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Young CA, Burt E, Munnamalai V. A cochlear progenitor pool influences patterning of the mammalian sensory epithelium via MYBL2. Development 2024; 151:dev202635. [PMID: 39254648 PMCID: PMC11423912 DOI: 10.1242/dev.202635] [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: 12/18/2023] [Accepted: 08/01/2024] [Indexed: 09/11/2024]
Abstract
During embryonic development, Wnt signaling influences both proliferation and sensory formation in the cochlea. How this dual nature of Wnt signaling is coordinated is unknown. In this study, we define a novel role for a Wnt-regulated gene, Mybl2, which was already known to be important for proliferation, in determining the size and patterning of the sensory epithelium in the murine cochlea. Using a quantitative spatial analysis approach and analyzing Mybl2 loss-of-function, we show that Mybl2 promoted proliferation in the inner sulcus domain but limited the size of the sensory domain by influencing their adjoining boundary position via Jag1 regulation during development. Mybl2 loss-of-function simultaneously decreased proliferation in the inner sulcus and increased the size of the sensory domain, resulting in a wider sensory epithelium with ectopic inner hair cell formation during late embryonic stages. These data suggest that progenitor cells in the inner sulcus determine boundary formation and pattern the sensory epithelium via MYBL2.
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Affiliation(s)
- Caryl A. Young
- Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME 04469, USA
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Emily Burt
- Molecular Biosciences, The University of Kansas, Lawrence, KS 66045, USA
| | - Vidhya Munnamalai
- Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME 04469, USA
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
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2
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Beaulac HJ, Munnamalai V. Localization of cadherins in the postnatal cochlear epithelium and their relation to space formation. Dev Dyn 2024; 253:771-780. [PMID: 38264972 PMCID: PMC11266531 DOI: 10.1002/dvdy.692] [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: 10/23/2023] [Revised: 01/08/2024] [Accepted: 01/08/2024] [Indexed: 01/25/2024] Open
Abstract
The sensory epithelium of the cochlea, the organ of Corti, has complex cytoarchitecture consisting of mechanosensory hair cells intercalated by epithelial support cells. The support cells provide important trophic and structural support to the hair cells. Thus, the support cells must be stiff yet compliant enough to withstand and modulate vibrations to the hair cells. Once the sensory cells are properly patterned, the support cells undergo significant remodeling from a simple epithelium into a structurally rigid epithelium with fluid-filled spaces in the murine cochlea. Cell adhesion molecules such as cadherins are necessary for sorting and connecting cells in an intact epithelium. To create the fluid-filled spaces, cell adhesion properties of adjoining cell membranes between cells must change to allow the formation of spaces within an epithelium. However, the dynamic localization of cadherins has not been properly analyzed as these spaces are formed. There are three cadherins that are reported to be expressed during the first postnatal week of development when the tunnel of Corti forms in the cochlea. In this study, we characterize the dynamic localization of cadherins that are associated with cytoskeletal remodeling at the contacting membranes of the inner and outer pillar cells flanking the tunnel of Corti.
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3
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Beaulac HJ, Munnamalai V. Localization of Cadherins in the postnatal cochlear epithelium and their relation to space formation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.09.30.560287. [PMID: 37808730 PMCID: PMC10557783 DOI: 10.1101/2023.09.30.560287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
The sensory epithelium of the cochlea, the organ of Corti, has complex cytoarchitecture consisting of mechanosensory hair cells intercalated by epithelial support cells. The support cells provide important trophic and structural support to the hair cells. Thus, the support cells must be stiff yet compliant enough to withstand and modulate vibrations to the hair cells. Once the sensory cells are properly patterned, the support cells undergo significant remodeling from a simple epithelium into a structurally rigid epithelium with fluid-filled spaces in the murine cochlea. Cell adhesion molecules such as cadherins are necessary for sorting and connecting cells in an intact epithelium. To create the fluid-filled spaces, cell adhesion properties of adjoining cell membranes between cells must change to allow the formation of spaces within an epithelium. However, the dynamic localization of cadherins has not been properly analyzed as these spaces are formed. There are three cadherins that are reported to be expressed during the first postnatal week of development when the tunnel of Corti forms in the cochlea. In this study, we characterize the dynamic localization of cadherins that are associated with cytoskeletal remodeling at the contacting membranes of the inner and outer pillar cells flanking the tunnel of Corti. Key findings F-actin remodeling occurs between E18.5 to P7 in the cochlear sensory epithelium.Transient changes of F-actin cytoskeleton drives epithelial morphogenesis.Fluid-filled spaces in epithelium is driven by changes in cell adhesion.
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Young CA, Burt E, Munnamalai V. Sensory progenitors influence patterning of the mammalian auditory sensory epithelium. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.13.566920. [PMID: 38014307 PMCID: PMC10680690 DOI: 10.1101/2023.11.13.566920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
During embryonic development Wnt signaling has been shown to influence proliferation and sensory formation in the cochlea. How the dual nature of Wnt signaling is coordinated is unknown. In this study, we define a novel role for a Wnt regulated gene, Mybl2, which was already known to be important for proliferation, in influencing patterning and determining the size of the sensory epithelium in the murine cochlea. Using a quantitative spatial analysis approach and analyzing Mybl2 loss-of-function cochleas, we show that Mybl2 simultaneously specifies the progenitor niche and the size of the sensory domain, and influences the positioning of the medial sensory domain boundary via Jag1 regulation during the mid-gestational stages. Mybl2 conditional knockout resulted in a decrease of proliferation within the progenitor niche. During the late embryonic stages, conditional knockout of Mybl2 produced a wider sensory epithelium across the radial axis with an increase in ectopic inner hair cell formation. These data suggest that Mybl2 -positive progenitors play a role in boundary formation and patterning the sensory epithelium. Summary Statement Mybl2 is a Wnt-regulated gene encoding a transcription factor that is expressed in the cochlear progenitor niche and influences the boundary formation between the niche and the sensory domain during mid-cochlear developmental stages, thereby impacting the size of the sensory epithelium.
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Wang Y, Jin Y, Zhang Q, Xiong Y, Gu X, Zeng S, Chen W. Research progress in delineating the pathological mechanisms of GJB2-related hearing loss. Front Cell Neurosci 2023; 17:1208406. [PMID: 37333892 PMCID: PMC10272732 DOI: 10.3389/fncel.2023.1208406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 05/15/2023] [Indexed: 06/20/2023] Open
Abstract
Hearing loss is the most common congenital sensory impairment. Mutations or deficiencies of the GJB2 gene are the most common genetic cause of congenital non-syndromic deafness. Pathological changes such as decreased potential in the cochlea, active cochlear amplification disorders, cochlear developmental disorders and macrophage activation have been observed in various GJB2 transgenic mouse models. In the past, researchers generally believed that the pathological mechanisms underlying GJB2-related hearing loss comprised a K+ circulation defect and abnormal ATP-Ca2+ signals. However, recent studies have shown that K+ circulation is rarely associated with the pathological process of GJB2-related hearing loss, while cochlear developmental disorders and oxidative stress play an important, even critical, role in the occurrence of GJB2-related hearing loss. Nevertheless, these research has not been systematically summarized. In this review, we summarize the pathological mechanisms of GJB2-related hearing loss, including aspects of K+ circulation, developmental disorders of the organ of Corti, nutrition delivery, oxidative stress and ATP-Ca2+ signals. Clarifying the pathological mechanism of GJB2-related hearing loss can help develop new prevention and treatment strategies.
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Affiliation(s)
- Yujun Wang
- Department of Intensive Care Unit, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yuan Jin
- Department of Otorhinolaryngology–Head and Neck Surgery, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qiong Zhang
- Department of Otorhinolaryngology–Head and Neck Surgery, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ying Xiong
- Department of Otorhinolaryngology–Head and Neck Surgery, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiang Gu
- Department of Otorhinolaryngology–Head and Neck Surgery, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shan Zeng
- Department of Otorhinolaryngology–Head and Neck Surgery, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Chen
- Department of Otorhinolaryngology–Head and Neck Surgery, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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6
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Zhang H, Xie L, Chen S, Qiu Y, Sun Y, Kong W. Thyroxine Regulates the Opening of the Organ of Corti through Affecting P-Cadherin and Acetylated Microtubule. Int J Mol Sci 2022; 23:13339. [PMID: 36362134 PMCID: PMC9656988 DOI: 10.3390/ijms232113339] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 10/26/2022] [Accepted: 10/27/2022] [Indexed: 10/10/2023] Open
Abstract
Different serum thyroxine levels may influence the morphology of the inner ear during development. A well-developed organ of Corti (OC) is considered to be critical to the function of hearing. In our study, we treated mice with triiodothyronine (T3) and found that the opening of the OC occurred sooner than in control mice. We also observed an increased formation of acetylated microtubules and a decrease in the adhesion junction molecule P-cadherin the during opening of the OC. Our investigation indicates that thyroxin affects P-cadherin expression and microtubule acetylation to influence the opening of the OC.
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Affiliation(s)
- Huimin Zhang
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Le Xie
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
- Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Sen Chen
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
- Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yue Qiu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
- Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
- Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Weijia Kong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
- Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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7
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Cohen R, Sprinzak D. Mechanical forces shaping the development of the inner ear. Biophys J 2021; 120:4142-4148. [PMID: 34242589 DOI: 10.1016/j.bpj.2021.06.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/31/2021] [Accepted: 06/29/2021] [Indexed: 01/23/2023] Open
Abstract
The inner ear is one of the most complex structures in the mammalian body. Embedded within it are the hearing and balance sensory organs that contain arrays of hair cells that serve as sensors of sound and acceleration. Within the sensory organs, these hair cells are prototypically arranged in regular mosaic patterns. The development of such complex, yet precise, patterns require the coordination of differentiation, growth, and morphogenesis, both at the tissue and cellular scales. In recent years, there is accumulating evidence that mechanical forces at the tissue, the cellular, and the subcellular scales coordinate the development and organization of this remarkable organ. Here, we review recent works that reveal how such mechanical forces shape the inner ear, control its size, and establish regular cellular patterns. The insights learned from studying how mechanical forces drive the inner ear development are relevant for many other developmental systems in which precise cellular patterns are essential for their function.
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Affiliation(s)
- Roie Cohen
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel; Raymond and Beverly Sackler School of Physics and Astronomy, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel; The Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, Israel
| | - David Sprinzak
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel; The Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, Israel.
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8
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Defourny J. Eph/ephrin signalling in the development and function of the mammalian cochlea. Dev Biol 2019; 449:35-40. [PMID: 30771305 DOI: 10.1016/j.ydbio.2019.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 02/10/2019] [Accepted: 02/11/2019] [Indexed: 12/12/2022]
Abstract
In mammals, the functional development of the cochlea requires the tight regulation of multiple molecules and signalling pathways including fibroblast growth factors, bone morphogenetic proteins, Wnt and Notch signalling pathways. Over the last decade, the Eph/ephrin system also emerged as a key player of the development and function of the mammalian cochlea. In this review, we discuss the recent advances on the role of Eph/ephrin signalling in patterning the cochlear sensory epithelium and the complex innervation of mechanosensory hair cells by spiral ganglion neurons. Finally, we address the issue of a syndromic form of hearing loss caused by a deficient member of the Eph/ephrin family.
