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Baxi AB, Nemes P, Moody SA. Time-resolved quantitative proteomic analysis of the developing Xenopus otic vesicle reveals putative congenital hearing loss candidates. iScience 2023; 26:107665. [PMID: 37670778 PMCID: PMC10475516 DOI: 10.1016/j.isci.2023.107665] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 07/16/2023] [Accepted: 08/14/2023] [Indexed: 09/07/2023] Open
Abstract
Over 200 genes are known to underlie human congenital hearing loss (CHL). Although transcriptomic approaches have identified candidate regulators of otic development, little is known about the abundance of their protein products. We used a multiplexed quantitative mass spectrometry-based proteomic approach to determine protein abundances over key stages of Xenopus otic morphogenesis to reveal a dynamic expression of cytoskeletal, integrin signaling, and extracellular matrix proteins. We correlated these dynamically expressed proteins to previously published lists of putative downstream targets of human syndromic hearing loss genes: SIX1 (BOR syndrome), CHD7 (CHARGE syndrome), and SOX10 (Waardenburg syndrome). We identified transforming growth factor beta-induced (Tgfbi), an extracellular integrin-interacting protein, as a putative target of Six1 that is required for normal otic vesicle formation. Our findings demonstrate the application of this Xenopus dataset to understanding the dynamic regulation of proteins during otic development and to discovery of additional candidates for human CHL.
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Affiliation(s)
- Aparna B. Baxi
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC 20052, USA
| | - Peter Nemes
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Sally A. Moody
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, Washington, DC 20052, USA
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2
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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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3
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Armstrong PA, Wood SJ, Shimizu N, Kuster K, Perachio A, Makishima T. Preserved otolith organ function in caspase-3-deficient mice with impaired horizontal semicircular canal function. Exp Brain Res 2015; 233:1825-35. [PMID: 25827332 DOI: 10.1007/s00221-015-4254-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Accepted: 03/10/2015] [Indexed: 11/30/2022]
Abstract
Genetically engineered mice are valuable models for elucidation of auditory and vestibular pathology. Our goal was to establish a comprehensive vestibular function testing system in mice using: (1) horizontal angular vestibulo-ocular reflex (hVOR) to evaluate semicircular canal function and (2) otolith-ocular reflex (OOR) to evaluate otolith organ function and to validate the system by characterizing mice with vestibular dysfunction. We used pseudo off-vertical axis rotation to induce an otolith-only stimulus using a custom-made centrifuge. For the OOR, horizontal slow-phase eye velocity and vertical eye position were evaluated as a function of acceleration. Using this system, we characterized hVOR and OOR in the caspase-3 (Casp3) mutant mice. Casp3 (-/-) mice had severely impaired hVOR gain, while Casp3 (+/-) mice had an intermediate response compared to WT mice. Evaluation of OOR revealed that at low-to-mid frequencies and stimulus intensity, Casp3 mutants and WT mice had similar responses. At higher frequencies and stimulus intensity, the Casp3 mutants displayed mildly reduced otolith organ-related responses. These findings suggest that the Casp3 gene is important for the proper function of the semicircular canals but less important for the otolith organ function.
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Affiliation(s)
- Patrick A Armstrong
- Department of Otolaryngology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, 77555-0521, USA
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4
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Nakanishi H, Kurima K, Kawashima Y, Griffith AJ. Mutations of TMC1 cause deafness by disrupting mechanoelectrical transduction. Auris Nasus Larynx 2014; 41:399-408. [PMID: 24933710 DOI: 10.1016/j.anl.2014.04.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 04/22/2014] [Indexed: 01/05/2023]
Abstract
OBJECTIVE Mutations of transmembrane channel-like 1 gene (TMC1) can cause dominant (DFNA36) or recessive (DFNB7/B11) deafness. In this article, we describe the characteristics of DFNA36 and DFNB7/B11 deafness, the features of the Tmc1 mutant mouse strains, and recent advances in our understanding of TMC1 function. METHODS Publications related to TMC1, DFNA36, or DFNB7/B11 were identified through PubMed. RESULTS All affected DFNA36 subjects showed post-lingual, progressive, sensorineural hearing loss (HL), initially affecting high frequencies. In contrast, almost all affected DFNB7/B11 subjects demonstrated congenital or prelingual severe to profound sensorineural HL. The mouse Tmc1 gene also has dominant and recessive mutant alleles that cause HL in mutant strains, including Beethoven, deafness, and Tmc1 knockout mice. These mutant mice have been instrumental for revealing that Tmc1 and its closely related paralog Tmc2 are expressed in cochlear and vestibular hair cells, and are required for hair cell mechanoelectrical transduction (MET). Recent studies suggest that TMC1 and TMC2 may be components of the long-sought hair cell MET channel. CONCLUSION TMC1 mutations disrupt hair cell MET.
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Affiliation(s)
- Hiroshi Nakanishi
- Molecular Biology and Genetics Section, National Institute on Deafness and Other Communication Disorders (NIDCD), NIH, 35A Convent Dr, Bethesda, MD 20892, USA
| | - Kiyoto Kurima
- Molecular Biology and Genetics Section, National Institute on Deafness and Other Communication Disorders (NIDCD), NIH, 35A Convent Dr, Bethesda, MD 20892, USA
| | - Yoshiyuki Kawashima
- Department of Otolaryngology, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Andrew J Griffith
- Molecular Biology and Genetics Section, National Institute on Deafness and Other Communication Disorders (NIDCD), NIH, 35A Convent Dr, Bethesda, MD 20892, USA.
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5
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Miyasaka Y, Suzuki S, Ohshiba Y, Watanabe K, Sagara Y, Yasuda SP, Matsuoka K, Shitara H, Yonekawa H, Kominami R, Kikkawa Y. Compound heterozygosity of the functionally null Cdh23(v-ngt) and hypomorphic Cdh23(ahl) alleles leads to early-onset progressive hearing loss in mice. Exp Anim 2014; 62:333-46. [PMID: 24172198 PMCID: PMC4160959 DOI: 10.1538/expanim.62.333] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The waltzer (v) mouse mutant harbors a mutation in Cadherin 23
(Cdh23) and is a model for Usher syndrome type 1D, which is
characterized by congenital deafness, vestibular dysfunction, and prepubertal onset of
progressive retinitis pigmentosa. In mice, functionally null Cdh23
mutations affect stereociliary morphogenesis and the polarity of both cochlear and
vestibular hair cells. In contrast, the murine Cdh23ahl
allele, which harbors a hypomorphic mutation, causes an increase in susceptibility to
age-related hearing loss in many inbred strains. We produced congenic mice by crossing
mice carrying the v niigata (Cdh23v-ngt) null
allele with mice carrying the hypomorphic Cdh23ahl allele on
the C57BL/6J background, and we then analyzed the animals’ balance and hearing phenotypes.
