1
|
Ion channel-related hereditary hearing loss: a narrative review. JOURNAL OF BIO-X RESEARCH 2021. [DOI: 10.1097/jbr.0000000000000108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
|
2
|
Badash I, Quiñones PM, Oghalai KJ, Wang J, Lui CG, Macias-Escriva F, Applegate BE, Oghalai JS. Endolymphatic Hydrops is a Marker of Synaptopathy Following Traumatic Noise Exposure. Front Cell Dev Biol 2021; 9:747870. [PMID: 34805158 PMCID: PMC8602199 DOI: 10.3389/fcell.2021.747870] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 10/20/2021] [Indexed: 12/28/2022] Open
Abstract
After acoustic trauma, there can be loss of synaptic connections between inner hair cells and auditory neurons in the cochlea, which may lead to hearing abnormalities including speech-in-noise difficulties, tinnitus, and hyperacusis. We have previously studied mice with blast-induced cochlear synaptopathy and found that they also developed a build-up of endolymph, termed endolymphatic hydrops. In this study, we used optical coherence tomography to measure endolymph volume in live CBA/CaJ mice exposed to various noise intensities. We quantified the number of synaptic ribbons and postsynaptic densities under the inner hair cells 1 week after noise exposure to determine if they correlated with acute changes in endolymph volume measured in the hours after the noise exposure. After 2 h of noise at an intensity of 95 dB SPL or below, both endolymph volume and synaptic counts remained normal. After exposure to 2 h of 100 dB SPL noise, mice developed endolymphatic hydrops and had reduced synaptic counts in the basal and middle regions of the cochlea. Furthermore, round-window application of hypertonic saline reduced the degree of endolymphatic hydrops that developed after 100 dB SPL noise exposure and partially prevented the reduction in synaptic counts in the cochlear base. Taken together, these results indicate that endolymphatic hydrops correlates with noise-induced cochlear synaptopathy, suggesting that these two pathologic findings have a common mechanistic basis.
Collapse
Affiliation(s)
- Ido Badash
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States
| | - Patricia M Quiñones
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States
| | - Kevin J Oghalai
- Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States
| | - Juemei Wang
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States
| | - Christopher G Lui
- Department of Otolaryngology-Head and Neck Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Frank Macias-Escriva
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States
| | - Brian E Applegate
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States.,Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States
| | - John S Oghalai
- Caruso Department of Otolaryngology-Head and Neck Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States.,Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States
| |
Collapse
|
3
|
Trigila AP, Pisciottano F, Franchini LF. Hearing loss genes reveal patterns of adaptive evolution at the coding and non-coding levels in mammals. BMC Biol 2021; 19:244. [PMID: 34784928 PMCID: PMC8594068 DOI: 10.1186/s12915-021-01170-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 10/21/2021] [Indexed: 11/26/2022] Open
Abstract
Background Mammals possess unique hearing capacities that differ significantly from those of the rest of the amniotes. In order to gain insights into the evolution of the mammalian inner ear, we aim to identify the set of genetic changes and the evolutionary forces that underlie this process. We hypothesize that genes that impair hearing when mutated in humans or in mice (hearing loss (HL) genes) must play important roles in the development and physiology of the inner ear and may have been targets of selective forces across the evolution of mammals. Additionally, we investigated if these HL genes underwent a human-specific evolutionary process that could underlie the evolution of phenotypic traits that characterize human hearing. Results We compiled a dataset of HL genes including non-syndromic deafness genes identified by genetic screenings in humans and mice. We found that many genes including those required for the normal function of the inner ear such as LOXHD1, TMC1, OTOF, CDH23, and PCDH15 show strong signatures of positive selection. We also found numerous noncoding accelerated regions in HL genes, and among them, we identified active transcriptional enhancers through functional enhancer assays in transgenic zebrafish. Conclusions Our results indicate that the key inner ear genes and regulatory regions underwent adaptive evolution in the basal branch of mammals and along the human-specific branch, suggesting that they could have played an important role in the functional remodeling of the cochlea. Altogether, our data suggest that morphological and functional evolution could be attained through molecular changes affecting both coding and noncoding regulatory regions. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01170-6.
Collapse
Affiliation(s)
- Anabella P Trigila
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1428, Buenos Aires, Argentina
| | - Francisco Pisciottano
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1428, Buenos Aires, Argentina.,Current address: Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1428, Buenos Aires, Argentina
| | - Lucía F Franchini
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1428, Buenos Aires, Argentina.
| |
Collapse
|
4
|
Boyd-Gibbins N, Tardieu CH, Blunskyte M, Kirkwood N, Somers J, Albert JT. Turnover and activity-dependent transcriptional control of NompC in the Drosophila ear. iScience 2021; 24:102486. [PMID: 34027326 PMCID: PMC8134069 DOI: 10.1016/j.isci.2021.102486] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 02/17/2021] [Accepted: 04/27/2021] [Indexed: 01/17/2023] Open
Abstract
Across their lives, biological sensors maintain near-constant functional outputs despite countless exogenous and endogenous perturbations. This sensory homeostasis is the product of multiple dynamic equilibria, the breakdown of which contributes to age-related decline. The mechanisms of homeostatic maintenance, however, are still poorly understood. The ears of vertebrates and insects are characterized by exquisite sensitivities but also by marked functional vulnerabilities. Being under the permanent load of thermal and acoustic noise, auditory transducer channels exemplify the homeostatic challenge. We show that (1) NompC-dependent mechanotransducers in the ear of the fruit fly Drosophila melanogaster undergo continual replacement with estimated turnover times of 9.1 hr; (2) a de novo synthesis of NompC can restore transducer function in the adult ears of congenitally hearing-impaired flies; (3) key components of the auditory transduction chain, including NompC, are under activity-dependent transcriptional control, likely forming a transducer-operated mechanosensory gain control system that extends beyond hearing organs. De novo NompC synthesis restores auditory transduction in congenitally deafened flies. Complete turnover of NompC mechanotransducers within less than 24 hr. Activity-dependent transcriptional control of transducers controls auditory function.
Collapse
Affiliation(s)
| | - Camille H Tardieu
- Ear Institute, University College London, 332 Gray's Inn Road, London WC1X 8EE, UK
| | - Modesta Blunskyte
- Ear Institute, University College London, 332 Gray's Inn Road, London WC1X 8EE, UK
| | - Nerissa Kirkwood
- Ear Institute, University College London, 332 Gray's Inn Road, London WC1X 8EE, UK
| | - Jason Somers
- Ear Institute, University College London, 332 Gray's Inn Road, London WC1X 8EE, UK.,The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Joerg T Albert
- Ear Institute, University College London, 332 Gray's Inn Road, London WC1X 8EE, UK.,The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.,Centre for Mathematics and Physics in the Life Sciences and Experimental Biology (CoMPLEX), University College London, Gower Street, London WC1E 6BT, UK.,Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6DE, UK
| |
Collapse
|
5
|
Mechanotransduction channel Piezo is widely expressed in the spider, Cupiennius salei, mechanosensory neurons and central nervous system. Sci Rep 2021; 11:7994. [PMID: 33846502 PMCID: PMC8042031 DOI: 10.1038/s41598-021-87202-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 03/25/2021] [Indexed: 01/01/2023] Open
Abstract
Mechanosensory neurons use mechanotransduction (MET) ion channels to detect mechanical forces and displacements. Proteins that function as MET channels have appeared multiple times during evolution and occur in at least four different families: the DEG/ENaC and TRP channels, as well as the TMC and Piezo proteins. We found twelve putative members of MET channel families in two spider transcriptomes, but detected only one, the Piezo protein, by in situ hybridization in their mechanosensory neurons. In contrast, probes for orthologs of TRP, ENaC or TMC genes that code MET channels in other species did not produce any signals in these cells. An antibody against C. salei Piezo detected the protein in all parts of their mechanosensory cells and in many neurons of the CNS. Unspecific blockers of MET channels, Ruthenium Red and GsMTx4, had no effect on the mechanically activated currents of the mechanosensory VS-3 neurons, but the latter toxin reduced action potential firing when these cells were stimulated electrically. The Piezo protein is expressed throughout the spider nervous system including the mechanosensory neurons. It is possible that it contributes to mechanosensory transduction in spider mechanosensilla, but it must have other functions in peripheral and central neurons.
