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Kaur N, Arora K, Radhakrishnan P, Narayanan DL, Shukla A. Intragenic homozygous duplication in HEPACAM is associated with megalencephalic leukoencephalopathy with subcortical cysts type 2A. Neurogenetics 2024; 25:85-91. [PMID: 38280046 DOI: 10.1007/s10048-024-00743-1] [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: 10/16/2023] [Accepted: 01/05/2024] [Indexed: 01/29/2024]
Abstract
Disease-causing variants in HEPACAM are associated with megalencephalic leukoencephalopathy with subcortical cysts 2A (MLC2A, MIM# 613,925, autosomal recessive), and megalencephalic leukoencephalopathy with subcortical cysts 2B, remitting, with or without impaired intellectual development (MLC2B, MIM# 613,926, autosomal dominant). These disorders are characterised by macrocephaly, seizures, motor delay, cognitive impairment, ataxia, and spasticity. Brain magnetic resonance imaging (MRI) in these individuals shows swollen cerebral hemispheric white matter and subcortical cysts, mainly in the frontal and temporal regions. To date, 45 individuals from 39 families are reported with biallelic and heterozygous variants in HEPACAM, causing MLC2A and MLC2B, respectively. A 9-year-old male presented with developmental delay, gait abnormalities, seizures, macrocephaly, dysarthria, spasticity, and hyperreflexia. MRI revealed subcortical cysts with diffuse cerebral white matter involvement. Whole-exome sequencing (WES) in the proband did not reveal any clinically relevant single nucleotide variants. However, copy number variation analysis from the WES data of the proband revealed a copy number of 4 for exons 3 and 4 of HEPACAM. Validation and segregation were done by quantitative PCR which confirmed the homozygous duplication of these exons in the proband and carrier status in both parents. To the best of our knowledge, this is the first report of an intragenic duplication in HEPACAM causing MLC2A.
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Affiliation(s)
- Namanpreet Kaur
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Khyati Arora
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Periyasamy Radhakrishnan
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Dhanya Lakshmi Narayanan
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
- DBT-Wellcome Trust India Alliance Early Career Clinical and Public Health Research Fellow, Hyderabad, India
| | - Anju Shukla
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India.
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2
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Herb M. NADPH Oxidase 3: Beyond the Inner Ear. Antioxidants (Basel) 2024; 13:219. [PMID: 38397817 PMCID: PMC10886416 DOI: 10.3390/antiox13020219] [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: 01/13/2024] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 02/25/2024] Open
Abstract
Reactive oxygen species (ROS) were formerly known as mere byproducts of metabolism with damaging effects on cellular structures. The discovery and description of NADPH oxidases (Nox) as a whole enzyme family that only produce this harmful group of molecules was surprising. After intensive research, seven Nox isoforms were discovered, described and extensively studied. Among them, the NADPH oxidase 3 is the perhaps most underrated Nox isoform, since it was firstly discovered in the inner ear. This stigma of Nox3 as "being only expressed in the inner ear" was also used by me several times. Therefore, the question arose whether this sentence is still valid or even usable. To this end, this review solely focuses on Nox3 and summarizes its discovery, the structural components, the activating and regulating factors, the expression in cells, tissues and organs, as well as the beneficial and detrimental effects of Nox3-mediated ROS production on body functions. Furthermore, the involvement of Nox3-derived ROS in diseases progression and, accordingly, as a potential target for disease treatment, will be discussed.
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Affiliation(s)
- Marc Herb
- Institute for Medical Microbiology, Immunology and Hygiene, Faculty of Medicine, University Hospital Cologne, University of Cologne, 50935 Cologne, Germany;
- German Centre for Infection Research, Partner Site Bonn-Cologne, 50931 Cologne, Germany
- Cologne Cluster of Excellence on Cellular Stress Responses in Aging-Associated Diseases (CECAD), 50931 Cologne, Germany
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3
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Pressé MT, Malgrange B, Delacroix L. The cochlear matrisome: Importance in hearing and deafness. Matrix Biol 2024; 125:40-58. [PMID: 38070832 DOI: 10.1016/j.matbio.2023.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/20/2023] [Accepted: 12/06/2023] [Indexed: 02/12/2024]
Abstract
The extracellular matrix (ECM) consists in a complex meshwork of collagens, glycoproteins, and proteoglycans, which serves a scaffolding function and provides viscoelastic properties to the tissues. ECM acts as a biomechanical support, and actively participates in cell signaling to induce tissular changes in response to environmental forces and soluble cues. Given the remarkable complexity of the inner ear architecture, its exquisite structure-function relationship, and the importance of vibration-induced stimulation of its sensory cells, ECM is instrumental to hearing. Many factors of the matrisome are involved in cochlea development, function and maintenance, as evidenced by the variety of ECM proteins associated with hereditary deafness. This review describes the structural and functional ECM components in the auditory organ and how they are modulated over time and following injury.
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Affiliation(s)
- Mary T Pressé
- Developmental Neurobiology Unit, GIGA-Neurosciences, University of Liège, 15 avenue Hippocrate - CHU - B36 (1st floor), Liège B-4000, Belgium
| | - Brigitte Malgrange
- Developmental Neurobiology Unit, GIGA-Neurosciences, University of Liège, 15 avenue Hippocrate - CHU - B36 (1st floor), Liège B-4000, Belgium
| | - Laurence Delacroix
- Developmental Neurobiology Unit, GIGA-Neurosciences, University of Liège, 15 avenue Hippocrate - CHU - B36 (1st floor), Liège B-4000, Belgium.
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4
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Yang HW, Lee S, Berry BC, Yang D, Zheng S, Carroll RS, Park PJ, Johnson MD. A role for mutations in AK9 and other genes affecting ependymal cells in idiopathic normal pressure hydrocephalus. Proc Natl Acad Sci U S A 2023; 120:e2300681120. [PMID: 38100419 PMCID: PMC10743366 DOI: 10.1073/pnas.2300681120] [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: 01/12/2023] [Accepted: 11/06/2023] [Indexed: 12/17/2023] Open
Abstract
Idiopathic normal pressure hydrocephalus (iNPH) is an enigmatic neurological disorder that develops after age 60 and is characterized by gait difficulty, dementia, and incontinence. Recently, we reported that heterozygous CWH43 deletions may cause iNPH. Here, we identify mutations affecting nine additional genes (AK9, RXFP2, PRKD1, HAVCR1, OTOG, MYO7A, NOTCH1, SPG11, and MYH13) that are statistically enriched among iNPH patients. The encoded proteins are all highly expressed in choroid plexus and ependymal cells, and most have been associated with cilia. Damaging mutations in AK9, which encodes an adenylate kinase, were detected in 9.6% of iNPH patients. Mice homozygous for an iNPH-associated AK9 mutation displayed normal cilia structure and number, but decreased cilia motility and beat frequency, communicating hydrocephalus, and balance impairment. AK9+/- mice displayed normal brain development and behavior until early adulthood, but subsequently developed communicating hydrocephalus. Together, our findings suggest that heterozygous mutations that impair ventricular epithelial function may contribute to iNPH.
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Affiliation(s)
- Hong Wei Yang
- Department of Neurological Surgery, University of Massachusetts Chan Medical School, Worcester, MA01655
| | - Semin Lee
- Brigham and Women’s Hospital, Boston, MA02115
- Harvard Medical School, Boston, MA02115
| | - Bethany C. Berry
- Department of Neurological Surgery, University of Massachusetts Chan Medical School, Worcester, MA01655
| | - Dejun Yang
- Department of Neurological Surgery, University of Massachusetts Chan Medical School, Worcester, MA01655
| | - Shaokuan Zheng
- Department of Neurological Surgery, University of Massachusetts Chan Medical School, Worcester, MA01655
| | - Rona S. Carroll
- Department of Neurological Surgery, University of Massachusetts Chan Medical School, Worcester, MA01655
- Brigham and Women’s Hospital, Boston, MA02115
- Harvard Medical School, Boston, MA02115
| | - Peter J. Park
- Brigham and Women’s Hospital, Boston, MA02115
- Harvard Medical School, Boston, MA02115
| | - Mark D. Johnson
- Department of Neurological Surgery, University of Massachusetts Chan Medical School, Worcester, MA01655
- Department of Neurological Surgery, University of Massachusetts Memorial Health, Worcester, MA01655
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5
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Steinhart MR, van der Valk WH, Osorio D, Serdy SA, Zhang J, Nist-Lund C, Kim J, Moncada-Reid C, Sun L, Lee J, Koehler KR. Mapping oto-pharyngeal development in a human inner ear organoid model. Development 2023; 150:dev201871. [PMID: 37796037 DOI: 10.1242/dev.201871] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 09/08/2023] [Indexed: 10/06/2023]
Abstract
Inner ear development requires the coordination of cell types from distinct epithelial, mesenchymal and neuronal lineages. Although we have learned much from animal models, many details about human inner ear development remain elusive. We recently developed an in vitro model of human inner ear organogenesis using pluripotent stem cells in a 3D culture, fostering the growth of a sensorineural circuit, including hair cells and neurons. Despite previously characterizing some cell types, many remain undefined. This study aimed to chart the in vitro development timeline of the inner ear organoid to understand the mechanisms at play. Using single-cell RNA sequencing at ten stages during the first 36 days of differentiation, we tracked the evolution from pluripotency to various ear cell types after exposure to specific signaling modulators. Our findings showcase gene expression that influences differentiation, identifying a plethora of ectodermal and mesenchymal cell types. We also discern aspects of the organoid model consistent with in vivo development, while highlighting potential discrepancies. Our study establishes the Inner Ear Organoid Developmental Atlas (IODA), offering deeper insights into human biology and improving inner ear tissue differentiation.
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Affiliation(s)
- Matthew R Steinhart
- Department of Otolaryngology, Boston Children's Hospital, Boston, MA 02115, USA
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Medical Neuroscience Graduate Program, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Wouter H van der Valk
- Department of Otolaryngology, Boston Children's Hospital, Boston, MA 02115, USA
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
- Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA 02115, USA
- OtoBiology Leiden, Department of Otorhinolaryngology and Head & Neck Surgery; Leiden University Medical Center, Leiden 2333 ZA, the Netherlands
- The Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW); Leiden University Medical Center, Leiden, 2333 ZA, the Netherlands
| | - Daniel Osorio
- Research Computing, Department of Information Technology; Boston Children's Hospital, Boston, MA 02115, USA
| | - Sara A Serdy
- Department of Otolaryngology, Boston Children's Hospital, Boston, MA 02115, USA
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Jingyuan Zhang
- Department of Otolaryngology, Boston Children's Hospital, Boston, MA 02115, USA
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
- Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA 02115, USA
| | - Carl Nist-Lund
- Department of Otolaryngology, Boston Children's Hospital, Boston, MA 02115, USA
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
- Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - Jin Kim
- Department of Otolaryngology, Boston Children's Hospital, Boston, MA 02115, USA
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
- Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA 02115, USA
- Department of Plastic and Oral Surgery, Boston Children's Hospital, Boston, MA 02115, USA
| | - Cynthia Moncada-Reid
- Speech and Hearing Bioscience and Technology (SHBT) Graduate Program, Harvard Medical School, Boston, MA 02115, USA
| | - Liang Sun
- Research Computing, Department of Information Technology; Boston Children's Hospital, Boston, MA 02115, USA
| | - Jiyoon Lee
- Department of Otolaryngology, Boston Children's Hospital, Boston, MA 02115, USA
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
- Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA 02115, USA
- Department of Plastic and Oral Surgery, Boston Children's Hospital, Boston, MA 02115, USA
| | - Karl R Koehler
- Department of Otolaryngology, Boston Children's Hospital, Boston, MA 02115, USA
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
- Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Boston, MA 02115, USA
- Department of Plastic and Oral Surgery, Boston Children's Hospital, Boston, MA 02115, USA
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Senofsky N, Faber J, Bozovic D. Vestibular Drop Attacks and Meniere's Disease as Results of Otolithic Membrane Damage-A Numerical Model. J Assoc Res Otolaryngol 2023; 24:107-115. [PMID: 36517730 PMCID: PMC9971529 DOI: 10.1007/s10162-022-00880-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Accepted: 11/20/2022] [Indexed: 12/15/2022] Open
Abstract
Meniere's disease (MD) is a condition of the inner ear with symptoms affecting both vestibular and hearing functions. Some patients with MD experience vestibular drop attacks (VDAs), which are violent falls caused by spurious vestibular signals from the utricle and/or saccule. Recent surgical work has shown that patients who experience VDAs also show disrupted utricular otolithic membranes. The objective of this study is to determine if otolithic membrane damage alone is sufficient to induce spurious vestibular signals, thus potentially eliciting VDAs and the vestibular dysfunction seen in patients with MD. We use a previously developed numerical model to describe the nonlinear dynamics of an array of active, elastically coupled hair cells. We then reduce the coupling strength of a selected region of the membrane to model the effects of tissue damage. As we reduce the coupling strength, we observe large and abrupt spikes in hair bundle position. As bundle displacements from the equilibrium position have been shown to lead to depolarization of the hair-cell soma and hence trigger neural activity, this spontaneous activity could elicit false detection of a vestibular signal. The results of this numerical model suggest that otolithic membrane damage alone may be sufficient to induce VDAs and the vestibular dysfunction seen in patients with MD. Future experimental work is needed to confirm these results in vitro.
