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Zhang Y, Lin G, Xue N, Wang Y, Du T, Liu H, Xiong W, Shang W, Wu H, Song L. Differential outcomes of high-fat diet on age-related rescaling of cochlear frequency place coding. FASEB J 2023; 37:e23167. [PMID: 37651093 DOI: 10.1096/fj.202300457rr] [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: 03/09/2023] [Revised: 08/01/2023] [Accepted: 08/14/2023] [Indexed: 09/01/2023]
Abstract
Auditory frequency coding is place-specific, which depends on the mechanical coupling of the basilar membrane-outer hair cell (OHC)-tectorial membrane network. Prestin-based OHC electromotility improves cochlear frequency selectivity and sensitivity. Cochlear amplification determines the frequency coding wherein discrete sound frequencies find a 'best' place along the cochlear length. Loss of OHC is the leading cause of age-related hearing loss (ARHL) and is the most common cause of sensorineural hearing loss and compromised speech perception. Lipid interaction with Prestin impacts OHC function. It has been established that high-fat diet (HFD) is associated with ARHL. To determine whether genetic background and metabolism preserve cochlear frequency place coding, we examined the effect of HFD in C57BL/6J (B6) and CBA/CaJ (CBA) on ARHL.We found a significant rescuing effect on ARHL in aged B6 HFD cohort. Prestin levels and cell sizes were better maintained in the experimental B6-HFD group. We also found that distortion product otoacoustic emission (DPOAE) group delay measurement was preserved, which suggested stable frequency place coding. In contrast, the response to HFD in the CBA cohort was modest with no appreciable benefit to hearing threshold. Notably, group delay was shortened with age along with the control. In addition, the frequency dependent OHC nonlinear capacitance gradient was most pronounced at young age but decreased with age. Cochlear RNA-seq analysis revealed differential TRPV1 expression and lipid homeostasis. Activation of TRPV1 and downregulation of arachidonic acid led to downregulation of inflammatory response in B6 HFD, which protects the cochlea from ARHL. The genetic background and metabolic state-derived changes in OHC morphology and function collectively contribute to a redefined cochlear frequency place coding and improved age-related pitch perception.
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Affiliation(s)
- Yu Zhang
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Guotong Lin
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Na Xue
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Yi Wang
- School of Life Sciences, Tsinghua University, Beijing, China
| | - Tingting Du
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Huihui Liu
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Wei Xiong
- Chinese Institute for Brain Research, Beijing, China
| | - Wei Shang
- Navy Clinical Medical School, Anhui Medical University, Hefei, China
- In Vitro Fertility (IVF) Center Department of Obstetrics and Gynecology, the Sixth Medical Center of PLA General Hospital, Beijing, China
- Department of Obstetrics and Gynecology, Chinese PLA General Hospital, Beijing, China
| | - Hao Wu
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Lei Song
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
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2
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Santos-Sacchi J, Tan W. On the frequency response of prestin charge movement in membrane patches. Biophys J 2022; 121:2371-2379. [PMID: 35598044 PMCID: PMC9279172 DOI: 10.1016/j.bpj.2022.05.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 04/14/2022] [Accepted: 05/17/2022] [Indexed: 11/18/2022] Open
Abstract
Outer hair cell (OHC) nonlinear membrane capacitance derives from voltage-dependent sensor charge movements within the membrane protein prestin (SLC26a5) that drive OHC electromotility. The ability of the protein to influence hearing depends on its reaction to membrane receptor potentials across auditory frequency. Estimates of prestin's frequency response have been evaluated by several groups out to tens of kHz in voltage-clamped macro-patches of OHC membrane. The response is a power function of frequency that is down 40 dB at 77 kHz. Despite these observations, concerns remain that the macro-patch approach is flawed due to mechanical constraints of pipette solution column load or patch size itself. In the absence of these influences, prestin's frequency response is posited by some to be ultrasonic in nature. Here we evaluate the influence of these putative confounding factors on prestin's frequency response. We show that neither pipette column height nor negative or positive pipette pressure substantially influence total sensor charge frequency response. Additionally, patch surface area has negligible influence. We conclude that the speed of voltage-driven conformational changes in prestin within the plasma membrane is accurately assessed with the macro-patch technique, permitting investigations of membrane characteristics that can substantially alter prestin's performance bandwidth. We illustrate significant alterations in bandwidth by perturbation of membrane fluidity and chloride anion concentration. Finally, we speculate that OHC membrane characteristics may differ along the tonotopic axis of the cochlea to tune nonlinear membrane capacitance frequency cutoffs.
