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Zhang X, Liu Y, Zhang L, Yang Z, Shao Y, Jiang C, Wang Q, Fang X, Xu Y, Wang H, Zhang S, Zhu Y. Genetic variations in protocadherin 15 and their interactions with noise exposure associated with noise-induced hearing loss in Chinese population. ENVIRONMENTAL RESEARCH 2014; 135:247-252. [PMID: 25462672 DOI: 10.1016/j.envres.2014.09.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Revised: 09/23/2014] [Accepted: 09/25/2014] [Indexed: 06/04/2023]
Abstract
OBJECTIVES The purpose of this study was to examine the associations between genetic variations in the Protocadherin 15 gene (PCDH15) and the risk to noise induced hearing loss (NIHL) in a Chinese population. METHODS A case-control study was conducted with 476 noise-sensitive workers (NIHL) and 475 noise-resistant workers (normal) matched for gender, years of noise exposure, and intensity of noise exposure. 13 tag single-nucleotide polymorphisms in PCDH15 were genotyped using nanofluidic dynamic arrays on the Fluidigm platform. Multiple logistic regression was used to analyze the associations of genetic variations of PCDH15 with NIHL adjusted by age, smoking/drinking status, and cumulative noise exposure and their interactions with noise exposure. RESULTS The allele frequency and genotypes of rs1104085 were significantly associated with the risk of NIHL(P=0.009 and 0.005 respectively ). The subjects carrying variant alleles (CT or CC) of rs11004085 had a decreased the risk for NIHL (adjusted odds ratio=0.587, 95% confidence interval 0.409-0.842) compared with subjects who had the wild-type (TT) homozygotes. The interactions were found between the SNPs of rs1100085, rs10825122, rs1930146, rs2384437, rs4540756, and rs2384375 and noise exposure. CONCLUSIONS Genetic variations of PCDH15 and their interactions with occupational noise exposure are associated with genetic susceptibility to NIHL and modify the risk of noise induced hearing loss.
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Affiliation(s)
- Xuhui Zhang
- Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, PR China
| | - Yi Liu
- Department of Epidemiology and Biostatistics, Zhejiang University School of Public Health, Hangzhou 310058, Zhejiang, PR China
| | - Lei Zhang
- Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, PR China
| | - Zhangping Yang
- Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, PR China
| | - Yuxian Shao
- Hangzhou Prevention and Treatment for Occupational Diseases, Hangzhou 310014, Zhejiang, PR China
| | - Caixia Jiang
- Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, PR China
| | - Qiang Wang
- Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, PR China
| | - Xinyan Fang
- Yongkang Center for Disease Control and Prevention, Yongkang 321304, PR China
| | - Yuyang Xu
- Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, PR China
| | - Hao Wang
- Yongkang Center for Disease Control and Prevention, Yongkang 321304, PR China
| | - Shuai Zhang
- Department of Pathology, Zhejiang University School of Medicine, Hangzhou 310058, PR China
| | - Yimin Zhu
- Department of Epidemiology and Biostatistics, Zhejiang University School of Public Health, Hangzhou 310058, Zhejiang, PR China.
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Abstract
PURPOSE OF THE REVIEW This article presents research findings from two invertebrate model systems with potential to advance both the understanding of noise-induced hearing loss mechanisms and the development of putative therapies to reduce human noise damage. RECENT FINDINGS Work on sea anemone hair bundles, which resemble auditory hair cells, has revealed secretions that exhibit astonishing healing properties not only for damaged hair bundles, but also for vertebrate lateral line neuromasts. We present progress on identifying functional components of the secretions, and their mechanisms of repair. The second model, the Johnston's organ in Drosophila, is also genetically homologous to hair cells and shows noise-induced hearing loss similar to vertebrates. Drosophila offers genetic and molecular insight into noise sensitivity and pathways that can be manipulated to reduce stress and damage from noise. SUMMARY Using the comparative approach is a productive avenue to understanding basic mechanisms, in this case cellular responses to noise trauma. Expanding study of these systems may accelerate identification of strategies to reduce or prevent noise damage in the human ear.
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Affiliation(s)
- Kevin W Christie
- Department of Biology, The University of Iowa, Iowa City, Iowa 52246
| | - Daniel F. Eberl
- Department of Biology, The University of Iowa, Iowa City, Iowa 52246
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Lu Y, Zhou X, Jin Z, Cheng J, Shen W, Ji F, Liu L, Zhang X, Zhang M, Cao Y, Han D, Choy K, Yuan H. Resolving the genetic heterogeneity of prelingual hearing loss within one family: Performance comparison and application of two targeted next generation sequencing approaches. J Hum Genet 2014; 59:599-607. [PMID: 25231367 PMCID: PMC4521291 DOI: 10.1038/jhg.2014.78] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 08/11/2014] [Accepted: 08/12/2014] [Indexed: 12/30/2022]
Abstract
Here, we report an unconventional Chinese pedigree consisting of three branches all segregating prelingual hearing loss (HL) with unclear inheritance pattern. After identifying the cause of one branch as maternally inherited aminoglycoside-induced HL, targeted next generation sequencing (NGS) was applied to identify the genetic causes for the other two branches. One affected subject from each branch was subject to targeted NGS whose genomic DNA was enriched either by whole-exome capture (Agilent SureSelect All Exon 50 Mb) or by candidate genes capture (Agilent SureSelect custom kit). By NGS analysis, we identified that patients from Branch A were compound heterozygous for p.E1006K and p.D1663V in the CDH23 (DFNB12) gene; and patients from Branch B were homozygous for IVS7-2A>G in the SLC26A4 (DFNB4) gene. Both CDH23 mutations altered conserved calcium binding sites of the extracellular cadherin domains. The co-occurrence of three different genetic causes in this family was exceedingly rare but fully compatible with the mutation spectrum of HL. Our study has also raised several technical and analytical issues when applying the NGS technique to genetic testing.
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Affiliation(s)
- Yu Lu
- Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, China
| | - Xueya Zhou
- 1] MOE Key Laboratory of Bioinformatics, Bioinformatics Division and Center for Synthetic and Systems Biology, TNLIST/Department of Automation, Tsinghua University, Beijing, China [2] Department of Psychiatry, The University of Hong Kong, Hong Kong, SAR, China
| | - Zhanguo Jin
- Department of Otolaryngology, Chinese PLA Air Force General Hospital, Beijing, China
| | - Jing Cheng
- Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, China
| | - Weidong Shen
- Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, China
| | - Fei Ji
- Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, China
| | - Liyang Liu
- MOE Key Laboratory of Bioinformatics, Bioinformatics Division and Center for Synthetic and Systems Biology, TNLIST/Department of Automation, Tsinghua University, Beijing, China
| | - Xuegong Zhang
- MOE Key Laboratory of Bioinformatics, Bioinformatics Division and Center for Synthetic and Systems Biology, TNLIST/Department of Automation, Tsinghua University, Beijing, China
| | - Michael Zhang
- 1] MOE Key Laboratory of Bioinformatics, Bioinformatics Division and Center for Synthetic and Systems Biology, TNLIST/Department of Automation, Tsinghua University, Beijing, China [2] MCB, Center for Systems Biology, The University of Texas at Dallas, Richardson, TX, USA
| | - Ye Cao
- 1] Department of Obstetrics and Gynaecology, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR, China [2] CUHK-University of Utrecht Joint Centre for Language, Mind and Brain, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR, China
| | - Dongyi Han
- Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, China
| | - KwongWai Choy
- 1] Department of Obstetrics and Gynaecology, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR, China [2] CUHK-University of Utrecht Joint Centre for Language, Mind and Brain, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR, China
| | - Huijun Yuan
- Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, China
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54
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Abstract
Uniquely among human senses, hearing is not simply a passive response to stimulation. Our auditory system is instead enhanced by an active process in cochlear hair cells that amplifies acoustic signals several hundred-fold, sharpens frequency selectivity and broadens the ear's dynamic range. Active motility of the mechanoreceptive hair bundles underlies the active process in amphibians and some reptiles; in mammals, this mechanism operates in conjunction with prestin-based somatic motility. Both individual hair bundles and the cochlea as a whole operate near a dynamical instability, the Hopf bifurcation, which accounts for the cardinal features of the active process.
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55
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Pirolli D, Sciandra F, Bozzi M, Giardina B, Brancaccio A, De Rosa MC. Insights from molecular dynamics simulations: structural basis for the V567D mutation-induced instability of zebrafish alpha-dystroglycan and comparison with the murine model. PLoS One 2014; 9:e103866. [PMID: 25078606 PMCID: PMC4117597 DOI: 10.1371/journal.pone.0103866] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 07/03/2014] [Indexed: 11/19/2022] Open
Abstract
A missense amino acid mutation of valine to aspartic acid in 567 position of alpha-dystroglycan (DG), identified in dag1-mutated zebrafish, results in a reduced transcription and a complete absence of the protein. Lacking experimental structural data for zebrafish DG domains, the detailed mechanism for the observed mutation-induced destabilization of the DG complex and membrane damage, remained unclear. With the aim to contribute to a better clarification of the structure-function relationships featuring the DG complex, three-dimensional structural models of wild-type and mutant (V567D) C-terminal domain of alpha-DG from zebrafish were constructed by a template-based modelling approach. We then ran extensive molecular dynamics (MD) simulations to reveal the structural and dynamic properties of the C-terminal domain and to evaluate the effect of the single mutation on alpha-DG stability. A comparative study has been also carried out on our previously generated model of murine alpha-DG C-terminal domain including the I591D mutation, which is topologically equivalent to the V567D mutation found in zebrafish. Trajectories from MD simulations were analyzed in detail, revealing extensive structural disorder involving multiple beta-strands in the mutated variant of the zebrafish protein whereas local effects have been detected in the murine protein. A biochemical analysis of the murine alpha-DG mutant I591D confirmed a pronounced instability of the protein. Taken together, the computational and biochemical analysis suggest that the V567D/I591D mutation, belonging to the G beta-strand, plays a key role in inducing a destabilization of the alpha-DG C-terminal Ig-like domain that could possibly affect and propagate to the entire DG complex. The structural features herein identified may be of crucial help to understand the molecular basis of primary dystroglycanopathies.