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Affiliation(s)
- Nicholas Senofsky
- Department of Physics and Astronomy, Physics and Astronomy Building, University of California, 430 Portola Pl, Los Angeles, CA, USA.
| | - Justin Faber
- grid.19006.3e0000 0000 9632 6718Department of Physics and Astronomy, Physics and Astronomy Building, University of California, 430 Portola Pl, Los Angeles, CA USA
| | - Dolores Bozovic
- grid.19006.3e0000 0000 9632 6718Department of Physics and Astronomy, Physics and Astronomy Building, University of California, 430 Portola Pl, Los Angeles, CA USA ,grid.509979.b0000 0004 7666 6191California NanoSystems Institute, University of California, Los Angeles, CA 90095 USA
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7
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Ortner NJ. CACNA1D-Related Channelopathies: From Hypertension to Autism. Handb Exp Pharmacol 2023. [PMID: 36592224 DOI: 10.1007/164_2022_626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Tightly controlled Ca2+ influx through voltage-gated Ca2+ channels (Cavs) is indispensable for proper physiological function. Thus, it is not surprising that Cav loss and/or gain of function have been implicated in human pathology. Deficiency of Cav1.3 L-type Ca2+ channels (LTCCs) causes deafness and bradycardia, whereas several genetic variants of CACNA1D, the gene encoding the pore-forming α1 subunit of Cav1.3, have been linked to various disease phenotypes, such as hypertension, congenital hypoglycemia, or autism. These variants include not only common polymorphisms associated with an increased disease risk, but also rare de novo missense variants conferring high risk. This review provides a concise summary of disease-associated CACNA1D variants, whereas the main focus lies on de novo germline variants found in individuals with a neurodevelopmental disorder of variable severity. Electrophysiological recordings revealed activity-enhancing gating changes induced by these de novo variants, and tools to predict their pathogenicity and to study the resulting pathophysiological consequences will be discussed. Despite the low number of affected patients, potential phenotype-genotype correlations and factors that could impact the severity of symptoms will be covered. Since increased channel activity is assumed as the disease-underlying mechanism, pharmacological inhibition could be a treatment option. In the absence of Cav1.3-selective blockers, dihydropyridine LTCC inhibitors clinically approved for the treatment of hypertension may be used for personalized off-label trials. Findings from in vitro studies and treatment attempts in some of the patients seem promising as outlined. Taken together, due to advances in diagnostic sequencing techniques the number of reported CACNA1D variants in human diseases is constantly rising. Evidence from in silico, in vitro, and in vivo disease models can help to predict the pathogenic potential of such variants and to guide diagnosis and treatment in the clinical practice when confronted with patients harboring CACNA1D variants.
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Affiliation(s)
- Nadine J Ortner
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria.
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Hui J, Lei Q, Ji Z, Zi D. Betahistine alleviates benign paroxysmal positional vertigo (BPPV) through inducing production of multiple CTRP family members and activating the ERK1/2-AKT/PPARy pathway. Biol Res 2022; 55:16. [PMID: 35379352 PMCID: PMC8981858 DOI: 10.1186/s40659-022-00385-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 03/21/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Betahistine is a clinical medication for the treatment of benign paroxysmal positional vertigo (BPPV). Otolin, a secreted glycoprotein with a C-terminal globular domain homologous to the immune complement C1q, has been identified as a biomarker for BPPV. However, the role of complement C1q/TNF-related proteins (CTRPs) with a C-terminal globular domain in BPPV is unclear, so we explored the change of CTRPs in betahistine treated BPPV. METHODS We treated BPPV patients with Betahistine (12 mg/time, 3 times/day) for 4 weeks and observed the clinical efficacy and the expression of CTRP family members in BPPV patients. Then, we constructed a vertigo mice model of vestibular dysfunction with gentamicin (150 mg/Kg) and a BPPV model of Slc26a4loop/loop mutant mice. Adenoviral vectors for CTRP expression vector and small interfering RNA were injected via the intratympanic injection into mice and detected the expression of CTRP family members, phosphorylation levels of ERK and AKT and the expression of PPARγ. In addition, we treated mice of vestibular dysfunction with Betahistine (10 mg/Kg) and/or ERK inhibitor of SCH772984 (12 mg/Kg) and/or and PPARγ antagonist GW9662 (1 mg/Kg) for 15 days, and evaluated the accuracy of air righting reflex, the time of contact righting reflex and the scores of head tilt and swimming behavior. RESULTS After treatment with Betahistine, the residual dizziness duration and the score of the evaluation were reduced, and the expression of CTRP1, 3, 6, 9 and 12 were significantly increased in BPPV patients. We also found that Betahistine improved the accuracy of air righting reflex, reduced the time of contact righting reflex and the scores of head tilt and swimming behavior in gentamicin-treated mice and Slc26a4loop/loop mutant mice. The expression levels of CTRP1, 3, 6, 9 and 12, phosphorylation levels of ERK and AKT, and PPARγ expression were significantly increased, and the scores of head tilt and swimming behavior were decreased in vestibular dysfunction mice with overexpression of CTRPs. Silencing CTRPs has the opposite effect. SCH772984 reversed the effect of Betahistine in mice with vestibular dysfunction. CONCLUSION Betahistine alleviates BPPV through inducing production of multiple CTRP family members and activating the ERK1/2-AKT/PPARy pathway.
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Affiliation(s)
- Jing Hui
- Department of Neurology, The Second Affiliated Hospital of Xi'an Medical College, Xi'an, 710038, China
| | - Qi Lei
- Shaanxi Normal University Hospital, Xi'an, 710119, China
| | - Zhi Ji
- Department of Neurology, The Second Affiliated Hospital of Xi'an Medical College, Xi'an, 710038, China
| | - Dingjing Zi
- Department of Otolaryngology, The Second Affiliated Hospital of Air Force Medical University, No. 1 Xinsi Road, Xi'an , 710038, China.
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Maudoux A, Vitry S, El-Amraoui A. Vestibular Deficits in Deafness: Clinical Presentation, Animal Modeling, and Treatment Solutions. Front Neurol 2022; 13:816534. [PMID: 35444606 PMCID: PMC9013928 DOI: 10.3389/fneur.2022.816534] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 02/23/2022] [Indexed: 11/13/2022] Open
Abstract
The inner ear is responsible for both hearing and balance. These functions are dependent on the correct functioning of mechanosensitive hair cells, which convert sound- and motion-induced stimuli into electrical signals conveyed to the brain. During evolution of the inner ear, the major changes occurred in the hearing organ, whereas the structure of the vestibular organs remained constant in all vertebrates over the same period. Vestibular deficits are highly prevalent in humans, due to multiple intersecting causes: genetics, environmental factors, ototoxic drugs, infections and aging. Studies of deafness genes associated with balance deficits and their corresponding animal models have shed light on the development and function of these two sensory systems. Bilateral vestibular deficits often impair individual postural control, gaze stabilization, locomotion and spatial orientation. The resulting dizziness, vertigo, and/or falls (frequent in elderly populations) greatly affect patient quality of life. In the absence of treatment, prosthetic devices, such as vestibular implants, providing information about the direction, amplitude and velocity of body movements, are being developed and have given promising results in animal models and humans. Novel methods and techniques have led to major progress in gene therapies targeting the inner ear (gene supplementation and gene editing), 3D inner ear organoids and reprograming protocols for generating hair cell-like cells. These rapid advances in multiscale approaches covering basic research, clinical diagnostics and therapies are fostering interdisciplinary research to develop personalized treatments for vestibular disorders.
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Affiliation(s)
- Audrey Maudoux
- Unit Progressive Sensory Disorders, Pathophysiology and Therapy, Institut Pasteur, Institut de l'Audition, Université de Paris, INSERM-UMRS1120, Paris, France
- Center for Balance Evaluation in Children (EFEE), Otolaryngology Department, Assistance Publique des Hôpitaux de Paris, Robert-Debré University Hospital, Paris, France
| | - Sandrine Vitry
- Unit Progressive Sensory Disorders, Pathophysiology and Therapy, Institut Pasteur, Institut de l'Audition, Université de Paris, INSERM-UMRS1120, Paris, France
| | - Aziz El-Amraoui
- Unit Progressive Sensory Disorders, Pathophysiology and Therapy, Institut Pasteur, Institut de l'Audition, Université de Paris, INSERM-UMRS1120, Paris, France
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10
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Pan C, Li J, Wang S, Shi C, Zhang Y, Yu Y. Novel heterozygous mutations in the otogelin-like (OTOGL) gene in a child with bilateral mild nonsyndromic sensorineural hearing loss. Gene 2022; 808:146000. [PMID: 34626719 DOI: 10.1016/j.gene.2021.146000] [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: 08/22/2021] [Revised: 09/22/2021] [Accepted: 10/04/2021] [Indexed: 11/29/2022]
Abstract
Hearing loss is a common disease, of which genetic factors are the main cause. The incidence of mild or moderate postlingual deafness in children is not high, and the impact on life and learning is not as severe as that of prelingual deafness. This leads to insufficient attention to the disorder in the clinic. To date, only a few disease-causing genes have been reported. This report describe a case of novel heterozygous mutations in OTOGL that causes nonsyndromic mild sensorineural hearing loss. Basic information, imaging examinations, audiological examination, and vestibular function tests of the proband were collected. Blood samples of the proband's family were collected and analyzed by whole exome sequencing and Sanger sequencing. A pedigree diagram was drawn and the genetic patterns were analyzed. The proband is a 16-year-old female student with mild sensorineural hearing loss. High-resolution CT of the inner ear and vestibular function tests showed no abnormalities. The age of onset was approximately 4 years old. Except for hearing loss, no lesions were seen in other organs. The parents of the proband were not close relatives and had normal hearing. Two novel heterozygous mutations were found in the OTOGL gene. The c.5038del (p.D1680Ifs*6) variant was inherited from the father, and the c.2770C > T (p.R924X) variant from the mother. They enriched the mutation spectrum of OTOGL, which provides the basis for gene function research and genetic consultation.
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Affiliation(s)
- Chen Pan
- Department of Otolaryngology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Jun Li
- Department of Otolaryngology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Shixin Wang
- Department of Otolaryngology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Chen Shi
- Department of Otolaryngology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Yunmei Zhang
- Department of Otolaryngology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Yafeng Yu
- Department of Otolaryngology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China.
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11
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Skuladottir AT, Bjornsdottir G, Nawaz MS, Petersen H, Rognvaldsson S, Moore KHS, Olafsson PI, Magnusson SH, Bjornsdottir A, Sveinsson OA, Sigurdardottir GR, Saevarsdottir S, Ivarsdottir EV, Stefansdottir L, Gunnarsson B, Muhlestein JB, Knowlton KU, Jones DA, Nadauld LD, Hartmann AM, Rujescu D, Strupp M, Walters GB, Thorgeirsson TE, Jonsdottir I, Holm H, Thorleifsson G, Gudbjartsson DF, Sulem P, Stefansson H, Stefansson K. A genome-wide meta-analysis uncovers six sequence variants conferring risk of vertigo. Commun Biol 2021; 4:1148. [PMID: 34620984 PMCID: PMC8497462 DOI: 10.1038/s42003-021-02673-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 09/09/2021] [Indexed: 11/17/2022] Open
Abstract
Vertigo is the leading symptom of vestibular disorders and a major risk factor for falls. In a genome-wide association study of vertigo (Ncases = 48,072, Ncontrols = 894,541), we uncovered an association with six common sequence variants in individuals of European ancestry, including missense variants in ZNF91, OTOG, OTOGL, and TECTA, and a cis-eQTL for ARMC9. The association of variants in ZNF91, OTOGL, and OTOP1 was driven by an association with benign paroxysmal positional vertigo. Using previous reports of sequence variants associating with age-related hearing impairment and motion sickness, we found eight additional variants that associate with vertigo. Although disorders of the auditory and the vestibular system may co-occur, none of the six genome-wide significant vertigo variants were associated with hearing loss and only one was associated with age-related hearing impairment. Our results uncovered sequence variants associating with vertigo in a genome-wide association study and implicated genes with known roles in inner ear development, maintenance, and disease.
