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Malesky C, Daniel D, Skoe E, Parham K. Serum Levels of Stereocilin as a Hearing Biomarker. Otolaryngol Head Neck Surg 2024. [PMID: 39033359 DOI: 10.1002/ohn.915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 07/04/2024] [Accepted: 07/10/2024] [Indexed: 07/23/2024]
Abstract
Noise-induced hearing loss (NIHL) often presents with an insidious onset, resulting from the cumulative effect of chronic, high-level noise exposure regardless of etiology. Stereocilin (STRC) is a protein that supports stereocilia attachment and cochlear hair cell function, 2 common targets of noise trauma. In this study, we explored the relationship between STRC and daily noise exposure in young, healthy adults. We found that higher noise exposure levels were associated with lower serum levels of STRC, as was the case for another inner-ear protein, prestin. There was a statistically significant positive correlation between serum STRC and prestin levels. These results support a biomarker approach for the diagnosis and monitoring of NIHL. The ability to detect and measure STRC in the blood also has implications for targeted gene therapy. STRC mutations are known to be associated with autosomal recessive deafness, a condition that is now amenable to targeted gene therapy.
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Affiliation(s)
- Carly Malesky
- University of Connecticut School of Medicine, Farmington, Connecticut, USA
| | - Diana Daniel
- Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Erika Skoe
- Department of Speech, Language, and Hearing Sciences, University of Connecticut, Storrs, Connecticut, USA
| | - Kourosh Parham
- Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, University of Connecticut Health, Farmington, Connecticut, USA
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Yeo XY, Kwon S, Rinai KR, Lee S, Jung S, Park R. A Consolidated Understanding of the Contribution of Redox Dysregulation in the Development of Hearing Impairment. Antioxidants (Basel) 2024; 13:598. [PMID: 38790703 PMCID: PMC11118506 DOI: 10.3390/antiox13050598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/26/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024] Open
Abstract
The etiology of hearing impairment is multifactorial, with contributions from both genetic and environmental factors. Although genetic studies have yielded valuable insights into the development and function of the auditory system, the contribution of gene products and their interaction with alternate environmental factors for the maintenance and development of auditory function requires further elaboration. In this review, we provide an overview of the current knowledge on the role of redox dysregulation as the converging factor between genetic and environmental factor-dependent development of hearing loss, with a focus on understanding the interaction of oxidative stress with the physical components of the peripheral auditory system in auditory disfunction. The potential involvement of molecular factors linked to auditory function in driving redox imbalance is an important promoter of the development of hearing loss over time.
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Affiliation(s)
- Xin Yi Yeo
- Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore;
- Department of Medical Science, College of Medicine, CHA University, Seongnam 13488, Republic of Korea;
| | - Soohyun Kwon
- Department of Medical Science, College of Medicine, CHA University, Seongnam 13488, Republic of Korea;
- Department of BioNanotechnology, Gachon University, Seongnam 13120, Republic of Korea
| | - Kimberley R. Rinai
- Department of Life Science, College of Medicine, CHA University, Seongnam 13488, Republic of Korea;
| | - Sungsu Lee
- Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Hospital and Medical School, Gwangju 61469, Republic of Korea;
| | - Sangyong Jung
- Department of Medical Science, College of Medicine, CHA University, Seongnam 13488, Republic of Korea;
| | - Raekil Park
- Department of Biomedical Science and Engineering, Gwangju Institute of Science & Technology (GIST), Gwangju 61005, Republic of Korea
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Melrose J. Keratan sulfate, an electrosensory neurosentient bioresponsive cell instructive glycosaminoglycan. Glycobiology 2024; 34:cwae014. [PMID: 38376199 PMCID: PMC10987296 DOI: 10.1093/glycob/cwae014] [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: 01/18/2024] [Revised: 02/12/2024] [Accepted: 02/13/2024] [Indexed: 02/21/2024] Open
Abstract
The roles of keratan sulfate (KS) as a proton detection glycosaminoglycan in neurosensory processes in the central and peripheral nervous systems is reviewed. The functional properties of the KS-proteoglycans aggrecan, phosphacan, podocalyxcin as components of perineuronal nets in neurosensory processes in neuronal plasticity, cognitive learning and memory are also discussed. KS-glycoconjugate neurosensory gels used in electrolocation in elasmobranch fish species and KS substituted mucin like conjugates in some tissue contexts in mammals need to be considered in sensory signalling. Parallels are drawn between KS's roles in elasmobranch fish neurosensory processes and its roles in mammalian electro mechanical transduction of acoustic liquid displacement signals in the cochlea by the tectorial membrane and stereocilia of sensory inner and outer hair cells into neural signals for sound interpretation. The sophisticated structural and functional proteins which maintain the unique high precision physical properties of stereocilia in the detection, transmittance and interpretation of acoustic signals in the hearing process are important. The maintenance of the material properties of stereocilia are essential in sound transmission processes. Specific, emerging roles for low sulfation KS in sensory bioregulation are contrasted with the properties of high charge density KS isoforms. Some speculations are made on how the molecular and electrical properties of KS may be of potential application in futuristic nanoelectronic, memristor technology in advanced ultrafast computing devices with low energy requirements in nanomachines, nanobots or molecular switches which could be potentially useful in artificial synapse development. Application of KS in such innovative areas in bioregulation are eagerly awaited.
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Affiliation(s)
- James Melrose
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW 2052, Australia
- Raymond Purves Laboratory, Institute of Bone and Joint Research, Kolling Institute of Medical Research, Northern Sydney Local Health District, Royal North Shore Hospital, St. Leonards, NSW 2065, Australia
- Sydney Medical School, Northern, University of Sydney at Royal North Shore Hospital, St. Leonards, NSW 2065, Australia
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Strelkova OS, Osgood RT, Tian CJ, Zhang X, Hale E, De-la-Torre P, Hathaway DM, Indzhykulian AA. PKHD1L1 is required for stereocilia bundle maintenance, durable hearing function and resilience to noise exposure. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.29.582786. [PMID: 38496629 PMCID: PMC10942330 DOI: 10.1101/2024.02.29.582786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Sensory hair cells of the cochlea are essential for hearing, relying on the mechanosensitive stereocilia bundle at their apical pole for their function. Polycystic Kidney and Hepatic Disease 1-Like 1 (PKHD1L1) is a stereocilia protein required for normal hearing in mice, and for the formation of the transient stereocilia surface coat, expressed during early postnatal development. While the function of the stereocilia coat remains unclear, growing evidence supports PKHD1L1 as a human deafness gene. In this study we carry out in depth characterization of PKHD1L1 expression in mice during development and adulthood, analyze hair-cell bundle morphology and hearing function in aging PKHD1L1-defficient mouse lines, and assess their susceptibility to noise damage. Our findings reveal that PKHD1L1-deficient mice display no disruption to bundle cohesion or tectorial membrane attachment-crown formation during development. However, starting from 6 weeks of age, PKHD1L1-defficient mice display missing stereocilia and disruptions to bundle coherence. Both conditional and constitutive PKHD1L1 knock-out mice develop high-frequency hearing loss progressing to lower frequencies with age. Furthermore, PKHD1L1-deficient mice are susceptible to permanent hearing loss following moderate acoustic overexposure, which induces only temporary hearing threshold shifts in wild-type mice. These results suggest a role for PKHD1L1 in establishing robust sensory hair bundles during development, necessary for maintaining bundle cohesion and function in response to acoustic trauma and aging.
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Affiliation(s)
| | | | | | - Xinyuan Zhang
- Department of Otolaryngology Head and Neck Surgery, Mass Eye and Ear, Harvard Medical School, Boston, MA, United States
| | - Evan Hale
- Department of Otolaryngology Head and Neck Surgery, Mass Eye and Ear, Harvard Medical School, Boston, MA, United States
| | - Pedro De-la-Torre
- Department of Otolaryngology Head and Neck Surgery, Mass Eye and Ear, Harvard Medical School, Boston, MA, United States
| | - Daniel M. Hathaway
- Department of Otolaryngology Head and Neck Surgery, Mass Eye and Ear, Harvard Medical School, Boston, MA, United States
| | - Artur A. Indzhykulian
- Department of Otolaryngology Head and Neck Surgery, Mass Eye and Ear, Harvard Medical School, Boston, MA, United States
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Miller KK, Wang P, Grillet N. SUB-Immunogold-SEM reveals nanoscale distribution of submembranous epitopes. RESEARCH SQUARE 2024:rs.3.rs-3876898. [PMID: 38343799 PMCID: PMC10854333 DOI: 10.21203/rs.3.rs-3876898/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
Electron microscopy paired with immunogold labeling is the most precise tool for protein localization. However, these methods are either cumbersome, resulting in small sample numbers and restricted quantification, or limited to identifying protein epitopes external to the membrane. Here, we introduce SUB-immunogold-SEM, a scanning electron microscopy technique that detects intracellular protein epitopes proximal to the membrane. We identified four critical sample preparation factors that contribute to the method's sensitivity and validate its efficacy through precise localization and high-powered quantification of cytoskeletal and transmembrane proteins. We evaluated the capabilities of SUB-immunogold-SEM on cells with highly differentiated apical surfaces: (i) auditory hair cells, revealing the presence of nanoscale Myosin rings at the tip of stereocilia; and (ii) respiratory multiciliate cells, mapping the distribution of the SARS-CoV-2 receptor ACE2 along the motile cilia. SUB-immunogold-SEM provides a novel solution for nanoscale protein localization at the exposed surface of any cell.
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Affiliation(s)
- Katharine K. Miller
- Department of Otolaryngology-Head & Neck Surgery, School of Medicine, 240 Pasteur Drive, Stanford University, Stanford, CA 94305, USA
| | - Pei Wang
- Department of Otolaryngology-Head & Neck Surgery, School of Medicine, 240 Pasteur Drive, Stanford University, Stanford, CA 94305, USA
| | - Nicolas Grillet
- Department of Otolaryngology-Head & Neck Surgery, School of Medicine, 240 Pasteur Drive, Stanford University, Stanford, CA 94305, USA
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Beurg M, Schwalbach ET, Fettiplace R. LHFPL5 is a key element in force transmission from the tip link to the hair cell mechanotransducer channel. Proc Natl Acad Sci U S A 2024; 121:e2318270121. [PMID: 38194445 PMCID: PMC10801851 DOI: 10.1073/pnas.2318270121] [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: 10/19/2023] [Accepted: 11/30/2023] [Indexed: 01/11/2024] Open
Abstract
During auditory transduction, sound-evoked vibrations of the hair cell stereociliary bundles open mechanotransducer (MET) ion channels via tip links extending from one stereocilium to its neighbor. How tension in the tip link is delivered to the channel is not fully understood. The MET channel comprises a pore-forming subunit, transmembrane channel-like protein (TMC1 or TMC2), aided by several accessory proteins, including LHFPL5 (lipoma HMGIC fusion partner-like 5). We investigated the role of LHFPL5 in transduction by comparing MET channel activation in outer hair cells of Lhfpl5-/- knockout mice with those in Lhfpl5+/- heterozygotes. The 10 to 90 percent working range of transduction in Tmc1+/+; Lhfpl5+/- was 52 nm, from which the single-channel gating force, Z, was evaluated as 0.34 pN. However, in Tmc1+/+; Lhfpl5-/- mice, the working range increased to 123 nm and Z more than halved to 0.13 pN, indicating reduced sensitivity. Tip link tension is thought to activate the channel via a gating spring, whose stiffness is inferred from the stiffness change on tip link destruction. The gating stiffness was ~40 percent of the total bundle stiffness in wild type but was virtually abolished in Lhfpl5-/-, implicating LHFPL5 as a principal component of the gating spring. The mutation Tmc1 p.D569N reduced the LHFPL5 immunolabeling in the stereocilia and like Lhfpl5-/- doubled the MET working range, but other deafness mutations had no effect on the dynamic range. We conclude that tip-link tension is transmitted to the channel primarily via LHFPL5; residual activation without LHFPL5 may occur by direct interaction between PCDH15 and TMC1.
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Affiliation(s)
- Maryline Beurg
- Department of Neuroscience, University of WisconsinSchool of Medicine and Public Health, Madison, WI53706
| | - Evan Travis Schwalbach
- Department of Neuroscience, University of WisconsinSchool of Medicine and Public Health, Madison, WI53706
| | - Robert Fettiplace
- Department of Neuroscience, University of WisconsinSchool of Medicine and Public Health, Madison, WI53706
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Wang P, Miller KK, He E, Dhawan SS, Cunningham CL, Grillet N. LOXHD1 is indispensable for coupling auditory mechanosensitive channels to the site of force transmission. RESEARCH SQUARE 2024:rs.3.rs-3752492. [PMID: 38260480 PMCID: PMC10802736 DOI: 10.21203/rs.3.rs-3752492/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Hearing is initiated in hair cells by the mechanical activation of ion channels in the hair bundle. The hair bundle is formed by stereocilia organized into rows of increasing heights interconnected by tip links, which convey sound-induced forces to stereocilia tips. The auditory mechanosensitive channels are complexes containing at least four protein-subunits - TMC1/2, TMIE, CIB2, and LHFPL51-16 - and are located at the tips of shorter stereocilia at a yet-undetermined distance from the lower tip link insertion point17. While multiple auditory channel subunits appear to interact with the tip link, it remains unknown whether their combined interaction alone can resist the high-frequency mechanical stimulations owing to sound. Here we show that an unanticipated additional element, LOXHD1, is indispensable for maintaining the TMC1 pore-forming channel subunits coupled to the tip link. We demonstrate that LOXHD1 is a unique element of the auditory mechanotransduction complex that selectively affects the localization of TMC1, but not its close developmental paralogue TMC2. Taking advantage of our novel immunogold scanning electron microscopy method for submembranous epitopes (SUB-immunogold-SEM), we demonstrate that TMC1 normally concentrates within 100-nm of the tip link insertion point. In LOXHD1's absence, TMC1 is instead mislocalized away from this force transmission site. Supporting this finding, we found that LOXHD1 interacts selectively in vitro with TMC1 but not with TMC2 while also binding to channel subunits CIB2 and LHFPL5 and tip-link protein PCDH15. SUB-immunogold-SEM additionally demonstrates that LOXHD1 and TMC1 are physically connected to the lower tip-link complex in situ. Our results show that the TMC1-driven mature channels require LOXHD1 to stay coupled to the tip link and remain functional, but the TMC2-driven developmental channels do not. As both tip links and TMC1 remain present in hair bundles lacking LOXHD1, it opens the possibility to reconnect them and restore hearing for this form of genetic deafness.