Collapse
|
6
|
Li S, Yan Z. Mechanotransduction Ion Channels in Hearing and Touch. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1349:371-385. [DOI: 10.1007/978-981-16-4254-8_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
7
|
Zardadi S, Razmara E, Asgaritarghi G, Jafarinia E, Bitarafan F, Rayat S, Almadani N, Morovvati S, Garshasbi M. Novel homozygous variants in the TMC1 and CDH23 genes cause autosomal recessive nonsyndromic hearing loss. Mol Genet Genomic Med 2020; 8:e1550. [PMID: 33205915 PMCID: PMC7767568 DOI: 10.1002/mgg3.1550] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 08/22/2020] [Accepted: 10/29/2020] [Indexed: 12/14/2022] Open
Abstract
Background Hereditary hearing loss (HL) is a heterogeneous and most common sensory neural disorder. At least, 76 genes have been reported in association with autosomal recessive nonsyndromic HL (ARNSHL). Herein, we subjected two patients with bilateral sensorineural HL in two distinct consanguineous Iranian families to figure out the underlying genetic factors. Methods Physical and sensorineural examinations were performed on the patients. Imaging also was applied to unveil any abnormalities in anatomical structures of the middle and inner ear. In order to decipher the possible genetic causes of the verified GJB2‐negative samples, the probands were subjected to whole‐exome sequencing and, subsequently, Sanger sequencing was applied for variant confirmation. Results Clinical examinations showed ARNSHL in the patients. After doing whole exome sequencing, two novel variants were identified that were co‐segregating with HL that were absent in 100 ethnically matched controls. In the first family, a novel homozygous variant, NM_138691.2: c.530T>C; p.(lle177Thr), in TMC1 gene co‐segregated with prelingual ARNSHL. In the second family, NM_022124.6: c.2334G>A; p.(Trp778*) was reported as a nonsense variant causing prelingual ARNSHL. Conclusion These findings can, in turn, endorse how TMC1 and CDH23 screening is critical to detecting HL in Iranian patients. Identifying TMC1 and CDH23 pathogenic variants doubtlessly help in the detailed genotypic characterization of HL.
Collapse
Affiliation(s)
- Safoura Zardadi
- Department of Biology, School of Basic Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Ehsan Razmara
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Golareh Asgaritarghi
- Department of Genetics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | - Ehsan Jafarinia
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Fatemeh Bitarafan
- Department of Cellular and Molecular Biology, North Tehran Branch, Islamic Azad University, Tehran, Iran
| | - Sima Rayat
- Department of Biology, School of Basic Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Navid Almadani
- Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
| | - Saeid Morovvati
- Department of Genetics, Faculty of Advanced Sciences and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Masoud Garshasbi
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| |
Collapse
|
8
|
Jin P, Jan LY, Jan YN. Mechanosensitive Ion Channels: Structural Features Relevant to Mechanotransduction Mechanisms. Annu Rev Neurosci 2020; 43:207-229. [PMID: 32084327 DOI: 10.1146/annurev-neuro-070918-050509] [Citation(s) in RCA: 116] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Activation of mechanosensitive ion channels underlies a variety of fundamental physiological processes that require sensation of mechanical force. Different mechanosensitive channels adapt distinctive structures and mechanotransduction mechanisms to fit their biological roles. How mechanosensitive channels work, especially in animals, has been extensively studied in the past decade. Here we review key findings in the functional and structural characterizations of these channels and highlight the structural features relevant to the mechanotransduction mechanism of each specific channel.
Collapse
Affiliation(s)
- Peng Jin
- Department of Physiology, University of California, San Francisco, California 94158, USA;
| | - Lily Yeh Jan
- Department of Physiology, University of California, San Francisco, California 94158, USA; .,Department of Biochemistry and Biophysics and Howard Hughes Medical Institute, University of California, San Francisco, California 94158, USA
| | - Yuh-Nung Jan
- Department of Physiology, University of California, San Francisco, California 94158, USA; .,Department of Biochemistry and Biophysics and Howard Hughes Medical Institute, University of California, San Francisco, California 94158, USA
| |
Collapse
|
9
|
Jia Y, Zhao Y, Kusakizako T, Wang Y, Pan C, Zhang Y, Nureki O, Hattori M, Yan Z. TMC1 and TMC2 Proteins Are Pore-Forming Subunits of Mechanosensitive Ion Channels. Neuron 2019; 105:310-321.e3. [PMID: 31761710 DOI: 10.1016/j.neuron.2019.10.017] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 09/05/2019] [Accepted: 10/09/2019] [Indexed: 11/28/2022]
Abstract
Transmembrane channel-like (TMC) 1 and 2 are required for the mechanotransduction of mouse inner ear hair cells and localize to the site of mechanotransduction in mouse hair cell stereocilia. However, it remains unclear whether TMC1 and TMC2 are indeed ion channels and whether they can sense mechanical force directly. Here we express TMC1 from the green sea turtle (CmTMC1) and TMC2 from the budgerigar (MuTMC2) in insect cells, purify and reconstitute the proteins, and show that liposome-reconstituted CmTMC1 and MuTMC2 proteins possess ion channel activity. Furthermore, by applying pressure to proteoliposomes, we demonstrate that both CmTMC1 and MuTMC2 proteins can indeed respond to mechanical stimuli. In addition, CmTMC1 mutants corresponding to human hearing loss mutants exhibit reduced or no ion channel activity. Taken together, our results show that the CmTMC1 and MuTMC2 proteins are pore-forming subunits of mechanosensitive ion channels, supporting TMC1 and TMC2 as hair cell transduction channels.
Collapse
Affiliation(s)
- Yanyan Jia
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Department of Neurosurgery at Huashan Hospital, Human Phenome Institute, Ministry of Education Key Laboratory of Contemporary Anthropology, Collaborative Innovation Center of Genetics and Development, Institute of Brain Science, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai 200438, China
| | - Yimeng Zhao
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Multiscale Research Institute for Complex Systems, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Tsukasa Kusakizako
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yao Wang
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Multiscale Research Institute for Complex Systems, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Chengfang Pan
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Department of Neurosurgery at Huashan Hospital, Human Phenome Institute, Ministry of Education Key Laboratory of Contemporary Anthropology, Collaborative Innovation Center of Genetics and Development, Institute of Brain Science, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai 200438, China
| | - Yuwei Zhang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Department of Neurosurgery at Huashan Hospital, Human Phenome Institute, Ministry of Education Key Laboratory of Contemporary Anthropology, Collaborative Innovation Center of Genetics and Development, Institute of Brain Science, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai 200438, China
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
| | - Motoyuki Hattori
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Multiscale Research Institute for Complex Systems, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China.
| | - Zhiqiang Yan
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Department of Neurosurgery at Huashan Hospital, Human Phenome Institute, Ministry of Education Key Laboratory of Contemporary Anthropology, Collaborative Innovation Center of Genetics and Development, Institute of Brain Science, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai 200438, China.
| |
Collapse
|
10
|
Yue X, Sheng Y, Kang L, Xiao R. Distinct functions of TMC channels: a comparative overview. Cell Mol Life Sci 2019; 76:4221-4232. [PMID: 31584127 PMCID: PMC11105308 DOI: 10.1007/s00018-019-03214-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 06/25/2019] [Accepted: 06/28/2019] [Indexed: 12/18/2022]
Abstract
In the past two decades, transmembrane channel-like (TMC) proteins have attracted a significant amount of research interest, because mutations of Tmc1 lead to hereditary deafness. As evolutionarily conserved membrane proteins, TMC proteins are widely involved in diverse sensorimotor functions of many species, such as hearing, chemosensation, egg laying, and food texture detection. Interestingly, recent structural and physiological studies suggest that TMC channels may share a similar membrane topology with the Ca2+-activated Cl- channel TMEM16 and the mechanically activated OSCA1.2/TMEM63 channel. Namely, these channels form dimers and each subunit consists of ten transmembrane segments. Despite this important structural insight, a key question remains: what is the gating mechanism of TMC channels? The major technical hurdle to answer this question is that the reconstitution of TMC proteins as functional ion channels has been challenging in mammalian heterologous systems. Since TMC channels are conserved across taxa, genetic studies of TMC channels in model organisms such as C. elegans, Drosophila, and zebrafish may provide us critical information on the physiological function and regulation of TMCs. Here, we present a comparative overview on the diverse functions of TMC channels in different species.
