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Schiel V, Bhattacharya R, Gupta A, Eftekharian K, Xia A, Santa Maria PL. Targeting the NLRP3 inflammasome in cochlear macrophages protects against hearing loss in chronic suppurative otitis media. J Neuroinflammation 2024; 21:223. [PMID: 39277762 PMCID: PMC11402200 DOI: 10.1186/s12974-024-03212-6] [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: 05/08/2024] [Accepted: 08/09/2024] [Indexed: 09/17/2024] Open
Abstract
The activation of the NLRP3 inflammasome has been linked to several inflammatory and autoinflammatory diseases. Despite cases of potential hearing improvement in immune-mediated diseases, direct evidence of the efficacy of targeting this mechanism in the inner ear is still lacking. Previously, we discovered that macrophages are associated with Sensorineural Hearing loss (SNHL) in Chronic Suppurative Otitis Media (CSOM), the leading cause of this permanent hearing loss in the developing world and incurring costs of $4 to $11 billion dollars in the United States. However, the underlying mechanism remained unknown. Here, we investigate how macrophages drive permanent hearing loss in CSOM. We first confirmed the occurrence of NLRP3 inflammasome activation in cochlear macrophages in CSOM. We then revealed that Outer Hair Cells (OHCs) were protected in CSOM by macrophage depletion and subsequently confirmed the same protection in the NLRP3 knockout condition. Furthermore, we showed that therapeutic inhibition of NLRP3 inflammasome activation and downstream inhibition of IL-1β protects OHCs in CSOM. Collectively, our data demonstrates that the main driver for hearing loss in CSOM is NLRP3 inflammasome activation in cochlear macrophages and this is therapeutically targetable, leading the way for the development of interventions to prevent the leading cause of permanent hearing loss and a costly disease in the developed world.
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Affiliation(s)
- Viktoria Schiel
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, Palo Alto, CA, 94305, USA
| | - Ritwija Bhattacharya
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, Palo Alto, CA, 94305, USA
| | - Ankur Gupta
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, Palo Alto, CA, 94305, USA
| | - Kourosh Eftekharian
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, Palo Alto, CA, 94305, USA
| | - Anping Xia
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, Palo Alto, CA, 94305, USA.
| | - Peter L Santa Maria
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, Palo Alto, CA, 94305, USA.
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2
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Gupta A, Schiel V, Bhattacharya R, Eftekharian K, Xia A, Santa Maria PL. Chemokine Receptor CCR2 Is Protective toward Outer Hair Cells in Chronic Suppurative Otitis Media. Immunohorizons 2024; 8:688-694. [PMID: 39264736 DOI: 10.4049/immunohorizons.2400064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2024] [Accepted: 08/21/2024] [Indexed: 09/14/2024] Open
Abstract
Chronic suppurative otitis media (CSOM) is a neglected disease that afflicts 330 million people worldwide and is the most common cause of permanent hearing loss among children in the developing world. Previously, we discovered that outer hair cell (OHC) loss occurred in the basal turn of the cochlea and that macrophages are the major immune cells associated with OHC loss in CSOM. Macrophage-associated cytokines are upregulated. Specifically, CCL-2, an important member of the MCP family, is elevated over time following middle ear infection. CCR2 is a common receptor of the MCP family and the unique receptor of CCL2. CCR2 knockout mice (CCR2-/-) have been used extensively in studies of monocyte activation in neurodegenerative diseases. In the present study, we investigated the effect of CCR2 deletion on the cochlear immune response and OHC survival in CSOM. The OHC survival rate was 84 ± 12.5% in the basal turn of CCR2+/+ CSOM cochleae, compared with was 63 ± 19.9% in the basal turn of CCR2-/- CSOM cochleae (p ≤ 0.05). Macrophage numbers were significantly reduced in CCR2-/- CSOM cochleae compared with CCR2+/+ CSOM cochleae (p ≤ 0.001). In addition, CCL7 was upregulated, whereas IL-33 was downregulated, in CCR2-/- CSOM cochleae. Finally, the permeability of the blood-labyrinth barrier in the stria vascularis remained unchanged in CCR2-/- CSOM compared with CCR2+/+ CSOM. Taken together, the data suggest that CCR2 plays a protective role through cochlear macrophages in the CSOM cochlea.
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MESH Headings
- Animals
- Female
- Male
- Mice
- Chemokine CCL2/metabolism
- Chemokine CCL2/genetics
- Chronic Disease
- Cochlea/metabolism
- Cochlea/pathology
- Cochlea/immunology
- Disease Models, Animal
- Hair Cells, Auditory, Outer/metabolism
- Hair Cells, Auditory, Outer/pathology
- Macrophages/immunology
- Macrophages/metabolism
- Mice, Inbred C57BL
- Mice, Knockout
- Otitis Media, Suppurative/immunology
- Receptors, CCR2/metabolism
- Receptors, CCR2/genetics
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Affiliation(s)
- Ankur Gupta
- Department of Otolaryngology - Head and Neck Surgery, School of Medicine, Stanford University, Palo Alto, CA
| | - Viktoria Schiel
- Department of Otolaryngology - Head and Neck Surgery, School of Medicine, Stanford University, Palo Alto, CA
| | - Ritwija Bhattacharya
- Department of Otolaryngology - Head and Neck Surgery, School of Medicine, Stanford University, Palo Alto, CA
| | - Kourosh Eftekharian
- Department of Otolaryngology - Head and Neck Surgery, School of Medicine, Stanford University, Palo Alto, CA
| | - Anping Xia
- Department of Otolaryngology - Head and Neck Surgery, School of Medicine, Stanford University, Palo Alto, CA
| | - Peter L Santa Maria
- Department of Otolaryngology - Head and Neck Surgery, School of Medicine, Stanford University, Palo Alto, CA
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3
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Pressé MT, Malgrange B, Delacroix L. The cochlear matrisome: Importance in hearing and deafness. Matrix Biol 2024; 125:40-58. [PMID: 38070832 DOI: 10.1016/j.matbio.2023.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/20/2023] [Accepted: 12/06/2023] [Indexed: 02/12/2024]
Abstract
The extracellular matrix (ECM) consists in a complex meshwork of collagens, glycoproteins, and proteoglycans, which serves a scaffolding function and provides viscoelastic properties to the tissues. ECM acts as a biomechanical support, and actively participates in cell signaling to induce tissular changes in response to environmental forces and soluble cues. Given the remarkable complexity of the inner ear architecture, its exquisite structure-function relationship, and the importance of vibration-induced stimulation of its sensory cells, ECM is instrumental to hearing. Many factors of the matrisome are involved in cochlea development, function and maintenance, as evidenced by the variety of ECM proteins associated with hereditary deafness. This review describes the structural and functional ECM components in the auditory organ and how they are modulated over time and following injury.
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Affiliation(s)
- Mary T Pressé
- Developmental Neurobiology Unit, GIGA-Neurosciences, University of Liège, 15 avenue Hippocrate - CHU - B36 (1st floor), Liège B-4000, Belgium
| | - Brigitte Malgrange
- Developmental Neurobiology Unit, GIGA-Neurosciences, University of Liège, 15 avenue Hippocrate - CHU - B36 (1st floor), Liège B-4000, Belgium
| | - Laurence Delacroix
- Developmental Neurobiology Unit, GIGA-Neurosciences, University of Liège, 15 avenue Hippocrate - CHU - B36 (1st floor), Liège B-4000, Belgium.
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4
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Xia A, Udagawa T, Quiñones PM, Atkinson PJ, Applegate BE, Cheng AG, Oghalai JS. The impact of targeted ablation of one row of outer hair cells and Deiters' cells on cochlear amplification. J Neurophysiol 2022; 128:1365-1373. [PMID: 36259670 PMCID: PMC9678430 DOI: 10.1152/jn.00501.2021] [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: 11/15/2021] [Revised: 10/13/2022] [Accepted: 10/17/2022] [Indexed: 11/22/2022] Open
Abstract
The mammalian cochlea contains three rows of outer hair cells (OHCs) that amplify the basilar membrane traveling wave with high gain and exquisite tuning. The pattern of OHC loss caused by typical methods of producing hearing loss in animal models (noise, ototoxic exposure, or aging) is variable and not consistent along the length of the cochlea. Thus, it is difficult to use these approaches to understand how forces from multiple OHCs summate to create normal cochlear amplification. Here, we selectively removed the third row of OHCs and Deiters' cells in adult mice and measured cochlear amplification. In the mature cochlear epithelia, expression of the Wnt target gene Lgr5 is restricted to the third row of Deiters' cells, the supporting cells directly underneath the OHCs. Diphtheria toxin administration to Lgr5DTR-EGFP/+ mice selectively ablated the third row of Deiters' cells and the third row of OHCs. Basilar membrane vibration in vivo demonstrated disproportionately lower reduction in cochlear amplification by about 13.5 dB. On a linear scale, this means that the 33% reduction in OHC number led to a 79% reduction in gain. Thus, these experimental data describe the impact of reducing the force of cochlear amplification by a specific amount. Furthermore, these data argue that because OHC forces progressively and sequentially amplify the traveling wave as it travels to its peak, the loss of even a relatively small number of OHCs, when evenly distributed longitudinally, will cause a substantial reduction in cochlear amplification.NEW & NOTEWORTHY Normal cochlear physiology involves force production from three rows of outer hair cells to amplify and tune the traveling wave. Here, we used a genetic approach to target and ablate the third row of outer hair cells in the mouse cochlea and found it reduced cochlear amplification by 79%. This means that the loss of even a relatively small number of OHCs, when evenly distributed, causes a substantial reduction in cochlear amplification.
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Affiliation(s)
- Anping Xia
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California
| | - Tomokatsu Udagawa
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California
- Department of Otorhinolaryngology, The Jikei University School of Medicine, Tokyo, Japan
| | - Patricia M Quiñones
- Caruso Department of Otolaryngology-Head & Neck Surgery, University of Southern California, Los Angeles, California
| | - Patrick J Atkinson
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California
| | - Brian E Applegate
- Caruso Department of Otolaryngology-Head & Neck Surgery, University of Southern California, Los Angeles, California
- Department of Biomedical Engineering, Denney Research Center (DRB) 140, University of Southern California, Los Angeles, California
| | - Alan G Cheng
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California
| | - John S Oghalai
- Caruso Department of Otolaryngology-Head & Neck Surgery, University of Southern California, Los Angeles, California
- Department of Biomedical Engineering, Denney Research Center (DRB) 140, University of Southern California, Los Angeles, California
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5
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Ebeid M, Barnas K, Zhang H, Yaghmour A, Noreikaite G, Bjork BC. PRDM16 expression and function in mammalian cochlear development. Dev Dyn 2022; 251:1666-1683. [PMID: 35451126 PMCID: PMC9790675 DOI: 10.1002/dvdy.480] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/08/2022] [Accepted: 04/09/2022] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND PR domain containing 16 (PRDM16) is a key transcriptional regulator in the development of craniofacial, adipose, and neural tissues. Our lab identified PRDM16 expression in the epithelial cells of the Kölliker's organ (KO) that starts at ~E13.5 and is maintained until KO disappearance. A transgenic mouse model that carries a gene trap null allele of Prdm16 (Prdm16cGT ) was used to characterize the impact of Prdm16 loss on cochlear development. RESULTS At P0 Prdm16cGT null cochlea exhibited hypoplastic KO, shortened cochlear duct, increased density of hair cells (HCs) and supporting cells (SCs) in the apical turn as well as multiple isolated ectopic HCs within the KO domain. KO epithelial cells proliferation rate was reduced in the apical turn of the developing Prdm16cGT null cochlea vs controls. Bulk RNA sequencing of cochlear duct cells at E14.5 followed by quantitative real time PCR and mRNA Fluorescence in-situ hybridization (FISH) validation identified differentially expressed genes in Prdm16cGT null vs littermate control cochleae. Upregulated genes at E14.5 included Fgf20, as well as several Notch pathway genes (Lfng, Hes1, and Jag1). CONCLUSIONS This study characterizes Prdm16 expression during cochlear development and establishes its requirement for KO development.