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Affiliation(s)
| | | | - Muhammad Sulaman Nawaz
- deCODE genetics/Amgen Inc., Reykjavik, Iceland
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland
| | - Hannes Petersen
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland
- Akureyri Hospital, Akureyri, Iceland
| | | | | | | | | | | | - Olafur A Sveinsson
- Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland
| | | | - Saedis Saevarsdottir
- deCODE genetics/Amgen Inc., Reykjavik, Iceland
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland
- Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland
| | | | | | | | - Joseph B Muhlestein
- Intermountain Medical Center, Intermountain Heart Institute, Salt Lake City, UT, USA
- University of Utah, School of Medicine, Salt Lake City, UT, USA
| | - Kirk U Knowlton
- Intermountain Medical Center, Intermountain Heart Institute, Salt Lake City, UT, USA
- University of Utah, School of Medicine, Salt Lake City, UT, USA
| | - David A Jones
- Precision Genomics, Intermountain Healthcare, Saint George, UT, USA
| | - Lincoln D Nadauld
- Precision Genomics, Intermountain Healthcare, Saint George, UT, USA
- Stanford University, School of Medicine, Stanford, CA, USA
| | - Annette M Hartmann
- Department of Psychiatry, Psychotherapy and Psychosomatics, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Dan Rujescu
- Department of Psychiatry, Psychotherapy and Psychosomatics, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Michael Strupp
- Department of Neurology and German Center for Vertigo and Balance Disorders, Ludwig Maximilians University, Munich, Germany
| | - G Bragi Walters
- deCODE genetics/Amgen Inc., Reykjavik, Iceland
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland
| | | | - Ingileif Jonsdottir
- deCODE genetics/Amgen Inc., Reykjavik, Iceland
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland
| | - Hilma Holm
- deCODE genetics/Amgen Inc., Reykjavik, Iceland
| | | | | | | | | | - Kari Stefansson
- deCODE genetics/Amgen Inc., Reykjavik, Iceland.
- Faculty of Medicine, University of Iceland, Reykjavik, Iceland.
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12
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Song P, Zhao X, Xu Y, Zhao Z, Liu Y, Gao Q. Morphological Effect of Vitamin D Deficiency on Globular Substances in Mice. Otol Neurotol 2021; 42:e1313-e1317. [PMID: 34121084 DOI: 10.1097/mao.0000000000003229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
OBJECTIVE Many authors, including us, elucidated that vitamin D deficiency was a risk factor for benign paroxysmal position vertigo. We speculated vitamin D deficiency was likely to intervene otoconia formation by globular substance (GS). METHODS Kunming mice were randomly divided into three groups: vitamin D sufficient group (12-wk standard control diet), vitamin D deficiency group (16-wk vitamin D deficiency diet), and vitamin D supplement group (16-wk vitamin D deficiency diet and followed 8-wk standard control diet). At 12, 16, and 24 weeks, blood was collected for measuring vitamin D and macula utriculi were obtained for research under scanning electron microscope (SEM). We randomly selected 10 SEM photographs of macula utriculi in each mouse, counted cilium and GS, and measured diameters of counted GS. The ratio of the number of GS to cilium in each SEM photograph was defined as density of GS. RESULTS The diameter and density of GS were larger and higher in vitamin D deficiency group than sufficient group (p < 0.05; p < 0.05). There was no significant difference in density and diameters of GS between vitamin D deficiency and supplement group. The rough and grainy surface became smoother and smoother along with vitamin D deficiency, and reappeared after vitamin D supplement for 8 weeks. CONCLUSION GS secreted as a precursor of mature otoconia is affected by vitamin D deficiency and vitamin D supplementation can mitigate the effects in mice. The density of GS, a quantitative method we designed, can quantify GS well.
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Affiliation(s)
- Penglong Song
- Department of Otolaryngology/Head and Neck Surgery, The First Affiliated Hospital, Harbin Medical University
| | - Xianshu Zhao
- Health Center of Screening and Prevention of Diseases, The First Affiliated Hospital, Harbin Medical University, Harbin, China
| | - Yanjun Xu
- Department of Otolaryngology/Head and Neck Surgery, The First Affiliated Hospital, Harbin Medical University
| | - Zhigang Zhao
- Department of Otolaryngology/Head and Neck Surgery, The First Affiliated Hospital, Harbin Medical University
| | - Yang Liu
- Department of Otolaryngology/Head and Neck Surgery, The First Affiliated Hospital, Harbin Medical University
| | - Qian Gao
- Department of Otolaryngology/Head and Neck Surgery, The First Affiliated Hospital, Harbin Medical University
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Peusner KD, Bell NM, Hirsch JC, Beraneck M, Popratiloff A. Understanding the Pathophysiology of Congenital Vestibular Disorders: Current Challenges and Future Directions. Front Neurol 2021; 12:708395. [PMID: 34589045 PMCID: PMC8475631 DOI: 10.3389/fneur.2021.708395] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 08/13/2021] [Indexed: 12/13/2022] Open
Abstract
In congenital vestibular disorders (CVDs), children develop an abnormal inner ear before birth and face postnatal challenges to maintain posture, balance, walking, eye-hand coordination, eye tracking, or reading. Only limited information on inner ear pathology is acquired from clinical imaging of the temporal bone or studying histological slides of the temporal bone. A more comprehensive and precise assessment and determination of the underlying mechanisms necessitate analyses of the disorders at the cellular level, which can be achieved using animal models. Two main criteria for a suitable animal model are first, a pathology that mirrors the human disorder, and second, a reproducible experimental outcome leading to statistical power. With over 40 genes that affect inner ear development, the phenotypic abnormalities resulting from congenital vestibular disorders (CVDs) are highly variable. Nonetheless, there is a large subset of CVDs that form a common phenotype of a sac-like inner ear with the semicircular canals missing or dysplastic, and discrete abnormalities in the vestibular sensory organs. We have focused the review on this subset, but to advance research on CVDs we have added other CVDs not forming a sac-like inner ear. We have included examples of animal models used to study these CVDs. Presently, little is known about the central pathology resulting from CVDs at the cellular level in the central vestibular neural network, except for preliminary studies on a chick model that show significant loss of second-order, vestibular reflex projection neurons.
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Affiliation(s)
- Kenna D Peusner
- Department of Neurology, The George Washington University School of Medicine and Health Sciences, Washington, DC, United States
| | - Nina M Bell
- Department of Neurology, The George Washington University School of Medicine and Health Sciences, Washington, DC, United States
| | - June C Hirsch
- Department of Neurology, The George Washington University School of Medicine and Health Sciences, Washington, DC, United States
| | - Mathieu Beraneck
- Université de Paris, Integrative Neuroscience and Cognition Center, CNRS UMR 8002, Paris, France
| | - Anastas Popratiloff
- The George Washington University Nanofabrication and Imaging Center, Washington, DC, United States
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14
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Mackowetzky K, Yoon KH, Mackowetzky EJ, Waskiewicz AJ. Development and evolution of the vestibular apparatuses of the inner ear. J Anat 2021; 239:801-828. [PMID: 34047378 PMCID: PMC8450482 DOI: 10.1111/joa.13459] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 04/07/2021] [Accepted: 05/06/2021] [Indexed: 12/16/2022] Open
Abstract
The vertebrate inner ear is a labyrinthine sensory organ responsible for perceiving sound and body motion. While a great deal of research has been invested in understanding the auditory system, a growing body of work has begun to delineate the complex developmental program behind the apparatuses of the inner ear involved with vestibular function. These animal studies have helped identify genes involved in inner ear development and model syndromes known to include vestibular dysfunction, paving the way for generating treatments for people suffering from these disorders. This review will provide an overview of known inner ear anatomy and function and summarize the exciting discoveries behind inner ear development and the evolution of its vestibular apparatuses.
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Affiliation(s)
- Kacey Mackowetzky
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - Kevin H. Yoon
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | | | - Andrew J. Waskiewicz
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
- Women & Children’s Health Research InstituteUniversity of AlbertaEdmontonAlbertaCanada
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15
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Cruz Marino T, Tardif J, Leblanc J, Lavoie J, Morin P, Harvey M, Thomas MJ, Pratte A, Braverman N. First glance at the molecular etiology of hearing loss in French-Canadian families from Saguenay-Lac-Saint-Jean's founder population. Hum Genet 2021; 141:607-622. [PMID: 34387732 DOI: 10.1007/s00439-021-02332-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 08/04/2021] [Indexed: 11/24/2022]
Abstract
The French-Canadian population of Saguenay-Lac-Saint-Jean is known for its homogenous genetic background. The hereditary causes of hearing loss were previously unexplored in this population. Individuals with hearing loss were referred from the otorhinolaryngology, pediatrics and family physicians' clinics to the medical genetics service at the Centre intégré universitaire de santé et de services sociaux du Saguenay-Lac-Saint-Jean between June 2015 and March 2021. A regional clinical evaluation strategy was developed. Samples from 63 individuals belonging to 41 families were sent independently to different molecular clinical laboratories and index cases were analyzed through comprehensive multigene panels, with a diagnostic rate of 54%. Sixteen hearing loss causal variants were identified in 12 genes, with eight of these variants not been previously reported in the literature. Recurrent variants were present in four genes, suggesting a possible founder effect, while GJB2 gene variants were scarce. A comprehensive multigene panel approach as part of the proposed clinical evaluation strategy offers a high diagnostic yield for this population.
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Affiliation(s)
- Tania Cruz Marino
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Saguenay-Lac-Saint-Jean, Canada.
| | - Jessica Tardif
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Saguenay-Lac-Saint-Jean, Canada
| | - Josianne Leblanc
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Saguenay-Lac-Saint-Jean, Canada
| | - Janie Lavoie
- Department of Otolaryngology-Head and Neck Surgery, CIUSSS Saguenay-Lac-St-Jean, Saguenay-Lac-Saint-Jean, Canada
| | - Pascal Morin
- Department of Otolaryngology-Head and Neck Surgery, CIUSSS Saguenay-Lac-St-Jean, Saguenay-Lac-Saint-Jean, Canada
| | - Michel Harvey
- Department of Otolaryngology-Head and Neck Surgery, CIUSSS Saguenay-Lac-St-Jean, Saguenay-Lac-Saint-Jean, Canada
| | - Marie-Jacqueline Thomas
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Saguenay-Lac-Saint-Jean, Canada
| | - Annabelle Pratte
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Saguenay-Lac-Saint-Jean, Canada
| | - Nancy Braverman
- Division of Medical Genetics, Department of Pediatrics and Human Genetics, McGill University, Montreal, Canada
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Roman-Naranjo P, Gallego-Martinez A, Soto-Varela A, Aran I, Moleon MDC, Espinosa-Sanchez JM, Amor-Dorado JC, Batuecas-Caletrio A, Perez-Vazquez P, Lopez-Escamez JA. Burden of Rare Variants in the OTOG Gene in Familial Meniere's Disease. Ear Hear 2021; 41:1598-1605. [PMID: 33136635 DOI: 10.1097/aud.0000000000000878] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
OBJECTIVES Meniere's disease (MD) is a rare inner ear disorder characterized by sensorineural hearing loss, episodic vertigo, and tinnitus. Familial MD has been reported in 6 to 9% of sporadic cases, and few genes including FAM136A, DTNA, PRKCB, SEMA3D, and DPT have been involved in single families, suggesting genetic heterogeneity. In this study, the authors recruited 46 families with MD to search for relevant candidate genes for hearing loss in familial MD. DESIGN Exome sequencing data from MD patients were analyzed to search for rare variants in hearing loss genes in a case-control study. A total of 109 patients with MD (73 familial cases and 36 early-onset sporadic patients) diagnosed according to the diagnostic criteria defined by the Barany Society were recruited in 11 hospitals. The allelic frequencies of rare variants in hearing loss genes were calculated in individuals with familial MD. A single rare variant analysis and a gene burden analysis (GBA) were conducted in the dataset selecting 1 patient from each family. Allelic frequencies from European and Spanish reference datasets were used as controls. RESULTS A total of 5136 single-nucleotide variants in hearing loss genes were considered for single rare variant analysis in familial MD cases, but only 1 heterozygous likely pathogenic variant in the OTOG gene (rs552304627) was found in 2 unrelated families. The gene burden analysis found an enrichment of rare missense variants in the OTOG gene in familial MD. So, 15 of 46 families (33%) showed at least 1 rare missense variant in the OTOG gene, suggesting a key role in familial MD. CONCLUSIONS The authors found an enrichment of multiplex rare missense variants in the OTOG gene in familial MD. This finding supports OTOG as a relevant gene in familial MD and set the groundwork for genetic testing in MD.
