1
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Zhao Y, Huang S, Xie R, Liu J. Extracellular ATP accelerates cell death and decreases tight junction protein ZO-1 in hypoxic cochlear strial marginal cells in neonatal rats. Cell Signal 2023:110732. [PMID: 37245680 DOI: 10.1016/j.cellsig.2023.110732] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 05/17/2023] [Accepted: 05/23/2023] [Indexed: 05/30/2023]
Abstract
In the cochlear, extracellular ATP (eATP) plays an important role in both physiological and pathological processes, but its role in the hypoxic cochlear remains unclear. The present study aims to investigate the relationship between eATP and hypoxic marginal cells (MCs) in the stria vascularis in cochlear. Combining various methodologies, we found that eATP accelerates cell death and decreases tight junction protein zonula occludens-1 (ZO-1) in hypoxic MCs. Flow cytometry and western blot analyses revealed an increase in apoptosis levels and suppression of autophagy, indicating that eATP causes additional cell death by increasing the apoptosis of hypoxic MCs. Given that autophagy inhibits apoptosis to protect MCs under hypoxia, apoptosis is probably enchanced by suppressing autophagy. Interleukin-33(IL-33)/suppression of tumorigenicity-2(ST-2)/matrix metalloprotein 9(MMP9) pathway activation was also observed during the process. Further experiments involving the use of additional IL-33 protein and an MMP9 inhibitor indicated that this pathway is responsible for the damage to the ZO-1 protein in hypoxic MCs. Our study revealed the adverse effect of eATP on the survival and ZO-1 protein expression of hypoxic MCs, as well as the underlying mechanism.
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Affiliation(s)
- Yanyun Zhao
- Department of Otorhinolaryngology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Sihan Huang
- Department of Otorhinolaryngology, Zhangzhou Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Renwei Xie
- Department of Otorhinolaryngology, Renhe Hospital, Baoshan District, Shanghai, China
| | - Jun Liu
- Department of Otorhinolaryngology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China.
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2
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Al Aameri RFH, Alanisi EMA, Oluwatosin A, Al Sallami D, Sheth S, Alberts I, Patel S, Rybak LP, Ramkumar V. Targeting CXCL1 chemokine signaling for treating cisplatin ototoxicity. Front Immunol 2023; 14:1125948. [PMID: 37063917 PMCID: PMC10102581 DOI: 10.3389/fimmu.2023.1125948] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Accepted: 03/17/2023] [Indexed: 04/03/2023] Open
Abstract
Cisplatin is chemotherapy used for solid tumor treatment like lung, bladder, head and neck, ovarian and testicular cancers. However, cisplatin-induced ototoxicity limits the utility of this agent in cancer patients, especially when dose escalations are needed. Ototoxicity is associated with cochlear cell death through DNA damage, the generation of reactive oxygen species (ROS) and the consequent activation of caspase, glutamate excitotoxicity, inflammation, apoptosis and/or necrosis. Previous studies have demonstrated a role of CXC chemokines in cisplatin ototoxicity. In this study, we investigated the role of CXCL1, a cytokine which increased in the serum and cochlea by 24 h following cisplatin administration. Adult male Wistar rats treated with cisplatin demonstrated significant hearing loss, assessed by auditory brainstem responses (ABRs), hair cell loss and loss of ribbon synapse. Immunohistochemical studies evaluated the levels of CXCL1 along with increased presence of CD68 and CD45-positive immune cells in cochlea. Increases in CXCL1 was time-dependent in the spiral ganglion neurons and organ of Corti and was associated with progressive increases in CD45, CD68 and IBA1-positive immune cells. Trans-tympanic administration of SB225002, a chemical inhibitor of CXCR2 (receptor target for CXCL1) reduced immune cell migration, protected against cisplatin-induced hearing loss and preserved hair cell integrity. We show that SB225002 reduced the expression of CXCL1, NOX3, iNOS, TNF-α, IL-6 and COX-2. Similarly, knockdown of CXCR2 by trans-tympanic administration of CXCR2 siRNA protected against hearing loss and loss of outer hair cells and reduced ribbon synapses. In addition, SB225002 reduced the expression of inflammatory mediators induced by cisplatin. These results implicate the CXCL1 chemokine as an early player in cisplatin ototoxicity, possibly by initiating the immune cascade, and indicate that CXCR2 is a relevant target for treating cisplatin ototoxicity.
