeting hearing loss in cisplatin treatment, the aim of this study was to investigate the effect of nimodipine and its role in cell survival in cisplatin-associated hearing cell damage. To determine the cytotoxic effect, the cell death rate was measured using undifferentiated and differentiated UB/OC−1 and UB/OC−2 cells, after nimodipine pre-treatment and stress induction by cisplatin. Furthermore, immunoblot analysis and intracellular calcium measurement were performed to investigate anti-apoptotic signaling, which was associated with a reduced cytotoxic effect after nimodipine pre-treatment. Cisplatin’s cytotoxic effect was significantly attenuated by nimodipine up to 61%. In addition, nimodipine pre-treatment counteracted the reduction in LIM Domain Only 4 (LMO4) by cisplatin, which was associated with increased activation of Ak strain transforming/protein kinase B (Akt), cAMP response element-binding protein (CREB), and signal transducers and activators of transcription 3 (Stat3). Thus, nimodipine presents a potentially well-tolerated substance against the ototoxicity of cisplatin, which could result in a significant improvement in patients’ quality of life.
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6
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Lee MP, Waldhaus J. In vitro and in vivo models: What have we learnt about inner ear regeneration and treatment for hearing loss? Mol Cell Neurosci 2022; 120:103736. [PMID: 35577314 PMCID: PMC9551661 DOI: 10.1016/j.mcn.2022.103736] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 04/29/2022] [Accepted: 05/10/2022] [Indexed: 01/07/2023] Open
Abstract
The sensory cells of the inner ear, called hair cells, do not regenerate spontaneously and therefore, hair cell loss and subsequent hearing loss are permanent in humans. Conversely, functional hair cell regeneration can be observed in non-mammalian vertebrate species like birds and fish. Also, during postnatal development in mice, limited regenerative capacity and the potential to isolate stem cells were reported. Together, these findings spurred the interest of current research aiming to investigate the endogenous regenerative potential in mammals. In this review, we summarize current in vitro based approaches and briefly introduce different in vivo model organisms utilized to study hair cell regeneration. Furthermore, we present an overview of the findings that were made synergistically using both, the in vitro and in vivo based tools.
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Affiliation(s)
- Mary P Lee
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Joerg Waldhaus
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI 48109, USA.
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7
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In focus in HCB. Histochem Cell Biol 2022; 157:389-391. [DOI: 10.1007/s00418-022-02097-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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8
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Kakuki T, Kohno T, Nishida S, Konno T, Kikuchi S, Ohwada K, Nakano M, Tezuka M, Takano K, Kojima T. FOXO3/TGF-β signal-dependent ciliogenesis and cell functions during differentiation of temperature-sensitive mouse cochlear precursor hair cells. Histochem Cell Biol 2022; 157:415-426. [PMID: 35024955 DOI: 10.1007/s00418-021-02068-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2021] [Indexed: 12/29/2022]
Abstract
The transcription factor FOXO3 is necessary to preserve cochlear hair cells. Growth factors, including TGF-β, closely contribute to cochlear hair cell regeneration. In the present study, to investigate the roles of FOXO3 in the ciliogenesis and cell functions of cochlear hair cells, UB/OC-2 temperature-sensitive mouse cochlear precursor hair cells were treated with TGF-β receptor type 1 inhibitor EW-7197 or EGF receptor inhibitor AG-1478 after transfection with or without siRNA-FOXO3a. GeneChip analysis revealed that treatment with EW-7197 increased Foxo3 genes and decreased genes of Smads. During cell differentiation, treatment with EW-7197 or AG-1478 induced an increase in length of cilia-like structures that were positive for acetylated tubulin and inhibited cell migration. Treatment with EW-7197 also increased cell metabolism measured as mitochondrial basal respiration (oxygen consumption rate). The effects of EW-7197 were stronger than those of AG-1478. Knockdown of FOXO3 prevented the growth of cilia-like structures induced by EW-7197 or AG-1478 and induced cell migration under treatment with EW-7197. No change of the epithelial cell polarity molecule PAR3 was observed with any treatment. Treatment with the antimicrobial agent amikacin prevented the growth of cilia-like structures induced by EW-7197 and induced apoptosis. Pretreatment with the glucocorticoid dexamethasone inhibited the apoptosis induced by amikacin. This in vitro model of mouse cochlear hair cells suggests that FOXO3/TGF-β signaling plays a crucial role in ciliogenesis and cell functions during differentiation of cochlear hair cells. This model is useful for analysis of the mechanisms of hearing loss and to find therapeutic agents to prevent it.
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Affiliation(s)
- Takuya Kakuki
- Department of Otolaryngology, Sapporo Medical University School of Medicine, Sapporo, 060-8556, Japan
| | - Takayuki Kohno
- Department of Cell Science, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, South-1, West-17, Chuo-ku, Sapporo, 060-8556, Japan.
| | - Soshi Nishida
- Department of Otolaryngology, Sapporo Medical University School of Medicine, Sapporo, 060-8556, Japan.,Department of Cell Science, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, South-1, West-17, Chuo-ku, Sapporo, 060-8556, Japan
| | - Takumi Konno
- Department of Cell Science, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, South-1, West-17, Chuo-ku, Sapporo, 060-8556, Japan
| | - Shin Kikuchi
- Department of Anatomy, Sapporo Medical University School of Medicine, Sapporo, 060-8556, Japan
| | - Kizuku Ohwada
- Department of Otolaryngology, Sapporo Medical University School of Medicine, Sapporo, 060-8556, Japan.,Department of Cell Science, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, South-1, West-17, Chuo-ku, Sapporo, 060-8556, Japan
| | - Masaya Nakano
- Department of Otolaryngology, Sapporo Medical University School of Medicine, Sapporo, 060-8556, Japan.,Department of Cell Science, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, South-1, West-17, Chuo-ku, Sapporo, 060-8556, Japan
| | - Mitsuki Tezuka
- Department of Cell Science, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, South-1, West-17, Chuo-ku, Sapporo, 060-8556, Japan
| | - Kenichi Takano
- Department of Otolaryngology, Sapporo Medical University School of Medicine, Sapporo, 060-8556, Japan
| | - Takashi Kojima
- Department of Cell Science, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, South-1, West-17, Chuo-ku, Sapporo, 060-8556, Japan.
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9
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Gómez-Dorado M, Daudet N, Gale JE, Dawson SJ. Differential regulation of mammalian and avian ATOH1 by E2F1 and its implication for hair cell regeneration in the inner ear. Sci Rep 2021; 11:19368. [PMID: 34588543 PMCID: PMC8481459 DOI: 10.1038/s41598-021-98816-w] [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: 06/04/2020] [Accepted: 08/31/2021] [Indexed: 12/23/2022] Open
Abstract
The mammalian inner ear has a limited capacity to regenerate its mechanosensory hair cells. This lack of regenerative capacity underlies the high incidence of age-related hearing loss in humans. In contrast, non-mammalian vertebrates can form new hair cells when damage occurs, a mechanism that depends on re-activation of expression of the pro-hair cell transcription factor Atoh1. Here, we show that members of the E2F transcription factor family, known to play a key role in cell cycle progression, regulate the expression of Atoh1. E2F1 activates chicken Atoh1 by directly interacting with a cis-regulatory region distal to the avian Atoh1 gene. E2F does not activate mouse Atoh1 gene expression, since this regulatory element is absent in mammals. We also show that E2F1 expression changes dynamically in the chicken auditory epithelium during ototoxic damage and hair cell regeneration. Therefore, we propose a model in which the mitotic regeneration of non-mammalian hair cells is due to E2F1-mediated activation of Atoh1 expression, a mechanism which has been lost in mammals.
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Affiliation(s)
| | - Nicolas Daudet
- UCL Ear Institute, 332 Gray's Inn Road, London, WC1X 8EE, UK
| | - Jonathan E Gale
- UCL Ear Institute, 332 Gray's Inn Road, London, WC1X 8EE, UK
| | - Sally J Dawson
- UCL Ear Institute, 332 Gray's Inn Road, London, WC1X 8EE, UK.
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Role of Oxidative Stress in the Senescence Pattern of Auditory Cells in Age-Related Hearing Loss. Antioxidants (Basel) 2021; 10:antiox10091497. [PMID: 34573129 PMCID: PMC8464759 DOI: 10.3390/antiox10091497] [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: 08/12/2021] [Revised: 09/09/2021] [Accepted: 09/18/2021] [Indexed: 01/10/2023] Open
Abstract
Age-related hearing loss (ARHL) is an increasing and gradual sensorineural hearing dysfunction. Oxidative stress is an essential factor in developing ARHL; additionally, premature senescence of auditory cells induced by oxidative stress can produce hearing loss. Hydrogen peroxide (H2O2) represents a method commonly used to generate cellular senescence in vitro. The objective of the present paper is to study H2O2-induced senescence patterns in three auditory cell lines (House Ear Institute-Organ of Corti 1, HEI-OC1; organ of Corti, OC-k3, and stria vascularis, SV-k1 cells) to elucidate the intrinsic mechanisms responsible for ARHL. The auditory cells were exposed to H2O2 at different concentrations and times. The results obtained show different responses of the hearing cells concerning cell growth, β-galactosidase activity, morphological changes, mitochondrial activation, levels of oxidative stress, and other markers of cell damage (Forkhead box O3a, FoxO3a, and 8-oxoguanine, 8-oxoG). Comparison between the responses of these auditory cells to H2O2 is a helpful method to evaluate the molecular mechanisms responsible for these auditory cells' senescence. Furthermore, this in vitro model could help develop anti-senescent therapeutic strategies for the treatment of AHRL.