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Affiliation(s)
- Davide Pirolli
- Istituto di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Francesca Sciandra
- Istituto di Chimica del Riconoscimento Molecolare (ICRM) - CNR c/o Università Cattolica del Sacro Cuore, Rome, Italy
| | - Manuela Bozzi
- Istituto di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Bruno Giardina
- Istituto di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore, Rome, Italy
- Istituto di Chimica del Riconoscimento Molecolare (ICRM) - CNR c/o Università Cattolica del Sacro Cuore, Rome, Italy
| | - Andrea Brancaccio
- Istituto di Chimica del Riconoscimento Molecolare (ICRM) - CNR c/o Università Cattolica del Sacro Cuore, Rome, Italy
| | - Maria Cristina De Rosa
- Istituto di Chimica del Riconoscimento Molecolare (ICRM) - CNR c/o Università Cattolica del Sacro Cuore, Rome, Italy
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56
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Crawley SW, Shifrin DA, Grega-Larson NE, McConnell RE, Benesh AE, Mao S, Zheng Y, Zheng QY, Nam KT, Millis BA, Kachar B, Tyska MJ. Intestinal brush border assembly driven by protocadherin-based intermicrovillar adhesion. Cell 2014; 157:433-446. [PMID: 24725409 DOI: 10.1016/j.cell.2014.01.067] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Revised: 12/19/2013] [Accepted: 01/28/2014] [Indexed: 12/17/2022]
Abstract
Transporting epithelial cells build apical microvilli to increase membrane surface area and enhance absorptive capacity. The intestinal brush border provides an elaborate example with tightly packed microvilli that function in nutrient absorption and host defense. Although the brush border is essential for physiological homeostasis, its assembly is poorly understood. We found that brush border assembly is driven by the formation of Ca(2+)-dependent adhesion links between adjacent microvilli. Intermicrovillar links are composed of protocadherin-24 and mucin-like protocadherin, which target to microvillar tips and interact to form a trans-heterophilic complex. The cytoplasmic domains of microvillar protocadherins interact with the scaffolding protein, harmonin, and myosin-7b, which promote localization to microvillar tips. Finally, a mouse model of Usher syndrome lacking harmonin exhibits microvillar protocadherin mislocalization and severe defects in brush border morphology. These data reveal an adhesion-based mechanism for brush border assembly and illuminate the basis of intestinal pathology in patients with Usher syndrome. PAPERFLICK:
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Affiliation(s)
- Scott W Crawley
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - David A Shifrin
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Nathan E Grega-Larson
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Russell E McConnell
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Andrew E Benesh
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Suli Mao
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Yuxi Zheng
- Department of Otolaryngology-HNS, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Qing Yin Zheng
- Department of Otolaryngology-HNS, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ki Taek Nam
- Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Bryan A Millis
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Bechara Kachar
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Matthew J Tyska
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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57
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Resolving the molecular mechanism of cadherin catch bond formation. Nat Commun 2014; 5:3941. [PMID: 24887573 DOI: 10.1038/ncomms4941] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 04/23/2014] [Indexed: 11/09/2022] Open
Abstract
Classical cadherin Ca(2+)-dependent cell-cell adhesion proteins play key roles in embryogenesis and in maintaining tissue integrity. Cadherins mediate robust adhesion by binding in multiple conformations. One of these adhesive states, called an X-dimer, forms catch bonds that strengthen and become longer lived in the presence of mechanical force. Here we use single-molecule force-clamp spectroscopy with an atomic force microscope along with molecular dynamics and steered molecular dynamics simulations to resolve the molecular mechanisms underlying catch bond formation and the role of Ca(2+) ions in this process. Our data suggest that tensile force bends the cadherin extracellular region such that they form long-lived, force-induced hydrogen bonds that lock X-dimers into tighter contact. When Ca(2+) concentration is decreased, fewer de novo hydrogen bonds are formed and catch bond formation is eliminated.
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58
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Sotomayor M, Gaudet R, Corey DP. Sorting out a promiscuous superfamily: towards cadherin connectomics. Trends Cell Biol 2014; 24:524-36. [PMID: 24794279 DOI: 10.1016/j.tcb.2014.03.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 03/23/2014] [Accepted: 03/25/2014] [Indexed: 12/21/2022]
Abstract
Members of the cadherin superfamily of proteins are involved in diverse biological processes such as morphogenesis, sound transduction, and neuronal connectivity. Key to cadherin function is their extracellular domain containing cadherin repeats, which can mediate interactions involved in adhesion and cell signaling. Recent cellular, biochemical, and structural studies have revealed that physical interaction among cadherins is more complex than originally thought. Here we review work on new cadherin complexes and discuss how the classification of the mammalian family can be used to search for additional cadherin-interacting partners. We also highlight some of the challenges in cadherin research; namely, the characterization of a cadherin connectome in biochemical and structural terms, as well as the elucidation of molecular mechanisms underlying the functional diversity of nonclassical cadherins in vivo.
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Affiliation(s)
- Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus OH 43210, USA.
| | - Rachelle Gaudet
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
| | - David P Corey
- Howard Hughes Medical Institute, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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59
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Koussa MA, Sotomayor M, Wong WP. Protocol for sortase-mediated construction of DNA-protein hybrids and functional nanostructures. Methods 2014; 67:134-41. [PMID: 24568941 DOI: 10.1016/j.ymeth.2014.02.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 02/07/2014] [Accepted: 02/11/2014] [Indexed: 11/18/2022] Open
Abstract
Recent methods in DNA nanotechnology are enabling the creation of intricate nanostructures through the use of programmable, bottom-up self-assembly. However, structures consisting only of DNA are limited in their ability to act on other biomolecules. Proteins, on the other hand, perform a variety of functions on biological materials, but directed control of the self-assembly process remains a challenge. While DNA-protein hybrids have the potential to provide the best-of-both-worlds, they can be difficult to create as many of the conventional techniques for linking proteins to DNA render proteins dysfunctional. We present here a sortase-based protocol for covalently coupling proteins to DNA with minimal disturbance to protein function. To accomplish this we have developed a two-step process. First, a small synthetic peptide is bioorthogonally and covalently coupled to a DNA oligo using click chemistry. Next, the DNA-peptide chimera is covalently linked to a protein of interest under protein-compatible conditions using the enzyme sortase. Our protocol allows for the simple coupling and purification of a functional DNA-protein hybrid. We use this technique to form oligos bearing cadherin-23 and protocadherin-15 protein fragments. Upon incorporation into a linear M13 scaffold, these protein-DNA hybrids serve as the gate to a binary nanoswitch. The outlined protocol is reliable and modular, facilitating the construction of libraries of oligos and proteins that can be combined to form functional DNA-protein nanostructures. These structures will enable a new class of functional nanostructures, which could be used for therapeutic and industrial processes.
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Affiliation(s)
- Mounir A Koussa
- Program in Neuroscience, Department of Neurobiology, Harvard Medical School, Boston, MA, United States
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, United States
| | - Wesley P Wong
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, United States; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, United States.
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60
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Abstract
The 10 different genes associated with the deaf/blind disorder, Usher syndrome, encode a number of structurally and functionally distinct proteins, most expressed as multiple isoforms/protein variants. Functional characterization of these proteins suggests a role in stereocilia development in cochlear hair cells, likely owing to adhesive interactions in hair bundles. In mature hair cells, homodimers of the Usher cadherins, cadherin 23 and protocadherin 15, interact to form a structural fiber, the tip link, and the linkages that anchor the taller stereocilia's actin cytoskeleton core to the shorter adjacent stereocilia and the elusive mechanotransduction channels, explaining the deafness phenotype when these molecular interactions are perturbed. The conundrum is that photoreceptors lack a synonymous mechanotransduction apparatus, and so a common theory for Usher protein function in the two neurosensory cell types affected in Usher syndrome is lacking. Recent evidence linking photoreceptor cell dysfunction in the shaker 1 mouse model for Usher syndrome to light-induced protein translocation defects, combined with localization of an Usher protein interactome at the periciliary region of the photoreceptors suggests Usher proteins might regulate protein trafficking between the inner and outer segments of photoreceptors. A distinct Usher protein complex is trafficked to the ribbon synapses of hair cells, and synaptic defects have been reported in Usher mutants in both hair cells and photoreceptors. This review aims to clarify what is known about Usher protein function at the synaptic and apical poles of hair cells and photoreceptors and the prospects for identifying a unifying pathobiological mechanism to explain deaf/blindness in Usher syndrome.
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61
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Indzhykulian AA, Stepanyan R, Nelina A, Spinelli KJ, Ahmed ZM, Belyantseva IA, Friedman TB, Barr-Gillespie PG, Frolenkov GI. Molecular remodeling of tip links underlies mechanosensory regeneration in auditory hair cells. PLoS Biol 2013; 11:e1001583. [PMID: 23776407 PMCID: PMC3679001 DOI: 10.1371/journal.pbio.1001583] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 05/02/2013] [Indexed: 11/18/2022] Open
Abstract
Sound detection by inner ear hair cells requires tip links that interconnect mechanosensory stereocilia and convey force to yet unidentified transduction channels. Current models postulate a static composition of the tip link, with protocadherin 15 (PCDH15) at the lower and cadherin 23 (CDH23) at the upper end of the link. In terminally differentiated mammalian auditory hair cells, tip links are subjected to sound-induced forces throughout an organism's life. Although hair cells can regenerate disrupted tip links and restore hearing, the molecular details of this process are unknown. We developed a novel implementation of backscatter electron scanning microscopy to visualize simultaneously immuno-gold particles and stereocilia links, both of only a few nanometers in diameter. We show that functional, mechanotransduction-mediating tip links have at least two molecular compositions, containing either PCDH15/CDH23 or PCDH15/PCDH15. During regeneration, shorter tip links containing nearly equal amounts of PCDH15 at both ends appear first. Whole-cell patch-clamp recordings demonstrate that these transient PCDH15/PCDH15 links mediate mechanotransduction currents of normal amplitude but abnormal Ca(2+)-dependent decay (adaptation). The mature PCDH15/CDH23 tip link composition is re-established later, concomitant with complete recovery of adaptation. Thus, our findings provide a molecular mechanism for regeneration and maintenance of mechanosensory function in postmitotic auditory hair cells and could help identify elusive components of the mechanotransduction machinery.