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Affiliation(s)
- 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, Granada, Spain
| | - Alvaro Gallego-Martinez
- Otology & Neurotology Group CTS 495, Department of Genomic Medicine, Centro Pfizer-Universidad de Granada-Junta de Andalucía de Genómica e Investigación Oncológica, Granada, Spain
| | - Andrés Soto-Varela
- Division of Otoneurology, Department of Otorhinolaryngology, Complexo Hospitalario Universitario, Santiago de Compostela, Spain
| | - Ismael Aran
- Department of Otolaryngology, Complexo Hospitalario de Pontevedra, Pontevedra, Spain
| | - Maria Del Carmen Moleon
- Department of Otolaryngology, Instituto de Investigación Biosanitaria, ibs.GRANADA, Hospital Universitario Virgen de las Nieves, Granada, Spain
| | - Juan Manuel Espinosa-Sanchez
- Department of Otolaryngology, Instituto de Investigación Biosanitaria, ibs.GRANADA, Hospital Universitario Virgen de las Nieves, Granada, Spain
| | | | - Angel Batuecas-Caletrio
- Department of Otolaryngology, Hospital Universitario Salamanca, Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain
| | - Paz Perez-Vazquez
- Department of Otorhinolaryngology, Hospital Universitario de Cabueñes, Gijón, Spain
| | - 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, Granada, Spain
- Department of Otolaryngology, Instituto de Investigación Biosanitaria, ibs.GRANADA, Hospital Universitario Virgen de las Nieves, Granada, Spain
- Department of Surgery, Division of Otolaryngology, Universidad de Granada, Granada, Spain
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Fritz D, Ferwerda B, Brouwer MC, van de Beek D. Whole genome sequencing identifies variants associated with sarcoidosis in a family with a high prevalence of sarcoidosis. Clin Rheumatol 2021; 40:3735-3743. [PMID: 33903979 PMCID: PMC8357727 DOI: 10.1007/s10067-021-05684-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 12/23/2020] [Accepted: 01/03/2021] [Indexed: 02/07/2023]
Abstract
Objective We studied genetic risk factors associated with sarcoidosis within a family with a high prevalence of this disease. Methods We studied 41 members of a family with a high rate of sarcoidosis, including an index patient with treatment-resistant neurosarcoidosis. Whole genome sequencing was performed for six affected family members and variations associated with loss of function were filtered out as candidate genes. Findings were validated by using amplicon sequencing within all 41 family members with DNA available and candidate genes were screened on absence and presence within the sarcoidosis affected and non-affected. Results Family members (n = 61) from 5 generations were available for participation including 13 subjects diagnosed with sarcoidosis (20%). Analyses identified 36 candidate variants within 34 candidate genes. Variations within three of these genes (JAK2, BACH2, and NCF1) previously have been associated with autoimmune diseases. Conclusions We identified 34 genes with a possible role in the etiology of sarcoidosis, including JAK2. Our results may suggest evaluation of JAK inhibitors in treatment-resistant sarcoidosis.
Key Points • JAK2 has a potential role in the etiology of sarcoidosis and is a potential therapeutic target. • We identified 33 additional candidate genes of which BACH2 and NCF1 have been previously associated with autoimmune disease. |
Supplementary Information The online version contains supplementary material available at 10.1007/s10067-021-05684-w.
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Affiliation(s)
- Daan Fritz
- Department of Neurology, Amsterdam Neuroscience, University of Amsterdam, Amsterdam UMC, P.O. Box 22660, Meibergdreef 9, 1100 DD, Amsterdam, The Netherlands
| | - Bart Ferwerda
- Department of Neurology, Amsterdam Neuroscience, University of Amsterdam, Amsterdam UMC, P.O. Box 22660, Meibergdreef 9, 1100 DD, Amsterdam, The Netherlands
| | - Matthijs C Brouwer
- Department of Neurology, Amsterdam Neuroscience, University of Amsterdam, Amsterdam UMC, P.O. Box 22660, Meibergdreef 9, 1100 DD, Amsterdam, The Netherlands
| | - Diederik van de Beek
- Department of Neurology, Amsterdam Neuroscience, University of Amsterdam, Amsterdam UMC, P.O. Box 22660, Meibergdreef 9, 1100 DD, Amsterdam, The Netherlands.
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Reliability of Serological Prestin Levels in Humans and its Relation to Otoacoustic Emissions, a Functional Measure of Outer Hair Cells. Ear Hear 2021; 42:1151-1162. [PMID: 33859120 DOI: 10.1097/aud.0000000000001026] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES Serological biomarkers, common to many areas of medicine, have the potential to inform on the health of the human body and to give early warning of risk of compromised function or illness before symptoms are experienced. Serological measurement of prestin, a motor protein uniquely produced and expressed in outer hair cells, has recently been identified as a potential biomarker to inform on the health of the cochlea. Before any test can be introduced into the clinical toolkit, the reproducibility of the measurement when repeated in the same subject must be considered. The primary objective of this study is to outline the test-retest reliability estimates and normative ranges for serological prestin in healthy young adults with normal hearing. In addition, we examine the relation between serum prestin levels and otoacoustic emissions (OAEs) to compare this OHC-specific protein to the most common measure of OHC function currently used in hearing assessments. DESIGN We measured prestin levels serologically from circulating blood in 34 young adults (18 to 24 years old) with clinically normal pure-tone audiometric averages at five different timepoints up to six months apart (average intervals between measurements ranged from <1 week to 7 weeks apart). To guide future studies of clinical populations, we present the standard error of the measurement, reference normative values, and multiple measures of reliability. Additionally, we measured transient evoked OAEs at the same five timepoints and used correlation coefficients to examine the relation between OAEs and prestin levels (pg/mL). RESULTS Serum prestin levels demonstrated good to excellent reliability between and across the five different time points, with correlation coefficients and intraclass correlations >0.8. Across sessions, the average serum prestin level was 250.20 pg/mL, with a standard error of measurement of 7.28 pg/mL. Moreover, positive correlations (generally weak to moderate) were found between prestin levels and OAE magnitudes and signal-to-noise ratios. CONCLUSIONS Findings characterize serum prestin in healthy young adults with normal hearing and provide initial normative data that may be critical to interpreting results from individuals with sensorineural hearing loss. Our results demonstrate reliability of serum prestin levels in a sample of normal-hearing young adults across five test sessions up to 6 months apart, paving the way for testing larger samples to more accurately estimate test-retest standards for clinical protocols, including those involving serial monitoring. The positive correlations between serum prestin and OAE levels, although weak to moderate, reinforce that the source of serum prestin is likely the outer hair cells in the inner ear, but also that serum prestin and OAEs each may also index aspects of biologic function not common to the other.
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Xu Y, Yang L, Zhao X, Zhang Y, Jones TA, Jones SM, Lundberg YW. Functional cooperation between two otoconial proteins Oc90 and Nox3. J Vestib Res 2021; 31:441-449. [PMID: 33554930 DOI: 10.3233/ves-201591] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Otoconia-related vertigo and balance deficits are common in humans, but the molecular etiology is unknown at present. OBJECTIVE In order to study mechanisms of otoconia formation and maintenance, we have investigated whether otoconin-90 (Oc90), the predominant otoconial constituent protein, and the NADPH oxidase Nox3, an essential regulatory protein for otoconia formation, are functionally interlinked. METHODS We performed balance behavioral, electrophysiological, morphological and molecular cellular analyses. RESULTS Double heterozygous mutant mice for Oc90 and Nox3 show severe imbalance, albeit less profound than double null mutants. In contrast, single heterozygous mutant mice have normal balance. Double heterozygous mice have otoconia defects and double null mice have no otoconia. In addition, some hair bundles in the latter mice go through accelerated degeneration. In vitro calcification analysis in cells stably expressing these proteins singly and doubly shows much more intense calcification in the double transfectants. CONCLUSIONS Oc90 and Nox3 augment each other's function, which is not only critical for otoconia formation but also for hair bundle maintenance.
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Affiliation(s)
- Yinfang Xu
- Vestibular Genetics Laboratory, Boys Town National Research Hospital, Omaha, NE, USA
| | - Liping Yang
- Vestibular Genetics Laboratory, Boys Town National Research Hospital, Omaha, NE, USA.,Current address: Changsha Environmental Protection College, 10 Jinggui Rd, Yuhua Qu, Changsha, Hunan, China
| | - Xing Zhao
- Vestibular Genetics Laboratory, Boys Town National Research Hospital, Omaha, NE, USA
| | - Yan Zhang
- Vestibular Genetics Laboratory, Boys Town National Research Hospital, Omaha, NE, USA
| | - Timothy A Jones
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Sherri M Jones
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Yunxia Wang Lundberg
- Vestibular Genetics Laboratory, Boys Town National Research Hospital, Omaha, NE, USA
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Gu S, Olszewski R, Taukulis I, Wei Z, Martin D, Morell RJ, Hoa M. Characterization of rare spindle and root cell transcriptional profiles in the stria vascularis of the adult mouse cochlea. Sci Rep 2020; 10:18100. [PMID: 33093630 PMCID: PMC7581811 DOI: 10.1038/s41598-020-75238-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 10/12/2020] [Indexed: 12/20/2022] Open
Abstract
The stria vascularis (SV) in the cochlea generates and maintains the endocochlear potential, thereby playing a pivotal role in normal hearing. Knowing transcriptional profiles and gene regulatory networks of SV cell types establishes a basis for studying the mechanism underlying SV-related hearing loss. While we have previously characterized the expression profiles of major SV cell types in the adult mouse, transcriptional profiles of rare SV cell types remained elusive due to the limitation of cell capture in single-cell RNA-Seq. The role of these rare cell types in the homeostatic function of the adult SV remain largely undefined. In this study, we performed single-nucleus RNA-Seq on the adult mouse SV in conjunction with sample preservation treatments during the isolation steps. We distinguish rare SV cell types, including spindle cells and root cells, from other cell types, and characterize their transcriptional profiles. Furthermore, we also identify and validate novel specific markers for these rare SV cell types. Finally, we identify homeostatic gene regulatory networks within spindle and root cells, establishing a basis for understanding the functional roles of these cells in hearing. These novel findings will provide new insights for future work in SV-related hearing loss and hearing fluctuation.
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Affiliation(s)
- Shoujun Gu
- Auditory Development and Restoration Program, National Institutes on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, 35 Convent Dr., Room 1F-226, Bethesda, MD, 20892, USA
| | - Rafal Olszewski
- Auditory Development and Restoration Program, National Institutes on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, 35 Convent Dr., Room 1F-226, Bethesda, MD, 20892, USA
| | - Ian Taukulis
- Auditory Development and Restoration Program, National Institutes on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, 35 Convent Dr., Room 1F-226, Bethesda, MD, 20892, USA
| | - Zheng Wei
- Biomedical Research Informatics Office, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD, 20892, USA
| | - Daniel Martin
- Biomedical Research Informatics Office, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD, 20892, USA
| | - Robert J Morell
- Computational Biology and Genomics Core, National Institutes on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Michael Hoa
- Auditory Development and Restoration Program, National Institutes on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, 35 Convent Dr., Room 1F-226, Bethesda, MD, 20892, USA.
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Compound Phenotype Due to Recessive Variants in LARP7 and OTOG Genes Disclosed by an Integrated Approach of SNP-Array and Whole Exome Sequencing. Genes (Basel) 2020; 11:genes11040379. [PMID: 32244554 PMCID: PMC7230222 DOI: 10.3390/genes11040379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 03/25/2020] [Accepted: 03/29/2020] [Indexed: 12/20/2022] Open
Abstract
Neurodevelopmental disorders are a challenge in medical genetics due to genetic heterogeneity and complex genotype-phenotype correlations. For this reason, the resolution of single cases not belonging to well-defined syndromes often requires an integrated approach of multiple whole-genome technologies. Such an approach has also unexpectedly revealed a complex molecular basis in an increasing number of patients, for whom the original suspect of a pleiotropic syndrome has been resolved as the summation effect of multiple genes. We describe a 10-year-old boy, the third son of first-cousin parents, with global developmental delay, facial dysmorphism, and bilateral deafness. SNP-array analysis revealed regions of homozygosity (ROHs) in multiple chromosome regions. Whole-exome sequencing prioritized on gene-mapping into the ROHs showed homozygosity for the likely pathogenic c.1097_1098delAG p. (Arg366Thrfs*2) frameshift substitution in LARP7 and the likely pathogenic c.5743C>T p.(Arg1915*) nonsense variant in OTOG. Recessive variants in LARP7 cause Alazami syndrome, while variants in OTOG cause an extremely rare autosomal recessive form of neurosensorial deafness. Previously unreported features were acrocyanosis and palmoplantar hyperhidrosis. This case highlights the utility of encouraging technological updates in medical genetics laboratories involved in the study of neurodevelopmental disorders and integrating laboratory outputs with the competencies of next-generation clinicians.