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Affiliation(s)
- Jean Defourny
- GIGA-Neurosciences, Unit of Cell and Tissue Biology, University of Liège, C.H.U. B36, B-4000, Liège, Belgium.
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9
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Defourny J, Peuckert C, Kullander K, Malgrange B. EphA4-ADAM10 Interplay Patterns the Cochlear Sensory Epithelium through Local Disruption of Adherens Junctions. iScience 2018; 11:246-257. [PMID: 30639848 PMCID: PMC6327856 DOI: 10.1016/j.isci.2018.12.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 12/19/2018] [Accepted: 12/20/2018] [Indexed: 12/11/2022] Open
Abstract
The cochlear sensory epithelium contains a functionally important triangular fluid-filled space between adjacent pillar cells referred to as the tunnel of Corti. However, the molecular mechanisms leading to local cell-cell separation during development remain elusive. Here we show that EphA4 associates with ADAM10 to promote the destruction of E-cadherin-based adhesions between adjacent pillar cells. These cells fail to separate from each other, and E-cadherin abnormally persists at the pillar cell junction in EphA4 forward-signaling-deficient mice, as well as in the presence of ADAM10 inhibitor. Using immunolabeling and an in situ proximity ligation assay, we found that EphA4 forms a complex with E-cadherin and its sheddase ADAM10, which could be activated by ephrin-B2 across the pillar cell junction to trigger the cleavage of E-cadherin. Altogether, our findings provide a new molecular insight into the regulation of adherens junctions, which might be extended to a variety of physiological or pathological processes.
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Affiliation(s)
- Jean Defourny
- GIGA-Neurosciences, Unit of Cell and Tissue Biology, University of Liège, C.H.U. B36, 4000 Liège, Belgium; GIGA-Neurosciences, Developmental Neurobiology Unit, University of Liège, C.H.U. B36, 4000 Liège, Belgium
| | - Christiane Peuckert
- Department of Neuroscience, Uppsala University, Box 593, Uppsala 75124, Sweden
| | - Klas Kullander
- Department of Neuroscience, Uppsala University, Box 593, Uppsala 75124, Sweden
| | - Brigitte Malgrange
- GIGA-Neurosciences, Developmental Neurobiology Unit, University of Liège, C.H.U. B36, 4000 Liège, Belgium.
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10
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Petitpré C, Wu H, Sharma A, Tokarska A, Fontanet P, Wang Y, Helmbacher F, Yackle K, Silberberg G, Hadjab S, Lallemend F. Neuronal heterogeneity and stereotyped connectivity in the auditory afferent system. Nat Commun 2018; 9:3691. [PMID: 30209249 PMCID: PMC6135759 DOI: 10.1038/s41467-018-06033-3] [Citation(s) in RCA: 148] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 07/31/2018] [Indexed: 01/07/2023] Open
Abstract
Spiral ganglion (SG) neurons of the cochlea convey all auditory inputs to the brain, yet the cellular and molecular complexity necessary to decode the various acoustic features in the SG has remained unresolved. Using single-cell RNA sequencing, we identify four types of SG neurons, including three novel subclasses of type I neurons and the type II neurons, and provide a comprehensive genetic framework that define their potential synaptic communication patterns. The connectivity patterns of the three subclasses of type I neurons with inner hair cells and their electrophysiological profiles suggest that they represent the intensity-coding properties of auditory afferents. Moreover, neuron type specification is already established at birth, indicating a neuronal diversification process independent of neuronal activity. Thus, this work provides a transcriptional catalog of neuron types in the cochlea, which serves as a valuable resource for dissecting cell-type-specific functions of dedicated afferents in auditory perception and in hearing disorders.
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Affiliation(s)
- Charles Petitpré
- Department of Neuroscience, Karolinska Institutet, Biomedicum, Stockholm, 171 77, Sweden
| | - Haohao Wu
- Department of Neuroscience, Karolinska Institutet, Biomedicum, Stockholm, 171 77, Sweden
| | - Anil Sharma
- Department of Neuroscience, Karolinska Institutet, Biomedicum, Stockholm, 171 77, Sweden
| | - Anna Tokarska
- Department of Neuroscience, Karolinska Institutet, Biomedicum, Stockholm, 171 77, Sweden
| | - Paula Fontanet
- Department of Neuroscience, Karolinska Institutet, Biomedicum, Stockholm, 171 77, Sweden
| | - Yiqiao Wang
- Department of Neuroscience, Karolinska Institutet, Biomedicum, Stockholm, 171 77, Sweden
| | - Françoise Helmbacher
- Aix-Marseille Université, CNRS UMR7288, Institut de Biologie du Développement de Marseille (IBDM), 13009, Marseille, France
| | - Kevin Yackle
- Department of Physiology, University of California-San Francisco, San Francisco, CA, 94158, USA
| | - Gilad Silberberg
- Department of Neuroscience, Karolinska Institutet, Biomedicum, Stockholm, 171 77, Sweden
| | - Saida Hadjab
- Department of Neuroscience, Karolinska Institutet, Biomedicum, Stockholm, 171 77, Sweden
| | - François Lallemend
- Department of Neuroscience, Karolinska Institutet, Biomedicum, Stockholm, 171 77, Sweden.
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11
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Wesdorp M, Murillo-Cuesta S, Peters T, Celaya AM, Oonk A, Schraders M, Oostrik J, Gomez-Rosas E, Beynon AJ, Hartel BP, Okkersen K, Koenen HJPM, Weeda J, Lelieveld S, Voermans NC, Joosten I, Hoyng CB, Lichtner P, Kunst HPM, Feenstra I, de Bruijn SE, Admiraal RJC, Yntema HG, van Wijk E, Del Castillo I, Serra P, Varela-Nieto I, Pennings RJE, Kremer H. MPZL2, Encoding the Epithelial Junctional Protein Myelin Protein Zero-like 2, Is Essential for Hearing in Man and Mouse. Am J Hum Genet 2018; 103:74-88. [PMID: 29961571 DOI: 10.1016/j.ajhg.2018.05.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 05/25/2018] [Indexed: 02/01/2023] Open
Abstract
In a Dutch consanguineous family with recessively inherited nonsyndromic hearing impairment (HI), homozygosity mapping combined with whole-exome sequencing revealed a MPZL2 homozygous truncating variant, c.72del (p.Ile24Metfs∗22). By screening a cohort of phenotype-matched subjects and a cohort of HI subjects in whom WES had been performed previously, we identified two additional families with biallelic truncating variants of MPZL2. Affected individuals demonstrated symmetric, progressive, mild to moderate sensorineural HI. Onset of HI was in the first decade, and high-frequency hearing was more severely affected. There was no vestibular involvement. MPZL2 encodes myelin protein zero-like 2, an adhesion molecule that mediates epithelial cell-cell interactions in several (developing) tissues. Involvement of MPZL2 in hearing was confirmed by audiometric evaluation of Mpzl2-mutant mice. These displayed early-onset progressive sensorineural HI that was more pronounced in the high frequencies. Histological analysis of adult mutant mice demonstrated an altered organization of outer hair cells and supporting cells and degeneration of the organ of Corti. In addition, we observed mild degeneration of spiral ganglion neurons, and this degeneration was most pronounced at the cochlear base. Although MPZL2 is known to function in cell adhesion in several tissues, no phenotypes other than HI were found to be associated with MPZL2 defects. This indicates that MPZL2 has a unique function in the inner ear. The present study suggests that deleterious variants of Mplz2/MPZL2 affect adhesion of the inner-ear epithelium and result in loss of structural integrity of the organ of Corti and progressive degeneration of hair cells, supporting cells, and spiral ganglion neurons.
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Affiliation(s)
- Mieke Wesdorp
- Hearing and Genes Division, Department of Otorhinolaryngology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; The Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Silvia Murillo-Cuesta
- Institute of Biomedical Research "Alberto Sols," Spanish National Research Council-Autonomous University of Madrid, 28029 Madrid, Spain; Center for Biomedical Network Research in Rare Diseases, Institute of Health Carlos III, 28029 Madrid, Spain; Hospital La Paz Institute for Health Research, 28029 Madrid, Spain
| | - Theo Peters
- Hearing and Genes Division, Department of Otorhinolaryngology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Adelaida M Celaya
- Institute of Biomedical Research "Alberto Sols," Spanish National Research Council-Autonomous University of Madrid, 28029 Madrid, Spain; Center for Biomedical Network Research in Rare Diseases, Institute of Health Carlos III, 28029 Madrid, Spain
| | - Anne Oonk
- Hearing and Genes Division, Department of Otorhinolaryngology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Margit Schraders
- Hearing and Genes Division, Department of Otorhinolaryngology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Jaap Oostrik
- Hearing and Genes Division, Department of Otorhinolaryngology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Elena Gomez-Rosas
- Center for Biomedical Network Research in Rare Diseases, Institute of Health Carlos III, 28029 Madrid, Spain; Servicio de Genetica, Hospital Universitario Ramon y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria, Madrid, Spain
| | - Andy J Beynon
- Hearing and Genes Division, Department of Otorhinolaryngology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Bas P Hartel
- Hearing and Genes Division, Department of Otorhinolaryngology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Kees Okkersen
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Department of Neurology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Hans J P M Koenen
- Laboratory of Medical Immunology, Department of Laboratory Medicine, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Jack Weeda
- Department of Ophthalmology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Stefan Lelieveld
- The Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Department of Human Genetics, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Nicol C Voermans
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Department of Neurology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Irma Joosten
- Laboratory of Medical Immunology, Department of Laboratory Medicine, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Carel B Hoyng
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Department of Ophthalmology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Peter Lichtner
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Henricus P M Kunst
- Hearing and Genes Division, Department of Otorhinolaryngology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Radboud Institute of Health Sciences, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Ilse Feenstra
- Department of Human Genetics, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Suzanne E de Bruijn
- Department of Human Genetics, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Ronald J C Admiraal
- Hearing and Genes Division, Department of Otorhinolaryngology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Helger G Yntema
- Department of Human Genetics, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Erwin van Wijk
- Hearing and Genes Division, Department of Otorhinolaryngology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Ignacio Del Castillo
- Center for Biomedical Network Research in Rare Diseases, Institute of Health Carlos III, 28029 Madrid, Spain; Servicio de Genetica, Hospital Universitario Ramon y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria, Madrid, Spain
| | - Pau Serra
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Isabel Varela-Nieto
- Institute of Biomedical Research "Alberto Sols," Spanish National Research Council-Autonomous University of Madrid, 28029 Madrid, Spain; Center for Biomedical Network Research in Rare Diseases, Institute of Health Carlos III, 28029 Madrid, Spain; Hospital La Paz Institute for Health Research, 28029 Madrid, Spain
| | - Ronald J E Pennings
- Hearing and Genes Division, Department of Otorhinolaryngology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Hannie Kremer
- Hearing and Genes Division, Department of Otorhinolaryngology, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Department of Human Genetics, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands.