Collapse
Affiliation(s)
- Xiaomin Yue
- Department of Neurosurgery of the First Affiliated Hospital, Institute of Neuroscience, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Yi Sheng
- Department of Aging and Geriatric Research, Institute on Aging, University of Florida, Gainesville, FL, USA
| | - Lijun Kang
- Department of Neurosurgery of the First Affiliated Hospital, Institute of Neuroscience, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou, China.
| | - Rui Xiao
- Department of Aging and Geriatric Research, Institute on Aging, University of Florida, Gainesville, FL, USA.
- Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, FL, USA.
- Center for Smell and Taste, University of Florida, Gainesville, FL, USA.
| |
Collapse
|
11
|
Soler DC, Manikandan M, Gopal SR, Sloan AE, McCormick TS, Stepanyan R. An uncharacterized region within the N-terminus of mouse TMC1 precludes trafficking to plasma membrane in a heterologous cell line. Sci Rep 2019; 9:15263. [PMID: 31649296 PMCID: PMC6813322 DOI: 10.1038/s41598-019-51336-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 09/24/2019] [Indexed: 12/21/2022] Open
Abstract
Mechanotransduction by hair cell stereocilia lies at the heart of sound detection in vertebrates. Considerable effort has been put forth to identify proteins that comprise the hair cell mechanotransduction apparatus. TMC1, a member of the transmembrane channel-like (TMC) family, was identified as a core protein of the mechanotransduction complex in hair cells. However, the inability of TMC1 to traffic through the endoplasmic reticulum in heterologous cellular systems has hindered efforts to characterize its function and fully identify its role in mechanotransduction. We developed a novel approach that allowed for the detection of uncharacterized protein regions, which preclude trafficking to the plasma membrane (PM) in heterologous cells. Tagging N-terminal fragments of TMC1 with Aquaporin 3 (AQP3) and GFP fusion reporter, which intrinsically label PM in HEK293 cells, indicated that residues at the edges of amino acid sequence 138–168 invoke intracellular localization and/or degradation. This signal is able to preclude surface localization of PM protein AQP3 in HEK293 cells. Substitutions of the residues by alanine or serine corroborated that the information determining the intracellular retention is present within amino acid sequence 138–168 of TMC1 N-terminus. This novel signal may preclude the proper trafficking of TMC1 to the PM in heterologous cells.
Collapse
Affiliation(s)
- D C Soler
- The Department of Neurosurgery, University Hospitals Cleveland Medical Center, Cleveland, OH, USA. .,Brain Tumor and Neuro-Oncology Center, University Hospitals Cleveland Medical Center, Cleveland, OH, USA. .,Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA.
| | - M Manikandan
- Department of Otolaryngology - HNS, Case Western Reserve University, Cleveland, OH, USA
| | - S R Gopal
- Department of Otolaryngology - HNS, Case Western Reserve University, Cleveland, OH, USA
| | - A E Sloan
- The Department of Neurosurgery, University Hospitals Cleveland Medical Center, Cleveland, OH, USA.,Brain Tumor and Neuro-Oncology Center, University Hospitals Cleveland Medical Center, Cleveland, OH, USA.,Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA
| | - T S McCormick
- Department of Dermatology, Case Western Reserve University, Cleveland, OH, USA.,Murdough Family Center for Psoriasis, Case Western Reserve University, Cleveland, OH, USA
| | - R Stepanyan
- Department of Otolaryngology - HNS, Case Western Reserve University, Cleveland, OH, USA. .,Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA.
| |
Collapse
|
12
|
Mammalian Mechanoelectrical Transduction: Structure and Function of Force-Gated Ion Channels. Cell 2019; 179:340-354. [PMID: 31585078 DOI: 10.1016/j.cell.2019.08.049] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 08/08/2019] [Accepted: 08/26/2019] [Indexed: 12/19/2022]
Abstract
The conversion of force into an electrical cellular signal is mediated by the opening of different types of mechanosensitive ion channels (MSCs), including TREK/TRAAK K2P channels, Piezo1/2, TMEM63/OSCA, and TMC1/2. Mechanoelectrical transduction plays a key role in hearing, balance, touch, and proprioception and is also implicated in the autonomic regulation of blood pressure and breathing. Thus, dysfunction of MSCs is associated with a variety of inherited and acquired disease states. Significant progress has recently been made in identifying these channels, solving their structure, and understanding the gating of both hyperpolarizing and depolarizing MSCs. Besides prototypical activation by membrane tension, additional gating mechanisms involving channel curvature and/or tethered elements are at play.
Collapse
|
13
|
Corey DP, Akyuz N, Holt JR. Function and Dysfunction of TMC Channels in Inner Ear Hair Cells. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a033506. [PMID: 30291150 DOI: 10.1101/cshperspect.a033506] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The TMC1 channel was identified as a protein essential for hearing in mouse and human, and recognized as one of a family of eight such proteins in mammals. The TMC family is part of a superfamily of seven branches, which includes the TMEM16s. Vertebrate hair cells express both TMC1 and TMC2. They are located at the tips of stereocilia and are required for hair cell mechanotransduction. TMC1 assembles as a dimer and its similarity to the TMEM16s has enabled a predicted tertiary structure with an ion conduction pore in each subunit of the dimer. Cysteine mutagenesis of the pore supports the role of TMC1 and TMC2 as the core channel proteins of a larger mechanotransduction complex that includes PCDH15 and LHFPL5, and perhaps TMIE, CIB2 and others.
Collapse
Affiliation(s)
- David P Corey
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Nurunisa Akyuz
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Jeffrey R Holt
- Departments of Otolaryngology and Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115
| |
Collapse
|
14
|
Dunbar LA, Patni P, Aguilar C, Mburu P, Corns L, Wells HRR, Delmaghani S, Parker A, Johnson S, Williams D, Esapa CT, Simon MM, Chessum L, Newton S, Dorning J, Jeyarajan P, Morse S, Lelli A, Codner GF, Peineau T, Gopal SR, Alagramam KN, Hertzano R, Dulon D, Wells S, Williams FM, Petit C, Dawson SJ, Brown SDM, Marcotti W, El‐Amraoui A, Bowl MR. Clarin-2 is essential for hearing by maintaining stereocilia integrity and function. EMBO Mol Med 2019; 11:e10288. [PMID: 31448880 PMCID: PMC6728604 DOI: 10.15252/emmm.201910288] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 07/23/2019] [Accepted: 07/26/2019] [Indexed: 11/21/2022] Open
Abstract
Hearing relies on mechanically gated ion channels present in the actin-rich stereocilia bundles at the apical surface of cochlear hair cells. Our knowledge of the mechanisms underlying the formation and maintenance of the sound-receptive structure is limited. Utilizing a large-scale forward genetic screen in mice, genome mapping and gene complementation tests, we identified Clrn2 as a new deafness gene. The Clrn2clarinet/clarinet mice (p.Trp4* mutation) exhibit a progressive, early-onset hearing loss, with no overt retinal deficits. Utilizing data from the UK Biobank study, we could show that CLRN2 is involved in human non-syndromic progressive hearing loss. Our in-depth morphological, molecular and functional investigations establish that while it is not required for initial formation of cochlear sensory hair cell stereocilia bundles, clarin-2 is critical for maintaining normal bundle integrity and functioning. In the differentiating hair bundles, lack of clarin-2 leads to loss of mechano-electrical transduction, followed by selective progressive loss of the transducing stereocilia. Together, our findings demonstrate a key role for clarin-2 in mammalian hearing, providing insights into the interplay between mechano-electrical transduction and stereocilia maintenance.