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Affiliation(s)
- Michael Ebeid
- College of Graduate Studies, Midwestern UniversityDowners GroveIllinoisUSA,Department of AnatomyMidwestern UniversityDowners GroveIllinoisUSA,Chicago College of Osteopathic MedicineMidwestern UniversityDowners GroveIllinoisUSA
| | - Kathy Barnas
- Biomedical Sciences ProgramMidwestern UniversityDowners GroveIllinoisUSA
| | - Hongji Zhang
- Department of AnatomyMidwestern UniversityDowners GroveIllinoisUSA
| | - Amal Yaghmour
- Biomedical Sciences ProgramMidwestern UniversityDowners GroveIllinoisUSA
| | - Gabriele Noreikaite
- Chicago College of Osteopathic MedicineMidwestern UniversityDowners GroveIllinoisUSA
| | - Bryan C. Bjork
- College of Graduate Studies, Midwestern UniversityDowners GroveIllinoisUSA
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6
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Altoè A, Dewey JB, Charaziak KK, Oghalai JS, Shera CA. Overturning the mechanisms of cochlear amplification via area deformations of the organ of Corti. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2022; 152:2227. [PMID: 36319240 PMCID: PMC9578757 DOI: 10.1121/10.0014794] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 08/17/2022] [Accepted: 09/23/2022] [Indexed: 06/16/2023]
Abstract
The mammalian ear embeds a cellular amplifier that boosts sound-induced hydromechanical waves as they propagate along the cochlea. The operation of this amplifier is not fully understood and is difficult to disentangle experimentally. In the prevailing view, cochlear waves are amplified by the piezo-electric action of the outer hair cells (OHCs), whose cycle-by-cycle elongations and contractions inject power into the local motion of the basilar membrane (BM). Concomitant deformations of the opposing (or "top") side of the organ of Corti are assumed to play a minor role and are generally neglected. However, analysis of intracochlear motions obtained using optical coherence tomography calls this prevailing view into question. In particular, the analysis suggests that (i) the net local power transfer from the OHCs to the BM is either negative or highly inefficient; and (ii) vibration of the top side of the organ of Corti plays a primary role in traveling-wave amplification. A phenomenological model derived from these observations manifests realistic cochlear responses and suggests that amplification arises almost entirely from OHC-induced deformations of the top side of the organ of Corti. In effect, the model turns classic assumptions about spatial impedance relations and power-flow direction within the sensory epithelium upside down.
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Affiliation(s)
- Alessandro Altoè
- Caruso Department of Otolaryngology, University of Southern California, Los Angeles, California 90033, USA
| | - James B Dewey
- Caruso Department of Otolaryngology, University of Southern California, Los Angeles, California 90033, USA
| | - Karolina K Charaziak
- Caruso Department of Otolaryngology, University of Southern California, Los Angeles, California 90033, USA
| | - John S Oghalai
- Caruso Department of Otolaryngology, University of Southern California, Los Angeles, California 90033, USA
| | - Christopher A Shera
- Caruso Department of Otolaryngology, University of Southern California, Los Angeles, California 90033, USA
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7
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Homma K, Takahashi S, Cheatham MA. How much prestin motor activity is required for normal hearing? Hear Res 2022; 423:108376. [PMID: 34848118 PMCID: PMC9091054 DOI: 10.1016/j.heares.2021.108376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 10/07/2021] [Accepted: 10/13/2021] [Indexed: 12/20/2022]
Abstract
Prestin (SLC26A5) is a membrane-based voltage-dependent motor protein responsible for outer hair cell (OHC) somatic electromotility. Its importance for mammalian cochlear amplification has been demonstrated using mouse models lacking prestin (prestin-KO) and expressing dysfunctional prestin, prestinV499G/Y501H (499-prestin-KI). However, it is still not elucidated how prestin contributes to the mechanical amplification process in the cochlea. In this study, we characterized several prestin mouse models in which prestin activity in OHCs was variously manipulated. We found that near-normal cochlear function can be maintained even when prestin activity is significantly reduced, suggesting that the relationship between OHC electromotility and the peripheral sensitivity to sound may not be linear. This result is counterintuitive given the large threshold shifts in prestin-KO and 499-prestin-KI mice, as reported in previous studies. To reconcile these apparently opposing observations, we entertain a voltage- and turgor pressure-based cochlear amplification mechanism that requires prestin but is insensitive to significant reductions in prestin protein expression. This article is part of the Special Issue Outer hair cell Edited by Joseph Santos-Sacchi and Kumar Navaratnam.
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Affiliation(s)
- Kazuaki Homma
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, IL 60208, USA.
| | - Satoe Takahashi
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Mary Ann Cheatham
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, IL 60208, USA; Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA.
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8
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Quiñones PM, Meenderink SWF, Applegate BE, Oghalai JS. Unloading outer hair cell bundles in vivo does not yield evidence of spontaneous oscillations in the mouse cochlea. Hear Res 2022; 423:108473. [PMID: 35287989 PMCID: PMC9339463 DOI: 10.1016/j.heares.2022.108473] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 02/11/2022] [Accepted: 02/28/2022] [Indexed: 12/21/2022]
Abstract
Along with outer hair cell (OHC) somatic electromotility as the actuator of cochlear amplification, active hair bundle motility may be a complementary mechanism in the mammalian auditory system. Here, we searched the mouse cochlea for the presence of spontaneous bundle oscillations that have been observed in non-mammalian ears. In those systems, removal of the overlying membrane is necessary for spontaneous bundle oscillations to manifest. Thus, we used a genetic mouse model with a C1509G (cysteine-to-glycine) point mutation in the Tecta gene where the tectorial (TM) is lifted away from the OHC bundles, allowing us to explore whether unloaded bundles spontaneously oscillate. We used VOCTV in vivo to detect OHC length changes due to electromotility as a proxy for the spontaneous opening and closing of the mechanoelectrical transduction (MET) channels associated with bundle oscillation. In wild type mice with the TM attached to OHC bundles, we did find peaks in vibratory magnitude spectra. Such peaks were not observed in the mutants where the TM is detached from the OHC bundles. Statistical analysis of the time signals indicates that these peaks do not signify active oscillations. Rather, they are filtered responses of the sensitive wild type cochlea to weak background noise. We therefore conclude that, to the limits of our system (∼30 pm), there is no spontaneous mechanical activity that manifests as oscillations in OHC electromotility within the mouse cochlea, arguing that unloaded OHC bundles do not oscillate in vivo. This article is part of the Special Issue Outer hair cell Edited by Joseph Santos-Sacchi and Kumar Navaratnam.
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Affiliation(s)
- Patricia M Quiñones
- Caruso Department of Otolaryngology - Head and Neck Surgery, University of Southern California, Los Angeles, CA, USA
| | | | - Brian E Applegate
- Caruso Department of Otolaryngology - Head and Neck Surgery, University of Southern California, Los Angeles, CA, USA; Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - John S Oghalai
- Caruso Department of Otolaryngology - Head and Neck Surgery, University of Southern California, Los Angeles, CA, USA.
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Razek AAKA, Regal MEE, El-Shabrawi M, Abdeltawwab MM, Megahed A, Elzeny S, Tantawi NE, Taman SE. Diffusion Tensor Imaging of Auditory Pathway in Patients With Crigler-Najjar Syndrome Type I: Correlation With Auditory Brainstem Response. J Child Neurol 2022; 37:119-126. [PMID: 34961382 DOI: 10.1177/08830738211025865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AIM To evaluate the role of diffusion tensor imaging of the auditory pathway in patients with Crigler Najjar syndrome type I and its relation to auditory brainstem response. METHODS Prospective study was done including 12 patients with Crigler Najjar syndrome type I and 10 age- and sex-matched controls that underwent diffusion tensor imaging of brain. Mean diffusivity and fractional anisotropy at 4 regions of the brain and brainstem on each side were measured and correlated with the results of auditory brainstem response for patients. RESULTS There was significantly higher mean diffusivity of cochlear nucleus, superior olivary nucleus, inferior colliculus, and auditory cortex of patients versus controls on both sides for all regions (P = .001). The fractional anisotropy of cochlear nucleus, superior olivary nucleus, inferior colliculus, and auditory cortex of patients versus controls was significantly lower, with P values of, respectively, .001, .001, .003, and .001 on the right side and .001, .001, .003, and .001 on left side, respectively. Also, a negative correlation was found between the maximum bilirubin level and fractional anisotropy of the left superior olivary nucleus and inferior colliculus of both sides. A positive correlation was found between the mean diffusivity and auditory brainstem response wave latency of the right inferior colliculus and left cochlear nucleus. The fractional anisotropy and auditory brainstem response wave latency of the right superior olivary nucleus, left cochlear nucleus, and inferior colliculus of both sides were negatively correlated. CONCLUSION Diffusion tensor imaging can detect microstructural changes in the auditory pathway in Crigler Najjar syndrome type I that can be correlated with auditory brainstem response.
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Affiliation(s)
| | - Mohamed Ezz El Regal
- Gastroenterology and Hepatology Unit, Mansoura Children Hospital, Mansoura Faculty of Medicine, Mansoura, Egypt
| | - Mortada El-Shabrawi
- Faculty of Medicine, Pediatric Hepatology Unit, Pediatric Department, Cairo University, Cairo, Egypt
| | | | - Ahmed Megahed
- Gastroenterology and Hepatology Unit, Mansoura Children Hospital, Mansoura Faculty of Medicine, Mansoura, Egypt
| | - Sherine Elzeny
- Gastroenterology and Hepatology Unit, Mansoura Children Hospital, Mansoura Faculty of Medicine, Mansoura, Egypt
| | - Noha El Tantawi
- Pediatric Neurology Unit, Mansoura Children Hospital, Mansoura Faculty of Medicine, Mansoura, Egypt
| | - Saher Ebrahiem Taman
- Department of Diagnostic Radiology, Mansoura Faculty of Medicine, Mansoura, Egypt
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10
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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: 10] [Impact Index Per Article: 3.3] [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.
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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
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11
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Skuladottir AT, Bjornsdottir G, Nawaz MS, Petersen H, Rognvaldsson S, Moore KHS, Olafsson PI, Magnusson SH, Bjornsdottir A, Sveinsson OA, Sigurdardottir GR, Saevarsdottir S, Ivarsdottir EV, Stefansdottir L, Gunnarsson B, Muhlestein JB, Knowlton KU, Jones DA, Nadauld LD, Hartmann AM, Rujescu D, Strupp M, Walters GB, Thorgeirsson TE, Jonsdottir I, Holm H, Thorleifsson G, Gudbjartsson DF, Sulem P, Stefansson H, Stefansson K. A genome-wide meta-analysis uncovers six sequence variants conferring risk of vertigo. Commun Biol 2021; 4:1148. [PMID: 34620984 PMCID: PMC8497462 DOI: 10.1038/s42003-021-02673-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 09/09/2021] [Indexed: 11/17/2022] Open
Abstract
Vertigo is the leading symptom of vestibular disorders and a major risk factor for falls. In a genome-wide association study of vertigo (Ncases = 48,072, Ncontrols = 894,541), we uncovered an association with six common sequence variants in individuals of European ancestry, including missense variants in ZNF91, OTOG, OTOGL, and TECTA, and a cis-eQTL for ARMC9. The association of variants in ZNF91, OTOGL, and OTOP1 was driven by an association with benign paroxysmal positional vertigo. Using previous reports of sequence variants associating with age-related hearing impairment and motion sickness, we found eight additional variants that associate with vertigo. Although disorders of the auditory and the vestibular system may co-occur, none of the six genome-wide significant vertigo variants were associated with hearing loss and only one was associated with age-related hearing impairment. Our results uncovered sequence variants associating with vertigo in a genome-wide association study and implicated genes with known roles in inner ear development, maintenance, and disease.
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Affiliation(s)
| | | | - Muhammad Sulaman Nawaz
- deCODE genetics/Amgen Inc., Reykjavik, Iceland
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland
| | - Hannes Petersen
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland
- Akureyri Hospital, Akureyri, Iceland
| | | | | | | | | | | | - Olafur A Sveinsson
- Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland
| | | | - Saedis Saevarsdottir
- deCODE genetics/Amgen Inc., Reykjavik, Iceland
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland
- Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland
| | | | | | | | - Joseph B Muhlestein
- Intermountain Medical Center, Intermountain Heart Institute, Salt Lake City, UT, USA
- University of Utah, School of Medicine, Salt Lake City, UT, USA
| | - Kirk U Knowlton
- Intermountain Medical Center, Intermountain Heart Institute, Salt Lake City, UT, USA
- University of Utah, School of Medicine, Salt Lake City, UT, USA
| | - David A Jones
- Precision Genomics, Intermountain Healthcare, Saint George, UT, USA
| | - Lincoln D Nadauld
- Precision Genomics, Intermountain Healthcare, Saint George, UT, USA
- Stanford University, School of Medicine, Stanford, CA, USA
| | - Annette M Hartmann
- Department of Psychiatry, Psychotherapy and Psychosomatics, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Dan Rujescu
- Department of Psychiatry, Psychotherapy and Psychosomatics, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Michael Strupp
- Department of Neurology and German Center for Vertigo and Balance Disorders, Ludwig Maximilians University, Munich, Germany
| | - G Bragi Walters
- deCODE genetics/Amgen Inc., Reykjavik, Iceland
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland
| | | | - Ingileif Jonsdottir
- deCODE genetics/Amgen Inc., Reykjavik, Iceland
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland
| | - Hilma Holm
- deCODE genetics/Amgen Inc., Reykjavik, Iceland
| | | | | | | | | | - Kari Stefansson
- deCODE genetics/Amgen Inc., Reykjavik, Iceland.