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Affiliation(s)
- Artur A. Indzhykulian
- Department of Physiology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Ruben Stepanyan
- Department of Physiology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Anastasiia Nelina
- Department of Physiology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Kateri J. Spinelli
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Zubair M. Ahmed
- Division of Pediatric Ophthalmology, Cincinnati Children's Research Foundation, Cincinnati, Ohio, United States of America
| | - Inna A. Belyantseva
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, Maryland, United States of America
| | - Thomas B. Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, Maryland, United States of America
| | - Peter G. Barr-Gillespie
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Gregory I. Frolenkov
- Department of Physiology, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail:
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62
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Herget M, Scheibinger M, Guo Z, Jan TA, Adams CM, Cheng AG, Heller S. A simple method for purification of vestibular hair cells and non-sensory cells, and application for proteomic analysis. PLoS One 2013; 8:e66026. [PMID: 23750277 PMCID: PMC3672136 DOI: 10.1371/journal.pone.0066026] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 05/07/2013] [Indexed: 11/23/2022] Open
Abstract
Mechanosensitive hair cells and supporting cells comprise the sensory epithelia of the inner ear. The paucity of both cell types has hampered molecular and cell biological studies, which often require large quantities of purified cells. Here, we report a strategy allowing the enrichment of relatively pure populations of vestibular hair cells and non-sensory cells including supporting cells. We utilized specific uptake of fluorescent styryl dyes for labeling of hair cells. Enzymatic isolation and flow cytometry was used to generate pure populations of sensory hair cells and non-sensory cells. We applied mass spectrometry to perform a qualitative high-resolution analysis of the proteomic makeup of both the hair cell and non-sensory cell populations. Our conservative analysis identified more than 600 proteins with a false discovery rate of <3% at the protein level and <1% at the peptide level. Analysis of proteins exclusively detected in either population revealed 64 proteins that were specific to hair cells and 103 proteins that were only detectable in non-sensory cells. Statistical analyses extended these groups by 53 proteins that are strongly upregulated in hair cells versus non-sensory cells and vice versa by 68 proteins. Our results demonstrate that enzymatic dissociation of styryl dye-labeled sensory hair cells and non-sensory cells is a valid method to generate pure enough cell populations for flow cytometry and subsequent molecular analyses.
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Affiliation(s)
- Meike Herget
- Department of Otolaryngology – HNS, Stanford University, Stanford, California, United States of America
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California, United States of America
| | - Mirko Scheibinger
- Department of Otolaryngology – HNS, Stanford University, Stanford, California, United States of America
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California, United States of America
| | - Zhaohua Guo
- Department of Otolaryngology – HNS, Stanford University, Stanford, California, United States of America
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California, United States of America
| | - Taha A. Jan
- Department of Otolaryngology – HNS, Stanford University, Stanford, California, United States of America
| | - Christopher M. Adams
- Mass Spectrometry Core, Stanford University, Stanford, California, United States of America
| | - Alan G. Cheng
- Department of Otolaryngology – HNS, Stanford University, Stanford, California, United States of America
| | - Stefan Heller
- Department of Otolaryngology – HNS, Stanford University, Stanford, California, United States of America
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California, United States of America
- * E-mail:
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63
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Noddy, a mouse harboring a missense mutation in protocadherin-15, reveals the impact of disrupting a critical interaction site between tip-link cadherins in inner ear hair cells. J Neurosci 2013; 33:4395-404. [PMID: 23467356 DOI: 10.1523/jneurosci.4514-12.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
In hair cells of the inner ear, sound or head movement increases tension in fine filaments termed tip links, which in turn convey force to mechanosensitive ion channels to open them. Tip links are formed by a tetramer of two cadherin proteins: protocadherin 15 (PCDH15) and cadherin 23 (CDH23), which have 11 and 27 extracellular cadherin (EC) repeats, respectively. Mutations in either protein cause inner ear disorders in mice and humans. We showed recently that these two cadherins bind tip-to-tip in a "handshake" mode that involves the EC1 and EC2 repeats of both proteins. However, a paucity of appropriate animal models has slowed our understanding both of the interaction and of how mutations of residues within the predicted interface compromise tip link integrity. Here, we present noddy, a new mouse model for hereditary deafness. Identified in a forward genetic screen, noddy homozygotes lack inner ear function. Mapping and sequencing showed that noddy mutant mice harbor an isoleucine-to-asparagine (I108N) mutation in the EC1 repeat of PCDH15. Residue I108 interacts with CDH23 EC2 in the handshake and its mutation impairs the interaction in vitro. The noddy mutation allowed us to determine the consequences of blocking the handshake in vivo: tip link formation and bundle morphology are disrupted, and mechanotransduction channels fail to remain open at rest. These results offer new insights into the interaction between PCDH15 and CDH23 and help explain the etiology of human deafness linked to mutations in the tip-link interface.
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Abstract
How mechanical forces are sensed remains largely mysterious. The forces that gate prokaryotic and several eukaryotic channels were found to come from the lipid membrane. Our survey of animal cells found that membrane force foci all have cholesterol-gathering proteins and are reinforced with cholesterol. This result is evident in overt force sensors at the tips of stereocilia for vertebrate hearing and the touch receptor of Caenorhabditis elegans and mammalian neurons. For less specialized cells, cadherins sustain the force between neighboring cells and integrins between cells and matrix. These tension bearers also pass through and bind to a cholesterol-enriched platform before anchoring to cytoskeleton through other proteins. Cholesterol, in alliance with sphingomyelin and specialized proteins, enforces a more ordered structure in the bilayer. Such a stiffened platform can suppress mechanical noise, redirect, rescale, and confine force. We speculate that such platforms may be dynamic. The applied force may allow disordered-phase lipids to enter the platform-staging channel opening in the thinner mobile neighborhood. The platform may also contain specialized protein/lipid subdomains enclosing mechanosensitive channels to open with localized tension. Such a dynamic stage can mechanically operate structurally disparate channels or enzymes without having to tie them directly to cadherin, integrin, or other protein tethers.
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Selvakumar D, Drescher MJ, Drescher DG. Cyclic nucleotide-gated channel α-3 (CNGA3) interacts with stereocilia tip-link cadherin 23 + exon 68 or alternatively with myosin VIIa, two proteins required for hair cell mechanotransduction. J Biol Chem 2013; 288:7215-29. [PMID: 23329832 DOI: 10.1074/jbc.m112.443226] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previously, we obtained evidence for a photoreceptor/olfactory type of CNGA3 transcript in a purified teleost vestibular hair cell preparation with immunolocalization of CNGA3 protein to stereocilia of teleost vestibular and mammalian cochlear hair cells. The carboxyl terminus of highly Ca(2+)-permeable CNGA3 expressed in the mammalian organ of Corti and saccular hair cells was found to interact with an intracellular domain of microfibril interface-located protein 1 (EMILIN 1), a member of the elastin superfamily, also immunolocalizd to hair cell stereocilia (Selvakumar, D., Drescher, M. J., Dowdall, J. R., Khan, K. M., Hatfield, J. S., Ramakrishnan, N. A., and Drescher, D. G. (2012) Biochem. J. 443, 463-476). Here, we provide evidence for organ of Corti proteins, of Ca(2+)-dependent binding of the amino terminus of CNGA3 specifically to the carboxyl terminus of stereocilia tip-link protein CDH23 +68 (cadherin 23 with expressed exon 68) by yeast two-hybrid mating and co-transformation protocols, pulldown assays, and surface plasmon resonance analysis. Myosin VIIa, required for adaptation of hair cell mechanotransduction (MET) channel(s), competed with CDH23 +68, with direct Ca(2+)-dependent binding to the amino terminus of CNGA3. Based upon the premise that hair cell stereocilia tip-link proteins are closely coupled with MET, these results are consistent with the possibility that CNGA3 participates in hair-cell MET. Together with the demonstration of protein-protein interaction between HCN1 and tip-link protein protocadherin 15 CD3 (Ramakrishnan, N. A., Drescher, M. J., Barretto, R. L., Beisel, K. W., Hatfield, J. S., and Drescher, D. G. (2009) J. Biol. Chem. 284, 3227-3238; Ramakrishnan, N. A., Drescher, M. J., Khan, K. M., Hatfield, J. S., and Drescher, D. G. (2012) J. Biol. Chem. 287, 37628-37646), a protein-protein interaction for CNGA3 and a second tip-link protein, CDH23 +68, further suggests possible association of two different channels with a single stereocilia tip link.
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Affiliation(s)
- Dakshnamurthy Selvakumar
- Laboratory of Bio-otology, Department of Otolaryngology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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66
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Cadherin defects in inherited human diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 116:361-84. [PMID: 23481203 DOI: 10.1016/b978-0-12-394311-8.00016-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The tight control of cell-cell connectivity mediated by cadherins is a key issue in human health and disease. The human genome contains over 115 genes encoding cadherins and cadherin-like proteins. Defects in about 21 of these proteins (8 classical, 5 desmosomal, 8 atypical cadherins) have been linked to inherited disorders in humans, including skin and hair disorders, cardiomyopathies, sensory defects associated with deafness and blindness, and psychiatric disorders. With the advent of exome and genome sequencing techniques, we can anticipate the discovery of yet more evidence for the involvement of additional cadherins. Elucidation of the related physiopathological mechanisms underlying these conditions should help to clarify the roles played by these cadherins in tissues and the ways in which defects in different cadherins cause such a wide spectrum of associated phenotypes. These disorders also constitute disparate model systems for investigations of the relative contributions of mechanical adhesive strength and intracellular signaling pathways to the pathogenic process for a given cadherin.