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Affiliation(s)
- Joseph Santos-Sacchi
- Surgery (Otolaryngology), Neuroscience, and Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut.
| | - Winston Tan
- Surgery (Otolaryngology), Neuroscience, and Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
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Bharadwaj T, Schrauwen I, Rehman S, Liaqat K, Acharya A, Giese APJ, Nouel-Saied LM, Nasir A, Everard JL, Pollock LM, Zhu S, Bamshad MJ, Nickerson DA, Ali RH, Ullah A, Wali A, Ali G, Santos-Cortez RLP, Ahmed ZM, McDermott BM, Ansar M, Riazuddin S, Ahmad W, Leal SM. ADAMTS1, MPDZ, MVD, and SEZ6: candidate genes for autosomal recessive nonsyndromic hearing impairment. Eur J Hum Genet 2022; 30:22-33. [PMID: 34135477 PMCID: PMC8738740 DOI: 10.1038/s41431-021-00913-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 05/12/2021] [Accepted: 05/21/2021] [Indexed: 11/08/2022] Open
Abstract
Hearing impairment (HI) is a common disorder of sensorineural function with a highly heterogeneous genetic background. Although substantial progress has been made in the understanding of the genetic etiology of hereditary HI, many genes implicated in HI remain undiscovered. Via exome and Sanger sequencing of DNA samples obtained from consanguineous Pakistani families that segregate profound prelingual sensorineural HI, we identified rare homozygous missense variants in four genes (ADAMTS1, MPDZ, MVD, and SEZ6) that are likely the underlying cause of HI. Linkage analysis provided statistical evidence that these variants are associated with autosomal recessive nonsyndromic HI. In silico analysis of the mutant proteins encoded by these genes predicted structural, conformational or interaction changes. RNAseq data analysis revealed expression of these genes in the sensory epithelium of the mouse inner ear during embryonic, postnatal, and adult stages. Immunohistochemistry of the mouse cochlear tissue, further confirmed the expression of ADAMTS1, SEZ6, and MPDZ in the neurosensory hair cells of the organ of Corti, while MVD expression was more prominent in the spiral ganglion cells. Overall, supported by in silico mutant protein analysis, animal models, linkage analysis, and spatiotemporal expression profiling in the mouse inner ear, we propose four new candidate genes for HI and expand our understanding of the etiology of HI.
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Affiliation(s)
- Thashi Bharadwaj
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Isabelle Schrauwen
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Sakina Rehman
- Department of Otorhinolaryngology - Head and Neck Surgery, University of Maryland, Baltimore, MD, USA
| | - Khurram Liaqat
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Anushree Acharya
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Arnaud P J Giese
- Department of Otorhinolaryngology - Head and Neck Surgery, University of Maryland, Baltimore, MD, USA
| | - Liz M Nouel-Saied
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Abdul Nasir
- Synthetic Protein Engineering Lab (SPEL), Department of Molecular Science and Technology, Ajou University, Suwon, South Korea
| | - Jenna L Everard
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Lana M Pollock
- Case Western Reserve University, Department of Otolaryngology, Head and Neck Surgery, Cleveland, OH, USA
| | - Shaoyuan Zhu
- Case Western Reserve University, Department of Otolaryngology, Head and Neck Surgery, Cleveland, OH, USA
| | - Michael J Bamshad
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Department of Pediatrics, University of Washington, Seattle, WA, USA
| | | | - Raja Hussain Ali
- Department of Hematology/Oncology, Boston Children's Hospital, Boston, MA, USA
| | - Asmat Ullah
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Abdul Wali
- Department of Biotechnology and Informatics, Faculty of Life Sciences and Informatics, BUITEMS, Quetta, Pakistan
| | - Ghazanfar Ali
- Department of Biotechnology, University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan
| | - Regie Lyn P Santos-Cortez
- Department of Otolaryngology - Head and Neck Surgery, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Zubair M Ahmed
- Department of Otorhinolaryngology - Head and Neck Surgery, University of Maryland, Baltimore, MD, USA
| | - Brian M McDermott
- Case Western Reserve University, Department of Otolaryngology, Head and Neck Surgery, Cleveland, OH, USA
| | - Muhammad Ansar
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Saima Riazuddin
- Department of Otorhinolaryngology - Head and Neck Surgery, University of Maryland, Baltimore, MD, USA
| | - Wasim Ahmad
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Suzanne M Leal
- Center for Statistical Genetics, Gertrude H. Sergievsky Center, and the Department of Neurology, Columbia University Medical Center, New York, NY, USA.