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Affiliation(s)
- Raheem F. H. Al Aameri
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Entkhab M. A. Alanisi
- Department of Pharmaceutical Sciences, Larkin University College of Pharmacy, Miami, FL, United States
| | - Adu Oluwatosin
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Dheyaa Al Sallami
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Sandeep Sheth
- Department of Pharmaceutical Sciences, Larkin University College of Pharmacy, Miami, FL, United States
| | - Ian Alberts
- Medical Microbiology, Immunology and Cell Biology (MMICB), Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Shree Patel
- Medical Microbiology, Immunology and Cell Biology (MMICB), Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Leonard P. Rybak
- Department of Surgery, Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Vickram Ramkumar
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, United States
- *Correspondence: Vickram Ramkumar,
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3
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Vlajkovic SM, Thorne PR. Purinergic Signalling in the Cochlea. Int J Mol Sci 2022; 23:ijms232314874. [PMID: 36499200 PMCID: PMC9741428 DOI: 10.3390/ijms232314874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022] Open
Abstract
The mammalian cochlea is the sensory organ of hearing with a delicate, highly organised structure that supports unique operating mechanisms. ATP release from the secretory tissues of the cochlear lateral wall (stria vascularis) triggers numerous physiological responses by activating P2 receptors in sensory, supporting and neural tissues. Two families of P2 receptors, ATP-gated ion channels (P2X receptors) and G protein-coupled P2Y receptors, activate intracellular signalling pathways that regulate cochlear development, homeostasis, sensory transduction, auditory neurotransmission and response to stress. Of particular interest is a purinergic hearing adaptation, which reflects the critical role of the P2X2 receptor in adaptive cochlear response to elevated sound levels. Other P2 receptors are involved in the maturation of neural processes and frequency selectivity refinement in the developing cochlea. Extracellular ATP signalling is regulated by a family of surface-located enzymes collectively known as "ectonucleotidases" that hydrolyse ATP to adenosine. Adenosine is a constitutive cell metabolite with an established role in tissue protection and regeneration. The differential activation of A1 and A2A adenosine receptors defines the cochlear response to injury caused by oxidative stress, inflammation, and activation of apoptotic pathways. A1 receptor agonism, A2A receptor antagonism, and increasing adenosine levels in cochlear fluids all represent promising therapeutic tools for cochlear rescue from injury and prevention of hearing loss.
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Affiliation(s)
- Srdjan M. Vlajkovic
- Department of Physiology and The Eisdell Moore Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Correspondence: ; Tel.: +64-9-9239782
| | - Peter R. Thorne
- Department of Physiology and The Eisdell Moore Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Section of Audiology, School of Population Health, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
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4
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Zhang Z, Chai R. Hear the sounds: The role of G Protein-Coupled Receptors in the cochlea. Am J Physiol Cell Physiol 2022; 323:C1088-C1099. [PMID: 35938679 DOI: 10.1152/ajpcell.00453.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sound is converted by hair cells in the cochlea into electrical signals, which are transmitted by spiral ganglion neurons (SGNs) and heard by the auditory cortex. G protein-coupled receptors (GPCRs) are crucial receptors that regulate a wide range of physiological functions in different organ and tissues. The research of GPCRs in the cochlea is essential for the understanding of the cochlea development, hearing disorders, and the treatment for hearing loss. Recently, several GPCRs have been found to play important roles in the cochlea. Frizzleds and Lgrs are dominant GPCRs that regulate stem cell self-renew abilities. Moreover, Frizzleds and Celsrs have been demonstrated to play core roles in the modulation of cochlear planar cell polarity (PCP). In addition, hearing loss can be caused by mutations of certain GPCRs, such as Vlgr1, Gpr156, S1P2 and Gpr126. And A1, A2A and CB2 activation by agonists have protective functions on noise- or drug-induced hearing loss. Here, we review the key findings of GPCR in the cochlea, and discuss the role of GPCR in the cochlea, such as stem cell fate, PCP, hearing loss, and hearing protection.
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Affiliation(s)
- Zhong Zhang
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, China
| | - Renjie Chai
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, China
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5
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van Dieken A, Staecker H, Schmitt H, Harre J, Pich A, Roßberg W, Lenarz T, Durisin M, Warnecke A. Bioinformatic Analysis of the Perilymph Proteome to Generate a Human Protein Atlas. Front Cell Dev Biol 2022; 10:847157. [PMID: 35573665 PMCID: PMC9096870 DOI: 10.3389/fcell.2022.847157] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 04/04/2022] [Indexed: 11/16/2022] Open
Abstract
The high complexity of the cellular architecture of the human inner ear and the inaccessibility for tissue biopsy hampers cellular and molecular analysis of inner ear disease. Sampling and analysis of perilymph may present an opportunity for improved diagnostics and understanding of human inner ear pathology. Analysis of the perilymph proteome from patients undergoing cochlear implantation was carried out revealing a multitude of proteins and patterns of protein composition that may enable characterisation of patients into subgroups. Based on existing data and databases, single proteins that are not present in the blood circulation were related to cells within the cochlea to allow prediction of which cells contribute to the individual perilymph proteome of the patients. Based on the results, we propose a human atlas of the cochlea. Finally, druggable targets within the perilymph proteome were identified. Understanding and modulating the human perilymph proteome will enable novel avenues to improve diagnosis and treatment of inner ear diseases.