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Hackney CM, Furness DN. The composition and role of cross links in mechanoelectrical transduction in vertebrate sensory hair cells. J Cell Sci 2013; 126:1721-31. [DOI: 10.1242/jcs.106120] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The key components of acousticolateralis systems (lateral line, hearing and balance) are sensory hair cells. At their apex, these cells have a bundle of specialized cellular protrusions, which are modified actin-containing microvilli, connected together by extracellular filaments called cross links. Stereociliary deflections open nonselective cation channels allowing ions from the extracellular environment into the cell, a process called mechanoelectrical transduction. This produces a receptor potential that causes the release of the excitatory neurotransmitter glutamate onto the terminals of the sensory nerve fibres, which connect to the cell base, causing nerve signals to be sent to the brain. Identification of the cellular mechanisms underlying mechanoelectrical transduction and of some of the proteins involved has been assisted by research into the genetics of deafness, molecular biology and mechanical measurements of function. It is thought that one type of cross link, the tip link, is composed of cadherin 23 and protocadherin 15, and gates the transduction channel when the bundle is deflected. Another type of link, called lateral (or horizontal) links, maintains optimal bundle cohesion and stiffness for transduction. This Commentary summarizes the information currently available about the structure, function and composition of the links and how they might be relevant to human hearing impairment.
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Structure of a force-conveying cadherin bond essential for inner-ear mechanotransduction. Nature 2012; 492:128-32. [PMID: 23135401 PMCID: PMC3518760 DOI: 10.1038/nature11590] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 09/13/2012] [Indexed: 02/07/2023]
Abstract
Hearing and balance use hair cells in the inner ear to transform mechanical stimuli into electrical signals1. Mechanical force from sound waves or head movements is conveyed to hair-cell transduction channels by tip links2,3, fine filaments formed by two atypical cadherins: protocadherin-15 and cadherin-234,5. These two proteins are products of deafness genes6–10 and feature long extracellular domains that interact tip-to-tip5,11 in a Ca2+-dependent manner. However, the molecular architecture of the complex is unknown. Here we combine crystallography, molecular dynamics simulations, and binding experiments to characterize the cadherin-23 and protocadherin-15 bond. We find a unique cadherin interaction mechanism, with the two most N-terminal cadherin repeats (EC1+2) of each protein interacting to form an overlapped, antiparallel heterodimer. Simulations predict that this tip-link bond is mechanically strong enough to resist forces in hair cells. In addition, the complex becomes unstable upon Ca2+ removal due to increased flexure of Ca2+-free cadherin repeats. Finally, we use structures and biochemical measurements to understand molecular mechanisms by which deafness mutations disrupt tip-link function. Overall, our results shed light on the molecular mechanics of hair-cell sensory transduction and on new interaction mechanisms for cadherins, a large protein family implicated in tissue and organ morphogenesis12,13, neural connectivity14, and cancer15.
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Sahly I, Dufour E, Schietroma C, Michel V, Bahloul A, Perfettini I, Pepermans E, Estivalet A, Carette D, Aghaie A, Ebermann I, Lelli A, Iribarne M, Hardelin JP, Weil D, Sahel JA, El-Amraoui A, Petit C. Localization of Usher 1 proteins to the photoreceptor calyceal processes, which are absent from mice. ACTA ACUST UNITED AC 2012; 199:381-99. [PMID: 23045546 PMCID: PMC3471240 DOI: 10.1083/jcb.201202012] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mechanisms underlying retinal dystrophy in Usher syndrome type I (USH1) remain unknown because mutant mice lacking any of the USH1 proteins-myosin VIIa, harmonin, cadherin-23, protocadherin-15, sans-do not display retinal degeneration. We found here that, in macaque photoreceptor cells, all USH1 proteins colocalized at membrane interfaces (i) between the inner and outer segments in rods and (ii) between the microvillus-like calyceal processes and the outer segment basolateral region in rods and cones. This pattern, conserved in humans and frogs, was mediated by the formation of an USH1 protein network, which was associated with the calyceal processes from the early embryonic stages of outer segment growth onwards. By contrast, mouse photoreceptors lacked calyceal processes and had no USH1 proteins at the inner-outer segment interface. We suggest that USH1 proteins form an adhesion belt around the basolateral region of the photoreceptor outer segment in humans, and that defects in this structure cause the retinal degeneration in USH1 patients.
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Affiliation(s)
- Iman Sahly
- Institut de la vision, Syndrome de Usher et autres Atteintes Rétino-Cochléaires, 75012 Paris, France
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70
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Liu R, Wu F, Thiery JP. Remarkable disparity in mechanical response among the extracellular domains of type I and II cadherins. J Biomol Struct Dyn 2012; 31:1137-49. [PMID: 23034078 DOI: 10.1080/07391102.2012.726530] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Cadherins, a large family of calcium-dependent adhesion molecules, are critical for intercellular adhesion. While crystallographic structures for several cadherins show clear structural similarities, their relevant adhesive strengths vary and their mechanisms of adhesion between types I and II cadherin subfamilies are still unclear. Here, stretching of cadherins was explored experimentally by atomic force microscopy and computationally by steered molecular dynamics (SMD) simulations, where partial unfolding of the E-cadherin ectodomains was observed. The SMD simulations on strand-swapping cadherin dimers displayed similarity in binding strength, suggesting contributions of other mechanisms to explain the strength differences of cell adhesion in vivo. Systematic simulations on the unfolding of the extracellular domains of type I and II cadherins revealed diverse pathways. However, at the earliest stage, a remarkable similarity in unfolding was observed for the various type I cadherins that was distinct from that for type II cadherins. This likely correlates positively with their distinct adhesive properties, suggesting that the initial forced deformation in type I cadherins may be involved in cadherin-mediated adhesion. An animated Interactive 3D Complement (I3DC) is available in Proteopedia at http://proteopedia.org/w/Journal:JBSD:25.
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Affiliation(s)
- Ruchuan Liu
- a MechanoBiology Institute, National University of Singapore , 5A Engineering Drive 1 , 117411 , Singapore
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71
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Wu L, Pan L, Zhang C, Zhang M. Large protein assemblies formed by multivalent interactions between cadherin23 and harmonin suggest a stable anchorage structure at the tip link of stereocilia. J Biol Chem 2012; 287:33460-71. [PMID: 22879593 PMCID: PMC3460447 DOI: 10.1074/jbc.m112.378505] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 08/03/2012] [Indexed: 11/06/2022] Open
Abstract
Stereocilia tip links of inner ear hair cells are subjected to constant stretching during hair-bundle deflection, and accordingly are well designed to prevent from being broken by mechanical tensions. The roots of tip links, which couple tip links with the cytoskeleton, supposedly play important roles in withstanding large forces under stimulated conditions. The upper root of the tip link is mainly formed by the cytoplasmic tail of cadherin23 and its actin-anchoring protein harmonin. However, the detailed organization mode of the two proteins that gives rise to a strong upper root remains unclear. Here we show that the exon68-encoded peptide of cadherin23 can either interact with the N-terminal domain (NTD) of harmonin or form a homodimer. We demonstrate that the three harmonin binding sites of cadherin23, namely the NTD-binding motif, the exon68 peptide, and the C-terminal PDZ binding motif, do not synergize with each other in binding to harmonin, instead they facilitate formation of polymeric cadherin23/harmonin complexes. The exon68 peptide can promote the cadherin23/harmonin polymer formation via either binding to harmonin NTD or self-dimerization. We propose that the polymeric cadherin23/harmonin complex formed beneath the upper tip link membranes may serve as part of the stable rootlet structure for anchoring the tip links of stereocilia.
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Affiliation(s)
- Lin Wu
- From the Division of Life Science, State Key Laboratory of Molecular Neuroscience
| | - Lifeng Pan
- From the Division of Life Science, State Key Laboratory of Molecular Neuroscience
| | - Chuchu Zhang
- From the Division of Life Science, State Key Laboratory of Molecular Neuroscience
| | - Mingjie Zhang
- From the Division of Life Science, State Key Laboratory of Molecular Neuroscience
- Center of Systems Biology and Human Health, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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72
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Ceriani F, Mammano F. Calcium signaling in the cochlea - Molecular mechanisms and physiopathological implications. Cell Commun Signal 2012; 10:20. [PMID: 22788415 PMCID: PMC3408374 DOI: 10.1186/1478-811x-10-20] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 07/12/2012] [Indexed: 12/20/2022] Open
Abstract
Calcium ions (Ca2+) regulate numerous and diverse aspects of cochlear and vestibular physiology. This review focuses on the Ca2+ control of mechanotransduction and synaptic transmission in sensory hair cells, as well as on Ca2+ signalling in non-sensory cells of the developing cochlea.
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Affiliation(s)
- Federico Ceriani
- Dipartimento di Fisica e Astronomia "G, Galilei", Università di Padova, 35131, Padova, Italy.
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73
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Abstract
Cadherins are Ca(2+)-dependent cell-cell adhesion molecules that play critical roles in animal morphogenesis. Various cadherin-related molecules have also been identified, which show diverse functions, not only for the regulation of cell adhesion but also for that of cell proliferation and planar cell polarity. During the past decade, understanding of the roles of these molecules in the nervous system has significantly progressed. They are important not only for the development of the nervous system but also for its functions and, in turn, for neural disorders. In this review, we discuss the roles of cadherins and related molecules in neural development and function in the vertebrate brain.
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Affiliation(s)
- Shinji Hirano
- Department of Neurobiology and Anatomy, Kochi Medical School, Okoh-cho Kohasu, Nankoku-City 783–8505, Japan.