Although the
Cdh23v-ngt/ahl
compound heterozygous mice exhibited normal vestibular function, their hearing ability was
abnormal: the mice exhibited higher thresholds of auditory brainstem response (ABR) and
rapid age-dependent elevation of ABR thresholds compared with
Cdh23ahl/ahl
homozygous mice. We found that the stereocilia developed normally but were progressively
disrupted in
Cdh23v-ngt/ahl mice.
In hair cells, CDH23 localizes to the tip links of stereocilia, which are thought to gate
the mechanoelectrical transduction channels in hair cells. We hypothesize that the
reduction of Cdh23 gene dosage in
Cdh23v-ngt/ahl mice
leads to the degeneration of stereocilia, which consequently reduces tip link tension.
These findings indicate that CDH23 plays an important role in the maintenance of tip links
during the aging process.
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Affiliation(s)
- Yuki Miyasaka
- Mammalian Genetics Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
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6
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Jamon M. The development of vestibular system and related functions in mammals: impact of gravity. Front Integr Neurosci 2014; 8:11. [PMID: 24570658 PMCID: PMC3916785 DOI: 10.3389/fnint.2014.00011] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 01/20/2014] [Indexed: 12/12/2022] Open
Abstract
This chapter reviews the knowledge about the adaptation to Earth gravity during the development of mammals. The impact of early exposure to altered gravity is evaluated at the level of the functions related to the vestibular system, including postural control, homeostatic regulation, and spatial memory. The hypothesis of critical periods in the adaptation to gravity is discussed. Demonstrating a critical period requires removing the gravity stimulus during delimited time windows, what is impossible to do on Earth surface. The surgical destruction of the vestibular apparatus, and the use of mice strains with defective graviceptors have provided useful information on the consequences of missing gravity perception, and the possible compensatory mechanisms, but transitory suppression of the stimulus can only be operated during spatial flight. The rare studies on rat pups housed on board of space shuttle significantly contributed to this problem, but the use of hypergravity environment, produced by means of chronic centrifugation, is the only available tool when repeated experiments must be carried out on Earth. Even though hypergravity is sometimes considered as a mirror situation to microgravity, the two situations cannot be confused because a gravitational force is still present. The theoretical considerations that validate the paradigm of hypergravity to evaluate critical periods are discussed. The question of adaption of graviceptor is questioned from an evolutionary point of view. It is possible that graviception is hardwired, because life on Earth has evolved under the constant pressure of gravity. The rapid acquisition of motor programming by precocial mammals in minutes after birth is consistent with this hypothesis, but the slow development of motor skills in altricial species and the plasticity of vestibular perception in adults suggest that gravity experience is required for the tuning of graviceptors. The possible reasons for this dichotomy are discussed.
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Affiliation(s)
- Marc Jamon
- Faculté de Médecine de la Timone, Institut National de la Santé et de la Recherche Médicale U 1106, Aix-Marseille University Marseille, France
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7
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Luo XJ, Deng M, Xie X, Huang L, Wang H, Jiang L, Liang G, Hu F, Tieu R, Chen R, Gan L. GATA3 controls the specification of prosensory domain and neuronal survival in the mouse cochlea. Hum Mol Genet 2013; 22:3609-23. [PMID: 23666531 DOI: 10.1093/hmg/ddt212] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
HDR syndrome (also known as Barakat syndrome) is a developmental disorder characterized by hypoparathyroidism, sensorineural deafness and renal disease. Although genetic mapping and subsequent functional studies indicate that GATA3 haplo-insufficiency causes human HDR syndrome, the role of Gata3 in sensorineural deafness and auditory system development is largely unknown. In this study, we show that Gata3 is continuously expressed in the developing mouse inner ear. Conditional knockout of Gata3 in the developing inner ear disrupts the morphogenesis of mouse inner ear, resulting in a disorganized and shortened cochlear duct with significant fewer hair cells and supporting cells. Loss of Gata3 function leads to the failure in the specification of prosensory domain and subsequently, to increased cell death in the cochlear duct. Moreover, though the initial generation of cochleovestibular ganglion (CVG) cells is not affected in Gata3-null mice, spiral ganglion neurons (SGNs) are nearly depleted due to apoptosis. Our results demonstrate the essential role of Gata3 in specifying the prosensory domain in the cochlea and in regulating the survival of SGNs, thus identifying a molecular mechanism underlying human HDR syndrome.
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Affiliation(s)
- Xiong-jian Luo
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, Zhejiang, China
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8
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Kikkawa Y, Seki Y, Okumura K, Ohshiba Y, Miyasaka Y, Suzuki S, Ozaki M, Matsuoka K, Noguchi Y, Yonekawa H. Advantages of a mouse model for human hearing impairment. Exp Anim 2012; 61:85-98. [PMID: 22531723 DOI: 10.1538/expanim.61.85] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Hearing is a major factor in human quality of life. Mouse models are important tools for discovering the genes that are responsible for genetic hearing loss, and these models often allow the processes that regulate the onset of deafness in humans to be analyzed. Thus far, in the study of hearing and deafness, at least 400 mutants with hearing impairments have been identified in laboratory mouse populations. Analysis of through a combination of genetic, morphological, and physiological studies is revealing valuable insights into the ontogenesis, morphogenesis, and function of the mammalian ear. This review discusses the advantages of the mouse models of human hearing impairment and highlights the identification of the molecules required for stereocilia development in the inner ear hair cells by analysis of various mouse mutants.
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Affiliation(s)
- Yoshiaki Kikkawa
- Mammalian Genetics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
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9
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Powers TR, Virk SM, Trujillo-Provencio C, Serrano EE. Probing the Xenopus laevis inner ear transcriptome for biological function. BMC Genomics 2012; 13:225. [PMID: 22676585 PMCID: PMC3532188 DOI: 10.1186/1471-2164-13-225] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 05/21/2012] [Indexed: 01/27/2023] Open
Abstract
Background The senses of hearing and balance depend upon mechanoreception, a process that originates in the inner ear and shares features across species. Amphibians have been widely used for physiological studies of mechanotransduction by sensory hair cells. In contrast, much less is known of the genetic basis of auditory and vestibular function in this class of animals. Among amphibians, the genus Xenopus is a well-characterized genetic and developmental model that offers unique opportunities for inner ear research because of the amphibian capacity for tissue and organ regeneration. For these reasons, we implemented a functional genomics approach as a means to undertake a large-scale analysis of the Xenopus laevis inner ear transcriptome through microarray analysis. Results Microarray analysis uncovered genes within the X. laevis inner ear transcriptome associated with inner ear function and impairment in other organisms, thereby supporting the inclusion of Xenopus in cross-species genetic studies of the inner ear. The use of gene categories (inner ear tissue; deafness; ion channels; ion transporters; transcription factors) facilitated the assignment of functional significance to probe set identifiers. We enhanced the biological relevance of our microarray data by using a variety of curation approaches to increase the annotation of the Affymetrix GeneChip® Xenopus laevis Genome array. In addition, annotation analysis revealed the prevalence of inner ear transcripts represented by probe set identifiers that lack functional characterization. Conclusions We identified an abundance of targets for genetic analysis of auditory and vestibular function. The orthologues to human genes with known inner ear function and the highly expressed transcripts that lack annotation are particularly interesting candidates for future analyses. We used informatics approaches to impart biologically relevant information to the Xenopus inner ear transcriptome, thereby addressing the impediment imposed by insufficient gene annotation. These findings heighten the relevance of Xenopus as a model organism for genetic investigations of inner ear organogenesis, morphogenesis, and regeneration.
