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Lee JH, Park S, Perez-Flores MC, Chen Y, Kang M, Choi J, Levine L, Gratton MA, Zhao J, Notterpek L, Yamoah EN. Demyelination and Na + Channel Redistribution Underlie Auditory and Vestibular Dysfunction in PMP22-Null Mice. eNeuro 2024; 11:ENEURO.0462-23.2023. [PMID: 38378628 PMCID: PMC11059428 DOI: 10.1523/eneuro.0462-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Revised: 12/14/2023] [Accepted: 12/15/2023] [Indexed: 02/22/2024] Open
Abstract
Altered expression of peripheral myelin protein 22 (PMP22) results in demyelinating peripheral neuropathy. PMP22 exhibits a highly restricted tissue distribution with marked expression in the myelinating Schwann cells of peripheral nerves. Auditory and vestibular Schwann cells and the afferent neurons also express PMP22, suggesting a unique role in hearing and balancing. Indeed, neuropathic patients diagnosed with PMP22-linked hereditary neuropathies often present with auditory and balance deficits, an understudied clinical complication. To investigate the mechanism by which abnormal expression of PMP22 may cause auditory and vestibular deficits, we studied gene-targeted PMP22-null mice. PMP22-null mice exhibit an unsteady gait, have difficulty maintaining balance, and live for only ∼3-5 weeks relative to unaffected littermates. Histological analysis of the inner ear revealed reduced auditory and vestibular afferent nerve myelination and profound Na+ channel redistribution without PMP22. Yet, Na+ current density was unaltered, in stark contrast to increased K+ current density. Atypical postsynaptic densities and a range of neuronal abnormalities in the organ of Corti were also identified. Analyses of auditory brainstem responses (ABRs) and vestibular sensory-evoked potential (VsEP) revealed that PMP22-null mice had auditory and vestibular hypofunction. These results demonstrate that PMP22 is required for hearing and balance, and the protein is indispensable for the formation and maintenance of myelin in the peripheral arm of the eighth nerve. Our findings indicate that myelin abnormalities and altered signal propagation in the peripheral arm of the auditory nerve are likely causes of auditory deficits in patients with PMP22-linked neuropathies.
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Affiliation(s)
- Jeong Han Lee
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
| | - Seojin Park
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
- Prestige BioPharma, Busan 67264, South Korea
| | - Maria C Perez-Flores
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
| | - Yingying Chen
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
| | - Mincheol Kang
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
- Prestige BioPharma, Busan 67264, South Korea
| | - Jinsil Choi
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
| | - Lauren Levine
- Program in Audiology and Communication Sciences, Washington University, St. Louis 63110, Missouri
| | | | - Jie Zhao
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
| | - Lucia Notterpek
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
| | - Ebenezer N Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
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Lye J, Delaney DS, Leith FK, Sardesai VS, McLenachan S, Chen FK, Atlas MD, Wong EYM. Recent Therapeutic Progress and Future Perspectives for the Treatment of Hearing Loss. Biomedicines 2023; 11:3347. [PMID: 38137568 PMCID: PMC10741758 DOI: 10.3390/biomedicines11123347] [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: 11/16/2023] [Revised: 12/06/2023] [Accepted: 12/11/2023] [Indexed: 12/24/2023] Open
Abstract
Up to 1.5 billion people worldwide suffer from various forms of hearing loss, with an additional 1.1 billion people at risk from various insults such as increased consumption of recreational noise-emitting devices and ageing. The most common type of hearing impairment is sensorineural hearing loss caused by the degeneration or malfunction of cochlear hair cells or spiral ganglion nerves in the inner ear. There is currently no cure for hearing loss. However, emerging frontier technologies such as gene, drug or cell-based therapies offer hope for an effective cure. In this review, we discuss the current therapeutic progress for the treatment of hearing loss. We describe and evaluate the major therapeutic approaches being applied to hearing loss and summarize the key trials and studies.
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Affiliation(s)
- Joey Lye
- Hearing Therapeutics, Ear Science Institute Australia, Nedlands, WA 6009, Australia; (J.L.); (D.S.D.); (F.K.L.); (V.S.S.); (M.D.A.)
- Centre for Ear Sciences, Medical School, The University of Western Australia, Nedlands, WA 6009, Australia
| | - Derek S. Delaney
- Hearing Therapeutics, Ear Science Institute Australia, Nedlands, WA 6009, Australia; (J.L.); (D.S.D.); (F.K.L.); (V.S.S.); (M.D.A.)
- Faculty of Health Sciences, Curtin Health Innovation Research Institute, Curtin University, Bentley, WA 6102, Australia
| | - Fiona K. Leith
- Hearing Therapeutics, Ear Science Institute Australia, Nedlands, WA 6009, Australia; (J.L.); (D.S.D.); (F.K.L.); (V.S.S.); (M.D.A.)
- Centre for Ear Sciences, Medical School, The University of Western Australia, Nedlands, WA 6009, Australia
| | - Varda S. Sardesai
- Hearing Therapeutics, Ear Science Institute Australia, Nedlands, WA 6009, Australia; (J.L.); (D.S.D.); (F.K.L.); (V.S.S.); (M.D.A.)
| | - Samuel McLenachan
- Ocular Tissue Engineering Laboratory, Lions Eye Institute, Nedlands, WA 6009, Australia; (S.M.); (F.K.C.)
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, Nedlands, WA 6009, Australia
| | - Fred K. Chen
- Ocular Tissue Engineering Laboratory, Lions Eye Institute, Nedlands, WA 6009, Australia; (S.M.); (F.K.C.)
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, Nedlands, WA 6009, Australia
- Vitroretinal Surgery, Royal Perth Hospital, Perth, WA 6000, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, VIC 3002, Australia
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC 3002, Australia
| | - Marcus D. Atlas
- Hearing Therapeutics, Ear Science Institute Australia, Nedlands, WA 6009, Australia; (J.L.); (D.S.D.); (F.K.L.); (V.S.S.); (M.D.A.)
- Centre for Ear Sciences, Medical School, The University of Western Australia, Nedlands, WA 6009, Australia
| | - Elaine Y. M. Wong
- Hearing Therapeutics, Ear Science Institute Australia, Nedlands, WA 6009, Australia; (J.L.); (D.S.D.); (F.K.L.); (V.S.S.); (M.D.A.)
- Centre for Ear Sciences, Medical School, The University of Western Australia, Nedlands, WA 6009, Australia
- Curtin Medical School, Faculty of Health Sciences, Curtin University, Bentley, WA 6102, Australia
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Ren J, Sun Y, Dai B, Song W, Tan T, Guo L, Cao H, Wu Y, Hu W, Wang Z, Haiping D. Association between Ca2+ Signaling Pathway-Related Gene Polymorphism and Age-Related Hearing Loss in Qingdao Chinese Elderly. RUSS J GENET+ 2022. [DOI: 10.1134/s1022795422100076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Perez-Flores MC, Verschooten E, Lee JH, Kim HJ, Joris PX, Yamoah EN. Intrinsic mechanical sensitivity of mammalian auditory neurons as a contributor to sound-driven neural activity. eLife 2022; 11:74948. [PMID: 35266451 PMCID: PMC8942473 DOI: 10.7554/elife.74948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 03/09/2022] [Indexed: 11/18/2022] Open
Abstract
Mechanosensation – by which mechanical stimuli are converted into a neuronal signal – is the basis for the sensory systems of hearing, balance, and touch. Mechanosensation is unmatched in speed and its diverse range of sensitivities, reaching its highest temporal limits with the sense of hearing; however, hair cells (HCs) and the auditory nerve (AN) serve as obligatory bottlenecks for sounds to engage the brain. Like other sensory neurons, auditory neurons use the canonical pathway for neurotransmission and millisecond-duration action potentials (APs). How the auditory system utilizes the relatively slow transmission mechanisms to achieve ultrafast speed, and high audio-frequency hearing remains an enigma. Here, we address this paradox and report that the mouse, and chinchilla, AN are mechanically sensitive, and minute mechanical displacement profoundly affects its response properties. Sound-mimicking sinusoidal mechanical and electrical current stimuli affect phase-locked responses. In a phase-dependent manner, the two stimuli can also evoke suppressive responses. We propose that mechanical sensitivity interacts with synaptic responses to shape responses in the AN, including frequency tuning and temporal phase locking. Combining neurotransmission and mechanical sensation to control spike patterns gives the mammalian AN a secondary receptor role, an emerging theme in primary neuronal functions.