Collapse
Affiliation(s)
- Lucy A Dunbar
- Mammalian Genetics UnitMRC Harwell InstituteHarwellUK
| | - Pranav Patni
- Déficits Sensoriels ProgressifsInstitut PasteurINSERM UMR‐S 1120Sorbonne UniversitésParisFrance
| | | | | | - Laura Corns
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | - Helena RR Wells
- Department of Twin Research & Genetic EpidemiologyKing's College LondonLondonUK
| | - Sedigheh Delmaghani
- Déficits Sensoriels ProgressifsInstitut PasteurINSERM UMR‐S 1120Sorbonne UniversitésParisFrance
| | - Andrew Parker
- Mammalian Genetics UnitMRC Harwell InstituteHarwellUK
| | - Stuart Johnson
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | | | | | | | | | | | | | | | - Susan Morse
- Mammalian Genetics UnitMRC Harwell InstituteHarwellUK
| | - Andrea Lelli
- Génétique et Physiologie de l'AuditionInstitut PasteurINSERM UMR‐S 1120Collège de FranceSorbonne UniversitésParisFrance
| | | | - Thibault Peineau
- Laboratoire de Neurophysiologie de la Synapse AuditiveUniversité de BordeauxBordeauxFrance
| | - Suhasini R Gopal
- Department of Otolaryngology – Head and Neck SurgeryUniversity Hospitals Cleveland Medical CenterCase Western Reserve UniversityClevelandOHUSA
| | - Kumar N Alagramam
- Department of Otolaryngology – Head and Neck SurgeryUniversity Hospitals Cleveland Medical CenterCase Western Reserve UniversityClevelandOHUSA
| | - Ronna Hertzano
- Department of Otorhinolaryngology Head and Neck Surgery, Anatomy and Neurobiology and Institute for Genome SciencesUniversity of Maryland School of MedicineBaltimoreMDUSA
| | - Didier Dulon
- Laboratoire de Neurophysiologie de la Synapse AuditiveUniversité de BordeauxBordeauxFrance
| | - Sara Wells
- Mary Lyon CentreMRC Harwell InstituteHarwellUK
| | - Frances M Williams
- Department of Twin Research & Genetic EpidemiologyKing's College LondonLondonUK
| | - Christine Petit
- Génétique et Physiologie de l'AuditionInstitut PasteurINSERM UMR‐S 1120Collège de FranceSorbonne UniversitésParisFrance
| | | | | | - Walter Marcotti
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | - Aziz El‐Amraoui
- Déficits Sensoriels ProgressifsInstitut PasteurINSERM UMR‐S 1120Sorbonne UniversitésParisFrance
| | | |
Collapse
|
15
|
Clark S, Elferich J, Gai J, Goehring A, Mitra J, Ha T, Gouaux E. Strategy for Compositional Analysis of the Hair Cell Mechanotransduction Complex Using TIRF Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2019; 25:1266-1267. [PMID: 32025193 PMCID: PMC7001662 DOI: 10.1017/s1431927619007062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Affiliation(s)
- Sarah Clark
- Vollum Institute, Oregon Health & Science University, Portland, United States
| | - Johannes Elferich
- Vollum Institute, Oregon Health & Science University, Portland, United States
| | - Jingpeng Gai
- Vollum Institute, Oregon Health & Science University, Portland, United States
| | - April Goehring
- Vollum Institute, Oregon Health & Science University, Portland, United States
| | - Jaba Mitra
- Department of Biophysics and Biophysical Chemistry, Department of Biophysics, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, United States
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Department of Biophysics, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, United States
- Howard Hughes Medical Institute, Johns Hopkins University, Baltimore, United States
| | - Eric Gouaux
- Vollum Institute, Oregon Health & Science University, Portland, United States
- Howard Hughes Medical Institute, Oregon Health & Science University, Portland, United States
| |
Collapse
|
16
|
Pan B, Akyuz N, Liu XP, Asai Y, Nist-Lund C, Kurima K, Derfler BH, György B, Limapichat W, Walujkar S, Wimalasena LN, Sotomayor M, Corey DP, Holt JR. TMC1 Forms the Pore of Mechanosensory Transduction Channels in Vertebrate Inner Ear Hair Cells. Neuron 2019; 99:736-753.e6. [PMID: 30138589 DOI: 10.1016/j.neuron.2018.07.033] [Citation(s) in RCA: 203] [Impact Index Per Article: 40.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 06/10/2018] [Accepted: 07/19/2018] [Indexed: 11/28/2022]
Abstract
The proteins that form the permeation pathway of mechanosensory transduction channels in inner-ear hair cells have not been definitively identified. Genetic, anatomical, and physiological evidence support a role for transmembrane channel-like protein (TMC) 1 in hair cell sensory transduction, yet the molecular function of TMC proteins remains unclear. Here, we provide biochemical evidence suggesting TMC1 assembles as a dimer, along with structural and sequence analyses suggesting similarity to dimeric TMEM16 channels. To identify the pore region of TMC1, we used cysteine mutagenesis and expressed mutant TMC1 in hair cells of Tmc1/2-null mice. Cysteine-modification reagents rapidly and irreversibly altered permeation properties of mechanosensory transduction. We propose that TMC1 is structurally similar to TMEM16 channels and includes ten transmembrane domains with four domains, S4-S7, that line the channel pore. The data provide compelling evidence that TMC1 is a pore-forming component of sensory transduction channels in auditory and vestibular hair cells.
Collapse
Affiliation(s)
- Bifeng Pan
- Departments of Otolaryngology and Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Nurunisa Akyuz
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Xiao-Ping Liu
- Departments of Otolaryngology and Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Yukako Asai
- Departments of Otolaryngology and Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Carl Nist-Lund
- Departments of Otolaryngology and Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Kiyoto Kurima
- Molecular Biology and Genetics Section, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, USA
| | - Bruce H Derfler
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Bence György
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Walrati Limapichat
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Sanket Walujkar
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Lahiru N Wimalasena
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - David P Corey
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA.
| | - Jeffrey R Holt
- Departments of Otolaryngology and Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.
| |
Collapse
|
17
|
Zhang W, Wang S, Zhang X, Liu K, Song J, Leng X, Luo R, Ran L. Transmembrane Channel-Like 5 (TMC5) promotes prostate cancer cell proliferation through cell cycle regulation. Biochimie 2019; 165:115-122. [PMID: 31356847 DOI: 10.1016/j.biochi.2019.07.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 07/22/2019] [Indexed: 12/24/2022]
Abstract
BACKGROUND In this study, we aimed to investigate the biological functions of Transmembrane Channel-Like 5 (TMC5) by bioinformatics and molecular biology methods in prostate cancer (PCa). METHODS We assessed the mRNA expression level of TMC5 in PCa with public database the Cancer Genome Atlas (TCGA) and Oncomine. The biological functions were demonstrated by bioinformatics methods and siRNA mediated knockdown experiments. Reverse transcription polymerase chain reaction (RT-PCR), immunohistochemical (IHC) experiments and microarray analysis were performed to confirm the results. RESULTS TMC5 expression level was significantly up-regulated in 4 independent PCa cohorts compared to normal group. Moreover, TMC5 has higher diagnostic efficiency than PSA-KLK3 (AUC (Area Under Curve) = 0.772, P < 0.001). The high expression of TMC5 was associated with clinical Gleason score, prostate-specific antigen (PSA) level, androgen receptor (AR) activity score and the genes which were known frequently mutated in PCa progression (P < 0.05). Functionally, Gene Otology (GO) analysis suggested that TMC5 was related to cell development; TMC5 knockdown significantly inhibited PCa cells proliferation by arresting cell cycle at G1 phase. Drug sensitivity experiments showed TMC5 knockdown significantly enhanced cells sensitivity to 5-Fluorouracil. Microarray analysis showed TMC5 knockdown significantly inhibited cell cycle and tumor progression. CONCLUSION Our findings revealed that TMC5 promoted PCa cell proliferation through cell cycle regulation and could be a powerful and hopeful target for PCa treatment.