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74
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Parallel evolution of auditory genes for echolocation in bats and toothed whales. PLoS Genet 2012; 8:e1002788. [PMID: 22761589 PMCID: PMC3386236 DOI: 10.1371/journal.pgen.1002788] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Accepted: 05/12/2012] [Indexed: 11/24/2022] Open
Abstract
The ability of bats and toothed whales to echolocate is a remarkable case of convergent evolution. Previous genetic studies have documented parallel evolution of nucleotide sequences in Prestin and KCNQ4, both of which are associated with voltage motility during the cochlear amplification of signals. Echolocation involves complex mechanisms. The most important factors include cochlear amplification, nerve transmission, and signal re-coding. Herein, we screen three genes that play different roles in this auditory system. Cadherin 23 (Cdh23) and its ligand, protocadherin 15 (Pcdh15), are essential for bundling motility in the sensory hair. Otoferlin (Otof) responds to nerve signal transmission in the auditory inner hair cell. Signals of parallel evolution occur in all three genes in the three groups of echolocators—two groups of bats (Yangochiroptera and Rhinolophoidea) plus the dolphin. Significant signals of positive selection also occur in Cdh23 in the Rhinolophoidea and dolphin, and Pcdh15 in Yangochiroptera. In addition, adult echolocating bats have higher levels of Otof expression in the auditory cortex than do their embryos and non-echolocation bats. Cdh23 and Pcdh15 encode the upper and lower parts of tip-links, and both genes show signals of convergent evolution and positive selection in echolocators, implying that they may co-evolve to optimize cochlear amplification. Convergent evolution and expression patterns of Otof suggest the potential role of nerve and brain in echolocation. Our synthesis of gene sequence and gene expression analyses reveals that positive selection, parallel evolution, and perhaps co-evolution and gene expression affect multiple hearing genes that play different roles in audition, including voltage and bundle motility in cochlear amplification, nerve transmission, and brain function. The convergent origins of laryngeal echolocation in two groups of bats (Yangochiroptera and Rhinolophoidea) and toothed whales have long been a focus of interest for biologists. We screened three candidate genes—Cdh23, Pcdh15, and Otof—involved in different steps in the echolocation system. Signals of parallel evolution occurred in all three genes in the three groups of echolocators. Cdh23 and Pcdh15 constitute part of the mechanical link within the hair bundle of the ear. Both genes showed signals of both convergent evolution and positive selection, which implied they may have co-evolved to optimize cochlear amplification. Further, three lines of evidence suggest that Otof plays an important role in the transmission of signals in the brain during echolocation. First, the gene is more highly expressed in the auditory cortex of the brain in echolocating adult bats than in other cerebral cortexes. Second, this expression is higher in adult echolocating female bats than in their embryos, which do not use echolocation. Third, echolocators also have a higher level of expression in their cerebral cortexes than do non-echolocating bats. Taken with other evidence, the independent origins of echolocation involve the same genes that have evolved in precisely identical ways.
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75
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Powers RJ, Roy S, Atilgan E, Brownell WE, Sun SX, Gillespie PG, Spector AA. Stereocilia membrane deformation: implications for the gating spring and mechanotransduction channel. Biophys J 2012; 102:201-10. [PMID: 22339856 DOI: 10.1016/j.bpj.2011.12.022] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 11/29/2011] [Accepted: 12/05/2011] [Indexed: 11/30/2022] Open
Abstract
In hair cells, although mechanotransduction channels have been localized to tips of shorter stereocilia of the mechanically sensitive hair bundle, little is known about how force is transmitted to the channel. Here, we use a biophysical model of the membrane-channel complex to analyze the nature of the gating spring compliance and channel arrangement. We use a triangulated surface model and Monte Carlo simulation to compute the deformation of the membrane under the action of tip link force. We show that depending on the gating spring stiffness, the compliant component of the gating spring arises from either the membrane alone or a combination of the membrane and a tether that connects the channel to the actin cytoskeleton. If a bundle is characterized by relatively soft gating springs, such as those of the bullfrog sacculus, the need for membrane reinforcement by channel tethering then depends on membrane parameters. With stiffer gating springs, such as those from rat outer hair cells, the channel must be tethered for all biophysically realistic parameters of the membrane. We compute the membrane forces (resultants), which depend on membrane tension, bending modulus, and curvature, and show that they can determine the fate of the channel.
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Affiliation(s)
- Richard J Powers
- Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, Maryland, USA
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76
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Pan L, Zhang M. Structures of usher syndrome 1 proteins and their complexes. Physiology (Bethesda) 2012; 27:25-42. [PMID: 22311968 DOI: 10.1152/physiol.00037.2011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Usher syndrome 1 (USH1) is the most common and severe form of hereditary loss of hearing and vision. Genetic, physiological, and cell biological studies, together with recent structural investigations, have not only uncovered the physiological functions of the five USH1 proteins but also provided mechanistic explanations for the hearing and visual deficiencies in humans caused by USH1 mutations. This review focuses on the structural basis of the USH1 protein complex organization.
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Affiliation(s)
- Lifeng Pan
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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77
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Giacomello M, De Mario A, Primerano S, Brini M, Carafoli E. Hair cells, plasma membrane Ca2+ ATPase and deafness. Int J Biochem Cell Biol 2012; 44:679-83. [DOI: 10.1016/j.biocel.2012.02.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 01/24/2012] [Accepted: 02/03/2012] [Indexed: 11/29/2022]
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78
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Brasch J, Harrison OJ, Honig B, Shapiro L. Thinking outside the cell: how cadherins drive adhesion. Trends Cell Biol 2012; 22:299-310. [PMID: 22555008 DOI: 10.1016/j.tcb.2012.03.004] [Citation(s) in RCA: 242] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 03/19/2012] [Accepted: 03/26/2012] [Indexed: 12/15/2022]
Abstract
Cadherins are a superfamily of cell surface glycoproteins whose ectodomains contain multiple repeats of β-sandwich extracellular cadherin (EC) domains that adopt a similar fold to immunoglobulin domains. The best characterized cadherins are the vertebrate 'classical' cadherins, which mediate adhesion via trans homodimerization between their membrane-distal EC1 domains that extend from apposed cells, and assemble intercellular adherens junctions through cis clustering. To form mature trans adhesive dimers, cadherin domains from apposed cells dimerize in a 'strand-swapped' conformation. This occurs in a two-step binding process involving a fast-binding intermediate called the 'X-dimer'. Trans dimers are less flexible than cadherin monomers, a factor that drives junction assembly following cell-cell contact by reducing the entropic cost associated with the formation of lateral cis oligomers. Cadherins outside the classical subfamily appear to have evolved distinct adhesive mechanisms that are only now beginning to be understood.
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Affiliation(s)
- Julia Brasch
- Department of Biochemistry and Molecular Biophysics, Columbia University, 1150 Saint Nicholas Avenue, New York, NY 10032, USA
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79
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Apostolopoulou M, Ligon L. Cadherin-23 mediates heterotypic cell-cell adhesion between breast cancer epithelial cells and fibroblasts. PLoS One 2012; 7:e33289. [PMID: 22413011 PMCID: PMC3296689 DOI: 10.1371/journal.pone.0033289] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 02/13/2012] [Indexed: 12/31/2022] Open
Abstract
In the early stages of breast cancer metastasis, epithelial cells penetrate the basement membrane and invade the surrounding stroma, where they encounter fibroblasts. Paracrine signaling between fibroblasts and epithelial tumor cells contributes to the metastatic cascade, but little is known about the role of adhesive contacts between these two cell types in metastasis. Here we show that MCF-7 breast cancer epithelial cells and normal breast fibroblasts form heterotypic adhesions when grown together in co-culture, as evidenced by adhesion assays. PCR and immunoblotting show that both cell types express multiple members of the cadherin superfamily, including the atypical cadherin, cadherin-23, when grown in isolation and in co-culture. Immunocytochemistry experiments show that cadherin-23 localizes to homotypic adhesions between MCF-7 cells and also to heterotypic adhesions between the epithelial cells and fibroblasts, and antibody inhibition and RNAi experiments show that cadherin-23 plays a role in mediating these adhesive interactions. Finally, we show that cadherin-23 is upregulated in breast cancer tissue samples, and we hypothesize that heterotypic adhesions mediated by this atypical cadherin may play a role in the early stages of metastasis.
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Affiliation(s)
- Maria Apostolopoulou
- Department of Biology and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, United States of America
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80
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Anomalous Brownian motion discloses viscoelasticity in the ear's mechanoelectrical-transduction apparatus. Proc Natl Acad Sci U S A 2012; 109:2896-901. [PMID: 22328158 DOI: 10.1073/pnas.1121389109] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ear detects sounds so faint that they produce only atomic-scale displacements in the mechanoelectrical transducer, yet thermal noise causes fluctuations larger by an order of magnitude. Explaining how hearing can operate when the magnitude of the noise greatly exceeds that of the signal requires an understanding both of the transducer's micromechanics and of the associated noise. Using microrheology, we characterize the statistics of this noise; exploiting the fluctuation-dissipation theorem, we determine the associated micromechanics. The statistics reveal unusual Brownian motion in which the mean square displacement increases as a fractional power of time, indicating that the mechanisms governing energy dissipation are related to those of energy storage. This anomalous scaling contradicts the canonical model of mechanoelectrical transduction, but the results can be explained if the micromechanics incorporates viscoelasticity, a salient characteristic of biopolymers. We amend the canonical model and demonstrate several consequences of viscoelasticity for sensory coding.
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81
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A mutation in the cdh23 gene causes age-related hearing loss in Cdh23(nmf308/nmf308) mice. Gene 2012; 499:309-17. [PMID: 22326520 DOI: 10.1016/j.gene.2012.01.084] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 01/26/2012] [Accepted: 01/29/2012] [Indexed: 01/11/2023]
Abstract
Cadherin 23 (CDH23) is an important constituent of the hair cell tip link in the organ of Corti. Mutations in cdh23 are associated with age-related hearing loss (AHL). In this study, we proposed that the Cdh23(nmf308/nmf308) mice with progressive hair cell loss had specific morphological changes and suffered a base to apex gradient and age-related hearing loss, and that mutations in cdh23 were linked to AHL. The Cdh23(nmf308/nmf308) mice produced by the N-nitrosourea (ENU) mutagenesis program were used as an animal model to study AHL and progressive hair cell loss. RT-PCR was performed to confirm the cdh23 mutation in Cdh23(nmf308/nmf308) mice and genetic analysis was used to map the specific mutation site. Distortion product otoacoustic emission (DPOAE) assay and acoustic brainstem evoked response (ABR) threshold analysis were carried out to evaluate the AHL. Cochlear histology was examined with scanning electron microscope (SEM) and transmission electron microscope (TEM), as well as the nuclear labeling by propidium iodide staining; terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assay and caspase-3 activities were examined to evaluate cell apoptosis. Genetic mapping identified the candidate gene linking AHL in Cdh23(nmf308/nmf308) mice as cdh23. A mutation in exon3 (63 T>C) was screened as compared with the sequence of the same position of the gene from B6 (+/+) mice. The cochleae outer hair cells were reduced from 5-10% at one month to 100% at three months in the basal region. DPOAE and ABR exhibited an increasing threshold at high frequencies (≥16kHz) from one month of age. Morphological and cellular analysis showed that Cdh23(nmf308/nmf308) mice exhibited a time course of histological alterations and cell apoptosis of outer hair cells. Our results suggest that the cdh23 mutation may be harmful to the stereociliary tip link and cause the hair cell apoptosis. Due to the same cdh23 mutations in human subjects with presbycusis (Petit et al., 2001; Zheng et al., 2005), the Cdh23(nmf308/nmf308) mouse is an excellent animal model for investigating the mechanisms involved in human AHL.