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Affiliation(s)
| | - Eric Verschooten
- Laboratory of Auditory Neurophysiology, University of Leuven, Leuven, Belgium
| | | | | | - Philip X Joris
- Laboratory of Auditory Neurophysiology, University of Leuven, Leuven, Belgium
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Geng Q, Li H, Zhang H, Lu M, Liu J, Wang F, Shen H, Yamoah EN, Jia Z, Lv P. Association between Ca v3 channel upregulation in spiral ganglion neurons and age-dependent hearing loss. Exp Gerontol 2021; 151:111429. [PMID: 34052348 DOI: 10.1016/j.exger.2021.111429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 05/09/2021] [Accepted: 05/26/2021] [Indexed: 01/12/2023]
Abstract
Cav3 channels play a critical role in maintaining calcium homeostasis, and its dysregulation is related to age-related diseases, such as age-related hearing loss (AHL). However, the underlying mechanism of the Cav3 channels involved in AHL remains unknown. Previous studies have shown that the degeneration of spiral ganglion neurons (SGNs) plays a critical role in AHL. Here, we explored the involvement of Cav3 channels in the dysregulation of SGNs in AHL. We used C57BL/6 mice as the AHL mouse model and found that the expression of Cav3 channels was increased in SGNs associated with age. The three subtypes of Cav3 channels were present in the apical, middle, and basal SGNs from young and older (AHL) mice. The immunostaining data suggest that Cav3.1 and Cav3.2 may contribute to Cav3 upregulation in SGNs of AHL mice. Additionally, we found that calpain-2 and apoptosis-inducing factor (AIF) were activated in SGNs from AHL mice. The inhibition of Cav3 channels or calpain-2 reduced AIF-activation in SGNs may affect neuronal survival. In conclusion, the findings suggest that Cav3 channels are upregulated in SGNs from AHL mice that may contribute to the degeneration of SGNs through the calpain-2-AIF apoptosis pathway in AHL mice.
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Affiliation(s)
- Qiaowei Geng
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050017, PR China; Center for Innovative Drug Research and Evaluation, Institute of Medical Science and Health, Hebei Medical University, Shijiazhuang, Hebei Province 050017, PR China
| | - Hongchen Li
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050017, PR China; Center for Innovative Drug Research and Evaluation, Institute of Medical Science and Health, Hebei Medical University, Shijiazhuang, Hebei Province 050017, PR China
| | - Haiwei Zhang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050017, PR China; Center for Innovative Drug Research and Evaluation, Institute of Medical Science and Health, Hebei Medical University, Shijiazhuang, Hebei Province 050017, PR China
| | - Mingshun Lu
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050017, PR China; Center for Innovative Drug Research and Evaluation, Institute of Medical Science and Health, Hebei Medical University, Shijiazhuang, Hebei Province 050017, PR China
| | - Jiaxi Liu
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050017, PR China; Center for Innovative Drug Research and Evaluation, Institute of Medical Science and Health, Hebei Medical University, Shijiazhuang, Hebei Province 050017, PR China
| | - Fei Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050017, PR China; Center for Innovative Drug Research and Evaluation, Institute of Medical Science and Health, Hebei Medical University, Shijiazhuang, Hebei Province 050017, PR China
| | - Haitao Shen
- Lab of Pathology, Hebei Medical University, Shijiazhuang, Hebei 050017, PR China
| | - Ebenezer N Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno, NV 89557, United States
| | - Zhanfeng Jia
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050017, PR China; Center for Innovative Drug Research and Evaluation, Institute of Medical Science and Health, Hebei Medical University, Shijiazhuang, Hebei Province 050017, PR China
| | - Ping Lv
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050017, PR China; Center for Innovative Drug Research and Evaluation, Institute of Medical Science and Health, Hebei Medical University, Shijiazhuang, Hebei Province 050017, PR China
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6
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Grandi FC, De Tomasi L, Mustapha M. Single-Cell RNA Analysis of Type I Spiral Ganglion Neurons Reveals a Lmx1a Population in the Cochlea. Front Mol Neurosci 2020; 13:83. [PMID: 32523514 PMCID: PMC7261882 DOI: 10.3389/fnmol.2020.00083] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 04/24/2020] [Indexed: 12/13/2022] Open
Abstract
In the mature cochlea, each inner hair cell (IHC) is innervated by multiple spiral ganglion neurons of type I (SGNI). SGNIs are morphologically and electro-physiologically diverse. Also, they differ in their susceptibility to noise insult. However, the molecular underpinnings of their identity and physiological differences remain poorly understood. In this study, we developed a novel triple transgenic mouse, which enabled the isolation of pure populations of SGNIs and the analysis of a 96-gene panel via single-cell qPCR. We found three distinct populations of Type I SGNs, which were marked by their exclusive expression of Lmx1a, Slc4a4, or Mfap4/Fzd2, respectively, at postnatal days P3, P8, and P12. Our data suggest that afferent SGN subtypes are established genetically before the onset of hearing and that the expression of key physiological markers, such as ion channels, is heterogeneous and may be underlying the heterogeneous firing proprieties of SGNIs.
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Affiliation(s)
| | - Lara De Tomasi
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom
| | - Mirna Mustapha
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom.,Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
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Lee JH, Kang M, Park S, Perez-Flores MC, Zhang XD, Wang W, Gratton MA, Chiamvimonvat N, Yamoah EN. The local translation of KNa in dendritic projections of auditory neurons and the roles of KNa in the transition from hidden to overt hearing loss. Aging (Albany NY) 2019; 11:11541-11564. [PMID: 31812952 PMCID: PMC6932877 DOI: 10.18632/aging.102553] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 11/20/2019] [Indexed: 02/07/2023]
Abstract
Local and privileged expression of dendritic proteins allows segregation of distinct functions in a single neuron but may represent one of the underlying mechanisms for early and insidious presentation of sensory neuropathy. Tangible characteristics of early hearing loss (HL) are defined in correlation with nascent hidden hearing loss (HHL) in humans and animal models. Despite the plethora of causes of HL, only two prevailing mechanisms for HHL have been identified, and in both cases, common structural deficits are implicated in inner hair cell synapses, and demyelination of the auditory nerve (AN). We uncovered that Na+-activated K+ (KNa) mRNA and channel proteins are distinctly and locally expressed in dendritic projections of primary ANs and genetic deletion of KNa channels (Kcnt1 and Kcnt2) results in the loss of proper AN synaptic function, characterized as HHL, without structural synaptic alterations. We further demonstrate that the local functional synaptic alterations transition from HHL to increased hearing-threshold, which entails changes in global Ca2+ homeostasis, activation of caspases 3/9, impaired regulation of inositol triphosphate receptor 1 (IP3R1), and apoptosis-mediated neurodegeneration. Thus, the present study demonstrates how local synaptic dysfunction results in an apparent latent pathological phenotype (HHL) and, if undetected, can lead to overt HL. It also highlights, for the first time, that HHL can precede structural synaptic dysfunction and AN demyelination. The stepwise cellular mechanisms from HHL to canonical HL are revealed, providing a platform for intervention to prevent lasting and irreversible age-related hearing loss (ARHL).