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Affiliation(s)
- TuShun R Powers
- Biology Department, New Mexico State University, Las Cruces, USA
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10
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Somma G, Alger HM, McGuire RM, Kretlow JD, Ruiz FR, Yatsenko SA, Stankiewicz P, Harrison W, Funk E, Bergamaschi A, Oghalai JS, Mikos AG, Overbeek PA, Pereira FA. Head bobber: an insertional mutation causes inner ear defects, hyperactive circling, and deafness. J Assoc Res Otolaryngol 2012; 13:335-49. [PMID: 22383091 DOI: 10.1007/s10162-012-0316-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2010] [Accepted: 02/06/2012] [Indexed: 12/12/2022] Open
Abstract
The head bobber transgenic mouse line, produced by pronuclear integration, exhibits repetitive head tilting, circling behavior, and severe hearing loss. Transmitted as an autosomal recessive trait, the homozygote has vestibular and cochlea inner ear defects. The space between the semicircular canals is enclosed within the otic capsule creating a vacuous chamber with remnants of the semicircular canals, associated cristae, and vestibular organs. A poorly developed stria vascularis and endolymphatic duct is likely the cause for Reissner's membrane to collapse post-natally onto the organ of Corti in the cochlea. Molecular analyses identified a single integration of ~3 tandemly repeated copies of the transgene, a short duplicated segment of chromosome X and a 648 kb deletion of chromosome 7(F3). The three known genes (Gpr26, Cpxm2, and Chst15) in the deleted region are conserved in mammals and expressed in the wild-type inner ear during vestibular and cochlea development but are absent in homozygous mutant ears. We propose that genes critical for inner ear patterning and differentiation are lost at the head bobber locus and are candidate genes for human deafness and vestibular disorders.
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Affiliation(s)
- Giuseppina Somma
- Huffington Center on Aging, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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11
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Mutation of Rubie, a novel long non-coding RNA located upstream of Bmp4, causes vestibular malformation in mice. PLoS One 2012; 7:e29495. [PMID: 22253730 PMCID: PMC3257225 DOI: 10.1371/journal.pone.0029495] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 11/29/2011] [Indexed: 12/02/2022] Open
Abstract
Background The vestibular apparatus of the vertebrate inner ear uses three fluid-filled semicircular canals to sense angular acceleration of the head. Malformation of these canals disrupts the sense of balance and frequently causes circling behavior in mice. The Epistatic circler (Ecl) is a complex mutant derived from wildtype SWR/J and C57L/J mice. Ecl circling has been shown to result from the epistatic interaction of an SWR-derived locus on chromosome 14 and a C57L-derived locus on chromosome 4, but the causative genes have not been previously identified. Methodology/Principal Findings We developed a mouse chromosome substitution strain (CSS-14) that carries an SWR/J chromosome 14 on a C57BL/10J genetic background and, like Ecl, exhibits circling behavior due to lateral semicircular canal malformation. We utilized CSS-14 to identify the chromosome 14 Ecl gene by positional cloning. Our candidate interval is located upstream of bone morphogenetic protein 4 (Bmp4) and contains an inner ear-specific, long non-coding RNA that we have designated Rubie (RNA upstream of Bmp4 expressed in inner ear). Rubie is spliced and polyadenylated, and is expressed in developing semicircular canals. However, we discovered that the SWR/J allele of Rubie is disrupted by an intronic endogenous retrovirus that causes aberrant splicing and premature polyadenylation of the transcript. Rubie lies in the conserved gene desert upstream of Bmp4, within a region previously shown to be important for inner ear expression of Bmp4. We found that the expression patterns of Bmp4 and Rubie are nearly identical in developing inner ears. Conclusions/Significance Based on these results and previous studies showing that Bmp4 is essential for proper vestibular development, we propose that Rubie is the gene mutated in Ecl mice, that it is involved in regulating inner ear expression of Bmp4, and that aberrant Bmp4 expression contributes to the Ecl phenotype.
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12
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Dror AA, Brownstein Z, Avraham KB. Integration of human and mouse genetics reveals pendrin function in hearing and deafness. Cell Physiol Biochem 2011; 28:535-44. [PMID: 22116368 DOI: 10.1159/000335163] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2011] [Indexed: 12/21/2022] Open
Abstract
Genomic technology has completely changed the way in which we are able to diagnose human genetic mutations. Genomic techniques such as the polymerase chain reaction, linkage analysis, Sanger sequencing, and most recently, massively parallel sequencing, have allowed researchers and clinicians to identify mutations for patients with Pendred syndrome and DFNB4 non-syndromic hearing loss. While thus far most of the mutations have been in the SLC26A4 gene coding for the pendrin protein, other genetic mutations may contribute to these phenotypes as well. Furthermore, mouse models for deafness have been invaluable to help determine the mechanisms for SLC26A4-associated deafness. Further work in these areas of research will help define genotype-phenotype correlations and develop methods for therapy in the future.
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Affiliation(s)
- Amiel A Dror
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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13
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Makishima T, Hochman L, Armstrong P, Rosenberger E, Ridley R, Woo M, Perachio A, Wood S. Inner ear dysfunction in caspase-3 deficient mice. BMC Neurosci 2011; 12:102. [PMID: 21988729 PMCID: PMC3208590 DOI: 10.1186/1471-2202-12-102] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 10/12/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Caspase-3 is one of the most downstream enzymes activated in the apoptotic pathway. In caspase-3 deficient mice, loss of cochlear hair cells and spiral ganglion cells coincide closely with hearing loss. In contrast with the auditory system, details of the vestibular phenotype have not been characterized. Here we report the vestibular phenotype and inner ear anatomy in the caspase-3 deficient (Casp3(-/-)) mouse strain. RESULTS Average ABR thresholds of Casp3(-/-) mice were significantly elevated (P < 0.05) compared to Casp3(+/-) mice and Casp3(+/+) mice at 3 months of age. In DPOAE testing, distortion product 2F1-F2 was significantly decreased (P < 0.05) in Casp3(-/-) mice, whereas Casp3(+/-) and Casp3(+/+) mice showed normal and comparable values to each other. Casp3(-/-) mice were hyperactive and exhibited circling behavior when excited. In lateral canal VOR testing, Casp3(-/-) mice had minimal response to any of the stimuli tested, whereas Casp3(+/-) mice had an intermediate response compared to Casp3(+/+) mice. Inner ear anatomical and histological analysis revealed gross hypomorphism of the vestibular organs, in which the main site was the anterior semicircular canal. Hair cell numbers in the anterior- and lateral crista, and utricle were significantly smaller in Casp3(-/-) mice whereas the Casp3(+/-) and Casp3(+/+) mice had normal hair cell numbers. CONCLUSIONS These results indicate that caspase-3 is essential for correct functioning of the cochlea as well as normal development and function of the vestibule.