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82
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Kazmierczak P, Müller U. Sensing sound: molecules that orchestrate mechanotransduction by hair cells. Trends Neurosci 2011; 35:220-9. [PMID: 22177415 DOI: 10.1016/j.tins.2011.10.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 10/25/2011] [Accepted: 10/27/2011] [Indexed: 01/19/2023]
Abstract
Animals use acoustic signals to communicate and to obtain information about their environment. The processing of acoustic signals is initiated at auditory sense organs, where mechanosensory hair cells convert sound-induced vibrations into electrical signals. Although the biophysical principles underlying the mechanotransduction process in hair cells have been characterized in much detail over the past 30 years, the molecular building-blocks of the mechanotransduction machinery have proved to be difficult to determine. We review here recent studies that have both identified some of these molecules and established the mechanisms by which they regulate the activity of the still-elusive mechanotransduction channel.
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Affiliation(s)
- Piotr Kazmierczak
- Dorris Neuroscience Center, Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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83
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Bryda EC, Johnson NT, Ohlemiller KK, Besch-Williford CL, Moore E, Bram RJ. Conditional deletion of calcium-modulating cyclophilin ligand causes deafness in mice. Mamm Genome 2011; 23:270-6. [PMID: 22170629 DOI: 10.1007/s00335-011-9381-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 11/24/2011] [Indexed: 12/18/2022]
Abstract
Calcium-modulating cyclophilin ligand (Caml) is a ubiquitously expressed cytoplasmic protein that is involved in multiple signaling and developmental pathways. An observation in our laboratory of a protein-protein interaction between Caml and the cytoplasmic region of Cadherin23 led us to speculate that Caml might be important in the inner ear and play a role in the development and/or function of hair cells. To address this question, we generated a mouse line in which Caml expression was eliminated in Atoh1-expressing cells of the inner ear upon administration of tamoxifen. Tamoxifen was administered immediately after birth to neonates to assess the effect of loss of Caml in the inner ear during postnatal development. Hearing in treated animals was tested by auditory brain stem response (ABR) analysis and cochlear pathology was evaluated by light microscopy. Lack of Caml expression in the inner ear leads to severe loss of cochlear hair cells and complete deafness. Elucidating the role of Caml in the inner ear will aid our understanding of the molecular pathways important for auditory development and function.
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Affiliation(s)
- Elizabeth C Bryda
- Research Animal Diagnostic Laboratory, Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, 4011 Discovery Drive, Columbia, MO 65201, USA.
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84
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Integrating the biophysical and molecular mechanisms of auditory hair cell mechanotransduction. Nat Commun 2011; 2:523. [PMID: 22045002 DOI: 10.1038/ncomms1533] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Mechanosensation is a primitive and somewhat ubiquitous sense. At the inner ear, sensory hair cells are refined to enhance sensitivity, dynamic range and frequency selectivity. Thirty years ago, mechanisms of mechanotransduction and adaptation were well accounted for by simple mechanical models that incorporated physiological and morphological properties of hair cells. Molecular and genetic tools, coupled with new optical techniques, are now identifying and localizing specific components of the mechanotransduction machinery. These new findings challenge long-standing theories, and require modification of old and development of new models. Future advances require the integration of molecular and physiological data to causally test these new hypotheses.
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85
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Carafoli E. The plasma membrane calcium pump in the hearing process: physiology and pathology. SCIENCE CHINA-LIFE SCIENCES 2011; 54:686-90. [PMID: 21786191 DOI: 10.1007/s11427-011-4200-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Accepted: 06/22/2011] [Indexed: 10/18/2022]
Abstract
Mammalian cells express four different plasma membrane Ca(2+) ATPases. Two of them (PMCA1 and PMCA4) are expressed ubiquitously, and are considered housekeeping isoforms. Two (PMCA2 and PMCA4) have tissue restricted distribution. They are abundantly expressed in the brain and in nervous tissue-derived cell types. The primary transcripts of all PMCAs undergo alternative splicing, generating a large number of additional isoforms. Splicing occurs at site A, in the N-terminal moiety of the pump, and at site C, within the C-terminal calmodulin binding domain: The pumps are canonical targets of calmodulin stimulation. The site C insertion leads to a truncation of the pump about 50 residues short of the original C-terminal. One of the pumps (PMCA2) has special properties: It displays high activity even in the absence of the natural activator calmodulin, and has a particularly complex pattern of alternative splicing at both sites A and C. A variant of the PMCA2 pump containing an insert at site A and truncated C-terminally is the resident isoform of the pump in the stereocilia of hair cells of the inner ear. It exports Ca(2+) to the endolymph that bathes the stereocilia less efficiently than the full length, non-inserted PMCA2 pump. The proper functioning of hair cells demands the precise maintenance of the Ca(2+) balance between hair cells and the endolymph. Disturbances in the balance affect the process of mechano-electrical transduction, which depends on the ability of the stereociliar bundle to deflect in response to sound waves. The tip links that organize the bundle are formed by the Ca(2+) binding protein cadherin 23 and by protocadherin 15: Disturbances of the Ca(2+) binding by cadherin 23 and/or of the ability of the PMCA2 variant of the stereocilia to export Ca(2+) to the endolymph generate hearing loss phenotypes. Such phenotypes have now been described in mice and humans. In some cases they are linked to mutations of both cadherin 23 and the PMCA2 pump, but in other cases they may be generated by mutations of particular severity in only one of the two proteins. The PMCA2 defect that leads to deafness has now been analyzed molecularly: It affects the long range, unstimulated ability of PMCA2 to export Ca(2+).
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Affiliation(s)
- Ernesto Carafoli
- Venetian Institute of Molecular Medicine, University of Padova, Padua, Italy.
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86
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Auditory and vestibular hair cell stereocilia: relationship between functionality and inner ear disease. The Journal of Laryngology & Otology 2011; 125:991-1003. [PMID: 21774850 DOI: 10.1017/s0022215111001459] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The stereocilia of the inner ear are unique cellular structures which correlate anatomically with distinct cochlear functions, including mechanoelectrical transduction, cochlear amplification, adaptation, frequency selectivity and tuning. Their function is impaired by inner ear stressors, by various types of hereditary deafness, syndromic hearing loss and inner ear disease (e.g. Ménière's disease). The anatomical and physiological characteristics of stereocilia are discussed in relation to inner ear malfunctions.
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87
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Manji SSM, Miller KA, Williams LH, Andreasen L, Siboe M, Rose E, Bahlo M, Kuiper M, Dahl HHM. An ENU-induced mutation of Cdh23 causes congenital hearing loss, but no vestibular dysfunction, in mice. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:903-14. [PMID: 21689626 DOI: 10.1016/j.ajpath.2011.04.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 03/29/2011] [Accepted: 04/25/2011] [Indexed: 11/29/2022]
Abstract
Mutations in the human cadherin 23 (CDH23) gene cause deafness, neurosensory, autosomal recessive 12 (DFNB12) nonsyndromic hearing loss or Usher syndrome, type 1D (characterized by hearing impairment, vestibular dysfunction, and visual impairment). Reported waltzer mouse strains each harbor a Cdh23-null mutation and present with hearing loss and vestibular dysfunction. Two additional Cdh23 mouse mutants, salsa and erlong, each carry a homozygous Cdh23 missense mutation and have progressive hearing loss. We report the identification of a novel mouse strain, jera, with inherited hearing loss caused by an N-ethyl-N-nitrosourea-induced c.7079T>A mutation in the Cdh23 gene. The mutation generates a missense change, p.V2360E, in Cdh23. Affected mice have profound sensorineural deafness, with no vestibular dysfunction. The p.V2360E mutation is semidominant because heterozygous mice have milder and more progressive hearing loss in advanced age. The mutation affects a highly conserved Ca(2+)-binding motif in extracellular domain 22, thought to be important for Cdh23 structure and dimerization. Molecular modeling suggests that the Cdh23(V2360E/V2360E) mutation alters the structural conformation of the protein and affects Ca(2+)-binding properties. Similar to salsa mice, but in contrast to waltzer mice, hair bundle development is normal in jera and hearing loss appears to be due to the loss of tip links. Thus, jera is a novel mouse model for DFNB12.
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Affiliation(s)
- Shehnaaz S M Manji
- Genetic Hearing Research Laboratory, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia.
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88
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Bonnet C, Grati M, Marlin S, Levilliers J, Hardelin JP, Parodi M, Niasme-Grare M, Zelenika D, Délépine M, Feldmann D, Jonard L, El-Amraoui A, Weil D, Delobel B, Vincent C, Dollfus H, Eliot MM, David A, Calais C, Vigneron J, Montaut-Verient B, Bonneau D, Dubin J, Thauvin C, Duvillard A, Francannet C, Mom T, Lacombe D, Duriez F, Drouin-Garraud V, Thuillier-Obstoy MF, Sigaudy S, Frances AM, Collignon P, Challe G, Couderc R, Lathrop M, Sahel JA, Weissenbach J, Petit C, Denoyelle F. Complete exon sequencing of all known Usher syndrome genes greatly improves molecular diagnosis. Orphanet J Rare Dis 2011; 6:21. [PMID: 21569298 PMCID: PMC3125325 DOI: 10.1186/1750-1172-6-21] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2010] [Accepted: 05/11/2011] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Usher syndrome (USH) combines sensorineural deafness with blindness. It is inherited in an autosomal recessive mode. Early diagnosis is critical for adapted educational and patient management choices, and for genetic counseling. To date, nine causative genes have been identified for the three clinical subtypes (USH1, USH2 and USH3). Current diagnostic strategies make use of a genotyping microarray that is based on the previously reported mutations. The purpose of this study was to design a more accurate molecular diagnosis tool. METHODS We sequenced the 366 coding exons and flanking regions of the nine known USH genes, in 54 USH patients (27 USH1, 21 USH2 and 6 USH3). RESULTS Biallelic mutations were detected in 39 patients (72%) and monoallelic mutations in an additional 10 patients (18.5%). In addition to biallelic mutations in one of the USH genes, presumably pathogenic mutations in another USH gene were detected in seven patients (13%), and another patient carried monoallelic mutations in three different USH genes. Notably, none of the USH3 patients carried detectable mutations in the only known USH3 gene, whereas they all carried mutations in USH2 genes. Most importantly, the currently used microarray would have detected only 30 of the 81 different mutations that we found, of which 39 (48%) were novel. CONCLUSIONS Based on these results, complete exon sequencing of the currently known USH genes stands as a definite improvement for molecular diagnosis of this disease, which is of utmost importance in the perspective of gene therapy.