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland.
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12
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Badash I, Applegate BE, Oghalai JS. In Vivo Cochlear imaging provides a tool to study endolymphatic hydrops. J Vestib Res 2021; 31:269-276. [PMID: 33136083 DOI: 10.3233/ves-200718] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Exposure to noise trauma, such as that from improvised explosive devices, can lead to sensorineural hearing loss and a reduced quality of life. In order to elucidate the mechanisms underlying noise-induced hearing loss, we have adapted optical coherence tomography (OCT) for real-time cochlear visualization in live mice after blast exposure. We demonstrated that endolymphatic hydrops develops following blast injury, and that this phenomenon may be associated with glutamate excitotoxicity and cochlear synaptopathy. Additionally, osmotic stabilization of endolymphatic hydrops partially rescues cochlear synapses after blast trauma. OCT is thus a valuable research tool for investigating the mechanisms underlying acoustic trauma and dynamic changes in endolymph volume. It may also help with the diagnosis and treatment of human hearing loss and/or vertigo in the near future.
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Affiliation(s)
- Ido Badash
- Caruso Department of Otolaryngology-Head and Neck Surgery, University of Southern California, Los Angeles, CA, USA
| | - Brian E Applegate
- Caruso Department of Otolaryngology-Head and Neck Surgery, University of Southern California, Los Angeles, CA, USA
| | - John S Oghalai
- Caruso Department of Otolaryngology-Head and Neck Surgery, University of Southern California, Los Angeles, CA, USA
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13
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Cheatham MA. Spontaneous otoacoustic emissions are biomarkers for mice with tectorial membrane defects. Hear Res 2021; 409:108314. [PMID: 34332206 DOI: 10.1016/j.heares.2021.108314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 06/22/2021] [Accepted: 07/12/2021] [Indexed: 01/12/2023]
Abstract
Cochlear function depends on the operation of a coupled feedback loop, incorporating outer hair cells (OHCs), and structured to assure that inner hair cells (IHCs) convey frequency specific acoustic information to the brain, even at very low sound levels. Although our knowledge of OHC function and its contribution to cochlear amplification has expanded, the importance of the tectorial membrane (TM) to the processing of mechanical inputs has not been fully elucidated. In addition, there are a surprising number of genetic mutations that affect TM structure and that produce hearing loss in humans. By synthesizing old and new results obtained on several mouse mutants, we learned that animals with abnormal TMs are prone to generate spontaneous otoacoustic emissions (SOAE), which are uncommon in most wildtype laboratory animals. Because SOAEs are not produced in TM mutants or in humans when threshold shifts exceed approximately 25 dB, some degree of cochlear amplification is required. However, amplification by itself is not sufficient because normal mice are rarely spontaneous emitters. Since SOAEs reflect active cochlear operation, TM mutants are valuable for studying the oscillatory nature of the amplification process and the structures associated with its stabilization. Inasmuch as the mouse models were selected to mirror human auditory disorders, using SOAEs as a noninvasive clinical tool may assist the classification of individuals with genetic defects that influence the active mechanisms responsible for sensitivity and frequency selectivity, the hallmarks of mammalian hearing.
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Affiliation(s)
- Mary Ann Cheatham
- The Knowles Hearing Center, Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, 2-240 Frances Searle Building, 2240 Campus Drive, Evanston, IL 60208, USA.
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14
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Abstract
Congenital hearing loss is the most common birth defect, estimated to affect 2-3 in every 1000 births. Currently there is no cure for hearing loss. Treatment options are limited to hearing aids for mild and moderate cases, and cochlear implants for severe and profound hearing loss. Here we provide a literature overview of the environmental and genetic causes of congenital hearing loss, common animal models and methods used for hearing research, as well as recent advances towards developing therapies to treat congenital deafness. © 2021 The Authors.
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Affiliation(s)
- Justine M Renauld
- Department of Otolaryngology, Head & Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Martin L Basch
- Department of Otolaryngology, Head & Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, Ohio.,Department of Genetics and Genome Sciences, Case Western Reserve School of Medicine, Cleveland, Ohio.,Department of Biology, Case Western Reserve University, Cleveland, Ohio.,Department of Otolaryngology, Head & Neck Surgery, University Hospitals, Cleveland, Ohio
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15
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Trouillet A, Miller KK, George SS, Wang P, Ali NES, Ricci A, Grillet N. Loxhd1 Mutations Cause Mechanotransduction Defects in Cochlear Hair Cells. J Neurosci 2021; 41:3331-3343. [PMID: 33707295 PMCID: PMC8051682 DOI: 10.1523/jneurosci.0975-20.2021] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 02/22/2021] [Accepted: 03/02/2021] [Indexed: 12/27/2022] Open
Abstract
Sound detection happens in the inner ear via the mechanical deflection of the hair bundle of cochlear hair cells. The hair bundle is an apical specialization consisting of actin-filled membrane protrusions (called stereocilia) connected by tip links (TLs) that transfer the deflection force to gate the mechanotransduction channels. Here, we identified the hearing loss-associated Loxhd1/DFNB77 gene as being required for the mechanotransduction process. LOXHD1 consists of 15 polycystin lipoxygenase α-toxin (PLAT) repeats, which in other proteins can bind lipids and proteins. LOXHD1 was distributed along the length of the stereocilia. Two LOXHD1 mouse models with mutations in the 10th PLAT repeat exhibited mechanotransduction defects (in both sexes). While mechanotransduction currents in mutant inner hair cells (IHCs) were similar to wild-type levels in the first postnatal week, they were severely affected by postnatal day 11. The onset of the mechanotransduction phenotype was consistent with the temporal progression of postnatal LOXHD1 expression/localization in the hair bundle. The mechanotransduction defect observed in Loxhd1-mutant IHCs was not accompanied by a morphologic defect of the hair bundle or a reduction in TL number. Using immunolocalization, we found that two proteins of the upper and lower TL protein complexes (Harmonin and LHFPL5) were maintained in the mutants, suggesting that the mechanotransduction machinery was present but not activatable. This work identified a novel LOXHD1-dependent step in hair bundle development that is critical for mechanotransduction in mature hair cells as well as for normal hearing function in mice and humans.SIGNIFICANCE STATEMENT Hair cells detect sound-induced forces via the hair bundle, which consists of membrane protrusions connected by tip links. The mechanotransduction machinery forms protein complexes at the tip-link ends. The current study showed that LOXHD1, a multirepeat protein responsible for hearing loss in humans and mice when mutated, was required for hair-cell mechanotransduction, but only after the first postnatal week. Using immunochemistry, we demonstrated that this defect was not caused by the mislocalization of the tip-link complex proteins Harmonin or LHFPL5, suggesting that the mechanotransduction protein complexes were maintained. This work identified a new step in hair bundle development, which is critical for both hair-cell mechanotransduction and hearing.
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Affiliation(s)
- Alix Trouillet
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, Stanford, California 94305
| | - Katharine K Miller
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, Stanford, California 94305
| | - Shefin Sam George
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, Stanford, California 94305
| | - Pei Wang
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, Stanford, California 94305
| | - Noor-E-Seher Ali
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, Stanford, California 94305
| | - Anthony Ricci
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, Stanford, California 94305
- Department of Molecular and Cellular Physiology, School of Medicine, Stanford University, Stanford, California 94305
| | - Nicolas Grillet
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Stanford University, Stanford, California 94305
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16
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Abnormal Tectorial Membranes in Sensorineural Hearing Loss: A Human Temporal Bone Study. Otol Neurotol 2020; 40:e732-e738. [PMID: 31219968 DOI: 10.1097/mao.0000000000002286] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
HYPOTHESIS This study evaluates the morphological changes of the tectorial membrane (TM) in conjunction with degeneration of hair cells, interdental cells, and presence of endolymphatic hydrops (EH) in sensorineural hearing loss (HL) in the human using histopathology techniques. BACKGROUND The TM plays an important role in mechanical transduction of acoustic energy, and pathology of the TM may result in HL. METHODS All temporal bone (TB) specimens from the Massachusetts Eye and Ear Otopathology Laboratory from patients with various causes of sensorineural HL and morphological abnormalities of the TM were evaluated. Cases with a history of cochlear trauma (other than acoustic trauma) and/or severe postmortem artifacts were excluded. The TBs were processed histologically, and the status of hair cells, supporting cells, interdental cells, presence of EH, and postmortem time were tabulated. RESULTS Two thousand two hundred ninety TBs from 1340 individuals were evaluated, and 164 of 748 TBs from the otological disorders in which the TM were abnormal, met the inclusion criteria. The most common disorders were idiopathic sudden deafness (57.1%), genetic etiology (53.7%), and ototoxicity (40.0%), as compared with cases with presbycusis (2.9%). EH was found in 33.3% of all cases with an identified abnormality of the TM.Abnormalities of the TM were 1) deformed, 2) shrunken, 3) detached from the limbus, 4) encapsulated, or 5) missing. Encapsulated, shrunken and missing patterns (36, 35, 31%, respectively) were the most common. CONCLUSION A relative high prevalence of EH among disorders with TM abnormalities suggests a possible common pathophysiology in both. In addition, anatomic abnormalities of the TM may play a role in the pathophysiology of HL in these disorders.
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17
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ElTatawy SS, Elmazzahy EA, El Shennawy AM, Madani HA, Abou Youssef H, Iskander IF. The spectrum of bilirubin neurotoxicity in term and near-term babies with hyperbilirubinemia: Does outcome improve with time? Early Hum Dev 2019; 140:104909. [PMID: 31756691 DOI: 10.1016/j.earlhumdev.2019.104909] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 10/10/2019] [Accepted: 10/15/2019] [Indexed: 12/11/2022]
Abstract
BACKGROUND While neonatal jaundice is generally a common benign condition; severe hyperbilirubinemia has a devastating potential for brain injury. AIM To detect the impact of severe neonatal hyperbilirubinemia on motor and mental development and its progress over time in the first year of life using the Bayley scales of infant development (BSID) II. STUDY DESIGN AND PATIENTS 177 term/near-term infants admitted for neonatal hyperbilirubinemia to the NICU of Cairo University Children's Hospital were enrolled. Clinical examination, BIND score and laboratory tests were performed at admission. Neurodevelopmental assessment using BSIDΙΙ was performed at 3 months for 147/177 neonates, and at 6 months and 12 months for 139/177 neonates. Auditory brainstem evoked potential was recorded at 3 months of age and repeated if abnormal. OUTCOME MEASURES Psychomotor (PDI) and mental developmental indices (MDI) using BSIDII. Auditory impairment using Auditory Brainstem Response (ABR). RESULTS TSB levels ranged from 10 to 63 mg/dL (179.6-1077 μmol/L) with a mean of 25.52 ± 6.5 mg/dL (436 ± 112.9 μmol/L) and BIND scores ranged from 0 to 7. By one year of age, 19/139 patients were affected; 8 had classic kernicterus, 3 had isolated auditory impairment, 1 had severe motor and mild mental delay and 7 had mild motor delay. TSB level and BIND score had positive correlation with auditory impairment and lower scores for PDI (which improved with time) and MDI (which remained stationary). Duration of exposure to hyperbilirubinemia negatively affected neurodevelopmental scores. CONCLUSION The impact of severe hyperbilirubinemia is mainly on motor and auditory impairment. Mild mental delay was detected by BSIDII in few patients. Neurodevelopmental outcome improves over time.