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Affiliation(s)
- Tomoko Makishima
- Department of Otolaryngology, University of Texas Medical Branch, Galveston, Texas, USA.
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14
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Chatterjee S, Kraus P, Lufkin T. A symphony of inner ear developmental control genes. BMC Genet 2010; 11:68. [PMID: 20637105 PMCID: PMC2915946 DOI: 10.1186/1471-2156-11-68] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Accepted: 07/16/2010] [Indexed: 01/21/2023] Open
Abstract
The inner ear is one of the most complex and detailed organs in the vertebrate body and provides us with the priceless ability to hear and perceive linear and angular acceleration (hence maintain balance). The development and morphogenesis of the inner ear from an ectodermal thickening into distinct auditory and vestibular components depends upon precise temporally and spatially coordinated gene expression patterns and well orchestrated signaling cascades within the otic vesicle and upon cellular movements and interactions with surrounding tissues. Gene loss of function analysis in mice has identified homeobox genes along with other transcription and secreted factors as crucial regulators of inner ear morphogenesis and development. While otic induction seems dependent upon fibroblast growth factors, morphogenesis of the otic vesicle into the distinct vestibular and auditory components appears to be clearly dependent upon the activities of a number of homeobox transcription factors. The Pax2 paired-homeobox gene is crucial for the specification of the ventral otic vesicle derived auditory structures and the Dlx5 and Dlx6 homeobox genes play a major role in specification of the dorsally derived vestibular structures. Some Micro RNAs have also been recently identified which play a crucial role in the inner ear formation.
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Affiliation(s)
- Sumantra Chatterjee
- Stem Cell and Developmental Biology, Genome Institute of Singapore, 60 Biopolis Street, 138672 Singapore
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15
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Mochizuki E, Okumura K, Ishikawa M, Yoshimoto S, Yamaguchi J, Seki Y, Wada K, Yokohama M, Ushiki T, Tokano H, Ishii R, Shitara H, Taya C, Kitamura K, Yonekawa H, Kikkawa Y. Phenotypic and expression analysis of a novel spontaneous myosin VI null mutant mouse. Exp Anim 2010; 59:57-71. [PMID: 20224170 DOI: 10.1538/expanim.59.57] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
In humans, hearing is a major factor in quality of life. Mouse models are important tools for the discovery of genes responsible for genetic hearing loss, often enabling analysis of the processes that regulate the onset of deafness in humans. Thus far, at least 400 deafness mutants have been discovered in laboratory mouse populations and used in the study of deafness. Here we report the discovery of a new spontaneous recessive Rinshoken shaker/waltzer (rsv) mutant derived from our in-house C57BL/6J stock, which exhibits circling and/or head-tossing behaviour and complete lack of auditory brain response to any sound pressure. The hearing and balance phenotypes are associated with structural defects, in particular, disorganisation and fusion of stereocilia in the inner ear hair cells. Two sets of intersubspecific N(2) mice were generated for the positional cloning of the rsv mutation. The mutant locus was mapped to a 4.8-Mb region of chromosome 9, which contains myosin VI (Myo6), a gene responsible for deafness in humans and Snell's waltzer mutation in mice. The rsv mutant showed reduced expressions of Myo6 mRNA and MYO6 protein in the inner ear. Moreover, no immunoreactivity was observed in the cochlear and vestibular hair cells in the rsv mutant mice. We sequenced the genomic region (30,154 bp) of Myo6, including all coding exons, a non-coding exon, UTRs and the Myo6 promoter; however, no mutation was discovered in these regions. We therefore speculate that loss of MYO6 expression might cause shaker/waltzer behaviour and deafness in the rsv mutant; also, loss of MYO6 expression might be the result of mutations in an unidentified regulatory region(s) of the gene.
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Affiliation(s)
- Eiji Mochizuki
- Department of Bioindustry, Tokyo University of Agriculture, Abashiri, Hokkaido, Japan
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Koo SK, Hill JK, Hwang CH, Lin ZS, Millen KJ, Wu DK. Lmx1a maintains proper neurogenic, sensory, and non-sensory domains in the mammalian inner ear. Dev Biol 2009; 333:14-25. [PMID: 19540218 PMCID: PMC3400700 DOI: 10.1016/j.ydbio.2009.06.016] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Revised: 06/10/2009] [Accepted: 06/11/2009] [Indexed: 12/24/2022]
Abstract
Lmx1a is a LIM homeodomain-containing transcription factor, which is required for the formation of multiple organs. Lmx1a is broadly expressed in early stages of the developing inner ear, but its expression is soon restricted to the non-sensory regions of the developing ear. In an Lmx1a functional null mutant, dreher (dr(J)/dr(J)), the inner ears lack a non-sensory structure, the endolymphatic duct, and the membranous labyrinth is poorly developed. These phenotypes are consistent with Lmx1a's role as a selector gene. More importantly, while all three primary fates of the inner ear - neural, sensory, and non-sensory - are specified in dr(J)/dr(J), normal boundaries among these tissues are often violated. For example, the neurogenic domain of the ear epithelium, from which cells delaminate to form the cochleovestibular ganglion, is expanded. Within the neurogenic domain, the demarcation between the vestibular and auditory neurogenic domains is most likely disrupted as well, based on the increased numbers of vestibular neuroblasts and ectopic expression of Fgf3, which normally is associated specifically with the vestibular neurogenic region. Furthermore, aberrant and ectopic sensory organs are observed; most striking among these is vestibular-like hair cells located in the cochlear duct.