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Affiliation(s)
- Alina van Dieken
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Hinrich Staecker
- Department of Otolaryngology, Head and Neck, Surgery, University of Kansas School of Medicine, Kansas City, KS, United States
| | - Heike Schmitt
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Jennifer Harre
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Andreas Pich
- Core Facility Proteomics, Hannover Medical School, Hannover, Germany
| | - Willi Roßberg
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Martin Durisin
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Athanasia Warnecke
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
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6
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Kim J, Hemachandran S, Cheng AG, Ricci AJ. Identifying targets to prevent aminoglycoside ototoxicity. Mol Cell Neurosci 2022; 120:103722. [PMID: 35341941 PMCID: PMC9177639 DOI: 10.1016/j.mcn.2022.103722] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 03/14/2022] [Accepted: 03/19/2022] [Indexed: 12/21/2022] Open
Abstract
Aminoglycosides are potent antibiotics that are commonly prescribed worldwide. Their use carries significant risks of ototoxicity by directly causing inner ear hair cell degeneration. Despite their ototoxic side effects, there are currently no approved antidotes. Here we review recent advances in our understanding of aminoglycoside ototoxicity, mechanisms of drug transport, and promising sites for intervention to prevent ototoxicity.
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Affiliation(s)
- Jinkyung Kim
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Sriram Hemachandran
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alan G Cheng
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Anthony J Ricci
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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7
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In vivo real-time imaging reveals megalin as the aminoglycoside gentamicin transporter into cochlea whose inhibition is otoprotective. Proc Natl Acad Sci U S A 2022; 119:2117946119. [PMID: 35197290 PMCID: PMC8892513 DOI: 10.1073/pnas.2117946119] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/05/2022] [Indexed: 01/01/2023] Open
Abstract
Aminoglycosides (AGs) are commonly used antibiotics that cause deafness through the irreversible loss of cochlear sensory hair cells (HCs). How AGs enter the cochlea and then target HCs remains unresolved. Here, we performed time-lapse multicellular imaging of cochlea in live adult hearing mice via a chemo-mechanical cochleostomy. The in vivo tracking revealed that systemically administered Texas Red-labeled gentamicin (GTTR) enters the cochlea via the stria vascularis and then HCs selectively. GTTR uptake into HCs was completely abolished in transmembrane channel-like protein 1 (TMC1) knockout mice, indicating mechanotransducer channel-dependent AG uptake. Blockage of megalin, the candidate AG transporter in the stria vascularis, by binding competitor cilastatin prevented GTTR accumulation in HCs. Furthermore, cilastatin treatment markedly reduced AG-induced HC degeneration and hearing loss in vivo. Together, our in vivo real-time tracking of megalin-dependent AG transport across the blood-labyrinth barrier identifies new therapeutic targets for preventing AG-induced ototoxicity.
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8
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Istradefylline Mitigates Age-Related Hearing Loss in C57BL/6J Mice. Int J Mol Sci 2021; 22:ijms22158000. [PMID: 34360766 PMCID: PMC8348536 DOI: 10.3390/ijms22158000] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 07/23/2021] [Accepted: 07/23/2021] [Indexed: 12/20/2022] Open
Abstract
Age-related hearing loss (ARHL) is the most common sensory disorder among older people, and yet, the treatment options are limited to medical devices such as hearing aids and cochlear implants. The high prevalence of ARHL mandates the development of treatment strategies that can prevent or rescue age-related cochlear degeneration. In this study, we investigated a novel pharmacological strategy based on inhibition of the adenosine A2A receptor (A2AR) in middle aged C57BL/6 mice prone to early onset ARHL. C57BL/6J mice were treated with weekly istradefylline (A2AR antagonist; 1 mg/kg) injections from 6 to 12 months of age. Auditory function was assessed using auditory brainstem responses (ABR) to tone pips (4–32 kHz). ABR thresholds and suprathreshold responses (wave I amplitudes and latencies) were evaluated at 6, 9, and 12 months of age. Functional outcomes were correlated with quantitative histological assessments of sensory hair cells. Cognitive function was assessed using the Morris water maze and the novel object recognition test, and the zero maze test was used to assess anxiety-like behaviour. Weekly injections of istradefylline attenuated ABR threshold shifts by approximately 20 dB at mid to high frequencies (16–32 kHz) but did not improve ABR suprathreshold responses. Istradefylline treatment improved hair cell survival in a turn-dependent manner, whilst the cognitive function was unaffected by istradefylline treatment. This study presents the first evidence for the rescue potential of istradefylline in ARHL and highlights the role of A2AR in development of age-related cochlear degeneration.