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22
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Schade-Mann T, Münkner S, Eckrich T, Engel J. Calcium signaling in interdental cells during the critical developmental period of the mouse cochlea. Hear Res 2020; 389:107913. [PMID: 32120242 DOI: 10.1016/j.heares.2020.107913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 02/04/2020] [Accepted: 02/07/2020] [Indexed: 11/18/2022]
Abstract
The tectorial membrane (TM), a complex acellular structure that covers part of the organ of Corti and excites outer hair cells, is required for normal hearing. It consists of collagen fibrils and various glycoproteins, which are synthesized in embryonic and postnatal development by different cochlear cell types including the interdental cells (IDCs). At its modiolar side, the TM is fixed to the apical surfaces of IDCs, which form the covering epithelium of the spiral limbus. We performed confocal membrane imaging and Ca2+ imaging in IDCs of the developing mouse cochlea from birth to postnatal day 18 (P18). Using the fluorescent membrane markers FM 4-64 and CellMask™ Deep Red on explanted whole-mount cochlear epithelium, we identified the morphology of IDCs at different z-levels of the spiral limbus. Ca2+ imaging of Fluo-8 AM-loaded cochlear epithelia revealed spontaneous intracellular Ca2+ transients in IDCs at P0/1, P4/5, and P18. Their relative frequency was lowest on P0/1, increased by a factor of 12.5 on P4/5 and decreased to twice the initial value on P18. At all three ages, stimulation of IDCs with the trinucleotides ATP and UTP at 1 and 10 μM elicited Ca2+ transients of varying amplitude and shape. Before the onset of hearing, IDCs responded with robust Ca2+ oscillations. At P18, after the onset of hearing, ATP stimulation either caused Ca2+ oscillations or an initial Ca2+ peak followed by a plateau while the UTP response was unchanged from that at pre-hearing stage. Parameters of spontaneous and nucleotide-evoked Ca2+ transients such as amplitude, decay time and duration were markedly reduced during cochlear development, whereas the kinetics of the Ca2+ rise did not show relevant changes. Whether low-frequency spontaneous Ca2+ transients are necessary for the formation and maintenance of the tectorial membrane e.g. by regulating gene transcription needs to be elucidated in further studies.
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Affiliation(s)
- Thore Schade-Mann
- Dept. of Biophysics & CIPMM, Hearing Research, Saarland University, Homburg, Germany; Department of Otolaryngology, Head and Neck Surgery, Tübingen University Medical Centre, Germany
| | - Stefan Münkner
- Dept. of Biophysics & CIPMM, Hearing Research, Saarland University, Homburg, Germany
| | - Tobias Eckrich
- Dept. of Biophysics & CIPMM, Hearing Research, Saarland University, Homburg, Germany
| | - Jutta Engel
- Dept. of Biophysics & CIPMM, Hearing Research, Saarland University, Homburg, Germany.
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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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Negishi-Oshino R, Ohgami N, He T, Li X, Kato M, Kobayashi M, Gu Y, Komuro K, Angelidis CE, Kato M. Heat shock protein 70 is a key molecule to rescue imbalance caused by low-frequency noise. Arch Toxicol 2019; 93:3219-3228. [PMID: 31576414 DOI: 10.1007/s00204-019-02587-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 09/26/2019] [Indexed: 01/27/2023]
Abstract
A previous study showed that people living in urban areas are generally exposed to low-frequency noise (LFN) with frequencies below 100 Hz and sound levels of 60-110 dB in daily and occupational environments. Exposure to LFN has been shown to affect balance in humans and mice. However, there is no information about prevention of LFN-mediated imbalance because of a lack of information about the target region based on health risk assessment of LFN exposure. Here, we show that acute exposure to LFN at 100 Hz, 95 dB, but not at 85 dB or 90 dB, for only 1 h caused imbalance in mice. The exposed mice also had decreased cervical vestibular-evoked myogenic potential (cVEMP) with impaired activity of vestibular hair cells. Since imbalance in the exposed mice was irreversible, morphological damage in the vestibules of the exposed mice was further examined. The exposed mice had breakage of the otoconial membrane in the vestibule. LFN-mediated imbalance and breakage of the otoconial membrane in mice were rescued by overexpression of a stress-reactive molecular chaperone, heat shock protein 70 (Hsp70), which has been shown to be induced by exposure of mice to 12 h per day of LFN at 95 dB for 5 days. Taken together, the results of this study demonstrate that acute exposure to LFN at 100 Hz, 95 dB for only 1 h caused irreversible imbalance in mice with structural damage of the otoconial membrane as the target region for LFN-mediated imbalance, which can be rescued by Hsp70.
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Affiliation(s)
- Reina Negishi-Oshino
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
| | - Nobutaka Ohgami
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
| | - Tingchao He
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
| | - Xiang Li
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
| | - Masashi Kato
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya, 466-8555, Japan
| | - Masayoshi Kobayashi
- EPMA Laboratory, Niigata University Center for Instrumental Analysis, Gakkou-cho-dori 2-5274, Niigata, 951-8514, Japan
| | - Yishuo Gu
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
| | - Kanako Komuro
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
| | | | - Masashi Kato
- Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan.
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Clinical characteristics with long-term follow-up of four Okinawan families with moderate hearing loss caused by an OTOG variant. Hum Genome Var 2019; 6:37. [PMID: 31645975 PMCID: PMC6804730 DOI: 10.1038/s41439-019-0068-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 06/28/2019] [Accepted: 07/01/2019] [Indexed: 11/29/2022] Open
Abstract
We describe the clinical features of four Japanese families with moderate sensorineural hearing loss due to the OTOG gene variant. We analyzed 98 hearing loss-related genes in patients with hearing loss originally from the Okinawa Islands using next-generation sequencing. We identified a homozygous variant of the gene encoding otogelin NM_001277269(OTOG): c.330C>G, p.Tyr110* in four families. All patients had moderate hearing loss with a slightly downsloping audiogram, including low frequency hearing loss without equilibrium dysfunction. Progressive hearing loss was not observed over the long-term in any patient. Among the three patients who underwent newborn hearing screening, two patients passed the test. OTOG-associated hearing loss was considered to progress early after birth, leading to moderate hearing loss and the later stable phase of hearing loss. Therefore, there are patients whose hearing loss cannot be detected by NHS, making genetic diagnosis of OTOG variants highly useful for complementing NHS in the clinical setting. Based on the allele frequency results, hearing loss caused by the p.Tyr110* variant in OTOG might be more common than we identified. The p.Tyr110* variant was reported in South Korea, suggesting that this variant is a common cause of moderate hearing loss in Japanese and Korean populations. People born with mutations in a gene linked to moderate hearing loss don’t always show problems during newborn hearing screening and may benefit from genetic screening. Testing for this gene, OTOG, which encodes a protein expressed in sensory cells of the inner ear, could thus be an important complement to newborn hearing screening for individuals with a family history of hearing loss who may benefit from early medical intervention. A Japan-based team led by Akira Ganaha from the University of Miyazaki studied seven patients with hearing loss from four unrelated families living on the Japanese archipelago of Okinawa. Each had two copies of a recessive mutation in OTOG, a variant previously documented only in South Korea. Of the three who underwent newborn hearing tests, only one was diagnosed with hearing deficiency at birth.
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26
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Donner I, Katainen R, Kaasinen E, Aavikko M, Sipilä LJ, Pukkala E, Aaltonen LA. Candidate susceptibility variants in angioimmunoblastic T-cell lymphoma. Fam Cancer 2019; 18:113-119. [PMID: 30097855 DOI: 10.1007/s10689-018-0099-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Angioimmunoblastic T-cell lymphoma (AITL) is a subtype of peripheral T-cell lymphoma with a poor prognosis: the 5-year survival rate is approximately 30%. Somatic driver mutations have been found in TET2, IDH2, DNMT3A, RHOA, FYN, PLCG1, and CD28, whereas germline susceptibility to AITL has to our knowledge not been studied. The homogenous Finnish population is well suited for studies on genetic predisposition. Here, we performed an exome-wide rare variant analysis in 23 AITL patients. No germline mutations were found in the driver genes, implying that they are not frequently involved in genetic AITL predisposition. Potentially pathogenic variants present in at least two patients and showing significant (p < 0.01) enrichment in our sample set were found in ten genes: POLK, PRKCB, ZNF676, PRRC2B, PCDHGB6, GNL3L, TTC36, OTOG, OSGEPL1, and RASSF9. The most significantly enriched variants, causing p.Lys469Ter in a splice variant of POLK and p.Pro588His in PRKCB, are intriguing candidates as Polk deficient mice display a spontaneous mutator phenotype, whereas PRKCB was recently shown to be somatically mutated in 33% of another peripheral T-cell lymphoma, adult T-cell lymphoma. If validated, our findings would provide new insight into the pathogenesis of AITL, as well as tools for early detection in susceptible individuals.
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Affiliation(s)
- Iikki Donner
- Department of Medical and Clinical Genetics, Medicum, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Genome-Scale Biology Research Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Riku Katainen
- Department of Medical and Clinical Genetics, Medicum, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Genome-Scale Biology Research Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Eevi Kaasinen
- Department of Medical and Clinical Genetics, Medicum, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Genome-Scale Biology Research Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Division of Functional Genomics and Systems Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Mervi Aavikko
- Department of Medical and Clinical Genetics, Medicum, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Genome-Scale Biology Research Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Lauri J Sipilä
- Department of Medical and Clinical Genetics, Medicum, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Genome-Scale Biology Research Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Eero Pukkala
- Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Helsinki, Finland.,Faculty of Social Sciences, University of Tampere, Tampere, Finland
| | - Lauri A Aaltonen
- Department of Medical and Clinical Genetics, Medicum, Faculty of Medicine, University of Helsinki, Helsinki, Finland. .,Genome-Scale Biology Research Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
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27
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Xie X, Yang Y, Ren Q, Ding X, Bao P, Yan B, Yan X, Han J, Yan P, Qiu Q. Accumulation of deleterious mutations in the domestic yak genome. Anim Genet 2018; 49:384-392. [DOI: 10.1111/age.12703] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/10/2018] [Indexed: 12/19/2022]
Affiliation(s)
- X. Xie
- State Key Laboratory of Grassland Agro-Ecosystem; School of Life Sciences; Lanzhou University; Lanzhou 730000 China
| | - Y. Yang
- State Key Laboratory of Grassland Agro-Ecosystem; School of Life Sciences; Lanzhou University; Lanzhou 730000 China
| | - Q. Ren
- State Key Laboratory of Grassland Agro-Ecosystem; School of Life Sciences; Lanzhou University; Lanzhou 730000 China
| | - X. Ding
- Key Laboratory of Yak Breeding Engineering Gansu Province; Lanzhou Institute of Husbandry and Pharmaceutical Sciences; Chinese Academy of Agricultural Science; Lanzhou 730050 China
| | - P. Bao
- Key Laboratory of Yak Breeding Engineering Gansu Province; Lanzhou Institute of Husbandry and Pharmaceutical Sciences; Chinese Academy of Agricultural Science; Lanzhou 730050 China
| | - B. Yan
- State Key Laboratory of Grassland Agro-Ecosystem; School of Life Sciences; Lanzhou University; Lanzhou 730000 China
| | - X. Yan
- State Key Laboratory of Grassland Agro-Ecosystem; School of Life Sciences; Lanzhou University; Lanzhou 730000 China
| | - J. Han
- State Key Laboratory of Grassland Agro-Ecosystem; School of Life Sciences; Lanzhou University; Lanzhou 730000 China
| | - P. Yan
- Key Laboratory of Yak Breeding Engineering Gansu Province; Lanzhou Institute of Husbandry and Pharmaceutical Sciences; Chinese Academy of Agricultural Science; Lanzhou 730050 China
| | - Q. Qiu
- State Key Laboratory of Grassland Agro-Ecosystem; School of Life Sciences; Lanzhou University; Lanzhou 730000 China
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28
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Garza-Lopez E, Lopez JA, Hagen J, Sheffer R, Meiner V, Lee A. Role of a conserved glutamine in the function of voltage-gated Ca 2+ channels revealed by a mutation in human CACNA1D. J Biol Chem 2018; 293:14444-14454. [PMID: 30054272 DOI: 10.1074/jbc.ra118.003681] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 07/24/2018] [Indexed: 12/11/2022] Open
Abstract
Voltage-gated Cav Ca2+ channels play crucial roles in regulating gene transcription, neuronal excitability, and synaptic transmission. Natural or pathological variations in Cav channels have yielded rich insights into the molecular determinants controlling channel function. Here, we report the consequences of a natural, putatively disease-associated mutation in the CACNA1D gene encoding the pore-forming Cav1.3 α1 subunit. The mutation causes a substitution of a glutamine residue that is highly conserved in the extracellular S1-S2 loop of domain II in all Cav channels with a histidine and was identified by whole-exome sequencing of an individual with moderate hearing impairment, developmental delay, and epilepsy. When introduced into the rat Cav1.3 cDNA, Q558H significantly decreased the density of Ca2+ currents in transfected HEK293T cells. Gating current analyses and cell-surface biotinylation experiments suggested that the smaller current amplitudes caused by Q558H were because of decreased numbers of functional Cav1.3 channels at the cell surface. The substitution also produced more sustained Ca2+ currents by weakening voltage-dependent inactivation. When inserted into the corresponding locus of Cav2.1, the substitution had similar effects as in Cav1.3. However, the substitution introduced in Cav3.1 reduced current density, but had no effects on voltage-dependent inactivation. Our results reveal a critical extracellular determinant of current density for all Cav family members and of voltage-dependent inactivation of Cav1.3 and Cav2.1 channels.