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Affiliation(s)
- Soo Kyung Koo
- National Institute on Deafness and Other Communication Disorders, 5 Research Court, Rm 2B34, Rockville, Rockville, MD 20850, USA
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17
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Waryah AM, Rehman A, Ahmed ZM, Bashir ZH, Khan SY, Zafar AU, Riazuddin S, Friedman TB, Riazuddin S. DFNB74, a novel autosomal recessive nonsyndromic hearing impairment locus on chromosome 12q14.2-q15. Clin Genet 2009; 76:270-5. [PMID: 19650862 DOI: 10.1111/j.1399-0004.2009.01209.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Autosomal recessive nonsyndromic hearing impairment (ARNSHI) segregating in three unrelated, large consanguineous Pakistani families (PKDF528, PKDF859 and PKDF326) is linked to markers on chromosome 12q14.2-q15. This novel locus is designated DFNB74. Maximum two-point limit of detection (LOD) scores of 5.6, 5.7 and 2.6 were estimated for markers D12S313,D12S83 and D12S75 at theta = 0 for recessive deafness segregating in these three families. Haplotype analyses identified a critical linkage interval of 5.35 cM (5.36 Mb) defined by D12S329 at 74.58 cM and D12S313 at 79.93 cM. DFNB74 is the second ARNSHI locus mapped to chromosome 12, but the physical intervals do not overlap with one another. A locus contributing to the early onset, rapidly progressing hearing loss of A/J mice (ahl4, age-related hearing loss 4) was reported to map to chromosome 10 in a region of conserved synteny to DFNB74, suggesting that ahl4 and DFNB74 may be due to mutations of the same gene in these two species.
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Affiliation(s)
- A M Waryah
- National Centre of Excellence in Molecular Biology, Punjab University, Lahore 53700, Pakistan
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18
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Bosman EA, Quint E, Fuchs H, Hrabé de Angelis M, Steel KP. Catweasel mice: a novel role for Six1 in sensory patch development and a model for branchio-oto-renal syndrome. Dev Biol 2009; 328:285-96. [PMID: 19389353 PMCID: PMC2682643 DOI: 10.1016/j.ydbio.2009.01.030] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 01/20/2009] [Accepted: 01/22/2009] [Indexed: 11/18/2022]
Abstract
Large-scale mouse mutagenesis initiatives have provided new mouse mutants that are useful models of human deafness and vestibular dysfunction. Catweasel is a novel N-ethyl-N-nitrosourea (ENU)-induced mutation. Heterozygous catweasel mutant mice exhibit mild headtossing associated with a posterior crista defect. We mapped the catweasel mutation to a critical region of 13 Mb on chromosome 12 containing the Six1, -4 and -6 genes. We identified a basepair substitution in exon 1 of the Six1 gene that changes a conserved glutamic acid (E) at position 121 to a glycine (G) in the Six1 homeodomain. Cwe/Cwe animals lack Preyer and righting reflexes, display severe headshaking and have severely truncated cochlea and semicircular canals. Cwe/Cwe animals had very few hair cells in the utricle, but their ampullae and cochlea were devoid of any hair cells. Bmp4, Jag1 and Sox2 expression were largely absent at early stages of sensory development and NeuroD expression was reduced in the developing vestibulo-acoustic ganglion. Lastly we show that Six1 genetically interacts with Jag1. We propose that the catweasel phenotype is due to a hypomorphic mutation in Six1 and that catweasel mice are a suitable model for branchio-oto-renal syndrome. In addition Six1 has a pivotal role in early sensory patch development and may act in the same genetic pathway as Jag1.
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Affiliation(s)
- Erika A. Bosman
- The Wellcome Trust Sanger Institute, The Wellcome Trust Genome Campus, Hinxton CB10 1SA, UK
| | | | - Helmut Fuchs
- Helmholtz Zentrum München, GmbH, Ingolstädter Landstraβe 1, D-85764 Neuherberg, Germany
| | | | - Karen P. Steel
- The Wellcome Trust Sanger Institute, The Wellcome Trust Genome Campus, Hinxton CB10 1SA, UK
- Corresponding author. Fax: +44 1223 494840.
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Rotational responses of vestibular-nerve afferents innervating the semicircular canals in the C57BL/6 mouse. J Assoc Res Otolaryngol 2008; 9:334-48. [PMID: 18473139 DOI: 10.1007/s10162-008-0120-4] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Accepted: 03/28/2008] [Indexed: 01/07/2023] Open
Abstract
Extracellular recordings were made from vestibular-nerve afferents innervating the semicircular canals in anesthetized C57BL/6 mice ranging in age from 4-24 weeks. A normalized coefficient of variation was used to divide afferents into regular (CV*<0.1) and irregular (CV*>0.1) groups. There were three overall conclusions from this study. First, mouse afferents resemble those of other mammals in properties such as resting discharge rate and dependence of response dynamics on discharge regularity. Second, there are differences in mouse afferents relative to other mammals that are likely related to the smaller size of the semicircular canals. The rotational sensitivity of mouse afferents is approximately threefold lower than that reported for afferents in other mammals. One consequence of the lower sensitivity is that mouse afferents have a larger linear range for encoding head velocity. The long time constant of afferent discharge, which is a measure of low-frequency response dynamics, is shorter in mouse afferents than in other species. Third, juvenile mice (age 4-7 weeks) appear to lack a class of low-sensitivity, highly irregular afferents that are present in adult animals (age 10-24 weeks). By analogy to studies in the chinchilla, these irregular afferents with low sensitivities for lower rotational frequencies correspond to calyx-only afferents. These findings suggest that, although the calyx ending on to type I hair cells is morphologically complete in mice by the age of about 1 month, the physiological response properties in these juvenile animals are not equivalent to those in adults.
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20
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Abstract
BACKGROUND Gene therapy may provide a way to restore cochlear function to deaf patients. The most successful techniques for cochlear gene therapy have been injection of early-generation adenoviral vectors into scala media in guinea pigs. However, it is important to be able to perform gene therapy research in mice because there is wide availability of transgenic strains with hereditary hearing loss. PURPOSE We demonstrate our technique for delivery of a third-generation adenoviral vector, helper-dependent adenovirus (HDAd), to the adult mouse cochlea. METHODS Mice were injected with an HDAd that contained a reporter gene for either beta-galactosidase or green fluorescent protein into scala media. After 4 days, the cochleae were harvested for analyses. Auditory brainstem response monitoring of cochlear function was performed before making a cochleostomy, after making a cochleostomy, and before killing the animal. RESULTS Beta-galactosidase was identified in the spiral ligament, the organ of Corti, and spiral ganglion cells by light microscopy. Green fluorescent protein epifluorescence was assessed in whole-mount organ of Corti preparations using confocal microscopy. This demonstrated transduction of inner hair cells, outer hair cells, and supporting cells. Paraffin-embedded cross sections similarly revealed gene transduction within the organ of Corti. Threshold shifts of 39.8 +/- 5.4 and 37.7 +/- 5.5 dB were observed in mice injected with HDAd or control buffer, respectively. CONCLUSION The technique of scala media HDAd injection reliably infects the adult mouse cochlea, including cells within the organ of Corti, although the procedure itself adversely affects hearing.