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Coffin AB, Boney R, Hill J, Tian C, Steyger PS. Detecting Novel Ototoxins and Potentiation of Ototoxicity by Disease Settings. Front Neurol 2021; 12:725566. [PMID: 34489859 PMCID: PMC8418111 DOI: 10.3389/fneur.2021.725566] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 07/22/2021] [Indexed: 12/24/2022] Open
Abstract
Over 100 drugs and chemicals are associated with permanent hearing loss, tinnitus, and vestibular deficits, collectively known as ototoxicity. The ototoxic potential of drugs is rarely assessed in pre-clinical drug development or during clinical trials, so this debilitating side-effect is often discovered as patients begin to report hearing loss. Furthermore, drug-induced ototoxicity in adults, and particularly in elderly patients, may go unrecognized due to hearing loss from a variety of etiologies because of a lack of baseline assessments immediately prior to novel therapeutic treatment. During the current pandemic, there is an intense effort to identify new drugs or repurpose FDA-approved drugs to treat COVID-19. Several potential COVID-19 therapeutics are known ototoxins, including chloroquine (CQ) and lopinavir-ritonavir, demonstrating the necessity to identify ototoxic potential in existing and novel medicines. Furthermore, several factors are emerging as potentiators of ototoxicity, such as inflammation (a hallmark of COVID-19), genetic polymorphisms, and ototoxic synergy with co-therapeutics, increasing the necessity to evaluate a drug's potential to induce ototoxicity under varying conditions. Here, we review the potential of COVID-19 therapies to induce ototoxicity and factors that may compound their ototoxic effects. We then discuss two models for rapidly detecting the potential for ototoxicity: mammalian auditory cell lines and the larval zebrafish lateral line. These models offer considerable value for pre-clinical drug development, including development of COVID-19 therapies. Finally, we show the validity of in silico screening for ototoxic potential using a computational model that compares structural similarity of compounds of interest with a database of known ototoxins and non-ototoxins. Preclinical screening at in silico, in vitro, and in vivo levels can provide an earlier indication of the potential for ototoxicity and identify the subset of candidate therapeutics for treating COVID-19 that need to be monitored for ototoxicity as for other widely-used clinical therapeutics, like aminoglycosides and cisplatin.
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Affiliation(s)
| | | | - Jordan Hill
- Washington State University Vancouver, Vancouver, WA, United States
| | - Cong Tian
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, United States
| | - Peter S. Steyger
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, United States
- National Center for Rehabilitative Auditory Research, Portland, OR, United States
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12
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Dhukhwa A, Al Aameri RFH, Sheth S, Mukherjea D, Rybak L, Ramkumar V. Regulator of G protein signaling 17 represents a novel target for treating cisplatin induced hearing loss. Sci Rep 2021; 11:8116. [PMID: 33854102 PMCID: PMC8046767 DOI: 10.1038/s41598-021-87387-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/26/2021] [Indexed: 12/28/2022] Open
Abstract
Regulators of G protein signaling (RGS) accelerate the GTPase activity of G proteins to enable rapid termination of the signals triggered by G protein-coupled receptors (GPCRs). Activation of several GPCRs, including cannabinoid receptor 2 (CB2R) and adenosine A1 receptor (A1AR), protects against noise and drug-induced ototoxicity. One such drug, cisplatin, an anticancer agent used to treat various solid tumors, produces permanent hearing loss in experimental animals and in a high percentage of cancer patients who undergo treatments. In this study we show that cisplatin induces the expression of the RGS17 gene and increases the levels of RGS17 protein which contributes to a significant proportion of the hearing loss. Knockdown of RGS17 suppressed cisplatin-induced hearing loss in male Wistar rats, while overexpression of RGS17 alone produced hearing loss in vivo. Furthermore, RGS17 and CB2R negatively regulate the expression of each other. These data suggest that RGS17 mediates cisplatin ototoxicity by uncoupling cytoprotective GPCRs from their normal G protein interactions, thereby mitigating the otoprotective contributions of endogenous ligands of these receptors. Thus, RGS17 represents a novel mediator of cisplatin ototoxicity and a potential therapeutic target for treating hearing loss.
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Affiliation(s)
- Asmita Dhukhwa
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, 62702, USA
| | - Raheem F H Al Aameri
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, 62702, USA
| | - Sandeep Sheth
- Department of Pharmaceutical Sciences, Larkin University College of Pharmacy, Miami, FL, 33169, USA
| | - Debashree Mukherjea
- Department of Otolaryngology, Southern Illinois University School of Medicine, Springfield, IL, 62702, USA
| | - Leonard Rybak
- Department of Otolaryngology, Southern Illinois University School of Medicine, Springfield, IL, 62702, USA
| | - Vickram Ramkumar
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, 62702, USA.
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13
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Fetoni AR, Astolfi L. Cisplatin ototoxicity and role of antioxidant on its prevention. HEARING, BALANCE AND COMMUNICATION 2020. [DOI: 10.1080/21695717.2020.1810962] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Anna Rita Fetoni
- Department of Head and Neck Surgery, Fondazione Policlinico Universitario A. Gemelli IRCCS, Università Cattolica del Sacro Cuore, Roma, Italia
| | - Laura Astolfi
- Bioacoustics Research Laboratory, Department of Neuroscience, University of Padua, Padua, Italy
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14
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Otoprotective Effect of 2,3,4',5-Tetrahydroxystilbene-2- O-β-d-Glucoside on Gentamicin-Induced Apoptosis in Mouse Cochlear UB/OC-2 Cells. Molecules 2020; 25:molecules25133070. [PMID: 32640539 PMCID: PMC7412181 DOI: 10.3390/molecules25133070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/03/2020] [Accepted: 07/05/2020] [Indexed: 02/06/2023] Open
Abstract
Excessive levels of reactive oxygen species (ROS) lead to mitochondrial damage and apoptotic cell death in gentamicin-induced ototoxicity. 2,3,4',5-Tetrahydroxystilbene-2-O-β-d-glucoside (THSG), a bioactive constituent, isolated from Polygonum multiflorum Thunb., exhibits numerous biological benefits in treating aging-related diseases by suppressing oxidative damage. However, its protective effect on gentamicin-induced ototoxicity remains unexplored. Therefore, here, we aimed to investigate the otoprotective effect of THSG on gentamicin-induced apoptosis in mouse cochlear UB/OC-2 cells. We evaluated the effect of gentamicin and THSG on the ROS level, superoxide dismutase (SOD) activity, mitochondrial membrane potential, nuclear condensation, and lactate dehydrogenase (LDH) release, and the expression of apoptosis-related proteins was assessed to understand the molecular mechanisms underlying its preventive effects. The findings demonstrated that gentamicin increased ROS generation, LDH release, and promoted apoptotic cell death in UB/OC-2 cells. However, THSG treatment reversed these effects by suppressing ROS production and downregulating the mitochondrial-dependent apoptotic pathway. Additionally, it increased the SOD activity, decreased the expression of apoptosis-related proteins, alleviated the levels of the apoptotic cells, and impaired cytotoxicity. To the best of our knowledge, this is the first study to demonstrate that THSG could be a potential therapeutic option to attenuate gentamicin-induced ototoxicity.
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15
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Kojima K, Nishida AT, Tashiro K, Hirota K, Nishio T, Murata M, Kato N, Kawaguchi S, Zine A, Ito J, Van De Water TR. Isolation and Characterization of Mammalian Otic Progenitor Cells that Can Differentiate into Both Sensory Epithelial and Neuronal Cell Lineages. Anat Rec (Hoboken) 2020; 303:451-460. [PMID: 31943808 DOI: 10.1002/ar.24335] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 11/25/2019] [Accepted: 12/03/2019] [Indexed: 01/01/2023]
Abstract
The mammalian inner ear mediates hearing and balance and during development generates both cochleo-vestibular ganglion neurons and sensory epithelial receptor cells, that is, hair cells and support cells. Cell marking experiments have shown that both hair cells and support cells can originate from a common progenitor. Here, we demonstrate the lineage potential of individual otic epithelial cell clones using three cell lines established by a combination of limiting dilution and gene-marking techniques from an embryonic day 12 (E12) rat otocyst. Cell-type specific marker analyses of these clonal lines under proliferation and differentiation culture conditions demonstrate that during differentiation immature cell markers (Nanog and Nestin) were downregulated and hair cell (Myosin VIIa and Math1), support cell (p27Kip1 and cytokeratin) and neuronal cell (NF-H and NeuroD) markers were upregulated. Our results suggest that the otic epithelium of the E12 mammalian inner ear possess multipotent progenitor cells able to generate cell types of both sensory epithelial and neural cell lineages when cultured under a differentiation culture condition. Understanding the molecular mechanisms of proliferation and differentiation of multipotent otic progenitor cells may provide insights that could contribute to the development of a novel cell therapy with a potential to initiate or stimulate the sensorineural repair of damaged inner ear sensory receptors. Anat Rec, 303:451-460, 2020. © 2019 American Association for Anatomy.
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Affiliation(s)
- Ken Kojima
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,University of Miami Ear Institute, Department of Otolaryngology, University of Miami School of Medicine, Miami, Florida.,Department of Integrative Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Akiko T Nishida
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,Department of Medical Chemistry, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,Center for Molecular Biology and Genetics, Kyoto University, Kyoto, Japan
| | - Kei Tashiro
- Center for Molecular Biology and Genetics, Kyoto University, Kyoto, Japan
| | - Kiichi Hirota
- BioMedical Special Research Unit, Human Stress Signal Research Center, National Institute of Advanced Industrial Science and Technology, Ikeda, Japan
| | - Takeshi Nishio
- Department of Integrative Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Miyahiko Murata
- Department of Integrative Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Nobuo Kato
- Department of Integrative Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Saburo Kawaguchi
- Department of Integrative Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Azel Zine
- Institute of Neuroscience, INSERM U. 583, University of Montpellier I, Montpellier, France
| | - Juichi Ito
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Thomas R Van De Water
- University of Miami Ear Institute, Department of Otolaryngology, University of Miami School of Medicine, Miami, Florida
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16
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Drug-induced Stress Granule Formation Protects Sensory Hair Cells in Mouse Cochlear Explants During Ototoxicity. Sci Rep 2019; 9:12501. [PMID: 31467369 PMCID: PMC6715625 DOI: 10.1038/s41598-019-48393-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 07/22/2019] [Indexed: 01/08/2023] Open
Abstract
Stress granules regulate RNA translation during cellular stress, a mechanism that is generally presumed to be protective, since stress granule dysregulation caused by mutation or ageing is associated with neurodegenerative disease. Here, we investigate whether pharmacological manipulation of the stress granule pathway in the auditory organ, the cochlea, affects the survival of sensory hair cells during aminoglycoside ototoxicity, a common cause of acquired hearing loss. We show that hydroxamate (-)-9, a silvestrol analogue that inhibits eIF4A, induces stress granule formation in both an auditory cell line and ex-vivo cochlear cultures and that it prevents ototoxin-induced hair-cell death. In contrast, preventing stress granule formation using the small molecule inhibitor ISRIB increases hair-cell death. Furthermore, we provide the first evidence of stress granule formation in mammalian hair cells in-vivo triggered by aminoglycoside treatment. Our results demonstrate that pharmacological induction of stress granules enhances cell survival in native-tissue, in a clinically-relevant context. This establishes stress granules as a viable therapeutic target not only for hearing loss but also other neurodegenerative diseases.