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Affiliation(s)
| | | | | | | | | | - Iman F Iskander
- Cairo University Children's Hospital, Cairo University, Egypt
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18
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Kim DK, Kim JA, Park J, Niazi A, Almishaal A, Park S. The release of surface-anchored α-tectorin, an apical extracellular matrix protein, mediates tectorial membrane organization. SCIENCE ADVANCES 2019; 5:eaay6300. [PMID: 31807709 PMCID: PMC6881170 DOI: 10.1126/sciadv.aay6300] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 10/02/2019] [Indexed: 06/10/2023]
Abstract
The tectorial membrane (TM) is an apical extracellular matrix (ECM) that hovers over the cochlear sensory epithelium and plays an essential role in auditory transduction. The TM forms facing the luminal endolymph-filled space and exhibits complex ultrastructure. Contrary to the current extracellular assembly model, which posits that secreted collagen fibrils and ECM components self-arrange in the extracellular space, we show that surface tethering of α-tectorin (TECTA) via a glycosylphosphatidylinositol anchor is essential to prevent diffusion of secreted TM components. In the absence of surface-tethered TECTA, collagen fibrils aggregate randomly and fail to recruit TM glycoproteins. Conversely, conversion of TECTA into a transmembrane form results in a layer of collagens on the epithelial surface that fails to form a multilayered structure. We propose a three-dimensional printing model for TM morphogenesis: A new layer of ECM is printed on the cell surface concomitant with the release of a preestablished layer to generate the multilayered TM.
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Affiliation(s)
- Dong-Kyu Kim
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Ju Ang Kim
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Joosang Park
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Ava Niazi
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Ali Almishaal
- Department of Communication Sciences and Disorders, University of Utah, Salt Lake City, UT 84112, USA
| | - Sungjin Park
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
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19
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Sellon JB, Ghaffari R, Freeman DM. The Tectorial Membrane: Mechanical Properties and Functions. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a033514. [PMID: 30348837 DOI: 10.1101/cshperspect.a033514] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The tectorial membrane (TM) is widely believed to play a critical role in determining the remarkable sensitivity and frequency selectivity that are hallmarks of mammalian hearing. Recently developed mouse models of human hearing disorders have provided new insights into the molecular, nanomechanical mechanisms that underlie resonance and traveling wave properties of the TM. Herein we review recent experimental and theoretical results detailing TM morphology, local poroelastic and electromechanical interactions, and global spread of excitation via TM traveling waves, with direct implications for cochlear mechanisms.
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Affiliation(s)
- Jonathan B Sellon
- Research Laboratory of Electronics, MIT, Cambridge, Massachusetts 02139
| | - Roozbeh Ghaffari
- Research Laboratory of Electronics, MIT, Cambridge, Massachusetts 02139
| | - Dennis M Freeman
- Research Laboratory of Electronics, MIT, Cambridge, Massachusetts 02139.,Department of Electrical Engineering and Computer Science, MIT, Cambridge, Massachusetts 02139
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20
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Dong W, Xia A, Raphael PD, Puria S, Applegate B, Oghalai JS. Organ of Corti vibration within the intact gerbil cochlea measured by volumetric optical coherence tomography and vibrometry. J Neurophysiol 2018; 120:2847-2857. [PMID: 30281386 DOI: 10.1152/jn.00702.2017] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
There is indirect evidence that the mammalian cochlea in the low-frequency apical and the more commonly studied high-frequency basal regions function in fundamentally different ways. Here, we directly tested this hypothesis by measuring sound-induced vibrations of the organ of Corti (OoC) at three turns of the gerbil cochlea using volumetric optical coherence tomography vibrometry (VOCTV), an approach that permits noninvasive imaging through the bone. In the apical turn, there was little frequency selectivity, and the displacement-vs.-frequency curves had low-pass filter characteristics with a corner frequency of ~0.5-0.9 kHz. The vibratory magnitudes increased compressively with increasing stimulus intensity at all frequencies. In the middle turn, responses were similar except for a slight peak in the response at ~2.5 kHz. The gain was ~50 dB at the peak and 30-40 dB at lower frequencies. In the basal turn, responses were sharply tuned and compressively nonlinear, consistent with observations in the literature. These data demonstrated that there is a transition of the mechanical response of the OoC along the length of the cochlea such that frequency tuning is sharper in the base than in the apex. Because the responses are fundamentally different, it is not appropriate to simply frequency shift vibratory data measured at one cochlear location to predict the cochlear responses at other locations. Furthermore, this means that the number of hair cells stimulated by sound is larger for low-frequency stimuli and smaller for high-frequency stimuli for the same intensity level. Thus the mechanisms of central processing of sounds must vary with frequency. NEW & NOTEWORTHY A volumetric optical coherence tomography and vibrometry system was used to probe cochlear mechanics within the intact gerbil cochlea. We found a gradual transition of the mechanical response of the organ of Corti along the length of the cochlea such that tuning at the base is dramatically sharper than that at the apex. These data help to explain discrepancies in the literature regarding how the cochlea processes low-frequency sounds.
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Affiliation(s)
- Wei Dong
- VA Loma Linda Healthcare System, Loma Linda, California.,Department of Otolaryngology - Head and Neck Surgery, Loma Linda University Health , Loma Linda, California
| | - Anping Xia
- Department of Otolaryngology - Head and Neck Surgery, Stanford University , Stanford, California
| | - Patrick D Raphael
- Department of Otolaryngology - Head and Neck Surgery, Stanford University , Stanford, California
| | - Sunil Puria
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary and Harvard Medical School , Boston, Massachusetts
| | - Brian Applegate
- Department of Biomedical Engineering, Texas A&M University , College Station, Texas
| | - John S Oghalai
- Caruso Department of Otolaryngology - Head and Neck Surgery, University of Southern California , Los Angeles, California
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21
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Dewey JB, Xia A, Müller U, Belyantseva IA, Applegate BE, Oghalai JS. Mammalian Auditory Hair Cell Bundle Stiffness Affects Frequency Tuning by Increasing Coupling along the Length of the Cochlea. Cell Rep 2018; 23:2915-2927. [PMID: 29874579 PMCID: PMC6309882 DOI: 10.1016/j.celrep.2018.05.024] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/24/2018] [Accepted: 05/08/2018] [Indexed: 01/15/2023] Open
Abstract
The stereociliary bundles of cochlear hair cells convert mechanical vibrations into the electrical signals required for auditory sensation. While the stiffness of the bundles strongly influences mechanotransduction, its influence on the vibratory response of the cochlear partition is unclear. To assess this, we measured cochlear vibrations in mutant mice with reduced bundle stiffness or with a tectorial membrane (TM) that is detached from the sensory epithelium. We found that reducing bundle stiffness decreased the high-frequency extent and sharpened the tuning of vibratory responses obtained postmortem. Detaching the TM further reduced the high-frequency extent of the vibrations but also lowered the partition's resonant frequency. Together, these results demonstrate that the bundle's stiffness and attachment to the TM contribute to passive longitudinal coupling in the cochlea. We conclude that the stereociliary bundles and TM interact to facilitate passive-wave propagation to more apical locations, possibly enhancing active-wave amplification in vivo.
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Affiliation(s)
- James B Dewey
- The Caruso Department of Otolaryngology - Head & Neck Surgery, University of Southern California, Los Angeles, CA 90033, USA
| | - Anping Xia
- Department of Otolaryngology - Head & Neck Surgery, Stanford University, Stanford, CA 94305, USA
| | - Ulrich Müller
- The Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | | | - Brian E Applegate
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - John S Oghalai
- The Caruso Department of Otolaryngology - Head & Neck Surgery, University of Southern California, Los Angeles, CA 90033, USA.
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22
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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.
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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
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23
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Kim J, Xia A, Grillet N, Applegate BE, Oghalai JS. Osmotic stabilization prevents cochlear synaptopathy after blast trauma. Proc Natl Acad Sci U S A 2018; 115:E4853-E4860. [PMID: 29735658 PMCID: PMC6003510 DOI: 10.1073/pnas.1720121115] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Traumatic noise causes hearing loss by damaging sensory hair cells and their auditory synapses. There are no treatments. Here, we investigated mice exposed to a blast wave approximating a roadside bomb. In vivo cochlear imaging revealed an increase in the volume of endolymph, the fluid within scala media, termed endolymphatic hydrops. Endolymphatic hydrops, hair cell loss, and cochlear synaptopathy were initiated by trauma to the mechanosensitive hair cell stereocilia and were K+-dependent. Increasing the osmolality of the adjacent perilymph treated endolymphatic hydrops and prevented synaptopathy, but did not prevent hair cell loss. Conversely, inducing endolymphatic hydrops in control mice by lowering perilymph osmolality caused cochlear synaptopathy that was glutamate-dependent, but did not cause hair cell loss. Thus, endolymphatic hydrops is a surrogate marker for synaptic bouton swelling after hair cells release excitotoxic levels of glutamate. Because osmotic stabilization prevents neural damage, it is a potential treatment to reduce hearing loss after noise exposure.
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Affiliation(s)
- Jinkyung Kim
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, CA 94305
| | - Anping Xia
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, CA 94305
| | - Nicolas Grillet
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, CA 94305
| | - Brian E Applegate
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843
| | - John S Oghalai
- Caruso Department of Otolaryngology-Head and Neck Surgery, University of Southern California, Los Angeles, CA 90033
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24
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Goodyear RJ, Richardson GP. Structure, Function, and Development of the Tectorial Membrane: An Extracellular Matrix Essential for Hearing. Curr Top Dev Biol 2018; 130:217-244. [PMID: 29853178 DOI: 10.1016/bs.ctdb.2018.02.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The tectorial membrane is an extracellular matrix that lies over the apical surface of the auditory epithelia in the inner ears of reptiles, birds, and mammals. Recent studies have shown it is composed of a small set of proteins, some of which are only produced at high levels in the ear and many of which are the products of genes that, when mutated, cause nonsyndromic forms of human hereditary deafness. Quite how the proteins of the tectorial membrane are assembled within the lumen of the inner ear to form a structure that is precisely regulated in its size and physical properties along the length of a tonotopically organized hearing organ is a question that remains to be fully answered. In this brief review we will summarize what is known thus far about the structure, protein composition, and function of the tectorial membrane in birds and mammals, describe how the tectorial membrane develops, and discuss major events that have occurred during the evolution of this extracellular matrix.
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Affiliation(s)
- Richard J Goodyear
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Guy P Richardson
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom.
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25
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Yamamoto N, Mutai H, Namba K, Morita N, Masuda S, Nishi Y, Nakano A, Masuda S, Fujioka M, Kaga K, Ogawa K, Matsunaga T. Prevalence of TECTA mutation in patients with mid-frequency sensorineural hearing loss. Orphanet J Rare Dis 2017; 12:157. [PMID: 28946916 PMCID: PMC5613382 DOI: 10.1186/s13023-017-0708-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 09/07/2017] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND To date, 102 genes have been reported as responsible for non-syndromic hearing loss, some of which are associated with specific audiogram features. Four genes have been reported as causative for mid-frequency sensorineural hearing loss (MFSNHL), among which TECTA is the most frequently reported; however, the prevalence of TECTA mutations is unknown. To elucidate the prevalence of TECTA mutation in MFSNHL and clarify genotype-phenotype correlations, we analyzed the genetic and clinical features of patients with MFSNHL. METHODS Subjects with bilateral non-syndromic hearing loss were prescreened for GJB2 and m.1555A > G and m.3243A > G mitochondrial DNA mutations, and patients with inner ear malformations were excluded. We selected MFSNHL patients whose audiograms met the U-shaped criterion proposed by the GENDEAF study group, along with those with shallow U-shaped audiograms, for TECTA analysis. All TECTA exons were analyzed by Sanger sequencing. Novel missense variants were classified as possibly pathogenic, non-pathogenic, and variants of uncertain significance, based on genetic data. To evaluate novel possibly pathogenic variants, we predicted changes in protein structure by molecular modeling. RESULTS Pathogenic and possibly pathogenic variants of TECTA were found in 4 (6.0%) of 67 patients with MFSNHL. In patients with U-shaped audiograms, none (0%) of 21 had pathogenic or possibly pathogenic variants. In patients with shallow U-shaped audiograms, four (8.7%) of 46 had pathogenic or possibly pathogenic variants. Two novel possibly pathogenic variants were identified and two previously reported mutations were considered as variant of unknown significance. The clinical features of patients with pathogenic and possibly pathogenic variants were consistent with those in previous studies. Pathogenic or possibly pathogenic variants were identified in 3 of 23 families (13.0%) which have the family histories compatible with autosomal dominant and 1 of 44 families (2.3%) which have the family histories compatible with sporadic or autosomal recessive. CONCLUSIONS TECTA mutations were identified in 6.0% of MFSNHL. These mutations were more frequent in patients with shallow U-shaped audiograms than those with U-shaped audiograms, and in families which have the family histories compatible with autosomal dominant than those with the family histories compatible with sporadic or autosomal recessive.