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Affiliation(s)
- Jeong Han Lee
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV 89557, USA
| | - Mincheol Kang
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV 89557, USA
| | - Seojin Park
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV 89557, USA
| | - Maria C Perez-Flores
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV 89557, USA
| | - Xiao-Dong Zhang
- Department of Internal Medicine, Division of Cardiology, University of California Davis, Davis, CA 95616, USA
| | - Wenying Wang
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV 89557, USA
| | - Michael Anne Gratton
- Department of Otolaryngology, Head and Neck Surgery, Washington University St. Louis, St. Louis, MO 63110, USA
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, Division of Cardiology, University of California Davis, Davis, CA 95616, USA
| | - Ebenezer N Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada Reno, Reno, NV 89557, USA
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Lundt A, Soós J, Seidel R, Henseler C, Müller R, Raj Ginde V, Imran Arshaad M, Ehninger D, Hescheler J, Sachinidis A, Broich K, Wormuth C, Papazoglou A, Weiergräber M. Functional implications of Ca v 2.3 R-type voltage-gated calcium channels in the murine auditory system - novel vistas from brainstem-evoked response audiometry. Eur J Neurosci 2019; 51:1583-1604. [PMID: 31603587 DOI: 10.1111/ejn.14591] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 09/11/2019] [Accepted: 10/08/2019] [Indexed: 12/25/2022]
Abstract
Voltage-gated Ca2+ channels (VGCCs) are considered to play a key role in auditory perception and information processing within the murine inner ear and brainstem. In the past, Cav 1.3 L-type VGCCs gathered most attention as their ablation causes congenital deafness. However, isolated patch-clamp investigation and localization studies repetitively suggested that Cav 2.3 R-type VGCCs are also expressed in the cochlea and further components of the ascending auditory tract, pointing to a potential functional role of Cav 2.3 in hearing physiology. Thus, we performed auditory profiling of Cav 2.3+/+ controls, heterozygous Cav 2.3+/- mice and Cav 2.3 null mutants (Cav 2.3-/- ) using brainstem-evoked response audiometry. Interestingly, click-evoked auditory brainstem responses (ABRs) revealed increased hearing thresholds in Cav 2.3+/- mice from both genders, whereas no alterations were observed in Cav 2.3-/- mice. Similar observations were made for tone burst-related ABRs in both genders. However, Cav 2.3 ablation seemed to prevent mutant mice from total hearing loss particularly in the higher frequency range (36-42 kHz). Amplitude growth function analysis revealed, i.a., significant reduction in ABR wave WI and WIII amplitude in mutant animals. In addition, alterations in WI -WIV interwave interval were observed in female Cav 2.3+/- mice whereas absolute latencies remained unchanged. In summary, our results demonstrate that Cav 2.3 VGCCs are mandatory for physiological auditory information processing in the ascending auditory tract.
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Affiliation(s)
- Andreas Lundt
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Bonn, Germany
| | - Julien Soós
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Bonn, Germany
| | - Robin Seidel
- Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Bonn, Germany
| | - Christina Henseler
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Bonn, Germany
| | - Ralf Müller
- Cognitive Neurophysiology, Department of Psychiatry and Psychotherapy and University Hospital Cologne, Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Varun Raj Ginde
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Bonn, Germany
| | - Muhammad Imran Arshaad
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Bonn, Germany
| | - Dan Ehninger
- Molecular and Cellular Cognition, German Center for Neurodegenerative Diseases, (Deutsches Zentrum für Neurodegenerative Erkrankungen, DZNE), Bonn, Germany
| | - Jürgen Hescheler
- Institute of Neurophysiology, Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Agapios Sachinidis
- Institute of Neurophysiology, Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Karl Broich
- Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Bonn, Germany
| | - Carola Wormuth
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Bonn, Germany
| | - Anna Papazoglou
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Bonn, Germany
| | - Marco Weiergräber
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Bonn, Germany
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Early functional alterations in membrane properties and neuronal degeneration are hallmarks of progressive hearing loss in NOD mice. Sci Rep 2019; 9:12128. [PMID: 31431657 PMCID: PMC6702171 DOI: 10.1038/s41598-019-48376-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 08/05/2019] [Indexed: 11/24/2022] Open
Abstract
Presbycusis or age-related hearing loss (ARHL) is the most common sensory deficit in the human population. A substantial component of the etiology stems from pathological changes in sensory and non-sensory cells in the cochlea. Using a non-obese diabetic (NOD) mouse model, we have characterized changes in both hair cells and spiral ganglion neurons that may be relevant for early signs of age-related hearing loss (ARHL). We demonstrate that hair cell loss is preceded by, or in parallel with altered primary auditory neuron functions, and latent neurite retraction at the hair cell-auditory neuron synapse. The results were observed first in afferent inner hair cell synapse of type I neurites, followed by type II neuronal cell-body degeneration. Reduced membrane excitability and loss of postsynaptic densities were some of the inaugural events before any outward manifestation of hair bundle disarray and hair cell loss. We have identified profound alterations in type I neuronal membrane properties, including a reduction in membrane input resistance, prolonged action potential latency, and a decrease in membrane excitability. The resting membrane potential of aging type I neurons in the NOD, ARHL model, was significantly hyperpolarized, and analyses of the underlying membrane conductance showed a significant increase in K+ currents. We propose that attempts to alleviate some forms of ARHL should include early targeted primary latent neural degeneration for effective positive outcomes.
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Stephani F, Scheuer V, Eckrich T, Blum K, Wang W, Obermair GJ, Engel J. Deletion of the Ca 2+ Channel Subunit α 2δ3 Differentially Affects Ca v2.1 and Ca v2.2 Currents in Cultured Spiral Ganglion Neurons Before and After the Onset of Hearing. Front Cell Neurosci 2019; 13:278. [PMID: 31293392 PMCID: PMC6606706 DOI: 10.3389/fncel.2019.00278] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 06/07/2019] [Indexed: 12/14/2022] Open
Abstract
Voltage-gated Ca2+ channels are composed of a pore-forming α1 subunit and auxiliary β and α2δ subunits, which modulate Ca2+ current properties and channel trafficking. So far, the partial redundancy and specificity of α1 for α2δ subunits in the CNS have remained largely elusive. Mature spiral ganglion (SG) neurons express α2δ subunit isoforms 1, 2, and 3 and multiple Ca2+ channel subtypes. Differentiation and in vivo functions of their endbulb of Held synapses, which rely on presynaptic P/Q channels (Lin et al., 2011), require the α2δ3 subunit (Pirone et al., 2014). This led us to hypothesize that P/Q channels may preferentially co-assemble with α2δ3. Using a dissociated primary culture, we analyzed the effects of α2δ3 deletion on somatic Ca2+ currents (ICa) of SG neurons isolated at postnatal day 20 (P20), when the cochlea is regarded to be mature. P/Q currents were the dominating steady-state Ca2+ currents (54% of total) followed by T-type, L-type, N-type, and R-type currents. Deletion of α2δ3 reduced P/Q- and R-type currents by 60 and 38%, respectively, whereas L-type, N-type, and T-type currents were not altered. A subset of ICa types was also analyzed in SG neurons isolated at P5, i.e., before the onset of hearing (P12). Both L-type and N-type current amplitudes of wildtype SG neurons were larger at P5 compared with P20. Deletion of α2δ3 reduced L-type and N-type currents by 23 and 44%, respectively. In contrast, small P/Q currents, which were just being up-regulated at P5, were unaffected by the lack of α2δ3. In summary, α2δ3 regulates amplitudes of L- and N-type currents of immature cultured SG neurons, whereas it regulates P/Q- and R-type currents at P20. Our data indicate a developmental switch from dominating somatic N- to P/Q-type currents in cultured SG neurons. A switch from N- to P/Q-type channels, which has been observed at several central synapses, may also occur at developing endbulbs of Held. In this case, reduction of both neonatal N- (P5) and more mature P/Q-type currents (around/after hearing onset) may contribute to the impaired morphology and function of endbulb synapses in α2δ3-deficient mice.
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Affiliation(s)
- Friederike Stephani
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - Veronika Scheuer
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - Tobias Eckrich
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - Kerstin Blum
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
| | - Wenying Wang
- Department of Physiology, School of Medicine, University of Nevada, Reno, NV, United States
| | - Gerald J Obermair
- Department of Physiology and Medical Physics, Medical University Innsbruck, Innsbruck, Austria.,Division Physiology, Karl Landsteiner University of Health Sciences, Krems, Austria
| | - Jutta Engel
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg, Germany
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11
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Sodium-activated potassium channels shape peripheral auditory function and activity of the primary auditory neurons in mice. Sci Rep 2019; 9:2573. [PMID: 30796290 PMCID: PMC6384918 DOI: 10.1038/s41598-019-39119-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/17/2019] [Indexed: 11/08/2022] Open
Abstract
Potassium (K+) channels shape the response properties of neurons. Although enormous progress has been made to characterize K+ channels in the primary auditory neurons, the molecular identities of many of these channels and their contributions to hearing in vivo remain unknown. Using a combination of RNA sequencing and single molecule fluorescent in situ hybridization, we localized expression of transcripts encoding the sodium-activated potassium channels KNa1.1 (SLO2.2/Slack) and KNa1.2 (SLO2.1/Slick) to the primary auditory neurons (spiral ganglion neurons, SGNs). To examine the contribution of these channels to function of the SGNs in vivo, we measured auditory brainstem responses in KNa1.1/1.2 double knockout (DKO) mice. Although auditory brainstem response (wave I) thresholds were not altered, the amplitudes of suprathreshold responses were reduced in DKO mice. This reduction in amplitude occurred despite normal numbers and molecular architecture of the SGNs and their synapses with the inner hair cells. Patch clamp electrophysiology of SGNs isolated from DKO mice displayed altered membrane properties, including reduced action potential thresholds and amplitudes. These findings show that KNa1 channel activity is essential for normal cochlear function and suggest that early forms of hearing loss may result from physiological changes in the activity of the primary auditory neurons.