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17
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Rathinam R, Rosati R, Jamesdaniel S. CRISPR/Cas9-mediated knockout of Lim-domain only four retards organ of Corti cell growth. J Cell Biochem 2018; 119:3545-3553. [PMID: 29143984 DOI: 10.1002/jcb.26529] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 11/13/2017] [Indexed: 01/04/2023]
Abstract
Lim-domain only 4 (LMO4) plays a critical role in mediating the ototoxic side-effects of cisplatin, a highly effective anti-cancer drug. However, the signaling mechanism by which cochlear LMO4 mediates otopathology is yet to be fully understood. Knockout cell culture models are useful tools for investigating the functional roles of novel genes and delineating associated signaling pathways. Therefore, LMO4 knockout organ of Corti cells were generated by using the CRISPR (clustered regularly interspersed short palindromic repeats)/Cas9 (CRISPR-associated protein 9) system. Successful knockout of LMO4 in UB/OC1 cells was verified by the absence of LMO4 protein bands in immunoblots. Though the Knockout of LMO4 retarded the growth rate and the migratory potential of the cells it did not inhibit their long-term viability as the LMO4 knockout UB/OC1 cells were able to survive, proliferate, and form colonies. In addition, the knockout of LMO4 did not alter the expression of myosin VIIa, a biomarker of hair cells, suggesting that the knockout cells retain important characteristic features of cochlear sensory receptor cells. Thus, the findings of this study indicate that CRISPR/Cas9 system is a simple and versatile method for knocking out genes of interest in organ of Corti cells and that LMO4 knockout UB/OC1 cells are viable experimental models for studying the functional role of LMO4 in ototoxicity.
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Affiliation(s)
- Rajamani Rathinam
- Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan
| | - Rita Rosati
- Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan
| | - Samson Jamesdaniel
- Institute of Environmental Health Sciences, Wayne State University, Detroit, Michigan.,Department of Family Medicine and Public Health Sciences, Wayne State University, Detroit, Michigan
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18
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Van den Ackerveken P, Mounier A, Huyghe A, Sacheli R, Vanlerberghe PB, Volvert ML, Delacroix L, Nguyen L, Malgrange B. The miR-183/ItgA3 axis is a key regulator of prosensory area during early inner ear development. Cell Death Differ 2017; 24:2054-2065. [PMID: 28777373 DOI: 10.1038/cdd.2017.127] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 06/15/2017] [Accepted: 06/30/2017] [Indexed: 01/08/2023] Open
Abstract
MicroRNAs are important regulators of gene expression and are involved in cellular processes such as proliferation or differentiation, particularly during development of numerous organs including the inner ear. However, it remains unknown if miRNAs are required during the earliest stages of otocyst and cochlear duct development. Here, we report that a conditional loss of Dicer expression in the otocyst impairs the early development of the inner ear as a result of the accumulation of DNA damage that trigger p53-mediated apoptosis. Moreover, cochlear progenitors in the prosensory domain do not exit the cell cycle. Our unbiased approach identified ItgA3 as a target of miR-183, which are both enriched in the otic vesicle. We observed that the repression of integrin alpha 3 by miR-183 controls cell proliferation in the developing cochlea. Collectively, our results reveal that Dicer and miRNAs play essential roles in the regulation of early inner ear development.
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Affiliation(s)
- Priscilla Van den Ackerveken
- GIGA-Neurosciences, Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège B-4000, Belgium
| | - Anaïs Mounier
- GIGA-Neurosciences, Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège B-4000, Belgium
| | - Aurelia Huyghe
- GIGA-Neurosciences, Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège B-4000, Belgium
| | - Rosalie Sacheli
- GIGA-Neurosciences, Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège B-4000, Belgium
| | - Pierre-Bernard Vanlerberghe
- GIGA-Neurosciences, Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège B-4000, Belgium
| | - Marie-Laure Volvert
- GIGA-Neurosciences, Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège B-4000, Belgium
| | - Laurence Delacroix
- GIGA-Neurosciences, Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège B-4000, Belgium
| | - Laurent Nguyen
- GIGA-Neurosciences, Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège B-4000, Belgium
| | - Brigitte Malgrange
- GIGA-Neurosciences, Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège B-4000, Belgium
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19
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Minich RR, Li J, Tempel BL. Early growth response protein 1 regulates promoter activity of α-plasma membrane calcium ATPase 2, a major calcium pump in the brain and auditory system. BMC Mol Biol 2017; 18:14. [PMID: 28532435 PMCID: PMC5441030 DOI: 10.1186/s12867-017-0092-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 05/08/2017] [Indexed: 12/28/2022] Open
Abstract
Background Along with sodium/calcium (Ca2+) exchangers, plasma membrane Ca2+ ATPases (ATP2Bs) are main regulators of intracellular Ca2+ levels. There are four ATP2B paralogs encoded by four different genes. Atp2b2 encodes the protein pump with the fastest activation, ATP2B2. In mice, the Atp2b2 transcript has several alternate transcriptional start site variants: α, β, µ and δ. These variants are expressed in developmental and tissue specific manners. The α and β Atp2b2 transcripts are equally expressed in the brain. αAtp2b2 is the only transcript found in the outer hair cells of young mice (Silverstein RS, Tempel BL. in Neuroscience 141:245–257, 2006). Mutations in the coding region of the mouse Atp2b2 gene indicate a narrow window for tolerated dysfunction of the ATP2B2 protein, specifically in the auditory system. This highlights the necessity of tight regulation of this gene for normal cell physiology. Results Although ATP2Bs are important regulators of Ca2+ in many cell types, little is known about their transcriptional regulation. This study identifies the proximal promoter of the αAtp2b2 transcript. Further investigations indicate that ATOH1 and EGR1 modulate promoter activity. Additionally, we report that EGR1 increases endogenous expression of Atp2b2 transcript in two cell lines. Electrophoretic mobility shift assays (EMSA) indicate that EGR1 binds to a specific site in the CpG island of the αAtp2b2 promoter. Conclusion This study furthers our understanding of Atp2b2 regulation by: (I) elucidating transcriptional regulatory mechanisms for Atp2b2, and (II) identifying transcription factors that modulate expression of Atp2b2 in the brain and peripheral auditory system and (III) allows for future studies modulating gene expression of Atp2b2. Electronic supplementary material The online version of this article (doi:10.1186/s12867-017-0092-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rebecca R Minich
- Department of Pharmacology, School of Medicine, University of Washington, Seattle, WA, 98195, USA.
| | - Jin Li
- Department of Pharmacology, School of Medicine, University of Washington, Seattle, WA, 98195, USA
| | - Bruce L Tempel
- Department of Pharmacology, School of Medicine, University of Washington, Seattle, WA, 98195, USA. .,Department of Otolaryngology-HNS, School of Medicine, University of Washington, Box 357923, Seattle, WA, 98195, USA. .,Virginia Merrill Bloedel Hearing Research Center, School of Medicine, University of Washington, Seattle, WA, 98195, USA.
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20
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Bhavsar AP, Gunaretnam EP, Li Y, Hasbullah JS, Carleton BC, Ross CJD. Pharmacogenetic variants in TPMT alter cellular responses to cisplatin in inner ear cell lines. PLoS One 2017; 12:e0175711. [PMID: 28406961 PMCID: PMC5391095 DOI: 10.1371/journal.pone.0175711] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 03/30/2017] [Indexed: 11/19/2022] Open
Abstract
Cisplatin is a highly-effective and widely-used chemotherapeutic agent that causes ototoxicity in many patients. Pharmacogenomic studies of key genes controlling drug biotransformation identified variants in thiopurine methyltransferase (TPMT) as predictors of cisplatin-induced ototoxicity, although the mechanistic basis of this interaction has not been reported. Expression constructs of TPMT*3A, *3B and *3C variants were generated and monitored in cultured cells. Cellular TPMT*3A levels were detected at >20-fold lower amounts than the wild type confirming the unstable nature of this variant. The expression of wild type TPMT (TPMT*1) in two murine ear cell lines, HEI-OC1 and UB/OC-1, significantly mitigated their susceptibility to cisplatin toxicity. Cisplatin treatment induced Tlr4 gene expression in HEI-OC1 cells and this response was blunted by the expression of wild type TPMT but not TPMT*3A. In line with the significant mitigation of TPMT*1-expressing cells to cisplatin cytotoxicity, these findings demonstrate a drug-gene interaction between increased TPMT activity and decreased susceptibility to cisplatin-induced toxicity of inner ear cells.
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Affiliation(s)
- Amit P. Bhavsar
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, Canada
- BC Children’s Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Erandika P. Gunaretnam
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, Canada
- BC Children’s Hospital Research Institute, Vancouver, British Columbia, Canada
- Division of Translational Therapeutics, Department of Pediatrics, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Yuling Li
- BC Children’s Hospital Research Institute, Vancouver, British Columbia, Canada
- Division of Translational Therapeutics, Department of Pediatrics, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Jafar S. Hasbullah
- BC Children’s Hospital Research Institute, Vancouver, British Columbia, Canada
- Department of Medical Genetics, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Bruce C. Carleton
- BC Children’s Hospital Research Institute, Vancouver, British Columbia, Canada
- Division of Translational Therapeutics, Department of Pediatrics, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Colin J. D. Ross
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, Canada
- BC Children’s Hospital Research Institute, Vancouver, British Columbia, Canada
- * E-mail:
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21
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Targeting nitrative stress for attenuating cisplatin-induced downregulation of cochlear LIM domain only 4 and ototoxicity. Redox Biol 2016; 10:257-265. [PMID: 27821327 PMCID: PMC5099269 DOI: 10.1016/j.redox.2016.10.016] [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: 09/28/2016] [Revised: 10/03/2016] [Accepted: 10/12/2016] [Indexed: 01/17/2023] Open
Abstract
Cisplatin-induced ototoxicity remains a primary dose-limiting adverse effect of this highly effective anticancer drug. The clinical utility of cisplatin could be enhanced if the signaling pathways that regulate the toxic side-effects are delineated. In previous studies, we reported cisplatin-induced nitration of cochlear proteins and provided the first evidence for nitration and downregulation of cochlear LIM domain only 4 (LMO4) in cisplatin ototoxicity. Here, we extend these findings to define the critical role of nitrative stress in cisplatin-induced downregulation of LMO4 and its consequent ototoxic effects in UBOC1 cell cultures derived from sensory epithelial cells of the inner ear and in CBA/J mice. Cisplatin treatment increased the levels of nitrotyrosine and active caspase 3 in UBOC1 cells, which was detected by immunocytochemical and flow cytometry analysis, respectively. The cisplatin-induced nitrative stress and apoptosis were attenuated by co-treatment with SRI110, a peroxynitrite decomposition catalyst (PNDC), which also attenuated the cisplatin-induced downregulation of LMO4 in a dose-dependent manner. Furthermore, transient overexpression of LMO4 in UBOC1 cells prevented cisplatin-induced cytotoxicity while repression of LMO4 exacerbated cisplatin-induced cell death, indicating a direct link between LMO4 protein levels and cisplatin ototoxicity. Finally, auditory brainstem responses (ABR) recorded from CBA/J mice indicated that co-treatment with SRI110 mitigated cisplatin-induced hearing loss. Together, these results suggest that cisplatin-induced nitrative stress leads to a decrease in the levels of LMO4, downregulation of LMO4 is a critical determinant in cisplatin-induced ototoxicity, and targeting peroxynitrite could be a promising strategy for mitigating cisplatin-induced hearing loss. Cisplatin-induced nitrative stress leads to a decrease in the levels of LMO4. Downregulation of LMO4 is a critical factor in cisplatin-induced ototoxicity. SRI110 appears to be a promising candidate for preventing cisplatin ototoxicity.