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Sajan SA, Warchol ME, Lovett M. Toward a systems biology of mouse inner ear organogenesis: gene expression pathways, patterns and network analysis. Genetics 2007; 177:631-53. [PMID: 17660535 PMCID: PMC2013721 DOI: 10.1534/genetics.107.078584] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
We describe the most comprehensive study to date on gene expression during mouse inner ear (IE) organogenesis. Samples were microdissected from mouse embryos at E9-E15 in half-day intervals, a period that spans all of IE organogenesis. These included separate dissections of all discernible IE substructures such as the cochlea, utricle, and saccule. All samples were analyzed on high density expression microarrays under strict statistical filters. Extensive confirmatory tests were performed, including RNA in situ hybridizations. More than 5000 genes significantly varied in expression according to developmental stage, tissue, or both and defined 28 distinct expression patterns. For example, upregulation of 315 genes provided a clear-cut "signature" of early events in IE specification. Additional, clear-cut, gene expression signatures marked specific structures such as the cochlea, utricle, or saccule throughout late IE development. Pathway analysis identified 53 signaling cascades enriched within the 28 patterns. Many novel pathways, not previously implicated in IE development, including beta-adrenergic, amyloid, estrogen receptor, circadian rhythm, and immune system pathways, were identified. Finally, we identified positional candidate genes in 54 uncloned nonsyndromic human deafness intervals. This detailed analysis provides many new insights into the spatial and temporal genetic specification of this complex organ system.
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Affiliation(s)
- Samin A Sajan
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63310, USA
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22
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Sekiya T, Kojima K, Matsumoto M, Holley MC, Ito J. Rebuilding lost hearing using cell transplantation. Neurosurgery 2007; 60:417-33; discussion 433. [PMID: 17327786 DOI: 10.1227/01.neu.0000249189.46033.42] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVE The peripheral auditory nervous system (cochlea and auditory nerve) has a complex anatomy, and it has traditionally been thought that once the sensorineural structures are damaged, restoration of hearing is impossible. In the past decade, however, the potential to restore lost hearing has been intensively investigated using molecular and cell biological techniques, and we can now part with such a pessimistic view. In this review, we examine an important field in hearing restoration research: cell transplantation. METHODS Most efforts in this field have been directed to the replacement of hair cells by transplantation to the cochlea. Here, we focus on transplantation to the auditory nerve, from the side of the cerebellopontine angle rather than the cochlea. RESULTS Delivery of cells to the cochlea is potentially damaging, and nerve cells transplanted distally to the Schwann-glial transitional zone (cochlear side) may become inhibited when they reach the transitional zone. The auditory nerve is probably the most suitable route for cell transplantation. CONCLUSION The auditory nerve occupies an important position not only in neurosurgery but also in various diseases in other disciplines, and several lines of recent evidence indicate that it is a key target for hearing restoration. It is familiar to most neurosurgeons, and the recent advances in the molecular and cell biology of inner-ear development are of direct importance to neurorestorative medicine. In this article, we review the anatomy, development, and molecular biology of the auditory nerve and cochlea, with emphasis on the advances in cell transplantation.
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Affiliation(s)
- Tetsuji Sekiya
- Department of Otolaryngology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
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23
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Lilleväli K, Haugas M, Matilainen T, Pussinen C, Karis A, Salminen M. Gata3 is required for early morphogenesis and Fgf10 expression during otic development. Mech Dev 2006; 123:415-29. [PMID: 16806848 DOI: 10.1016/j.mod.2006.04.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Revised: 04/19/2006] [Accepted: 04/26/2006] [Indexed: 01/08/2023]
Abstract
Inner ear develops from an induced surface ectoderm placode that invaginates and closes to form the otic vesicle, which then undergoes a complex morphogenetic process to form the membranous labyrinth. Inner ear morphogenesis is severely affected in Gata3 deficient mouse embryos, but the onset and basis of the phenotype has not been known. We show here that Gata3 deficiency leads to severe and unique abnormalities during otic placode invagination. The invagination problems are accompanied often by the formation of a morphological boundary between the dorsal and ventral otic cup and by the precocious appearance of dorsal endolymphatic characteristics. In addition, the endolymphatic domain often detaches from the rest of the otic epithelium during epithelial closure. The expression of several cell adhesion mediating genes is altered in Gata3 deficient ears suggesting that Gata3 controls adhesion and morphogenetic movements in early otic epithelium. Inactivation of Gata3 leads also to a loss of Fgf10 expression in otic epithelium and auditory ganglion demonstrating that Gata3 is an important regulator of Fgf-signalling during otic development.
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Affiliation(s)
- Kersti Lilleväli
- Institute of Biotechnology, University of Helsinki, Viikinkaari 9, 00710 Helsinki, Finland
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24
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Calabrese DR, Hullar TE. Planar relationships of the semicircular canals in two strains of mice. J Assoc Res Otolaryngol 2006; 7:151-9. [PMID: 16718609 PMCID: PMC2504575 DOI: 10.1007/s10162-006-0031-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2005] [Accepted: 02/27/2006] [Indexed: 01/07/2023] Open
Abstract
The mouse is increasingly important as a subject of vestibular research. Although many studies have focused on the vestibular responses of mice to angular rotation, the geometry of their semicircular canals has not been described. High-voltage X-ray computed tomography was used to measure the anatomy of the semicircular canals of two strains of mice, C57Bl/6J and CBA/CaJ. The horizontal plane of a stereotaxic coordinate system was defined by the midpoints of the external auditory meati and the point where the incisors emerge from the maxilla. The centroids of the lumens of the bony canals were calculated, and planes that describe the canals were fit using a least-squares regression analysis to the resulting points. Vectors normal to each regressed plane were used to represent the corresponding canal's axis of rotation, and angles of these vectors relative to skull landmarks as well as to each other were calculated. The horizontal canal of the mouse was found to be angled anteriorly upward 17.8 degrees for CBA/CaJ and 32.6 degrees for C57Bl/6J from the reference horizontal plane. Angles between ipsilateral canals deviated up to 12.3 degrees from orthogonal, and angles between contralateral synergistic canals (left anterior-right posterior, right anterior-left posterior, and horizontal-horizontal) deviated from parallel by up to 14.8 degrees. The orientations of the canals within the head as well as the orientations of the canals relative to each other were significantly different between the two strains, suggesting that care must be taken in the design and interpretation of developmental and physiologic studies involving different mouse strains.