- Taub Institute for Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, New York, NY, USA.
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George SS, Steele CR, Ricci AJ. Rat Auditory Inner Hair Cell Mechanotransduction and Stereociliary Membrane Diffusivity Are Similarly Modulated by Calcium. iScience 2020; 23:101773. [PMID: 33294782 PMCID: PMC7689183 DOI: 10.1016/j.isci.2020.101773] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/03/2020] [Accepted: 11/03/2020] [Indexed: 11/16/2022] Open
Abstract
The lipid bilayer plays a pivotal role in force transmission to many mechanically-gated channels. We developed the technology to monitor membrane diffusivity in order to test the hypothesis positing that Ca2+ regulates open probability (P o) of cochlear hair cell mechanotransduction (MET) channels via the plasma membrane. The stereociliary membrane was more diffusive (9x) than the basolateral membrane. Elevating intracellular Ca2+ buffering or lowering extracellular Ca2+ reduced stereociliary diffusivity and increased MET P o. In contrast, prolonged depolarization increased stereociliary diffusivity and reduced MET P o. No comparable effects were noted for soma measurements. Although MET channels are located in the shorter stereocilia rows, both rows had similar baseline diffusivity and showed similar responses to Ca2+ manipulations and MET channel blocks, suggesting that diffusivity is independent of MET. Together, these data suggest that the stereociliary membrane is a component of a calcium-modulated viscoelastic-like element regulating hair cell mechanotransduction.
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Affiliation(s)
- Shefin S George
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, 240 Pasteur Drive, Stanford, CA 94305, USA
| | - Charles R Steele
- Department of Mechanical Engineering, Building 520, 440 Escondido Mall, Stanford University, CA 94305, USA
| | - Anthony J Ricci
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, 240 Pasteur Drive, Stanford, CA 94305, USA.,Department of Molecular and Cellular Physiology, School of Medicine, Stanford University, 291 Campus Drive, Stanford, CA 94305, USA
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5
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Fetoni AR, Paciello F, Rolesi R, Paludetti G, Troiani D. Targeting dysregulation of redox homeostasis in noise-induced hearing loss: Oxidative stress and ROS signaling. Free Radic Biol Med 2019; 135:46-59. [PMID: 30802489 DOI: 10.1016/j.freeradbiomed.2019.02.022] [Citation(s) in RCA: 111] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 02/04/2019] [Accepted: 02/18/2019] [Indexed: 12/20/2022]
Abstract
Hearing loss caused by exposure to recreational and occupational noise remains a worldwide disabling condition and dysregulation of redox homeostasis is the hallmark of cochlear damage induced by noise exposure. In this review we discuss the dual function of ROS to both promote cell damage (oxidative stress) and cell adaptive responses (ROS signaling) in the cochlea undergoing a stressful condition such as noise exposure. We focus on animal models of noise-induced hearing loss (NIHL) and on the function of exogenous antioxidants to maintaining a physiological role of ROS signaling by distinguishing the effect of exogenous "direct" antioxidants (i.e. CoQ10, NAC), that react with ROS to decrease oxidative stress, from the exogenous "indirect" antioxidants (i.e. nutraceutics and phenolic compounds) that can activate cellular redox enzymes through the Keap1-Nrf2-ARE pathway. The anti-inflammatory properties of Nrf2 signaling are discussed in relation to the ROS/inflammation interplay in noise exposure. Unveiling the mechanisms of ROS regulating redox-associated signaling pathways is essential in providing relevant targets for innovative and effective therapeutic strategies against NIHL.