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12
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Wong VSC, Meadows M, Goldberg D, Willis DE. Semaphorin 3A induces acute changes in membrane excitability in spiral ganglion neurons in vitro. Eur J Neurosci 2019; 50:1741-1758. [PMID: 30706560 DOI: 10.1111/ejn.14360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 01/10/2019] [Accepted: 01/23/2019] [Indexed: 11/29/2022]
Abstract
The development and survival of spiral ganglion neurons (SGNs) are dependent on multiple trophic factors as well as membrane electrical activity. Semaphorins (Sema) constitute a family of membrane-associated and secreted proteins that have garnered significant attention as a potential SGN "navigator" during cochlea development. Previous studies using mutant mice demonstrated that Sema3A plays a role in the SGN pathfinding. The mechanisms, however, by which Sema3A shapes SGNs firing behavior are not known. In these studies, we found that Sema3A plays a novel role in regulating SGN resting membrane potential and excitability. Using dissociated SGN from pre-hearing (P3-P5) and post-hearing mice (P12-P15), we recorded membrane potentials using whole-cell patch clamp recording techniques in apical and basal SGN populations. Recombinant Sema3A was applied to examine the effects on intrinsic membrane properties and action potentials evoked by current injections. Apical and basal SGNs from newborn mice treated with recombinant Sema3A (100 ng/ml) displayed a higher resting membrane potential, higher threshold, decreased amplitude, and prolonged latency and duration of spikes. Although a similar phenomenon was observed in SGNs from post-hearing mice, the resting membrane potential was essentially indistinguishable before and after Sema3A exposure. Sema3A-mediated changes in membrane excitability were associated with a significant decrease in K+ and Ca2+ currents. Sema3A acts through linopirdine-sensitive K+ channels in apical, but not in the basal SGNs. Therefore, Sema3A induces differential effects in SGN membrane excitability that are dependent on age and location, and constitutes an additional early and novel effect of Sema3A SGNs in vitro.
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Affiliation(s)
| | - Marc Meadows
- The Vollum Institute, Oregon Health and Science University, Portland, Oregon
| | - David Goldberg
- The Burke Neurological Institute, White Plains, New York
| | - Dianna E Willis
- The Burke Neurological Institute, White Plains, New York.,Brain and Mind Research Institute, Weill Cornell Medicine, New York, New York
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13
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Yu Y, Hu B, Bao J, Mulvany J, Bielefeld E, Harrison RT, Neton SA, Thirumala P, Chen Y, Lei D, Qiu Z, Zheng Q, Ren J, Perez-Flores MC, Yamoah EN, Salehi P. Otoprotective Effects of Stephania tetrandra S. Moore Herb Isolate against Acoustic Trauma. J Assoc Res Otolaryngol 2018; 19:653-668. [PMID: 30187298 PMCID: PMC6249158 DOI: 10.1007/s10162-018-00690-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 07/08/2018] [Indexed: 01/10/2023] Open
Abstract
Noise is the most common occupational and environmental hazard, and noise-induced hearing loss (NIHL) is the second most common form of sensorineural hearing deficit. Although therapeutics that target the free-radical pathway have shown promise, none of these compounds is currently approved against NIHL by the United States Food and Drug Administration. The present study has demonstrated that tetrandrine (TET), a traditional Chinese medicinal alkaloid and the main chemical isolate of the Stephania tetrandra S. Moore herb, significantly attenuated NIHL in CBA/CaJ mice. TET is known to exert antihypertensive and antiarrhythmic effects through the blocking of calcium channels. Whole-cell patch-clamp recording from adult spiral ganglion neurons showed that TET blocked the transient Ca2+ current in a dose-dependent manner and the half-blocking concentration was 0.6 + 0.1 μM. Consistent with previous findings that modulations of calcium-based signaling pathways have both prophylactic and therapeutic effects against neural trauma, NIHL was significantly diminished by TET administration. Importantly, TET has a long-lasting protective effect after noise exposure (48 weeks) in comparison to 2 weeks after noise exposure. The otoprotective effects of TET were achieved mainly by preventing outer hair cell damage and synapse loss between inner hair cells and spiral ganglion neurons. Thus, our data indicate that TET has great potential in the prevention and treatment of NIHL.
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Affiliation(s)
- Yan Yu
- The First People’s Hospital of Zhangjiagang, 68 W Jiyang Road, Zhangjiagang City, 215600 Jiangsu China
- Translational Research Center, Northeast Ohio Medical University, Rootstown, OH 44272 USA
| | - Bing Hu
- Translational Research Center, Northeast Ohio Medical University, Rootstown, OH 44272 USA
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, OH 44106 USA
- Department of Otolaryngology Head and Neck Surgery, The Second Xiangya Hospital of Central South University, Changsha, 440011 Hunan China
| | - Jianxin Bao
- Translational Research Center, Northeast Ohio Medical University, Rootstown, OH 44272 USA
- Department of Research and Development, Gateway Biotechnology Inc., Rootstown, OH 44272 USA
| | - Jessica Mulvany
- Translational Research Center, Northeast Ohio Medical University, Rootstown, OH 44272 USA
- Department of Research and Development, Gateway Biotechnology Inc., Rootstown, OH 44272 USA
| | - Eric Bielefeld
- Department of Speech and Hearing Science, Ohio State University, Columbus, OH 43210 USA
| | - Ryan T. Harrison
- Department of Speech and Hearing Science, Ohio State University, Columbus, OH 43210 USA
| | - Sarah A. Neton
- Department of Speech and Hearing Science, Ohio State University, Columbus, OH 43210 USA
| | - Partha Thirumala
- The University of Pittsburgh Medical Center, Suite B-400, 200 Lothrop Street, Pittsburgh, PA 15213 USA
| | - Yingying Chen
- Translational Research Center, Northeast Ohio Medical University, Rootstown, OH 44272 USA
| | - Debin Lei
- Translational Research Center, Northeast Ohio Medical University, Rootstown, OH 44272 USA
| | - Ziyu Qiu
- Department of Research and Development, Gateway Biotechnology Inc., Rootstown, OH 44272 USA
| | - Qingyin Zheng
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, OH 44106 USA
| | - Jihao Ren
- Department of Otolaryngology Head and Neck Surgery, The Second Xiangya Hospital of Central South University, Changsha, 440011 Hunan China
| | - Maria Cristina Perez-Flores
- Department of Physiology and Cell Biology, University of Nevada Reno, 1664 North Virginia St, Reno, NV 89557 USA
| | - Ebenezer N. Yamoah
- Department of Physiology and Cell Biology, University of Nevada Reno, 1664 North Virginia St, Reno, NV 89557 USA
| | - Pezhman Salehi
- Translational Research Center, Northeast Ohio Medical University, Rootstown, OH 44272 USA
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14
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Localizing Proton-Mediated Inhibitory Feedback at the Retinal Horizontal Cell-Cone Synapse with Genetically-Encoded pH Probes. J Neurosci 2018; 39:651-662. [PMID: 30504272 DOI: 10.1523/jneurosci.1541-18.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 11/12/2018] [Accepted: 11/17/2018] [Indexed: 11/21/2022] Open
Abstract
Lateral inhibition in the vertebrate retina depends on a negative feedback synapse between horizontal cells (HCs) and rod and cone photoreceptors. A change in pH is thought to be the signal for negative feedback, but its spatial profile in the synaptic cleft is unknown. Here we use three different membrane proteins, each fused to the same genetically-encoded pH-sensitive Green Fluorescent Protein (GFP) (pHluorin), to probe synaptic pH in retina from transgenic zebrafish (Danio rerio) of either sex. We used the cone transducin promoter to express SynaptopHluorin (pHluorin on vesicle-associated membrane protein (VAMP2)) or CalipHluorin (pHluorin on an L-type Ca2+ channel) and the HC-specific connexin-55.5 promoter to express AMPApHluorin (pHluorin on an AMPA receptor). Stimulus light led to increased fluorescence of all three probes, consistent with alkalinization of the synaptic cleft. The receptive field size, sensitivity to surround illumination, and response to activation of an alien receptor expressed exclusively in HCs, are consistent with lateral inhibition as the trigger for alkalinization. However, SynaptopHluorin and AMPApHluorin, which are displaced farther from cone synaptic ribbons than CalipHluorin, reported a smaller pH change. Hence, unlike feedforward glutamatergic transmission, which spills over to allow cross talk between terminals in the cone network, the pH change underlying HC feedback is compartmentalized to individual synaptic invaginations within a cone terminal, consistent with private line communication.SIGNIFICANCE STATEMENT Lateral inhibition (LI) is a fundamental feature of information processing in sensory systems, enhancing contrast sensitivity and enabling edge discrimination. Horizontal cells (HCs) are the first cellular substrate of LI in the vertebrate retina, but the synaptic mechanisms underlying LI are not completely understood, despite decades of study. This paper makes a significant contribution to our understanding of LI, by showing that each HC-cone synapse is a "private-line" that operates independently from other HC-cone connections. Using transgenic zebrafish expressing pHluorin, a pH-sensitive GFP variant spliced onto three different protein platforms expressed either in cones or HCs we show that the feedback pH signal is constrained to individual cone terminals, and more stringently, to individual synaptic contact sites within each terminal.