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Affiliation(s)
- Pei Wang
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 240 Pasteur Drive, Stanford, CA, USA
| | - Katharine K. Miller
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 240 Pasteur Drive, Stanford, CA, USA
| | - Enqi He
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 240 Pasteur Drive, Stanford, CA, USA
| | - Siddhant S. Dhawan
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 240 Pasteur Drive, Stanford, CA, USA
| | - Christopher L. Cunningham
- Pittsburgh Hearing Research Center, Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Nicolas Grillet
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 240 Pasteur Drive, Stanford, CA, USA
- Lead contact
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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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Abstract
PURPOSE OF REVIEW Hearing loss is the most common sensory deficit and in young children sensorineural hearing loss is most frequently genetic in etiology. Hearing aids and cochlear implant do not restore normal hearing. There is significant research and commercial interest in directly addressing the root cause of hearing loss through gene therapies. This article provides an overview of major barriers to cochlear gene therapy and recent advances in preclinical development of precision treatments of genetic deafness. RECENT FINDINGS Several investigators have recently described successful gene therapies in many common forms of genetic hearing loss in animal models. Elegant strategies that do not target a specific pathogenic variant, such as mini gene replacement and mutation-agnostic RNA interference (RNAi) with engineered replacement, facilitate translation of these findings to development of human therapeutics. Clinical trials for human gene therapies are in active recruitment. SUMMARY Gene therapies for hearing loss are expected to enter clinical trials in the immediate future. To provide referral for appropriate trials and counseling regarding benefits of genetic hearing loss evaluation, specialists serving children with hearing loss such as pediatricians, geneticists, genetic counselors, and otolaryngologists should be acquainted with ongoing developments in precision therapies.
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Affiliation(s)
- Miles J. Klimara
- Molecular Otolaryngology & Renal Research Laboratories, Department of Otolaryngology – Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
| | - Richard J.H. Smith
- Molecular Otolaryngology & Renal Research Laboratories, Department of Otolaryngology – Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, USA
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Benoit C, Carlson RJ, King MC, Horn DL, Rubinstein JT. Behavioral characterization of the cochlear amplifier lesion due to loss of function of stereocilin (STRC) in human subjects. Hear Res 2023; 439:108898. [PMID: 37890241 PMCID: PMC10756798 DOI: 10.1016/j.heares.2023.108898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 09/12/2023] [Accepted: 10/19/2023] [Indexed: 10/29/2023]
Abstract
Loss of function of stereocilin (STRC) is the second most common cause of inherited hearing loss. The loss of the stereocilin protein, encoded by the STRC gene, induces the loss of connection between outer hair cells and tectorial membrane. This only affects the outer hair cells (OHCs) function, involving deficits of active cochlear frequency selectivity and amplifier functions despite preservation of normal inner hair cells. Better understanding of cochlear features associated with mutation of STRC will improve our knowledge of normal cochlear function, the pathophysiology of hearing impairment, and potentially enhance hearing aid and cochlear implant signal processing. Nine subjects with homozygous or compound heterozygous loss of function mutations in STRC were included, age 7-24 years. Temporal and spectral modulation perception were measured, characterized by spectral and temporal modulation transfer functions. Speech-in-noise perception was studied with spondee identification in adaptive steady-state noise and AzBio sentences with 0 and -5 dB SNR multitalker babble. Results were compared with normal hearing (NH) and cochlear implant (CI) listeners to place STRC-/- listeners' hearing capacity in context. Spectral ripple discrimination thresholds in the STRC-/- subjects were poorer than in NH listeners (p < 0.0001) but remained better than for CI listeners (p < 0.0001). Frequency resolution appeared impaired in the STRC-/- group compared to NH listeners but did not reach statistical significance (p = 0.06). Compared to NH listeners, amplitude modulation detection thresholds in the STRC-/- group did not reach significance (p= 0.06) but were better than in CI subjects (p < 0.0001). Temporal resolution in STRC-/- subjects was similar to NH (p = 0.98) but better than in CI listeners (p = 0.04). The spondee reception threshold in the STRC-/- group was worse than NH listeners (p = 0.0008) but better than CI listeners (p = 0.0001). For AzBio sentences, performance at 0 dB SNR was similar between the STRC-/- group and the NH group, 88 % and 97 % respectively. For -5 dB SNR, the STRC-/- performance was significantly poorer than NH, 40 % and 85 % respectively, yet much better than with CI who performed at 54 % at +5 dB SNR in children and 53 % at + 10 dB SNR in adults. To our knowledge, this is the first study of the psychoacoustic performance of human subjects lacking cochlear amplification but with normal inner hair cell function. Our data demonstrate preservation of temporal resolution and a trend to impaired frequency resolution in this group without reaching statistical significance. Speech-in-noise perception compared to NH listeners was impaired as well. All measures were better than those in CI listeners. It remains to be seen if hearing aid modifications, customized for the spectral deficits in STRC-/- listeners can improve speech understanding in noise. Since cochlear implants are also limited by deficient spectral selectivity, STRC-/- hearing may provide an upper bound on what could be obtained with better temporal coding in electrical stimulation.
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Affiliation(s)
- Charlotte Benoit
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, WA, USA.
| | - Ryan J Carlson
- Departments of Genome Sciences and Medicine, University of Washington, Seattle, WA, USA
| | - Mary-Claire King
- Departments of Genome Sciences and Medicine, University of Washington, Seattle, WA, USA
| | - David L Horn
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, WA, USA; Department of Speech and Hearing Sciences, University of Washington, Seattle, WA, USA; Division of Pediatric Otolaryngology, Department of Surgery, Seattle Children's Hospital, Seattle, WA, USA
| | - Jay T Rubinstein
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, WA, USA; Department of Bioengineering, University of Washington, Seattle, WA, USA
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Domínguez-Ruiz M, Ruiz-Palmero L, Buonfiglio PI, García-Vaquero I, Gómez-Rosas E, Goñi M, Villamar M, Morín M, Moreno-Pelayo MA, Elgoyhen AB, del Castillo FJ, Dalamón V, del Castillo I. Novel Pathogenic Variants in the Gene Encoding Stereocilin ( STRC) Causing Non-Syndromic Moderate Hearing Loss in Spanish and Argentinean Subjects. Biomedicines 2023; 11:2943. [PMID: 38001944 PMCID: PMC10668944 DOI: 10.3390/biomedicines11112943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 10/24/2023] [Accepted: 10/27/2023] [Indexed: 11/26/2023] Open
Abstract
Non-syndromic hearing impairment (NSHI) is a very heterogeneous genetic condition, involving over 130 genes. Mutations in GJB2, encoding connexin-26, are a major cause of NSHI (the DFNB1 type), but few other genes have significant epidemiological contributions. Mutations in the STRC gene result in the DFNB16 type of autosomal recessive NSHI, a common cause of moderate hearing loss. STRC is located in a tandem duplicated region that includes the STRCP1 pseudogene, and so it is prone to rearrangements causing structural variations. Firstly, we screened a cohort of 122 Spanish familial cases of non-DFNB1 NSHI with at least two affected siblings and unaffected parents, and with different degrees of hearing loss (mild to profound). Secondly, we screened a cohort of 64 Spanish sporadic non-DFNB1 cases, and a cohort of 35 Argentinean non-DFNB1 cases, all of them with moderate hearing loss. Amplification of marker D15S784, massively parallel DNA sequencing, multiplex ligation-dependent probe amplification and long-range gene-specific PCR followed by Sanger sequencing were used to search and confirm single-nucleotide variants (SNVs) and deletions involving STRC. Causative variants were found in 13 Spanish familial cases (10.7%), 5 Spanish simplex cases (7.8%) and 2 Argentinean cases (5.7%). In all, 34 deleted alleles and 6 SNVs, 5 of which are novel. All affected subjects had moderate hearing impairment. Our results further support this strong genotype-phenotype correlation and highlight the significant contribution of STRC mutations to moderate NSHI in the Spanish population.
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Affiliation(s)
- María Domínguez-Ruiz
- Servicio de Genética, Hospital Universitario Ramón y Cajal, 28034 Madrid, Spain; (M.D.-R.); (L.R.-P.); (I.G.-V.); (E.G.-R.); (M.G.); (M.V.); (M.M.); (M.A.M.-P.); (F.J.d.C.)
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 28034 Madrid, Spain
| | - Laura Ruiz-Palmero
- Servicio de Genética, Hospital Universitario Ramón y Cajal, 28034 Madrid, Spain; (M.D.-R.); (L.R.-P.); (I.G.-V.); (E.G.-R.); (M.G.); (M.V.); (M.M.); (M.A.M.-P.); (F.J.d.C.)
| | - Paula I. Buonfiglio
- Laboratory of Physiology and Genetics of Hearing, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres”, Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, Ciudad Autónoma de Buenos Aires C1428ADN, Argentina; (P.I.B.); (A.B.E.)
| | - Irene García-Vaquero
- Servicio de Genética, Hospital Universitario Ramón y Cajal, 28034 Madrid, Spain; (M.D.-R.); (L.R.-P.); (I.G.-V.); (E.G.-R.); (M.G.); (M.V.); (M.M.); (M.A.M.-P.); (F.J.d.C.)
| | - Elena Gómez-Rosas
- Servicio de Genética, Hospital Universitario Ramón y Cajal, 28034 Madrid, Spain; (M.D.-R.); (L.R.-P.); (I.G.-V.); (E.G.-R.); (M.G.); (M.V.); (M.M.); (M.A.M.-P.); (F.J.d.C.)
| | - Marina Goñi
- Servicio de Genética, Hospital Universitario Ramón y Cajal, 28034 Madrid, Spain; (M.D.-R.); (L.R.-P.); (I.G.-V.); (E.G.-R.); (M.G.); (M.V.); (M.M.); (M.A.M.-P.); (F.J.d.C.)
| | - Manuela Villamar
- Servicio de Genética, Hospital Universitario Ramón y Cajal, 28034 Madrid, Spain; (M.D.-R.); (L.R.-P.); (I.G.-V.); (E.G.-R.); (M.G.); (M.V.); (M.M.); (M.A.M.-P.); (F.J.d.C.)
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 28034 Madrid, Spain
| | - Matías Morín
- Servicio de Genética, Hospital Universitario Ramón y Cajal, 28034 Madrid, Spain; (M.D.-R.); (L.R.-P.); (I.G.-V.); (E.G.-R.); (M.G.); (M.V.); (M.M.); (M.A.M.-P.); (F.J.d.C.)
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 28034 Madrid, Spain
| | - Miguel A. Moreno-Pelayo
- Servicio de Genética, Hospital Universitario Ramón y Cajal, 28034 Madrid, Spain; (M.D.-R.); (L.R.-P.); (I.G.-V.); (E.G.-R.); (M.G.); (M.V.); (M.M.); (M.A.M.-P.); (F.J.d.C.)
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 28034 Madrid, Spain
| | - Ana B. Elgoyhen
- Laboratory of Physiology and Genetics of Hearing, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres”, Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, Ciudad Autónoma de Buenos Aires C1428ADN, Argentina; (P.I.B.); (A.B.E.)
- Instituto de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires C1121ABG, Argentina
| | - Francisco J. del Castillo
- Servicio de Genética, Hospital Universitario Ramón y Cajal, 28034 Madrid, Spain; (M.D.-R.); (L.R.-P.); (I.G.-V.); (E.G.-R.); (M.G.); (M.V.); (M.M.); (M.A.M.-P.); (F.J.d.C.)
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 28034 Madrid, Spain
| | - Viviana Dalamón
- Laboratory of Physiology and Genetics of Hearing, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres”, Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, Ciudad Autónoma de Buenos Aires C1428ADN, Argentina; (P.I.B.); (A.B.E.)
| | - Ignacio del Castillo
- Servicio de Genética, Hospital Universitario Ramón y Cajal, 28034 Madrid, Spain; (M.D.-R.); (L.R.-P.); (I.G.-V.); (E.G.-R.); (M.G.); (M.V.); (M.M.); (M.A.M.-P.); (F.J.d.C.)