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Affiliation(s)
- Anna Rita Fetoni
- Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy; Institute of Otolaryngology, Università Cattolica del Sacro Cuore, Rome, Italy; CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy
| | - Fabiola Paciello
- Institute of Otolaryngology, Università Cattolica del Sacro Cuore, Rome, Italy; CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy
| | - Rolando Rolesi
- Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy; Institute of Otolaryngology, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Gaetano Paludetti
- Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy; Institute of Otolaryngology, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Diana Troiani
- Institute of Human Physiology, Università Cattolica del Sacro Cuore, Rome, Italy.
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6
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Wu N, Husile H, Yang L, Cao Y, Li X, Huo W, Bai H, Liu Y, Wu Q. A novel pathogenic variant in OSBPL2 linked to hereditary late-onset deafness in a Mongolian family. BMC MEDICAL GENETICS 2019; 20:43. [PMID: 30894143 PMCID: PMC6425609 DOI: 10.1186/s12881-019-0781-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 03/11/2019] [Indexed: 11/10/2022]
Abstract
BACKGROUND To investigate the clinical features and the underlying causal gene of a family with hereditary late-onset deafness in Inner Mongolia of China, and to provide evidence for the early genetic screening and diagnosis of this disease. METHODS Family data were collected to draw a pedigree. Audiological testing and physical examination of the family members were conducted following questionnaire. Genomic DNA was extracted from peripheral blood of 5 family members (3 patients and 2 normal control) and subjected to whole genome sequencing for identifying deafness casual genes. The pathogenic variant in the deafness gene was further confirmed by Sanger sequencing. RESULTS The family is composed of a total of 6 generations, with 53 traceable individuals. In this family,19 of them were diagnosed with post lingual deafness with the age of onset between 10 and 40 years, displaying delayed and progressive hearing loss. Patients with hearing loss showed bilateral symmetry and mild to severe sensorineural deafness. The pattern of deafness inheritance in this family is autosomal dominant. Whole genome sequencing identified a novel pathogenic frameshift mutation, c.158_159delAA (p.Gln53Arg fs*100) in the gene OSBPL2 (Oxysterol-binding protein-related protein 2, NM_144498.2), which is absent from genomic data of 201 unrelated normal subjects. This pathogenic variant was further validated by Sanger sequencing, and was found to co-segregate in this family. CONCLUSIONS Whole genome sequencing identified a two-nucleotide deletion in OSBPL2 (c.158_159delAA) as the pathogenic variant for deafness in the family. Our finding expands the mutational spectrum of OSBPL2 and contributes to the pathogenic variant list in genetic counseling for deafness screening.
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Affiliation(s)
- Ningjin Wu
- Affiliated Hospital of Inner Mongolia University for the Nationalities, Tongliao, 028000, China.,Xiangya School of Medicine, Central South University, Changsha, 410013, China
| | - Husile Husile
- Affiliated Hospital of Inner Mongolia University for the Nationalities, Tongliao, 028000, China.,Inner Mongolia Engineering Research Center of Personalized Medicine, Tongliao, 028000, China
| | - Liqing Yang
- Affiliated Hospital of Inner Mongolia University for the Nationalities, Tongliao, 028000, China.,Inner Mongolia Engineering Research Center of Personalized Medicine, Tongliao, 028000, China
| | - Yaning Cao
- School of Life Science, Inner Mongolia University, Hohhot, 010021, China
| | - Xing Li
- School of Life Science, Inner Mongolia University for the Nationalities, Tongliao, 028000, China
| | - Wenyan Huo
- Affiliated Hospital of Inner Mongolia University for the Nationalities, Tongliao, 028000, China.,Inner Mongolia Engineering Research Center of Personalized Medicine, Tongliao, 028000, China
| | - Haihua Bai
- Inner Mongolia Engineering Research Center of Personalized Medicine, Tongliao, 028000, China.,School of Life Science, Inner Mongolia University for the Nationalities, Tongliao, 028000, China
| | - Yangjian Liu
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA.
| | - Qizhu Wu
- Affiliated Hospital of Inner Mongolia University for the Nationalities, Tongliao, 028000, China. .,Inner Mongolia Engineering Research Center of Personalized Medicine, Tongliao, 028000, China.