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9
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Fok C, Bogosanovic M, Pandya M, Telang R, Thorne PR, Vlajkovic SM. Regulator of G Protein Signalling 4 (RGS4) as a Novel Target for the Treatment of Sensorineural Hearing Loss. Int J Mol Sci 2020; 22:ijms22010003. [PMID: 33374915 PMCID: PMC7792627 DOI: 10.3390/ijms22010003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/16/2020] [Accepted: 12/19/2020] [Indexed: 12/20/2022] Open
Abstract
We and others have previously identified signalling pathways associated with the adenosine A1 receptor (A1R) as important regulators of cellular responses to injury in the cochlea. We have shown that the “post-exposure” treatment with adenosine A1R agonists confers partial protection against acoustic trauma and other forms of sensorineural hearing loss (SNHL). The aim of this study was to determine if increasing A1R responsiveness to endogenous adenosine would have the same otoprotective effect. This was achieved by pharmacological targeting of the Regulator of G protein Signalling 4 (RGS4). RGS proteins inhibit signal transduction pathways initiated by G protein-coupled receptors (GPCR) by enhancing GPCR deactivation and receptor desensitisation. A molecular complex between RGS4 and neurabin, an intracellular scaffolding protein expressed in neural and cochlear tissues, is the key negative regulator of A1R activity in the brain. In this study, Wistar rats (6–8 weeks) were exposed to traumatic noise (110 dBSPL, 8–16 kHz) for 2 h and a small molecule RGS4 inhibitor CCG-4986 was delivered intratympanically in a Poloxamer-407 gel formulation for sustained drug release 24 or 48 h after noise exposure. Intratympanic administration of CCG-4986 48 h after noise exposure attenuated noise-induced permanent auditory threshold shifts by up to 19 dB, whilst the earlier drug administration (24 h) led to even better preservation of auditory thresholds (up to 32 dB). Significant improvement of auditory thresholds and suprathreshold responses was linked to improved survival of sensorineural tissues and afferent synapses in the cochlea. Our studies thus demonstrate that intratympanic administration of CCG-4986 can rescue cochlear injury and hearing loss induced by acoustic overexposure. This research represents a novel paradigm for the treatment of various forms of SNHL based on regulation of GPCR.
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10
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Peng T, Peng JJ, Miao GY, Tan ZQ, Liu B, Zhou E. miR‑125/CDK2 axis in cochlear progenitor cell proliferation. Mol Med Rep 2020; 23:102. [PMID: 33300064 PMCID: PMC7723065 DOI: 10.3892/mmr.2020.11741] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 10/16/2020] [Indexed: 12/25/2022] Open
Abstract
Hearing loss ranks fourth among the principal causes of disability worldwide, and manipulation of progenitor cells may be a key strategy for hair cell regeneration. The present study investigated the role and mechanism of miR‑125 on the proliferation of cochlear progenitor cells (CPCs). CPCs were isolated from the cochleae of neonatal rats, and their morphology was observed. Furthermore, the differentiation ability of CPCs was determined by assessing the expression of 5‑bromodeoxyuridine (BrdU), nestin and myosin VII by immunofluorescence. The expression levels of miR‑125 and cyclin‑dependent kinase 2 (CDK2) as well as the cell proliferation of CPCs were assessed. In addition, following gain‑ and loss‑of‑function assays, the cell cycle was examined by flow cytometry, and the expression levels of miR‑125, CDK2, proliferating cell nuclear antigen (PCNA) and nestin were determined by reverse transcription‑quantitative PCR and western blotting. The binding sites between miR‑125 and CDK2 were predicted by TargetScan and identified by the dual luciferase reporter assay. The results demonstrated that different types of progenitor spheres were observed from CPCs with positive expression of BrdU, nestin and myosin VII. Following in vitro incubation for 2, 4 and 7 days, the spheres were enlarged, and CPC proliferation gradually increased and reached a plateau after further incubation for 3 days. Furthermore, the expression levels of nestin and PCNA in CPCs increased and then decreased during in vitro incubation for 2, 4 and 7 days. Following this incubation, the expression levels of miR‑125 in CPCs decreased; thereafter, its expression increased, and the expression pattern was different from that of CDK2. In addition, miR‑125 overexpression in CPCs decreased the expression of CDK2 and the number of cells in the S phase. Different expression patterns were found in CPCs in response to the miR‑125 knockdown. In addition, miR‑125 directly targeted CDK2. Simultaneous knockdown of miR‑125 and CDK2 enhanced CPC proliferation compared with CDK2 knockdown alone. Taken together, the findings from the present study suggested that miR‑125 may inhibit CPC proliferation by downregulating CDK2. The present study may provide a novel therapeutic direction for treatment of hearing loss.