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12
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Zhang J, Sun H, Salvi R, Ding D. Paraquat initially damages cochlear support cells leading to anoikis-like hair cell death. Hear Res 2018; 364:129-141. [PMID: 29563067 PMCID: PMC5984146 DOI: 10.1016/j.heares.2018.03.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 02/20/2018] [Accepted: 03/09/2018] [Indexed: 12/11/2022]
Abstract
Paraquat (PQ), one of the most widely used herbicides, is extremely dangerous because it generates the highly toxic superoxide radical. When paraquat was applied to cochlear organotypic cultures, it not only damaged the outer hair cells (OHCs) and inner hair cells (IHCs), but also caused dislocation of the hair cell rows. We hypothesized that the dislocation arose from damage to the support cells (SCs) that anchors hair cells within the epithelium. To test this hypothesis, rat postnatal cochlear cultures were treated with PQ. Shortly after PQ treatment, the rows of OHCs separated from one another and migrated radially away from IHCs suggesting loss of cell-cell adhesion that hold the hair cells in proper alignment. Hair cells dislocation was associated with extensive loss of SCs in the organ of Corti, loss of tympanic border cells (TBCs) beneath the basilar membrane, the early appearance of superoxide staining and caspase-8 labeling in SCs below the OHCs and disintegration of E-cadherin and β-catenin in the organ of Corti. Damage to the TBCs and SCs occurred prior to loss of OHC or IHC loss suggesting a form of detachment-induced apoptosis referred to as anoikis.
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Affiliation(s)
- Jianhui Zhang
- Department of Otorhinolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, China; Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, 14214, USA
| | - Hong Sun
- Department of Otorhinolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, China; Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, 14214, USA
| | - Richard Salvi
- Department of Otorhinolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, China; Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, 14214, USA; Department of Audiology and Speech-Language Pathology, Asia University, Taichung, Taiwan, ROC
| | - Dalian Ding
- Department of Otorhinolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, China; Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, 14214, USA.
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13
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Song YL, Tian KY, Mi WJ, Ding ZJ, Qiu Y, Chen FQ, Zha DJ, Qiu JH. Decreased expression of TERT correlated with postnatal cochlear development and proliferation reduction of cochlear progenitor cells. Mol Med Rep 2018; 17:6077-6083. [PMID: 29436610 DOI: 10.3892/mmr.2018.8565] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Accepted: 01/17/2018] [Indexed: 11/06/2022] Open
Abstract
Cochlear progenitor cells are considered as one of the best candidates for hair cell regeneration, thus, the regulation of cochlear progenitor cell proliferation has become a focus in this field. Several genes expressed in the inner ear during postnatal development have been demonstrated to be involved in maintaining the proliferative potential of progenitor cells, but the mechanism for regulating the proliferation and differentiation of cochlear progenitor cells remains poorly understood. Telomerase reverse transcriptase (TERT) has rate limiting telomerase activity and the overexpression of TERT has been shown to promote cell proliferation in series of cell lines. The aim of the present study was to evaluate the expression of TERT in the postnatal development of the cochlea and progenitor cells. The results demonstrated that TERT was expressed in the basilar membranes during the first postnatal week. In vitro, TERT expression in progenitor cells reached a maximum at day 4 after culture and decreased as the culture time prolonged or the cell passage number increased. These results led us to hypothesize that TERT may be involved in the development of the cochlea and in maintaining the proliferation ability of progenitor cells.
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Affiliation(s)
- Yong-Li Song
- Department of Otolaryngology‑Head and Neck Surgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi 710032, P.R. China
| | - Ke-Yong Tian
- Department of Otolaryngology‑Head and Neck Surgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi 710032, P.R. China
| | - Wen-Juan Mi
- Department of Otolaryngology‑Head and Neck Surgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi 710032, P.R. China
| | - Zhong-Jia Ding
- Department of Otolaryngology‑Head and Neck Surgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi 710032, P.R. China
| | - Yang Qiu
- Department of Otolaryngology‑Head and Neck Surgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi 710032, P.R. China
| | - Fu-Quan Chen
- Department of Otolaryngology‑Head and Neck Surgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi 710032, P.R. China
| | - Ding-Jun Zha
- Department of Otolaryngology‑Head and Neck Surgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi 710032, P.R. China
| | - Jian-Hua Qiu
- Department of Otolaryngology‑Head and Neck Surgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi 710032, P.R. China
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14
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Ladrech S, Eybalin M, Puel JL, Lenoir M. Epithelial-mesenchymal transition, and collective and individual cell migration regulate epithelial changes in the amikacin-damaged organ of Corti. Histochem Cell Biol 2017; 148:129-142. [PMID: 28365859 DOI: 10.1007/s00418-017-1548-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2017] [Indexed: 12/23/2022]
Abstract
Characterizing the microenvironment of a damaged organ of Corti and identifying the basic mechanisms involved in subsequent epithelial reorganization are critical for improving the outcome of clinical therapies. In this context, we studied the expression of a variety of cell markers related to cell shape, cell adhesion and cell plasticity in the rat organ of Corti poisoned with amikacin. Our results indicate that, after severe outer hair cell losses, the cytoarchitectural reorganization of the organ of Corti implicates epithelial-mesenchymal transition mechanisms and involves both collective and individual cell migratory processes. The results also suggest that both root cells and infiltrated fibroblasts participate in the homeostasis of the damaged epithelium, and that the flat epithelium that may emerge offers biological opportunities for late regenerative therapies.
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Affiliation(s)
- Sabine Ladrech
- INSERM U1051, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, 80 rue Augustin Fliche, 34091, Montpellier Cedex 5, France.,University of Montpellier, Montpellier, France
| | - Michel Eybalin
- INSERM U1051, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, 80 rue Augustin Fliche, 34091, Montpellier Cedex 5, France.,University of Montpellier, Montpellier, France
| | - Jean-Luc Puel
- INSERM U1051, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, 80 rue Augustin Fliche, 34091, Montpellier Cedex 5, France.,University of Montpellier, Montpellier, France
| | - Marc Lenoir
- INSERM U1051, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, 80 rue Augustin Fliche, 34091, Montpellier Cedex 5, France. .,University of Montpellier, Montpellier, France.
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15
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Togashi H. Differential and Cooperative Cell Adhesion Regulates Cellular Pattern in Sensory Epithelia. Front Cell Dev Biol 2016; 4:104. [PMID: 27695692 PMCID: PMC5023662 DOI: 10.3389/fcell.2016.00104] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 08/31/2016] [Indexed: 11/13/2022] Open
Abstract
Animal tissues are composed of multiple cell types arranged in complex and elaborate patterns. In sensory epithelia, including the auditory epithelium and olfactory epithelium, different types of cells are arranged in unique mosaic patterns. These mosaic patterns are evolutionarily conserved, and are thought to be important for hearing and olfaction. Recent progress has provided accumulating evidence that the cellular pattern formation in epithelia involves cell rearrangements, movements, and shape changes. These morphogenetic processes are largely mediated by intercellular adhesion systems. Differential adhesion and cortical tension have been proposed to promote cell rearrangements. Many different types of cells in tissues express various types of cell adhesion molecules. Although cooperative mechanisms between multiple adhesive systems are likely to contribute to the production of complex cell patterns, our current understanding of the cooperative roles between multiple adhesion systems is insufficient to entirely explain the complex mechanisms underlying cellular patterning. Recent studies have revealed that nectins, in cooperation with cadherins, are crucial for the mosaic cellular patterning in sensory organs. The nectin and cadherin systems are interacted with one another, and these interactions provide cells with differential adhesive affinities for complex cellular pattern formations in sensory epithelia, which cannot be achieved by a single mechanism.
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Affiliation(s)
- Hideru Togashi
- Division of Molecular and Cellular Biology, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine Kobe, Japan
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16
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Katsunuma S, Honda H, Shinoda T, Ishimoto Y, Miyata T, Kiyonari H, Abe T, Nibu KI, Takai Y, Togashi H. Synergistic action of nectins and cadherins generates the mosaic cellular pattern of the olfactory epithelium. J Cell Biol 2016; 212:561-75. [PMID: 26929452 PMCID: PMC4772500 DOI: 10.1083/jcb.201509020] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Cellular rearrangements between olfactory cells and supporting cells, driven by the different expression and distribution of nectins and cadherins, are required for mosaic cellular patterning in the olfactory epithelium. In the olfactory epithelium (OE), olfactory cells (OCs) and supporting cells (SCs), which express different cadherins, are arranged in a characteristic mosaic pattern in which OCs are enclosed by SCs. However, the mechanism underlying this cellular patterning is unclear. Here, we show that the cellular pattern of the OE is established by cellular rearrangements during development. In the OE, OCs express nectin-2 and N-cadherin, and SCs express nectin-2, nectin-3, E-cadherin, and N-cadherin. Heterophilic trans-interaction between nectin-2 on OCs and nectin-3 on SCs preferentially recruits cadherin via α-catenin to heterotypic junctions, and the differential distributions of cadherins between junctions promote cellular intercalations, resulting in the formation of the mosaic pattern. These observations are confirmed by model cell systems, and various cellular patterns are generated by the combinatorial expression of nectins and cadherins. Collectively, the synergistic action of nectins and cadherins generates mosaic pattern, which cannot be achieved by a single mechanism.
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Affiliation(s)
- Sayaka Katsunuma
- Division of Molecular and Cellular Biology, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Hisao Honda
- Division of Neural Differentiation and Regeneration, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan Laboratory for Morphogenetic Signaling, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan
| | - Tomoyasu Shinoda
- Department of Anatomy and Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Yukitaka Ishimoto
- Department of Machine Intelligence and Systems Engineering, Akita Prefectural University, Akita 015-0055, Japan
| | - Takaki Miyata
- Department of Anatomy and Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Hiroshi Kiyonari
- Animal Resource Development Unit, RIKEN Center for Life Science Technologies, Kobe 650-0047, Japan Genetic Engineering Team, Division of Bio-function Dynamics Imaging, RIKEN Center for Life Science Technologies, Kobe 650-0047, Japan
| | - Takaya Abe
- Genetic Engineering Team, Division of Bio-function Dynamics Imaging, RIKEN Center for Life Science Technologies, Kobe 650-0047, Japan
| | - Ken-Ichi Nibu
- Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Yoshimi Takai
- Division of Molecular and Cellular Biology, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0047, Japan CREST, Japan Science and Technology Agency, Kobe 650-0047, Japan
| | - Hideru Togashi
- Division of Molecular and Cellular Biology, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
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17
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Li W, You D, Chen Y, Chai R, Li H. Regeneration of hair cells in the mammalian vestibular system. Front Med 2016; 10:143-51. [DOI: 10.1007/s11684-016-0451-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 04/11/2016] [Indexed: 11/25/2022]
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18
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Wang B, Hu B, Yang S. Cell junction proteins within the cochlea: A review of recent research. J Otol 2016; 10:131-135. [PMID: 29937796 PMCID: PMC6002592 DOI: 10.1016/j.joto.2016.01.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 01/14/2016] [Accepted: 01/14/2016] [Indexed: 01/29/2023] Open
Abstract
Cell–cell junctions in the cochlea are highly complex and well organized. The role of these junctions is to maintain structural and functional integrity of the cochlea. In this review, we describe classification of cell junction-associated proteins identified within the cochlea and provide a brief overview of the function of these proteins in adherent junctions, gap junctions and tight junctions.