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22
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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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23
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Kaur T, Borse V, Sheth S, Sheehan K, Ghosh S, Tupal S, Jajoo S, Mukherjea D, Rybak LP, Ramkumar V. Adenosine A1 Receptor Protects Against Cisplatin Ototoxicity by Suppressing the NOX3/STAT1 Inflammatory Pathway in the Cochlea. J Neurosci 2016; 36:3962-77. [PMID: 27053204 PMCID: PMC4821909 DOI: 10.1523/jneurosci.3111-15.2016] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 02/16/2016] [Accepted: 02/26/2016] [Indexed: 01/19/2023] Open
Abstract
Cisplatin is a commonly used antineoplastic agent that produces ototoxicity that is mediated in part by increasing levels of reactive oxygen species (ROS) via the NOX3 NADPH oxidase pathway in the cochlea. Recent studies implicate ROS generation in mediating inflammatory and apoptotic processes and hearing loss by activating signal transducer and activator of transcription (STAT1). In this study, we show that the adenosine A1 receptor (A1AR) protects against cisplatin ototoxicity by suppressing an inflammatory response initiated by ROS generation via NOX3 NADPH oxidase, leading to inhibition of STAT1. Trans-tympanic administration of the A1AR agonist R-phenylisopropyladenosine (R-PIA) inhibited cisplatin-induced ototoxicity, as measured by auditory brainstem responses and scanning electron microscopy in male Wistar rats. This was associated with reduced NOX3 expression, STAT1 activation, tumor necrosis factor-α (TNF-α) levels, and apoptosis in the cochlea. In vitro studies in UB/OC-1 cells, an organ of Corti immortalized cell line, showed that R-PIA reduced cisplatin-induced phosphorylation of STAT1 Ser(727) (but not Tyr(701)) and STAT1 luciferase activity by suppressing the ERK1/2, p38, and JNK mitogen-activated protein kinase (MAPK) pathways.R-PIA also decreased the expression of STAT1 target genes, such as TNF-α, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and reduced cisplatin-mediated apoptosis. These data suggest that the A1AR provides otoprotection by suppressing NOX3 and inflammation in the cochlea and could serve as an ideal target for otoprotective drug therapy. SIGNIFICANCE STATEMENT Cisplatin is a widely used chemotherapeutic agent for the treatment of solid tumors. Its use results in significant and permanent hearing loss, for which no US Food and Drug Administration-approved treatment is currently available. In this study, we targeted the cochlear adenosine A1 receptor (A1AR) by trans-tympanic injections of the agonist R-phenylisopropyladenosine (R-PIA) and showed that it reduced cisplatin-induced inflammation and apoptosis in the rat cochlea and preserved hearing. The mechanism of protection involves suppression of the NOX3 NADPH oxidase enzyme, a major target of cisplatin-induced reactive oxygen species (ROS) generation in the cochlea. ROS initiates an inflammatory and apoptotic cascade in the cochlea by activating STAT1 transcription factor, which is attenuated byR-PIA. Therefore, trans-tympanic delivery of A1AR agonists could effectively treat cisplatin ototoxicity.
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Affiliation(s)
- Tejbeer Kaur
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri 63110, and
| | | | | | - Kelly Sheehan
- Department of Surgery, Southern Illinois University School of Medicine, Springfield, Illinois 62794
| | | | | | | | - Debashree Mukherjea
- Department of Surgery, Southern Illinois University School of Medicine, Springfield, Illinois 62794
| | - Leonard P Rybak
- Department of Pharmacology and Department of Surgery, Southern Illinois University School of Medicine, Springfield, Illinois 62794
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Vetter DE, Basappa J. Multiplexed Isobaric Tagging Protocols for Quantitative Mass Spectrometry Approaches to Auditory Research. Methods Mol Biol 2016; 1427:109-33. [PMID: 27259924 DOI: 10.1007/978-1-4939-3615-1_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Modern biologists have at their disposal a large array of techniques used to assess the existence and relative or absolute quantity of any molecule of interest in a sample. However, implementing most of these procedures can be a daunting task for the first time, even in a lab with experienced researchers. Just choosing a protocol to follow can take weeks while all of the nuances are examined and it is determined whether a protocol will (a) give the desired results, (b) result in interpretable and unbiased data, and (c) be amenable to the sample of interest. We detail here a robust procedure for labeling proteins in a complex lysate for the ultimate differential quantification of protein abundance following experimental manipulations. Following a successful outcome of the labeling procedure, the sample is submitted for mass spectrometric analysis, resulting in peptide quantification and protein identification. While we will concentrate on cells in culture, we will point out procedures that can be used for labeling lysates generated from tissues, along with any minor modifications required for such samples. We will also outline, but not fully document, other strategies used in our lab to label proteins prior to mass spectrometric analysis, and describe under which conditions each procedure may be desirable. What is not covered in this chapter is anything but the most brief introduction to mass spectrometry (instrumentation, theory, etc.), nor do we attempt to cover much in the way of software used for post hoc analysis. These two topics are dependent upon one's resources, and where applicable, one's collaborators. We strongly encourage the reader to seek out expert advice on topics not covered here.
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Affiliation(s)
- Douglas E Vetter
- Department of Neurobiology and Anatomical Sciences, Univ. Mississippi Medical Center, 2500 N. State Street, Jackson, MS, 39216, USA.
| | - Johnvesly Basappa
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Tornari C, Towers ER, Gale JE, Dawson SJ. Regulation of the orphan nuclear receptor Nr2f2 by the DFNA15 deafness gene Pou4f3. PLoS One 2014; 9:e112247. [PMID: 25372459 PMCID: PMC4221282 DOI: 10.1371/journal.pone.0112247] [Citation(s) in RCA: 7] [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: 09/09/2014] [Accepted: 10/08/2014] [Indexed: 12/23/2022] Open
Abstract
Hair cells are the mechanotransducing cells of the inner ear that are essential for hearing and balance. POU4F3--a POU-domain transcription factor selectively expressed by these cells--has been shown to be essential for hair cell differentiation and survival in mice and its mutation in humans underlies late-onset progressive hearing loss (DFNA15). The downstream targets of POU4F3 are required for hair cell differentiation and survival. We aimed to identify such targets in order to elucidate the molecular pathways involved in hair cell production and maintenance. The orphan thyroid nuclear receptor Nr2f2 was identified as a POU4F3 target using a subtractive hybridization strategy and EMSA analysis showed that POU4F3 binds to two sites in the Nr2f2 5' flanking region. These sites were shown to be required for POU4F3 activation as their mutation leads to a reduction in the response of an Nr2f2 5' flanking region reporter construct to POU4F3. Immunocytochemistry was carried out in the developing and adult inner ear in order to investigate the relevance of this interaction in hearing. NR2F2 expression in the postnatal mouse organ of Corti was shown to be detectable in all sensory epithelia examined and characterised. These data demonstrate that Nr2f2 is a direct target of POU4F3 in vitro and that this regulatory relationship may be relevant to hair cell development and survival.
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Affiliation(s)
| | - Emily R. Towers
- UCL Ear Institute, University College London, London, United Kingdom
| | - Jonathan E. Gale
- UCL Ear Institute, University College London, London, United Kingdom
| | - Sally J. Dawson
- UCL Ear Institute, University College London, London, United Kingdom
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26
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Attenuation of noise-induced hearing loss using methylene blue. Cell Death Dis 2014; 5:e1200. [PMID: 24763057 PMCID: PMC4001318 DOI: 10.1038/cddis.2014.170] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 03/19/2014] [Accepted: 03/19/2014] [Indexed: 01/05/2023]
Abstract
The overproduction of reactive oxygen species (ROS) and reactive nitrogen species (RNS) has been known to contribute to the pathogenesis of noise-induced hearing loss. In this study, we discovered that in BALB/c mice pretreatment with methylene blue (MB) for 4 consecutive days significantly protected against cochlear injury by intense broad-band noise for 3 h. It decreased both compound threshold shift and permanent threshold shift and, further, reduced outer hair cell death in the cochlea. MB also reduced ROS and RNS formation after noise exposure. Furthermore, it protected against rotenone- and antimycin A-induced cell death and also reversed ATP generation in the in vitro UB-OC1 cell system. Likewise, MB effectively attenuated the noise-induced impairment of complex IV activity in the cochlea. In addition, it increased the neurotrophin-3 (NT-3) level, which could affect the synaptic connections between hair cells and spiral ganglion neurons in the noise-exposed cochlea, and also promoted the conservation of both efferent and afferent nerve terminals on the outer and inner hair cells. These findings suggest that the amelioration of impaired mitochondrial electron transport and the potentiation of NT-3 expression by treatment with MB have a significant therapeutic value in preventing ROS-mediated sensorineural hearing loss.