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Affiliation(s)
- Nobuko Yamamoto
- Department of Otolaryngology, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo, 152-8902, Japan.,Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo, 152-8902, Japan.,Department of Otolaryngology, Head and Neck Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan
| | - Hideki Mutai
- Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo, 152-8902, Japan
| | - Kazunori Namba
- Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo, 152-8902, Japan
| | - Noriko Morita
- Department of Otolaryngology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi, Tokyo, 173-8606, Japan
| | - Shin Masuda
- Department of Pediatric Rehabilitation, Hiroshima Prefectural Hospital, 1-5-54 Ujina-Kanda, Minami, Hiroshima, 734-8530, Japan
| | - Yasuyuki Nishi
- Department of Otolaryngology, National Hospital Organization Kure Medical Center, 3-1 Aoyama, Kure, Hiroshima, 737-0023, Japan
| | - Atsuko Nakano
- Division of Otorhinolaryngology, Chiba Children's Hospital, 579-1 Heta, Midori, Chiba, 266-0007, Japan
| | - Sawako Masuda
- Department of Otorhinolaryngology, National Mie Hospital, 357 Osato-Kubota, Tsu, Mie, 514-0125, Japan
| | - Masato Fujioka
- Department of Otolaryngology, Head and Neck Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan
| | - Kimitaka Kaga
- Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo, 152-8902, Japan
| | - Kaoru Ogawa
- Department of Otolaryngology, Head and Neck Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan
| | - Tatsuo Matsunaga
- Department of Otolaryngology, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo, 152-8902, Japan. .,Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo, 152-8902, Japan.
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Neuroplastin Isoform Np55 Is Expressed in the Stereocilia of Outer Hair Cells and Required for Normal Outer Hair Cell Function. J Neurosci 2017; 36:9201-16. [PMID: 27581460 DOI: 10.1523/jneurosci.0093-16.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Accepted: 07/14/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Neuroplastin (Nptn) is a member of the Ig superfamily and is expressed in two isoforms, Np55 and Np65. Np65 regulates synaptic transmission but the function of Np55 is unknown. In an N-ethyl-N-nitrosaurea mutagenesis screen, we have now generated a mouse line with an Nptn mutation that causes deafness. We show that Np55 is expressed in stereocilia of outer hair cells (OHCs) but not inner hair cells and affects interactions of stereocilia with the tectorial membrane. In vivo vibrometry demonstrates that cochlear amplification is absent in Nptn mutant mice, which is consistent with the failure of OHC stereocilia to maintain stable interactions with the tectorial membrane. Hair bundles show morphological defects as the mutant mice age and while mechanotransduction currents can be evoked in early postnatal hair cells, cochlea microphonics recordings indicate that mechanontransduction is affected as the mutant mice age. We thus conclude that differential splicing leads to functional diversification of Nptn, where Np55 is essential for OHC function, while Np65 is implicated in the regulation of synaptic function. SIGNIFICANCE STATEMENT Amplification of input sound signals, which is needed for the auditory sense organ to detect sounds over a wide intensity range, depends on mechanical coupling of outer hair cells to the tectorial membrane. The current study shows that neuroplastin, a member of the Ig superfamily, which has previously been linked to the regulation of synaptic plasticity, is critical to maintain a stable mechanical link of outer hair cells with the tectorial membrane. In vivo recordings demonstrate that neuroplastin is essential for sound amplification and that mutation in neuroplastin leads to auditory impairment in mice.
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27
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Two-Dimensional Cochlear Micromechanics Measured In Vivo Demonstrate Radial Tuning within the Mouse Organ of Corti. J Neurosci 2017; 36:8160-73. [PMID: 27488636 DOI: 10.1523/jneurosci.1157-16.2016] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 06/07/2016] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED The exquisite sensitivity and frequency discrimination of mammalian hearing underlie the ability to understand complex speech in noise. This requires force generation by cochlear outer hair cells (OHCs) to amplify the basilar membrane traveling wave; however, it is unclear how amplification is achieved with sharp frequency tuning. Here we investigated the origin of tuning by measuring sound-induced 2-D vibrations within the mouse organ of Corti in vivo Our goal was to determine the transfer function relating the radial shear between the structures that deflect the OHC bundle, the tectorial membrane and reticular lamina, to the transverse motion of the basilar membrane. We found that, after normalizing their responses to the vibration of the basilar membrane, the radial vibrations of the tectorial membrane and reticular lamina were tuned. The radial tuning peaked at a higher frequency than transverse basilar membrane tuning in the passive, postmortem condition. The radial tuning was similar in dead mice, indicating that this reflected passive, not active, mechanics. These findings were exaggerated in Tecta(C1509G/C1509G) mice, where the tectorial membrane is detached from OHC stereocilia, arguing that the tuning of radial vibrations within the hair cell epithelium is distinct from tectorial membrane tuning. Together, these results reveal a passive, frequency-dependent contribution to cochlear filtering that is independent of basilar membrane filtering. These data argue that passive mechanics within the organ of Corti sharpen frequency selectivity by defining which OHCs enhance the vibration of the basilar membrane, thereby tuning the gain of cochlear amplification. SIGNIFICANCE STATEMENT Outer hair cells amplify the traveling wave within the mammalian cochlea. The resultant gain and frequency sharpening are necessary for speech discrimination, particularly in the presence of background noise. Here we measured the 2-D motion of the organ of Corti in mice and found that the structures that stimulate the outer hair cell stereocilia, the tectorial membrane and reticular lamina, were sharply tuned in the radial direction. Radial tuning was similar in dead mice and in mice lacking a tectorial membrane. This suggests that radial tuning comes from passive mechanics within the hair cell epithelium, and that these mechanics, at least in part, may tune the gain of cochlear amplification.
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28
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Recio-Spinoso A, Oghalai JS. Mechanical tuning and amplification within the apex of the guinea pig cochlea. J Physiol 2017; 595:4549-4561. [PMID: 28382742 DOI: 10.1113/jp273881] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 03/28/2017] [Indexed: 12/21/2022] Open
Abstract
KEY POINTS A popular conception of mammalian cochlear physiology is that tuned mechanical vibration of the basilar membrane defines the frequency response of the innervating auditory nerve fibres However, the data supporting these concepts come from vibratory measurements at cochlear locations tuned to high frequencies (>7 kHz). Here, we measured the travelling wave in regions of the guinea pig cochlea that respond to low frequencies (<2 kHz) and found that mechanical tuning was broad and did not match auditory nerve tuning characteristics. Non-linear amplification of the travelling wave functioned over a broad frequency range and did not substantially sharpen frequency tuning. Thus, the neural encoding of low-frequency sounds, which includes most of the information conveyed by human speech, is not principally determined by basilar membrane mechanics. ABSTRACT The popular notion of mammalian cochlear function is that auditory nerves are tuned to respond best to different sound frequencies because basilar membrane vibration is mechanically tuned to different frequencies along its length. However, this concept has only been demonstrated in regions of the cochlea tuned to frequencies >7 kHz, not in regions sensitive to lower frequencies where human speech is encoded. Here, we overcame historical technical limitations and non-invasively measured sound-induced vibrations at four locations distributed over the apical two turns of the guinea pig cochlea. In turn 3, the responses demonstrated low-pass filter characteristics. In turn 2, the responses were low-pass-like, in that they occasionally did have a slight peak near the corner frequency. The corner frequencies of the responses were tonotopically tuned and ranged from 384 to 668 Hz. Non-linear gain, or amplification of the vibrations in response to low-intensity stimuli, was found both below and above the corner frequencies. Post mortem, cochlear gain disappeared. The non-linear gain was typically 10-30 dB and was broad-band rather than sharply tuned. However, the gain did reach nearly 50 dB in turn 2 for higher stimulus frequencies, nearly the amount of gain found in basal cochlear regions. Thus, our data prove that mechanical responses do not match neural responses and that cochlear amplification does not appreciably sharpen frequency tuning for cochlear regions that respond to frequencies <2 kHz. These data indicate that the non-linear processing of sound performed by the guinea pig cochlea varies substantially between the cochlear apex and base.
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Affiliation(s)
- Alberto Recio-Spinoso
- Instituto de Investigación en Discapacidades Neurológicas, Universidad de Castilla-La Mancha, Albacete, Spain
| | - John S Oghalai
- Deparment of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, USA
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29
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Xia A, Liu X, Raphael PD, Applegate BE, Oghalai JS. Hair cell force generation does not amplify or tune vibrations within the chicken basilar papilla. Nat Commun 2016; 7:13133. [PMID: 27796310 PMCID: PMC5095595 DOI: 10.1038/ncomms13133] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 09/07/2016] [Indexed: 12/22/2022] Open
Abstract
Frequency tuning within the auditory papilla of most non-mammalian species is electrical, deriving from ion-channel resonance within their sensory hair cells. In contrast, tuning within the mammalian cochlea is mechanical, stemming from active mechanisms within outer hair cells that amplify the basilar membrane travelling wave. Interestingly, hair cells in the avian basilar papilla demonstrate both electrical resonance and force-generation, making it unclear which mechanism creates sharp frequency tuning. Here, we measured sound-induced vibrations within the apical half of the chicken basilar papilla in vivo and found broadly-tuned travelling waves that were not amplified. However, distortion products were found in live but not dead chickens. These findings support the idea that avian hair cells do produce force, but that their effects on vibration are small and do not sharpen tuning. Therefore, frequency tuning within the apical avian basilar papilla is not mechanical, and likely derives from hair cell electrical resonance. The avian auditory papilla has many similarities to the mammalian cochlea but whether force generation by hair cells amplifies the travelling wave, as it does in mammals, remains unknown. Here the authors show that the chicken basilar papilla does not have a ‘cochlear amplifier' and that sharp frequency tuning does not derive from mechanical vibrations.
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Affiliation(s)
- Anping Xia
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, California 94305, USA
| | - Xiaofang Liu
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, California 94305, USA.,Department of Anorectal Surgery, the First Affiliated hospital of China Medical University, 155 NanjingBei Street, ShenYang, LiaoNing Province 110001, China
| | - Patrick D Raphael
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, California 94305, USA
| | - Brian E Applegate
- Department of Biomedical Engineering, Texas A&M University, 5059 Emerging Technology Building, 3120 TAMU, College Station, Texas 77843, USA
| | - John S Oghalai
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, California 94305, USA
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30
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Carpinelli MR, Kruse EA, Arhatari BD, Debrincat MA, Ogier JM, Bories JC, Kile BT, Burt RA. Mice Haploinsufficient for Ets1 and Fli1 Display Middle Ear Abnormalities and Model Aspects of Jacobsen Syndrome. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 185:1867-76. [PMID: 26093983 DOI: 10.1016/j.ajpath.2015.03.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 02/01/2015] [Accepted: 03/02/2015] [Indexed: 12/23/2022]
Abstract
E26 transformation-specific 1 (ETS1) and friend leukemia integration 1 (FLI1) are members of the ETS family of transcription factors, of which there are 28 in humans. Both genes are hemizygous in Jacobsen syndrome, an 11q contiguous gene deletion disorder involving thrombocytopenia, facial dysmorphism, growth and mental retardation, malformation of the heart and other organs, and hearing impairment associated with recurrent ear infections. To determine whether any of these defects are because of hemizygosity for ETS1 and FLI1, we characterized the phenotype of mice heterozygous for mutant alleles of Ets1 and Fli1. Fli1(+/-) mice displayed mild thrombocytopenia, as did Ets1(+/-)Fli1(+/-) animals. Fli1(+/-) and Ets1(+/-)Fli1(+/-) mice also displayed craniofacial abnormalities, including a small middle ear cavity, short nasal bone, and malformed interface between the nasal bone process and cartilaginous nasal septum. They exhibited hearing impairment, otitis media, fusions of ossicles to the middle ear wall, and deformed stapes. Hearing impairment was more penetrant and stapes malformations were more severe in Ets1(+/-)Fli1(+/-) mice than in Fli1(+/-) mice, indicating partial functional redundancy of these transcription factors during auditory development. Our findings indicate that the short nose, otitis media, and hearing impairment in Jacobsen syndrome are likely because of hemizygosity for ETS1 and FLI1.