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15
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Shen H, Liu W, Geng Q, Li H, Lu M, Liang P, Zhang B, Yamoah EN, Lv P. Age-Dependent Up-Regulation of HCN Channels in Spiral Ganglion Neurons Coincide With Hearing Loss in Mice. Front Aging Neurosci 2018; 10:353. [PMID: 30459593 PMCID: PMC6232381 DOI: 10.3389/fnagi.2018.00353] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/17/2018] [Indexed: 01/05/2023] Open
Abstract
Age-related hearing loss (AHL) is the most common sensory disorder in the elderly population, and the etiologies are diverse. To understand the underlying mechanisms of AHL, one strategy is to identify correlates of the disease for comprehensive evaluation of treatment approaches. Dysfunction and degeneration of spiral ganglion neurons (SGNs) are major contributors to AHL. Previously, we showed that one of the changes in the aging auditory system is SGN excitability increase in mice. Since hyperpolarization-activated cyclic nucleotide-gated (HCN) channels play important roles in determining neuronal excitability, we predicted that HCN channels in SGNs are involved in AHL. To investigate the contribution of HCN channels to AHL, we examined the expression and biophysical properties of HCN channels in SGNs from adult (2–3 months) and 11–12-month-old mice. We report a dramatic increase of HCN channel current (Ih) in SGNs in old mice (11–12 months old). The results matched well with increased expression of HCN1 and HCN2 subunits, suggesting that upregulation of HCN channels in SGNs is one of the important facets of the aging SGNs. Moreover, the activity of Ih produced a major impact on the firing properties of SGNs in older mice. The upregulation of Ih may contribute to AHL by regulating SGN excitability. We assessed whether increased SGNs excitability dovetail with neurodegeneration. Apoptosis-inducing factor (AIF)-mediated apoptosis in SGNs was observed in old mice and activation of HCN channels mediates AIF activation. Thus, these findings demonstrate stark correlation between age-dependent increased expression of HCN channels and Ih, and apoptosis in SGNs, which may contribute towards the varied mechanisms of AHL.
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Affiliation(s)
- Haitao Shen
- Laboratory of Pathology, Hebei Medical University, Shijiazhuang, China
| | - Weilin Liu
- Division of Cardiovascular Medicine, Hebei Province Geriatric Hospital, Shijiazhuang, China
| | - Qiaowei Geng
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Hongchen Li
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Mingshun Lu
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Peng Liang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Bo Zhang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Ebenezer N Yamoah
- Department of Physiology, School of Medicine, University of Nevada, Reno, NV, United States
| | - Ping Lv
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
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16
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Detection of single mRNAs in individual cells of the auditory system. Hear Res 2018; 367:88-96. [PMID: 30071403 DOI: 10.1016/j.heares.2018.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 05/23/2018] [Accepted: 07/16/2018] [Indexed: 01/17/2023]
Abstract
Gene expression analysis is essential for understanding the rich repertoire of cellular functions. With the development of sensitive molecular tools such as single-cell RNA sequencing, extensive gene expression data can be obtained and analyzed from various tissues. Single-molecule fluorescence in situ hybridization (smFISH) has emerged as a powerful complementary tool for single-cell genomics studies because of its ability to map and quantify the spatial distributions of single mRNAs at the subcellular level in their native tissue. Here, we present a detailed method to study the copy numbers and spatial localizations of single mRNAs in the cochlea and inferior colliculus. First, we demonstrate that smFISH can be performed successfully in adult cochlear tissue after decalcification. Second, we show that the smFISH signals can be detected with high specificity. Third, we adapt an automated transcript analysis pipeline to quantify and identify single mRNAs in a cell-specific manner. Lastly, we show that our method can be used to study possible correlations between transcriptional and translational activities of single genes. Thus, we have developed a detailed smFISH protocol that can be used to study the expression of single mRNAs in specific cell types of the peripheral and central auditory systems.
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17
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Yang T, Hu N, Pangršič T, Green S, Hansen M, Lee A. Functions of CaBP1 and CaBP2 in the peripheral auditory system. Hear Res 2018; 364:48-58. [PMID: 29661613 DOI: 10.1016/j.heares.2018.04.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/13/2018] [Accepted: 04/02/2018] [Indexed: 12/29/2022]
Abstract
CaBPs are a family of Ca2+ binding proteins related to calmodulin. Two CaBP family members, CaBP1 and CaBP2, are highly expressed in the cochlea. Here, we investigated the significance of CaBP1 and CaBP2 for hearing in mice lacking expression of these proteins (CaBP1 KO and CaBP2 KO) using auditory brain responses (ABRs) and distortion product otoacoustic emissions (DPOAEs). In CaBP1 KO mice, ABR wave I was larger in amplitude, and shorter in latency and faster in decay, suggestive of enhanced synchrony of auditory nerve fibers. This interpretation was supported by the greater excitability of CaBP1 KO than WT neurons in whole-cell patch clamp recordings of spiral ganglion neurons in culture, and normal presynaptic function of CaBP1 KO IHCs. DPOAEs and ABR thresholds were normal in 4-week old CaBP1 KO mice, but elevated ABR thresholds became evident at 32 kHz at 9 weeks, and at 8 and 16 kHz by 6 months of age. In contrast, CaBP2 KO mice exhibited significant ABR threshold elevations at 4 weeks of age that became more severe in the mid-frequency range by 9 weeks. Though normal at 4 weeks, DPOAEs in CaBP2 KO mice were significantly reduced in the mid-frequency range by 9 weeks. Our results reveal requirements for CaBP1 and CaBP2 in the peripheral auditory system and highlight the diverse modes by which CaBPs influence sensory processing.
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Affiliation(s)
- Tian Yang
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA; Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - Ning Hu
- Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA 52242, USA; Department of Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Tina Pangršič
- Synaptic Physiology of Mammalian Vestibular Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Steven Green
- Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA 52242, USA; Department of Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Marlan Hansen
- Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA 52242, USA; Department of Neurosurgery, University of Iowa, Iowa City, IA 52242, USA
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA; Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA 52242, USA; Department of Neurology, University of Iowa, Iowa City, IA 52242, USA.
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18
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Yang T, Choi JE, Soh D, Tobin K, Joiner ML, Hansen M, Lee A. CaBP1 regulates Ca v1 L-type Ca 2+ channels and their coupling to neurite growth and gene transcription in mouse spiral ganglion neurons. Mol Cell Neurosci 2018; 88:342-352. [PMID: 29548764 DOI: 10.1016/j.mcn.2018.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 03/07/2018] [Accepted: 03/12/2018] [Indexed: 12/19/2022] Open
Abstract
CaBP1 is a Ca2+ binding protein that is widely expressed in neurons in the brain, retina, and cochlea. In heterologous expression systems, CaBP1 interacts with and regulates voltage-gated Cav Ca2+ channels but whether this is the case in neurons is unknown. Here, we investigated the cellular functions of CaBP1 in cochlear spiral ganglion neurons (SGNs), which express high levels of CaBP1. Consistent with the role of CaBP1 as a suppressor of Ca2+-dependent inactivation (CDI) of Cav1 (L-type) channels, Cav1 currents underwent greater CDI in SGNs from mice lacking CaBP1 (C-KO) than in wild-type (WT) SGNs. The coupling of Cav1 channels to downstream signaling pathways was also disrupted in C-KO SGNs. Activity-dependent repression of neurite growth was significantly blunted and unresponsive to Cav1 antagonists in C-KO SGNs in contrast to WT SGNs. Moreover, Cav1-mediated Ca2+ signals and phosphorylation of cAMP-response element binding protein were reduced in C-KO SGNs compared to WT SGNs. Our findings establish a role for CaBP1 as an essential regulator of Cav1 channels in SGNs and their coupling to downstream pathways controlling activity-dependent transcription and neurite growth.