Collapse
Affiliation(s)
- Wanfeng Zhang
- Department of Bioinformatics, Chongqing Medical University, Chongqing, 400016, China.
| | - Sen Wang
- Department of Biochemistry and Molecular Biology, Chongqing Medical University, Chongqing, 400016, China.
| | - Xianqin Zhang
- Department of Biochemistry and Molecular Biology, Chongqing Medical University, Chongqing, 400016, China.
| | - Kun Liu
- Department of Biochemistry and Molecular Biology, Chongqing Medical University, Chongqing, 400016, China.
| | - Jing Song
- Department of Bioinformatics, Chongqing Medical University, Chongqing, 400016, China.
| | - Xue Leng
- Department of Biochemistry and Molecular Biology, Chongqing Medical University, Chongqing, 400016, China.
| | - Ruihan Luo
- Department of Bioinformatics, Chongqing Medical University, Chongqing, 400016, China.
| | - Longke Ran
- Department of Bioinformatics, Chongqing Medical University, Chongqing, 400016, China.
| |
Collapse
|
18
|
Cunningham CL, Müller U. Molecular Structure of the Hair Cell Mechanoelectrical Transduction Complex. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a033167. [PMID: 30082452 DOI: 10.1101/cshperspect.a033167] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cochlear hair cells employ mechanically gated ion channels located in stereocilia that open in response to sound wave-induced motion of the basilar membrane, converting mechanical stimulation to graded changes in hair cell membrane potential. Membrane potential changes in hair cells cause neurotransmitter release from hair cells that initiate electrical signals in the nerve terminals of afferent fibers from spiral ganglion neurons. These signals are then propagated within the central nervous system (CNS) to mediate the sensation of hearing. Recent studies show that the mechanoelectrical transduction (MET) machinery of hair cells is formed by an ensemble of proteins. Candidate components forming the MET channel have been identified, but none alone fulfills all criteria necessary to define them as pore-forming subunits of the MET channel. We will review here recent findings on the identification and function of proteins that are components of the MET machinery in hair cells and consider remaining open questions.
Collapse
Affiliation(s)
- Christopher L Cunningham
- The Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, Maryland 21205
| | - Ulrich Müller
- The Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, Maryland 21205
| |
Collapse
|
19
|
Baker CVH, Modrell MS. Insights into Electroreceptor Development and Evolution from Molecular Comparisons with Hair Cells. Integr Comp Biol 2019; 58:329-340. [PMID: 29846597 DOI: 10.1093/icb/icy037] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The vertebrate lateral line system comprises a mechanosensory division, with neuromasts containing hair cells that detect local water movement ("distant touch"); and an electrosensory division, with electrosensory organs that detect the weak, low-frequency electric fields surrounding other animals in water (primarily used for hunting). The entire lateral line system was lost in the amniote lineage with the transition to fully terrestrial life; the electrosensory division was lost independently in several lineages, including the ancestors of frogs and of teleost fishes. (Electroreception with different characteristics subsequently evolved independently within two teleost lineages.) Recent gene expression studies in a non-teleost actinopterygian fish suggest that electroreceptor ribbon synapses employ the same transmission mechanisms as hair cell ribbon synapses, and show that developing electrosensory organs express transcription factors essential for hair cell development, including Atoh1 and Pou4f3. Previous hypotheses for electroreceptor evolution suggest either that electroreceptors and hair cells evolved independently in the vertebrate ancestor from a common ciliated secondary cell, or that electroreceptors evolved from hair cells. The close developmental and putative physiological similarities implied by the gene expression data support the latter hypothesis, i.e., that electroreceptors evolved in the vertebrate ancestor as a "sister cell-type" to lateral line hair cells.
Collapse
Affiliation(s)
- Clare V H Baker
- Department of Physiology, Development and Neuroscience, University of Cambridge, Anatomy Building, Downing Street, Cambridge CB2 3DY, UK
| | - Melinda S Modrell
- Department of Physiology, Development and Neuroscience, University of Cambridge, Anatomy Building, Downing Street, Cambridge CB2 3DY, UK
| |
Collapse
|
20
|
Harkcom WT, Papanikolaou M, Kanda V, Crump SM, Abbott GW. KCNQ1 rescues TMC1 plasma membrane expression but not mechanosensitive channel activity. J Cell Physiol 2019; 234:13361-13369. [PMID: 30613966 DOI: 10.1002/jcp.28013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 11/28/2018] [Indexed: 01/21/2023]
Abstract
Transmembrane channel-like protein isoform 1 (TMC1) is essential for the generation of mechano-electrical transducer currents in hair cells of the inner ear. TMC1 disruption causes hair cell degeneration and deafness in mice and humans. Although thought to be expressed at the cell surface in vivo, TMC1 remains in the endoplasmic reticulum when heterologously expressed in standard cell lines, precluding determination of its roles in mechanosensing and pore formation. Here, we report that the KCNQ1 Kv channel forms complexes with TMC1 and rescues its surface expression when coexpressed in Chinese Hamster Ovary cells. TMC1 rescue is specific for KCNQ1 within the KCNQ family, is prevented by a KCNQ1 trafficking-deficient mutation, and is influenced by KCNE β subunits and inhibition of KCNQ1 endocytosis. TMC1 lowers KCNQ1 and KCNQ1-KCNE1 K+ currents, and despite the surface expression, it does not detectably respond to mechanical stimulation or high salt. We conclude that TMC1 is not intrinsically mechano- or osmosensitive but has the capacity for cell surface expression, and requires partner protein(s) for surface expression and mechanosensitivity. We suggest that KCNQ1, expression of which is not thought to overlap with TMC1 in hair cells, is a proxy partner bearing structural elements or a sequence motif reminiscent of a true in vivo TMC1 hair cell partner. Discovery of the first reported strategy to rescue TMC1 surface expression should aid future studies of the TMC1 function and native partners.
Collapse
Affiliation(s)
- William T Harkcom
- Pharmacology Department, Weill Medical College of Cornell University, New York, New York
| | - Maria Papanikolaou
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
| | - Vikram Kanda
- Pharmacology Department, Weill Medical College of Cornell University, New York, New York
| | - Shawn M Crump
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
| |
Collapse
|
21
|
Fettiplace R, Nam JH. Tonotopy in calcium homeostasis and vulnerability of cochlear hair cells. Hear Res 2018; 376:11-21. [PMID: 30473131 DOI: 10.1016/j.heares.2018.11.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 11/05/2018] [Accepted: 11/08/2018] [Indexed: 12/18/2022]
Abstract
Ototoxicity, noise overstimulation, or aging, can all produce hearing loss with similar properties, in which outer hair cells (OHCs), principally those at the high-frequency base of the cochlea, are preferentially affected. We suggest that the differential vulnerability may partly arise from differences in Ca2+ balance among cochlear locations. Homeostasis is determined by three factors: Ca2+ influx mainly via mechanotransducer (MET) channels; buffering by calcium-binding proteins and organelles like mitochondria; and extrusion by the plasma membrane CaATPase pump. We review quantification of these parameters and use our experimentally-determined values to model changes in cytoplasmic and mitochondrial Ca2+ during Ca2+ influx through the MET channels. We suggest that, in OHCs, there are two distinct micro-compartments for Ca2+ handling, one in the hair bundle and the other in the cell soma. One conclusion of the modeling is that there is a tonotopic gradient in the ability of OHCs to handle the Ca2+ load, which correlates with their vulnerability to environmental challenges. High-frequency basal OHCs are the most susceptible because they have much larger MET currents and have smaller dimensions than low-frequency apical OHCs.