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Affiliation(s)
- Marina R Carpinelli
- Murdoch Childrens Research Institute, Parkville, Victoria, Australia; HEARing Cooperative Research Centre, University of Melbourne, Melbourne, Victoria, Australia
| | - Elizabeth A Kruse
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Benedicta D Arhatari
- Department of Physics, ARC Centre of Excellence for Coherent X-Ray Science, La Trobe University, Bundoora, Victoria, Australia
| | - Marlyse A Debrincat
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Jacqueline M Ogier
- Murdoch Childrens Research Institute, Parkville, Victoria, Australia; HEARing Cooperative Research Centre, University of Melbourne, Melbourne, Victoria, Australia
| | | | - Benjamin T Kile
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Rachel A Burt
- Murdoch Childrens Research Institute, Parkville, Victoria, Australia; HEARing Cooperative Research Centre, University of Melbourne, Melbourne, Victoria, Australia; Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Genetics, University of Melbourne, Melbourne, Victoria, Australia.
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Abstract
Although hyperbilirubinemia is extremely common among neonates and is usually mild and transient, it sometimes leads to bilirubin-induced neurologic damage (BIND). The auditory pathway is highly sensitive to the effects of elevated total serum/plasma bilirubin (TB) levels, with damage manifesting clinically as auditory neuropathy spectrum disorder. Compared to full-term neonates, preterm neonates are more susceptible to BIND and suffer adverse effects at lower TB levels with worse long-term outcomes. Furthermore, although standardized guidelines for management of hyperbilirubinemia exist for term and late preterm neonates, similar guidelines for neonates less than 35 weeks gestational age are limited.
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Affiliation(s)
- Cristen Olds
- Department of Otolaryngology - Head and Neck Surgery, Stanford University, 801 Welch Road, CA 94305, USA
| | - John S Oghalai
- Department of Otolaryngology - Head and Neck Surgery, Stanford University, 801 Welch Road, CA 94305, USA.
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32
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Basch ML, Brown RM, Jen H, Groves AK. Where hearing starts: the development of the mammalian cochlea. J Anat 2016; 228:233-54. [PMID: 26052920 PMCID: PMC4718162 DOI: 10.1111/joa.12314] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2015] [Indexed: 12/11/2022] Open
Abstract
The mammalian cochlea is a remarkable sensory organ, capable of perceiving sound over a range of 10(12) in pressure, and discriminating both infrasonic and ultrasonic frequencies in different species. The sensory hair cells of the mammalian cochlea are exquisitely sensitive, responding to atomic-level deflections at speeds on the order of tens of microseconds. The number and placement of hair cells are precisely determined during inner ear development, and a large number of developmental processes sculpt the shape, size and morphology of these cells along the length of the cochlear duct to make them optimally responsive to different sound frequencies. In this review, we briefly discuss the evolutionary origins of the mammalian cochlea, and then describe the successive developmental processes that lead to its induction, cell cycle exit, cellular patterning and the establishment of topologically distinct frequency responses along its length.
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Affiliation(s)
- Martin L. Basch
- Department of NeuroscienceBaylor College of MedicineHoustonTXUSA
| | - Rogers M. Brown
- Program in Developmental BiologyBaylor College of MedicineHoustonTXUSA
| | - Hsin‐I Jen
- Program in Developmental BiologyBaylor College of MedicineHoustonTXUSA
| | - Andrew K. Groves
- Department of NeuroscienceBaylor College of MedicineHoustonTXUSA
- Program in Developmental BiologyBaylor College of MedicineHoustonTXUSA
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonTXUSA
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33
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Ren T, He W, Barr-Gillespie PG. Reverse transduction measured in the living cochlea by low-coherence heterodyne interferometry. Nat Commun 2016; 7:10282. [PMID: 26732830 PMCID: PMC4729828 DOI: 10.1038/ncomms10282] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 11/25/2015] [Indexed: 12/27/2022] Open
Abstract
It is generally believed that the remarkable sensitivity and frequency selectivity of mammalian hearing depend on outer hair cell-generated force, which amplifies sound-induced vibrations inside the cochlea. This 'reverse transduction' force production has never been demonstrated experimentally, however, in the living ear. Here by directly measuring microstructure vibrations inside the cochlear partition using a custom-built interferometer, we demonstrate that electrical stimulation can evoke both fast broadband and slow sharply tuned responses of the reticular lamina, but only a slow tuned response of the basilar membrane. Our results indicate that outer hair cells can generate sufficient force to drive the reticular lamina over all audible frequencies in living cochleae. Contrary to expectations, the cellular force causes a travelling wave rather than an immediate local vibration of the basilar membrane; this travelling wave vibrates in phase with the reticular lamina at the best frequency, and results in maximal vibration at the apical ends of outer hair cells.
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Affiliation(s)
- Tianying Ren
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Wenxuan He
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Peter G. Barr-Gillespie
- Oregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, Portland, Oregon 97239, USA
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34
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Song Y, Xia A, Lee HY, Wang R, Ricci AJ, Oghalai JS. Activity-dependent regulation of prestin expression in mouse outer hair cells. J Neurophysiol 2015; 113:3531-42. [PMID: 25810486 DOI: 10.1152/jn.00869.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 03/19/2015] [Indexed: 12/11/2022] Open
Abstract
Prestin is a membrane protein necessary for outer hair cell (OHC) electromotility and normal hearing. Its regulatory mechanisms are unknown. Several mouse models of hearing loss demonstrate increased prestin, inspiring us to investigate how hearing loss might feedback onto OHCs. To test whether centrally mediated feedback regulates prestin, we developed a novel model of inner hair cell loss. Injection of diphtheria toxin (DT) into adult CBA mice produced significant loss of inner hair cells without affecting OHCs. Thus, DT-injected mice were deaf because they had no afferent auditory input despite OHCs continuing to receive normal auditory mechanical stimulation and having normal function. Patch-clamp experiments demonstrated no change in OHC prestin, indicating that loss of information transfer centrally did not alter prestin expression. To test whether local mechanical feedback regulates prestin, we used Tecta(C1509G) mice, where the tectorial membrane is malformed and only some OHCs are stimulated. OHCs connected to the tectorial membrane had normal prestin levels, whereas OHCs not connected to the tectorial membrane had elevated prestin levels, supporting an activity-dependent model. To test whether the endocochlear potential was necessary for prestin regulation, we studied Tecta(C1509G) mice at different developmental ages. OHCs not connected to the tectorial membrane had lower than normal prestin levels before the onset of the endocochlear potential and higher than normal prestin levels after the onset of the endocochlear potential. Taken together, these data indicate that OHC prestin levels are regulated through local feedback that requires mechanoelectrical transduction currents. This adaptation may serve to compensate for variations in the local mechanical environment.
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Affiliation(s)
- Yohan Song
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
| | - Anping Xia
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
| | - Hee Yoon Lee
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
| | - Rosalie Wang
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
| | - Anthony J Ricci
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
| | - John S Oghalai
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California
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35
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Noninvasive in vivo imaging reveals differences between tectorial membrane and basilar membrane traveling waves in the mouse cochlea. Proc Natl Acad Sci U S A 2015; 112:3128-33. [PMID: 25737536 DOI: 10.1073/pnas.1500038112] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Sound is encoded within the auditory portion of the inner ear, the cochlea, after propagating down its length as a traveling wave. For over half a century, vibratory measurements to study cochlear traveling waves have been made using invasive approaches such as laser Doppler vibrometry. Although these studies have provided critical information regarding the nonlinear processes within the living cochlea that increase the amplitude of vibration and sharpen frequency tuning, the data have typically been limited to point measurements of basilar membrane vibration. In addition, opening the cochlea may alter its function and affect the findings. Here we describe volumetric optical coherence tomography vibrometry, a technique that overcomes these limitations by providing depth-resolved displacement measurements at 200 kHz inside a 3D volume of tissue with picometer sensitivity. We studied the mouse cochlea by imaging noninvasively through the surrounding bone to measure sound-induced vibrations of the sensory structures in vivo, and report, to our knowledge, the first measures of tectorial membrane vibration within the unopened cochlea. We found that the tectorial membrane sustains traveling wave propagation. Compared with basilar membrane traveling waves, tectorial membrane traveling waves have larger dynamic ranges, sharper frequency tuning, and apically shifted positions of peak vibration. These findings explain discrepancies between previously published basilar membrane vibration and auditory nerve single unit data. Because the tectorial membrane directly overlies the inner hair cell stereociliary bundles, these data provide the most accurate characterization of the stimulus shaping the afferent auditory response available to date.
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36
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Abstract
Hyperbilirubinemia occurs commonly in neonates and is usually mild and transient, with no long-lasting sequelae. However, bilirubin-induced neurologic damage may occur in some infants. The auditory pathway is the most sensitive part of the central nervous system to bilirubin-induced toxicity, and permanent sequelae may result from only moderately elevated total serum/plasma bilirubin levels. The damage to the auditory system occurs primarily within the brainstem and cranial nerve VIII, and manifests clinically as auditory neuropathy spectrum disorder.
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Affiliation(s)
- Cristen Olds
- Department of Otolaryngology - Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305-5739, USA
| | - John S Oghalai
- Department of Otolaryngology - Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305-5739, USA.
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37
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Jones GP, Elliott SJ, Russell IJ, Lukashkin AN. Modified protein expression in the tectorial membrane of the cochlea reveals roles for the striated sheet matrix. Biophys J 2015; 108:203-10. [PMID: 25564867 PMCID: PMC4286592 DOI: 10.1016/j.bpj.2014.11.1854] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 11/04/2014] [Accepted: 11/04/2014] [Indexed: 11/28/2022] Open
Abstract
The tectorial membrane (TM) of the mammalian cochlea is a complex extracellular matrix which, in response to acoustic stimulation, displaces the hair bundles of outer hair cells (OHCs), thereby initiating sensory transduction and amplification. Here, using TM segments from the basal, high-frequency region of the cochleae of genetically modified mice (including models of human hereditary deafness) with missing or modified TM proteins, we demonstrate that frequency-dependent stiffening is associated with the striated sheet matrix (SSM). Frequency-dependent stiffening largely disappeared in all three TM mutations studied where the SSM was absent either entirely or at least from the stiffest part of the TM overlying the OHCs. In all three TM mutations, dissipation of energy is decreased at low (<8 kHz) and increased at high (>8 kHz) stimulus frequencies. The SSM is composed of polypeptides carrying fixed charges, and electrostatic interaction between them may account for frequency-dependent stiffness changes in the material properties of the TM. Through comparison with previous in vivo measurements, it is proposed that implementation of frequency-dependent stiffening of the TM in the OHC attachment region facilitates interaction among tones, backward transmission of energy, and amplification in the cochlea.
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Affiliation(s)
- Gareth P Jones
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom
| | - Stephen J Elliott
- Institute of Sound and Vibration Research, University of Southampton, Southampton, United Kingdom
| | - Ian J Russell
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom.
| | - Andrei N Lukashkin
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom.
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38
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Sellon JB, Ghaffari R, Farrahi S, Richardson GP, Freeman DM. Porosity controls spread of excitation in tectorial membrane traveling waves. Biophys J 2014; 106:1406-13. [PMID: 24655516 DOI: 10.1016/j.bpj.2014.02.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 02/05/2014] [Accepted: 02/06/2014] [Indexed: 11/18/2022] Open
Abstract
Cochlear frequency selectivity plays a key role in our ability to understand speech, and is widely believed to be associated with cochlear amplification. However, genetic studies targeting the tectorial membrane (TM) have demonstrated both sharper and broader tuning with no obvious changes in hair bundle or somatic motility mechanisms. For example, cochlear tuning of Tectb(-/-) mice is significantly sharper than that of Tecta(Y1870C/+) mice, even though TM stiffnesses are similarly reduced relative to wild-type TMs. Here we show that differences in TM viscosity can account for these differences in tuning. In the basal cochlear turn, nanoscale pores of Tecta(Y1870C/+) TMs are significantly larger than those of Tectb(-/-) TMs. The larger pore size reduces shear viscosity (by ∼70%), thereby reducing traveling wave speed and increasing spread of excitation. These results demonstrate the previously unrecognized importance of TM porosity in cochlear and neural tuning.
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Affiliation(s)
- Jonathan B Sellon
- Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Cambridge, Massachusetts; Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Roozbeh Ghaffari
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Shirin Farrahi
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Guy P Richardson
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom
| | - Dennis M Freeman
- Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Cambridge, Massachusetts; Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts.