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7
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Crumling MA, King KA, Duncan RK. Cyclodextrins and Iatrogenic Hearing Loss: New Drugs with Significant Risk. Front Cell Neurosci 2017; 11:355. [PMID: 29163061 PMCID: PMC5676048 DOI: 10.3389/fncel.2017.00355] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 10/26/2017] [Indexed: 12/18/2022] Open
Abstract
Cyclodextrins are a family of cyclic oligosaccharides with widespread usage in medicine, industry and basic sciences owing to their ability to solubilize and stabilize guest compounds. In medicine, cyclodextrins primarily act as a complexing vehicle and consequently serve as powerful drug delivery agents. Recently, uncomplexed cyclodextrins have emerged as potent therapeutic compounds in their own right, based on their ability to sequester and mobilize cellular lipids. In particular, 2-hydroxypropyl-β-cyclodextrin (HPβCD) has garnered attention because of its cholesterol chelating properties, which appear to treat a rare neurodegenerative disorder and to promote atherosclerosis regression related to stroke and heart disease. Despite the potential health benefits, use of HPβCD has been linked to significant hearing loss in several species, including humans. Evidence in mice supports a rapid onset of hearing loss that is dose-dependent. Ototoxicity can occur following central or peripheral drug delivery, with either route resulting in the preferential loss of cochlear outer hair cells (OHCs) within hours of dosing. Inner hair cells and spiral ganglion cells are spared at doses that cause ~85% OHC loss; additionally, no other major organ systems appear adversely affected. Evidence from a first-to-human phase 1 clinical trial mirrors animal studies to a large extent, indicating rapid onset and involvement of OHCs. All patients in the trial experienced some permanent hearing loss, although a temporary loss of function can be observed acutely following drug delivery. The long-term impact of HPβCD use as a maintenance drug, and the mechanism(s) of ototoxicity, are unknown. β-cyclodextrins preferentially target membrane cholesterol, but other lipid species and proteins may be directly or indirectly involved. Moreover, as cholesterol is ubiquitous in cell membranes, it remains unclear why OHCs are preferentially susceptible to HPβCD. It is possible that HPβCD acts upon several targets—for example, ion channels, tight junctions (TJ), membrane integrity, and bioenergetics—that collectively increase the sensitivity of OHCs over other cell types.
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Affiliation(s)
- Mark A Crumling
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, United States
| | - Kelly A King
- Audiology Unit, Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, United States
| | - R Keith Duncan
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, United States
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Diflunisal inhibits prestin by chloride-dependent mechanism. PLoS One 2017; 12:e0183046. [PMID: 28817613 PMCID: PMC5560734 DOI: 10.1371/journal.pone.0183046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 07/30/2017] [Indexed: 11/19/2022] Open
Abstract
The motor protein prestin is a member of the SLC26 family of anion antiporters and is essential to the electromotility of cochlear outer hair cells and for hearing. The only direct inhibitor of electromotility and the associated charge transfer is salicylate, possibly through direct interaction with an anion-binding site on prestin. In a screen to identify other inhibitors of prestin activity, we explored the effect of the non-steroid anti-inflammatory drug diflunisal, which is a derivative of salicylate. We recorded prestin activity by whole-cell patch clamping HEK cells transiently expressing prestin and mouse outer hair cells. We monitored the impact of diflunisal on the prestin-dependent non-linear capacitance and electromotility. We found that diflunisal triggers two prestin-associated effects: a chloride independent increase in the surface area and the specific capacitance of the membrane, and a chloride dependent inhibition of the charge transfer and the electromotility in outer hair cells. We conclude that diflunisal affects the cell membrane organization and inhibits prestin-associated charge transfer and electromotility at physiological chloride concentrations. The inhibitory effects on hair cell function are noteworthy given the proposed use of diflunisal to treat neurodegenerative diseases.