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Affiliation(s)
- Edgar Garza-Lopez
- From the Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, and Neurology and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242 and
| | - Josue A Lopez
- From the Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, and Neurology and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242 and
| | - Jussara Hagen
- From the Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, and Neurology and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242 and
| | - Ruth Sheffer
- Department of Genetics and Metabolic Diseases, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - Vardiella Meiner
- Department of Genetics and Metabolic Diseases, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - Amy Lee
- From the Departments of Molecular Physiology and Biophysics, Otolaryngology Head-Neck Surgery, and Neurology and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242 and
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29
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Yu S, Choi HJ, Lee JS, Lee HJ, Rim JH, Choi JY, Gee HY, Jung J. A novel early truncation mutation in OTOG causes prelingual mild hearing loss without vestibular dysfunction. Eur J Med Genet 2018; 62:81-84. [PMID: 29800624 DOI: 10.1016/j.ejmg.2018.05.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Revised: 05/09/2018] [Accepted: 05/21/2018] [Indexed: 01/30/2023]
Abstract
OTOG was identified as a nonsyndrmoic hearing loss gene in 2012 in two families with nonprogressive mild-to-moderate hearing loss. However, no further literature have this gene for nonsyndromic hearing loss. Furthermore, it is still unclear whether vestibular impairment is involved or not in patients with mutations in OTOG. This study presents a validated second report for homozygous causative mutations in OTOG of mild hearing loss. Whole exome sequencing (WES) was performed in a five-year-old male proband with mild hearing loss. The analysis of WES revealed a homozygous truncating mutation (c.330C > G; p.Tyr110*) in OTOG. The identified novel mutation, p.Tyr110*, leads to a null allele based on the fact that early truncated protein contains no functional domain of otogelin. While defects in otogelin previously reported to result in hearing loss and vestibular dysfunction, p.Tyr110* only caused nonsydromic and nonprogressive hearing loss without any vestibular impairment, indicating that vestibular phenotype would be variable. Given that mild hearing loss is not easy to be detected early, mutations of OTOG may be more prevalent than reported. Therefore, genetic evaluation for OTOG should be considered in children with mild hearing loss with/without vestibular dysfunction.
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Affiliation(s)
- Seyoung Yu
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
| | - Hye Ji Choi
- Department of Otorhinolaryngology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
| | - Joon Suk Lee
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
| | - Hyun Jae Lee
- Department of Otorhinolaryngology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
| | - John Hoon Rim
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
| | - Jae Young Choi
- Department of Otorhinolaryngology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
| | - Heon Yung Gee
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea.
| | - Jinsei Jung
- Department of Otorhinolaryngology, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea.
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30
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Goodyear RJ, Richardson GP. Structure, Function, and Development of the Tectorial Membrane: An Extracellular Matrix Essential for Hearing. Curr Top Dev Biol 2018; 130:217-244. [PMID: 29853178 DOI: 10.1016/bs.ctdb.2018.02.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The tectorial membrane is an extracellular matrix that lies over the apical surface of the auditory epithelia in the inner ears of reptiles, birds, and mammals. Recent studies have shown it is composed of a small set of proteins, some of which are only produced at high levels in the ear and many of which are the products of genes that, when mutated, cause nonsyndromic forms of human hereditary deafness. Quite how the proteins of the tectorial membrane are assembled within the lumen of the inner ear to form a structure that is precisely regulated in its size and physical properties along the length of a tonotopically organized hearing organ is a question that remains to be fully answered. In this brief review we will summarize what is known thus far about the structure, protein composition, and function of the tectorial membrane in birds and mammals, describe how the tectorial membrane develops, and discuss major events that have occurred during the evolution of this extracellular matrix.
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Affiliation(s)
- Richard J Goodyear
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Guy P Richardson
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom.
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31
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Jain RK, Pingle SK, Tumane RG, Thakkar LR, Jawade AA, Barapatre A, Trivedi M. Cochlear Proteins Associated with Noise-induced Hearing Loss: An Update. Indian J Occup Environ Med 2018; 22:60-73. [PMID: 30319226 PMCID: PMC6176698 DOI: 10.4103/ijoem.ijoem_43_18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Noise-induced hearing loss (NIHL) is one of the major occupational disease that has influence on the quality of life of mining workers. Several reports suggest NIHL is attributed to noise exposure at workplace and approximately 16% of hearing loss is due to it. NIHL occurs as a result of exposure to high-level noise (>85 dB) in the workplace. Noise disrupts proteins present in the micromachinery of the ear that is required for mechano-electric transduction of sound waves. High-level noise exposure can lead to hearing impairment owing to mechanical and metabolic exhaustion in cochlea, the major organ responsible for resilience of sound. Several key proteins of cochlea include tectorial membrane, inner hair cells, outer hair cells, and stereocilia are damaged due to high-level noise exposure. Numerous studies conducted in animals have shown cochlear proteins involvement in NIHL, but the pertinent literature remains limited in humans. Detection of proteins and pathways perturbed within the micromachinery of the ear after excessive sound induction leads toward the early identification of hearing loss. The situation insisted to present this review as an update on cochlear proteins associated with NIHL after an extensive literature search using several electronic databases which help to understand the pathophysiology of NIHL.
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Affiliation(s)
- Ruchika K Jain
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Shubhangi K Pingle
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Rajani G Tumane
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Lucky R Thakkar
- National Centre for Microbial Resources, National Centre for Cell Science, University of Pune Campus, Pune, Maharashtra, India
| | - Aruna A Jawade
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Anand Barapatre
- Department of Biochemistry, National Institute of Miners' Health JNARDDC Campus, Wadi, Nagpur, Maharashtra, India
| | - Minal Trivedi
- B. K. Birla College of Science, Arts & Commerce (Autonomous), Kalyan, Maharashtra, India
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Heterogeneous Patterns of Genetic Diversity and Differentiation in European and Siberian Chiffchaff ( Phylloscopus collybita abietinus/P. tristis). G3-GENES GENOMES GENETICS 2017; 7:3983-3998. [PMID: 29054864 PMCID: PMC5714495 DOI: 10.1534/g3.117.300152] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Identification of candidate genes for trait variation in diverging lineages and characterization of mechanistic underpinnings of genome differentiation are key steps toward understanding the processes underlying the formation of new species. Hybrid zones provide a valuable resource for such investigations, since they allow us to study how genomes evolve as species exchange genetic material and to associate particular genetic regions with phenotypic traits of interest. Here, we use whole-genome resequencing of both allopatric and hybridizing populations of the European (Phylloscopus collybita abietinus) and the Siberian chiffchaff (P. tristis)—two recently diverged species which differ in morphology, plumage, song, habitat, and migration—to quantify the regional variation in genome-wide genetic diversity and differentiation, and to identify candidate regions for trait variation. We find that the levels of diversity, differentiation, and divergence are highly heterogeneous, with significantly reduced global differentiation, and more pronounced differentiation peaks in sympatry than in allopatry. This pattern is consistent with regional differences in effective population size and recurrent background selection or selective sweeps reducing the genetic diversity in specific regions prior to lineage divergence, but the data also suggest that postdivergence selection has resulted in increased differentiation and fixed differences in specific regions. We find that hybridization and backcrossing is common in sympatry, and that phenotype is a poor predictor of the genomic composition of sympatric birds. The combination of a differentiation scan approach with identification of fixed differences pinpoint a handful of candidate regions that might be important for trait variation between the two species.
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Barake R, Abou-Rizk S, Nemer G, Bassim M. The OTOGL p.Arg925* Variant is Associated with Moderate Hearing Loss in a Syrian Nonconsanguineous Family. Genet Test Mol Biomarkers 2017; 21:445-449. [PMID: 28426234 DOI: 10.1089/gtmb.2016.0406] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
AIM To screen for the genetic basis of congenital hearing loss in a Syrian family. METHODS A Syrian patient living in Lebanon presented with moderate congenital hearing loss. The patient's large nonconsanguineous family was recruited. DNA was extracted from blood samples and sent for whole-exome sequencing. A detailed clinical examination along with audiograms was obtained for all subjects. RESULTS Hearing loss was noted to be mild to moderate in the low and mid frequencies, sloping to moderate to severe in the high frequencies for all affected members. Results of DNA analysis showed the presence of a previously described p.Arg925* mutation in the OTOGL gene on both alleles in affected family members, whereas nonaffected members either had the wild type or one copy of the mutated allele. DISCUSSION Mutations affecting the OTOGL gene have been recently connected with nonsyndromic sensorineural hearing loss. Seven such mutations have already been described. The p.Arg925* reported in this study has been found once in a French family. The current report is the first to describe this mutation in a Middle Eastern family.
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Affiliation(s)
- Rana Barake
- 1 Department of Otolaryngology - Head & Neck Surgery, American University of Beirut , Beirut, Lebanon
| | - Samer Abou-Rizk
- 1 Department of Otolaryngology - Head & Neck Surgery, American University of Beirut , Beirut, Lebanon
| | - Georges Nemer
- 2 Department of Biochemistry and Molecular Genetics Faculty of Medicine, American University of Beirut , Beirut, Lebanon
| | - Marc Bassim
- 1 Department of Otolaryngology - Head & Neck Surgery, American University of Beirut , Beirut, Lebanon
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Delayed Otolith Development Does Not Impair Vestibular Circuit Formation in Zebrafish. J Assoc Res Otolaryngol 2017; 18:415-425. [PMID: 28332011 DOI: 10.1007/s10162-017-0617-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 02/21/2017] [Indexed: 10/19/2022] Open
Abstract
What is the role of normally patterned sensory signaling in development of vestibular circuits? For technical reasons, including the difficulty in depriving animals of vestibular inputs, this has been a challenging question to address. Here we take advantage of a vestibular-deficient zebrafish mutant, rock solo AN66 , in order to examine whether normal sensory input is required for formation of vestibular-driven postural circuitry. We show that the rock solo AN66 mutant is a splice site mutation in the secreted glycoprotein otogelin (otog), which we confirm through both whole genome sequencing and complementation with an otog early termination mutant. Using confocal microscopy, we find that elements of postural circuits are anatomically normal in rock solo AN66 mutants, including hair cells, vestibular ganglion neurons, and vestibulospinal neurons. Surprisingly, the balance and postural deficits that are readily apparent in younger larvae disappear around 2 weeks of age. We demonstrate that this behavioral recovery follows the delayed development of the anterior (utricular) otolith, which appears around 14 days post-fertilization (dpf), compared to 1 dpf in WT. These findings indicate that utricular signaling is not required for normal structural development of the inner ear and vestibular nucleus neurons. Furthermore, despite the otolith's developmental delay until well after postural behaviors normally appear, downstream circuits can drive righting reflexes within ∼1-2 days of its arrival, indicating that vestibular circuit wiring is not impaired by a delay in patterned activity. The functional recovery of postural behaviors may shed light on why humans with mutations in otog exhibit only subclinical vestibular deficits.