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 28034 Madrid, Spain
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12
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Cortada M, Levano S, Hall MN, Bodmer D. mTORC2 regulates auditory hair cell structure and function. iScience 2023; 26:107687. [PMID: 37694145 PMCID: PMC10484995 DOI: 10.1016/j.isci.2023.107687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 07/14/2023] [Accepted: 08/17/2023] [Indexed: 09/12/2023] Open
Abstract
mTOR broadly controls cell growth, but little is known about the role of mTOR complex 2 (mTORC2) in the inner ear. To investigate the role of mTORC2 in sensory hair cells (HCs), we generated HC-specific Rictor knockout (HC-RicKO) mice. HC-RicKO mice exhibited early-onset, progressive, and profound hearing loss. Increased DPOAE thresholds indicated outer HC dysfunction. HCs are lost, but this occurs after hearing loss. Ultrastructural analysis revealed stunted and absent stereocilia in outer HCs. In inner HCs, the number of synapses was significantly decreased and the remaining synapses displayed a disrupted actin cytoskeleton and disorganized Ca2+ channels. Thus, the mTORC2 signaling pathway plays an important role in regulating auditory HC structure and function via regulation of the actin cytoskeleton. These results provide molecular insights on a central regulator of cochlear HCs and thus hearing.
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Affiliation(s)
- Maurizio Cortada
- Department of Biomedicine, University of Basel, CH-4031 Basel, Switzerland
| | - Soledad Levano
- Department of Biomedicine, University of Basel, CH-4031 Basel, Switzerland
| | | | - Daniel Bodmer
- Department of Biomedicine, University of Basel, CH-4031 Basel, Switzerland
- Clinic for Otorhinolaryngology, Head and Neck Surgery, University of Basel Hospital, CH-4031 Basel, Switzerland
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13
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Makrogkikas S, Cheng RK, Lu H, Roy S. A conserved function of Pkhd1l1, a mammalian hair cell stereociliary coat protein, in regulating hearing in zebrafish. J Neurogenet 2023; 37:85-92. [PMID: 36960824 DOI: 10.1080/01677063.2023.2187792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 03/02/2023] [Indexed: 03/25/2023]
Abstract
Pkhd1l1 is predicted to encode a very large type-I transmembrane protein, but its function has largely remained obscure. Recently, it was shown that Pkhdl1l1 is a component of the coat that decorates stereocilia of outer hair cells in the mouse ear. Consistent with this localization, conditional deletion of Pkhd1l1 specifically from hair cells, was associated with progressive hearing loss. In the zebrafish, there are two paralogous pkhd1l1 genes - pkhd1l1α and pkhd1l1β. Using CRISPR-Cas9 mediated gene editing, we generated loss-of-function alleles for both and show that the double mutants exhibit nonsense-mediated-decay (NMD) of the RNAs. With behavioural assays, we demonstrate that zebrafish pkhd1l1 genes also regulate hearing; however, in contrast to Pkhd1l1 mutant mice, which develop progressive hearing loss, the double mutant zebrafish exhibited statistically significant hearing loss even from the larval stage. Our data highlight a conserved function of Pkhd1l1 in hearing and based on these findings from animal models, we postulate that PKHD1L1 could be a candidate gene for sensorineural hearing loss (SNHL) in humans.
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Affiliation(s)
- Stylianos Makrogkikas
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Ruey-Kuang Cheng
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Hao Lu
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Sudipto Roy
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
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14
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McCaffrey TA, Toma I, Yang Z, Katz R, Reiner J, Mazhari R, Shah P, Falk Z, Wargowsky R, Goldman J, Jones D, Shtokalo D, Antonets D, Jepson T, Fetisova A, Jaatinen K, Ree N, Ri M. RNAseq profiling of blood from patients with coronary artery disease: Signature of a T cell imbalance. JOURNAL OF MOLECULAR AND CELLULAR CARDIOLOGY PLUS 2023; 4:100033. [PMID: 37303712 PMCID: PMC10256136 DOI: 10.1016/j.jmccpl.2023.100033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Background Cardiovascular disease had a global prevalence of 523 million cases and 18.6 million deaths in 2019. The current standard for diagnosing coronary artery disease (CAD) is coronary angiography either by invasive catheterization (ICA) or computed tomography (CTA). Prior studies employed single-molecule, amplification-independent RNA sequencing of whole blood to identify an RNA signature in patients with angiographically confirmed CAD. The present studies employed Illumina RNAseq and network co-expression analysis to identify systematic changes underlying CAD. Methods Whole blood RNA was depleted of ribosomal RNA (rRNA) and analyzed by Illumina total RNA sequencing (RNAseq) to identify transcripts associated with CAD in 177 patients presenting for elective invasive coronary catheterization. The resulting transcript counts were compared between groups to identify differentially expressed genes (DEGs) and to identify patterns of changes through whole genome co-expression network analysis (WGCNA). Results The correlation between Illumina amplified RNAseq and the prior SeqLL unamplified RNAseq was quite strong (r = 0.87), but there was only 9 % overlap in the DEGs identified. Consistent with the prior RNAseq, the majority (93 %) of DEGs were down-regulated ~1.7-fold in patients with moderate to severe CAD (>20 % stenosis). DEGs were predominantly related to T cells, consistent with known reductions in Tregs in CAD. Network analysis did not identify pre-existing modules with a strong association with CAD, but patterns of T cell dysregulation were evident. DEGs were enriched for transcripts associated with ciliary and synaptic transcripts, consistent with changes in the immune synapse of developing T cells. Conclusions These studies confirm and extend a novel mRNA signature of a Treg-like defect in CAD. The pattern of changes is consistent with stress-related changes in the maturation of T and Treg cells, possibly due to changes in the immune synapse.
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Affiliation(s)
- Timothy A. McCaffrey
- Department of Medicine, Division of Genomic Medicine, The George Washington University, 2300 I Street NW, Washington, DC 20037, United States of America
- The St. Laurent Institute, 317 New Boston Street, Woburn, MA 01801, United States of America
- Department of Microbiology, Immunology, and Tropical Medicine, The George Washington University, 2300 I Street NW, Washington, DC 20037, United States of America
- True Bearing Diagnostics, 2450 Virginia Avenue, Washington, DC 20037, United States of America
| | - Ian Toma
- Department of Medicine, Division of Genomic Medicine, The George Washington University, 2300 I Street NW, Washington, DC 20037, United States of America
- Department of Clinical Research and Leadership, The George Washington University, 2300 I Street NW, Washington, DC 20037, United States of America
- True Bearing Diagnostics, 2450 Virginia Avenue, Washington, DC 20037, United States of America
| | - Zhaoqing Yang
- Department of Medicine, Division of Genomic Medicine, The George Washington University, 2300 I Street NW, Washington, DC 20037, United States of America
| | - Richard Katz
- Department of Medicine, Division of Cardiology, The George Washington University, 2300 I Street NW, Washington, DC 20037, United States of America
| | - Jonathan Reiner
- Department of Medicine, Division of Cardiology, The George Washington University, 2300 I Street NW, Washington, DC 20037, United States of America
| | - Ramesh Mazhari
- Department of Medicine, Division of Cardiology, The George Washington University, 2300 I Street NW, Washington, DC 20037, United States of America
| | - Palak Shah
- INOVA Heart and Vascular Institute, 3300 Gallows Road, Fairfax, VA 22042, United States of America
| | - Zachary Falk
- Department of Medicine, Division of Genomic Medicine, The George Washington University, 2300 I Street NW, Washington, DC 20037, United States of America
| | - Richard Wargowsky
- Department of Medicine, Division of Genomic Medicine, The George Washington University, 2300 I Street NW, Washington, DC 20037, United States of America
| | - Jennifer Goldman
- Department of Medicine, Division of Genomic Medicine, The George Washington University, 2300 I Street NW, Washington, DC 20037, United States of America
| | - Dan Jones
- SeqLL, Inc., 3 Federal Street, Billerica, MA 01821, United States of America
| | - Dmitry Shtokalo
- The St. Laurent Institute, 317 New Boston Street, Woburn, MA 01801, United States of America
- A.P. Ershov Institute of Informatics Systems SB RAS, 6, Acad. Lavrentyeva Ave, Novosibirsk 630090, Russia
| | - Denis Antonets
- The St. Laurent Institute, 317 New Boston Street, Woburn, MA 01801, United States of America
| | - Tisha Jepson
- Department of Medicine, Division of Genomic Medicine, The George Washington University, 2300 I Street NW, Washington, DC 20037, United States of America
- The St. Laurent Institute, 317 New Boston Street, Woburn, MA 01801, United States of America
- True Bearing Diagnostics, 2450 Virginia Avenue, Washington, DC 20037, United States of America
| | - Anastasia Fetisova
- Department of Medicine, Division of Genomic Medicine, The George Washington University, 2300 I Street NW, Washington, DC 20037, United States of America
| | - Kevin Jaatinen
- Department of Medicine, Division of Genomic Medicine, The George Washington University, 2300 I Street NW, Washington, DC 20037, United States of America
| | - Natalia Ree
- Center for Mitochondrial Functional Genomics, Institute of Living Systems, Immanuel Kant Baltic Federal University, Kalingrad 236040, Russia
| | - Maxim Ri
- The St. Laurent Institute, 317 New Boston Street, Woburn, MA 01801, United States of America
- A.P. Ershov Institute of Informatics Systems SB RAS, 6, Acad. Lavrentyeva Ave, Novosibirsk 630090, Russia
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15
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Achard S, Campion M, Parodi M, MacAskill M, Hochet B, Simon F, Rouillon I, Jonard L, Serey-Gaut M, Denoyelle F, Loundon N, Marlin S. Recurrent Benign Paroxysmal Positional Vertigo in DFNB16 Patients with Biallelic STRC Gene Deletions. Otol Neurotol 2023; 44:e241-e245. [PMID: 36764706 DOI: 10.1097/mao.0000000000003825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
OBJECTIVE Deletions of STRC gene (DFNB16) account for 12% of isolated congenital mild to moderate hearing loss (HL). In mice, the stereocilin protein, encoded by STRC , is present in the vestibular kinocilium embedded in the otoconial membrane of the utricular macula. Despite this, effects on vestibular function have not been widely investigated. The aim of this study was to investigate the prevalence of benign paroxysmal positional vertigo (BPPV) in a cohort of DFNB16 patients. STUDY DESIGN Observational descriptive epidemiological study. SETTING Single-center study, in a tertiary referral center. PATIENTS Older than 5 years, with a genetic diagnosis of HL related to biallelic STRC gene deletions, diagnosed between 2015 and 2021. INTERVENTION Patients or their parents were interviewed to determine whether they had experienced vertigo or episodes of BPPV. MAIN OUTCOME MEASURE Criteria were at least five acute episodes of rotatory vertigo, each lasting less than 1 minute, episodes triggered by changes in specific head position, and an absence of neurological symptoms. RESULTS Sixty-four patients having mild (33%) to moderate (66%) HL were included. Median age was 15 years (range, 6-48 yr). Prevalence of BPPV was 39% (25 of 64). Median age of first onset was 13 years (range, 3-18 yr). CONCLUSIONS This study showed recurrent BPPV and early age of onset in patients with biallelic STRC gene deletions. BPPV may be associated with the HL phenotype in patients with STRC gene deletions. It is important to inform patients and families of this potential risk such that appropriate management can be proposed.
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Affiliation(s)
| | - Margaux Campion
- Department of Paediatric Otolaryngology, 149 rue de Sèvres, Hôpital Necker-Enfants Malades, AP-HP
| | | | - Melissa MacAskill
- Centre de Recherche en Audiologie pédiatrique, 149 rue de Sèvres, Hôpital Necker, F-75015 Paris
| | - Baptiste Hochet
- Department of Otolaryngology, 40 Rue Worth, 92150 Suresnes, Hôpital Foch, Suresnes F-92150
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16
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Sharkova M, Chow E, Erickson T, Hocking JC. The morphological and functional diversity of apical microvilli. J Anat 2023; 242:327-353. [PMID: 36281951 PMCID: PMC9919547 DOI: 10.1111/joa.13781] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 10/03/2022] [Accepted: 10/05/2022] [Indexed: 11/30/2022] Open
Abstract
Sensory neurons use specialized apical processes to perceive external stimuli and monitor internal body conditions. The apical apparatus can include cilia, microvilli, or both, and is adapted for the functions of the particular cell type. Photoreceptors detect light through a large, modified cilium (outer segment), that is supported by a surrounding ring of microvilli-like calyceal processes (CPs). Although first reported 150 years ago, CPs remain poorly understood. As a basis for future study, we therefore conducted a review of existing literature about sensory cell microvilli, which can act either as the primary sensory detector or as support for a cilia-based detector. While all microvilli are finger-like cellular protrusions with an actin core, the processes vary across cell types in size, number, arrangement, dynamics, and function. We summarize the current state of knowledge about CPs and the characteristics of the microvilli found on inner ear hair cells (stereocilia) and cerebral spinal fluid-contacting neurons, with comparisons to the brush border of the intestinal and renal epithelia. The structure, stability, and dynamics of the actin core are regulated by a complement of actin-binding proteins, which includes both common components and unique features when compared across cell types. Further, microvilli are often supported by lateral links, a glycocalyx, and a defined extracellular matrix, each adapted to the function and environment of the cell. Our comparison of microvillar features will inform further research into how CPs support photoreceptor function, and also provide a general basis for investigations into the structure and functions of apical microvilli found on sensory neurons.