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Affiliation(s)
- Tian Yang
- Departments of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA
| | - Ji-Eun Choi
- Departments of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA
| | - Daniel Soh
- Departments of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA
| | - Kevin Tobin
- Departments of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA
| | - Mei-Ling Joiner
- Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - Marlan Hansen
- Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA 52242, USA; Neurosurgery, University of Iowa, Iowa City, IA 52242, USA
| | - Amy Lee
- Departments of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA; Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA 52242, USA; Neurology, University of Iowa, Iowa City, IA 52242, USA.
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19
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Time-dependent activity of primary auditory neurons in the presence of neurotrophins and antibiotics. Hear Res 2017; 350:122-132. [DOI: 10.1016/j.heares.2017.04.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 03/16/2017] [Accepted: 04/23/2017] [Indexed: 12/19/2022]
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20
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Reijntjes DO, Pyott SJ. The afferent signaling complex: Regulation of type I spiral ganglion neuron responses in the auditory periphery. Hear Res 2016; 336:1-16. [DOI: 10.1016/j.heares.2016.03.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 02/12/2016] [Accepted: 03/07/2016] [Indexed: 12/19/2022]
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21
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Alvarado JC, Fuentes-Santamaría V, Gabaldón-Ull MC, Jareño-Flores T, Miller JM, Juiz JM. Noise-Induced "Toughening" Effect in Wistar Rats: Enhanced Auditory Brainstem Responses Are Related to Calretinin and Nitric Oxide Synthase Upregulation. Front Neuroanat 2016; 10:19. [PMID: 27065815 PMCID: PMC4815363 DOI: 10.3389/fnana.2016.00019] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 02/15/2016] [Indexed: 01/07/2023] Open
Abstract
An appropriate conditioning noise exposure may reduce a subsequent noise-induced threshold shift. Although this "toughening" effect helps to protect the auditory system from a subsequent traumatic noise exposure, the mechanisms that regulate this protective process are not fully understood yet. Accordingly, the goal of the present study was to characterize physiological processes associated with "toughening" and to determine their relationship to metabolic changes in the cochlea and cochlear nucleus (CN). Auditory brainstem responses (ABR) were evaluated in Wistar rats before and after exposures to a sound conditioning protocol consisting of a broad-band white noise of 118 dB SPL for 1 h every 72 h, four times. After the last ABR evaluation, animals were perfused and their cochleae and brains removed and processed for the activity markers calretinin (CR) and neuronal nitric oxide synthase (nNOS). Toughening was demonstrated by a progressively faster recovery of the threshold shift, as well as wave amplitudes and latencies over time. Immunostaining revealed an increase in CR and nNOS levels in the spiral ganglion, spiral ligament, and CN in noise-conditioned rats. Overall, these results suggest that the protective mechanisms of the auditory toughening effect initiate in the cochlea and extend to the central auditory system. Such phenomenon might be in part related to an interplay between CR and nitric oxide signaling pathways, and involve an increased cytosolic calcium buffering capacity induced by the noise conditioning protocol.
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Affiliation(s)
- Juan C Alvarado
- Instituto de Investigación en Discapacidades NeurológicasAlbacete, Spain; Facultad de Medicina, Universidad de Castilla-La ManchaAlbacete, Spain
| | - Verónica Fuentes-Santamaría
- Instituto de Investigación en Discapacidades NeurológicasAlbacete, Spain; Facultad de Medicina, Universidad de Castilla-La ManchaAlbacete, Spain
| | - María C Gabaldón-Ull
- Instituto de Investigación en Discapacidades NeurológicasAlbacete, Spain; Facultad de Medicina, Universidad de Castilla-La ManchaAlbacete, Spain
| | - Tania Jareño-Flores
- Grupo de Neurobiología de la Audición, Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid Madrid, Spain
| | - Josef M Miller
- Center for Hearing and Communication Research and Department of Clinical Neuroscience, Karolinska InstitutetStockholm, Sweden; Kresge Hearing Research Institute, University of MichiganAnn Arbor, MI, USA
| | - José M Juiz
- Instituto de Investigación en Discapacidades NeurológicasAlbacete, Spain; Facultad de Medicina, Universidad de Castilla-La ManchaAlbacete, Spain
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22
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Phosphoinositide Modulation of Heteromeric Kv1 Channels Adjusts Output of Spiral Ganglion Neurons from Hearing Mice. J Neurosci 2015; 35:11221-32. [PMID: 26269632 DOI: 10.1523/jneurosci.0496-15.2015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
UNLABELLED Spiral ganglion neurons (SGNs) relay acoustic code from cochlear hair cells to the brainstem, and their stimulation enables electrical hearing via cochlear implants. Rapid adaptation, a mechanism that preserves temporal precision, and a prominent feature of auditory neurons, is regulated via dendrotoxin-sensitive low-threshold voltage-activated (LVA) K(+) channels. Here, we investigated the molecular physiology of LVA currents in SGNs cultured from mice following the onset of hearing (postnatal days 12-21). Kv1.1- and Kv1.2-specific toxins blocked the LVA currents in a comparable manner, suggesting that both subunits contribute to functional heteromeric channels. Confocal immunofluorescence in fixed cochlear sections localized both Kv1.1 and Kv1.2 subunits to specific neuronal microdomains, including the somatic membrane, juxtaparanodes, and the first heminode, which forms the spike initiation site of the auditory nerve. The spatial distribution of Kv1 immunofluorescence appeared mutually exclusive to that of Kv3.1b subunits, which mediate high-threshold voltage-activated currents. As Kv1.2-containing channels are positively modulated by membrane phosphoinositides, we investigated the influence of phosphatidylinositol-4,5-bisphosphate (PIP2) availability on SGN electrophysiology. Reducing PIP2 production using wortmannin, or sequestration of PIP2 using a palmitoylated peptide (PIP2-PP), slowed adaptation rate in SGN populations. PIP2-PP specifically inhibited the LVA current in SGNs, an effect reduced by intracellular dialysis of a nonhydrolysable analog of PIP2. PIP2-PP also inhibited heterologously expressed Kv1.1/Kv1.2 channels, recapitulating its effect in SGNs. Collectively, the data identify Kv1.1/Kv1.2 heteromeric channels as key regulators of action potential initiation and propagation in the auditory nerve, and suggest that modulation of these channels by endogenous phosphoinositides provides local control of membrane excitability. SIGNIFICANCE STATEMENT Rapid spike adaptation is an important feature of auditory neurons that preserves temporal precision. In spiral ganglion neurons, the primary afferents in the cochlea, adaptation is regulated by heteromeric ion channels composed of Kv1.1 and Kv1.2 subunits. These subunits colocalize to common functional microdomains, such as juxtaparanodes and the somatic membrane. Activity of the heteromeric channels is controlled by cellular availability of PIP2, a membrane phospholipid. This mechanism provides an intrinsic regulation of output from the auditory nerve, which could be targeted for therapeutic adjustment of hearing sensitivity.
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Zhang XD, Lee JH, Lv P, Chen WC, Kim HJ, Wei D, Wang W, Sihn CR, Doyle KJ, Rock JR, Chiamvimonvat N, Yamoah EN. Etiology of distinct membrane excitability in pre- and posthearing auditory neurons relies on activity of Cl- channel TMEM16A. Proc Natl Acad Sci U S A 2015; 112:2575-80. [PMID: 25675481 PMCID: PMC4345570 DOI: 10.1073/pnas.1414741112] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The developmental rehearsal for the debut of hearing is marked by massive changes in the membrane properties of hair cells (HCs) and spiral ganglion neurons (SGNs). Whereas the underlying mechanisms for the developing HC transition to mature stage are understood in detail, the maturation of SGNs from hyperexcitable prehearing to quiescent posthearing neurons with broad dynamic range is unknown. Here, we demonstrated using pharmacological approaches, caged-Ca(2+) photolysis, and gramicidin patch recordings that the prehearing SGN uses Ca(2+)-activated Cl(-) conductance to depolarize the resting membrane potential and to prime the neurons in a hyperexcitable state. Immunostaining of the cochlea preparation revealed the identity and expression of the Ca(2+)-activated Cl(-) channel transmembrane member 16A (TMEM16A) in SGNs. Moreover, null deletion of TMEM16A reduced the Ca(2+)-activated Cl(-) currents and action potential firing in SGNs. To determine whether Cl(-) ions and TMEM16A are involved in the transition between pre- and posthearing features of SGNs we measured the intracellular Cl(-) concentration [Cl(-)]i in SGNs. Surprisingly, [Cl(-)]i in SGNs from prehearing mice was ∼90 mM, which was significantly higher than posthearing neurons, ∼20 mM, demonstrating discernible altered roles of Cl(-) channels in the developing neuron. The switch in [Cl(-)]i stems from delayed expression of the development of intracellular Cl(-) regulating mechanisms. Because the Cl(-) channel is the only active ion-selective conductance with a reversal potential that lies within the dynamic range of SGN action potentials, developmental alteration of [Cl(-)]i, and hence the equilibrium potential for Cl(-) (ECl), transforms pre- to posthearing phenotype.