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Tropitzsch A, Arnold H, Bassiouni M, Müller A, Eckhard A, Müller M, Löwenheim H. Assessing cisplatin-induced ototoxicity and otoprotection in whole organ culture of the mouse inner ear in simulated microgravity. Toxicol Lett 2014; 227:203-12. [PMID: 24709139 DOI: 10.1016/j.toxlet.2014.03.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 03/25/2014] [Accepted: 03/27/2014] [Indexed: 12/20/2022]
Abstract
Cisplatin is a widely used anti-cancer drug. Ototoxicity is a major dose-limiting side-effect. A reproducible mammalian in-vitro model of cisplatin ototoxicity is required to screen and validate otoprotective drug candidates. We utilized a whole organ culture system of the postnatal mouse inner ear in a rotating wall vessel bioreactor under "simulated microgravity" culture conditions. As previously described this system allows whole organ culture of the inner ear and quantitative assessment of ototoxic effects of aminoglycoside induced hair cell loss. Here we demonstrate that this model is also applicable to the assessment of cisplatin induced ototoxicity. In this model cisplatin induced hair cell loss was dose and time dependent. Increasing exposure time of cisplatin led to decreasing EC50 concentrations. Outer hair cells were more susceptible than inner hair cells, and hair cells in the cochlear base were more susceptible than hair cells in the cochlear apex. Initial cisplatin dose determined the final extent of hair cell loss irrespective if the drug was withdrawn or continued. Dose dependant otoprotection was demonstrated by co-administration of the antioxidant agent N-acetyl l-cysteine. The results support the use of this inner ear organ culture system as an in vitro assay and validation platform for inner ear toxicology and the search for otoprotective compounds.
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Affiliation(s)
- Anke Tropitzsch
- University of Tübingen Medical School, Department of Otorhinolaryngology - Head & Neck Surgery, Hearing Research Center, Elfriede-Aulhorn-Straße 5, D-72076 Tübingen, Germany.
| | - Heinz Arnold
- University of Tübingen Medical School, Department of Otorhinolaryngology - Head & Neck Surgery, Hearing Research Center, Elfriede-Aulhorn-Straße 5, D-72076 Tübingen, Germany.
| | - Mohamed Bassiouni
- University of Tübingen Medical School, Department of Otorhinolaryngology - Head & Neck Surgery, Hearing Research Center, Elfriede-Aulhorn-Straße 5, D-72076 Tübingen, Germany.
| | - Andrea Müller
- University of Tübingen Medical School, Department of Otorhinolaryngology - Head & Neck Surgery, Hearing Research Center, Elfriede-Aulhorn-Straße 5, D-72076 Tübingen, Germany.
| | - Andreas Eckhard
- University of Tübingen Medical School, Department of Otorhinolaryngology - Head & Neck Surgery, Hearing Research Center, Elfriede-Aulhorn-Straße 5, D-72076 Tübingen, Germany.
| | - Marcus Müller
- University of Tübingen Medical School, Department of Otorhinolaryngology - Head & Neck Surgery, Hearing Research Center, Elfriede-Aulhorn-Straße 5, D-72076 Tübingen, Germany.
| | - Hubert Löwenheim
- University of Tübingen Medical School, Department of Otorhinolaryngology - Head & Neck Surgery, Hearing Research Center, Elfriede-Aulhorn-Straße 5, D-72076 Tübingen, Germany.
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Morlet T, Rabinowitz MR, Looney LR, Riegner T, Greenwood LA, Sherman EA, Achilly N, Zhu A, Yoo E, O'Reilly RC, Jinks RN, Puffenberger EG, Heaps A, Morton H, Strauss KA. A homozygous SLITRK6 nonsense mutation is associated with progressive auditory neuropathy in humans. Laryngoscope 2013; 124:E95-103. [PMID: 23946138 DOI: 10.1002/lary.24361] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 06/17/2013] [Accepted: 07/24/2013] [Indexed: 11/10/2022]
Abstract
OBJECTIVES/HYPOTHESIS SLITRK family proteins control neurite outgrowth and regulate synaptic development. In mice, Slitrk6 plays a role in the survival and innervation of sensory neurons in the inner ear, vestibular apparatus, and retina, and also influences axial eye length. We provide the first detailed description of the auditory phenotype in humans with recessive SLITRK6 deficiency. STUDY DESIGN Prospective observational case study. METHODS Nine closely related Amish subjects from an endogamous Amish community of Pennsylvania underwent audiologic and vestibular testing. Single nucleotide polymorphism microarrays were used to map the chromosome locus, and Sanger sequencing or high-resolution melt analysis were used to confirm the allelic variant. RESULTS All nine subjects were homozygous for a novel nonsense variant of SLITRK6 (c.1240C>T, p.Gln414Ter). Adult patients had high myopia. The 4 oldest SLITRK6 c.1240C>T homozygotes had absent ipsilateral middle ear muscle reflexes (MEMRs). Distortion product otoacoustic emissions (DPOAEs) were absent in all ears tested and the cochlear microphonic (CM) was increased in amplitude and duration in young patients and absent in the two oldest subjects. Auditory brainstem responses (ABRs) were dys-synchronised bilaterally with no reproducible waves I, III, or V at high intensities. Hearing loss and speech reception thresholds deteriorated symmetrically with age, which resulted in severe-to-profound hearing impairment by early adulthood. Vestibular evoked myogenic potentials were normal in three ears and absent in one. CONCLUSION Homozygous SLITRK6 c.1240C>T (p.Gln414Ter) nonsense mutations are associated with high myopia, cochlear dysfunction attributed to outer hair cell disease, and progressive auditory neuropathy.
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Affiliation(s)
- Thierry Morlet
- Auditory Physiology and Psychoacoustics Research Laboratory, duPont Hospital for Children, Wilmington, Delaware, U.S.A
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29
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A functional and genetic analysis of SOD2 promoter variants and their contribution to age-related hearing loss. Mech Ageing Dev 2013; 134:298-306. [DOI: 10.1016/j.mad.2013.02.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Revised: 02/11/2013] [Accepted: 02/26/2013] [Indexed: 11/18/2022]
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Regulated vesicular trafficking of specific PCDH15 and VLGR1 variants in auditory hair cells. J Neurosci 2013; 32:13841-59. [PMID: 23035094 DOI: 10.1523/jneurosci.1242-12.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Usher syndrome is a genetically heterogeneous disorder characterized by hearing and balance dysfunction and progressive retinitis pigmentosa. Mouse models carrying mutations for the nine Usher-associated genes have splayed stereocilia, and some show delayed maturation of ribbon synapses suggesting these proteins may play different roles in terminal differentiation of auditory hair cells. The presence of the Usher proteins at the basal and apical aspects of the neurosensory epithelia suggests the existence of regulated trafficking through specific transport proteins and routes. Immature mouse cochleae and UB/OC-1 cells were used in this work to address whether specific variants of PCDH15 and VLGR1 are being selectively transported to opposite poles of the hair cells. Confocal colocalization studies between apical and basal vesicular markers and the different PCDH15 and VLGR1 variants along with sucrose density gradients and the use of vesicle trafficking inhibitors show the existence of Usher protein complexes in at least two vesicular subpools. The apically trafficked pool colocalized with the early endosomal vesicle marker, rab5, while the basally trafficked pool associated with membrane microdomains and SNAP25. Moreover, coimmunoprecipitation experiments between SNAP25 and VLGR1 show a physical interaction of these two proteins in organ of Corti and brain. Collectively, these findings establish the existence of a differential vesicular trafficking mechanism for specific Usher protein variants in mouse cochlear hair cells, with the apical variants playing a potential role in endosomal recycling and stereocilia development/maintenance, and the basolateral variants involved in vesicle docking and/or fusion through SNAP25-mediated interactions.
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Park HY, Lee MH, Kang SU, Hwang HS, Park K, Choung YH, Kim CH. Nitric oxide mediates TNF-α-induced apoptosis in the auditory cell line. Laryngoscope 2012; 122:2256-64. [PMID: 22815072 DOI: 10.1002/lary.23444] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 03/30/2012] [Accepted: 04/26/2012] [Indexed: 12/15/2022]
Abstract
OBJECTIVES/HYPOTHESIS Tumor necrosis factor-alpha (TNF-α) is released in a variety of pathological states in the inner ear. Inducible nitric oxide synthase (iNOS) can be induced by cytokines and other inflammatory factors, and is generally thought to be associated with inflammation and other pathological processes in the cochlea. The purpose of the present study was to reveal that TNF-α could induce apoptosis in the auditory cell line and to investigate the role of nitric oxide (NO) in TNF-α-induced auditory cell death. STUDY DESIGN Experimental study. METHODS UB-OC1 cells and zebrafish were exposed to TNF-α. Flow cytometry, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) assay, assay of mitochondrial membrane potential (MMP), and electron microscopy were used to show that TNF-α could induce apoptosis. Western blot was used to measure iNOS expression and mitogen-activated protein kinase pathway. RESULTS Flow cytometric analysis, TUNEL assay, MMP, and electron microscopy all demonstrated that TNF-α could induce apoptosis in UB-OC1 cells. TNF-α significantly increased NO generation and iNOS expression. Pretreatment with iNOS blocker NG-methyl-L-arginine (NMA) attenuated TNF-α-induced cell death and caspase-3 activation. Also, TNF-α treatment increased p-p38 and p-ERK, and pretreatment of NMA reduced this increased expression of p-p38 and p-ERK. CONCLUSIONS TNF-α can induce apoptosis in the auditory cell line, and NO production in response to TNF-α is essential for apoptosis.