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Affiliation(s)
- Bo Wang
- Department of Otolaryngology Head & Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing, 100853, PR China.,Astronaut Research and Training Center of China, 26 Beiqing Road, Beijing, 10094, PR China.,Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY, 14214, USA
| | - Bohua Hu
- Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY, 14214, USA
| | - Shiming Yang
- Department of Otolaryngology Head & Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing, 100853, PR China
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19
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Fujita T, Yamashita D, Irino Y, Kitamoto J, Fukuda Y, Inokuchi G, Hasegawa S, Otsuki N, Yoshida M, Nibu KI. Metabolomic profiling in inner ear fluid by gas chromatography/mass spectrometry in guinea pig cochlea. Neurosci Lett 2015; 606:188-93. [PMID: 26343935 DOI: 10.1016/j.neulet.2015.09.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 08/12/2015] [Accepted: 09/01/2015] [Indexed: 01/10/2023]
Abstract
The composition and homeostasis of inner ear fluids are important in hearing function. The purpose of this study was to perform metabolomic analysis of the inner ear fluid in guinea pig cochlea, which has not been previously reported in literature, using gas chromatography/mass spectrometry (GC/MS). Seventy-seven kinds of metabolites were detected in the inner ear fluid. Six metabolites, ascorbic acid, fructose, galactosamine, inositol, pyruvate+oxaloacetic acid, and meso-erythritol, were significantly more abundant, and nine metabolites, phosphate, valine, glycine, glycerol, ornithine, glucose, citric acid+isocitric acid, mannose, and trans-4-hydroxy-L-proline, were less abundant in the inner ear fluid than in plasma. The levels of ten metabolites, 3-hydroxy-butyrate, glycerol, fumaric acid, galactosamine, pyruvate+oxaloacetic acid, phosphate, meso-erythritol, citric acid+isocitric acid, mannose, and inositol, in the inner ear fluid significantly changed after loud noise exposure. These observations may help to elucidate various clinical conditions of sensorineural hearing loss, including noise-induced hearing loss.
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Affiliation(s)
- Takeshi Fujita
- Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
| | - Daisuke Yamashita
- Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan.
| | - Yasuhiro Irino
- The Integrated Center for Mass Spectrometry, Graduate School of Medicine, Kobe University, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
| | - Junko Kitamoto
- Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
| | - Yuriko Fukuda
- Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
| | - Go Inokuchi
- Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
| | - Shingo Hasegawa
- Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
| | - Naoki Otsuki
- Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
| | - Masaru Yoshida
- The Integrated Center for Mass Spectrometry, Graduate School of Medicine, Kobe University, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan; Division of Metabolomics Research, Graduate School of Medicine, Kobe University, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
| | - Ken-ichi Nibu
- Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
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20
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Cai Q, Wang B, Coling D, Zuo J, Fang J, Yang S, Vera K, Hu BH. Reduction in noise-induced functional loss of the cochleae in mice with pre-existing cochlear dysfunction due to genetic interference of prestin. PLoS One 2014; 9:e113990. [PMID: 25486270 PMCID: PMC4259315 DOI: 10.1371/journal.pone.0113990] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 11/02/2014] [Indexed: 11/18/2022] Open
Abstract
Various cochlear pathologies, such as acoustic trauma, ototoxicity and age-related degeneration, cause hearing loss. These pre-existing hearing losses can alter cochlear responses to subsequent acoustic overstimulation. So far, the knowledge on the impacts of pre-existing hearing loss caused by genetic alteration of cochlear genes is limited. Prestin is the motor protein expressed exclusively in outer hair cells in the mammalian cochlea. This motor protein contributes to outer hair cell motility. At present, it is not clear how the interference of prestin function affects cochlear responses to acoustic overstimulation. To address this question, a genetic model of prestin dysfunction in mice was created by inserting an internal ribosome entry site (IRES)-CreERT2-FRT-Neo-FRT cassette into the prestin locus after the stop codon. Homozygous mice exhibit a threshold elevation of auditory brainstem responses with large individual variation. These mice also display a threshold elevation and a shift of the input/output function of the distortion product otoacoustic emission, suggesting a reduction in outer hair cell function. The disruption of prestin function reduces the threshold shifts caused by exposure to a loud noise at 120 dB (sound pressure level) for 1 h. This reduction is positively correlated with the level of pre-noise cochlear dysfunction and is accompanied by a reduced change in Cdh1 expression, suggesting a reduction in molecular responses to the acoustic overstimulation. Together, these results suggest that prestin interference reduces cochlear stress responses to acoustic overstimulation.
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Affiliation(s)
- Qunfeng Cai
- Center for Hearing and Deafness, University at Buffalo, Buffalo, New York, United States of America
| | - Bo Wang
- Department of Otolaryngology and Head & Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, China
| | - Donald Coling
- Center for Hearing and Deafness, University at Buffalo, Buffalo, New York, United States of America
| | - Jian Zuo
- Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America
| | - Jie Fang
- Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America
| | - Shiming Yang
- Department of Otolaryngology and Head & Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, China
| | - Krystal Vera
- Center for Hearing and Deafness, University at Buffalo, Buffalo, New York, United States of America
| | - Bo Hua Hu
- Center for Hearing and Deafness, University at Buffalo, Buffalo, New York, United States of America
- * E-mail:
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21
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Abstract
The development of hair cells in the auditory system can be separated into steps; first, the establishment of progenitors for the sensory epithelium, and second, the differentiation of hair cells. Although the differentiation of hair cells is known to require the expression of basic helix-loop-helix transcription factor, Atoh1, the control of cell proliferation in the region of the developing cochlea that will ultimately become the sensory epithelium and the cues that initiate Atoh1 expression remain obscure. We assessed the role of Wnt/β-catenin in both steps in gain- and loss-of-function models in mice. The canonical Wnt pathway mediator, β-catenin, controls the expression of Atoh1. Knock-out of β-catenin inhibited hair-cell, as well as pillar-cell, differentiation from sensory progenitors but was not required to maintain a hair-cell fate once specified. Constitutive activation of β-catenin expanded sensory progenitors by inducing additional cell division and resulted in the differentiation of extra hair cells. Our data demonstrate that β-catenin plays a role in cell division and differentiation in the cochlear sensory epithelium.
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22
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Burns JC, Collado MS, Oliver ER, Corwin JT. Specializations of intercellular junctions are associated with the presence and absence of hair cell regeneration in ears from six vertebrate classes. J Comp Neurol 2013; 521:1430-48. [PMID: 23124808 DOI: 10.1002/cne.23250] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 10/10/2012] [Accepted: 10/25/2012] [Indexed: 01/12/2023]
Abstract
Sensory hair cell losses lead to hearing and balance deficits that are permanent for mammals, but temporary for nonmammals because supporting cells in their ears give rise to replacement hair cells. In mice and humans, vestibular supporting cells grow exceptionally large circumferential F-actin belts and their junctions express E-cadherin in patterns that strongly correlate with postnatal declines in regeneration capacity. In contrast, chicken supporting cells retain thin F-actin belts throughout life and express little E-cadherin. To determine whether the junctions in chicken ears might be representative of other ears that also regenerate hair cells, we investigated inner ears from dogfish sharks, zebrafish, bullfrogs, Xenopus, turtles, and the lizard, Anolis. As in chickens, the supporting cells in adult zebrafish, Xenopus, and turtle ears retained thin circumferential F-actin belts and expressed little E-cadherin. Supporting cells in adult sharks and bullfrogs also retained thin belts, but were not tested for E-cadherin. Supporting cells in adult Anolis exhibited wide, but porous webs of F-actin and strong E-cadherin expression. Anolis supporting cells also showed some cell cycle reentry when cultured. The results reveal that the association between thin F-actin belts and low E-cadherin is shared by supporting cells in anamniotes, turtles, and birds, which all can regenerate hair cells. Divergent junctional specializations in supporting cells appear to have arisen independently in Anolis and mammals. The presence of webs of F-actin at the junctions in Anolis appears compatible with supporting cell proliferation, but the solid reinforcement of the F-actin belts in mammals is associated with its absence.
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Affiliation(s)
- Joseph C Burns
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
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23
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Postnatal development, maturation and aging in the mouse cochlea and their effects on hair cell regeneration. Hear Res 2012; 297:68-83. [PMID: 23164734 DOI: 10.1016/j.heares.2012.11.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 10/22/2012] [Accepted: 11/07/2012] [Indexed: 12/23/2022]
Abstract
The organ of Corti in the mammalian inner ear is comprised of mechanosensory hair cells (HCs) and nonsensory supporting cells (SCs), both of which are believed to be terminally post-mitotic beyond late embryonic ages. Consequently, regeneration of HCs and SCs does not occur naturally in the adult mammalian cochlea, though recent evidence suggests that these cells may not be completely or irreversibly quiescent at earlier postnatal ages. Furthermore, regenerative processes can be induced by genetic and pharmacological manipulations, but, more and more reports suggest that regenerative potential declines as the organ of Corti continues to age. In numerous mammalian systems, such effects of aging on regenerative potential are well established. However, in the cochlea, the problem of regeneration has not been traditionally viewed as one of aging. This is an important consideration as current models are unable to elicit widespread regeneration or full recovery of function at adult ages yet regenerative therapies will need to be developed specifically for adult populations. Still, the advent of gene targeting and other genetic manipulations has established mice as critically important models for the study of cochlear development and HC regeneration and suggests that auditory HC regeneration in adult mammals may indeed be possible. Thus, this review will focus on the pursuit of regeneration in the postnatal and adult mouse cochlea and highlight processes that occur during postnatal development, maturation, and aging that could contribute to an age-related decline in regenerative potential. Second, we will draw upon the wealth of knowledge pertaining to age related senescence in tissues outside of the ear to synthesize new insights and potentially guide future research aimed at promoting HC regeneration in the adult cochlea.