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Affiliation(s)
- Xiao-Dong Zhang
- Department of Internal Medicine, Division of Cardiovascular Medicine, School of Medicine, University of California, Davis, CA 95616
| | - Jeong-Han Lee
- Program in Communication Science, Department of Physiology, School of Medicine, University of Nevada, Reno, Reno NV 89557
| | - Ping Lv
- Program in Communication Science, Department of Physiology, School of Medicine, University of Nevada, Reno, Reno NV 89557; Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China
| | - Wei Chun Chen
- Program in Communication Science, Department of Physiology, School of Medicine, University of Nevada, Reno, Reno NV 89557
| | - Hyo Jeong Kim
- Program in Communication Science, Department of Physiology, School of Medicine, University of Nevada, Reno, Reno NV 89557
| | - Dongguang Wei
- Program in Communication Science, Department of Physiology, School of Medicine, University of Nevada, Reno, Reno NV 89557
| | - Wenying Wang
- Program in Communication Science, Department of Physiology, School of Medicine, University of Nevada, Reno, Reno NV 89557
| | - Choong-Ryoul Sihn
- Program in Communication Science, Department of Physiology, School of Medicine, University of Nevada, Reno, Reno NV 89557
| | - Karen Jo Doyle
- Program in Communication Science, Department of Physiology, School of Medicine, University of Nevada, Reno, Reno NV 89557
| | - Jason R Rock
- Department of Anatomy, School of Medicine, University of California, San Francisco, CA 94143; and
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, Division of Cardiovascular Medicine, School of Medicine, University of California, Davis, CA 95616; Department of Veterans Affairs, Northern California Health Care System, Mather, CA 95655
| | - Ebenezer N Yamoah
- Program in Communication Science, Department of Physiology, School of Medicine, University of Nevada, Reno, Reno NV 89557;
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24
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Davis RL, Crozier RA. Dynamic firing properties of type I spiral ganglion neurons. Cell Tissue Res 2015; 361:115-27. [PMID: 25567109 DOI: 10.1007/s00441-014-2071-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 11/17/2014] [Indexed: 10/24/2022]
Abstract
Spiral ganglion neurons, the first neural element in the auditory system, possess complex intrinsic properties, possibly required to process frequency-specific sensory input that is integrated with extensive efferent regulation. Together with their tonotopically-graded sizes, the somata of these neurons reveal a sophisticated electrophysiological profile. Type I neurons, which make up ~95 % of the ganglion, have myriad voltage-gated ion channels that not only vary along the frequency contour of the cochlea, but also can be modulated by regulators such as voltage, calcium, and second messengers. The resultant developmentally- and tonotopically-regulated neuronal firing patterns conform to three distinct response modes (unitary, rapid, and slow) based on threshold and accommodation. This phenotype, however, is not static for any individual type I neuron. Recent observations have shown that, as neurons become less excitable with age, they demonstrate enhanced plasticity enabling them to change from one response mode to another depending upon resting membrane potential and the presence of neurotrophin-3. Thus, the primary auditory afferents utilized to encode dynamic acoustic stimuli possess the intrinsic specializations that allow them dynamically to alter their firing pattern.
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Affiliation(s)
- Robin L Davis
- Department of Cell Biology and Neuroscience, Nelson Laboratories, Rutgers University, 604 Allison Road, Piscataway, NJ 08854, USA,
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25
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Crozier RA, Davis RL. Unmasking of spiral ganglion neuron firing dynamics by membrane potential and neurotrophin-3. J Neurosci 2014; 34:9688-702. [PMID: 25031408 PMCID: PMC4099546 DOI: 10.1523/jneurosci.4552-13.2014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 05/25/2014] [Accepted: 06/13/2014] [Indexed: 02/06/2023] Open
Abstract
Type I spiral ganglion neurons have a unique role relative to other sensory afferents because, as a single population, they must convey the richness, complexity, and precision of auditory information as they shape signals transmitted to the brain. To understand better the sophistication of spiral ganglion response properties, we compared somatic whole-cell current-clamp recordings from basal and apical neurons obtained during the first 2 postnatal weeks from CBA/CaJ mice. We found that during this developmental time period neuron response properties changed from uniformly excitable to differentially plastic. Low-frequency, apical and high-frequency basal neurons at postnatal day 1 (P1)-P3 were predominantly slowly accommodating (SA), firing at low thresholds with little alteration in accommodation response mode induced by changes in resting membrane potential (RMP) or added neurotrophin-3 (NT-3). In contrast, P10-P14 apical and basal neurons were predominately rapidly accommodating (RA), had higher firing thresholds, and responded to elevation of RMP and added NT-3 by transitioning to the SA category without affecting the instantaneous firing rate. Therefore, older neurons appeared to be uniformly less excitable under baseline conditions yet displayed a previously unrecognized capacity to change response modes dynamically within a remarkably stable accommodation framework. Because the soma is interposed in the signal conduction pathway, these specializations can potentially lead to shaping and filtering of the transmitted signal. These results suggest that spiral ganglion neurons possess electrophysiological mechanisms that enable them to adapt their response properties to the characteristics of incoming stimuli and thus have the capacity to encode a wide spectrum of auditory information.
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Affiliation(s)
- Robert A Crozier
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
| | - Robin L Davis
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
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26
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Genetic, cellular, and functional evidence for Ca2+ inflow through Cav1.2 and Cav1.3 channels in murine spiral ganglion neurons. J Neurosci 2014; 34:7383-93. [PMID: 24849370 DOI: 10.1523/jneurosci.5416-13.2014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Spiral ganglion neurons (SGNs) of the eighth nerve serve as the bridge between hair cells and the cochlear nucleus. Hair cells use Cav1.3 as the primary channel for Ca(2+) inflow to mediate transmitter release. In contrast, SGNs are equipped with multiple Ca(2+) channels to mediate Ca(2+)-dependent functions. We examined directly the role of Cav1.3 channels in SGNs using Cav1.3-deficient mice (Cav1.3(-/-)). We revealed a surprising finding that SGNs functionally express the cardiac-specific Cav1.2, as well as neuronal Cav1.3 channels. We show that evoked action potentials recorded from SGNs show a significant decrease in the frequency of firing in Cav1.3(-/-) mice compared with wild-type (Cav1.3(+/+)) littermates. Although Cav1.3 is the designated L-type channel in neurons, whole-cell currents recorded in isolated SGNs from Cav1.3(-/-) mice showed a surprising remnant current with sensitivity toward the dihydropyridine (DHP) agonist and antagonist, and a depolarization shift in the voltage-dependent activation compared with that in the Cav1.3(+/+) mice. Indeed, direct measurement of the elementary properties of Ca(2+) channels, in Cav1.3(+/+) neurons, confirmed the existence of two DHP-sensitive single-channel currents, with distinct open probabilities and conductances. We demonstrate that the DHP-sensitive current in Cav1.3(-/-) mice is derived from Cav1.2 channel activity, providing for the first time, to our knowledge, functional data for the expression of Cav1.2 currents in neurons. Finally, using shRNA gene knockdown methodology, and histological analyses of SGNs from Cav1.2(+/-) and Cav1.3(+/-) mice, we were able to establish the differential roles of Cav1.2 and Cav1.3 in SGNs.