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Affiliation(s)
- Hun Yi Park
- Department of OtolaryngologyAjou University School of Medicine, Suwon, South Korea
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32
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Brunetta I, Casalotti SO, Hart IR, Forge A, Reynolds LE. β3-integrin is required for differentiation in OC-2 cells derived from mammalian embryonic inner ear. BMC Cell Biol 2012; 13:5. [PMID: 22424110 PMCID: PMC3329412 DOI: 10.1186/1471-2121-13-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 03/17/2012] [Indexed: 11/21/2022] Open
Abstract
Background The mammalian inner ear contains the organ of Corti which is responsible for the conversion of sound into neuronal signals. This specialised epithelial tissue is the product of a complex developmental process where a common precursor cell type differentiates into the sound transducing hair cells and the non-innervated supporting cells. We hypothesised that integrin proteins, which are involved in cell attachment to extracellular matrix proteins and cellular signalling, play a role in the differentiation process of the precursor inner ear epithelial cells. To test our hypothesis we have utilised a cell line (OC-2) derived from E13 embryonic immortomouse inner ears. In vitro, by switching the incubation temperature from 33°C to 39°C, the OC-2 cells can be induced to differentiate and express hair cells markers, such as Myosin VIIa. The OC-2 cells are thus a useful model system for testing mechanism of hair cells differentiation. Results We have identified 4 integrin subunits which are expressed in OC-2 cells: α6, αv, β1 and β3. Among these, the relative level of expression of the αv, β1 and β3 subunits increased in a time dependent manner when the cells were exposed to the differentiating temperature of 39°C, most notably so for β3 which was not detectable at 33°C. Treatment of fully differentiated OC-2 cells with siRNA against the four integrin subunits reduced the expression of not only the respective integrin proteins but also of the hair cell marker Myosin VIIa. Conversely over-expression of β3 was sufficient to induce the expression of Myosin VIIa at 33°C. Conclusions Our data demonstrate that modulation of integrin expression is associated with the differentiation process of the OC-2 cells. This suggests that the maturation of the organ of Corti, from where OC-2 cells are derived, may also depend on changes of gene expression associated with integrin expression.
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Affiliation(s)
- Ivan Brunetta
- Centre for Auditory Research, UCL Ear Institute, University College London, London WC1X 8EE, UK
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33
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Zallocchi M, Meehan DT, Delimont D, Rutledge J, Gratton MA, Flannery J, Cosgrove D. Role for a novel Usher protein complex in hair cell synaptic maturation. PLoS One 2012; 7:e30573. [PMID: 22363448 PMCID: PMC3281840 DOI: 10.1371/journal.pone.0030573] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 12/22/2011] [Indexed: 12/22/2022] Open
Abstract
The molecular mechanisms underlying hair cell synaptic maturation are not well understood. Cadherin-23 (CDH23), protocadherin-15 (PCDH15) and the very large G-protein coupled receptor 1 (VLGR1) have been implicated in the development of cochlear hair cell stereocilia, while clarin-1 has been suggested to also play a role in synaptogenesis. Mutations in CDH23, PCDH15, VLGR1 and clarin-1 cause Usher syndrome, characterized by congenital deafness, vestibular dysfunction and retinitis pigmentosa. Here we show developmental expression of these Usher proteins in afferent spiral ganglion neurons and hair cell synapses. We identify a novel synaptic Usher complex comprised of clarin-1 and specific isoforms of CDH23, PCDH15 and VLGR1. To establish the in vivo relevance of this complex, we performed morphological and quantitative analysis of the neuronal fibers and their synapses in the Clrn1−/− mouse, which was generated by incomplete deletion of the gene. These mice showed a delay in neuronal/synaptic maturation by both immunostaining and electron microscopy. Analysis of the ribbon synapses in Ames waltzerav3J mice also suggests a delay in hair cell synaptogenesis. Collectively, these results show that, in addition to the well documented role for Usher proteins in stereocilia development, Usher protein complexes comprised of specific protein isoforms likely function in synaptic maturation as well.
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Affiliation(s)
- Marisa Zallocchi
- Boys Town National Research Hospital, Omaha, Nebraska, United States of America
| | - Daniel T. Meehan
- Boys Town National Research Hospital, Omaha, Nebraska, United States of America
| | - Duane Delimont
- Boys Town National Research Hospital, Omaha, Nebraska, United States of America
| | - Joseph Rutledge
- Otolaryngology-Head, Neck Surgery, St Louis University, St Louis, Missouri, United States of America
| | - Michael Anne Gratton
- Otolaryngology-Head, Neck Surgery, St Louis University, St Louis, Missouri, United States of America
| | - John Flannery
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, United States of America
| | - Dominic Cosgrove
- Boys Town National Research Hospital, Omaha, Nebraska, United States of America
- University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- * E-mail:
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Zallocchi M, Meehan DT, Delimont D, Rutledge J, Gratton MA, Flannery J, Cosgrove D. Role for a novel Usher protein complex in hair cell synaptic maturation. PLoS One 2012; 7:e30573. [PMID: 22363448 DOI: 10.1371/journal.pone.0030573pone-d-11-06651[pii]] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 12/22/2011] [Indexed: 05/19/2023] Open
Abstract
The molecular mechanisms underlying hair cell synaptic maturation are not well understood. Cadherin-23 (CDH23), protocadherin-15 (PCDH15) and the very large G-protein coupled receptor 1 (VLGR1) have been implicated in the development of cochlear hair cell stereocilia, while clarin-1 has been suggested to also play a role in synaptogenesis. Mutations in CDH23, PCDH15, VLGR1 and clarin-1 cause Usher syndrome, characterized by congenital deafness, vestibular dysfunction and retinitis pigmentosa. Here we show developmental expression of these Usher proteins in afferent spiral ganglion neurons and hair cell synapses. We identify a novel synaptic Usher complex comprised of clarin-1 and specific isoforms of CDH23, PCDH15 and VLGR1. To establish the in vivo relevance of this complex, we performed morphological and quantitative analysis of the neuronal fibers and their synapses in the Clrn1-/- mouse, which was generated by incomplete deletion of the gene. These mice showed a delay in neuronal/synaptic maturation by both immunostaining and electron microscopy. Analysis of the ribbon synapses in Ames waltzer(av3J) mice also suggests a delay in hair cell synaptogenesis. Collectively, these results show that, in addition to the well documented role for Usher proteins in stereocilia development, Usher protein complexes comprised of specific protein isoforms likely function in synaptic maturation as well.
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Affiliation(s)
- Marisa Zallocchi
- Boys Town National Research Hospital, Omaha, Nebraska, United States of America
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Abstract
PURPOSE OF REVIEW In evaluating strategies to preserve or regenerate the cochlea, understanding the process of labyrinthine injury on a cellular and molecular level is crucial. Examination of inner ear injury reveals mechanism-specific types of damage, often at specific areas within the cochlea. Site-specific interventions can then be considered. RECENT FINDINGS The review will briefly summarize the historical perspective of advancements in hearing science through 2006. Areas of research covered include hair cell protection, hair cell regeneration, spiral ganglion cell regeneration, and stria vascularis metabolic regulation. SUMMARY The review will briefly summarize the early development of a few such site-specific interventions for inner ear functional rehabilitation, for work done prior to 2006. The outstanding reviews of cutting edge research from this year's and last year's Hearing Science section of Current Opinion in Otolaryngology - Head and Neck Surgery can then be understood and appreciated in a more informed manner.
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Milo M, Cacciabue-Rivolta D, Kneebone A, Van Doorninck H, Johnson C, Lawoko-Kerali G, Niranjan M, Rivolta M, Holley M. Genomic analysis of the function of the transcription factor gata3 during development of the mammalian inner ear. PLoS One 2009; 4:e7144. [PMID: 19774072 PMCID: PMC2742898 DOI: 10.1371/journal.pone.0007144] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Accepted: 08/17/2009] [Indexed: 11/25/2022] Open
Abstract
We have studied the function of the zinc finger transcription factor gata3 in auditory system development by analysing temporal profiles of gene expression during differentiation of conditionally immortal cell lines derived to model specific auditory cell types and developmental stages. We tested and applied a novel probabilistic method called the gamma Model for Oligonucleotide Signals to analyse hybridization signals from Affymetrix oligonucleotide arrays. Expression levels estimated by this method correlated closely (p<0.0001) across a 10-fold range with those measured by quantitative RT-PCR for a sample of 61 different genes. In an unbiased list of 26 genes whose temporal profiles clustered most closely with that of gata3 in all cell lines, 10 were linked to Insulin-like Growth Factor signalling, including the serine/threonine kinase Akt/PKB. Knock-down of gata3 in vitro was associated with a decrease in expression of genes linked to IGF-signalling, including IGF1, IGF2 and several IGF-binding proteins. It also led to a small decrease in protein levels of the serine-threonine kinase Akt2/PKBbeta, a dramatic increase in Akt1/PKBalpha protein and relocation of Akt1/PKBalpha from the nucleus to the cytoplasm. The cyclin-dependent kinase inhibitor p27(kip1), a known target of PKB/Akt, simultaneously decreased. In heterozygous gata3 null mice the expression of gata3 correlated with high levels of activated Akt/PKB. This functional relationship could explain the diverse function of gata3 during development, the hearing loss associated with gata3 heterozygous null mice and the broader symptoms of human patients with Hearing-Deafness-Renal anomaly syndrome.
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Affiliation(s)
- Marta Milo
- NIHR Cardiovascular Biomedical Research Unit, Sheffield Teaching Hospitals NHS Trust, Sheffield, United Kingdom
| | | | - Adam Kneebone
- Department of Biomedical Science, Addison Building, Western Bank, Sheffield, United Kingdom
| | - Hikke Van Doorninck
- Department of Neurosciences, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Claire Johnson
- Pfizer Global Research UK, Sandwich, Kent, United Kingdom
| | - Grace Lawoko-Kerali
- Department of Biomedical Science, Addison Building, Western Bank, Sheffield, United Kingdom
| | - Mahesan Niranjan
- Department of Electronics and Computer Science, University of Southampton, Southampton, United Kingdom
| | - Marcelo Rivolta
- Department of Biomedical Science, Addison Building, Western Bank, Sheffield, United Kingdom
| | - Matthew Holley
- Department of Biomedical Science, Addison Building, Western Bank, Sheffield, United Kingdom
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Zallocchi M, Meehan DT, Delimont D, Askew C, Garige S, Gratton MA, Rothermund-Franklin CA, Cosgrove D. Localization and expression of clarin-1, the Clrn1 gene product, in auditory hair cells and photoreceptors. Hear Res 2009; 255:109-20. [PMID: 19539019 DOI: 10.1016/j.heares.2009.06.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Revised: 05/19/2009] [Accepted: 06/10/2009] [Indexed: 01/13/2023]
Abstract
The Usher syndrome 3A (CLRN1) gene encodes clarin-1, which is a member of the tetraspanin family of transmembrane proteins. Although identified more than 6 years ago, little is known about its localization or function in the eye and ear. We developed a polyclonal antibody that react with all clarin-1 isoforms and used it to characterize protein expression in cochlea and retina. In the cochlea, we observe clarin-1expression in the stereocilia of P0 mice, and in synaptic terminals present at the base of the auditory hair cells from E18 to P6. In the retina, clarin-1 localizes to the connecting cilia, inner segment of photoreceptors and to the ribbon synapses. RT-PCR from P0 cochlea and P28 retina show mRNAs encoding only isoforms 2 and 3. Western blots show that only isoform 2 is present in protein extracts from these same tissues. We examined clarin-1 expression in the immortomouse-derived hair cell line UB/OC-1. Only isoform 2 is expressed in UB/OC-1 at both mRNA and protein levels, suggesting this isoform is biologically relevant to hair cell function. The protein co-localizes with microtubules and post-transgolgi vesicles. The subcellular localization of clarin-1 in hair cells and photoreceptors suggests it functions at both the basal and apical poles of neurosensoriepithelia.
