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Mansour A, Sellon JB, Filizzola D, Ghaffari R, Cheatham MA, Freeman DM. Age-related degradation of tectorial membrane dynamics with loss of CEACAM16. Biophys J 2021; 120:4777-4785. [PMID: 34555361 PMCID: PMC8595744 DOI: 10.1016/j.bpj.2021.09.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 06/01/2021] [Accepted: 09/16/2021] [Indexed: 11/29/2022] Open
Abstract
Studies of genetic disorders of sensorineural hearing loss have been instrumental in delineating mechanisms that underlie the remarkable sensitivity and selectivity that are hallmarks of mammalian hearing. For example, genetic modifications of TECTA and TECTB, which are principal proteins that comprise the tectorial membrane (TM), have been shown to alter auditory thresholds and frequency tuning in ways that can be understood in terms of changes in the mechanical properties of the TM. Here, we investigate effects of genetic modification targeting CEACAM16, a third important TM protein. Loss of CEACAM16 has been recently shown to lead to progressive reductions in sensitivity. Whereas age-related hearing losses have previously been linked to changes in sensory receptor cells, the role of the TM in progressive hearing loss is largely unknown. Here, we show that TM stiffness and viscosity are significantly reduced in adult mice that lack functional CEACAM16 relative to age-matched wild-type controls. By contrast, these same mechanical properties of TMs from juvenile mice that lack functional CEACAM16 are more similar to those of wild-type mice. Thus, changes in hearing phenotype align with changes in TM material properties and can be understood in terms of the same TM wave properties that were previously used to characterize modifications of TECTA and TECTB. These results demonstrate that CEACAM16 is essential for maintaining TM mechanical and wave properties, which in turn are necessary for sustaining the remarkable sensitivity and selectivity of mammalian hearing with increasing age.
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Affiliation(s)
- Amer Mansour
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Jonathan B Sellon
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Daniel Filizzola
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Roozbeh Ghaffari
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Mary Ann Cheatham
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Knowles Hearing Center, Northwestern University, Evanston, Illinois
| | - Dennis M Freeman
- 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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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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Booth KT, Kahrizi K, Najmabadi H, Azaiez H, Smith RJ. Old gene, new phenotype: splice-altering variants in CEACAM16 cause recessive non-syndromic hearing impairment. J Med Genet 2018; 55:555-560. [PMID: 29703829 PMCID: PMC6060001 DOI: 10.1136/jmedgenet-2018-105349] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/03/2018] [Accepted: 04/07/2018] [Indexed: 12/14/2022]
Abstract
BACKGROUND Hearing loss is a genetically and phenotypically heterogeneous disorder. OBJECTIVES The purpose of this study was to determine the genetic cause underlying the postlingual progressive hearing loss in two Iranian families. METHODS We used OtoSCOPE, a next-generation sequencing platform targeting >150 genes causally linked to deafness, to screen two deaf probands. Data analysis was completed using a custom bioinformatics pipeline, and variants were functionally assessed using minigene splicing assays. RESULTS We identified two homozygous splice-altering variants (c.37G>T and c.662-1G>C) in the CEACAM16 gene, segregating with the deafness in each family. The minigene splicing results revealed the c.37G>T results in complete skipping of exon 2 and loss of the AUG start site. The c.662-1G>C activates a cryptic splice site inside exon 5 resulting in a shift in the mRNA reading frame. CONCLUSIONS These results suggest that loss-of-function mutations in CEACAM16 result in postlingual progressive hearing impairment and further support the role of CEACAM16 in auditory function.
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Affiliation(s)
- Kevin T Booth
- Molecular Otolaryngology Renal Research Laboratories, Department of Otolaryngology-Head Neck Surgery, University of Iowa, Iowa City, Iowa
- The Interdisciplinary Graduate Program in Molecular Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Kimia Kahrizi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Hossein Najmabadi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Hela Azaiez
- Molecular Otolaryngology Renal Research Laboratories, Department of Otolaryngology-Head Neck Surgery, University of Iowa, Iowa City, Iowa
| | - Richard J Smith
- Molecular Otolaryngology Renal Research Laboratories, Department of Otolaryngology-Head Neck Surgery, University of Iowa, Iowa City, Iowa
- The Interdisciplinary Graduate Program in Molecular Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa
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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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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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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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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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Abstract
The tectorial membrane (TM) clearly plays a mechanical role in stimulating cochlear sensory receptors, but the presence of fixed charge in TM constituents suggests that electromechanical properties also may be important. Here, we measure the fixed charge density of the TM and show that this density of fixed charge is sufficient to affect mechanical properties and to generate electrokinetic motions. In particular, alternating currents applied to the middle and marginal zones of isolated TM segments evoke motions at audio frequencies (1-1,000 Hz). Electrically evoked motions are nanometer scaled (∼5-900 nm), decrease with increasing stimulus frequency, and scale linearly over a broad range of electric field amplitudes (0.05-20 kV/m). These findings show that the mammalian TM is highly charged and suggest the importance of a unique TM electrokinetic mechanism.