Collapse
Affiliation(s)
- Robert Fettiplace
- Department of Neuroscience, University of Wisconsin, Madison, WI, 53706, USA.
| | - Jong-Hoon Nam
- Departments of Mechanical Engineering and Biomedical Engineering, University of Rochester, Rochester, NY, 14627, USA
| |
Collapse
|
22
|
Jojoa-Cruz S, Saotome K, Murthy SE, Tsui CCA, Sansom MS, Patapoutian A, Ward AB. Cryo-EM structure of the mechanically activated ion channel OSCA1.2. eLife 2018; 7:41845. [PMID: 30382939 PMCID: PMC6235563 DOI: 10.7554/elife.41845] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Accepted: 10/11/2018] [Indexed: 12/15/2022] Open
Abstract
Mechanically activated ion channels underlie touch, hearing, shear-stress sensing, and response to turgor pressure. OSCA/TMEM63s are a newly-identified family of eukaryotic mechanically activated ion channels opened by membrane tension. The structural underpinnings of OSCA/TMEM63 function are not explored. Here, we elucidate high resolution cryo-electron microscopy structures of OSCA1.2, revealing a dimeric architecture containing eleven transmembrane helices per subunit and surprising topological similarities to TMEM16 proteins. We locate the ion permeation pathway within each subunit by demonstrating that a conserved acidic residue is a determinant of channel conductance. Molecular dynamics simulations reveal membrane interactions, suggesting the role of lipids in OSCA1.2 gating. These results lay a foundation to decipher how the structural organization of OSCA/TMEM63 is suited for their roles as MA ion channels.
Collapse
Affiliation(s)
- Sebastian Jojoa-Cruz
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, California, United States
| | - Kei Saotome
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, California, United States.,Department of Neuroscience, Dorris Neuroscience Center, Howard Hughes Medical Institute, The Scripps Research Institute, California, United States
| | - Swetha E Murthy
- Department of Neuroscience, Dorris Neuroscience Center, Howard Hughes Medical Institute, The Scripps Research Institute, California, United States
| | - Che Chun Alex Tsui
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, California, United States.,Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Mark Sp Sansom
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Ardem Patapoutian
- Department of Neuroscience, Dorris Neuroscience Center, Howard Hughes Medical Institute, The Scripps Research Institute, California, United States
| | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, California, United States
| |
Collapse
|
23
|
Jaiganesh A, Narui Y, Araya-Secchi R, Sotomayor M. Beyond Cell-Cell Adhesion: Sensational Cadherins for Hearing and Balance. Cold Spring Harb Perspect Biol 2018; 10:a029280. [PMID: 28847902 PMCID: PMC6008173 DOI: 10.1101/cshperspect.a029280] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cadherins form a large family of proteins often involved in calcium-dependent cellular adhesion. Although classical members of the family can provide a physical bond between cells, a subset of special cadherins use their extracellular domains to interlink apical specializations of single epithelial sensory cells. Two of these cadherins, cadherin-23 (CDH23) and protocadherin-15 (PCDH15), form extracellular "tip link" filaments that connect apical bundles of stereocilia on hair cells essential for inner-ear mechanotransduction. As these bundles deflect in response to mechanical stimuli from sound or head movements, tip links gate hair-cell mechanosensitive channels to initiate sensory perception. Here, we review the unusual and diverse structural properties of these tip-link cadherins and the functional significance of their deafness-related missense mutations. Based on the structural features of CDH23 and PCDH15, we discuss the elasticity of tip links and models that bridge the gap between the nanomechanics of cadherins and the micromechanics of hair-cell bundles during inner-ear mechanotransduction.
Collapse
Affiliation(s)
- Avinash Jaiganesh
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Yoshie Narui
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Raul Araya-Secchi
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| |
Collapse
|
24
|
Abstract
Sensory hair cells are specialized secondary sensory cells that mediate our senses of hearing, balance, linear acceleration, and angular acceleration (head rotation). In addition, hair cells in fish and amphibians mediate sensitivity to water movement through the lateral line system, and closely related electroreceptive cells mediate sensitivity to low-voltage electric fields in the aquatic environment of many fish species and several species of amphibian. Sensory hair cells share many structural and functional features across all vertebrate groups, while at the same time they are specialized for employment in a wide variety of sensory tasks. The complexity of hair cell structure is large, and the diversity of hair cell applications in sensory systems exceeds that seen for most, if not all, sensory cell types. The intent of this review is to summarize the more significant structural features and some of the more interesting and important physiological mechanisms that have been elucidated thus far. Outside vertebrates, hair cells are only known to exist in the coronal organ of tunicates. Electrical resonance, electromotility, and their exquisite mechanical sensitivity all contribute to the attractiveness of hair cells as a research subject.
Collapse
|
25
|
Ballesteros A, Fenollar-Ferrer C, Swartz KJ. Structural relationship between the putative hair cell mechanotransduction channel TMC1 and TMEM16 proteins. eLife 2018; 7:38433. [PMID: 30063209 PMCID: PMC6067890 DOI: 10.7554/elife.38433] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 07/09/2018] [Indexed: 02/03/2023] Open
Abstract
The hair cell mechanotransduction (MET) channel complex is essential for hearing, yet it's molecular identity and structure remain elusive. The transmembrane channel-like 1 (TMC1) protein localizes to the site of the MET channel, interacts with the tip-link responsible for mechanical gating, and genetic alterations in TMC1 alter MET channel properties and cause deafness, supporting the hypothesis that TMC1 forms the MET channel. We generated a model of TMC1 based on X-ray and cryo-EM structures of TMEM16 proteins, revealing the presence of a large cavity near the protein-lipid interface that also harbors the Beethoven mutation, suggesting that it could function as a permeation pathway. We also find that hair cells are permeable to 3 kDa dextrans, and that dextran permeation requires TMC1/2 proteins and functional MET channels, supporting the presence of a large permeation pathway and the hypothesis that TMC1 is a pore forming subunit of the MET channel complex.
Collapse
Affiliation(s)
- Angela Ballesteros
- Molecular Physiology and Biophysics Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Cristina Fenollar-Ferrer
- Laboratory of Molecular & Cellular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, United States.,Laboratory of Molecular Genetics, National Institute of Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States.,Molecular Biology and Genetics Section, National Institute of Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Kenton Jon Swartz
- Molecular Physiology and Biophysics Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| |
Collapse
|
26
|
Resistance to neomycin ototoxicity in the extreme basal (hook) region of the mouse cochlea. Histochem Cell Biol 2018; 150:281-289. [PMID: 29862415 DOI: 10.1007/s00418-018-1683-8] [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] [Accepted: 05/26/2018] [Indexed: 10/14/2022]
Abstract
Aminoglycoside ototoxicity results in permanent loss of the sensory hair cells in the mammalian cochlea. It usually begins at the basal turn causing high-frequency hearing loss. Here we describe previously unreported resistance of hair cells to neomycin ototoxicity in the extreme basal (hook) region of the developing cochlea of the C57BL/6 mouse. Organ of Corti explants from mice at postnatal day 3 were incubated (37 °C, 5% CO2) in normal culture medium for 19.5 h prior to and after exposure to neomycin (1 mM, 3 h). To study neomycin uptake in the hair cells, cochlear explants were incubated with Neomycin Texas-red (NTR) conjugate. As expected, exposure to neomycin significantly reduced the survival of inner (IHC) and outer hair cells (OHC). IHC survival rate was high in the apical segment and low in the basal segment. OHC were well preserved in the apical and hook regions, with substantial OHC loss in the basal segment. The NTR uptake study demonstrated that the high survival rate in the extreme basal turn OHC was associated with low NTR uptake. Treatment with a calcium chelator (BAPTA), which disrupts the opening of mechanoelectrical (MET) transduction channels, abolished or reduced NTR uptake in the hair cells throughout the cochlea. This confirmed the essential role of MET channels in neomycin uptake and implied that the transduction channels could be impaired in the hook region of the developing mouse cochlea, possibly as a result of the cadherin 23 mutation responsible for the progressive deafness in C57BL/6 mice.
Collapse
|
27
|
Li T, Bellen HJ, Groves AK. Using Drosophila to study mechanisms of hereditary hearing loss. Dis Model Mech 2018; 11:11/6/dmm031492. [PMID: 29853544 PMCID: PMC6031363 DOI: 10.1242/dmm.031492] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Johnston's organ - the hearing organ of Drosophila - has a very different structure and morphology to that of the hearing organs of vertebrates. Nevertheless, it is becoming clear that vertebrate and invertebrate auditory organs share many physiological, molecular and genetic similarities. Here, we compare the molecular and cellular features of hearing organs in Drosophila with those of vertebrates, and discuss recent evidence concerning the functional conservation of Usher proteins between flies and mammals. Mutations in Usher genes cause Usher syndrome, the leading cause of human deafness and blindness. In Drosophila, some Usher syndrome proteins appear to physically interact in protein complexes that are similar to those described in mammals. This functional conservation highlights a rational role for Drosophila as a model for studying hearing, and for investigating the evolution of auditory organs, with the aim of advancing our understanding of the genes that regulate human hearing and the pathogenic mechanisms that lead to deafness.