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Short interfering RNA against transient receptor potential vanilloid 1 attenuates cisplatin-induced hearing loss in the rat. J Neurosci 2009; 28:13056-65. [PMID: 19052196 DOI: 10.1523/jneurosci.1307-08.2008] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Cisplatin, a chemotherapeutic agent of choice for the treatment of solid tumors, produces hearing loss in approximately half a million new cancer patients annually in the United States. The hearing loss is due, in part, to increased generation of reactive oxygen species (ROS) in the cochlea, leading to lipid peroxidation and damage or death of outer hair cells in the organ of Corti. The cochlea expresses the transient receptor potential vanilloid 1 (TRPV1), which are normally expressed on small diameter neurons in the peripheral nervous system and mediate thermal sensitivity, but whose role in the cochlea is unclear. In this study, we show that TRPV1 is coregulated along with the NADPH oxidase isoform, NOX3, by cisplatin. Induction of these proteins by cisplatin is dependent on ROS generation, since it is reversed by systemic lipoic acid administration. In organ of Corti hair cell cultures (UB/OC-1 cells), cisplatin activates and induces TRPV1 and NOX3, leading to apoptosis of these cells. Inhibition of TRPV1 by capsazepine or ruthenium red reduced the apoptosis, implicating TRPV1 in this process. Treatment of UB/OC-1 cultures with short interfering RNA (siRNA) against either TRPV1 or NOX3 reduced cisplatin-induced apoptosis, while round window application of TRPV1 siRNA to rats reduced TRPV1 expression, decreased damage to outer hair cells and reduced cisplatin-induced hearing loss. These data provide a link between NOX3 and TRPV1 in cisplatin-induced hearing loss and suggest that targeting these proteins for knockdown by siRNA could serve as a novel approach in treating cisplatin ototoxicity.
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40
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Multiplexed isobaric tagging protocols for quantitative mass spectrometry approaches to auditory research. Methods Mol Biol 2009; 493:345-66. [PMID: 18839358 DOI: 10.1007/978-1-59745-523-7_21] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Modern biologists have at their disposal a large array of techniques used to assess the existence and relative or absolute quantity of any molecule of interest in a sample. However, implementing most of these procedures can be a daunting task for the first time, even in a lab with experienced researchers. Just choosing a protocol to follow can take weeks while all of the nuances are examined and it is determined whether a protocol will (a) give the desired results, (b) result in interpretable and unbiased data, and (c) be amenable to the sample of interest. We detail here a robust procedure for labeling proteins in a complex lysate for the ultimate differential quantification of protein abundance following experimental manipulations. Following a successful outcome of the labeling procedure, the sample is submitted for mass spectrometric analysis, resulting in peptide quantification and protein identification. While we will concentrate on cells in culture, we will point out procedures that can be used for labeling lysates generated from other tissues, along with any minor modifications required for such samples. We will also outline, but not fully document, other strategies used in our lab to label proteins prior to mass spectrometric analysis, and describe under which conditions each procedure may be desirable. What is not covered in this chapter is anything but the most brief introduction to mass spectrometry (instrumentation, theory, etc.), nor do we attempt to cover much in the way of software used for post hoc analysis. These two topics are dependant upon one's resources, and where applicable, one's collaborators. We strongly encourage the reader to seek out expert advice on topics not covered here.
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Chiu LL, Cunningham LL, Raible DW, Rubel EW, Ou HC. Using the zebrafish lateral line to screen for ototoxicity. J Assoc Res Otolaryngol 2008; 9:178-90. [PMID: 18408970 DOI: 10.1007/s10162-008-0118-y] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2008] [Accepted: 03/05/2008] [Indexed: 10/22/2022] Open
Abstract
The zebrafish is a valuable model for studying hair cell development, structure, genetics, and behavior. Zebrafish and other aquatic vertebrates have hair cells on their body surface organized into a sensory system called the lateral line. These hair cells are highly accessible and easily visualized using fluorescent dyes. Morphological and functional similarities to mammalian hair cells of the inner ear make the zebrafish a powerful preparation for studying hair cell toxicity. The ototoxic potential of drugs has historically been uncovered by anecdotal reports that have led to more formal investigation. Currently, no standard screen for ototoxicity exists in drug development. Thus, for the vast majority of Food and Drug Association (FDA)-approved drugs, the ototoxic potential remains unknown. In this study, we used 5-day-old zebrafish larvae to screen a library of 1,040 FDA-approved drugs and bioactives (NINDS Custom Collection II) for ototoxic effects in hair cells of the lateral line. Hair cell nuclei were selectively labeled using a fluorescent vital dye. For the initial screen, fish were exposed to drugs from the library at a 100-muM concentration for 1 h in 96-well tissue culture plates. Hair cell viability was assessed in vivo using fluorescence microscopy. One thousand forty drugs were rapidly screened for ototoxic effects. Seven known ototoxic drugs included in the library, including neomycin and cisplatin, were positively identified using these methods, as proof of concept. Fourteen compounds without previously known ototoxicity were discovered to be selectively toxic to hair cells. Dose-response curves for all 21 ototoxic compounds were determined by quantifying hair cell survival as a function of drug concentration. Dose-response relationships in the mammalian inner ear for two of the compounds without known ototoxicity, pentamidine isethionate and propantheline bromide, were then examined using in vitro preparations of the adult mouse utricle. Significant dose-dependent hair cell loss in the mouse utricle was demonstrated for both compounds. This study represents an important step in validating the use of the zebrafish lateral line as a screening tool for the identification of potentially ototoxic drugs.
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Affiliation(s)
- Lynn L Chiu
- Department of Otolaryngology-Head and Neck Surgery, University of Washington, Box 356515, Seattle, WA 98195, USA
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42
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Whole organ culture of the postnatal sensory inner ear in simulated microgravity. J Neurosci Methods 2008; 171:60-71. [PMID: 18440073 DOI: 10.1016/j.jneumeth.2008.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 01/16/2008] [Accepted: 02/04/2008] [Indexed: 11/23/2022]
Abstract
Among the three major biological in vitro models, cell culture, tissue culture, and organ culture, the latter provides the closest approximation to the in vivo situation, but also requires the most demanding culture conditions. Due to its small size and complex tissue architecture, the mammalian inner ear provides a particular challenge to the development of whole organ culture. Using a rotating bioreactor system with simulated microgravity conditions, the entire mouse inner ear organ can be maintained in culture for up to seven days with preservation of sensory organ morphology and robust marker protein expression in sensory hair cells. Controlled sensory cell lesions can be induced by the ototoxic agent, neomycin sulphate, as a toxicologic model of hair cell degeneration and hair cell loss. The results demonstrate that simulated microgravity organ culture of the inner ear affords an in vitro model for the investigation of developmental, regulatory, and differentiation processes, as well as toxicological, biotechnological, and pharmaceutical screening applications within the normal and pathologic sensory hearing organ.
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Chen W, Cacciabue-Rivolta DI, Moore HD, Rivolta MN. The human fetal cochlea can be a source for auditory progenitors/stem cells isolation. Hear Res 2007; 233:23-9. [PMID: 17646067 DOI: 10.1016/j.heares.2007.06.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2007] [Revised: 05/22/2007] [Accepted: 06/06/2007] [Indexed: 12/29/2022]
Abstract
The development of new stem cell-based technologies is creating new hopes in regenerative medicine. Hearing-impaired individuals should benefit greatly from the development of a cell-based regenerative strategy to treat deafness. An important achievement would be to develop a human-based system that could bring the advances made in animal models closer to clinical application. In this work, we have explored the suitability of the developing fetal cochlea to be used as a source for the extraction of auditory progenitor/stem cells. We have established cultures that express critical markers such as NESTIN, SOX2, GATA3 and PAX2. These cultures can be expanded in vitro for several months and differentiating markers such as ATOH1/HATH1 and POU4F3/BRN3C can be induced by manipulating the culture conditions using specific growth factors such as bFGF, EGF and retinoic acid.
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Affiliation(s)
- Wei Chen
- Centre for Stem Cell Biology, Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TN, UK
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Parker MA, Corliss DA, Gray B, Anderson JK, Bobbin RP, Snyder EY, Cotanche DA. Neural stem cells injected into the sound-damaged cochlea migrate throughout the cochlea and express markers of hair cells, supporting cells, and spiral ganglion cells. Hear Res 2007; 232:29-43. [PMID: 17659854 PMCID: PMC2032013 DOI: 10.1016/j.heares.2007.06.007] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2007] [Revised: 06/06/2007] [Accepted: 06/08/2007] [Indexed: 11/27/2022]
Abstract
Most cases of hearing loss are caused by the death or dysfunction of one of the many cochlear cell types. We examined whether cells from a neural stem cell line could replace cochlear cell types lost after exposure to intense noise. For this purpose, we transplanted a clonal stem cell line into the scala tympani of sound damaged mice and guinea pigs. Utilizing morphological, protein expression and genetic criteria, stem cells were found with characteristics of both neural tissues (satellite, spiral ganglion, and Schwann cells) and cells of the organ of Corti (hair cells, supporting cells). Additionally, noise-exposed, stem cell-injected animals exhibited a small but significant increase in the number of satellite cells and Type I spiral ganglion neurons compared to non-injected noise-exposed animals. These results indicate that cells of this neural stem cell line migrate from the scala tympani to Rosenthal's canal and the organ of Corti. Moreover, they suggest that cells of this neural stem cell line may derive some information needed from the microenvironment of the cochlea to differentiate into replacement cells in the cochlea.
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Affiliation(s)
- Mark A Parker
- Department of Communication Sciences and Disorders, Emerson College, Boston, MA 02114, USA.