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Affiliation(s)
- Daniel R. Calabrese
- Department of Otolaryngology—Head and Neck Surgery, Washington University School of Medicine, 660 South Euclid Avenue #8115, Saint Louis, MO 63110 USA
| | - Timothy E. Hullar
- Department of Otolaryngology—Head and Neck Surgery, Washington University School of Medicine, 660 South Euclid Avenue #8115, Saint Louis, MO 63110 USA
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Shabbir MI, Ahmed ZM, Khan SY, Riazuddin S, Waryah AM, Khan SN, Camps RD, Ghosh M, Kabra M, Belyantseva IA, Friedman TB, Riazuddin S. Mutations of human TMHS cause recessively inherited non-syndromic hearing loss. J Med Genet 2006; 43:634-40. [PMID: 16459341 PMCID: PMC2564584 DOI: 10.1136/jmg.2005.039834] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Approximately half the cases of prelingual hearing loss are caused by genetic factors. Identification of genes causing deafness is a crucial first step in understanding the normal function of these genes in the auditory system. Recently, a mutant allele of Tmhs was reported to be associated with deafness and circling behaviour in the hurry-scurry mouse. Tmhs encodes a predicted tetraspan protein of unknown function, which is expressed in inner ear hair cells. The human homologue of Tmhs is located on chromosome 6p. OBJECTIVE To determine the cause of deafness in four consanguineous families segregating recessive deafness linked to markers on chromosome 6p21.1-p22.3 defining a novel DFNB locus. RESULTS A novel locus for non-syndromic deafness DFNB67 was mapped in an interval of approximately 28.51 cM on human chromosome 6p21.1-p22.3. DNA sequence analysis of TMHS revealed a homozygous frameshift mutation (246delC) and a missense mutation (Y127C) in affected individuals of two families segregating non-syndromic deafness, one of which showed significant evidence of linkage to markers in the DFNB67 interval. The localisation of mTMHS in developing mouse inner ear hair cells was refined and found to be expressed briefly from E16.5 to P3. CONCLUSIONS These findings establish the importance of TMHS for normal sound transduction in humans.
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Affiliation(s)
- M I Shabbir
- National Centre of Excellence in Molecular Biology, Punjab University, Thokar Niaz Baig, Lahore, Pakistan
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26
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Lilleväli K, Haugas M, Pituello F, Salminen M. Comparative analysis ofGata3 andGata2 expression during chicken inner ear development. Dev Dyn 2006; 236:306-13. [PMID: 17103399 DOI: 10.1002/dvdy.21011] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The inner ear is a complex sensory organ with hearing and balance functions. Gata3 and Gata2 are expressed in the inner ear, and to gain more insight into their roles in otic development, we made a detailed expression analysis in chicken embryos. At early stages, their expression was highly overlapping. At later stages, Gata2 expression became prominent in vestibular and cochlear nonsensory epithelia. In contrast to Gata2, Gata3 was mainly expressed in the developing sensory epithelia, reflecting the importance of this factor in the sensory-neural development of the inner ear. While the later expression patterns of both Gata3 and Gata2 were highly conserved between chicken and mouse, important differences were observed especially with Gata3 during early otic development, providing indications of divergent molecular control during placode invagination in mice and chickens. We also found indications that the regulatory hierarchy observed in mouse, where Gata3 is upstream of Gata2 and Fgf10, could be conserved in chicken.
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Affiliation(s)
- Kersti Lilleväli
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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27
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Lee HY, Camp AJ, Callister RJ, Brichta AM. Vestibular primary afferent activity in an in vitro preparation of the mouse inner ear. J Neurosci Methods 2005; 145:73-87. [PMID: 15922027 DOI: 10.1016/j.jneumeth.2004.11.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2004] [Revised: 11/22/2004] [Accepted: 11/22/2004] [Indexed: 10/26/2022]
Abstract
Most information on the properties of mammalian vestibular primary afferents has been obtained in deeply anesthetized animals, in vivo. Generally, non-human primates and larger rodents have been the species of choice. Investigations using smaller rodents, such as the laboratory mouse, have been limited despite the increasing availability of naturally occurring or engineered mutants that result in balance disorders. Furthermore, in vitro preparations of the intact peripheral vestibular apparatus are only available for non-mammalian vertebrates. To take advantage of the genetic/molecular advances available in mice and the utility of in vitro preparations that permit manipulations of the extracellular milieu, we developed an isolated mouse inner ear preparation with the attached eighth cranial nerve for electrophysiological recording. Intra-axonal recordings of background activity in vestibular primary afferents were obtained in a modified Ringer's solution (0.25 mM Ca2+; 3.25 mM Mg2+) at 22 degrees C. We also recorded afferent activity in the presence of neuroactive drugs known to affect various stages of the transduction cascade. These results, together with responses to sinusoidal mechanical deformation of the membranous ducts, showed that transduction mechanisms remain viable. Where possible, we also obtained results in vivo for comparison. In future, the in vitro mouse preparation will allow investigation of the effects of genetic manipulations and pharmacological agents on the intact peripheral vestibular apparatus.
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Affiliation(s)
- Heung-Youp Lee
- Department of Otolaryngology - HNS, The Catholic University of Korea, College of Medicine, Seoul, Korea
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28
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Abstract
The rate of identification of genes for hearing has clearly outpaced the rate of determination of the functions of these genes' products. The use of transgenic and knock-out mouse models is a powerful approach to the elucidation of gene function in the ear. A large number of gene-targeted mice with auditory defects have recently been created and characterized, and nine independent mouse lines in which Cre recombinase activity begins to be expressed during early embryonic development of the ear or is specifically expressed in hair cells during postnatal development will be useful for ear-specific gene manipulation when combined with mouse lines that have loxP sites flanking the genes of interest. Existing gene-trapped embryonic stem (ES) cells and existing targeting constructs are readily available; new targeting constructs can easily be created by modifying bacterial artificial chromosomes and using them to directly transfect and screen ES cells; and N-ethyl-N-nitrosourea mutagenesis of ES cells can create point mutations in specific genes. To minimize variation in hearing phenotypes and avoid undesired hearing defects, mutant mice in the common gene-targeting background strains (129 and C57BL/6) should be transferred into congenic CBA/CaJ, a strain with "gold standard" normal hearing. Valuable mutant strains can be maintained, distributed, and cryopreserved in one of four NIH-sponsored Mutant Mouse Regional Resource Centers. Targeting hearing genes in mice will provide unprecedented opportunities for collaboration and new directions in the hearing research community.