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Affiliation(s)
- Maria Sharkova
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Erica Chow
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Timothy Erickson
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Jennifer C Hocking
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Division of Anatomy, Department of Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
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17
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Lindner LA, Derstroff D, Oliver D, Reimann K. Distribution of ciliary adaptor proteins tubby and TULP3 in the organ of Corti. Front Neurosci 2023; 17:1162937. [PMID: 37144094 PMCID: PMC10151737 DOI: 10.3389/fnins.2023.1162937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 03/28/2023] [Indexed: 05/06/2023] Open
Abstract
Tubby-like proteins are membrane-associated adaptors that mediate directional trafficking into primary cilia. In inner ear sensory epithelia, cilia-including the hair cell's kinocilium-play important roles as organizers of polarity, tissue architecture and cellular function. However, auditory dysfunction in tubby mutant mice was recently found to be related to a non-ciliary function of tubby, the organization of a protein complex in sensory hair bundles of auditory outer hair cells (OHCs). Targeting of signaling components into cilia in the cochlea might therefore rather rely on closely related tubby-like proteins (TULPs). In this study, we compared cellular and subcellular localization of tubby and TULP3 in the mouse inner ear sensory organs. Immunofluorescence microscopy confirmed the previously reported highly selective localization of tubby in the stereocilia tips of OHCs and revealed a previously unnoticed transient localization to kinocilia during early postnatal development. TULP3 was detected in the organ of Corti and vestibular sensory epithelium, where it displayed a complex spatiotemporal pattern. TULP3 localized to kinocilia of cochlear and vestibular hair cells in early postnatal development but disappeared subsequently before the onset of hearing. This pattern suggested a role in targeting ciliary components into kinocilia, possibly related to the developmental processes that shape the sensory epithelia. Concurrent with loss from kinocilia, pronounced TULP3 immunolabeling progressively appeared at microtubule bundles in non-sensory Pillar (PCs) and Deiters cells (DC). This subcellular localization may indicate a novel function of TULP proteins associated with the formation or regulation of microtubule-based cellular structures.
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Affiliation(s)
- Laura A. Lindner
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Marburg, Philipps-University Marburg, Marburg, Germany
| | - Dennis Derstroff
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Marburg, Philipps-University Marburg, Marburg, Germany
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, Marburg, Germany
| | - Katrin Reimann
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Marburg, Philipps-University Marburg, Marburg, Germany
- *Correspondence: Katrin Reimann,
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18
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Achard S, Simon F, Denoyelle F, Marlin S. Recurrent benign paroxysmal positional vertigo in two DFNB16 siblings: A CARE case report. Eur Ann Otorhinolaryngol Head Neck Dis 2022; 140:127-129. [DOI: 10.1016/j.anorl.2022.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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19
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Qiu X, Müller U. Sensing sound: Cellular specializations and molecular force sensors. Neuron 2022; 110:3667-3687. [PMID: 36223766 PMCID: PMC9671866 DOI: 10.1016/j.neuron.2022.09.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 08/03/2022] [Accepted: 09/14/2022] [Indexed: 11/08/2022]
Abstract
Organisms of all phyla express mechanosensitive ion channels with a wide range of physiological functions. In recent years, several classes of mechanically gated ion channels have been identified. Some of these ion channels are intrinsically mechanosensitive. Others depend on accessory proteins to regulate their response to mechanical force. The mechanotransduction machinery of cochlear hair cells provides a particularly striking example of a complex force-sensing machine. This molecular ensemble is embedded into a specialized cellular compartment that is crucial for its function. Notably, mechanotransduction channels of cochlear hair cells are not only critical for auditory perception. They also shape their cellular environment and regulate the development of auditory circuitry. Here, we summarize recent discoveries that have shed light on the composition of the mechanotransduction machinery of cochlear hair cells and how this machinery contributes to the development and function of the auditory system.
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Affiliation(s)
- Xufeng Qiu
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ulrich Müller
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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20
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Abdala C, Luo P, Shera CA. Characterizing the Relationship Between Reflection and Distortion Otoacoustic Emissions in Normal-Hearing Adults. J Assoc Res Otolaryngol 2022; 23:647-664. [PMID: 35804277 PMCID: PMC9613820 DOI: 10.1007/s10162-022-00857-z] [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: 02/04/2022] [Accepted: 06/24/2022] [Indexed: 11/28/2022] Open
Abstract
Otoacoustic emissions (OAEs) arise from one (or a combination) of two basic generation mechanisms in the cochlea: nonlinear distortion and linear reflection. As a result of having distinct generation processes, these two classes of emissions may provide non-redundant information about hair-cell integrity and show distinct sensitivities to cochlear pathology. Here, we characterize the relationship between reflection and distortion emissions in normal hearers across a broad frequency and stimulus-level space using novel analysis techniques. Furthermore, we illustrate the promise of this approach in a small group of individuals with mild-moderate hearing loss. A "joint-OAE profile" was created by measuring interleaved swept-tone stimulus-frequency OAEs (SFOAEs) and 2f1-f2 distortion-product OAEs (DPOAEs) in the same ears using well-considered parameters. OAE spectra and input/output functions were calculated across five octaves. Using our specific recording protocol and analysis scheme, SFOAEs in normal hearers had higher levels than did DPOAEs, with the most pronounced differences occurring at the highest stimulus levels. Also, SFOAE compression occurred at higher stimulus levels (than did DPOAE compression) and its growth in the compressed region was steeper. The diagnostic implications of these findings and the influence of the measurement protocol on both OAEs (and on their relationship) are discussed.
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Affiliation(s)
- Carolina Abdala
- Auditory Research Center, Caruso Department of Otolaryngology, University of Southern California, Los Angeles, CA, 90033, USA.
| | - Ping Luo
- Auditory Research Center, Caruso Department of Otolaryngology, University of Southern California, Los Angeles, CA, 90033, USA
| | - Christopher A Shera
- Auditory Research Center, Caruso Department of Otolaryngology, University of Southern California, Los Angeles, CA, 90033, USA
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA, 90089, USA
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21
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Signatures of cochlear processing in neuronal coding of auditory information. Mol Cell Neurosci 2022; 120:103732. [PMID: 35489636 DOI: 10.1016/j.mcn.2022.103732] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 04/19/2022] [Accepted: 04/21/2022] [Indexed: 11/22/2022] Open
Abstract
The vertebrate ear is endowed with remarkable perceptual capabilities. The faintest sounds produce vibrations of magnitudes comparable to those generated by thermal noise and can nonetheless be detected through efficient amplification of small acoustic stimuli. Two mechanisms have been proposed to underlie such sound amplification in the mammalian cochlea: somatic electromotility and active hair-bundle motility. These biomechanical mechanisms may work in concert to tune auditory sensitivity. In addition to amplitude sensitivity, the hearing system shows exceptional frequency discrimination allowing mammals to distinguish complex sounds with great accuracy. For instance, although the wide hearing range of humans encompasses frequencies from 20 Hz to 20 kHz, our frequency resolution extends to one-thirtieth of the interval between successive keys on a piano. In this article, we review the different cochlear mechanisms underlying sound encoding in the auditory system, with a particular focus on the frequency decomposition of sounds. The relation between peak frequency of activation and location along the cochlea - known as tonotopy - arises from multiple gradients in biophysical properties of the sensory epithelium. Tonotopic mapping represents a major organizational principle both in the peripheral hearing system and in higher processing levels and permits the spectral decomposition of complex tones. The ribbon synapses connecting sensory hair cells to auditory afferents and the downstream spiral ganglion neurons are also tuned to process periodic stimuli according to their preferred frequency. Though sensory hair cells and neurons necessarily filter signals beyond a few kHz, many animals can hear well beyond this range. We finally describe how the cochlear structure shapes the neural code for further processing in order to send meaningful information to the brain. Both the phase-locked response of auditory nerve fibers and tonotopy are key to decode sound frequency information and place specific constraints on the downstream neuronal network.
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22
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Shubina-Oleinik O, Nist-Lund C, French C, Rockowitz S, Shearer AE, Holt JR. Dual-vector gene therapy restores cochlear amplification and auditory sensitivity in a mouse model of DFNB16 hearing loss. SCIENCE ADVANCES 2021; 7:eabi7629. [PMID: 34910522 PMCID: PMC8673757 DOI: 10.1126/sciadv.abi7629] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 10/28/2021] [Indexed: 05/27/2023]
Abstract
Hearing loss affects an estimated 466 million people worldwide, with a substantial fraction due to genetic causes. Approximately 16% of genetic hearing loss is caused by pathogenic mutations in STRC, a gene that encodes the protein stereocilin. To develop gene therapy strategies for patients with STRC hearing loss, we generated a mouse model with a targeted deletion in the Strc gene. We devised a novel dual-vector approach to circumvent the size limitation of AAV vectors and drive expression of full-length STRC protein. To target outer hair cells, which are difficult to transduce, we used synthetic AAV9-PHP.B vectors for efficient dual-vector transduction. We report robust recovery of exogenous STRC expression in outer hair cells of Strc-deficient mice, recovery of hair bundle morphology, substantially improved cochlear amplification, and enhanced auditory sensitivity. The data raise the prospect that our strategy could benefit ~2.3 million patients worldwide affected by STRC mutations.
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Affiliation(s)
- Olga Shubina-Oleinik
- Department of Otolaryngology, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Carl Nist-Lund
- Department of Otolaryngology, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Courtney French
- Children’s Rare Disease Cohort Initiative, Boston Children’s Hospital, Boston, MA 02115, USA
| | - Shira Rockowitz
- Children’s Rare Disease Cohort Initiative, Boston Children’s Hospital, Boston, MA 02115, USA
| | - A. Eliot Shearer
- Department of Otolaryngology, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115, USA
- Children’s Rare Disease Cohort Initiative, Boston Children’s Hospital, Boston, MA 02115, USA
| | - Jeffrey R. Holt
- Department of Otolaryngology, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115, USA
- Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Boston, MA 02115, USA
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Evaluation of copy number variants for genetic hearing loss: a review of current approaches and recent findings. Hum Genet 2021; 141:387-400. [PMID: 34811589 DOI: 10.1007/s00439-021-02365-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 09/02/2021] [Indexed: 01/22/2023]
Abstract
Structural variation includes a change in copy number, orientation, or location of a part of the genome. Copy number variants (CNVs) are a common cause of genetic hearing loss, comprising nearly 20% of diagnosed cases. While large deletions involving the gene STRC are the most common pathogenic CNVs, a significant proportion of known hearing loss genes also contain pathogenic CNVs. In this review, we provide an overview of currently used methods for detection of CNVs in genes known to cause hearing loss including molecular techniques such as multiplex ligation probe amplification (MLPA) and digital droplet polymerase chain reaction (ddPCR), array-CGH and single-nucleotide polymorphism (SNP) arrays, as well as techniques for detection of CNVs using next-generation sequencing data analysis including targeted gene panel, exome, and genome sequencing data. In addition, in this review, we compile published data on pathogenic hearing loss CNVs to provide an up-to-date overview. We show that CNVs have been identified in 29 different non-syndromic hearing loss genes. An understanding of the contribution of CNVs to genetic hearing loss is critical to the current diagnosis of hearing loss and is crucial for future gene therapies. Thus, evaluation for CNVs is required in any modern pipeline for genetic diagnosis of hearing loss.
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Ivanchenko MV, Indzhykulian AA, Corey DP. Electron Microscopy Techniques for Investigating Structure and Composition of Hair-Cell Stereociliary Bundles. Front Cell Dev Biol 2021; 9:744248. [PMID: 34746139 PMCID: PMC8569945 DOI: 10.3389/fcell.2021.744248] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 09/28/2021] [Indexed: 11/18/2022] Open
Abstract
Hair cells—the sensory cells of the vertebrate inner ear—bear at their apical surfaces a bundle of actin-filled protrusions called stereocilia, which mediate the cells’ mechanosensitivity. Hereditary deafness is often associated with morphological disorganization of stereocilia bundles, with the absence or mislocalization within stereocilia of specific proteins. Thus, stereocilia bundles are closely examined to understand most animal models of hereditary hearing loss. Because stereocilia have a diameter less than a wavelength of light, light microscopy is not adequate to reveal subtle changes in morphology or protein localization. Instead, electron microscopy (EM) has proven essential for understanding stereocilia bundle development, maintenance, normal function, and dysfunction in disease. Here we review a set of EM imaging techniques commonly used to study stereocilia, including optimal sample preparation and best imaging practices. These include conventional and immunogold transmission electron microscopy (TEM) and scanning electron microscopy (SEM), as well as focused-ion-beam scanning electron microscopy (FIB-SEM), which enables 3-D serial reconstruction of resin-embedded biological structures at a resolution of a few nanometers. Parameters for optimal sample preparation, fixation, immunogold labeling, metal coating and imaging are discussed. Special attention is given to protein localization in stereocilia using immunogold labeling. Finally, we describe the advantages and limitations of these EM techniques and their suitability for different types of studies.