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45
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Nolan LS, Jagutpal SS, Cadge BA, Woo P, Dawson SJ. Identification and functional analysis of common sequence variants in the DFNA15 gene, Brn-3c. Gene 2007; 400:89-97. [PMID: 17611044 DOI: 10.1016/j.gene.2007.05.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2006] [Revised: 03/29/2007] [Accepted: 05/31/2007] [Indexed: 10/23/2022]
Abstract
A rare mutation in Brn-3c (Brn3.1, POU4F3) underlies adult onset hearing loss (DFNA15) and targeted deletion of this gene in mice leads to complete deafness due to loss of sensory hair cells from the cochlea. Therefore the aim of our study was to identify and characterise common functional variation in the Brn-3c gene, which could potentially be a genetic risk for more common forms of adult onset hearing loss. We identified seven sequence variants at the Brn-3c locus. One of these, a novel, common variant at position -3432 was extremely complex consisting of a variable guanine repeat that also exhibited single nucleotide substitutions within the poly-guanine repeat: -3432 poly-G polymorphism. In-vitro studies show that this polymorphism modifies binding affinity for the SP1 transcription factor. Furthermore, reporter constructs of the Brn-3c 5'-flanking region containing different -3432 poly-G alleles show altered transcriptional activity when endogenous SP1 levels are reduced using a dominant negative approach. Results also indicate that this effect is influenced by the length of a novel polymorphic (GT)(n) repeat at position -566 in the Brn-3c 5'-flanking region. In summary, our data show there are common sequence variants in the Brn-3c 5'-flanking region that affect transcriptional regulation in vitro; these variants are candidates for large-scale population based association analysis as they could potentially affect the genetic risk for more common types of adult onset hearing loss.
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Affiliation(s)
- Lisa S Nolan
- Centre for Auditory Research, Ear Institute, University College London, 332 Gray's Inn Road, London, WC1X 8EE, United Kingdom
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Choi BM, Kim SM, Park TK, Li G, Hong SJ, Park R, Chung HT, Kim BR. Piperine protects cisplatin-induced apoptosis via heme oxygenase-1 induction in auditory cells. J Nutr Biochem 2007; 18:615-22. [PMID: 17418561 DOI: 10.1016/j.jnutbio.2006.11.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Revised: 10/11/2006] [Accepted: 11/01/2006] [Indexed: 01/23/2023]
Abstract
Piperine is a major component of black pepper, Piper nigrum Linn, used widely in traditional medicine. In this study, we examined whether piperine could protect House Ear Institute-Organ of Corti 1 (HEI-OC1) cells against cisplatin-induced apoptosis through the induction of heme oxygenase (HO)-1 expression. Piperine (10-100 microM) induced the expression of HO-1 in dose- and time-dependent manners. Piperine also induced antioxidant response element-luciferase and translocated nuclear factor-E2-related factor-2 (Nrf2) to nucleus. Piperine activated the c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase and p38 mitogen-activated protein kinase (MAPK) pathways, and the JNK pathway played an important role in piperine-induced HO-1 expression. Piperine protected the cells against cisplatin-induced apoptosis. The protective effect of piperine was abrogated by zinc protoporphyrin IX, an HO inhibitor, and antisense oligodeoxynucleotides against HO-1 gene. These results demonstrate that the expression of HO-1 by piperine is mediated by both JNK pathway and Nrf2, and the expression inhibits cisplatin-induced apoptosis in HEI-OC1 cells.
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Affiliation(s)
- Byung-Min Choi
- Department of Biochemistry, School of Medicine, Wonkwang University, Iksan, Chonbuk 570-749, Republic of Korea
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47
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Choi BM, Lee JA, Gao SS, Eun SY, Kim YS, Ryu SY, Choi YH, Park R, Kwon DY, Kim BR. Brazilin and the extract from Caesalpinia sappan L. protect oxidative injury through the expression of heme oxygenase-1. Biofactors 2007; 30:149-57. [PMID: 18525109 DOI: 10.1002/biof.5520300302] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In this study, we examined the protective effects of Caesalpinia sappan L. and its major component, brazilin, against tert-butylhydroperoxide (t-BHP)-induced cell death in House Ear Institute-Organ of Corti 1 (HEI-OC1) cells. We found that the extract of C. sappan L. and brazilin induced antioxidant response element (ARE)-luciferase activity and heme oxygenase-1 (HO-1) expression in a concentration-dependent manner. The inductive effect of brazilin was more potent than the extract of C. sappan L. and the expression of HO-1 reached a peak at 12 h after brazilin treatment. The extract and brazilin protected the cells against t-BHP-induced cell death. Their protective effects were abrogated by zinc protoporphyrin IX (ZnPP IX), a HO inhibitor. These results demonstrate that the extract of C. sappan L. and brazilin induce the expression of HO-1 and the enzyme diminishes t-BHP-induced cell death in HEI-OC1 cells.
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Affiliation(s)
- Byung-Min Choi
- Vestibulocochlear Research Center and Department of Biochemistry, School of Medicine, Wonkwang University, Chonbuk, Republic of Korea
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Holley MC, Kneebone A, Milo M. Information for gene networks in inner ear development: a study centered on the transcription factor gata2. Hear Res 2006; 227:32-40. [PMID: 16797894 DOI: 10.1016/j.heares.2006.04.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Revised: 04/12/2006] [Accepted: 04/27/2006] [Indexed: 01/15/2023]
Abstract
The search for molecular mechanisms to stimulate sensory regeneration in the mammalian inner ear is commonly based upon developmental studies. This has revealed many genes that regulate the differentiation of sensory cells. A major challenge is to place these genes into the context of functional networks that describe developmental processes more fully and increase the chances of identifying useful therapeutic targets. We used a novel approach to identify genes that are functionally related to the transcription factor gata2. Temporal profiles of gene expression were derived from three conditionally immortal cell lines and clustered to those of gata2 by applying the gamma model for oligonucleotide signals, a statistical method that allows quantitative analysis of oligonucleotide array data. We derived an objective list of 28 genes that clustered with gata2 in all three cell lines. A number of these genes have known functional links with gata2. Genes encoding CCAAT/enhancer binding proteins (C/EBP) and signal transducer and activation of transcription 3 (Stat3) are especially interesting as they are known to bind gata proteins directly. The results provide strong evidence that our experimental approach can reveal functional relationships between genes that regulate fundamental processes in the differentiation of sensory cells in the inner ear.
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Affiliation(s)
- M C Holley
- Department of Biomedical Science, University of Sheffield, Addison Building, Western Bank, Sheffield S10 2TN, UK.
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49
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Manji SSM, Sørensen BS, Klockars T, Lam T, Hutchison W, Dahl HHM. Molecular characterization and expression of maternally expressed gene 3 (Meg3/Gtl2) RNA in the mouse inner ear. J Neurosci Res 2006; 83:181-90. [PMID: 16342203 DOI: 10.1002/jnr.20721] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The pathways responsible for sound perception in the cochlea involve the coordinated and regulated expression of hundreds of genes. By using microarray analysis, we identified several transcripts enriched in the inner ear, including the maternally expressed gene 3 (Meg3/Gtl2), an imprinted noncoding RNA. Real-time PCR analysis demonstrated that Meg3/Gtl2 was highly expressed in the cochlea, brain, and eye. Molecular studies revealed the presence of several Meg3/Gtl2 RNA splice variants in the mouse cochlea, brain, and eye. In situ hybridizations showed intense Meg3/Gtl2 RNA staining in the nuclei of type I spiral ganglion cells and in cerebellum near the dorsal vestibular region of the cochlea. In embryonic mouse head sections, Meg3/Gtl2 RNA expression was observed in the otocyst, brain, eye, cartilage, connective tissue, and muscle. Meg3/Gtl2 RNA expression increased in the developing otocyst and localized to the spiral ganglion, stria vascularis, Reissner's membrane, and greater epithelial ridge (GER) in the cochlear duct. RT-PCR analysis performed on cell lines derived from the organ of Corti, representing neural, supporting, and hair cells, showed significantly elevated levels of Meg3/Gtl2 expression in differentiated neural cells. We propose that Meg3/Gtl2 RNA functions as a noncoding regulatory RNA in the inner ear and that it plays a role in pattern specification and differentiation of cells during otocyst development, as well as in the maintenance of a number of terminally differentiated cochlear cell types.
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Affiliation(s)
- Shehnaaz S M Manji
- Gene Identification and Expression, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia.
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50
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Kim HJ, So HS, Lee JH, Lee JH, Park C, Park SY, Kim YH, Youn MJ, Kim SJ, Chung SY, Lee KM, Park R. Heme oxygenase-1 attenuates the cisplatin-induced apoptosis of auditory cells via down-regulation of reactive oxygen species generation. Free Radic Biol Med 2006; 40:1810-9. [PMID: 16678019 DOI: 10.1016/j.freeradbiomed.2006.01.018] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Revised: 01/10/2006] [Accepted: 01/13/2006] [Indexed: 10/25/2022]
Abstract
Heme oxygenase-1 (HO-1), the rate-limiting enzyme of heme catabolism, is known to modulate various cellular functions, including cytokine production, cell proliferation, and apoptosis, in stress-related conditions. However, the role of HO-1 in the auditory system remains elusive. Herein, we demonstrate that pharmacologic induction of HO-1 along with catalytic activation significantly suppressed apoptosis of HEI-OC1 cells induced by cisplatin. Studies of ectopic expression of pcDNA3-HO-1 and siRNA of HO-1 further revealed the protective role of HO-1 against cisplatin in HEI-OC1 cells. Among the catabolic metabolites of HO-1, both carbon monoxide (CO) and bilirubin were directly involved in the protective role of HO-1 against cisplatin through inhibition of reactive oxygen species generation. Furthermore, pharmacological induction of HO-1 completely prevented the destruction of outer hair cell arrays by cisplatin through a CO-dependent mechanism in organotrophic culture of the rat primary organ of Corti explants. These results suggest that HO-1 may serve as a safeguard of auditory sensory hair cells against a variety of challenges of oxidative stress, including noise trauma, presbycusis, and ototoxic drugs, respectively.
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Affiliation(s)
- Hyung-Jin Kim
- Vestibulocochlear Research Center (VCRC) and Department of Microbiology, Wonkwang University School of Medicine, 344-2 Shinyong-dong Iksan, Jeonbuk 570-749, South Korea
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