Collapse
Affiliation(s)
- Tongchao Li
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Hugo J Bellen
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA.,Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Andrew K Groves
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA .,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.,Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| |
Collapse
|
28
|
Lin LY, Yeh YH, Hung GY, Lin CH, Hwang PP, Horng JL. Role of Calcium-Sensing Receptor in Mechanotransducer-Channel-Mediated Ca 2+ Influx in Hair Cells of Zebrafish Larvae. Front Physiol 2018; 9:649. [PMID: 29899708 PMCID: PMC5988855 DOI: 10.3389/fphys.2018.00649] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 05/14/2018] [Indexed: 01/16/2023] Open
Abstract
The calcium-sensing receptor (CaSR) is an extracellular Ca2+ sensor that plays a critical role in maintaining Ca2+ homeostasis in several organs, including the parathyroid gland and kidneys. In this study, through in situ hybridization, the expression of CaSR mRNA was found in the neuromasts of zebrafish larvae. Immunohistochemistry further demonstrated that the CaSR protein was present in neuromast hair cell stereocilia and basolateral membranes. Based on the expression and subcellular localization of the CaSR in hair cells, we hypothesized that the CaSR is expressed in zebrafish lateral-line hair cells to regulate mechanotransducer (MET)-channel-mediated Ca2+ entry. Using the scanning ion-selective electrode technique, MET-channel-mediated Ca2+ influx at the stereocilia of hair cells was measured in intact larvae. Ca2+ influx was suppressed after larvae were pretreated with a CaSR activator (R-568) or high-Ca2+ (HCa) medium. Gene knockdown by using morpholino oligonucleotides decreased CaSR expression in hair cells and eliminated the effects of R-568 and HCa on Ca2+ influx. In addition, we found that treatment with R-568 attenuated neomycin-induced hair cell death. This study is the first to demonstrate that the CaSR is involved in mechanotransduction in zebrafish hair cells.
Collapse
Affiliation(s)
- Li-Yih Lin
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Ya-Hsin Yeh
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Giun-Yi Hung
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan.,Department of Pediatrics, Taipei Veterans General Hospital, Taipei, Taiwan.,Department of Pediatrics, Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Chia-Hao Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan.,Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Jiun-Lin Horng
- Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| |
Collapse
|
29
|
Electrophysiological experiments in microgravity: lessons learned and future challenges. NPJ Microgravity 2018; 4:7. [PMID: 29619409 PMCID: PMC5876337 DOI: 10.1038/s41526-018-0042-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 03/07/2018] [Accepted: 03/07/2018] [Indexed: 02/08/2023] Open
Abstract
Advances in electrophysiological experiments have led to the discovery of mechanosensitive ion channels (MSCs) and the identification of the physiological function of specific MSCs. They are believed to play important roles in mechanosensitive pathways by allowing for cells to sense their mechanical environment. However, the physiological function of many MSCs has not been conclusively identified. Therefore, experiments have been developed that expose cells to various mechanical loads, such as shear flow, membrane indentation, osmotic challenges and hydrostatic pressure. In line with these experiments, mechanical unloading, as experienced in microgravity, represents an interesting alternative condition, since exposure to microgravity leads to a series of physiological adaption processes. As outlined in this review, electrophysiological experiments performed in microgravity have shown an influence of gravity on biological functions depending on ion channels at all hierarchical levels, from the cellular level to organs. In this context, calcium signaling represents an interesting cellular pathway, as it involves the direct action of calcium-permeable ion channels, and specific gravitatic cells have linked graviperception to this pathway. Multiple key proteins in the graviperception pathways have been identified. However, measurements on vertebrae cells have revealed controversial results. In conclusion, electrophysiological experiments in microgravity have shown that ion-channel-dependent physiological processes are altered in mechanically unloaded conditions. Future experiments may provide a better understanding of the underlying mechanisms.
Collapse
|
30
|
Yue X, Zhao J, Li X, Fan Y, Duan D, Zhang X, Zou W, Sheng Y, Zhang T, Yang Q, Luo J, Duan S, Xiao R, Kang L. TMC Proteins Modulate Egg Laying and Membrane Excitability through a Background Leak Conductance in C. elegans. Neuron 2018; 97:571-585.e5. [PMID: 29395910 DOI: 10.1016/j.neuron.2017.12.041] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 10/24/2017] [Accepted: 12/26/2017] [Indexed: 12/13/2022]
Abstract
Membrane excitability is a fundamentally important feature for all excitable cells including both neurons and muscle cells. However, the background depolarizing conductances in excitable cells, especially in muscle cells, are not well characterized. Although mutations in transmembrane channel-like (TMC) proteins TMC1 and TMC2 cause deafness and vestibular defects in mammals, their precise action modes are elusive. Here, we discover that both TMC-1 and TMC-2 are required for normal egg laying in C. elegans. Mutations in these TMC proteins cause membrane hyperpolarization and disrupt the rhythmic calcium activities in both neurons and muscles involved in egg laying. Mechanistically, TMC proteins enhance membrane depolarization through background leak currents and ectopic expression of both C. elegans and mammalian TMC proteins results in membrane depolarization. Therefore, we have identified an unexpected role of TMC proteins in modulating membrane excitability. Our results may provide mechanistic insights into the functions of TMC proteins in hearing loss and other diseases.
Collapse
Affiliation(s)
- Xiaomin Yue
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Jian Zhao
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiao Li
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Yuedan Fan
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Duo Duan
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiaoyan Zhang
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Wenjuan Zou
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Yi Sheng
- Department of Aging and Geriatric Research, Institute on Aging, University of Florida, Gainesville, FL, USA
| | - Ting Zhang
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Qian Yang
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Jianhong Luo
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Shumin Duan
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Rui Xiao
- Department of Aging and Geriatric Research, Institute on Aging, University of Florida, Gainesville, FL, USA; Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, FL, USA; Center for Smell and Taste, University of Florida, Gainesville, FL, USA.
| | - Lijun Kang
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China.
| |
Collapse
|
31
|
Albert JT, Kozlov AS. Comparative Aspects of Hearing in Vertebrates and Insects with Antennal Ears. Curr Biol 2017; 26:R1050-R1061. [PMID: 27780047 DOI: 10.1016/j.cub.2016.09.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The evolution of hearing in terrestrial animals has resulted in remarkable adaptations enabling exquisitely sensitive sound detection by the ear and sophisticated sound analysis by the brain. In this review, we examine several such characteristics, using examples from insects and vertebrates. We focus on two strong and interdependent forces that have been shaping the auditory systems across taxa: the physical environment of auditory transducers on the small, subcellular scale, and the sensory-ecological environment within which hearing happens, on a larger, evolutionary scale. We briefly discuss acoustical feature selectivity and invariance in the central auditory system, highlighting a major difference between insects and vertebrates as well as a major similarity. Through such comparisons within a sensory ecological framework, we aim to emphasize general principles underlying acute sensitivity to airborne sounds.