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Johnen N, Francart ME, Thelen N, Cloes M, Thiry M. Evidence for a partial epithelial-mesenchymal transition in postnatal stages of rat auditory organ morphogenesis. Histochem Cell Biol 2012; 138:477-88. [PMID: 22610129 DOI: 10.1007/s00418-012-0969-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/07/2012] [Indexed: 12/22/2022]
Abstract
The epithelial-mesenchymal transition (EMT) plays a crucial role in the differentiation of many tissues and organs. So far, an EMT was not detected in the development of the auditory organ. To determine whether an EMT may play a role in the morphogenesis of the auditory organ, we studied the spatial localization of several EMT markers, the cell-cell adhesion molecules and intermediate filament cytoskeletal proteins, in epithelium of the dorsal cochlea during development of the rat Corti organ from E18 (18th embryonic day) until P25 (25th postnatal day). We examined by confocal microscopy immunolabelings on cryosections of whole cochleae with antibodies anti-cytokeratins as well as with antibodies anti-vimentin, anti-E-cadherin and anti-β-catenin. Our results showed a partial loss of E-cadherin and β-catenin and a temporary appearance of vimentin in pillar cells and Deiters between P8 and P10. These observations suggest that a partial EMT might be involved in the remodelling of the Corti organ during the postnatal stages of development in rat.
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Affiliation(s)
- Nicolas Johnen
- Department of Life Sciences, GIGA-Neurosciences, Unit of Cell and Tissue Biology, University of Liege, Avenue de l'hôpital 1, 4000 Liege, Belgium.
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Huh SH, Jones J, Warchol ME, Ornitz DM. Differentiation of the lateral compartment of the cochlea requires a temporally restricted FGF20 signal. PLoS Biol 2012; 10:e1001231. [PMID: 22235191 PMCID: PMC3250500 DOI: 10.1371/journal.pbio.1001231] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2011] [Accepted: 11/18/2011] [Indexed: 12/11/2022] Open
Abstract
A large proportion of age-related hearing loss is caused by loss or damage to outer hair cells in the organ of Corti. The organ of Corti is the mechanosensory transducing apparatus in the inner ear and is composed of inner hair cells, outer hair cells, and highly specialized supporting cells. The mechanisms that regulate differentiation of inner and outer hair cells are not known. Here we report that fibroblast growth factor 20 (FGF20) is required for differentiation of cells in the lateral cochlear compartment (outer hair and supporting cells) within the organ of Corti during a specific developmental time. In the absence of FGF20, mice are deaf and lateral compartment cells remain undifferentiated, postmitotic, and unresponsive to Notch-dependent lateral inhibition. These studies identify developmentally distinct medial (inner hair and supporting cells) and lateral compartments in the developing organ of Corti. The viability and hearing loss in Fgf20 knockout mice suggest that FGF20 may also be a deafness-associated gene in humans.
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MESH Headings
- Animals
- Cell Differentiation/genetics
- Cochlea/cytology
- Cochlea/embryology
- Cochlea/metabolism
- Ear, Inner/cytology
- Ear, Inner/embryology
- Ear, Inner/metabolism
- Female
- Fibroblast Growth Factors/genetics
- Fibroblast Growth Factors/metabolism
- Gene Expression Regulation, Developmental
- Hair Cells, Auditory/cytology
- Hair Cells, Auditory/metabolism
- Hearing Loss/genetics
- Hearing Loss/metabolism
- Humans
- Immunohistochemistry
- Male
- Mice
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Knockout
- Organ Culture Techniques
- Organ of Corti/cytology
- Organ of Corti/embryology
- Organ of Corti/metabolism
- Receptors, Notch/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction/genetics
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Affiliation(s)
- Sung-Ho Huh
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jennifer Jones
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Mark E. Warchol
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - David M. Ornitz
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
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26
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Cai Q, Patel M, Coling D, Hu BH. Transcriptional changes in adhesion-related genes are site-specific during noise-induced cochlear pathogenesis. Neurobiol Dis 2011; 45:723-32. [PMID: 22044737 DOI: 10.1016/j.nbd.2011.10.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 10/06/2011] [Accepted: 10/17/2011] [Indexed: 12/20/2022] Open
Abstract
Cell-cell junctions and junctions between cells and extracellular matrix are essential for maintenance of the structural and functional integrity of the cochlea, and are also a major target of acoustic trauma. While morphological assessments have revealed adhesion dysfunction in noise-traumatized cochleae, the molecular mechanisms responsible for adhesion disruption are not clear. Here, we screened the transcriptional expression of 49 adhesion-related genes in normal rat cochleae and measured the expression changes in the early phases of cochlear pathogenesis after acoustic trauma. We found that genes from four adhesion families, including the immunoglobulin superfamily and the integrin, cadherin, and selectin families, are expressed in the normal cochlea. Exposure to an intense noise at 120dB sound pressure level (SPL) for 2h caused site-specific changes in expression levels in the apical and the basal sections of the sensory epithelium. Expression changes that occurred in the cochlear sensory epithelium were biphasic, with early upregulation at 2h post-noise exposure and subsequent downregulation at 1day post-exposure. Importantly, the altered expression level of seven genes (Sgce, Sell, Itga5, Itgal, Selp, Cntn1 and Col5a1) is related to the level of threshold shift of the auditory brainstem response (ABR), an index reflecting functional change in the cochlea. Notably, the genes showing expression changes exhibited diverse constitutive expression levels and belong to multiple adhesion gene families. The finding of expression changes in multiple families of adhesion genes in a temporal fashion (2h vs. 1day) and a spatial fashion (the apical and the basal sensory epithelia as well as the lateral wall tissue) suggests that acoustic overstimulation provokes a complex response in adhesion genes, which likely involves multiple adhesion-related signaling pathways.
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Affiliation(s)
- Qunfeng Cai
- Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, USA.
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27
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DFNB89, a novel autosomal recessive nonsyndromic hearing impairment locus on chromosome 16q21-q23.2. Hum Genet 2010; 129:379-85. [PMID: 21181198 DOI: 10.1007/s00439-010-0934-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Accepted: 12/12/2010] [Indexed: 10/18/2022]
Abstract
DFNB89 is a novel autosomal recessive nonsyndromic hearing impairment (ARNSHI) locus that was mapped to 16q21-q23.2. Linkage to the region was established by carrying out genome-wide linkage scans in two unrelated, consanguineous Pakistani families segregating ARNSHI. The maximum multipoint LOD score is 9.7 for both families and for each family, a significant maximum LOD score of 6.0 and 3.7 were obtained. The 3-unit support interval and the region of homozygosity for the two families extend from rs717293 (chr16: 62.1 Mb) to rs728929 (chr16: 78.2 Mb) and contain 16.1 Mb of sequence. A total of 146 genes are within the DFNB89 interval. Eight candidate genes, CALB2, CDH1, CDH3, CDH11, HAS3, NOB1, PLEKHG4 and SMPD3, were sequenced, but no potentially causal variants were discovered. DFNB89 is the second ARNSHI locus mapped to chromosome 16.
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28
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Hu BH, Cai Q. Acoustic overstimulation modifies Mcl-1 expression in cochlear sensory epithelial cells. J Neurosci Res 2010; 88:1812-21. [PMID: 20091770 DOI: 10.1002/jnr.22333] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Acoustic overstimulation causes apoptotic cell death in the cochlea. This death process is mediated, in part, by the mitochondrial signaling pathway involving Bcl-2 family proteins. Myeloid cell leukemia sequence 1 (Mcl-l) is an antiapoptotic member of the Bcl-2 family. Its involvement in noise-induced hair cell death has not been characterized. Here we report the endogenous expression and the noise-induced expression of Mcl-1 in Sprague Dawley rat cochleae. In the sensory epithelia of normal cochleae, there is strong constitutive expression of Mcl-1 mRNA, with an expression level higher than that of many other Bcl-2 family genes. The Mcl-1 protein is preferentially expressed in outer hair cells. After exposure to a high level of continuous noise at 115-dB sound pressure level for 1 hr, Mcl-1 expression displays a time-dependent alteration, with up-regulation of Mcl-1 mRNA at 4 hr postexposure and protein up-regulation at 1 day postexposure. Western blot analysis reveals the up-regulated Mcl-1 as the full-length form of Mcl-1. Immunolabeling of the Mcl-1 protein reveals the early increase in Mcl-1 immunoreactivity in the nuclear region of the hair cells displaying apoptotic phenotypes and a subsequent increase in survival hair cells. These results suggest that Mcl-1 is involved in the regulation of hair cell pathogenesis resulting from acoustic stress, possibly by influencing the nuclear events of apoptosis.
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Affiliation(s)
- Bo Hua Hu
- Center for Hearing and Deafness, State University of New York at Buffalo, Buffalo, New York 14214, USA.
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29
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Etournay R, Lepelletier L, Boutet de Monvel J, Michel V, Cayet N, Leibovici M, Weil D, Foucher I, Hardelin JP, Petit C. Cochlear outer hair cells undergo an apical circumference remodeling constrained by the hair bundle shape. Development 2010; 137:1373-83. [PMID: 20332152 DOI: 10.1242/dev.045138] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Epithelial cells acquire diverse shapes relating to their different functions. This is particularly relevant for the cochlear outer hair cells (OHCs), whose apical and basolateral shapes accommodate the functioning of these cells as mechano-electrical and electromechanical transducers, respectively. We uncovered a circumferential shape transition of the apical junctional complex (AJC) of OHCs, which occurs during the early postnatal period in the mouse, prior to hearing onset. Geometric analysis of the OHC apical circumference using immunostaining of the AJC protein ZO1 and Fourier-interpolated contour detection characterizes this transition as a switch from a rounded-hexagon to a non-convex circumference delineating two lateral lobes at the neural side of the cell, with a negative curvature in between. This shape tightly correlates with the 'V'-configuration of the OHC hair bundle, the apical mechanosensitive organelle that converts sound-evoked vibrations into variations in cell membrane potential. The OHC apical circumference remodeling failed or was incomplete in all the mouse mutants affected in hair bundle morphogenesis that we tested. During the normal shape transition, myosin VIIa and myosin II (A and B isoforms) displayed polarized redistributions into and out of the developing lobes, respectively, while Shroom2 and F-actin transiently accumulated in the lobes. Defects in these redistributions were observed in the mutants, paralleling their apical circumference abnormalities. Our results point to a pivotal role for actomyosin cytoskeleton tensions in the reshaping of the OHC apical circumference. We propose that this remodeling contributes to optimize the mechanical coupling between the basal and apical poles of mature OHCs.