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Affiliation(s)
- Maryna V Ivanchenko
- Department of Neurobiology, Harvard Medical School, Boston, MA, United States
| | - Artur A Indzhykulian
- Department of Otolaryngology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States
| | - David P Corey
- Department of Neurobiology, Harvard Medical School, Boston, MA, United States
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25
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Han S, Zhang D, Guo Y, Fu Z, Guan G. Prevalence and Characteristics of STRC Gene Mutations (DFNB16): A Systematic Review and Meta-Analysis. Front Genet 2021; 12:707845. [PMID: 34621290 PMCID: PMC8491653 DOI: 10.3389/fgene.2021.707845] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 08/13/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Mutations in the STRC (MIM 606440) gene, inducing DFNB16, are considered a major cause of mild–moderate autosomal recessive non-syndromic hearing loss (ARNSHL). We conducted a systematic review and meta-analysis to determine the global prevalence and characteristics of STRC variations, important information required for genetic counseling. Methods: PubMed, Google Scholar, Medline, Embase, and Web of Science were searched for relevant articles published before January 2021. Results: The pooled prevalence of DFNB16 in GJB2-negative patients with hearing loss was 4.08% (95% CI: 0.0289–0.0573), and the proportion of STRC variants in the mild–moderate hearing loss group was 14.36%. Monoallelic mutations of STRC were 4.84% (95% CI: 0.0343–0.0680) in patients with deafness (non-GJB2) and 1.36% (95% CI: 0.0025–0.0696) in people with normal hearing. The DFNB16 prevalence in genetically confirmed patients (non-GJB2) was 11.10% (95% CI: 0.0716–0.1682). Overall pooled prevalence of deafness–infertility syndrome (DIS) was 36.75% (95% CI: 0.2122–0.5563) in DFNB16. The prevalence of biallelic deletions in STRC gene mutations was 70.85% (95% CI: 0.5824–0.8213). Conclusion: Variants in the STRC gene significantly contribute to mild–moderate hearing impairment. Moreover, biallelic deletions are a main feature of STRC mutations. Copy number variations associated with infertility should be seriously considered when investigating DFNB16.
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Affiliation(s)
- Shuang Han
- Department of Otolaryngology Head and Neck Surgery, The Second Hospital of Jilin University, Changchun, China
| | - Dejun Zhang
- Department of Otolaryngology Head and Neck Surgery, The Second Hospital of Jilin University, Changchun, China
| | - Yingyuan Guo
- Department of Otolaryngology Head and Neck Surgery, The Second Hospital of Jilin University, Changchun, China
| | - Zeming Fu
- Department of Otolaryngology Head and Neck Surgery, The Second Hospital of Jilin University, Changchun, China
| | - Guofang Guan
- Department of Otolaryngology Head and Neck Surgery, The Second Hospital of Jilin University, Changchun, China
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26
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Simi A, Perry J, Schindler E, Oza A, Luo M, Hartman T, Krantz ID, Germiller JA, Kawai K, Kenna M. Audiologic Phenotype and Progression in Pediatric STRC-Related Autosomal Recessive Hearing Loss. Laryngoscope 2021; 131:E2897-E2903. [PMID: 34111299 DOI: 10.1002/lary.29680] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 05/25/2021] [Accepted: 05/28/2021] [Indexed: 11/10/2022]
Abstract
OBJECTIVES Sensorineural hearing loss (SNHL) is a common sensory deficit affecting pediatric populations. The majority of pediatric SNHL is genetic in etiology, with over 123 identified nonsyndromic causative genes. One such gene is STRC, which has been identified as the second most frequent autosomal recessive nonsyndromic gene associated with SNHL in multiple populations. The objective of this study was to investigate the phenotypic presentation and incidence of audiologic progression in pediatric patients with STRC-related hearing loss (HL). METHODS Thirty-nine pediatric patients with confirmed HL and biallelic pathogenic STRC mutations were identified at two pediatric hospitals. A retrospective chart review was completed including demographics, medical history, genetic testing results, and audiologic data. HL progression was assessed using air conduction thresholds from pure-tone audiograms and auditory brain stem responses, and masked bone conduction thresholds from pure-tone audiograms. RESULTS Thirty-six patients had homozygous STRC deletions. Three were compound heterozygotes. All patients had bilateral, symmetric SNHL. Baseline HL was mild in 39% of ears, moderate in 52%, and moderate-severe in 3%. Of the 31 patients for which sufficient data were available to evaluate progression, 18 (58%) had some degree of progressive HL. Among these 31 patients assessed for progression, the mean hearing threshold declined by 0.6 dB per year (95% confidence interval: 0.5, 0.8; P < .001). CONCLUSIONS These biallelic STRC patients displayed HL ranging from mild to moderate-severe at baseline and progressing in 58%. The variability of the STRC phenotype and the possibility of audiologic progression should be considered in the clinical management of pediatric STRC-related SNHL. LEVEL OF EVIDENCE 3 Laryngoscope, 2021.
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Affiliation(s)
- Andrea Simi
- Department of Otolaryngology and Communication Enhancement, Boston Children's Hospital, Boston, Massachusetts, U.S.A.,Case Western Reserve University School of Medicine, Cleveland, Ohio, U.S.A
| | - Julia Perry
- Department of Otolaryngology and Communication Enhancement, Boston Children's Hospital, Boston, Massachusetts, U.S.A
| | - Emma Schindler
- Department of Otorhinolaryngology, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A
| | - Andrea Oza
- Department of Otolaryngology and Communication Enhancement, Boston Children's Hospital, Boston, Massachusetts, U.S.A.,Laboratory for Molecular Medicine, Partners HealthCare Personalized Medicine, Cambridge, Massachusetts, U.S.A
| | - Minjie Luo
- Division of Genomic Diagnostics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, U.S.A.,Department of Pathology, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A
| | - Tiffiney Hartman
- Roberts Individualized Medical Genetics Center, Division of Genetics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, U.S.A
| | - Ian D Krantz
- Roberts Individualized Medical Genetics Center, Division of Genetics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, U.S.A.,Department of Pediatrics, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A
| | - John A Germiller
- Department of Otorhinolaryngology, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.,Division of Otolaryngology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, U.S.A
| | - Kosuke Kawai
- Department of Otolaryngology and Communication Enhancement, Boston Children's Hospital, Boston, Massachusetts, U.S.A.,Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts, U.S.A
| | - Margaret Kenna
- Department of Otolaryngology and Communication Enhancement, Boston Children's Hospital, Boston, Massachusetts, U.S.A.,Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts, U.S.A
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27
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Hakizimana P, Fridberger A. Inner hair cell stereocilia are embedded in the tectorial membrane. Nat Commun 2021; 12:2604. [PMID: 33972539 PMCID: PMC8110531 DOI: 10.1038/s41467-021-22870-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 04/06/2021] [Indexed: 02/03/2023] Open
Abstract
Mammalian hearing depends on sound-evoked displacements of the stereocilia of inner hair cells (IHCs), which cause the endogenous mechanoelectrical transducer channels to conduct inward currents of cations including Ca2+. Due to their presumed lack of contacts with the overlaying tectorial membrane (TM), the putative stimulation mechanism for these stereocilia is by means of the viscous drag of the surrounding endolymph. However, despite numerous efforts to characterize the TM by electron microscopy and other techniques, the exact IHC stereocilia-TM relationship remains elusive. Here we show that Ca2+-rich filamentous structures, that we call Ca2+ ducts, connect the TM to the IHC stereocilia to enable mechanical stimulation by the TM while also ensuring the stereocilia access to TM Ca2+. Our results call for a reassessment of the stimulation mechanism for the IHC stereocilia and the TM role in hearing.
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Affiliation(s)
- Pierre Hakizimana
- grid.5640.70000 0001 2162 9922Department of Biomedical and Clinical Sciences (BKV), Linköping University, Linköping, Sweden
| | - Anders Fridberger
- grid.5640.70000 0001 2162 9922Department of Biomedical and Clinical Sciences (BKV), Linköping University, Linköping, Sweden
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28
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Escalera-Balsera A, Roman-Naranjo P, Lopez-Escamez JA. Systematic Review of Sequencing Studies and Gene Expression Profiling in Familial Meniere Disease. Genes (Basel) 2020; 11:E1414. [PMID: 33260921 PMCID: PMC7761472 DOI: 10.3390/genes11121414] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/21/2020] [Accepted: 11/25/2020] [Indexed: 02/06/2023] Open
Abstract
Familial Meniere Disease (FMD) is a rare inner ear disorder characterized by episodic vertigo associated with sensorineural hearing loss, tinnitus and/or aural fullness. We conducted a systematic review to find sequencing studies segregating rare variants in FMD to obtain evidence to support candidate genes for MD. After evaluating the quality of the retrieved records, eight studies were selected to carry out a quantitative synthesis. These articles described 20 single nucleotide variants (SNVs) in 11 genes (FAM136A, DTNA, PRKCB, COCH, DPT, SEMA3D, STRC, HMX2, TMEM55B, OTOG and LSAMP), most of them in singular families-the exception being the OTOG gene. Furthermore, we analyzed the pathogenicity of each SNV and compared its allelic frequency with reference datasets to evaluate its role in the pathogenesis of FMD. By retrieving gene expression data in these genes from different databases, we could classify them according to their gene expression in neural or inner ear tissues. Finally, we evaluated the pattern of inheritance to conclude which genes show an autosomal dominant (AD) or autosomal recessive (AR) inheritance in FMD.
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Affiliation(s)
- Alba Escalera-Balsera
- Otology & Neurotology Group CTS 495, Department of Genomic Medicine, Centro Pfizer-Universidad de Granada-Junta de Andalucía de Genómica e Investigación Oncológica, 18016 Granada, Spain; (A.E.-B.); (P.R.-N.)
| | - Pablo Roman-Naranjo
- Otology & Neurotology Group CTS 495, Department of Genomic Medicine, Centro Pfizer-Universidad de Granada-Junta de Andalucía de Genómica e Investigación Oncológica, 18016 Granada, Spain; (A.E.-B.); (P.R.-N.)
| | - Jose Antonio Lopez-Escamez
- Otology & Neurotology Group CTS 495, Department of Genomic Medicine, Centro Pfizer-Universidad de Granada-Junta de Andalucía de Genómica e Investigación Oncológica, 18016 Granada, Spain; (A.E.-B.); (P.R.-N.)
- Department of Otolaryngology, Instituto de Investigación Biosanitaria, ibs.GRANADA, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain
- Department of Surgery, Division of Otolaryngology, Universidad de Granada, 18016 Granada, Spain
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29
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Clinical features of hearing loss caused by STRC gene deletions/mutations in Russian population. Int J Pediatr Otorhinolaryngol 2020; 138:110247. [PMID: 32705992 DOI: 10.1016/j.ijporl.2020.110247] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/02/2020] [Accepted: 07/02/2020] [Indexed: 12/29/2022]
Abstract
UNLABELLED Congenital sensorineural hearing loss is related to mutations in numerous genes encoding the structures of the inner ear in majority of the cases. Mutations in GJB2 gene are the most frequently identified causes of congenital nonsyndromal hearing loss. GJB2 gene testing became a routine clinical tool. For GJB2-negative patients new genetic approaches including methods based on new generation sequencing give a chance to identify mutations in other genes. The frequent reason of mild-to-moderate hearing loss such as the deletions/mutations of the gene STRC encoding stereocilin protein were recognized (OMIM: 606440). OBJECTIVES To evaluate the audiological features in hearing impaired patients with deletions and point mutations in the STRC gene. PATIENTS AND METHODS The group of 28 patients from 21 unrelated families with pathological mutations in the STRC gene underwent audiological examination. The description and analysis of the results of full audiological examination was provided. RESULTS All patients initially had bilateral nonsyndromal sensorineural hearing loss. Among 11 homozygotes of large deletion harboring STRC to CATSPER2 genes were 7 male individuals indicating the presence of male infertility syndrome. In general, 7 children failed audiological screening and 4 children underwent audiological assessment in the age of 3 and 6 months. The most frequently hearing thresholds were registered between 35 and 55 dB that corresponds to mild-to-moderate hearing impairment. The average age of diagnostics was 7.9 years (ranged from 3 months to 45 years). In the majority of patients the audiological profiles were flat or descending with elevation of thresholds at middle and high frequencies and relatively preserved thresholds at low frequencies. Hearing thresholds are symmetric and stable with age. CONCLUSION STRC-linked hearing loss is congenital, of mild and moderate severity. Special clinical and genetic approach for children who failed newborn hearing screening with mild-to-moderate hearing loss is necessary.
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30
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Whatley M, Francis A, Ng ZY, Khoh XE, Atlas MD, Dilley RJ, Wong EYM. Usher Syndrome: Genetics and Molecular Links of Hearing Loss and Directions for Therapy. Front Genet 2020; 11:565216. [PMID: 33193648 PMCID: PMC7642844 DOI: 10.3389/fgene.2020.565216] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 09/21/2020] [Indexed: 12/19/2022] Open
Abstract
Usher syndrome (USH) is an autosomal recessive (AR) disorder that permanently and severely affects the senses of hearing, vision, and balance. Three clinically distinct types of USH have been identified, decreasing in severity from Type 1 to 3, with symptoms of sensorineural hearing loss (SNHL), retinitis pigmentosa (RP), and vestibular dysfunction. There are currently nine confirmed and two suspected USH-causative genes, and a further three candidate loci have been mapped. The proteins encoded by these genes form complexes that play critical roles in the development and maintenance of cellular structures within the inner ear and retina, which have minimal capacity for repair or regeneration. In the cochlea, stereocilia are located on the apical surface of inner ear hair cells (HC) and are responsible for transducing mechanical stimuli from sound pressure waves into chemical signals. These signals are then detected by the auditory nerve fibers, transmitted to the brain and interpreted as sound. Disease-causing mutations in USH genes can destabilize the tip links that bind the stereocilia to each other, and cause defects in protein trafficking and stereocilia bundle morphology, thereby inhibiting mechanosensory transduction. This review summarizes the current knowledge on Usher syndrome with a particular emphasis on mutations in USH genes, USH protein structures, and functional analyses in animal models. Currently, there is no cure for USH. However, the genetic therapies that are rapidly developing will benefit from this compilation of detailed genetic information to identify the most effective strategies for restoring functional USH proteins.