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Affiliation(s)
- Crystel Bonnet
- Unité de Génétique Médicale, INSERM UMRS 587, Hôpital d'Enfants Armand-Trousseau, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France
- Unité de Génétique et Physiologie de l'Audition, INSERM UMRS 587, UPMC, Institut Pasteur, Paris, France
| | - M'hamed Grati
- Unité de Génétique Médicale, INSERM UMRS 587, Hôpital d'Enfants Armand-Trousseau, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France
- Unité de Génétique et Physiologie de l'Audition, INSERM UMRS 587, UPMC, Institut Pasteur, Paris, France
- NIDCD, NIH, Bethesda, MD 20894, USA
| | - Sandrine Marlin
- Unité de Génétique Médicale, INSERM UMRS 587, Hôpital d'Enfants Armand-Trousseau, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France
| | - Jacqueline Levilliers
- Unité de Génétique et Physiologie de l'Audition, INSERM UMRS 587, UPMC, Institut Pasteur, Paris, France
| | - Jean-Pierre Hardelin
- Unité de Génétique et Physiologie de l'Audition, INSERM UMRS 587, UPMC, Institut Pasteur, Paris, France
| | - Marine Parodi
- Service de Biochimie et de Biologie Moléculaire, INSERM UMRS 587, Hôpital d'Enfants Armand-Trousseau, AP-HP, Paris, France
| | - Magali Niasme-Grare
- Service de Biochimie et de Biologie Moléculaire, INSERM UMRS 587, Hôpital d'Enfants Armand-Trousseau, AP-HP, Paris, France
| | | | | | - Delphine Feldmann
- Unité de Génétique Médicale, INSERM UMRS 587, Hôpital d'Enfants Armand-Trousseau, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France
- Service de Biochimie et de Biologie Moléculaire, INSERM UMRS 587, Hôpital d'Enfants Armand-Trousseau, AP-HP, Paris, France
| | - Laurence Jonard
- Unité de Génétique Médicale, INSERM UMRS 587, Hôpital d'Enfants Armand-Trousseau, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France
- Service de Biochimie et de Biologie Moléculaire, INSERM UMRS 587, Hôpital d'Enfants Armand-Trousseau, AP-HP, Paris, France
| | - Aziz El-Amraoui
- Unité de Génétique et Physiologie de l'Audition, INSERM UMRS 587, UPMC, Institut Pasteur, Paris, France
| | - Dominique Weil
- Unité de Génétique et Physiologie de l'Audition, INSERM UMRS 587, UPMC, Institut Pasteur, Paris, France
| | - Bruno Delobel
- Centre de Génétique, Hôpital St-Antoine, Lille, France
| | | | - Hélène Dollfus
- Service de Génétique médicale, Hôpital de Hautepierre, Strasbourg, France
| | | | - Albert David
- Service de Génétique, Hôtel Dieu, Nantes, France
| | | | | | | | - Dominique Bonneau
- Centre de Référence des Maladies Neurogénétiques, Centre Hospitalier Universitaire d'Angers, France
| | - Jacques Dubin
- Service ORL, Centre Hospitalier Universitaire d'Angers, France
| | | | | | | | - Thierry Mom
- Service ORL, Hôtel-Dieu, Clermont-Ferrand, France
| | - Didier Lacombe
- Centre de Génétique, Hôpital Pellegrin, Bordeaux, France
| | | | | | | | - Sabine Sigaudy
- Service de Génétique Médicale, Hôpital de la Timone, Marseille, France
| | - Anne-Marie Frances
- Service de Génétique Médicale, Hôpital intercommunal de Font-Pré, Toulon La Seyne sur Mer, France
| | - Patrick Collignon
- Service de Génétique Médicale, Hôpital intercommunal de Font-Pré, Toulon La Seyne sur Mer, France
| | - Georges Challe
- Departement d'Ophtalmologie et de Médecine Interne, Hôpital de la Salpêtrière, AP-HP, France
| | - Rémy Couderc
- Unité de Génétique Médicale, INSERM UMRS 587, Hôpital d'Enfants Armand-Trousseau, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France
- Service de Biochimie et de Biologie Moléculaire, INSERM UMRS 587, Hôpital d'Enfants Armand-Trousseau, AP-HP, Paris, France
| | - Mark Lathrop
- Centre National de Génotypage, CEA, Evry, France
| | | | - Jean Weissenbach
- CEA, DSV, IG, Genoscope, CNRS-UMR 8030, UEVE, Université d'Evry, Evry, France
| | - Christine Petit
- Unité de Génétique et Physiologie de l'Audition, INSERM UMRS 587, UPMC, Institut Pasteur, Paris, France
- Collège de France, Paris, France
| | - Françoise Denoyelle
- Unité de Génétique et Physiologie de l'Audition, INSERM UMRS 587, UPMC, Institut Pasteur, Paris, France
- Service d'ORL et de Chirurgie Cervico-faciale, INSERM UMRS 587, Hôpital d'Enfants Armand-Trousseau, AP-HP, UPMC, Paris, France
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Abstract
Ca(2+) acts as a fundamental signal transduction element in inner ear, delivering information about sound, acceleration and gravity through a small number of mechanotransduction channels in the hair cell stereocilia and voltage activated Ca(2+) channels at the ribbon synapse, where it drives neurotransmission. The mechanotransduction process relies on the endocochlear potential, an electrical potential difference between endolymph and perilymph, the two fluids bathing respectively the apical and basolateral membrane of the cells in the organ of Corti. In mouse models, deafness and lack or reduction of the endocochlear potential correlate with ablation of connexin (Cx) 26 or 30. These Cxs form heteromeric channels assembled in a network of gap junction plaques connecting the supporting and epithelial cells of the organ of Corti presumably for K(+) recycle and transfer of key metabolites, for example, the Ca(2+) -mobilizing second messenger IP(3) . Ca(2+) signaling in these cells could play a crucial role in regulating Cx expression and function. Another district where Ca(2+) signaling alterations link to hearing loss is hair cell apex, where ablation or missense mutations of the PMCA2 Ca(2+) -pump of the stereocilia cause deafness and loss of balance. If less Ca(2+) is exported from the stereocilia, as in the PMCA2 mouse mutants, Ca(2+) concentration in endolymph is expected to fall causing an alteration of the mechanotransduction process. This may provide a clue as to why, in some cases, PMCA2 mutations potentiated the deafness phenotype induced by coexisting mutations of cadherin-23 (Usher syndrome type 1D), a single pass membrane Ca(2+) binding protein that is abundantly expressed in the stereocilia.
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Affiliation(s)
- Fabio Mammano
- Department of Physics "G. Galilei," University of Padova, Italy.
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90
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Alagramam KN, Goodyear RJ, Geng R, Furness DN, van Aken AFJ, Marcotti W, Kros CJ, Richardson GP. Mutations in protocadherin 15 and cadherin 23 affect tip links and mechanotransduction in mammalian sensory hair cells. PLoS One 2011; 6:e19183. [PMID: 21532990 PMCID: PMC3080917 DOI: 10.1371/journal.pone.0019183] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Accepted: 03/29/2011] [Indexed: 11/26/2022] Open
Abstract
Immunocytochemical studies have shown that protocadherin-15 (PCDH15) and cadherin-23 (CDH23) are associated with tip links, structures thought to gate the mechanotransducer channels of hair cells in the sensory epithelia of the inner ear. The present report describes functional and structural analyses of hair cells from Pcdh15av3J (av3J), Pcdh15av6J (av6J) and Cdh23v2J (v2J) mice. The av3J and v2J mice carry point mutations that are predicted to introduce premature stop codons in the transcripts for Pcdh15 and Cdh23, respectively, and av6J mice have an in-frame deletion predicted to remove most of the 9th cadherin ectodomain from PCDH15. Severe disruption of hair-bundle morphology is observed throughout the early-postnatal cochlea in av3J/av3J and v2J/v2J mice. In contrast, only mild-to-moderate bundle disruption is evident in the av6J/av6J mice. Hair cells from av3J/av3J mice are unaffected by aminoglycosides and fail to load with [3H]-gentamicin or FM1-43, compounds that permeate the hair cell's mechanotransducer channels. In contrast, hair cells from av6J/av6J mice load with both FM1-43 and [3H]-gentamicin, and are aminoglycoside sensitive. Transducer currents can be recorded from hair cells of all three mutants but are reduced in amplitude in all mutants and have abnormal directional sensitivity in the av3J/av3J and v2J/v2J mutants. Scanning electron microscopy of early postnatal cochlear hair cells reveals tip-link like links in av6J/av6J mice, substantially reduced numbers of links in the av3J/av3J mice and virtually none in the v2J/v2J mice. Analysis of mature vestibular hair bundles reveals an absence of tip links in the av3J/av3J and v2J/v2J mice and a reduction in av6J/av6J mice. These results therefore provide genetic evidence consistent with PCDH15 and CDH23 being part of the tip-link complex and necessary for normal mechanotransduction.