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39
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Kim AR, Chang MY, Koo JW, Oh SH, Choi BY. Novel TECTA mutations identified in stable sensorineural hearing loss and their clinical implications. Audiol Neurootol 2014; 20:17-25. [PMID: 25413827 DOI: 10.1159/000366514] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Accepted: 08/08/2014] [Indexed: 11/19/2022] Open
Abstract
TECTA is a causative gene of autosomal dominant (DFNA8/A12) and autosomal recessive (DFNB 21) nonsyndromic sensorineural hearing loss (NSHL). Mutations in TECTA account for 4% of all autosomal dominant NSHL cases in some populations and are thus thought to be one of the major causes of autosomal dominant NSHL. A genotype-phenotype correlation for autosomal dominant mutations in the TECTA gene has been proposed. Two families (SB146 and SB149), which segregated moderate NSHL in an autosomal dominant fashion, were included in this study. We performed targeted resequencing of 134 known deafness genes (TRS-134) and bioinformatics analyses to find causative mutations for NSHL in these 2 families. Through TRS-134, we detected 2 novel mutations, i.e. c.3995G>T (p.C1332F) and c.5618C>T (p.T1873I), in the TECTA gene. These mutations cosegregated with NSHL in the studied families and were not detected in normal controls. The mutations c.3995G>T and c.5618C>T reside in the von Willebrand factor type D3-D4 (vWFD3-D4) interdomain of the zonadhesin (ZA) domain and the zona pellucida (ZP) domain, respectively. p.C1332F is the first mutation detected in the vWFD3-D4 interdomain of the ZA domain. The mutations p.C1332F and p.T1873I were associated with stable high-frequency and mid-frequency hearing loss, respectively. Notably, the cysteine residue mutated to phenylalanine in SB146 was not related to progression of sensorineural hearing loss, which argues against the previous hypothesis. Here we confirm a known genotype-phenotype correlation for the ZP domain and propose a hypothetical genotype-phenotype correlation which relates mutations in vWFD3-D4 to stable high-frequency NSHL in Koreans. This clinical feature makes subjects with the missense mutation in the vWFD3-D4 interdomain of TECTA potentially good candidates for middle ear implantation.
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Affiliation(s)
- Ah Reum Kim
- Department of Otorhinolaryngology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, South Korea
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40
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Loss of the tectorial membrane protein CEACAM16 enhances spontaneous, stimulus-frequency, and transiently evoked otoacoustic emissions. J Neurosci 2014; 34:10325-38. [PMID: 25080593 DOI: 10.1523/jneurosci.1256-14.2014] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
α-Tectorin (TECTA), β-tectorin (TECTB), and carcinoembryonic antigen-related cell adhesion molecule 16 (CEACAM) are secreted glycoproteins that are present in the tectorial membrane (TM), an extracellular structure overlying the hearing organ of the inner ear, the organ of Corti. Previous studies have shown that TECTA and TECTB are both required for formation of the striated-sheet matrix within which collagen fibrils of the TM are imbedded and that CEACAM16 interacts with TECTA. To learn more about the structural and functional significance of CEACAM16, we created a Ceacam16-null mutant mouse. In the absence of CEACAM16, TECTB levels are reduced, a clearly defined striated-sheet matrix does not develop, and Hensen's stripe, a prominent feature in the basal two-thirds of the TM in WT mice, is absent. CEACAM16 is also shown to interact with TECTB, indicating that it may stabilize interactions between TECTA and TECTB. Although brain-stem evoked responses and distortion product otoacoustic emissions are, for most frequencies, normal in young mice lacking CEACAM16, stimulus-frequency and transiently evoked emissions are larger. We also observed spontaneous otoacoustic emissions (SOAEs) in 70% of the homozygous mice. This incidence is remarkable considering that <3% of WT controls have SOAEs. The predominance of SOAEs >15 kHz correlates with the loss of Hensen's stripe. Results from mice lacking CEACAM16 are consistent with the idea that the organ of Corti evolved to maximize the gain of the cochlear amplifier while preventing large oscillations. Changes in TM structure appear to influence the balance between energy generation and dissipation such that the system becomes unstable.
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41
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Gao SS, Wang R, Raphael PD, Moayedi Y, Groves AK, Zuo J, Applegate BE, Oghalai JS. Vibration of the organ of Corti within the cochlear apex in mice. J Neurophysiol 2014; 112:1192-204. [PMID: 24920025 DOI: 10.1152/jn.00306.2014] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The tonotopic map of the mammalian cochlea is commonly thought to be determined by the passive mechanical properties of the basilar membrane. The other tissues and cells that make up the organ of Corti also have passive mechanical properties; however, their roles are less well understood. In addition, active forces produced by outer hair cells (OHCs) enhance the vibration of the basilar membrane, termed cochlear amplification. Here, we studied how these biomechanical components interact using optical coherence tomography, which permits vibratory measurements within tissue. We measured not only classical basilar membrane tuning curves, but also vibratory responses from the rest of the organ of Corti within the mouse cochlear apex in vivo. As expected, basilar membrane tuning was sharp in live mice and broad in dead mice. Interestingly, the vibratory response of the region lateral to the OHCs, the "lateral compartment," demonstrated frequency-dependent phase differences relative to the basilar membrane. This was sharply tuned in both live and dead mice. We then measured basilar membrane and lateral compartment vibration in transgenic mice with targeted alterations in cochlear mechanics. Prestin(499/499), Prestin(-/-), and Tecta(C1509G/C1509G) mice demonstrated no cochlear amplification but maintained the lateral compartment phase difference. In contrast, Sfswap(Tg/Tg) mice maintained cochlear amplification but did not demonstrate the lateral compartment phase difference. These data indicate that the organ of Corti has complex micromechanical vibratory characteristics, with passive, yet sharply tuned, vibratory characteristics associated with the supporting cells. These characteristics may tune OHC force generation to produce the sharp frequency selectivity of mammalian hearing.
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Affiliation(s)
- Simon S Gao
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California; Department of Bioengineering, Rice University, Houston, Texas
| | - Rosalie Wang
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California
| | - Patrick D Raphael
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California
| | - Yalda Moayedi
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas
| | - Andrew K Groves
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas; Program in Developmental Biology, Baylor College of Medicine, Houston, Texas
| | - Jian Zuo
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee; and
| | - Brian E Applegate
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas
| | - John S Oghalai
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, California;
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42
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Bai H, Yang X, Temuribagen, Guilan, Suyalatu, Narisu, Wu H, Chen Y, Liu Y, Wu Q. A rare novel mutation in TECTA causes autosomal dominant nonsyndromic hearing loss in a Mongolian family. BMC MEDICAL GENETICS 2014; 15:34. [PMID: 25008054 PMCID: PMC3994966 DOI: 10.1186/1471-2350-15-34] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Accepted: 03/12/2014] [Indexed: 12/16/2022]
Abstract
Background The genetic basis of autosomal dominant nonsyndromic hearing loss is complex. Genetic factors are responsible for approximately 50% of cases with congenital hearing loss. However, no previous studies have documented the clinical phenotype and genetic basis of autosomal dominant nonsyndromic hearing loss in Mongolians. Methods In this study, we performed exon capture sequencing of a Mongolian family with hereditary hearing loss and identified a novel mutation in TECTA gene, which encodes α -tectorin, a major component of the inner ear extracellular matrix that contacts the specialized sensory hair cells. Results The novel G → T missense mutation at nucleotide 6016 results in a substitution of amino acid aspartate at 2006 with tyrosine (Asp2006Tyr) in a highly conserved zona pellucida (ZP) domain of α-tectorin. The mutation is not found in control subjects from the same family with normal hearing and a genotype-phenotype correlation is observed. Conclusion A novel missense mutation c.6016 G > T (p.Asp2006Tyr) of TECTA gene is a characteristic TECTA-related mutation which causes autosomal dominant nonsyndromic hearing loss. Our result indicated that mutation in TECTA gene is responsible for the hearing loss in this Mongolian family.
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43
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The candidate splicing factor Sfswap regulates growth and patterning of inner ear sensory organs. PLoS Genet 2014; 10:e1004055. [PMID: 24391519 PMCID: PMC3879212 DOI: 10.1371/journal.pgen.1004055] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 11/08/2013] [Indexed: 12/15/2022] Open
Abstract
The Notch signaling pathway is thought to regulate multiple stages of inner ear development. Mutations in the Notch signaling pathway cause disruptions in the number and arrangement of hair cells and supporting cells in sensory regions of the ear. In this study we identify an insertional mutation in the mouse Sfswap gene, a putative splicing factor, that results in mice with vestibular and cochlear defects that are consistent with disrupted Notch signaling. Homozygous Sfswap mutants display hyperactivity and circling behavior consistent with vestibular defects, and significantly impaired hearing. The cochlea of newborn Sfswap mutant mice shows a significant reduction in outer hair cells and supporting cells and ectopic inner hair cells. This phenotype most closely resembles that seen in hypomorphic alleles of the Notch ligand Jagged1 (Jag1). We show that Jag1; Sfswap compound mutants have inner ear defects that are more severe than expected from simple additive effects of the single mutants, indicating a genetic interaction between Sfswap and Jag1. In addition, expression of genes involved in Notch signaling in the inner ear are reduced in Sfswap mutants. There is increased interest in how splicing affects inner ear development and function. Our work is one of the first studies to suggest that a putative splicing factor has specific effects on Notch signaling pathway members and inner ear development.
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44
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Xia A, Song Y, Wang R, Gao SS, Clifton W, Raphael P, Chao SI, Pereira FA, Groves AK, Oghalai JS. Prestin regulation and function in residual outer hair cells after noise-induced hearing loss. PLoS One 2013; 8:e82602. [PMID: 24376553 PMCID: PMC3869702 DOI: 10.1371/journal.pone.0082602] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 10/25/2013] [Indexed: 12/27/2022] Open
Abstract
The outer hair cell (OHC) motor protein prestin is necessary for electromotility, which drives cochlear amplification and produces exquisitely sharp frequency tuning. TectaC1509G transgenic mice have hearing loss, and surprisingly have increased OHC prestin levels. We hypothesized, therefore, that prestin up-regulation may represent a generalized response to compensate for a state of hearing loss. In the present study, we sought to determine the effects of noise-induced hearing loss on prestin expression. After noise exposure, we performed cytocochleograms and observed OHC loss only in the basal region of the cochlea. Next, we patch clamped OHCs from the apical turn (9–12 kHz region), where no OHCs were lost, in noise-exposed and age-matched control mice. The non-linear capacitance was significantly higher in noise-exposed mice, consistent with higher functional prestin levels. We then measured prestin protein and mRNA levels in whole-cochlea specimens. Both Western blot and qPCR studies demonstrated increased prestin expression after noise exposure. Finally, we examined the effect of the prestin increase in vivo following noise damage. Immediately after noise exposure, ABR and DPOAE thresholds were elevated by 30–40 dB. While most of the temporary threshold shifts recovered within 3 days, there were additional improvements over the next month. However, DPOAE magnitudes, basilar membrane vibration, and CAP tuning curve measurements from the 9–12 kHz cochlear region demonstrated no differences between noise-exposed mice and control mice. Taken together, these data indicate that prestin is up-regulated by 32–58% in residual OHCs after noise exposure and that the prestin is functional. These findings are consistent with the notion that prestin increases in an attempt to partially compensate for reduced force production because of missing OHCs. However, in regions where there is no OHC loss, the cochlea is able to compensate for the excess prestin in order to maintain stable auditory thresholds and frequency discrimination.