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Affiliation(s)
- Meg Whatley
- Ear Science Institute Australia, Nedlands, WA, Australia
| | - Abbie Francis
- Ear Science Institute Australia, Nedlands, WA, Australia
- Emergency Medicine, The University of Western Australia, Nedlands, WA, Australia
| | - Zi Ying Ng
- Ear Science Institute Australia, Nedlands, WA, Australia
| | - Xin Ee Khoh
- Ear Science Institute Australia, Nedlands, WA, Australia
- School of Human Sciences, The University of Western Australia, Nedlands, WA, Australia
| | - Marcus D. Atlas
- Ear Science Institute Australia, Nedlands, WA, Australia
- Ear Sciences Centre, The University of Western Australia, Nedlands, WA, Australia
| | - Rodney J. Dilley
- Ear Science Institute Australia, Nedlands, WA, Australia
- Ear Sciences Centre, The University of Western Australia, Nedlands, WA, Australia
- Centre for Cell Therapy and Regenerative Medicine, The University of Western Australia, Perth, WA, Australia
| | - Elaine Y. M. Wong
- Ear Science Institute Australia, Nedlands, WA, Australia
- Ear Sciences Centre, The University of Western Australia, Nedlands, WA, Australia
- School of Pharmacy and Biomedical Sciences, Faculty of Health Sciences, Curtin University, Bentley, WA, Australia
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31
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Interaction of protocadherin-15 with the scaffold protein whirlin supports its anchoring of hair-bundle lateral links in cochlear hair cells. Sci Rep 2020; 10:16430. [PMID: 33009420 PMCID: PMC7532178 DOI: 10.1038/s41598-020-73158-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 09/07/2020] [Indexed: 11/26/2022] Open
Abstract
The hair bundle of cochlear hair cells is the site of auditory mechanoelectrical transduction. It is formed by three rows of stiff microvilli-like protrusions of graduated heights, the short, middle-sized, and tall stereocilia. In developing and mature sensory hair cells, stereocilia are connected to each other by various types of fibrous links. Two unconventional cadherins, protocadherin-15 (PCDH15) and cadherin-23 (CDH23), form the tip-links, whose tension gates the hair cell mechanoelectrical transduction channels. These proteins also form transient lateral links connecting neighboring stereocilia during hair bundle morphogenesis. The proteins involved in anchoring these diverse links to the stereocilia dense actin cytoskeleton remain largely unknown. We show that the long isoform of whirlin (L-whirlin), a PDZ domain-containing submembrane scaffold protein, is present at the tips of the tall stereocilia in mature hair cells, together with PCDH15 isoforms CD1 and CD2; L-whirlin localization to the ankle-link region in developing hair bundles moreover depends on the presence of PCDH15-CD1 also localizing there. We further demonstrate that L-whirlin binds to PCDH15 and CDH23 with moderate-to-high affinities in vitro. From these results, we suggest that L-whirlin is part of the molecular complexes bridging PCDH15-, and possibly CDH23-containing lateral links to the cytoskeleton in immature and mature stereocilia.
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32
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Pyott SJ, van Tuinen M, Screven LA, Schrode KM, Bai JP, Barone CM, Price SD, Lysakowski A, Sanderford M, Kumar S, Santos-Sacchi J, Lauer AM, Park TJ. Functional, Morphological, and Evolutionary Characterization of Hearing in Subterranean, Eusocial African Mole-Rats. Curr Biol 2020; 30:4329-4341.e4. [PMID: 32888484 DOI: 10.1016/j.cub.2020.08.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 06/09/2020] [Accepted: 08/07/2020] [Indexed: 12/26/2022]
Abstract
Naked mole-rats are highly vocal, eusocial, subterranean rodents with, counterintuitively, poor hearing. The causes underlying their altered hearing are unknown. Moreover, whether altered hearing is degenerate or adaptive to their unique lifestyles is controversial. We used various methods to identify the factors contributing to altered hearing in naked and the related Damaraland mole-rats and to examine whether these alterations result from relaxed or adaptive selection. Remarkably, we found that cochlear amplification was absent from both species despite normal prestin function in outer hair cells isolated from naked mole-rats. Instead, loss of cochlear amplification appears to result from abnormal hair bundle morphologies observed in both species. By exploiting a well-curated deafness phenotype-genotype database, we identified amino acid substitutions consistent with abnormal hair bundle morphology and reduced hearing sensitivity. Amino acid substitutions were found in unique groups of six hair bundle link proteins. Molecular evolutionary analyses revealed shifts in selection pressure at both the gene and the codon level for five of these six hair bundle link proteins. Substitutions in three of these proteins are associated exclusively with altered hearing. Altogether, our findings identify the likely mechanism of altered hearing in African mole-rats, making them the only identified mammals naturally lacking cochlear amplification. Moreover, our findings suggest that altered hearing in African mole-rats is adaptive, perhaps tailoring hearing to eusocial and subterranean lifestyles. Finally, our work reveals multiple, unique evolutionary trajectories in African mole-rat hearing and establishes species members as naturally occurring disease models to investigate human hearing loss.
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Affiliation(s)
- Sonja J Pyott
- University Medical Center Groningen and University of Groningen, Department of Otorhinolaryngology and Head/Neck Surgery, 9713GZ Groningen, the Netherlands.
| | - Marcel van Tuinen
- University Medical Center Groningen and University of Groningen, Department of Otorhinolaryngology and Head/Neck Surgery, 9713GZ Groningen, the Netherlands
| | - Laurel A Screven
- Johns Hopkins School of Medicine, Department of Otolaryngology, Baltimore, MD 21205, USA
| | - Katrina M Schrode
- Johns Hopkins School of Medicine, Department of Otolaryngology, Baltimore, MD 21205, USA
| | - Jun-Ping Bai
- Yale University School of Medicine, Department of Neurology, 333 Cedar Street, New Haven, CT 06510, USA
| | - Catherine M Barone
- University of Illinois at Chicago, Department of Biological Sciences, Chicago, IL 60612, USA
| | - Steven D Price
- University of Illinois at Chicago, Department of Anatomy and Cell Biology, Chicago, IL 60612, USA
| | - Anna Lysakowski
- University of Illinois at Chicago, Department of Anatomy and Cell Biology, Chicago, IL 60612, USA
| | - Maxwell Sanderford
- Temple University, Institute for Genomics and Evolutionary Medicine and Department of Biology, Philadelphia, PA 19122, USA
| | - Sudhir Kumar
- Temple University, Institute for Genomics and Evolutionary Medicine and Department of Biology, Philadelphia, PA 19122, USA; King Abdulaziz University, Center for Excellence in Genome Medicine and Research, Jeddah, Saudi Arabia
| | - Joseph Santos-Sacchi
- Yale University School of Medicine, Department of Surgery (Otolaryngology) and Department of Neuroscience and Cellular and Molecular Physiology, 333 Cedar Street, New Haven, CT 06510, USA
| | - Amanda M Lauer
- Johns Hopkins School of Medicine, Department of Otolaryngology, Baltimore, MD 21205, USA
| | - Thomas J Park
- University of Illinois at Chicago, Department of Biological Sciences, Chicago, IL 60612, USA
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33
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Markova TG, Alekseeva NN, Mironovich OL, Bliznets EA, Lalayants MR, Polyakov AV, Tavartkiladze GA. [Hearing loss due to mutations or lack of the gene coding protein stereocillin]. Vestn Otorinolaringol 2020; 85:14-20. [PMID: 32476383 DOI: 10.17116/otorino20208502114] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE The description of a clinical picture and audiological features at the hearing loss caused by changes of a STRC gene, coding protein stereocillin (MIM: 606440). Mutations in the numerous genes responsible for the inner ear proteins are the reason for congenital sensorineural hearing loss. The main cause of congenital bilateral sensorineural hearing loss in the Russian Federation are mutations in GJB2 gene it reaches up 68% of cases identified in infancy. GJB2 gene tests already became routine around the world. Possibilities of new methods based on sequencing of new generation (NGS, next generation sequencing) allow to conduct a research of more rare genes connected with a hearing impairment. The most often among GJB2 negative patients reveal mutations and deletion of a gene of STRC. PATIENTS AND METHODS Full audiological examination of 5 children and one adult with a hearing loss from 2 unrelated families is provided. Mutations in STRC gene were identified. All children are examined aged before 8 years, and 3 children failed universal audiological screening in maternity hospital, to two children screening was not carried out as they were born till 2009. RESULTS The children with the sensorineural hearing loss connected with mutations and deletion of STRC gene failed hearing screening in maternity hospital because of the OAE is not registered, what indicates the congenital nature of a hearing loss. Recently it could not be noticed earlier because of slight increase of hearing thresholds and was regarded only as the early onset. Our data emphasize that the of thresholds from 35 to 60 dB in frequencies 0,5-4 kHz is common for mutations/deletions of STRC gene. CONCLUSION The development of molecular genetics methods confirms the hereditary causes of GJB2-negative patients and expands indications for family counseling. Special approach for child with hearing loss so early revealed is necessary and the consultation of parents frightened of screening results is very important.
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Affiliation(s)
- T G Markova
- National Resarch Center for Audiology and Hearing Rehabilitation, Moscow, Russia.,Russian Medical Academy of Postdoctoral Education of the Ministry of Health of Russia, Moscow, Russia
| | - N N Alekseeva
- National Resarch Center for Audiology and Hearing Rehabilitation, Moscow, Russia.,Russian Medical Academy of Postdoctoral Education of the Ministry of Health of Russia, Moscow, Russia
| | - O L Mironovich
- Academician N.P. Bochkov Medical and Genetic Research Center, Moscow, Russia
| | - E A Bliznets
- Academician N.P. Bochkov Medical and Genetic Research Center, Moscow, Russia
| | - M R Lalayants
- National Resarch Center for Audiology and Hearing Rehabilitation, Moscow, Russia.,Russian Medical Academy of Postdoctoral Education of the Ministry of Health of Russia, Moscow, Russia
| | - A V Polyakov
- Academician N.P. Bochkov Medical and Genetic Research Center, Moscow, Russia
| | - G A Tavartkiladze
- National Resarch Center for Audiology and Hearing Rehabilitation, Moscow, Russia.,Russian Medical Academy of Postdoctoral Education of the Ministry of Health of Russia, Moscow, Russia
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34
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Ivanchenko MV, Cicconet M, Jandal HA, Wu X, Corey DP, Indzhykulian AA. Serial scanning electron microscopy of anti-PKHD1L1 immuno-gold labeled mouse hair cell stereocilia bundles. Sci Data 2020; 7:182. [PMID: 32555200 PMCID: PMC7299942 DOI: 10.1038/s41597-020-0509-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 04/30/2020] [Indexed: 11/11/2022] Open
Abstract
Serial electron microscopy techniques have proven to be a powerful tool in biology. Unfortunately, the data sets they generate lack robust and accurate automated segmentation algorithms. In this data descriptor publication, we introduce a serial focused ion beam scanning electron microscopy (FIB-SEM) dataset consisting of six outer hair cell (OHC) stereocilia bundles, and the supranuclear part of the hair cell bodies. Also presented are the manual segmentations of stereocilia bundles and the gold bead labeling of PKHD1L1, a coat protein of hair cell stereocilia important for hearing in mice. This depository includes all original data and several intermediate steps of the manual analysis, as well as the MATLAB algorithm used to generate a three-dimensional distribution map of gold labels. They serve as a reference dataset, and they enable reproduction of our analysis, evaluation and improvement of current methods of protein localization, and training of algorithms for accurate automated segmentation.
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Affiliation(s)
- Maryna V Ivanchenko
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA, 02115, USA
| | - Marcelo Cicconet
- Image and Data Analysis Core, Harvard Medical School, 43 Shattuck St, Boston, MA, 02115, USA
| | - Hoor Al Jandal
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA, 02115, USA
- Northeastern University, 360 Huntington Avenue, Boston, MA, 02115, USA
| | - Xudong Wu
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA, 02115, USA
| | - David P Corey
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA, 02115, USA
| | - Artur A Indzhykulian
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA, 02115, USA.
- Department of Otolaryngology, Harvard Medical School and Massachusetts Eye and Ear, 243 Charles St, Boston, MA, 02114, USA.