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Affiliation(s)
- Kumar N. Alagramam
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Richard J. Goodyear
- School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom
| | - Ruishuang Geng
- Otolaryngology Head and Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - David N. Furness
- Institute for Science and Technology in Medicine, School of Life Sciences, Keele University, Staffordshire, United Kingdom
| | | | - Walter Marcotti
- School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom
| | - Corné J. Kros
- School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom
- * E-mail: (CJK); (GPR)
| | - Guy P. Richardson
- School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom
- * E-mail: (CJK); (GPR)
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91
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Oroz J, Valbuena A, Vera AM, Mendieta J, Gómez-Puertas P, Carrión-Vázquez M. Nanomechanics of the cadherin ectodomain: "canalization" by Ca2+ binding results in a new mechanical element. J Biol Chem 2011; 286:9405-18. [PMID: 21177864 PMCID: PMC3058956 DOI: 10.1074/jbc.m110.170399] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 12/13/2010] [Indexed: 11/06/2022] Open
Abstract
Cadherins form a large family of calcium-dependent cell-cell adhesion receptors involved in development, morphogenesis, synaptogenesis, differentiation, and carcinogenesis through signal mechanotransduction using an adaptor complex that connects them to the cytoskeleton. However, the molecular mechanisms underlying mechanotransduction through cadherins remain unknown, although their extracellular region (ectodomain) is thought to be critical in this process. By single molecule force spectroscopy, molecular dynamics simulations, and protein engineering, here we have directly examined the nanomechanics of the C-cadherin ectodomain and found it to be strongly dependent on the calcium concentration. In the presence of calcium, the ectodomain extends through a defined ("canalized") pathway that involves two mechanical resistance elements: a mechanical clamp from the cadherin domains and a novel mechanostable component from the interdomain calcium-binding regions ("calcium rivet") that is abolished by magnesium replacement and in a mutant intended to impede calcium coordination. By contrast, in the absence of calcium, the mechanical response of the ectodomain becomes largely "decanalized" and destabilized. The cadherin ectodomain may therefore behave as a calcium-switched "mechanical antenna" with very different mechanical responses depending on calcium concentration (which would affect its mechanical integrity and force transmission capability). The versatile mechanical design of the cadherin ectodomain and its dependence on extracellular calcium facilitate a variety of mechanical responses that, we hypothesize, could influence the various adhesive properties mediated by cadherins in tissue morphogenesis, synaptic plasticity, and disease. Our work represents the first step toward the mechanical characterization of the cadherin system, opening the door to understanding the mechanical bases of its mechanotransduction.
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Affiliation(s)
- Javier Oroz
- From the Instituto Cajal/Consejo Superior de Investigaciones Científicas (CSIC), Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), and Instituto Madrileño de Estudios Avanzados (IMDEA) Nanociencia, Avenida Doctor Arce 37, E-28002 Madrid, Spain
| | - Alejandro Valbuena
- From the Instituto Cajal/Consejo Superior de Investigaciones Científicas (CSIC), Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), and Instituto Madrileño de Estudios Avanzados (IMDEA) Nanociencia, Avenida Doctor Arce 37, E-28002 Madrid, Spain
| | - Andrés Manuel Vera
- From the Instituto Cajal/Consejo Superior de Investigaciones Científicas (CSIC), Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), and Instituto Madrileño de Estudios Avanzados (IMDEA) Nanociencia, Avenida Doctor Arce 37, E-28002 Madrid, Spain
| | - Jesús Mendieta
- Centro de Biología Molecular Severo Ochoa, CSIC-Universidad Autónoma de Madrid, E-28049 Madrid, Spain, and
- Biomol-Informatics SL, E-28049 Madrid, Spain
| | - Paulino Gómez-Puertas
- Centro de Biología Molecular Severo Ochoa, CSIC-Universidad Autónoma de Madrid, E-28049 Madrid, Spain, and
| | - Mariano Carrión-Vázquez
- From the Instituto Cajal/Consejo Superior de Investigaciones Científicas (CSIC), Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), and Instituto Madrileño de Estudios Avanzados (IMDEA) Nanociencia, Avenida Doctor Arce 37, E-28002 Madrid, Spain
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Richardson GP, de Monvel JB, Petit C. How the Genetics of Deafness Illuminates Auditory Physiology. Annu Rev Physiol 2011; 73:311-34. [DOI: 10.1146/annurev-physiol-012110-142228] [Citation(s) in RCA: 171] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Guy P. Richardson
- School of Life Sciences, University of Sussex, Brighton, BN1 9QG, United Kingdom;
| | - Jacques Boutet de Monvel
- Unité de Génétique et Physiologie de l'Audition, Département de Neuroscience, Institut Pasteur, F-75724 Paris cedex 15, France; ,
- Inserm UMRS 587, F-75015 Paris, France
- Université Pierre & Marie Curie, F-75005 Paris, France
| | - Christine Petit
- Unité de Génétique et Physiologie de l'Audition, Département de Neuroscience, Institut Pasteur, F-75724 Paris cedex 15, France; ,
- Inserm UMRS 587, F-75015 Paris, France
- Université Pierre & Marie Curie, F-75005 Paris, France
- Collège de France, F-75005 Paris, France
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Development and regeneration of sensory transduction in auditory hair cells requires functional interaction between cadherin-23 and protocadherin-15. J Neurosci 2010; 30:11259-69. [PMID: 20739546 DOI: 10.1523/jneurosci.1949-10.2010] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Tip links are extracellular filaments that connect pairs of hair cell stereocilia and convey tension to mechanosensitive channels. Recent evidence suggests that tip links are formed by calcium-dependent interactions between the N-terminal domains of cadherin-23 (CDH23) and protocadherin-15 (PCDH15). Mutations in either CDH23 or PCDH15 cause deafness in mice and humans, indicating the molecules are required for normal inner ear function. However, there is little physiological evidence to support a direct role for CDH23 and PCDH15 in hair cell mechanotransduction. To investigate the contributions of CDH23 and PCDH15 to mechanotransduction and tip-link formation, we examined outer hair cells of mouse cochleas during development and after chemical disruption of tip links. We found that tip links and mechanotransduction with all the qualitative properties of mature transduction recovered within 24 h after disruption. To probe tip-link formation, we measured transduction currents after extracellular application of recombinant CDH23 and PCDH15 fragments, which included putative interaction domains (EC1). Both fragments inhibited development and regeneration of transduction but did not disrupt transduction in mature cells. PCDH15 fragments that carried a mutation in EC1 that causes deafness in humans did not inhibit transduction development or regeneration. Immunolocalization revealed wild-type fragments bound near the tips of hair cell stereocilia. Scanning electron micrographs revealed that hair bundles exposed to fragments had a reduced number of linkages aligned along the morphological axis of sensitivity of the bundle. Together, the data provide direct evidence implicating CDH23 and PCDH15 proteins in the formation of tip links during development and regeneration of mechanotransduction.
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Bortolozzi M, Brini M, Parkinson N, Crispino G, Scimemi P, De Siati RD, Di Leva F, Parker A, Ortolano S, Arslan E, Brown SD, Carafoli E, Mammano F. The novel PMCA2 pump mutation Tommy impairs cytosolic calcium clearance in hair cells and links to deafness in mice. J Biol Chem 2010; 285:37693-703. [PMID: 20826782 PMCID: PMC2988374 DOI: 10.1074/jbc.m110.170092] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The mechanotransduction process in hair cells in the inner ear is associated with the influx of calcium from the endolymph. Calcium is exported back to the endolymph via the splice variant w/a of the PMCA2 of the stereocilia membrane. To further investigate the role of the pump, we have identified and characterized a novel ENU-induced mouse mutation, Tommy, in the PMCA2 gene. The mutation causes a non-conservative E629K change in the second intracellular loop of the pump that harbors the active site. Tommy mice show profound hearing impairment from P18, with significant differences in hearing thresholds between wild type and heterozygotes. Expression of mutant PMCA2 in CHO cells shows calcium extrusion impairment; specifically, the long term, non-stimulated calcium extrusion activity of the pump is inhibited. Calcium extrusion was investigated directly in neonatal organotypic cultures of the utricle sensory epithelium in Tommy mice. Confocal imaging combined with flash photolysis of caged calcium showed impairment of calcium export in both Tommy heterozygotes and homozygotes. Immunofluorescence studies of the organ of Corti in homozygous Tommy mice showed a progressive base to apex degeneration of hair cells after P40. Our results on the Tommy mutation along with previously observed interactions between cadherin-23 and PMCA2 mutations in mouse and humans underline the importance of maintaining the appropriate calcium concentrations in the endolymph to control the rigidity of cadherin and ensure the function of interstereocilia links, including tip links, of the stereocilia bundle.
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Affiliation(s)
- Mario Bortolozzi
- Department of Physics G Galilei, University of Padua, Padua 35131, Italy
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Sliding adhesion confers coherent motion to hair cell stereocilia and parallel gating to transduction channels. J Neurosci 2010; 30:9051-63. [PMID: 20610739 DOI: 10.1523/jneurosci.4864-09.2010] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
When the tip of a hair bundle is deflected by a sensory stimulus, the stereocilia pivot as a unit, producing a shearing displacement between adjacent tips. It is not clear how stereocilia can stick together laterally but still shear. We used dissociated hair cells from the bullfrog saccule and high-speed video imaging to characterize this sliding adhesion. Movement of individual stereocilia was proportional to height, indicating that stereocilia pivot at their basal insertion points. All stereocilia moved by approximately the same angular deflection, and the same motion was observed at 1, 20, and 700 Hz stimulus frequency. Motions were consistent with a geometric model that assumes the stiffness of lateral links holding stereocilia together is >1000 times the pivot stiffness of stereocilia and that these links can slide in the plane of the membrane-in essence, that stereocilia shear without separation. The same motion was observed when bundles were moved perpendicular to the tip links, or when tip links, ankle links, and shaft connectors were cut, ruling out these links as the basis for sliding adhesion. Stereocilia rootlets are angled toward the center of the bundle, tending to push stereocilia tips together for small deflections. However, stereocilia remained cohesive for deflections of up to +/-35 degrees, ruling out rootlet prestressing as the basis for sliding adhesion. These observations suggest that horizontal top connectors mediate a sliding adhesion. They also indicate that all transduction channels of a hair cell are mechanically in parallel, an arrangement that may enhance amplification in the inner ear.
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