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Pirodda A, Brandolini C, Raimondi MC, Pelligra I, Strocchi E, Cicero AF, Rosticci M, Borghi C. Cardiovascular risk factors and hearing impairment: a non-automatic correlation. HEARING, BALANCE AND COMMUNICATION 2016. [DOI: 10.1080/21695717.2016.1236597] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Antonio Pirodda
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy
| | - Cristina Brandolini
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy
| | - Maria Chiara Raimondi
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy
| | - Irene Pelligra
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy
| | - Enrico Strocchi
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
| | - Arrigo F.G. Cicero
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
| | - Martina Rosticci
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
| | - Claudio Borghi
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
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10
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Membrane prestin expression correlates with the magnitude of prestin-associated charge movement. Hear Res 2016; 339:50-9. [PMID: 27262187 DOI: 10.1016/j.heares.2016.05.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Revised: 05/14/2016] [Accepted: 05/26/2016] [Indexed: 11/20/2022]
Abstract
Full expression of electromotility, generation of non-linear capacitance (NLC), and high-acuity mammalian hearing require prestin function in the lateral wall of cochlear outer hair cells (OHCs). Estimates of the number of prestin molecules in the OHC membrane vary, and a consensus has not emerged about the correlation between prestin expression and prestin-associated charge movement in the OHC. Using an inducible prestin-expressing cell line, we demonstrate that the charge density, but not the voltage at peak capacitance, directly correlates with the amount of prestin in the plasma membrane. This correlation is evident in studies involving a controlled increase of prestin expression with time after induction and inducer dose-response. Conversely, membrane prestin levels and charge density gradually decline together following the reduction of prestin levels from a steady state by removal of the inducer. Thus, charge density directly correlates with the level of membrane prestin expression, whereas changing membrane levels of prestin have no effect on the voltage at peak capacitance in this inducible prestin-expressing cell line.
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11
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Maulucci G, Troiani D, Eramo SLM, Paciello F, Podda MV, Paludetti G, Papi M, Maiorana A, Palmieri V, De Spirito M, Fetoni AR. Time evolution of noise induced oxidation in outer hair cells: role of NAD(P)H and plasma membrane fluidity. Biochim Biophys Acta Gen Subj 2014; 1840:2192-202. [PMID: 24735797 DOI: 10.1016/j.bbagen.2014.04.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 03/25/2014] [Accepted: 04/07/2014] [Indexed: 01/24/2023]
Abstract
BACKGROUND Noise exposure impairs outer hair cells (OHCs). The common basis for OHC dysfunction and loss by acoustic over-stimulation is represented by reactive oxygen species (ROS) overload that may affect the membrane structural organization through generation of lipid peroxidation. METHODS Here we investigated in OHC different functional zones the mechanisms linking metabolic functional state (NAD(P)H intracellular distribution) to the generation of lipid peroxides and to the physical state of membranes by two photon fluorescence microscopy. RESULTS In OHCs of control animals, a more oxidized NAD(P)H redox state is associated to a less fluid plasma membrane structure. Acoustic trauma induces a topologically differentiated NAD(P)H oxidation in OHC rows, which is damped between 1 and 6h. Peroxidation occurs after ~4h from noise insult, while ROS are produced in the first 0.2h and damage cells for a period of time after noise exposure has ended (~7.5h) when a decrease of fluidity of OHC plasma membrane occurs. OHCs belonging to inner rows, characterized by a lower metabolic activity with respect to other rows, show less severe metabolic impairment. CONCLUSIONS Our data indicate that plasma membrane fluidity is related to NAD(P)H redox state and lipid peroxidation in hair cells. GENERAL SIGNIFICANCE Our results could pave the way for therapeutic intervention targeting the onset of redox umbalance.