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Weigele J, Franz-Odendaal TA, Hilbig R. Formation of the inner ear during embryonic and larval development of the cichlid fish (Oreochromis mossambicus). Connect Tissue Res 2017; 58:172-195. [PMID: 27268076 DOI: 10.1080/03008207.2016.1198337] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND The vertebrate inner ear comprises mineralized elements, namely the otoliths (fishes) or the otoconia (mammals). These elements serve vestibular and auditory functions. The formation of otoconia and otoliths is described as a stepwise process, and in fish, it is generally divided into an aggregation of the otolith primordia from precursor particles and then a growth process that continues throughout life. RESULTS This study was undertaken to investigate the complex transition between these two steps. Therefore, we investigated the developmental profiles of several inner ear structural and calcium-binding proteins during the complete embryonic and larval development of the cichlid fish Oreochromis mossambicus in parallel with the morphology of inner ear and especially otoliths. We show that the formation of otoliths is a highly regulated temporal and spatial process which takes place throughout embryonic and larval development. CONCLUSIONS Based on our data we defined eight phases of otolith differentiation from the primordia to the mature otolith.
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Affiliation(s)
- Jochen Weigele
- a Zoological Institute , University of Stuttgart-Hohenheim , Stuttgart , Germany.,b Department of Biology , Mount Saint Vincent University , Halifax , Nova Scotia , Canada
| | | | - Reinhard Hilbig
- a Zoological Institute , University of Stuttgart-Hohenheim , Stuttgart , Germany
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Xu Y, Zhang Y, Lundberg YW. Spatiotemporal differences in otoconial gene expression. Genesis 2016; 54:613-625. [PMID: 27792272 DOI: 10.1002/dvg.22990] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 10/02/2016] [Accepted: 10/26/2016] [Indexed: 11/06/2022]
Abstract
Otoconia are minute biocrystals composed of glycoproteins, proteoglycans, and CaCO3 , and are indispensable for sensory processing in the utricle and saccule. Otoconia abnormalities and degeneration can cause or facilitate crystal dislocation to the ampulla, leading to vertigo and imbalance in humans. In order to better understand the molecular mechanism controlling otoconia formation and maintenance, we have examined the spatial and temporal expression differences of otoconial genes in the mouse inner ear at developmental, mature and aging stages using whole transcriptome sequencing (RNA-Seq) and quantitative RT-PCR. We show that the expression levels of most otoconial genes are much higher in the utricle and saccule compared with other inner ear tissues before postnatal stages in C57Bl/6J mice, and the expression of a few of these genes is restricted to the embryonic utricle and saccule. After the early postnatal stages, expression of all otoconial genes in the utricle and saccule is drastically reduced, while a few genes gain expression dominance in the aging ampulla, indicating a potential for ectopic debris formation in the latter tissue at old ages. The data suggest that the expression of otoconial genes is tightly regulated spatially and temporally during developmental stages and can become unregulated at aging stages. Birth Defects Research (Part A) 106:613-625, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Yinfang Xu
- Vestibular Genetics Laboratory, Center for Sensory Neuroscience, Boys Town National Research Hospital, Omaha, Nebraska, 68131, USA.,Cell Electrophysiology Laboratory, Shanghai Research Center of Acupuncture and Meridians, Shanghai, 201203, China
| | - Yan Zhang
- Vestibular Genetics Laboratory, Center for Sensory Neuroscience, Boys Town National Research Hospital, Omaha, Nebraska, 68131, USA
| | - Yunxia Wang Lundberg
- Vestibular Genetics Laboratory, Center for Sensory Neuroscience, Boys Town National Research Hospital, Omaha, Nebraska, 68131, USA
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BODIPY-Conjugated Xyloside Primes Fluorescent Glycosaminoglycans in the Inner Ear of Opsanus tau. J Assoc Res Otolaryngol 2016; 17:525-540. [PMID: 27619213 DOI: 10.1007/s10162-016-0585-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Accepted: 08/23/2016] [Indexed: 12/22/2022] Open
Abstract
We report on a new xyloside conjugated to BODIPY, BX and its utility to prime fluorescent glycosaminoglycans (BX-GAGs) within the inner ear in vivo. When BX is administered directly into the endolymphatic space of the oyster toadfish (Opsanus tau) inner ear, fluorescent BX-GAGs are primed and become visible in the sensory epithelia of the semicircular canals, utricle, and saccule. Confocal and 2-photon microscopy of vestibular organs fixed 4 h following BX treatment, reveal BX-GAGs constituting glycocalyces that envelop hair cell kinocilium, nerve fibers, and capillaries. In the presence of GAG-specific enzymes, the BX-GAG signals are diminished, suggesting that chondroitin sulfates are the primary GAGs primed by BX. Results are consistent with similar click-xylosides in CHO cell lines, where the xyloside enters the Golgi and preferentially initiates chondroitin sulfate B production. Introduction of BX produces a temporary block of hair cell mechanoelectrical transduction (MET) currents in the crista, reduction in background discharge rate of afferent neurons, and a reduction in sensitivity to physiological stimulation. A six-degree-of-freedom pharmacokinetic mathematical model has been applied to interpret the time course and spatial distribution of BX and BX-GAGs. Results demonstrate a new optical approach to study GAG biology in the inner ear, for tracking synthesis and localization in real time.
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Weigele J, Franz-Odendaal TA, Hilbig R. Not All Inner Ears are the Same: Otolith Matrix Proteins in the Inner Ear of Sub-Adult Cichlid Fish,Oreochromis Mossambicus, Reveal Insights Into the Biomineralization Process. Anat Rec (Hoboken) 2015; 299:234-45. [DOI: 10.1002/ar.23289] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 09/30/2015] [Accepted: 10/03/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Jochen Weigele
- Zoological Institute, University of Stuttgart-Hohenheim; Garbenstrasse 30 Stuttgart 73734 Germany
- Department of Biology; Mount Saint Vincent University; 166 Bedford Highway Halifax Nova Scotia B3M 2J6 Canada
| | - Tamara A. Franz-Odendaal
- Department of Biology; Mount Saint Vincent University; 166 Bedford Highway Halifax Nova Scotia B3M 2J6 Canada
| | - Reinhard Hilbig
- Zoological Institute, University of Stuttgart-Hohenheim; Garbenstrasse 30 Stuttgart 73734 Germany
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El Hakam Kamareddin C, Magnol L, Blanquet V. A new Otogelin ENU mouse model for autosomal-recessive nonsyndromic moderate hearing impairment. SPRINGERPLUS 2015; 4:730. [PMID: 26636018 PMCID: PMC4659790 DOI: 10.1186/s40064-015-1537-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 11/13/2015] [Indexed: 02/03/2023]
Abstract
Approximately 10 % of the population worldwide suffers from hearing loss (HL) and about 60 % of persons with early onset HL have hereditary hearing loss due to genetic mutations. Highly efficient mutagenesis in mice with the chemical mutagen, ethylnitrosourea (ENU), associated with relevant phenotypic tools represents a powerful approach in producing mouse models for hearing impairment. A benefit of this strategy is to generate alleles to form a series revealing the full spectrum of gene function in vivo. It can also mimic the range of human mutations and polymorphisms for HL. In the course of a genome ENU mutagenesis program, we selected a new mouse model for hearing defect based on a dysmorphological screen. We identified by gene mapping the mutation responsible for this phenotype and characterized it at the histological level of the inner ear and evaluated the vestibule by following the recommendations of the standard operating procedures, IMPReSS. We have identified and characterized a new recessive allele of the otogelin gene, Otogvbd/vbd, due to a homozygous one base pair substitution at the splice donor site of intron 29. This mutation leads to a frame-shift and a premature stop codon. We observed a decrease in the amount of sensory cells in the maculae of Otogvbd/vbd mice as well as an apparent drastically decreased density to almost absence of the otoconial membrane. Compared to Otogtm1Prs and twister, the two other existing otogelin alleles, the detailed analysis of Otogvbd/vbd revealed that these mice share some common behavioural characteristics either with Otogtm1Prs or twister whereas the fine vestibular phenotype and the hearing defect are different. Our results emphasize the importance of detecting and characterizing a new allele of a gene in order to get comprehensive information about the gene function.
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Affiliation(s)
- Carole El Hakam Kamareddin
- Univ. Limoges, INRA, UMR 1061, Unité de Génétique Moléculaire Animale, Faculté des Sciences et Techniques, 123, Avenue Albert Thomas, 87060 Limoges, France
| | - Laetitia Magnol
- Univ. Limoges, INRA, UMR 1061, Unité de Génétique Moléculaire Animale, Faculté des Sciences et Techniques, 123, Avenue Albert Thomas, 87060 Limoges, France
| | - Veronique Blanquet
- Univ. Limoges, INRA, UMR 1061, Unité de Génétique Moléculaire Animale, Faculté des Sciences et Techniques, 123, Avenue Albert Thomas, 87060 Limoges, France
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Molecular organization and fine structure of the human tectorial membrane: is it replenished? Cell Tissue Res 2015; 362:513-27. [PMID: 26085343 DOI: 10.1007/s00441-015-2225-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Accepted: 05/22/2015] [Indexed: 10/23/2022]
Abstract
Auditory sensitivity and frequency resolution depend on the physical properties of the basilar membrane in combination with outer hair cell-based amplification in the cochlea. The physiological role of the tectorial membrane (TM) in hair cell transduction has been controversial for decades. New insights into the TM structure and function have been gained from studies of targeted gene disruption. Several missense mutations in genes regulating the human TM structure have been described with phenotypic expressions. Here, we portray the remarkable gradient structure and molecular organization of the human TM. Ultrastructural analysis and confocal immunohistochemistry were performed in freshly fixed human cochleae obtained during surgery. Based on these findings and recent literature, we discuss the role of human TMs in hair cell activation. Moreover, the outcome proposes that the α-tectorin-positive amorphous layer of the human TM is replenished and partly undergoes regeneration during life.
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Stooke-Vaughan GA, Obholzer ND, Baxendale S, Megason SG, Whitfield TT. Otolith tethering in the zebrafish otic vesicle requires Otogelin and α-Tectorin. Development 2015; 142:1137-45. [PMID: 25758224 PMCID: PMC4360185 DOI: 10.1242/dev.116632] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Otoliths are biomineralised structures important for balance and hearing in fish. Their counterparts in the mammalian inner ear, otoconia, have a primarily vestibular function. Otoliths and otoconia form over sensory maculae and are attached to the otolithic membrane, a gelatinous extracellular matrix that provides a physical coupling between the otolith and the underlying sensory epithelium. In this study, we have identified two proteins required for otolith tethering in the zebrafish ear, and propose that there are at least two stages to this process: seeding and maintenance. The initial seeding step, in which otolith precursor particles tether directly to the tips of hair cell kinocilia, fails to occur in the einstein (eis) mutant. The gene disrupted in eis is otogelin (otog); mutations in the human OTOG gene have recently been identified as causative for deafness and vestibular dysfunction (DFNB18B). At later larval stages, maintenance of otolith tethering to the saccular macula is dependent on tectorin alpha (tecta) function, which is disrupted in the rolling stones (rst) mutant. α-Tectorin (Tecta) is a major constituent of the tectorial membrane in the mammalian cochlea. Mutations in the human TECTA gene can cause either dominant (DFNA8/12) or recessive (DFNB21) forms of deafness. Our findings indicate that the composition of extracellular otic membranes is highly conserved between mammals and fish, reinforcing the view that the zebrafish is an excellent model system for the study of deafness and vestibular disease.
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Affiliation(s)
| | - Nikolaus D Obholzer
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Sarah Baxendale
- Bateson Centre and Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
| | - Sean G Megason
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Tanya T Whitfield
- Bateson Centre and Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
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Nishio SY, Hattori M, Moteki H, Tsukada K, Miyagawa M, Naito T, Yoshimura H, Iwasa YI, Mori K, Shima Y, Sakuma N, Usami SI. Gene expression profiles of the cochlea and vestibular endorgans: localization and function of genes causing deafness. Ann Otol Rhinol Laryngol 2015; 124 Suppl 1:6S-48S. [PMID: 25814645 DOI: 10.1177/0003489415575549] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVES We sought to elucidate the gene expression profiles of the causative genes as well as the localization of the encoded proteins involved in hereditary hearing loss. METHODS Relevant articles (as of September 2014) were searched in PubMed databases, and the gene symbols of the genes reported to be associated with deafness were located on the Hereditary Hearing Loss Homepage using localization, expression, and distribution as keywords. RESULTS Our review of the literature allowed us to systematize the gene expression profiles for genetic deafness in the inner ear, clarifying the unique functions and specific expression patterns of these genes in the cochlea and vestibular endorgans. CONCLUSIONS The coordinated actions of various encoded molecules are essential for the normal development and maintenance of auditory and vestibular function.