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MESH Headings
- Animals
- Cochlear Microphonic Potentials
- Evoked Potentials, Auditory, Brain Stem
- Gene Expression Regulation
- Hair Cells, Auditory, Outer/metabolism
- Hair Cells, Auditory, Outer/pathology
- Hearing Loss, Noise-Induced/metabolism
- Hearing Loss, Noise-Induced/pathology
- Hearing Loss, Noise-Induced/physiopathology
- Mice
- Models, Biological
- Molecular Motor Proteins/genetics
- Molecular Motor Proteins/metabolism
- Noise
- Otoacoustic Emissions, Spontaneous
- Patch-Clamp Techniques
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
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Affiliation(s)
- Anping Xia
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Yohan Song
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Rosalie Wang
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Simon S. Gao
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
- Department of Bioengineering, Rice University, Houston, Texas, United States of America
| | - Will Clifton
- Bobby R. Alford Department of Otolaryngology – Head and Neck Surgery, Baylor College of Medicine, Houston, Texas, United States of America
| | - Patrick Raphael
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Sung-il Chao
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
- Department of Otolaryngology–Head and Neck Surgery, Chosun University, Gwangju, South Korea
| | - Fred A. Pereira
- Bobby R. Alford Department of Otolaryngology – Head and Neck Surgery, Baylor College of Medicine, Houston, Texas, United States of America
| | - Andrew K. Groves
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - John S. Oghalai
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
- * E-mail:
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Legan PK, Goodyear RJ, Morín M, Mencia A, Pollard H, Olavarrieta L, Korchagina J, Modamio-Hoybjor S, Mayo F, Moreno F, Moreno-Pelayo MA, Richardson GP. Three deaf mice: mouse models for TECTA-based human hereditary deafness reveal domain-specific structural phenotypes in the tectorial membrane. Hum Mol Genet 2013; 23:2551-68. [PMID: 24363064 PMCID: PMC3990158 DOI: 10.1093/hmg/ddt646] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Tecta is a modular, non-collagenous protein of the tectorial membrane (TM), an extracellular matrix of the cochlea essential for normal hearing. Missense mutations in Tecta cause dominant forms of non-syndromic deafness and a genotype-phenotype correlation has been reported in humans, with mutations in different Tecta domains causing mid- or high-frequency hearing impairments that are either stable or progressive. Three mutant mice were created as models for human Tecta mutations; the Tecta(L1820F,G1824D/+) mouse for zona pellucida (ZP) domain mutations causing stable mid-frequency hearing loss in a Belgian family, the Tecta(C1837G/+) mouse for a ZP-domain mutation underlying progressive mid-frequency hearing loss in a Spanish family and the Tecta(C1619S/+) mouse for a zonadhesin-like (ZA) domain mutation responsible for progressive, high-frequency hearing loss in a French family. Mutations in the ZP and ZA domains generate distinctly different changes in the structure of the TM. Auditory brainstem response thresholds in the 8-40 kHz range are elevated by 30-40 dB in the ZP-domain mutants, whilst those in the ZA-domain mutant are elevated by 20-30 dB. The phenotypes are stable and no evidence has been found for a progressive deterioration in TM structure or auditory function. Despite elevated auditory thresholds, the Tecta mutant mice all exhibit an enhanced tendency to have audiogenic seizures in response to white noise stimuli at low sound pressure levels (≤84 dB SPL), revealing a previously unrecognised consequence of Tecta mutations. These results, together with those from previous studies, establish an allelic series for Tecta unequivocally demonstrating an association between genotype and phenotype.
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Affiliation(s)
- P Kevin Legan
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
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46
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Probst FJ, Corrigan RR, del Gaudio D, Salinger AP, Lorenzo I, Gao SS, Chiu I, Xia A, Oghalai JS, Justice MJ. A point mutation in the gene for asparagine-linked glycosylation 10B (Alg10b) causes nonsyndromic hearing impairment in mice (Mus musculus). PLoS One 2013; 8:e80408. [PMID: 24303013 PMCID: PMC3841196 DOI: 10.1371/journal.pone.0080408] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 10/02/2013] [Indexed: 01/10/2023] Open
Abstract
The study of mouse hearing impairment mutants has led to the identification of a number of human hearing impairment genes and has greatly furthered our understanding of the physiology of hearing. The novel mouse mutant neurological/sensory 5 (nse5) demonstrates a significantly reduced or absent startle response to sound and is therefore a potential murine model of human hearing impairment. Genetic analysis of 500 intercross progeny localized the mutant locus to a 524 kilobase (kb) interval on mouse chromosome 15. A missense mutation in a highly-conserved amino acid was found in the asparagine-linked glycosylation 10B gene (Alg10b), which is within the critical interval for the nse5 mutation. A 20.4 kb transgene containing a wildtype copy of the Alg10b gene rescued the mutant phenotype in nse5/nse5 homozygous animals, confirming that the mutation in Alg10b is responsible for the nse5/nse5 mutant phenotype. Homozygous nse5/nse5 mutants had abnormal auditory brainstem responses (ABRs), distortion product otoacoustic emissions (DPOAEs), and cochlear microphonics (CMs). Endocochlear potentials (EPs), on the other hand, were normal. ABRs and DPOAEs also confirmed the rescue of the mutant nse5/nse5 phenotype by the wildtype Alg10b transgene. These results suggested a defect in the outer hair cells of mutant animals, which was confirmed by histologic analysis. This is the first report of mutation in a gene involved in the asparagine (N)-linked glycosylation pathway causing nonsyndromic hearing impairment, and it suggests that the hearing apparatus, and the outer hair cells in particular, are exquisitely sensitive to perturbations of the N-linked glycosylation pathway.
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Affiliation(s)
- Frank J. Probst
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Rebecca R. Corrigan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Daniela del Gaudio
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Andrew P. Salinger
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Isabel Lorenzo
- Genetically Engineered Mouse Shared Resource, Baylor College of Medicine, Houston, Texas, United States of America
| | - Simon S. Gao
- Department of Bioengineering, Rice University, Houston, Texas, United States of America
| | - Ilene Chiu
- Department of Otolaryngology-Head and Neck Surgery, Baylor College of Medicine, Houston, Texas, United States of America
| | - Anping Xia
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - John S. Oghalai
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Monica J. Justice
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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47
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Cho SI, Gao SS, Xia A, Wang R, Salles FT, Raphael PD, Abaya H, Wachtel J, Baek J, Jacobs D, Rasband MN, Oghalai JS. Mechanisms of hearing loss after blast injury to the ear. PLoS One 2013; 8:e67618. [PMID: 23840874 PMCID: PMC3698122 DOI: 10.1371/journal.pone.0067618] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 05/20/2013] [Indexed: 12/21/2022] Open
Abstract
Given the frequent use of improvised explosive devices (IEDs) around the world, the study of traumatic blast injuries is of increasing interest. The ear is the most common organ affected by blast injury because it is the body's most sensitive pressure transducer. We fabricated a blast chamber to re-create blast profiles similar to that of IEDs and used it to develop a reproducible mouse model to study blast-induced hearing loss. The tympanic membrane was perforated in all mice after blast exposure and found to heal spontaneously. Micro-computed tomography demonstrated no evidence for middle ear or otic capsule injuries; however, the healed tympanic membrane was thickened. Auditory brainstem response and distortion product otoacoustic emission threshold shifts were found to be correlated with blast intensity. As well, these threshold shifts were larger than those found in control mice that underwent surgical perforation of their tympanic membranes, indicating cochlear trauma. Histological studies one week and three months after the blast demonstrated no disruption or damage to the intra-cochlear membranes. However, there was loss of outer hair cells (OHCs) within the basal turn of the cochlea and decreased spiral ganglion neurons (SGNs) and afferent nerve synapses. Using our mouse model that recapitulates human IED exposure, our results identify that the mechanisms underlying blast-induced hearing loss does not include gross membranous rupture as is commonly believed. Instead, there is both OHC and SGN loss that produce auditory dysfunction.
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Affiliation(s)
- Sung-Il Cho
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
- Department of Otolaryngology–Head and Neck Surgery, Chosun University, Gwangju, South Korea
| | - Simon S. Gao
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
- Department of Bioengineering, Rice University, Houston, Texas, United States of America
| | - Anping Xia
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Rosalie Wang
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Felipe T. Salles
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Patrick D. Raphael
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Homer Abaya
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Jacqueline Wachtel
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Jongmin Baek
- Department of Computer Science, Stanford University, Stanford, California, United States of America
| | - David Jacobs
- Department of Computer Science, Stanford University, Stanford, California, United States of America
| | - Matthew N. Rasband
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - John S. Oghalai
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
- * E-mail:
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48
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Jones GP, Lukashkina VA, Russell IJ, Elliott SJ, Lukashkin AN. Frequency-dependent properties of the tectorial membrane facilitate energy transmission and amplification in the cochlea. Biophys J 2013; 104:1357-66. [PMID: 23528095 DOI: 10.1016/j.bpj.2013.02.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 01/29/2013] [Accepted: 02/07/2013] [Indexed: 10/27/2022] Open
Abstract
The remarkable sensitivity, frequency selectivity, and dynamic range of the mammalian cochlea relies on longitudinal transmission of minuscule amounts of energy as passive, pressure-driven, basilar membrane (BM) traveling waves. These waves are actively amplified at frequency-specific locations by a mechanism that involves interaction between the BM and another extracellular matrix, the tectorial membrane (TM). From mechanical measurements of isolated segments of the TM, we made the important new (to our knowledge) discovery that the stiffness of the TM is reduced when it is mechanically stimulated at physiologically relevant magnitudes and at frequencies below their frequency place in the cochlea. The reduction in stiffness functionally uncouples the TM from the organ of Corti, thereby minimizing energy losses during passive traveling-wave propagation. Stiffening and decreased viscosity of the TM at high stimulus frequencies can potentially facilitate active amplification, especially in the high-frequency, basal turn, where energy loss due to internal friction within the TM is less than in the apex. This prediction is confirmed by neural recordings from several frequency regions of the cochlea.
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Affiliation(s)
- G P Jones
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom
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49
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Kim BJ, Zaveri HP, Shchelochkov OA, Yu Z, Hernández-García A, Seymour ML, Oghalai JS, Pereira FA, Stockton DW, Justice MJ, Lee B, Scott DA. An allelic series of mice reveals a role for RERE in the development of multiple organs affected in chromosome 1p36 deletions. PLoS One 2013; 8:e57460. [PMID: 23451234 PMCID: PMC3581587 DOI: 10.1371/journal.pone.0057460] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 01/24/2013] [Indexed: 01/28/2023] Open
Abstract
Individuals with terminal and interstitial deletions of chromosome 1p36 have a spectrum of defects that includes eye anomalies, postnatal growth deficiency, structural brain anomalies, seizures, cognitive impairment, delayed motor development, behavior problems, hearing loss, cardiovascular malformations, cardiomyopathy, and renal anomalies. The proximal 1p36 genes that contribute to these defects have not been clearly delineated. The arginine-glutamic acid dipeptide (RE) repeats gene (RERE) is located in this region and encodes a nuclear receptor coregulator that plays a critical role in embryonic development as a positive regulator of retinoic acid signaling. Rere-null mice die of cardiac failure between E9.5 and E11.5. This limits their usefulness in studying the role of RERE in the latter stages of development and into adulthood. To overcome this limitation, we created an allelic series of RERE-deficient mice using an Rere-null allele, om, and a novel hypomorphic Rere allele, eyes3 (c.578T>C, p.Val193Ala), which we identified in an N-ethyl-N-nitrosourea (ENU)-based screen for autosomal recessive phenotypes. Analyses of these mice revealed microphthalmia, postnatal growth deficiency, brain hypoplasia, decreased numbers of neuronal nuclear antigen (NeuN)-positive hippocampal neurons, hearing loss, cardiovascular malformations–aortic arch anomalies, double outlet right ventricle, and transposition of the great arteries, and perimembranous ventricular septal defects–spontaneous development of cardiac fibrosis and renal agenesis. These findings suggest that RERE plays a critical role in the development and function of multiple organs including the eye, brain, inner ear, heart and kidney. It follows that haploinsufficiency of RERE may contribute–alone or in conjunction with other genetic, environmental, or stochastic factors–to the development of many of the phenotypes seen in individuals with terminal and interstitial deletions that include the proximal region of chromosome 1p36.
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Affiliation(s)
- Bum Jun Kim
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Hitisha P. Zaveri
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Oleg A. Shchelochkov
- Department of Pediatrics, The University of Iowa, Iowa City, Iowa, United States of America
| | - Zhiyin Yu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Andrés Hernández-García
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Michelle L. Seymour
- Huffington Center on Aging and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - John S. Oghalai
- Department of Otolaryngology-Head and Neck Surgery, Stanford School of Medicine, Stanford, California, United State of America
| | - Fred A. Pereira
- Huffington Center on Aging and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Otolaryngology–Head and Neck Surgery, Baylor College of Medicine, Houston, Texas, United States of America
| | - David W. Stockton
- Departments of Pediatrics and Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Monica J. Justice
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Brendan Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
| | - Daryl A. Scott
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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50
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Gao SS, Raphael PD, Wang R, Park J, Xia A, Applegate BE, Oghalai JS. In vivo vibrometry inside the apex of the mouse cochlea using spectral domain optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2013. [PMID: 23411442 DOI: 10.1364/boe.4.000230] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Sound transduction within the auditory portion of the inner ear, the cochlea, is a complex nonlinear process. The study of cochlear mechanics in large rodents has provided important insights into cochlear function. However, technological and experimental limitations have restricted studies in mice due to their smaller cochlea. These challenges are important to overcome because of the wide variety of transgenic mouse strains with hearing loss mutations that are available for study. To accomplish this goal, we used spectral domain optical coherence tomography to visualize and measure sound-induced vibrations of intracochlear tissues. We present, to our knowledge, the first vibration measurements from the apex of an unopened mouse cochlea.
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Affiliation(s)
- Simon S Gao
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305, USA ; Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX 77005, USA
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