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35
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Khela H, Kenna MA. Genetics of pediatric hearing loss: A functional perspective. Laryngoscope Investig Otolaryngol 2020; 5:511-519. [PMID: 32596495 PMCID: PMC7314484 DOI: 10.1002/lio2.390] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 04/02/2020] [Accepted: 04/15/2020] [Indexed: 12/14/2022] Open
Abstract
OBJECTIVES This article reviews the current role of genetics in pediatric hearing loss (HL). METHODS A review of the current literature regarding the genetic basis of HL in children was performed. RESULTS To date, 119 nonsyndromic genes have been associated with HL. There are also hundreds of syndromic causes that have HL as part of the clinical phenotype. CONCLUSIONS Identifying HL genes coupled with clinical characteristics ("genotype-phenotype") yields a more accurate diagnosis and prognosis. Although the complexity of the auditory apparatus presents challenges, gene therapy is emerging and may be a viable management option in the future.
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Affiliation(s)
- Harmon Khela
- Summer Scholars Program, Otolaryngology and Communication Enhancement, Boston Children's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Margaret A. Kenna
- Department of Otolaryngology and Communication EnhancementBoston Children's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
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36
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Distinct roles of stereociliary links in the nonlinear sound processing and noise resistance of cochlear outer hair cells. Proc Natl Acad Sci U S A 2020; 117:11109-11117. [PMID: 32358189 DOI: 10.1073/pnas.1920229117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Outer hair cells (OHCs) play an essential role in hearing by acting as a nonlinear amplifier which helps the cochlea detect sounds with high sensitivity and accuracy. This nonlinear sound processing generates distortion products, which can be measured as distortion-product otoacoustic emissions (DPOAEs). The OHC stereocilia that respond to sound vibrations are connected by three kinds of extracellular links: tip links that connect the taller stereocilia to shorter ones and convey force to the mechanoelectrical transduction channels, tectorial membrane-attachment crowns (TM-ACs) that connect the tallest stereocilia to one another and to the overlying TM, and horizontal top connectors (HTCs) that link adjacent stereocilia. While the tip links have been extensively studied, the roles that the other two types of links play in hearing are much less clear, largely because of a lack of suitable animal models. Here, while analyzing genetic combinations of tubby mice, we encountered models missing both HTCs and TM-ACs or HTCs alone. We found that the tubby mutation causes loss of both HTCs and TM-ACs due to a mislocalization of stereocilin, which results in OHC dysfunction leading to severe hearing loss. Intriguingly, the addition of the modifier allele modifier of tubby hearing 1 in tubby mice selectively rescues the TM-ACs but not the HTCs. Hearing is significantly rescued in these mice with robust DPOAE production, indicating an essential role of the TM-ACs but not the HTCs in normal OHC function. In contrast, the HTCs are required for the resistance of hearing to damage caused by noise stress.
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37
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Abstract
In children with normal hearing, inflammatory disorders caused by infections of the middle ear (otitis media) are the most common ear illnesses. Many of older adults experience some level of hearing loss. Several factors can lead to either a partial loss or the total inability to hear (deafness) including exposure to noise, a hereditary predisposition, chronic infections, traumas, medications, and aging.
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Richardson GP, Petit C. Hair-Bundle Links: Genetics as the Gateway to Function. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a033142. [PMID: 30617060 DOI: 10.1101/cshperspect.a033142] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Up to five distinct cell-surface specializations interconnect the stereocilia and the kinocilium of the mature hair bundle in some species: kinocilial links, tip links, top connectors, shaft connectors, and ankle links. In developing hair bundles, transient lateral links are prominent. Mutations in genes encoding proteins associated with these links cause Usher deafness/blindness syndrome or nonsyndromic (isolated) forms of human hereditary deafness, and mice with constitutive or conditional alleles of these genes have provided considerable insight into the molecular composition and function of the different links. We describe the structure of these links and review evidence showing CDH23 and PCDH15 are components of the tip, kinocilial, and transient-lateral links, that stereocilin (STRC) and protein tyrosine phosphatase (PTPRQ) are associated with top and shaft connectors, respectively, and that USH2A and ADGRV1 are associated with the ankle links. Whereas tip links are required for mechanoelectrical transduction, all link proteins play key roles in the normal development and/or the maintenance of hair bundle structure and function. Recent crystallographic and single-particle analyses of PCDH15 and CDH23 provide insight as to how the structure of tip link may contribute to the elastic element predicted to lie in series with the hair cell's mechanoelectrical transducer channel.
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Affiliation(s)
- Guy P Richardson
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom
| | - Christine Petit
- Institut Pasteur, 75724 Paris Cedex 15, France.,Collège de France, 75231 Paris Cedex 05, France
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Otogelin, otogelin-like, and stereocilin form links connecting outer hair cell stereocilia to each other and the tectorial membrane. Proc Natl Acad Sci U S A 2019; 116:25948-25957. [PMID: 31776257 DOI: 10.1073/pnas.1902781116] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The function of outer hair cells (OHCs), the mechanical actuators of the cochlea, involves the anchoring of their tallest stereocilia in the tectorial membrane (TM), an acellular structure overlying the sensory epithelium. Otogelin and otogelin-like are TM proteins related to secreted epithelial mucins. Defects in either cause the DFNB18B and DFNB84B genetic forms of deafness, respectively, both characterized by congenital mild-to-moderate hearing impairment. We show here that mutant mice lacking otogelin or otogelin-like have a marked OHC dysfunction, with almost no acoustic distortion products despite the persistence of some mechanoelectrical transduction. In both mutants, these cells lack the horizontal top connectors, which are fibrous links joining adjacent stereocilia, and the TM-attachment crowns coupling the tallest stereocilia to the TM. These defects are consistent with the previously unrecognized presence of otogelin and otogelin-like in the OHC hair bundle. The defective hair bundle cohesiveness and the absence of stereociliary imprints in the TM observed in these mice have also been observed in mutant mice lacking stereocilin, a model of the DFNB16 genetic form of deafness, also characterized by congenital mild-to-moderate hearing impairment. We show that the localizations of stereocilin, otogelin, and otogelin-like in the hair bundle are interdependent, indicating that these proteins interact to form the horizontal top connectors and the TM-attachment crowns. We therefore suggest that these 2 OHC-specific structures have shared mechanical properties mediating reaction forces to sound-induced shearing motion and contributing to the coordinated displacement of stereocilia.
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40
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Čada Z, Šafka Brožková D, Balatková Z, Plevová P, Rašková D, Laštůvková J, Černý R, Bandúrová V, Koucký V, Hrubá S, Komarc M, Jenčík J, Poisson Marková S, Plzák J, Kluh J, Seeman P. Moderate sensorineural hearing loss is typical for DFNB16 caused by various types of mutations affecting the STRC gene. Eur Arch Otorhinolaryngol 2019; 276:3353-3358. [DOI: 10.1007/s00405-019-05649-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Accepted: 09/11/2019] [Indexed: 01/13/2023]
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41
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Ito T, Kawashima Y, Fujikawa T, Honda K, Makabe A, Kitamura K, Tsutsumi T. Rapid screening of copy number variations in STRC by droplet digital PCR in patients with mild-to-moderate hearing loss. Hum Genome Var 2019; 6:41. [PMID: 31645979 PMCID: PMC6804619 DOI: 10.1038/s41439-019-0075-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 11/09/2022] Open
Abstract
Copy number variations (CNVs) are commonly reported in STRC, the causal gene for DFNB16. Various techniques are used clinically for CNV detection, and droplet digital PCR (ddPCR) provides highly precise absolute quantification of DNA copy number. We aimed to validate the feasibility and efficiency of ddPCR in combination with long-range PCR (LR-PCR) in identifying CNVs and mutations in STRC. Additionally, we determined the frequency of CNVs and mutations in STRC in Japanese patients with mild-to-moderate hearing loss. We evaluated 84 unrelated Japanese patients with mild-to-moderate bilateral idiopathic or autosomal recessive nonsyndromic sensorineural hearing loss. The ratio of STRC copy number to the copy number of the internal control RPP30 ranged from 0.949 to 1.009 (0.989 ± 0.017) in 77 patients; it ranged from 0.484 to 0.538 (0.509 ± 0.024) in five patients and was 0.000 in two patients, indicating heterozygous and homozygous deletions, respectively. The copy number deletion prevalence rates were 7.7% and 0.9% in the patients and healthy controls, respectively. In combination with LR-PCR, ddPCR revealed that at least three patients (3.6%) had STRC-related hearing loss. Detecting STRC CNVs by ddPCR was rapid, precise, and cost-effective and facilitated the identification of STRC CNVs.
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Affiliation(s)
- Taku Ito
- 1Department of Otorhinolaryngology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yoshiyuki Kawashima
- 1Department of Otorhinolaryngology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Taro Fujikawa
- 1Department of Otorhinolaryngology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Keiji Honda
- 1Department of Otorhinolaryngology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Ayane Makabe
- 1Department of Otorhinolaryngology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Ken Kitamura
- 1Department of Otorhinolaryngology, Tokyo Medical and Dental University, Tokyo, Japan.,Department of Otorhinolaryngology, Head and Neck Surgery, Chigasaki Chuo Hospital, Chigasaki, Japan
| | - Takeshi Tsutsumi
- 1Department of Otorhinolaryngology, Tokyo Medical and Dental University, Tokyo, Japan
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42
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PKHD1L1 is a coat protein of hair-cell stereocilia and is required for normal hearing. Nat Commun 2019; 10:3801. [PMID: 31444330 PMCID: PMC6707252 DOI: 10.1038/s41467-019-11712-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 06/28/2019] [Indexed: 12/18/2022] Open
Abstract
The bundle of stereocilia on inner ear hair cells responds to subnanometer deflections produced by sound or head movement. Stereocilia are interconnected by a variety of links and also carry an electron-dense surface coat. The coat may contribute to stereocilia adhesion or protect from stereocilia fusion, but its molecular identity remains unknown. From a database of hair-cell-enriched translated proteins, we identify Polycystic Kidney and Hepatic Disease 1-Like 1 (PKHD1L1), a large, mostly extracellular protein of 4249 amino acids with a single transmembrane domain. Using serial immunogold scanning electron microscopy, we show that PKHD1L1 is expressed at the tips of stereocilia, especially in the high-frequency regions of the cochlea. PKHD1L1-deficient mice lack the surface coat at the upper but not lower regions of stereocilia, and they develop progressive hearing loss. We conclude that PKHD1L1 is a component of the surface coat and is required for normal hearing in mice. There is little known about the function or molecular identity of the electron-dense stereocilia coat, which is transiently present at the surface of stereocilia. In this study authors screened a database of hair-cell-enriched translated proteins to identify the expression of Polycystic Kidney and Hepatic Disease 1-Like 1 (PKHD1L1), a large, mostly extracellular protein, and show that it forms the coat at the tips of stereocilia and is required for normal hearing in mice
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43
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OHC-TRECK: A Novel System Using a Mouse Model for Investigation of the Molecular Mechanisms Associated with Outer Hair Cell Death in the Inner Ear. Sci Rep 2019; 9:5285. [PMID: 30918314 PMCID: PMC6437180 DOI: 10.1038/s41598-019-41711-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 03/15/2019] [Indexed: 12/20/2022] Open
Abstract
Outer hair cells (OHCs) are responsible for the amplification of sound, and the death of these cells leads to hearing loss. Although the mechanisms for sound amplification and OHC death have been well investigated, the effects on the cochlea after OHC death are poorly understood. To study the consequences of OHC death, we established an OHC knockout system using a novel mouse model, Prestin-hDTR, which uses the prestin promoter to express the human diphtheria toxin (DT) receptor gene (hDTR). Administration of DT to adult Prestin-hDTR mice results in the depletion of almost all OHCs without significant damage to other cochlear and vestibular cells, suggesting that this system is an effective tool for the analysis of how other cells in the cochlea and vestibula are affected after OHC death. To evaluate the changes in the cochlea after OHC death, we performed differential gene expression analysis between the untreated and DT-treated groups of wild-type and Prestin-hDTR mice. This analysis revealed that genes associated with inflammatory/immune responses were significantly upregulated. Moreover, we found that several genes linked to hearing loss were strongly downregulated by OHC death. Together, these results suggest that this OHC knockout system is a useful tool to identify biomarkers associated with OHC death.
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44
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Yokota Y, Moteki H, Nishio SY, Yamaguchi T, Wakui K, Kobayashi Y, Ohyama K, Miyazaki H, Matsuoka R, Abe S, Kumakawa K, Takahashi M, Sakaguchi H, Uehara N, Ishino T, Kosho T, Fukushima Y, Usami SI. Frequency and clinical features of hearing loss caused by STRC deletions. Sci Rep 2019; 9:4408. [PMID: 30867468 PMCID: PMC6416315 DOI: 10.1038/s41598-019-40586-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 02/19/2019] [Indexed: 12/04/2022] Open
Abstract
Sensorineural hearing loss is a common deficit and mainly occurs due to genetic factors. Recently, copy number variants (CNVs) in the STRC gene have also been recognized as a major cause of genetic hearing loss. We investigated the frequency of STRC deletions in the Japanese population and the characteristics of associated hearing loss. For CNV analysis, we employed a specialized method of Ion AmpliSeqTM sequencing, and confirmed the CNV results via custom array comparative genomic hybridization. We identified 17 probands with STRC homozygous deletions. The prevalence of STRC homozygous deletions was 1.7% in the hearing loss population overall, and 4.3% among mild-to-moderate hearing loss patients. A 2.63% carrier deletion rate was identified in both the hearing loss and the control population with normal hearing. In conclusion, our results show that STRC deletions are the second most common cause of mild-to-moderate hearing loss after the GJB2 gene, which accounts for the majority of genetic hearing loss. The phenotype of hearing loss is congenital and appears to be moderate, and is most likely to be stable without deterioration even after the age of 50. The present study highlights the importance of the STRC gene as a major cause of mild-to-moderate hearing loss.