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Affiliation(s)
- 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
| | - Mitsuru Hattori
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Hideaki Moteki
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Keita Tsukada
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Maiko Miyagawa
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
| | - Takehiko Naito
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Hidekane Yoshimura
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Yoh-Ichiro Iwasa
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Kentaro Mori
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Yutaka Shima
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Naoko Sakuma
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Otorhinolaryngology and Head and Neck Surgery, Yokohama City University School of Medicine, Yokohama, 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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Abstract
OBJECTIVES Recently, OTOG and OTOGL were identified as human deafness genes. Currently, only four families are known to have autosomal recessive hearing loss based on mutations in these genes. Because the two genes code for proteins (otogelin and otogelin-like) that are strikingly similar in structure and localization in the inner ear, this study is focused on characterizing and comparing the hearing loss caused by mutations in these genes. DESIGN To evaluate this type of hearing, an extensive set of audiometric and vestibular examinations was performed in the 13 patients from four families. RESULTS All families show a flat to downsloping configuration of the audiogram with mild to moderate sensorineural hearing loss. Speech recognition scores remain good (>90%). Hearing loss is not significantly different in the four families and the psychophysical test results also do not differ among the families. Vestibular examinations show evidence for vestibular hyporeflexia. CONCLUSION Because otogelin and otogelin-like are localized in the tectorial membrane, one could expect a cochlear conductive hearing loss, as was previously shown in DFNA13 (COL11A2) and DFNA8/12 (TECTA) patients. Results of psychophysical examinations, however, do not support this. Furthermore, the authors conclude that there are no phenotypic differences between hearing loss based on mutations in OTOG or OTOGL. This phenotype description will facilitate counseling of hearing loss caused by defects in either of these two genes.
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Jones GP, Elliott SJ, Russell IJ, Lukashkin AN. Modified protein expression in the tectorial membrane of the cochlea reveals roles for the striated sheet matrix. Biophys J 2015; 108:203-10. [PMID: 25564867 PMCID: PMC4286592 DOI: 10.1016/j.bpj.2014.11.1854] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 11/04/2014] [Accepted: 11/04/2014] [Indexed: 11/28/2022] Open
Abstract
The tectorial membrane (TM) of the mammalian cochlea is a complex extracellular matrix which, in response to acoustic stimulation, displaces the hair bundles of outer hair cells (OHCs), thereby initiating sensory transduction and amplification. Here, using TM segments from the basal, high-frequency region of the cochleae of genetically modified mice (including models of human hereditary deafness) with missing or modified TM proteins, we demonstrate that frequency-dependent stiffening is associated with the striated sheet matrix (SSM). Frequency-dependent stiffening largely disappeared in all three TM mutations studied where the SSM was absent either entirely or at least from the stiffest part of the TM overlying the OHCs. In all three TM mutations, dissipation of energy is decreased at low (<8 kHz) and increased at high (>8 kHz) stimulus frequencies. The SSM is composed of polypeptides carrying fixed charges, and electrostatic interaction between them may account for frequency-dependent stiffness changes in the material properties of the TM. Through comparison with previous in vivo measurements, it is proposed that implementation of frequency-dependent stiffening of the TM in the OHC attachment region facilitates interaction among tones, backward transmission of energy, and amplification in the cochlea.
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Affiliation(s)
- Gareth P Jones
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom
| | - Stephen J Elliott
- Institute of Sound and Vibration Research, University of Southampton, Southampton, United Kingdom
| | - Ian J Russell
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom.
| | - Andrei N Lukashkin
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom.
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Cupulin is a zona pellucida-like domain protein and major component of the cupula from the inner ear. PLoS One 2014; 9:e111917. [PMID: 25369234 PMCID: PMC4219815 DOI: 10.1371/journal.pone.0111917] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 10/09/2014] [Indexed: 11/19/2022] Open
Abstract
The extracellular membranes of the inner ear are essential constituents to maintain sensory functions, the cupula for sensing torsional movements of the head, the otoconial membrane for sensing linear movements and accelerations like gravity, and the tectorial membrane in the cochlea for hearing. So far a number of structural proteins have been described, but for the gelatinous cupula precise data are missing. Here, we describe for the first time a major proteinogenic component of the cupula structure with an apparent molecular mass of 45 kDa from salmon. Analyses of respective peptides revealed highly conserved amino-acid sequences with identity to zona pellucida-like domain proteins. Immunohistochemistry studies localized the protein in the ampulla of the inner ear from salmon and according to its anatomical appearance we identified this glycoprotein as Cupulin. Future research on structure and function of zona pellucida-like domain proteins will enhance our knowledge of inner ear diseases, like sudden loss of vestibular function and other disturbances.
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Lundberg YW, Xu Y, Thiessen KD, Kramer KL. Mechanisms of otoconia and otolith development. Dev Dyn 2014; 244:239-53. [PMID: 25255879 DOI: 10.1002/dvdy.24195] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 08/25/2014] [Accepted: 08/26/2014] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Otoconia are bio-crystals that couple mechanic forces to the sensory hair cells in the utricle and saccule, a process essential for us to sense linear acceleration and gravity for the purpose of maintaining bodily balance. In fish, structurally similar bio-crystals called otoliths mediate both balance and hearing. Otoconia abnormalities are common and can cause vertigo and imbalance in humans. However, the molecular etiology of these illnesses is unknown, as investigators have only begun to identify genes important for otoconia formation in recent years. RESULTS To date, in-depth studies of selected mouse otoconial proteins have been performed, and about 75 zebrafish genes have been identified to be important for otolith development. CONCLUSIONS This review will summarize recent findings as well as compare otoconia and otolith development. It will provide an updated brief review of otoconial proteins along with an overview of the cells and cellular processes involved. While continued efforts are needed to thoroughly understand the molecular mechanisms underlying otoconia and otolith development, it is clear that the process involves a series of temporally and spatially specific events that are tightly coordinated by numerous proteins. Such knowledge will serve as the foundation to uncover the molecular causes of human otoconia-related disorders.
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Affiliation(s)
- Yunxia Wang Lundberg
- Vestibular Genetics Laboratory, Boys Town National Research Hospital, Omaha, Nebraska
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47
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Lundberg YW, Xu Y, Thiessen KD, Kramer KL. Mechanisms of otoconia and otolith development. Dev Dyn 2014. [PMID: 25255879 DOI: 10.1002/dvdy.24195(2014)] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Otoconia are bio-crystals that couple mechanic forces to the sensory hair cells in the utricle and saccule, a process essential for us to sense linear acceleration and gravity for the purpose of maintaining bodily balance. In fish, structurally similar bio-crystals called otoliths mediate both balance and hearing. Otoconia abnormalities are common and can cause vertigo and imbalance in humans. However, the molecular etiology of these illnesses is unknown, as investigators have only begun to identify genes important for otoconia formation in recent years. RESULTS To date, in-depth studies of selected mouse otoconial proteins have been performed, and about 75 zebrafish genes have been identified to be important for otolith development. CONCLUSIONS This review will summarize recent findings as well as compare otoconia and otolith development. It will provide an updated brief review of otoconial proteins along with an overview of the cells and cellular processes involved. While continued efforts are needed to thoroughly understand the molecular mechanisms underlying otoconia and otolith development, it is clear that the process involves a series of temporally and spatially specific events that are tightly coordinated by numerous proteins. Such knowledge will serve as the foundation to uncover the molecular causes of human otoconia-related disorders.
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Affiliation(s)
- Yunxia Wang Lundberg
- Vestibular Genetics Laboratory, Boys Town National Research Hospital, Omaha, Nebraska
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Castellanos R, Xie Q, Zheng D, Cvekl A, Morrow BE. Mammalian TBX1 preferentially binds and regulates downstream targets via a tandem T-site repeat. PLoS One 2014; 9:e95151. [PMID: 24797903 PMCID: PMC4010391 DOI: 10.1371/journal.pone.0095151] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 03/24/2014] [Indexed: 11/20/2022] Open
Abstract
Haploinsufficiency or mutation of TBX1 is largely responsible for the etiology of physical malformations in individuals with velo-cardio-facial/DiGeorge syndrome (VCFS/DGS/22q11.2 deletion syndrome). TBX1 encodes a transcription factor protein that contains an evolutionarily conserved DNA binding domain termed the T-box that is shared with other family members. All T-box proteins, examined so far, bind to similar but not identical consensus DNA sequences, indicating that they have specific binding preferences. To identify the TBX1 specific consensus sequence, Systematic Evolution of Ligands by Exponential Enrichment (SELEX) was performed. In contrast to other TBX family members recognizing palindrome sequences, we found that TBX1 preferentially binds to a tandem repeat of 5′-AGGTGTGAAGGTGTGA-3′. We also identified a second consensus sequence comprised of a tandem repeat with a degenerated downstream site. We show that three known human disease-causing TBX1 missense mutations (F148Y, H194Q and G310S) do not alter nuclear localization, or disrupt binding to the tandem repeat consensus sequences, but they reduce transcriptional activity in cell culture reporter assays. To identify Tbx1-downstream genes, we performed an in silico genome wide analysis of potential cis-acting elements in DNA and found strong enrichment of genes required for developmental processes and transcriptional regulation. We found that TBX1 binds to 19 different loci in vitro, which may correspond to putative cis-acting binding sites. In situ hybridization coupled with luciferase gene reporter assays on three gene loci, Fgf8, Bmper, Otog-MyoD, show that these motifs are directly regulated by TBX1 in vitro. Collectively, the present studies establish new insights into molecular aspects of TBX1 binding to DNA. This work lays the groundwork for future in vivo studies, including chromatin immunoprecipitation followed by next generation sequencing (ChIP-Seq) to further elucidate the molecular pathogenesis of VCFS/DGS.
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Affiliation(s)
- Raquel Castellanos
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Qing Xie
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Ophthalmology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Deyou Zheng
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Neurology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Ales Cvekl
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Ophthalmology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Bernice E. Morrow
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
- * E-mail:
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Biallelic nonsense mutations in the otogelin-like gene (OTOGL) in a child affected by mild to moderate hearing impairment. Gene 2013; 527:537-40. [DOI: 10.1016/j.gene.2013.06.044] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 06/06/2013] [Accepted: 06/08/2013] [Indexed: 12/17/2022]
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Abstract
OBJECTIVES 1. Evaluate the otolithic membrane in patients with endolymphatic hydrops (EH) and vestibular drop attacks (VDA) undergoing ablative labyrinthectomy. 2. Correlate intraoperative findings to archival temporal bone specimens of patients with EH. STUDY DESIGN Retrospective case review. SETTING Tertiary referral center. SPECIMEN SOURCE: 1. Patients undergoing labyrinthectomy for incapacitating Ménière's disease (MD), delayed EH, VDA, or acoustic neuroma (AN) between 2004 and 2011. 2. Archival temporal bone specimens of patients with MD. INTERVENTIONS Ablative labyrinthectomy. MAIN OUTCOME MEASURES Examination of the utricular otolithic membrane. RESULTS The otolithic membrane of the utricle was evaluated intraoperatively in 28 patients undergoing labyrinthectomy. Seven (25%) had a history of VDA, 6 (21%) had delayed EH, 9 (32%) had MD, and 6 (21%) had AN. All patients with VDA showed evidence of a disrupted utricular otolithic membrane, whereas only 50% and 56% of patients with delayed EH and MD, respectively, demonstrated otolithic membrane disruption (p = 0.051). None of the patients with AN showed otolithic membrane disruption (p = 0.004). The mean thickness of the otolithic membrane in 5 archival temporal bone MD specimens was 11.45 micrometers versus 38 micrometers in normal specimens (p = 0.001). CONCLUSION The otolithic membrane is consistently damaged in patients with VDA. In addition, there is a significantly higher incidence of otolithic membrane injury in patients with MD and delayed EH compared with patients without hydrops, suggesting that the underlying pathophysiology in VDA results from injury to the otolithic membrane of the saccule and utricle, resulting in free-floating otoliths and atrophy.
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