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Affiliation(s)
| | - Diana Troiani
- Istituto di Fisiologia, Università Cattolica (UCSC), Roma, Italy.
| | | | - Fabiola Paciello
- Dipartimento di Scienze Chirurgiche per le patologie della testa e del collo, Università Cattolica (UCSC), Roma, Italy
| | | | - Gaetano Paludetti
- Dipartimento di Scienze Chirurgiche per le patologie della testa e del collo, Università Cattolica (UCSC), Roma, Italy
| | | | | | | | | | - Anna Rita Fetoni
- Dipartimento di Scienze Chirurgiche per le patologie della testa e del collo, Università Cattolica (UCSC), Roma, Italy
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12
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Kamar RI, Organ-Darling LE, Raphael RM. Membrane cholesterol strongly influences confined diffusion of prestin. Biophys J 2012; 103:1627-36. [PMID: 23083705 DOI: 10.1016/j.bpj.2012.07.052] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 07/18/2012] [Accepted: 07/25/2012] [Indexed: 01/04/2023] Open
Abstract
Prestin is the membrane motor protein that drives outer hair cell (OHC) electromotility, a process that is essential for mammalian hearing. Prestin function is sensitive to membrane cholesterol levels, and numerous studies have suggested that prestin localizes in cholesterol-rich membrane microdomains. Previously, fluorescence recovery after photobleaching experiments were performed in HEK cells expressing prestin-GFP after cholesterol manipulations, and revealed evidence of transient confinement. To further characterize this apparent confined diffusion of prestin, we conjugated prestin to a photostable fluorophore (tetramethylrhodamine) and performed single-molecule fluorescence microscopy. Using single-particle tracking, we determined the microscopic diffusion coefficient from the full time course of the mean-squared deviation. Our results indicate that prestin undergoes diffusion in confinement regions, and that depletion of membrane cholesterol increases confinement size and decreases confinement strength. By interpreting the data in terms of a mathematical model of hop-diffusion, we quantified these cholesterol-induced changes in membrane organization. A complementary analysis of the distribution of squared displacements confirmed that cholesterol depletion reduces prestin confinement. These findings support the hypothesis that prestin function is intimately linked to membrane organization, and further promote a regulatory role for cholesterol in OHC and auditory function.
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Affiliation(s)
- R I Kamar
- Department of Physics and Astronomy, Rice University, Houston, Texas, USA
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13
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Gross J, Stute K, Moller R, Fuchs J, Amarjargal N, Pohl EE, Angerstein M, Smorodchenko A, Mazurek B. Expression of prestin and Gata-3,-2,-1 mRNA in the rat organ of Corti during the postnatal period and in culture. Hear Res 2009; 261:9-21. [PMID: 20006695 DOI: 10.1016/j.heares.2009.12.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 11/16/2009] [Accepted: 12/05/2009] [Indexed: 01/15/2023]
Abstract
Based on observations that mutations of GATA-3 are responsible for the HDR-syndrome (hypoparathyroidism, deafness, renal defects) and that GATA-transcription factors have an important role to play in inner ear development, we hypothesized that these transcription factors may be involved in regulatory changes of prestin transcription. To prove this, we examined in parallel the expression of mRNA of prestin and Gata-3,-2 and Gata-1 in the organ of Corti during early postnatal development of rats and in organotypic cultures. Remarkable relations are observed between prestin and Gata-3,-2 expression in organ of Corti preparations in vivo and in vitro: (i) Gata-3,-2 expression display similar apical-basal gradients as prestin mRNA levels. (ii) The prestin expression increases between postnatal day two and postnatal day eight by a factor of about four in the apical and middle segments and by a factor of two in the basal part. Highly significant Pearson correlation coefficients were observed between Gata-3,-2 mRNA and prestin levels when the data were evaluated by regression analyses. (iii) Parallel changes of prestin mRNA and Gata-3,-2 mRNA levels were observed in response to thyroid hormone and to gemfibrozil application. These observations suggest a regulatory role played by the Gata-3,-2 transcription factors in prestin expression.