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Gavara N, Manoussaki D, Chadwick RS. Auditory mechanics of the tectorial membrane and the cochlear spiral. Curr Opin Otolaryngol Head Neck Surg 2011; 19:382-7. [PMID: 21785353 PMCID: PMC3327783 DOI: 10.1097/moo.0b013e32834a5bc9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW This review is timely and relevant because new experimental and theoretical findings suggest that cochlear mechanics from the nanoscale to the macroscale are affected by the mechanical properties of the tectorial membrane and the cochlea's spiral shape. RECENT FINDINGS Main tectorial membrane themes addressed in this review are composition and morphology, nanoscale mechanical interactions with the outer hair cell bundle, macroscale longitudinal coupling, fluid interaction with inner hair cell bundles, and macroscale dynamics and waves. Main cochlear spiral themes are macroscale, low-frequency energy focusing and microscale organ of Corti shear gain. SUMMARY Recent experimental and theoretical findings reveal exquisite sensitivity of cochlear mechanical performance to tectorial membrane structural organization, mechanics, and its positioning with respect to hair bundles. The cochlear spiral geometry is a major determinant of low-frequency hearing. These findings suggest a number of important research directions.
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Affiliation(s)
- Núria Gavara
- Auditory Mechanics Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, USA
| | - Daphne Manoussaki
- Department of Sciences, Technical University of Crete, Hania, Greece
| | - Richard S. Chadwick
- Auditory Mechanics Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, USA
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Current World Literature. Curr Opin Otolaryngol Head Neck Surg 2011; 19:410-3. [DOI: 10.1097/moo.0b013e32834b93e8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Liu CC, Gao SS, Yuan T, Steele C, Puria S, Oghalai JS. Biophysical mechanisms underlying outer hair cell loss associated with a shortened tectorial membrane. J Assoc Res Otolaryngol 2011; 12:577-94. [PMID: 21567249 PMCID: PMC3173552 DOI: 10.1007/s10162-011-0269-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2011] [Accepted: 04/17/2011] [Indexed: 01/09/2023] Open
Abstract
The tectorial membrane (TM) connects to the stereociliary bundles of outer hair cells (OHCs). Humans with an autosomal dominant C1509G mutation in alpha-tectorin, a protein constituent of the TM, are born with a partial hearing loss that worsens over time. The Tecta(C1509/+) transgenic mouse with the same point mutation has partial hearing loss secondary to a shortened TM that only contacts the first row of OHCs. As well, Tecta(C1509G/+) mice have increased expression of the OHC electromotility protein, prestin. We sought to determine whether these changes impact OHC survival. Distortion product otoacoustic emission thresholds in a quiet environment did not change to 6 months of age. However, noise exposure produced acute threshold shifts that fully recovered in Tecta (+/+) mice but only partially recovered in Tecta(C1509G/+) mice. While Tecta(+/+) mice lost OHCs primarily at the base and within all three rows, Tecta(C1509G/+) mice lost most of their OHCs in a more apical region of the cochlea and nearly completely within the first row. In order to estimate the impact of a shorter TM on the forces faced by the stereocilia within the first OHC row, both the wild type and the heterozygous conditions were simulated in a computational model. These analyses predicted that the shear force on the stereocilia is ~50% higher in the heterozygous condition. We then measured electrically induced movements of the reticular lamina in situ and found that while they decreased to the noise floor in prestin null mice, they were increased by 4.58 dB in Tecta(C1509G/+) mice compared to Tecta(+/+) mice. The increased movements were associated with a fourfold increase in OHC death as measured by vital dye staining. Together, these findings indicate that uncoupling the TM from some OHCs leads to partial hearing loss and places the remaining coupled OHCs at higher risk. Both the mechanics of the malformed TM and the increased prestin-related movements of the organ of Corti contribute to this higher risk profile.
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Affiliation(s)
- Christopher C. Liu
- The Bobby R. Alford Department of Otolaryngology–Head and Neck Surgery, Baylor College of Medicine, Houston, TX 77030 USA
| | - Simon S. Gao
- Department of Bioengineering, Rice University, Houston, TX 77005 USA
| | - Tao Yuan
- The Bobby R. Alford Department of Otolaryngology–Head and Neck Surgery, Baylor College of Medicine, Houston, TX 77030 USA
| | - Charles Steele
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94304-5739 USA
| | - Sunil Puria
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94304-5739 USA
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305-5739 USA
| | - John S. Oghalai
- Department of Bioengineering, Rice University, Houston, TX 77005 USA
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305-5739 USA
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