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Affiliation(s)
- Jiangang Gao
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105-2794, USA
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29
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Chang W, Brigande JV, Fekete DM, Wu DK. The development of semicircular canals in the inner ear: role of FGFs in sensory cristae. Development 2004; 131:4201-11. [PMID: 15280215 DOI: 10.1242/dev.01292] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the vertebrate inner ear, the ability to detect angular head movements lies in the three semicircular canals and their sensory tissues, the cristae. The molecular mechanisms underlying the formation of the three canals are largely unknown. Malformations of this vestibular apparatus found in zebrafish and mice usually involve both canals and cristae. Although there are examples of mutants with only defective canals, few mutants have normal canals without some prior sensory tissue specification, suggesting that the sensory tissues,cristae, might induce the formation of their non-sensory components, the semicircular canals. We fate-mapped the vertical canal pouch in chicken that gives rise to the anterior and posterior canals, using a fluorescent,lipophilic dye (DiI), and identified a canal genesis zone adjacent to each prospective crista that corresponds to the Bone morphogenetic protein 2 (Bmp2)-positive domain in the canal pouch. Using retroviruses or beads to increase Fibroblast Growth Factors (FGFs) for gain-of-function and beads soaked with the FGF inhibitor SU5402 for loss-of-function experiments,we show that FGFs in the crista promote canal development by upregulating Bmp2. We postulate that FGFs in the cristae induce a canal genesis zone by inducing/upregulating Bmp2 expression. Ectopic FGF treatments convert some of the cells in the canal pouch from the prospective common crus to a canal-like fate. Thus, we provide the first molecular evidence whereby sensory organs direct the development of the associated non-sensory components, the semicircular canals, in vertebrate inner ears.
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Affiliation(s)
- Weise Chang
- National Institute on Deafness and Other Communication Disorders, Rockville, MD 20850, USA
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Hardelin JP, Denoyelle F, Levilliers J, Simmler MC, Petit C. Les surdités héréditaires : génétique moléculaire. Med Sci (Paris) 2004; 20:311-6. [PMID: 15067576 DOI: 10.1051/medsci/2004203311] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This article outlines recent advances in explaining hereditary deafness in molecular terms, focusing on isolated (i.e. nonsyndromic) hearing loss. The number of genes identified (36 to date) is growing rapidly. However, difficulties inherent in genetic linkage analysis, coupled with the possible involvement of environmental causes, have so far prevented the characterization of the main genes causative or predisposing to the late-onset forms of deafness.
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Affiliation(s)
- Jean-Pierre Hardelin
- Unité de génétique des déficits sensoriels, Inserm U.587, Institut Pasteur, 25, rue du Docteur Roux, 75724 Paris Cedex 15, France
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Zhu M, Yang T, Wei S, DeWan AT, Morell RJ, Elfenbein JL, Fisher RA, Leal SM, Smith RJH, Friderici KH. Mutations in the gamma-actin gene (ACTG1) are associated with dominant progressive deafness (DFNA20/26). Am J Hum Genet 2003; 73:1082-91. [PMID: 13680526 PMCID: PMC1180488 DOI: 10.1086/379286] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2003] [Accepted: 08/14/2003] [Indexed: 12/11/2022] Open
Abstract
Age-related hearing loss (presbycusis) is a significant problem in the population. The genetic contribution to age-related hearing loss is estimated to be 40%-50%. Gene mutations that cause nonsyndromic progressive hearing loss with early onset may provide insight into the etiology of presbycusis. We have identified four families segregating an autosomal dominant, progressive, sensorineural hearing loss phenotype that has been linked to chromosome 17q25.3. The critical interval containing the causative gene was narrowed to approximately 2 million bp between markers D17S914 and D17S668. Cochlear-expressed genes were sequenced in affected family members. Sequence analysis of the gamma-actin gene (ACTG1) revealed missense mutations in highly conserved actin domains in all four families. These mutations change amino acids that are conserved in all actins, from protozoa to mammals, and were not found in >100 chromosomes from normal hearing individuals. Much of the specialized ultrastructural organization of the cells in the cochlea is based on the actin cytoskeleton. Many of the mutations known to cause either syndromic or nonsyndromic deafness occur in genes that interact with actin (e.g., the myosins, espin, and harmonin). The mutations we have identified are in various binding domains of actin and are predicted to mildly interfere with bundling, gelation, polymerization, or myosin movement and may cause hearing loss by hindering the repair or stability of cochlear cell structures damaged by noise or aging. This is the first description of a mutation in cytoskeletal, or nonmuscle, actin.
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Affiliation(s)
- M Zhu
- Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
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Abstract
The vertebrate inner ear is a marvel of structural and functional complexity, which is all the more remarkable because it develops from such a simple structure, the otic placode. Analysis of inner ear development has long been a fascination of experimental embryologists, who sought to understand cellular mechanisms of otic placode induction. More recently, however, molecular and genetic approaches have made the inner ear a useful model system for studying a much broader range of basic developmental mechanisms, including cell fate specification and differentiation, axial patterning, epithelial morphogenesis, cytoskeletal dynamics, stem cell biology, neurobiology, physiology, etc. Of course, there has also been tremendous progress in understanding the functions and processes peculiar to the inner ear. The goal of this review is to recount how historical approaches have shaped our understanding of the signaling interactions controlling early otic development; to discuss how new findings have led to fundamental new insights; and to point out new problems that need to be resolved in future research.
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Affiliation(s)
- Bruce B Riley
- Biology Department, Texas A&M University, College Station, TX 77843-3258, USA.
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Abstract
Given the unique biological requirements of sound transduction and the selective advantage conferred upon a species capable of sensitive sound detection, it is not surprising that up to 1% of the approximately 30,000 or more human genes are necessary for hearing. There are hundreds of monogenic disorders for which hearing loss is one manifestation of a syndrome or the only disorder and therefore is nonsyndromic. Herein we review the supporting evidence for identifying over 30 genes for dominantly and recessively inherited, nonsyndromic, sensorineural deafness. The state of knowledge concerning their biological roles is discussed in the context of the controversies within an evolving understanding of the intricate molecular machinery of the inner ear.
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Affiliation(s)
- Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, Maryland 20850, USA.
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Abstract
In the field of hearing research, recent advances using the mouse as a model for human hearing loss have brought exciting insights into the molecular pathways that lead to normal hearing, and into the mechanisms that are disrupted once a mutation occurs in one of the critical genes. Inaccessible for most procedures other than high-resolution computed tomography (CT) scanning or invasive surgery, most studies on the ear in humans can only be performed postmortem. A major goal in hearing research is to gain a full understanding of how a sound is heard at the molecular level, so that diagnostic and eventually therapeutic interventions can be developed that can treat the diseased inner ear before permanent damage has occurred, such as hair cell loss. The mouse, with its advantages of short gestation time, ease of selective matings, and similarity of the genome and inner ear to humans, is truly a remarkable resource for attaining this goal and investigating the intrigues of the human ear.
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Affiliation(s)
- Karen B Avraham
- Department of Human Genetics, Sackler School of Medicine, TelAviv University, Tel Aviv, Israel, USA.
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35
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Bober E, Rinkwitz S, Herbrand H. Molecular Basis of Otic Commitment and Morphogenesis: A Role for Homeodomain-Containing Transcription Factors and Signaling Molecules. Curr Top Dev Biol 2003; 57:151-75. [PMID: 14674480 DOI: 10.1016/s0070-2153(03)57005-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Eva Bober
- Institute of Physiological Chemistry, Martin-Luther University Halle-Wittenberg, Holly Strasse 1, D-06097, Halle, Germany
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