Collapse
Affiliation(s)
- Joerg T Albert
- UCL Ear Institute, 332 Gray's Inn Road, London WC1X 8EE, UK.
| | - Andrei S Kozlov
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK.
| |
Collapse
|
32
|
Fettiplace R. Hair Cell Transduction, Tuning, and Synaptic Transmission in the Mammalian Cochlea. Compr Physiol 2017; 7:1197-1227. [PMID: 28915323 DOI: 10.1002/cphy.c160049] [Citation(s) in RCA: 188] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Sound pressure fluctuations striking the ear are conveyed to the cochlea, where they vibrate the basilar membrane on which sit hair cells, the mechanoreceptors of the inner ear. Recordings of hair cell electrical responses have shown that they transduce sound via submicrometer deflections of their hair bundles, which are arrays of interconnected stereocilia containing the mechanoelectrical transducer (MET) channels. MET channels are activated by tension in extracellular tip links bridging adjacent stereocilia, and they can respond within microseconds to nanometer displacements of the bundle, facilitated by multiple processes of Ca2+-dependent adaptation. Studies of mouse mutants have produced much detail about the molecular organization of the stereocilia, the tip links and their attachment sites, and the MET channels localized to the lower end of each tip link. The mammalian cochlea contains two categories of hair cells. Inner hair cells relay acoustic information via multiple ribbon synapses that transmit rapidly without rundown. Outer hair cells are important for amplifying sound-evoked vibrations. The amplification mechanism primarily involves contractions of the outer hair cells, which are driven by changes in membrane potential and mediated by prestin, a motor protein in the outer hair cell lateral membrane. Different sound frequencies are separated along the cochlea, with each hair cell being tuned to a narrow frequency range; amplification sharpens the frequency resolution and augments sensitivity 100-fold around the cell's characteristic frequency. Genetic mutations and environmental factors such as acoustic overstimulation cause hearing loss through irreversible damage to the hair cells or degeneration of inner hair cell synapses. © 2017 American Physiological Society. Compr Physiol 7:1197-1227, 2017.
Collapse
Affiliation(s)
- Robert Fettiplace
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| |
Collapse
|
33
|
Kirkwood NK, O'Reilly M, Derudas M, Kenyon EJ, Huckvale R, van Netten SM, Ward SE, Richardson GP, Kros CJ. d-Tubocurarine and Berbamine: Alkaloids That Are Permeant Blockers of the Hair Cell's Mechano-Electrical Transducer Channel and Protect from Aminoglycoside Toxicity. Front Cell Neurosci 2017; 11:262. [PMID: 28928635 PMCID: PMC5591855 DOI: 10.3389/fncel.2017.00262] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 08/14/2017] [Indexed: 12/03/2022] Open
Abstract
Aminoglycoside antibiotics are widely used for the treatment of life-threatening bacterial infections, but cause permanent hearing loss in a substantial proportion of treated patients. The sensory hair cells of the inner ear are damaged following entry of these antibiotics via the mechano-electrical transducer (MET) channels located at the tips of the hair cell's stereocilia. d-Tubocurarine (dTC) is a MET channel blocker that reduces the loading of gentamicin-Texas Red (GTTR) into rat cochlear hair cells and protects them from gentamicin treatment. Berbamine is a structurally related alkaloid that reduces GTTR labeling of zebrafish lateral-line hair cells and protects them from aminoglycoside-induced cell death. Both compounds are thought to reduce aminoglycoside entry into hair cells through the MET channels. Here we show that dTC (≥6.25 μM) or berbamine (≥1.55 μM) protect zebrafish hair cells in vivo from neomycin (6.25 μM, 1 h). Protection of zebrafish hair cells against gentamicin (10 μM, 6 h) was provided by ≥25 μM dTC or ≥12.5 μM berbamine. Hair cells in mouse cochlear cultures are protected from longer-term exposure to gentamicin (5 μM, 48 h) by 20 μM berbamine or 25 μM dTC. Berbamine is, however, highly toxic to mouse cochlear hair cells at higher concentrations (≥30 μM) whilst dTC is not. The absence of toxicity in the zebrafish assays prompts caution in extrapolating results from zebrafish neuromasts to mammalian cochlear hair cells. MET current recordings from mouse outer hair cells (OHCs) show that both compounds are permeant open-channel blockers, rapidly and reversibly blocking the MET channel with half-blocking concentrations of 2.2 μM (dTC) and 2.8 μM (berbamine) in the presence of 1.3 mM Ca2+ at −104 mV. Berbamine, but not dTC, also blocks the hair cell's basolateral K+ current, IK,neo, and modeling studies indicate that berbamine permeates the MET channel more readily than dTC. These studies reveal key properties of MET-channel blockers required for the future design of successful otoprotectants.
Collapse
Affiliation(s)
- Nerissa K Kirkwood
- Sussex Neuroscience, School of Life Sciences, University of SussexBrighton, United Kingdom
| | - Molly O'Reilly
- Sussex Neuroscience, School of Life Sciences, University of SussexBrighton, United Kingdom
| | - Marco Derudas
- Sussex Drug Discovery Centre, School of Life Sciences, University of SussexBrighton, United Kingdom
| | - Emma J Kenyon
- Sussex Neuroscience, School of Life Sciences, University of SussexBrighton, United Kingdom
| | - Rosemary Huckvale
- Sussex Drug Discovery Centre, School of Life Sciences, University of SussexBrighton, United Kingdom
| | - Sietse M van Netten
- Institute of Artificial Intelligence and Cognitive Engineering, University of GroningenGroningen, Netherlands
| | - Simon E Ward
- Sussex Drug Discovery Centre, School of Life Sciences, University of SussexBrighton, United Kingdom
| | - Guy P Richardson
- Sussex Neuroscience, School of Life Sciences, University of SussexBrighton, United Kingdom
| | - Corné J Kros
- Sussex Neuroscience, School of Life Sciences, University of SussexBrighton, United Kingdom
| |
Collapse
|
34
|
CIB2 interacts with TMC1 and TMC2 and is essential for mechanotransduction in auditory hair cells. Nat Commun 2017; 8:43. [PMID: 28663585 PMCID: PMC5491523 DOI: 10.1038/s41467-017-00061-1] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 05/02/2017] [Indexed: 11/24/2022] Open
Abstract
Inner ear hair cells detect sound through deflection of stereocilia, the microvilli-like projections that are arranged in rows of graded heights. Calcium and integrin-binding protein 2 is essential for hearing and localizes to stereocilia, but its exact function is unknown. Here, we have characterized two mutant mouse lines, one lacking calcium and integrin-binding protein 2 and one carrying a human deafness-related Cib2 mutation, and show that both are deaf and exhibit no mechanotransduction in auditory hair cells, despite the presence of tip links that gate the mechanotransducer channels. In addition, mechanotransducing shorter row stereocilia overgrow in hair cell bundles of both Cib2 mutants. Furthermore, we report that calcium and integrin-binding protein 2 binds to the components of the hair cell mechanotransduction complex, TMC1 and TMC2, and these interactions are disrupted by deafness-causing Cib2 mutations. We conclude that calcium and integrin-binding protein 2 is required for normal operation of the mechanotransducer channels and is involved in limiting the growth of transducing stereocilia. Inner ear hair cells detect sound through deflection of stereocilia that harbor mechanically-gated channels. Here the authors show that protein responsible for Usher syndrome, CIB2, interacts with these channels and is essential for their function and hearing in mice.
Collapse
|
35
|
Over-expression of myosin7A in cochlear hair cells of circling mice. Lab Anim Res 2017; 33:1-7. [PMID: 28400833 PMCID: PMC5385277 DOI: 10.5625/lar.2017.33.1.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/03/2017] [Accepted: 03/16/2017] [Indexed: 01/15/2023] Open
Abstract
Circling mouse (C57BL/6J-cir/cir) deleted the transmembrane inner ear (Tmie) gene is an animal model for human non-syndromic recessive deafness, DFNB6. In circling mouse, hair cells in the cochlea have degenerated and hair bundles have become irregularity as time goes on. Tmie protein carries out a function of the mechanoelectrical transduction channel in cochlear hair cells. Myosin7a (MYO7A) protein has key roles in development of the cochlear hair bundles as well as in the function of cochlear hair cells. To find whether Tmie protein interacts with MYO7A proteins in the cochlea postnatal developmental stage, we investigated expression of the MYO7A proteins in the cochlear hair cells of circling mice by western blot analysis and whole mount immunofluorescence at postnatal day 5 (P5). The expression of MYO7A showed statistically significant increase in the cochlea of C57BL/6J-+/cir and C57BL/6J-cir/cir mice than that of C57BL/6J-+/+ mice. The MYO7A intensity of the cochlear hair cells also increased in C57BL/6J-+/cir and C57BL/6J-cir/cir mice compared with those of C57BL/6J-+/+ mice. Taken together, the results indicate that Tmie protein may have an important role with MYO7A protein in the development and maintenance of the stereociliary bundles during postnatal developmental stage of the cochlea.
Collapse
|
36
|
|