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Affiliation(s)
- Raphaël Etournay
- Unité de Génétique et Physiologie de l'Audition, INSERM UMRS587-Université Paris VI, Institut Pasteur, 25 rue du Dr Roux, Paris Cedex 15, France
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30
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Diensthuber M, Oshima K, Heller S. Stem/progenitor cells derived from the cochlear sensory epithelium give rise to spheres with distinct morphologies and features. J Assoc Res Otolaryngol 2009; 10:173-90. [PMID: 19247714 DOI: 10.1007/s10162-009-0161-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Accepted: 02/05/2009] [Indexed: 11/25/2022] Open
Abstract
Nonmammalian vertebrates regenerate lost sensory hair cells by means of asymmetric division of supporting cells. Inner ear or lateral line supporting cells in birds, amphibians, and fish consequently serve as bona fide stem cells resulting in high regenerative capacity of hair cell-bearing organs. Hair cell regeneration does not happen in the mammalian cochlea, but cells with proliferative capacity can be isolated from the neonatal cochlea. These cells have the ability to form clonal floating colonies, so-called spheres, when cultured in nonadherent conditions. We noticed that the sphere population derived from mouse cochlear sensory epithelium cells was heterogeneous, consisting of morphologically distinct sphere types, hereby classified as solid, transitional, and hollow. Cochlear sensory epithelium-derived stem/progenitor cells initially give rise to small solid spheres, which subsequently transition into hollow spheres, a change that is accompanied by epithelial differentiation of the majority of sphere cells. Only solid spheres, and to a lesser extent, transitional spheres, appeared to harbor self-renewing stem cells, whereas hollow spheres could not be consistently propagated. Solid spheres contained significantly more rapidly cycling Pax-2-expressing presumptive otic progenitor cells than hollow spheres. Islet-1, which becomes upregulated in nascent sensory patches, was also more abundant in solid than in hollow spheres. Likewise, hair cell-like cells, characterized by the expression of multiple hair cell markers, differentiated in significantly higher numbers in cell populations derived from solid spheres. We conclude that cochlear sensory epithelium cell populations initially give rise to small solid spheres that have self-renewing capacity before they subsequently convert into hollow spheres, a process that is accompanied by loss of stemness and reduced ability to spontaneously give rise to hair cell-like cells. Solid spheres might, therefore, represent the most suitable sphere type for cell-based assays or animal model transplantation studies aimed at development of cell replacement therapies.
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Affiliation(s)
- Marc Diensthuber
- Departments of Otolaryngology-Head & Neck Surgery and Molecular & Cellular Physiology, School of Medicine, Stanford University, 801 Welch Road, Stanford, CA 94305-5739, USA
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31
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Burns JC, Burns J, Christophel JJ, Collado MS, Magnus C, Carfrae M, Corwin JT. Reinforcement of cell junctions correlates with the absence of hair cell regeneration in mammals and its occurrence in birds. J Comp Neurol 2008; 511:396-414. [PMID: 18803241 DOI: 10.1002/cne.21849] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Debilitating hearing and balance deficits often arise through damage to the inner ear's hair cells. For humans and other mammals, such deficits are permanent, but nonmammalian vertebrates can quickly recover hearing and balance through their innate capacity to regenerate hair cells. The biological basis for this difference has remained unknown, but recent investigations in wounded balance epithelia have shown that proliferation follows cellular spreading at sites of injury. As mammalian ears mature during the first weeks after birth, the capacity for spreading and proliferation declines sharply. In seeking the basis for those declines, we investigated the circumferential bands of F-actin that bracket the apical junctions between supporting cells in the gravity-sensitive utricle. We found that those bands grow much thicker as mice and humans mature postnatally, whereas their counterparts in chickens remain thin from hatching through adulthood. When we cultured utricular epithelia from chickens, we found that cellular spreading and proliferation both continued at high levels, even in the epithelia from adults. In contrast, the substantial reinforcement of the circumferential F-actin bands in mammals coincides with the steep declines in cell spreading and production established in earlier experiments. We propose that the presence of thin F-actin bands at the junctions between avian supporting cells may contribute to the lifelong persistence of their capacity for shape change, cell proliferation, and hair cell replacement and that the postnatal reinforcement of the F-actin bands in maturing humans and other mammals may have an important role in limiting hair cell regeneration.
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Affiliation(s)
- Joseph C Burns
- Department of Biomedical Engineering, University of Virginia School of Engineering and Applied Science, Charlottesville, Virginia 22908, USA.
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32
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Lu Z, Corwin JT. The influence of glycogen synthase kinase 3 in limiting cell addition in the mammalian ear. Dev Neurobiol 2008; 68:1059-75. [DOI: 10.1002/dneu.20635] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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33
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Warchol ME. Characterization of supporting cell phenotype in the avian inner ear: implications for sensory regeneration. Hear Res 2006; 227:11-8. [PMID: 17081713 DOI: 10.1016/j.heares.2006.08.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Revised: 04/26/2006] [Accepted: 08/30/2006] [Indexed: 10/24/2022]
Abstract
The avian inner ear possesses a remarkable capacity for the regeneration of sensory receptors after acoustic trauma or ototoxicity. Most replacement hair cells are created by renewed cell division within the sensory epithelium, although some new hair cells may also arise through nonmitotic mechanisms. Current data indicate that epithelial supporting cells play an essential role in regeneration, by serving as progenitor cells. In order to become progenitors, however, supporting cells may need to undergo partial dedifferentiation. In this review, I describe molecules that are expressed by supporting cells in the avian ear. Although a number of these molecules are likely to be critical to the maintenance of the supporting cell phenotype, we presently know very little about phenotypic changes in supporting cells during the early phase of regeneration.
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Affiliation(s)
- Mark E Warchol
- Department of Otolaryngology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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34
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Kim TS, Nakagawa T, Kitajiri SI, Endo T, Takebayashi S, Iguchi F, Kita T, Tamura T, Ito J. Disruption and restoration of cell-cell junctions in mouse vestibular epithelia following aminoglycoside treatment. Hear Res 2006; 205:201-9. [PMID: 15953529 DOI: 10.1016/j.heares.2005.03.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Accepted: 03/18/2005] [Indexed: 11/16/2022]
Abstract
The intracellular junction complexes, which consist of tight junctions (TJ), adherens junctions (AJ), and desmosomes, mediate cell-cell adhesion in epithelial cells. E-cadherin, which is a major component of AJ, plays a role not only in the maintenance of cell-cell junctions, but also in repressing cell proliferation. In this study, we examined changes of E-cadherin expression in mouse vestibular epithelia following local application of neomycin using immunohistochemistry and western blotting, and morphology of cell-cell junctions by transmission electron microscopy (TEM). Immunohistochemistry and western blotting revealed down-expression of E-cadherin and its consecutive recovery. TEM demonstrated temporal disruption of cell-cell junctions. Morphology of cell-cell junctions was more rapidly restored than recovery of E-cadherin expression. Transient disruption of cell-cell junctions and down-expression of E-cadherin is a rational response for the deletion of dying hair cells, and may be associated with a limited capacity for cell proliferations in mammalian vestibular epithelia following their rapid restoration.
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MESH Headings
- Adherens Junctions/drug effects
- Adherens Junctions/physiology
- Adherens Junctions/ultrastructure
- Analysis of Variance
- Animals
- Anti-Bacterial Agents/toxicity
- Apoptosis/drug effects
- Blotting, Western
- Cadherins/analysis
- Cadherins/biosynthesis
- Cadherins/physiology
- Calbindin 2
- Case-Control Studies
- Cell Adhesion/drug effects
- Cell Adhesion/physiology
- Hair Cells, Auditory/cytology
- Hair Cells, Auditory/drug effects
- Hair Cells, Auditory/metabolism
- Hearing Loss, Sensorineural/chemically induced
- Hearing Loss, Sensorineural/prevention & control
- Immunohistochemistry
- Intercellular Junctions/drug effects
- Intercellular Junctions/pathology
- Intercellular Junctions/physiology
- Mice
- Mice, Inbred C57BL
- Microscopy, Electron, Transmission
- Models, Animal
- Neomycin/toxicity
- S100 Calcium Binding Protein G/analysis
- Saccule and Utricle/drug effects
- Saccule and Utricle/metabolism
- Saccule and Utricle/pathology
- Tight Junctions/drug effects
- Tight Junctions/physiology
- Tight Junctions/ultrastructure
- Vestibule, Labyrinth/cytology
- Vestibule, Labyrinth/drug effects
- Vestibule, Labyrinth/metabolism
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Affiliation(s)
- Tae-Soo Kim
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Sakyo-ku, 606-8507 Kyoto, Japan.
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35
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McKenzie E, Krupin A, Kelley MW. Cellular growth and rearrangement during the development of the mammalian organ of Corti. Dev Dyn 2004; 229:802-12. [PMID: 15042704 DOI: 10.1002/dvdy.10500] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The sensory epithelium of the mammalian cochlea, the organ of Corti, is comprised of ordered rows of cells, including inner and outer hair cells. Recent results suggest that physical changes in the overall size and shape of the cochlear duct, including possible convergence and extension, could play a role in the development of this pattern. To examine this hypothesis, changes in cell size and distribution were determined for different regions of the cochlea duct during embryonic development. In addition, changes in the spatial distribution of sensory precursor cells were determined at different developmental time points based on expression of p27kip1. Unique changes in luminal surface area, cell density, and number of cell contacts were observed for each region of the duct. Moreover, the spatial distribution of p27kip1-positive cells changed from short and broad early in development, to long and narrow. These results are consistent with the hypothesis that convergence and extension plays a role in cellular patterning within the organ of Corti.
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Affiliation(s)
- Erynn McKenzie
- Section on Developmental Neuroscience, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, Maryland, USA
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36
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Abstract
The role of the cochlea is to transduce complex sound waves into electrical neural activity in the auditory nerve. Hair cells of the organ of Corti are the sensory cells of hearing. The inner hair cells perform the transduction and initiate the depolarization of the spiral ganglion neurons. The outer hair cells are accessory sensory cells that enhance the sensitivity and selectivity of the cochlea. Neural feedback loops that bring efferent signals to the outer hair cells assist in sharpening and amplifying the signals. The stria vascularis generates the endocochlear potential and maintains the ionic composition of the endolymph, the fluid in which the apical surface of the hair cells is bathed. The mechanical characteristics of the basilar membrane and its related structures further enhance the frequency selectivity of the auditory transduction mechanism. The tectorial membrane is an extracellular matrix, which provides mass loading on top of the organ of Corti, facilitating deflection of the stereocilia. This review deals with the structure of the normal mature mammalian cochlea and includes recent data on the molecular organization of the main cell types within the cochlea.
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Affiliation(s)
- Yehoash Raphael
- Kresge Hearing Research Institute, The University of Michigan, MSRB 3, Rm 9303, 1150 W. Medical Center Drive, Ann Arbor, MI 48109-0648, USA.