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Affiliation(s)
- Tao Peng
- Department of Otolaryngology and Head and Neck Surgery, Hunan Provincial People's Hospital, First Affiliated Hospital of Hunan Normal University, Changsha, Hunan 410007, P.R. China
| | - Jing-Jing Peng
- Department of Obstetrics and Gynecology, Changsha Maternal and Child Health Care Hospital, Changsha, Hunan 410005, P.R. China
| | - Gang-Yong Miao
- Department of Otolaryngology and Head and Neck Surgery, Hunan Provincial People's Hospital, First Affiliated Hospital of Hunan Normal University, Changsha, Hunan 410007, P.R. China
| | - Zhi-Qiang Tan
- Department of Otolaryngology and Head and Neck Surgery, Hunan Provincial People's Hospital, First Affiliated Hospital of Hunan Normal University, Changsha, Hunan 410007, P.R. China
| | - Bin Liu
- Department of Otolaryngology and Head and Neck Surgery, Hunan Provincial People's Hospital, First Affiliated Hospital of Hunan Normal University, Changsha, Hunan 410007, P.R. China
| | - En Zhou
- Department of Otolaryngology and Head and Neck Surgery, Hunan Provincial People's Hospital, First Affiliated Hospital of Hunan Normal University, Changsha, Hunan 410007, P.R. China
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11
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Ashmore J. Tonotopy of cochlear hair cell biophysics (excl. mechanotransduction). CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2020.06.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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12
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Han BR, Lin SC, Espinosa K, Thorne PR, Vlajkovic SM. Inhibition of the Adenosine A 2A Receptor Mitigates Excitotoxic Injury in Organotypic Tissue Cultures of the Rat Cochlea. Cells 2019; 8:cells8080877. [PMID: 31408967 PMCID: PMC6721830 DOI: 10.3390/cells8080877] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 08/09/2019] [Accepted: 08/09/2019] [Indexed: 12/20/2022] Open
Abstract
The primary loss of cochlear glutamatergic afferent nerve synapses due to noise or ageing (cochlear neuropathy) often presents as difficulties in speech discrimination in noisy conditions (hidden hearing loss (HHL)). Currently, there is no treatment for this condition. Our previous studies in mice with genetic deletion of the adenosine A2A receptor (A2AR) have demonstrated better preservation of cochlear afferent synapses and spiral ganglion neurons after noise exposure compared to wildtype mice. This has informed our current targeted approach to cochlear neuroprotection based on pharmacological inhibition of the A2AR. Here, we have used organotypic tissue culture of the Wistar rat cochlea at postnatal day 6 (P6) to model excitotoxic injury induced by N-methyl-d-aspartate (NMDA)/kainic acid (NK) treatment for 2 h. The excitotoxic injury was characterised by a reduction in the density of neural processes immediately after NK treatment and loss of afferent synapses in the presence of intact sensory hair cells. The administration of istradefylline (a clinically approved A2AR antagonist) reduced deafferentation of inner hair cells and improved the survival of afferent synapses after excitotoxic injury. This study thus provides evidence that A2AR inhibition promotes cochlear recovery from excitotoxic injury, and may have implications for the treatment of cochlear neuropathy and prevention of HHL.
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Affiliation(s)
- Belinda Rx Han
- Department of Physiology and The Eisdell Moore Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Shelly Cy Lin
- Department of Physiology and The Eisdell Moore Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Kristan Espinosa
- Department of Physiology and The Eisdell Moore Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Peter R Thorne
- Department of Physiology and The Eisdell Moore Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Srdjan M Vlajkovic
- Department of Physiology and The Eisdell Moore Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
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