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Affiliation(s)
- Yoh Yokota
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Hideaki Moteki
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan. .,Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan.
| | - Shin-Ya Nishio
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan.,Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
| | - Tomomi Yamaguchi
- Department of Medical Genetics, Shinshu University School of Medicine, Matsumoto, Japan.,Center for Medical Genetics, Shinshu University Hospital, Matsumoto, Japan
| | - Keiko Wakui
- Department of Medical Genetics, Shinshu University School of Medicine, Matsumoto, Japan.,Center for Medical Genetics, Shinshu University Hospital, Matsumoto, Japan
| | - Yumiko Kobayashi
- Department of Otolaryngology-Head & Neck Surgery, Iwate Medical University, Morioka, Japan
| | - Kenji Ohyama
- Department of Otorhinolaryngology, Tohoku Rosai Hospital, Sendai, Japan
| | - Hiromitsu Miyazaki
- Department of Otorhinolaryngology-Head and Neck Surgery, Tohoku University School of Medicine, Sendai, Japan
| | - Rina Matsuoka
- Department of Otorhinolaryngology, Juntendo University Faculty of Medicine, Tokyo, Japan
| | - Satoko Abe
- Department of Otorhinolaryngology, Toranomon Hospital, Tokyo, Japan
| | - Kozo Kumakawa
- Department of Otorhinolaryngology, Toranomon Hospital, Tokyo, Japan
| | - Masahiro Takahashi
- Department of Otorhinolaryngology, Head and Neck Surgery, Yokohama City University School of Medicine, Yokohama, Japan.,Department of Otorhinolaryngology, International University of Health and Welfare, Mita Hospital, Tokyo, Japan
| | - Hirofumi Sakaguchi
- Department of Otorhinolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Natsumi Uehara
- Department of Otolaryngology-Head and Neck Surgery, Kobe University School of Medicine, Kobe, Japan
| | - Takashi Ishino
- Department of Otorhinolaryngology, Head and Neck Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Tomoki Kosho
- Department of Medical Genetics, Shinshu University School of Medicine, Matsumoto, Japan.,Center for Medical Genetics, Shinshu University Hospital, Matsumoto, Japan.,Research Center for Support to Advanced Science, Shinshu University, Matsumoto, Japan
| | | | - Shin-Ichi Usami
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan.,Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
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45
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Abstract
A new mechanism that contributes to control of hearing sensitivity is described here. We show that an accessory structure in the hearing organ, the tectorial membrane, affects the function of inner ear sensory cells by storing calcium ions. When the calcium store is depleted, by brief exposure to rock concert-level sounds or by the introduction of calcium chelators, the sound-evoked responses of the sensory cells decrease. Upon restoration of tectorial membrane calcium, sensory cell function returns. This previously unknown mechanism contributes to explaining the temporary numbness in the ear that follows from listening to sounds that are too loud, a phenomenon that most people experience at some point in their lives. When sound stimulates the stereocilia on the sensory cells in the hearing organ, Ca2+ ions flow through mechanically gated ion channels. This Ca2+ influx is thought to be important for ensuring that the mechanically gated channels operate within their most sensitive response region, setting the fraction of channels open at rest, and possibly for the continued maintenance of stereocilia. Since the extracellular Ca2+ concentration will affect the amount of Ca2+ entering during stimulation, it is important to determine the level of the ion close to the sensory cells. Using fluorescence imaging and fluorescence correlation spectroscopy, we measured the Ca2+ concentration near guinea pig stereocilia in situ. Surprisingly, we found that an acellular accessory structure close to the stereocilia, the tectorial membrane, had much higher Ca2+ than the surrounding fluid. Loud sounds depleted Ca2+ from the tectorial membrane, and Ca2+ manipulations had large effects on hair cell function. Hence, the tectorial membrane contributes to control of hearing sensitivity by influencing the ionic environment around the stereocilia.
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46
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Mahfood M, Kamal Eddine Ahmad Mohamed W, Al Mutery A, Tlili A. Clinical Exome Sequencing Identifies a Frameshift Mutation Within the STRC Gene in a United Arab Emirates Family with Profound Nonsyndromic Hearing Loss. Genet Test Mol Biomarkers 2019; 23:204-208. [PMID: 30758234 DOI: 10.1089/gtmb.2018.0264] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIMS Autosomal recessive nonsyndromic hearing loss (ARNSHL) is the most common form of hereditary deafness. Despite its frequency, the diagnosis of this disorder continues to be a challenging task given its extreme genetic heterogeneity. The purpose of this study was to identify the causative mutation in a consanguineous United Arab Emirates (UAE) family with ARNSHL. MATERIALS AND METHODS Clinical exome sequencing (CES) followed by segregation analysis via Sanger sequencing was used to identify the causative mutation. In addition, 109 deaf individuals and 50 deafness-free controls from the UAE population were screened for the identified mutation. RESULTS AND DISCUSSION CES identified the STRC frameshift mutation c.4510del (p.Glu1504Argfs*32) as the causative mutation in this family. Moreover, segregation analysis confirmed the above finding. In addition, the absence of this variant in 109 unrelated deaf individuals and 50 healthy controls indicates that it is rare in the UAE population. CONCLUSION The present study represents the first STRC mutation reported in the UAE population. It also reinforces the power of next-generation sequencing in the diagnosis of heterogenous disorders such as nonsyndromic hearing loss.
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Affiliation(s)
- Mona Mahfood
- 1 Department of Applied Biology, College of Sciences, University of Sharjah, Sharjah, United Arab Emirates
| | | | - Abdullah Al Mutery
- 1 Department of Applied Biology, College of Sciences, University of Sharjah, Sharjah, United Arab Emirates.,2 Molecular Genetics Research Laboratory, University of Sharjah, Sharjah, United Arab Emirates
| | - Abdelaziz Tlili
- 1 Department of Applied Biology, College of Sciences, University of Sharjah, Sharjah, United Arab Emirates.,2 Molecular Genetics Research Laboratory, University of Sharjah, Sharjah, United Arab Emirates.,3 Human Genetics and Stem Cell Laboratory, Research Institute of Sciences and Engineering, University of Sharjah, Sharjah, United Arab Emirates
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47
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Cartagena-Rivera AX, Le Gal S, Richards K, Verpy E, Chadwick RS. Cochlear outer hair cell horizontal top connectors mediate mature stereocilia bundle mechanics. SCIENCE ADVANCES 2019; 5:eaat9934. [PMID: 30801007 PMCID: PMC6382404 DOI: 10.1126/sciadv.aat9934] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 01/10/2019] [Indexed: 05/23/2023]
Abstract
Outer hair cell (OHC) stereocilia bundle deflection opens mechanoelectrical transduction channels at the tips of the stereocilia from the middle and short rows, while bundle cohesion is maintained owing to the presence of horizontal top connectors. Here, we used a quantitative noncontact atomic force microscopy method to investigate stereocilia bundle stiffness and damping, when stimulated at acoustic frequencies and nanometer distances from the bundle. Stereocilia bundle mechanics were determined in stereocilin-deficient mice lacking top connectors and with detached tectorial membrane (Strc -/-/Tecta -/- double knockout) and heterozygous littermate controls (Strc +/-/Tecta -/-). A substantial decrease in bundle stiffness and damping by ~60 and ~74% on postnatal days P13 to P15 was observed when top connectors were absent. Additionally, we followed bundle mechanics during OHC top connectors development between P9 and P15 and quantified the observed increase in OHC bundle stiffness and damping in Strc +/-/Tecta -/- mice while no significant change was detected in Strc -/-/Tecta -/- animals.
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Affiliation(s)
- Alexander X. Cartagena-Rivera
- Section on Auditory Mechanics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sébastien Le Gal
- Unité de Génétique et Physiologie de l’Audition, Institut Pasteur, 75015 Paris, France
- UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), 75015 Paris, France
- Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Complexité du Vivant, 75005 Paris, France
| | - Kerianne Richards
- Genomics and Computational Biology Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Elisabeth Verpy
- Unité de Génétique et Physiologie de l’Audition, Institut Pasteur, 75015 Paris, France
- UMRS 1120, Institut National de la Santé et de la Recherche Médicale (INSERM), 75015 Paris, France
- Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Complexité du Vivant, 75005 Paris, France
| | - Richard S. Chadwick
- Section on Auditory Mechanics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
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Eilertsen M, Valen R, Drivenes Ø, Ebbesson LOE, Helvik JV. Transient photoreception in the hindbrain is permissive to the life history transition of hatching in Atlantic halibut. Dev Biol 2018; 444:129-138. [PMID: 30342886 DOI: 10.1016/j.ydbio.2018.10.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 10/13/2018] [Accepted: 10/15/2018] [Indexed: 12/22/2022]
Abstract
In nonmammalian vertebrates, photoreception takes place in the deep brain already early in development, but knowledge is lacking about the functions of these nonvisual photoreceptive systems. Prior to hatching, Atlantic halibut has a transient bilateral cluster of photoreceptive cells in the hindbrain. The cluster is imbedded in a neuronal network projecting to the narrow belt of hatching glands in the yolk sac. In halibut, hatching is inhibited in light and activated by transfer to darkness and c-fos analysis during hatching shows that the hindbrain cluster and hatching glands have neural activation. Unexpectedly, the hindbrain cluster expresses dual photopigments, vertebrate ancient opsin and melanopsin. Evolutionarily, these opsins are believed to belong to different classes of photopigments found in rhabdomeric and ciliary photoreceptors. The concept that an organism develops transient light sensitivity to target critical aspects of life history transitions as hatching provides a fascinating landscape to investigate the timing of other biological events.
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Affiliation(s)
- Mariann Eilertsen
- Department of Biological Sciences, University of Bergen, N- 5020 Bergen, Norway.
| | - Ragnhild Valen
- Department of Molecular Biology, University of Bergen, N- 5020 Bergen, Norway
| | - Øyvind Drivenes
- Department of Molecular Biology, University of Bergen, N- 5020 Bergen, Norway
| | - Lars O E Ebbesson
- Department of Biological Sciences, University of Bergen, N- 5020 Bergen, Norway; Uni Research AS, Thormøhlensgt. 55, N-5008 Bergen, Norway
| | - Jon Vidar Helvik
- Department of Biological Sciences, University of Bergen, N- 5020 Bergen, Norway
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Abstract
HYPOTHESIS We hypothesized that patients with DFNB16 caused hearing loss show characteristical audiological findings depending on genetic results. BACKGROUND Hearing loss belongs to the most frequent congenital diseases. In 50-70% of individuals, hearing loss is caused by genetic defects. DFNB1 (deafness, neurosensory, autosomal-recessive) is the most frequently affected locus. Despite its great genetic heterogeneity, comprehensive analysis of genes like STRC, encoding stereocilin (DFNB16) is possible. The genetic architecture of the DFNB16 locus is challenging and requires a unique molecular genetic testing assay. The aim of the study is a systematic characterization of the audiological phenotype in DFNB16-positive patients. METHODS Since 2011, 290 patients with suspicion of inherited hearing loss received a human genetic exploration. Eighty two DFNB1-negative patients advanced to further testing in the DFNB16 locus. STRC-positive patients obtained complete audiological diagnostic workup. Additionally, epidemiological data was collected. RESULTS Nine of 82 (11%) of the examined patients (mean age 5 yr) showed mutations in the STRC (3 homozygous, 6 compound heterozygous). Aside from a moderate hearing loss in the pure tone audiogram, auditory brainstem response thresholds were 40-50 dB nHL. Otoacoustic emissions were detectable in only one patient. CONCLUSIONS Examination of the DFNB16-locus should be a standard diagnostic test after negative DFNB1-gene screening result. Notably, DFNB16-associated hearing loss can be audiologically characterized as moderate sensorineural hearing loss in the main speech field with absent otoacoustic emissions. Our study is the first to correlate audiological findings with genetic results in patients with hearing loss due to STRC.
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Stereocilin gene variants associated with episodic vertigo: expansion of the DFNB16 phenotype. Eur J Hum Genet 2018; 26:1871-1874. [PMID: 30250054 DOI: 10.1038/s41431-018-0256-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 08/07/2018] [Accepted: 08/19/2018] [Indexed: 11/08/2022] Open
Abstract
Vestibular disorders comprise a heterogeneous group of diseases with transient or permanent loss of vestibular function. Vestibulopathy is in most cases associated with migraine, Ménière disease, hereditary ataxias, or sensorineural hearing loss. We identified two brothers and their first cousin affected by hearing loss and episodic vertigo. The brothers were homozygous STRC nonsense variant [c.4027 C > T, p.(Q1343*)], whereas their first cousin was compound heterozygous for the STRC nonsense variant and a 97 kb deletion spanning the entire STRC gene. Clinical investigations confirmed pathological vestibular responses in addition to a characteristic DFNB16 hearing loss. The STRC gene encodes Stereocilin in the cochlea and in the vestibular organ where it ensheathes the kinocilium of the otolithic membranes. Stereocilin is associated with the gel overlaying the vestibular kinocilia, suggesting a role for the protein in sensing balance and spatial orientation. Our findings support such a function for Stereocilin in the vestibular organ and expand the phenotype associated with DFNB16.
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