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37
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Simonneau L, Gallego M, Pujol R. Comparative expression patterns of T-, N-, E-cadherins, beta-catenin, and polysialic acid neural cell adhesion molecule in rat cochlea during development: implications for the nature of Kölliker's organ. J Comp Neurol 2003; 459:113-26. [PMID: 12640664 DOI: 10.1002/cne.10604] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We investigated the expression patterns of several cell adhesion molecules (CAMs) during rat cochlea ontogeny, from embryo day 16 to adulthood, with the use of immunohistochemistry: neural cadherin (N-cad) and polysialic acid neural CAM (PSA-NCAM) as two different neural CAM paradigms; epithelial cadherin (E-cad), which was restricted to the epitheloid phenotype; and the cytoplasmic domain-free truncated-cadherin (T-cad). We made the following observations. (1) T-cad was present in all types of fibrocyte and in subdomains within the pillar cells. (2) E- and N-cad were expressed with mutually exclusive patterns and did not overlap with T-cad. All cochlear epithelial cells, including the sensory outer hair cells (OHCs), were E-cad-positive, except for the negative inner hair cells (IHCs) and the nonsensory Kölliker's organ domain close to the IHCs. N-cad expression appeared first in the developing IHCs and then in the neighboring Kölliker's organ in an increasingly mediolateral gradient in opposition to the E-cad gradient. The OHCs, which are never N-cad positive, intensively expressed E-cad, as did the Hensen cells at the beginning of their differentiation. (3) The cadherin-linked molecule beta-catenin, absent in fibrocytes, was detected in all epithelial cell membranes and was prominent in the E-cad-rich modiolar extremity of Kölliker's organ. (4) Gradual PSA-NCAM expression was observed in the lateral portion of Kölliker's organ, and the intense PSA-NCAM expression was seen surrounding the IHCs. As development proceeded, PSA-NCAM immunoreactivity progressively became restricted to the basal poles of the IHCs, where it remained in the adult rat cochlea, suggesting a synaptic plasticity. Synaptic plasticity in rat cochlea and hypotheses about T-cad functions and neosensory features of the Kölliker's organ are discussed.
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Affiliation(s)
- Lionel Simonneau
- Laboratoire de Neurobiologie de l'Audition-Plasticité Synaptique, Institut National de la Santé et de la Recherche Médicale U254, Université Montpellier I, 34090 Montpellier, France.
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38
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Kelley MW. Cell adhesion molecules during inner ear and hair cell development, including notch and its ligands. Curr Top Dev Biol 2003; 57:321-56. [PMID: 14674486 DOI: 10.1016/s0070-2153(03)57011-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Cellular adhesion plays a key role in a number of unique developmental events, including proliferation, cell fate, morphogenesis, neurite outgrowth, fasciculation, and synaptogensis. The number of families of molecules that can mediate cell adhesion and the number of members of each of those families has continued to increase over time. Moreover, the potential for the formation of different pairs of heterodimers with different binding specificities, and for both homo- and hetero-dimeric interactions suggest that a vast number of specific signaling events can be mediated through the expression of different combinations of adhesion factors at different developmental time points. By comparison with the number of known adhesion molecules and their potential effects, our understanding of the role of adhesion in ear development is extremely limited. The patterns of expression for some adhesion molecules have been determined for some aspects of inner ear development. Similarly, with a few exceptions, functional data to indicate the roles of these adhesion molecules are also lacking. However, a consideration of even the limited existing data must lead to the conclusion that adhesion molecules play key roles in all aspects of the development of the auditory system. Unique expression domains for different groups of adhesion molecules within the developing otocyst and ear strongly suggest a role in the determination of different cellular domains. Similarly, the specific expression of adhesion molecules on developing neurites and their target hair cells, suggests a key role for adhesion in the establishment of neuronal connections and possible the development of tonotopy. Finally, the recent demonstration that Cdh23 and Pcdh15 play specific roles in the formation of the hair cell stereociliary bundle provides compelling evidence for the importance of adhesion molecules in the development of stereocilia. With the imminent completion of the mouse genome, it seems likely that the number of adhesion molecules can soon be fixed and that it will then be possible to generate a more comprehensive map of expression of these molecules within the developing inner ear. At the same time, the generation of new transgenic and molecular technologies promises to provide researchers with new tools to examine the specific effects of different adhesion molecules during inner ear development.
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Affiliation(s)
- Matthew W Kelley
- Section on Developmental Neuroscience, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, Maryland 20850, USA
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39
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Abstract
One of the most striking aspects of the cellular pattern within the sensory epithelium of the mammalian cochlea is the presence of two rows of pillar cells in the region between the single row of inner hair cells and the first row of outer hair cells. The factors that regulate pillar cell development have not been determined; however, previous results suggested a key role for fibroblast growth factor receptor 3 (FGFR3). To examine the specific effects of FGFR3 on pillar cell development, we inhibited receptor activation in embryonic cochlear explant cultures. Results indicated that differentiation of pillar cells is dependent on continuous activation of FGFR3. Moreover, transient inhibition of FGFR3 did not inhibit the pillar cell fate permanently, because reactivation of FGFR3 resulted in the resumption of pillar cell differentiation. The effects of increased FGFR3 activation were determined by exposing cochlear explants to FGF2, a strong ligand for several FGF receptors. Treatment with FGF2 led to a significant increase in the number of pillar cells and to a small increase in the number of inner hair cells. These effects were not dependent on cellular proliferation, suggesting that additional pillar cells and inner hair cells were a result of increased recruitment into the prosensory domain. These results indicate that FGF signaling plays a critical role in the commitment and differentiation of pillar cells. Moreover, the position of the pillar cells appears to be determined by the activation of FGFR3 in a subset of the progenitor cells that initially express this receptor.
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40
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Hackett L, Davies D, Helyer R, Kennedy H, Kros C, Lawlor P, Rivolta MN, Holley M. E-cadherin and the differentiation of mammalian vestibular hair cells. Exp Cell Res 2002; 278:19-30. [PMID: 12126954 DOI: 10.1006/excr.2002.5574] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
E-cadherin is expressed in vestibular, mechanosensory epithelia during early embryonic development. During late embryonic and neonatal stages it is expressed in supporting cells but down-regulated in differentiating sensory hair cells. We used a conditionally immortal cell line (UB/UE-1) from the neonatal mouse utricle to test the hypothesis that constitutive expression of E-cadherin inhibits the progression of hair cell differentiation. Under differentiating culture conditions, transfected E-cadherin inhibited expression of the cytoskeletal protein myosin VIIa and functional expression of both acetylcholine receptors and potassium channels, which are normally expressed by neonatal hair cells. However, it had no effect on the expression of the transcription factor Brn3c or the cytoskeletal protein fimbrin, which are also expressed by neonatal hair cells. The number of adherens junctions increased significantly under differentiating conditions but there was no detectable change in formation of tight junctions or gap junctions. However, E-cadherin expression led to density-dependent cell death under differentiating conditions. We have shown that E-cadherin is expressed in vestibular supporting cells, which form the basis of the sensory epithelium, but that constitutive expression inhibits the full differentiation of hair cells. Down-regulation of E-cadherin is thus likely to be a key element in the regeneration of hair cells.
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Affiliation(s)
- Lucy Hackett
- Department of Physiology, School of Medical Sciences, University of Bristol, University Walk, Bristol, BS8 1TD, United Kingdom
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41
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Lawoko-Kerali G, Rivolta MN, Holley M. Expression of the transcription factors GATA3 and Pax2 during development of the mammalian inner ear. J Comp Neurol 2002; 442:378-91. [PMID: 11793341 DOI: 10.1002/cne.10088] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The transcription factors GATA3 and Pax2 are expressed throughout development of the mouse inner ear. We have used antibodies to study their temporal and spatial expression patterns from embryonic days E8-E16.5. The two factors show reciprocal relationships in the regional patterning of the early otocyst and cellular patterning within the sensory epithelia. GATA3 is expressed in the whole otic placode at E8. In the otocyst at E9.5-10.5, the distribution is lateral and complementary to the medial expression pattern of Pax2. Only Pax2 is expressed in the endolymphatic duct, but both factors are expressed in the cochlea. At E11.5-13.5, GATA3 is expressed strongly in the cochlea, but in the dorsal, vestibular region it is downregulated. In all sensory epithelia, downregulation coincides with sensory innervation. Pax2 is expressed in all sensory and some nonsensory epithelia, but within sensory epithelia at E16.5 it is restricted to hair cells. GATA3 is expressed throughout key periods of cell proliferation, fate determination, and differentiation and is not specifically associated with any of these processes. Expression persists most strongly in the main components of the developing auditory system. These include the auditory sensory epithelium, the afferent and efferent nerves, and the mesenchymal and ectodermal cells in regions that form key parts of the middle and outer ear. GATA3 is thus expressed in functionally distinct groups of cells that integrate to form a complete sensory system. The results suggest that both factors may be involved in tissue compartmentalisation, morphogenesis, and cell signalling.
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42
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Wilson SM, Householder DB, Coppola V, Tessarollo L, Fritzsch B, Lee EC, Goss D, Carlson GA, Copeland NG, Jenkins NA. Mutations in Cdh23 cause nonsyndromic hearing loss in waltzer mice. Genomics 2001; 74:228-33. [PMID: 11386759 DOI: 10.1006/geno.2001.6554] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mutations at the waltzer (v) locus result in deafness and vestibular dysfunction due to degeneration of the neuroepithelium within the inner ear. Here, we use a positional cloning approach to show that waltzer encodes a novel cadherin (Cdh23), which is most closely related to the Drosophila Fat protein. A single nucleotide deletion in the v(J) allele and a single nucleotide insertion in the v allele are predicted to truncate each protein near the N-terminus and produce a functional null allele. In situ hybridization analysis showed that Cdh23 is expressed in the sensory hair cells of the inner ear, where it has been suggested to be a molecule critical for crosslinking of the stereocilia. In addition, Cdh23 is expressed in the urticulo-saccular foramen,the ductus reuniens, and Reissner's membrane, suggesting that Cdh23 may also be involved in maintaining the ionic composition of the endolymph. Finally, mutations in human CDH23 have recently been described for two loci, DFNB12 and USH1D, which cause nonsyndromic deafness, identifying waltzer as a mouse model for human hearing loss.
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MESH Headings
- Alleles
- Amino Acid Sequence
- Animals
- Cadherin Related Proteins
- Cadherins/biosynthesis
- Cadherins/genetics
- Chromosome Mapping
- Chromosomes, Artificial, Bacterial
- Chromosomes, Artificial, Yeast
- Cloning, Molecular
- Crosses, Genetic
- DNA, Complementary/metabolism
- Deafness/genetics
- Deafness/metabolism
- Drosophila
- Gene Library
- Humans
- In Situ Hybridization
- Membrane Proteins/genetics
- Mice
- Mice, Mutant Strains
- Models, Genetic
- Molecular Sequence Data
- Mutation
- Physical Chromosome Mapping
- Point Mutation
- Polymorphism, Genetic
- Polymorphism, Restriction Fragment Length
- Protein Structure, Tertiary
- Reverse Transcriptase Polymerase Chain Reaction
- Tissue Distribution
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Affiliation(s)
- S M Wilson
- Mouse Cancer Genetics Program, National Cancer Institute-Frederick, Frederick, Maryland 21702, USA
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43
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Abstract
E-cadherin and the associated catenin complex have been recognised as performing a key role in cell adhesion. Loss of cell adhesion is seen as a key step in the cascade leading to tumour metastasis. The ability of both extra- and intracellular factors to regulate E-cadherin-mediated cell adhesion in physiological processes has provided insight into both the interactions of the E-cadherin-catenin complex, and possible mechanisms utilised by tumours in the process of metastasis. The interaction of the E-cadherin-catenin complex with various regulating factors, their effect on cell signalling pathways, and the relationship with the metastatic potential of tumours are reviewed.