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Affiliation(s)
- Johann Gross
- Molecular Biology Research Laboratory, Department of Otorhinolaryngology, Institute of Cell- and Neurobiology, Charité-Universitätsmedizin Berlin, 10117 Berlin, Charitéplatz 1, Germany.
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14
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McGuire RM, Liu H, Pereira FA, Raphael RM. Cysteine mutagenesis reveals transmembrane residues associated with charge translocation in prestin. J Biol Chem 2009; 285:3103-13. [PMID: 19926791 DOI: 10.1074/jbc.m109.053249] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The solute carrier transmembrane protein prestin (SLC26A5) drives an active electromechanical transduction process in cochlear outer hair cells that increases hearing sensitivity and frequency discrimination in mammals. A large intramembraneous charge movement, the nonlinear capacitance (NLC), is the electrical signature of prestin function. The transmembrane domain (TMD) helices and residues involved in the intramembrane charge displacement remain unknown. We have performed cysteine-scanning mutagenesis with serine or valine replacement to investigate the importance of cysteine residues to prestin structure and function. The distribution of oligomeric states and membrane abundance of prestin was also probed to investigate whether cysteine residues participate in prestin oligomerization and/or NLC. Our results reveal that 1) Cys-196 (TMD 4) and Cys-415 (TMD 10) do not tolerate serine replacement, and thus maintaining hydrophobicity at these locations is important for the mechanism of charge movement; 2) Cys-260 (TMD 6) and Cys-381 (TMD 9) tolerate serine replacement and are probably water-exposed; and 3) if disulfide bonds are present, they do not serve a functional role as measured via NLC. These novel findings are consistent with a recent structural model, which proposes that prestin contains an occluded aqueous pore, and we posit that the orientations of transmembrane domain helices 4 and 10 are essential for proper prestin function.
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Affiliation(s)
- Ryan M McGuire
- Department of Bioengineering, Rice University, Houston, Texas 77005, USA
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15
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Mazurek B, Haupt H, Joachim R, Klapp BF, Stöver T, Szczepek AJ. Stress induces transient auditory hypersensitivity in rats. Hear Res 2009; 259:55-63. [PMID: 19840840 DOI: 10.1016/j.heares.2009.10.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 07/09/2009] [Accepted: 10/13/2009] [Indexed: 12/31/2022]
Abstract
Exposure to harsh environment induces stress reactions that increase probability of survival. Stress influences the endocrine, nervous and immune systems and affects the functioning of a variety of organs. Numerous researchers demonstrated that a 24-h exposure to an acoustic rodent repellent provokes stress reaction in exposed animals. In addition to the activated hypothalamic-pituitary-adrenal (HPA) axis, exposed animals had pathological reactions in the reproductive organs, bronchia and skin. Here, we examined the effect of above stress model on the auditory system of Wistar rats. We found that 24-h stress decreases the thresholds and increases the amplitudes of auditory brainstem responses and distortion product otoacoustic emissions. Resultant auditory hypersensitivity was transient and most pronounced between 3 and 6h post-stress, returning to control levels one week later. The concentration of corticosterone and tumor necrosis factor alpha was systemically elevated in stressed animals between 3 and 6h post-stress, confirming the activation of the HPA axis. In addition, expression of the HPA-axis-associated genes: glucocorticoid receptor (GR) and hypoxia-inducible factor 1 alpha (Hif1a) was modulated in the auditory tissues. In detail, in the inferior colliculus, we found an up-regulation of GR mRNA 3h post-stress and continuous up-regulation of Hif1a up to 24h post-stress. In the spiral ganglion, we found no differences in gene expression between stressed and control animals. In the organ of Corti, expression of GR mRNA remained stable, whereas that of Hif1a was significantly down-regulated one week after stress. In addition, the expression of an outer hair cell marker prestin was significantly up-regulated 6h post-stress. We conclude that 24-h stress induces transient hypersensitivity of the auditory system and modulates gene expression in a tissue-specific manner. Stress-induced auditory hypersensitivity could have evolutionary consequence by giving animals an advantage of hearing better under stress conditions.
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Affiliation(s)
- Birgit Mazurek
- Molecular Biology Research Laboratory, Department of Otorhinolaryngology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
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