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27
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Kim YH, Holt JR. Functional contributions of HCN channels in the primary auditory neurons of the mouse inner ear. ACTA ACUST UNITED AC 2014; 142:207-23. [PMID: 23980193 PMCID: PMC3753603 DOI: 10.1085/jgp.201311019] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The hyperpolarization-activated current, Ih, is carried by members of the Hcn channel family and contributes to resting potential and firing properties in excitable cells of various systems, including the auditory system. Ih has been identified in spiral ganglion neurons (SGNs); however, its molecular correlates and their functional contributions have not been well characterized. To investigate the molecular composition of the channels that carry Ih in SGNs, we examined Hcn mRNA harvested from spiral ganglia of neonatal and adult mice using quantitative RT-PCR. The data indicate expression of Hcn1, Hcn2, and Hcn4 subunits in SGNs, with Hcn1 being the most highly expressed at both stages. To investigate the functional contributions of HCN subunits, we used the whole-cell, tight-seal technique to record from wild-type SGNs and those deficient in Hcn1, Hcn2, or both. We found that HCN1 is the most prominent subunit contributing to Ih in SGNs. Deletion of Hcn1 resulted in reduced conductance (Gh), slower activation kinetics (τfast), and hyperpolarized half-activation (V1/2) potentials. We demonstrate that Ih contributes to SGN function with depolarized resting potentials, depolarized sag and rebound potentials, accelerated rebound spikes after hyperpolarization, and minimized jitter in spike latency for small depolarizing stimuli. Auditory brainstem responses of Hcn1-deficient mice showed longer latencies, suggesting that HCN1-mediated Ih is critical for synchronized spike timing in SGNs. Together, our data indicate that Ih contributes to SGN membrane properties and plays a role in temporal aspects of signal transmission between the cochlea and the brain, which are critical for normal auditory function.
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Affiliation(s)
- Ye-Hyun Kim
- Neuroscience Graduate Program, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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28
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Wang W, Kim HJ, Lee JH, Wong V, Sihn CR, Lv P, Perez Flores MC, Mousavi-Nik A, Doyle KJ, Xu Y, Yamoah EN. Functional significance of K+ channel β-subunit KCNE3 in auditory neurons. J Biol Chem 2014; 289:16802-13. [PMID: 24727472 DOI: 10.1074/jbc.m113.545236] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The KCNE3 β-subunit interacts with and regulates the voltage-dependent gating, kinetics, and pharmacology of a variety of Kv channels in neurons. Because a single neuron may express multiple KCNE3 partners, it is impossible to predict the overall functional relevance of the single transmembrane domain peptide on the pore-forming K(+) channel subunits with which it associates. In the inner ear, the role of KCNE3 is undefined, despite its association with Meniere disease and tinnitus. To gain insights on the functional significance of KCNE3 in auditory neurons, we examined the properties of spiral ganglion neurons (SGNs) in Kcne3 null mutant neurons relative to their age-matched controls. We demonstrate that null deletion of Kcne3 abolishes characteristic wide variations in the resting membrane potentials of SGNs and yields age-dependent alterations in action potential and firing properties of neurons along the contour of the cochlear axis, in comparison with age-matched wild-type neurons. The properties of basal SGNs were markedly altered in Kcne3(-/-) mice compared with the wild-type controls; these include reduced action potential latency, amplitude, and increased firing frequency. Analyses of the underlying conductance demonstrate that null mutation of Kcne3 results in enhanced outward K(+) currents, which is sufficient to explain the ensuing membrane potential changes. Additionally, we have demonstrated that KCNE3 may regulate the activity of Kv4.2 channels in SGNs. Finally, there were developmentally mediated compensatory changes that occurred such that, by 8 weeks after birth, the electrical properties of the null mutant neurons were virtually indistinguishable from the wild-type neurons, suggesting that ion channel remodeling in auditory neurons progresses beyond hearing onset.
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Affiliation(s)
- Wenying Wang
- From the Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang 050017, China, the Department of Anesthesiology and Pain Medicine, Program in Communication and Sensory Sciences, University of California at Davis School of Medicine, Davis, California 95618, and
| | - Hyo Jeong Kim
- the Department of Anesthesiology and Pain Medicine, Program in Communication and Sensory Sciences, University of California at Davis School of Medicine, Davis, California 95618, and
| | - Jeong-Han Lee
- the Department of Anesthesiology and Pain Medicine, Program in Communication and Sensory Sciences, University of California at Davis School of Medicine, Davis, California 95618, and
| | - Victor Wong
- the Department of Anesthesiology and Pain Medicine, Program in Communication and Sensory Sciences, University of California at Davis School of Medicine, Davis, California 95618, and
| | - Choong-Ryoul Sihn
- the Department of Anesthesiology and Pain Medicine, Program in Communication and Sensory Sciences, University of California at Davis School of Medicine, Davis, California 95618, and
| | - Ping Lv
- the Department of Anesthesiology and Pain Medicine, Program in Communication and Sensory Sciences, University of California at Davis School of Medicine, Davis, California 95618, and the Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China
| | - Maria Cristina Perez Flores
- the Department of Anesthesiology and Pain Medicine, Program in Communication and Sensory Sciences, University of California at Davis School of Medicine, Davis, California 95618, and
| | - Atefeh Mousavi-Nik
- the Department of Anesthesiology and Pain Medicine, Program in Communication and Sensory Sciences, University of California at Davis School of Medicine, Davis, California 95618, and
| | - Karen Jo Doyle
- the Department of Anesthesiology and Pain Medicine, Program in Communication and Sensory Sciences, University of California at Davis School of Medicine, Davis, California 95618, and
| | - Yanfang Xu
- From the Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang 050017, China,
| | - Ebenezer N Yamoah
- the Department of Anesthesiology and Pain Medicine, Program in Communication and Sensory Sciences, University of California at Davis School of Medicine, Davis, California 95618, and
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29
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α2δ3 is essential for normal structure and function of auditory nerve synapses and is a novel candidate for auditory processing disorders. J Neurosci 2014; 34:434-45. [PMID: 24403143 DOI: 10.1523/jneurosci.3085-13.2014] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The auxiliary subunit α2δ3 modulates the expression and function of voltage-gated calcium channels. Here we show that α2δ3 mRNA is expressed in spiral ganglion neurons and auditory brainstem nuclei and that the protein is required for normal acoustic responses. Genetic deletion of α2δ3 led to impaired auditory processing, with reduced acoustic startle and distorted auditory brainstem responses. α2δ3(-/-) mice learned to discriminate pure tones, but they failed to discriminate temporally structured amplitude-modulated tones. Light and electron microscopy analyses revealed reduced levels of presynaptic Ca(2+) channels and smaller auditory nerve fiber terminals contacting cochlear nucleus bushy cells. Juxtacellular in vivo recordings of sound-evoked activity in α2δ3(-/-) mice demonstrated impaired transmission at these synapses. Together, our results identify a novel role for the α2δ3 auxiliary subunit in the structure and function of specific synapses in the mammalian auditory pathway and in auditory processing disorders.
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30
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Wang W, Kim HJ, Lv P, Tempel B, Yamoah EN. Association of the Kv1 family of K+ channels and their functional blueprint in the properties of auditory neurons as revealed by genetic and functional analyses. J Neurophysiol 2013; 110:1751-64. [PMID: 23864368 DOI: 10.1152/jn.00290.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Developmental plasticity in spiral ganglion neurons (SGNs) ensues from profound alterations in the functional properties of the developing hair cell (HC). For example, prehearing HCs are spontaneously active. However, at the posthearing stage, HC membrane properties transition to graded receptor potentials. The dendrotoxin (DTX)-sensitive Kv1 channel subunits (Kv1.1, 1.2, and 1.6) shape the firing properties and membrane potential of SGNs, and the expression of the channel undergoes developmental changes. Because of the stochastic nature of Kv subunit heteromultimerization, it has been difficult to determine physiologically relevant subunit-specific interactions and their functions in the underlying mechanisms of Kv1 channel plasticity in SGNs. Using Kcna2 null mutant mice, we demonstrate a surprising paradox in changes in the membrane properties of SGNs. The resting membrane potential of Kcna2(-/-) SGNs was significantly hyperpolarized compared with that of age-matched wild-type (WT) SGNs. Analyses of outward currents in the mutant SGNs suggest an apparent approximately twofold increase in outward K(+) currents. We show that in vivo and in vitro heteromultimerization of Kv1.2 and Kv1.4 α-subunits underlies the striking and unexpected alterations in the properties of SGNs. The results suggest that heteromeric interactions of Kv1.2 and Kv1.4 dominate the defining features of Kv1 channels in SGNs.
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Affiliation(s)
- Wenying Wang
- Program in Communication Science, Center for Neuroscience, University of California, Davis, School of Medicine, Davis, California
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