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Affiliation(s)
- I R Beavon
- Department of Anatomical Pathology, School of Pathology, South African Institute for Medical Research and University of the Witwatersrand, Johannesburg, South Africa.
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44
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Abstract
The ability of tumours to metastasis is regarded as one of the hallmarks of malignancy. The process through which tumours evolve to achieve this has been termed the metastatic cascade. This cascade has been the subject of much investigation over many years. One of the vital events identified by these investigations is the reduction of adhesion between tumour cells facilitating invasion of the surrounding tissues and vascular channels, ultimately leading to the development of a distant metastasis. E-cadherin and its associated catenin complex have been identified as key molecules in cell adhesion. This review looks at the structure and interaction of the E-cadherin-catenin complex and the factors that appear to regulate E-cadherin expression and thus cell adhesion. From the data gathered, it has become possible to propose the hypothesis that the development of tumour hypoxia is the initiating factor that sets the tumour on the road to metastasis.
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Affiliation(s)
- I R Beavon
- Department of Anatomical Pathology, School of Pathology, South African Institute for Medical Research, Johannesburg, South Africa.
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Abstract
Tenascin-C is a glycoprotein of the extracellular matrix that acts in vitro as both a permissive and a nonpermissive substrate for neurite growth. We analyzed, by immunocytochemistry, the distribution of tenascin-C along neural growth pathways in the developing mouse cochlea. In the spiral lamina, tenascin-C coexists in a region where nerve bundles arborize. In the organ of Corti, tenascin-C lines the neural pathways along pillar and Deiters' cells before and during the time of nerve fiber ingrowth. By embryonic day 16, tenascin-C is abundant on the pillar side of the inner hair cell but does not accumulate on the modiolar side until about birth, a time after the arrival of afferent fibers. The synaptic zones beneath outer hair cells are strongly labeled during the time when early events in afferent synaptogenesis are progressing but not during the time of efferent synaptogenesis. At the age when most neural growth ceases, tenascin-C immunoreactivity disappears. Faint tenascin-C immunolabeling of normal hair cells, strong tenascin immunolabeling in pathological hair cells of Bronx waltzer (bv/bv) mice, and staining for beta-galactosidase, whose gene replaces tenascin in a "knockout" mouse, indicate that hair cells supply at least part of the tenascin-C. The changing composition of the extracellular matrix in the synaptic region during afferent and efferent synaptogenesis is consistent with a role for tenascin in synaptogenesis. The presence of tenascin-C along the growth routes of nerve fibers, particularly toward the outer hair cells, raises the possibility that growth cone interactions with tenascin-C helps to guide nerve fibers in the cochlea.
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Affiliation(s)
- D S Whitlon
- Audiology and Hearing Sciences Program and Institute for Neuroscience, Northwestern University, Evanston, Illinois 60208, USA.
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46
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Leonova EV, Raphael Y. Organization of cell junctions and cytoskeleton in the reticular lamina in normal and ototoxically damaged organ of Corti. Hear Res 1997; 113:14-28. [PMID: 9387983 DOI: 10.1016/s0378-5955(97)00130-5] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The reticular lamina creates an ion barrier, withstands mechanical stress in the organ of Corti and is able to maintain its integrity during and after severe hair cell loss. Tight junctions maintain the ionic gradient whereas adherens junctions and the cytoskeleton are responsible for the integrity and mechanical resistance of tissues. In this study we used immunofluorescence and electron microscopy to examine the distribution of proteins of tight junctions (cingulin), adherens junctions (E-cadherin, alpha- and beta-catenin) and the cytoskeleton (actin, cytokeratin and tubulin) in whole-mounts of the normal and ototoxically damaged organ of Corti. In normal ears the proteins of adherens junctions were found in all cell types of the reticular lamina. We now demonstrate that all cells forming the reticular lamina partially overlap each other organizing extensive cell contacts with a complex three-dimensional shape. During scar formation, the tight junctions as well as adherens junctions between hair and supporting cells appeared in two distinct focal planes, which could help to preserve the ionic barrier and tissue integrity during hair cell degeneration. During scar formation all cytoskeletal structures in the reticular lamina were reorganized in a specific spatio-temporal pattern. We present a three-dimensional model of cell contact organization in the reticular lamina of normal ears and during scar formation.
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Affiliation(s)
- E V Leonova
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor 48109-0648, USA.
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47
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Mahendrasingam S, Katori Y, Furness DN, Hackney CM. Ultrastructural localization of cadherin in the adult guinea-pig organ of Corti. Hear Res 1997; 111:85-92. [PMID: 9307314 DOI: 10.1016/s0378-5955(97)00091-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The apices of the majority of cells of the organ of Corti are connected together by junctional complexes to form the reticular lamina, a barrier that prevents the mixing of endolymph and perilymph. These complexes include tight junctions, adherens junctions and desmosomes. Further information is required about the identity and distribution of the molecules involved in these connections if the function and organization of the reticular lamina are to be well understood. One major category of molecules occurring in adherens junctions and desmosomes, and involved in the maintenance of tissue integrity, is the cadherins. However, although cadherin has been identified in junctions between supporting cells in the adult mammalian organ of Corti at the light microscopic level, its ultrastructural distribution has not so far been described. A post-embedding immunogold labelling technique has therefore been used in conjunction with a monoclonal antibody to cadherin to investigate its ultrastructural distribution in the adult guinea-pig reticular lamina. Immunolabelling is observed in hair cell-supporting cell junctions and in supporting cell-supporting cell junctions. In addition, there is more labelling associated with inner hair cell-supporting cell junctions than with outer hair cell-supporting cell junctions. This may indicate that the junctions associated with the two types of hair cell have different functional properties.
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MESH Headings
- Animals
- Cadherins/analysis
- Cadherins/ultrastructure
- Guinea Pigs
- Hair Cells, Auditory, Inner/metabolism
- Hair Cells, Auditory, Inner/ultrastructure
- Hair Cells, Auditory, Outer/metabolism
- Hair Cells, Auditory, Outer/ultrastructure
- Immunohistochemistry
- Intercellular Junctions/metabolism
- Intercellular Junctions/ultrastructure
- Microscopy, Electron
- Organ of Corti/metabolism
- Organ of Corti/ultrastructure
- Tissue Embedding
- Vestibular Nucleus, Lateral/metabolism
- Vestibular Nucleus, Lateral/ultrastructure
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Affiliation(s)
- S Mahendrasingam
- Department of Communication and Neuroscience, Keele University, Staffs, UK
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48
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Abstract
Polysialic acid (PSA), an unusual molecule covalently attached to the neural cell adhesion molecule, NCAM, has been shown to regulate cell-to-cell and cell-to-matrix interactions by interfering with the binding of cell-surface adhesion molecules. We used immunocytochemistry to map the temporospatial distribution of PSA in the mouse cochlea between embryonic day 16 and postnatal day 32 and compared it to the known timetable of neural growth and development. Polysialic acid immunoreactivity develops along a temporospatial gradient beginning in the basal turn and progressing to the apical turn. The expression is transitory on spiral ganglion neurons, intraganglionic bundles, radial bundles, and outer hair cells. Immunoreactivity diminishes progressively from the basal turn to the apical turn. Immunolabeling is maintained to adulthood on fibers in the inner spiral and inner pillar bundles, bundles which have been suggested to sprout continually and grow even in older animals. Inner hair cells are never immunolabeled. The temporo-spatial expression of PSA suggests its involvement in neural growth, whereas its extinction correlates with the time of onset of nerve-receptor interactions.
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Affiliation(s)
- D S Whitlon
- Waisman Center, University of Wisconsin-Madison 53705, USA
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49
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Chardin S, Romand R. Factors modulating supernumerary hair cell production in the postnatal rat cochlea in vitro. Int J Dev Neurosci 1997; 15:497-507. [PMID: 9263028 DOI: 10.1016/s0736-5748(96)00106-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
It has been shown in the past that extra hair cells or supernumerary cells can be produced when neonatal cochleae are maintained in vitro. In this report, we investigated the effects of the culture methods, molecules and growth factors that are thought to be involved in cell proliferation. Quantitative studies of supernumerary hair cells were made by measuring the cell density over the entire spiral lamina at two postnatal stages: birth and 3 days after birth. With a standard feeding solution without serum, a difference in cell density was observed between the two methods of culture. Cochlear explants in a standard feeding solution supplemented with serum showed an increase of cell density only when the explantation is made at birth. Retinoic acid added to the standard feeding solution did not increase the hair cell density, while insulin induced an increase, especially at 5 micrograms/ml. Several growth factors were tested. Epidermal growth factor (EGF) presented a dose dependent effect with an increase of up to 30% of hair cell density that was observed in the basal region when the explantation was made at birth. Transforming growth factor-alpha did not induce an increase of cell density, whereas transforming growth factor-beta presented an effect on hair cell density, with a dose dependent effect reaching 37.4% for the basal inner hair cells. Interpretation of these results is limited because of the lack of data concerning the presence of specific membrane receptors. One possibility is that insulin stimulates hair cell differentiation from existing undifferentiated cells. Another hypothesis may be related to the EGF and transforming growth factor-beta, where these molecules might induce transdifferentiation of cells by acting on the transmembrane molecules and the extracellular matrix.
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Affiliation(s)
- S Chardin
- Laboratoire de Neurobiologie, Université Blaise Pascal-Clermont II, 63177 Aubicre, France
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50
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Abstract
The dimensions of the apical surfaces of hair cells were measured in guinea pigs, aged from 3 weeks before term to 25 weeks after birth. In the basal two-thirds of the cochlea, the apical surfaces of the outer hair cells and their supporting cells changed with age, shrinking in a direction radial across the cochlear duct. There was an associated widening of the angle of the 'V' of the rows of stereocilia. Further apically, between 12 and 16 mm from the base of the cochlea, the outer hair cells and their supporting cells underwent the opposite change, becoming wider in a radial direction with age. The changes were seen before birth and continued for more than 3 weeks after birth. The results suggest that the guinea pig cochlea continues certain developmental processes for a considerable time after birth.
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Affiliation(s)
- S Zhou
- Department of Physiology and Pharmacology, University of Queensland, Australia.
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